okay, if I have a 22lb scale plane with a O.S. 160 twin swinging a 18x6 "classic" prop putting out 7500 RPM and 11 lbs of thrust..pull if you will...will it fly? is there a general rule of thumb for thrust to weight? like minimums and maximums? [sm=confused.gif]

The short answer is that someone might have very general rule of thumb they could give you if they knew the plane (specifically the wing) type, but the long answer is no...not really.

All the thrust does for you is pull the wing through the air (which is what actually makes the plane fly). Different wings need different speeds in order to make enough lift to get the plane airborne. The wing ends up being the single most important factor in determining lift, so thrust alone is not nearly enough information. Any wing has a "coefficient of lift" which can get you to a number of how much the wing will lift at a certain speed, but that is not an easy thing to do. Other things such as drag, layout, etc also come in to play. Thrust to weight is not really a driving number in aircraft design, unless it is well over 1, and the plane can basically hover.

As an example, some competition planes I've designed are at the 55lbs cap at takeoff, and only have a .61 engine (roughly 10 lbs thrust). They fly, but not well. The wings are solely designed to handle that much weight without much power.

Pretty slow competition heh? I will expound on the aircraft type. I can see where that would make a tremendous difference. It's the top flight Stinson SR-9. I believe it will fly scale. A ton of wing area. As opposed to a pattern plane or the like with a semetrical wing foil.

Yeah we joke about the fact that our stall speed is 22mph, rotation is at 24, and overspeed is about 30mph. Very slow envelope.

I assume you have this fair lady:  http://www3.towerhobbies.com/cgi-bin...XNW28&P=FR

That being the case, I think you are pretty safe with that engine (and it is a beautiful one). The wing loading for the Stinson at 22 lbs is 34oz/sq ft which is high, but not tremendously high for scale flight (it probably won't snap roll ). It has a Clark Y airfoil at the root, which is a decently high lift profile, so you should be alright. Not meaning to insult your intelligence, but adding the flap option would help the groundroll too. Most of the easy flight calculations are for cruise, so getting to that speed may be a whole different problem. Either way, heavy planes eat runway.

These are all just estimations, but the reviews with that engine seem to be positive. Sounds like a pretty good match. That seems like a good RPM range too. We always say a stump-puller is better than a race horse if altitude is all you want

flaps , bells, whistles...all installed. engine runs beautifully. it has taken me since november 2008 to finish this one.

It should fly beautifly! Maybe as good as it looks static on the ground. Sounds very similar to a heavy L4 Cub I used to fly in terms of wing/power/weight. I loved it.

... and I have taken a whole lot longer than that to build some of my planes.

Have fun!

Bedford

There are a few things that will come into play.

First of 11 lbs of thrust on a 22 lb model will not produce an aggresive climb. But it will rotate and lift off.

At 7500 rpm and a 6 inch prop pitch the pitch speed is going to be 42 mph. Now this is only approximate since the engine may well unload in the air to a higher RPM and allow for a little more speed. But it's a decent enough number for consideration. So the prop is basically only going to accelerate the model UP TO 42'ish mph. That's all well and good if the stall speed is 25 mph. But if the stall speed is up around the mid to high 30's then there isn't a wide operating envelope. You may well find that the performance in the air would be better with a prop that has an 8 or 9 inch pitch and corresponding smaller diameter which still allows the engine to reach it's peak HP RMP. For example at the same 7500 rpm an 8 inch pitch prop would have a pitch speed of around 57 mph. That seems like a far nicer speed for your model to have as a max level speed. It will make takeoffs a little slower and longer and you'll need to watch the climb angle but once up to some altitude and at level the airspeed would be much nicer to work with. So some prop testing would seem to be in order.

You can also get an estimate on the stall speed by using Foilsim over at;
http://www.grc.nasa.gov/WWW/K-12/airplane/foil2.html

Input the numbers for the wing span and average chord and set the angle of attack to 7 degrees. Set the airfoil thickness and camber to closely simulate what your model's airfoil is like. Then lower the airspeed until you reach 22 lbs of lift. The airspeed that this occurs at will be a pretty good approximation of what your model will stall at. Hopefully it's down somewhere in the mid to high 20's. The less the better obviously.

Actually, when you get down to it, all the thrust has to do is oppose the aircraft drag. Drag is entirely dependant on aircraft speed, and the low end is entirely dependant on weight. So if you want an aircraft with a large speed range, or a good climb rate, then you must make it a light one. Obviously, an aircraft with built in headwinds (fully rigged biplane, for instance) will reach the T=D much quicker than something like a pylon racer. So the answer to your question is 'it depends'. Not a satisfactory answer, but 'it depends' on the design, the AUW, the task to be done etc, etc. Define the aircraft and the task, then you will get a better answer.
Evan, WB #12.

Hmmm...I wonder if we expect differing performance levels than we would with full-size aircraft. One light airplane, the Carbon Cub, advertises that it has 1 Hp per 7 Lbs of aircraft weight. It can take off in about 3-5 fuselage lengths, depending upon weight, and reach 7500 feet within 5 minutes. I guess the differences can be explained by the differences in model aerodynamic effects and full-size aerodynamic effects.

I wonder how much thrust a .40-size engine is giving that .40-size trainer that weight 4-5 pounds?

That seems like an interestingly easy calculation. I would agree that the prop pitch and RPM would be able to get you a maximum theoretical speed, but I'm not sure that is all you need. The pitch is a measure of distance traveled during 1 rotation in an incompressible fluid, with 100% efficiency. Since our props usually move at upwards of 0.2mach (at least in places) you definitely have to deal with compressibility effects (Prandtl-Glauert equations). When you start dealing with compressibility, the air viscosity becomes exponentially important.

In addition to that, you have propeller ineffeciency (which is huge in air), wake rollup, tip loss etc that all must be factored in to the props' "maximum speed". I know that number is just an estimation, and without doing the massive calculations you have no actual way of knowing, but that estimation could be substantially off if it was calculated for full scale or even a slightly different scale. One thing that seems weird is when Irun the rcpro calculator for any of my typical set-ups, they give me a number that is roughly my actualized cruise speed. Theoretically, the number from any calculator should be the propeller's max speed if it were by itself...adding the drag of the aircraft should put the max drastically lower than that, and in the OP's case well below the stall speed Iwould assume, unless the calculator is attempting to account for drag count. Seems fishy.

To use the cliche bee metaphor, any calculations done at even our scale wouldn't allow a bumble bee to fly. Viscosity (Re) is everything, especially between 0.2 and 0.9mach.

In general, we approximate flow as incompressible up to about 100 meters per second or about .3 Mach

22lbs weight..

11lbs of thrust..

as long as your lift to drag ratio is better than 2:1 it will fly... (a Cessna 150 has an L/D ratio of about 7:1)

Unless your scale aircraft looks like the apollo Command Module (L/D of 0.368) then you should be fine..

Seriouslythough.. that should be a nice combination of plane and motor..

<p style="margin-bottom: 0in; border-top-style: none; border-right-style: none; border-bottom-style: none; border-left-style: none; border-width: initial; border-color: initial; padding-top: 0in; padding-right: 0in; padding-bottom: 0in; padding-left: 0in; "><font face="Arial, Verdana, sans-serif" style="line-height: 0.17in; "><font><span style="background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; "><span style="font-size: small; ">Just browsing through the forum and saw this thread. Just wanted to give some input to the question. It's very true about what foutsjoe said about knowing the type of wing design in order to calculate if your plane can fly. Here is why:

In order for a plane to fly, the lift force has to be greater than the weight of the plane. In your case the lift force has to be more than 22lb.</span>

<span style="font-size: small; ">The formula for calculating lift force is L =1/2<font face="sans-serif"><font style="font-size: 8pt">&rho;</font></font>v^2A(<font face="serif"><font style="font-size: 9pt">CL)</font></font>
where L is the lift force,</span></span></font></font><font face="sans-serif" style="line-height: 0.17in; font-size: small; "><font style="font-size: 8pt; ">&rho;</font></font>is the air density, v is the air velocity, A is the wing area, CL is the lift coefficient at a certain angle of attack.<font face="Arial, Verdana, sans-serif" style="line-height: 0.17in; "><font><span style="background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; ">
</span></font></font><font face="Arial, Verdana, sans-serif"><font><span style="background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; ">
<span style="line-height: 0.17in; font-size: small; ">Air density is a function of air pressure and temperature. An air density table is easily accessible online for the correct density at your flying condition. But for estimation purposes, at sea level and 20 degree Celcius, the air density is about 1.22 kg/m^2.</span>

<span style="line-height: 0.17in; font-size: small; ">v is the plane's speed relative to the speed of the air moving across it. Ideally, assuming it's a no wind situation, v would simply be the traveling speed of the plane. </span>
<span style="line-height: 0.17in; font-size: small; ">you mentioned your plane produces 11 Lbs of thrust. The velocity of the plane can be calculated using F=MA where F is force (Thrust-drag), M = mass of the plane (in Kg), which is 22lb divided by 2.2, A is the acceleration of the plane (A=v/t),where t is the time traveled at that froce. so F = Mv/t,
Therefore, v = (thrust-drag)t/M. To calculate the drag, you have to know the drag coefficient of the plane, which is a function of the plane's geometry and surface material. It is a very complex calculation and it involves experiements for any specific shape. So let's just assume D is 0 for the purpose of this estimation. As such, we know that the speed would be somewhat less than what you would get using this formula, which we "boldly" assuming drag is zero(and we know in reality it's not). If you want to get technical about it, you could measure the speed using a speed sensor. Once you measure the speed you could use the same calculation to get the Drag and drag coefficient of your plane at that particular air condition. For your reference D =1/2<font face="sans-serif"><font style="font-size: 8pt">&rho;</font></font>v^2(Cd), which in this case A is the surface area of your whole plane.

Lastly, what you need to know is the CL. CL is a function of the lift coefficient and the angle of attack of the wings. And this is determined by the airfoil design. Each airfoil design has its own llife coefficient and it is represented by a curve. There are plenty of websites you can look up for lift coefficient for a certain airfoil design. Once you find the curce, you can get the value of CL at that particular angle of attack when your plane is running on the ground. You can now use that value to calculate the lift force your plane generates. If it's greater than 20Lbs, or 10Kg, your plane will fly. If not, considering getting a more powerful engine to get a higher traveling speed or find ways to reduce the weight of your plane. Hope this helps.
</span>
Here is a site you can look up data on different airfoils:
<a target="_blank" href="http://www.ae.illinois.edu/m-selig/ads/coord_database.html#K">http://www.ae.illinois.edu/m-selig/a...atabase.html#K
</a>reference: wikipedia
<a target="_blank" style="line-height: 16px; " href="http://en.wikipedia.org/wiki/Lift_coefficient">http://en.wikipedia.org/wiki/Lift_coefficient
</a><span class="Apple-style-span" style="line-height: 16px;">http://en.wikipedia.org/wiki/Drag_coefficient</span>
<br style="line-height: 0.17in; " /><br style="line-height: 0.17in; " /></span></font><font style="line-height: 0.17in; "><span style="background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; "><font face="serif"><font>
</font></font></span></font></font><font face="Arial, Verdana, sans-serif" style="line-height: 0.17in; "><font size="1" style="font-size: 7pt"><span style="background-image: initial; background-attachment: initial; background-origin: initial; background-clip: initial; background-position: initial initial; background-repeat: initial initial; "><font face="serif"><font size="2" style="font-size: 9pt">


</font></font></span></font></font></p><p style="margin-bottom: 0in"></p><br type="_moz" />

That's true but it makes one huge and incorrect assumption.. that is that the prop will make 11lb of thust constantly regardless of the plane's flying speed.
In reality, for fine pitch props such as used by the OP, thrust will decrease in roughly a linear fashion between it's maximum thrust at static and zero thrust at pitch speed. In this case pitch speed is a very low, lets say 50mph to allow for some unloading and revving out. Stall speed on the other hand assuming the previously mentioned 34oz/sq ft wing loading is high it about 30mph. Minimum safe flying speed then will be about 35mph. Assuming linear thrust decay then thrust at 35mph = 3.3lbok i accept that these are rough and ready calculations but they are enough to show that there is a big problem.

Sorry but with that engine and prop and at that weight i think this plane will struggle to get off the ground, and probably best if it doesnt because if it did struggle into the air it would be seriously underpowered and probably couldnt climb out of ground effect.

Maybe the OP will prove me wrong by reporting that it fies like a bird?

Steve
<br type="_moz" />

Steve
I have never understood the oft quoted comment that thrust becomes zero. We know that in a level flight, constant speed situation, L=W and T=D. If T is zero then so must be D - but I have yet to see an aircraft that achieves zero drag. At constant speed, level flight, thrust must be a positive number, not zero. In that situation T does not exceed D = if it did the a/c would accelerate until equilibrium was achieved.
Mike

It's just Presumption and Confusion operating together
formula : P+ C= BS
The thrust is really at "zero" only in that max speed has been reached.

Actually Steve has it pretty close to right. The top speed that the plane will achieve will be severley limited by the prop. And for a fine pitch prop of this sort the maximum thrust typically is found during a static situation or at some fairly low speed point.

Granted in level flight the thrust never does get to zero because to fly at a given speed the thrust will only reduce to where it matches the drag of the airplane. Which means that for a fairly heavy and draggy airplane the balance between thrust and drag is reached at a speed below that of the max possible pitch speed. But in this case it becomes even MORE dangerous for the model in question. If the safe takeoff and climb speed is around 35mph and the plane only reaches .8 to .85 of the maximum pitch speed then we're in some trouble. If we allow for an inflight max pitch speed of 50mph instead of the ground based RPM and pitch of 42 mph at .85 efficiency we've only got a top level flying speed of 42.5 mph again. So now we've got a takeoff and climb speed of 35'ish and a top level flying speed of 43'ish mph. That's only a speed range of 8mph. In effect simply going to half throttle with this setup means that it'll be gliding in for a landing AT HALF THROTTLE!

I don't doubt that the engine has more to offer. Which is why the suggestion was made to go for a higher pitch prop and reduce the diameter as required to maintain the RPM at up somewhere around the peak power or just below. A shift to an 8 or 9 inch pitch would allow for a much higher top level flight speed and less of a braking effect upon reduction of the throttle to a cruise setting.

This is a common misconception. That '85% efficiency means the airplane is only going 85% of the prop pitch speed'. It has nothing at all to do with it.

The widely quoted 80-85% prop efficiency is just a measure of how much of the engine's power is transferred to the prop, and is only useful for figuring out the change in top speed if a more or less powerful engine is used with another prop of about the same efficiency. Power relates more directly to the ability to climb as speed is related to the ratio of power to the 1/3 power.

A well matched prop generally moves the airstream of the prop blast about 10% faster than the airplane's actual speed. That roughly 10% higher speed is due to the thrust achieved which also equals the drag.

Yeah, maximizing capability of an engine by using higher effective prop or simply increasing thrust will solve the problem…

To answer the question, 50% T/W ratio will fly but depending on airfoil characteristic. You also need smooth and longer runway. For me as another option is to have an aircraft with lower drag coefficient. Select a more aerodynamic aircraft or try evaluating existing airframe and make necessary adjustment, or if it's cost effective to make a new one would be better. Having a low drag aircraft will have higher efficiency, higher attainable speed and higher wind capability. With the help of its own mass the aircraft can fly gracefully or even develop its own energy for critical maneuver that require higher rate of climb. The downside is your aircraft might respond to your throttle request longer but just give time because once it's stabilize you don't need that much power. To slow down is not a problem even if you don’t have much drag as speed brake.

To fly an aircraft with lesser power is in fact very challenging but gives you a lot of skills and knowledge about the reality of an airplane. Continue watching airspeed, your energy management technique becomes better too…

yes HighPlains,
There are SO many misconceptions in this thread, but let me elaborate on this one.
I too have seen prop efficiencies of 80-85% quoted, but that's for full size props, carefully designed for a specific purpose. And that will be their peak efficiency, at the particular airspeed for which they were optimised.
On models I'd advise using a prop efficiency of 50%, unless you go to great trouble calculating and experimenting to find the exact prop which will perfectly suit your model, and engine, and its intended purpose. The speed freaks do it, and get efficient props, but let's face it most of us fit the one in our box whose hole fits the shaft and whose numbers seem about right.

<div style="margin: 0in 0in 0pt">Now, who thinksa model can never reach its theoretical "pitch speed" (the product of prop pitch and RPM)?
I copied thefollowing table out of anold American magazine 20 or maybe 30 years ago.
The writer (sorry I forget who, but if you are reading please chip in) performed experiments with a 60 two-stroke in an aerobatic model using a wide range ofprops.
</div><table border="0" cellspacing="0" cellpadding="0" style="border-collapse: collapse"> <tbody> <tr style="page-break-inside: avoid"> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: windowtext 1.5pt solid; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: windowtext 1.5pt solid; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">1</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: windowtext 1.5pt solid; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">2</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: windowtext 1.5pt solid; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">3</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: windowtext 1.5pt solid; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">4</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: windowtext 1.5pt solid; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">5</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: windowtext 1.5pt solid; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">6</div> </td> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: windowtext 1.5pt solid; border-right: windowtext 1.5pt solid; padding-top: 0in"> <div style="text-align: center; margin: 0in 0in 0pt" align="center">7</div> </td> </tr> <tr style="page-break-inside: avoid"> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: windowtext 1.5pt solid; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">.Prop</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">static</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">static</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">RPM</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">mph</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">%max</div> </td> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1.5pt solid; padding-top: 0in"> <div style="text-align: center; margin: 0in 0in 0pt" align="center">% max theory</div> </td> </tr> <tr style="page-break-inside: avoid"> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: windowtext 1.5pt solid; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">dia x pitch</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">RPM</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">thrust</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">level</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">level</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">theory</div> </td> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1.5pt solid; padding-top: 0in"> <div style="text-align: center; margin: 0in 0in 0pt" align="center">(static rpm)</div> </td> </tr> <tr style="page-break-inside: avoid"> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: windowtext 1.5pt solid; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">APC 11x7</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">13100</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">7.5</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">13500</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">87.1</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">97.3</div> </td> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1.5pt solid; padding-top: 0in"> <div style="text-align: center; margin: 0in 0in 0pt" align="center">104</div> </td> </tr> <tr style="page-break-inside: avoid"> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: windowtext 1.5pt solid; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">APC 11x8</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">12500</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">7.75</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">12920</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">91.7</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">93.7</div> </td> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1.5pt solid; padding-top: 0in"> <div style="text-align: center; margin: 0in 0in 0pt" align="center">97</div> </td> </tr> <tr style="page-break-inside: avoid"> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: windowtext 1.5pt solid; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">APC 11x9</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">11500</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">6.25</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">11550</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">85.3</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">86.7</div> </td> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1.5pt solid; padding-top: 0in"> <div style="text-align: center; margin: 0in 0in 0pt" align="center">88</div> </td> </tr> <tr style="page-break-inside: avoid"> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: windowtext 1.5pt solid; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">APC 11x10</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">10500</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">5.13</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">11000</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">78.9</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">75.8</div> </td> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1.5pt solid; padding-top: 0in"> <div style="text-align: center; margin: 0in 0in 0pt" align="center">80</div> </td> </tr> <tr style="page-break-inside: avoid"> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: windowtext 1.5pt solid; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">APC 11x11</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">10000</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">5.25</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">10750</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">83.4</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">74.5</div> </td> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1.5pt solid; padding-top: 0in"> <div style="text-align: center; margin: 0in 0in 0pt" align="center">79</div> </td> </tr> <tr style="page-break-inside: avoid"> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: windowtext 1.5pt solid; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">APC 12x10</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">9250</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">5.75</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">9500</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">77.9</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">86.6</div> </td> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1.5pt solid; padding-top: 0in"> <div style="text-align: center; margin: 0in 0in 0pt" align="center">90</div> </td> </tr> <tr style="page-break-inside: avoid"> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: windowtext 1.5pt solid; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">Revup 11x7.5</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">12800</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">7.00</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">13500</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">86.2</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">89.9</div> </td> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1.5pt solid; padding-top: 0in"> <div style="text-align: center; margin: 0in 0in 0pt" align="center">96</div> </td> </tr> <tr style="page-break-inside: avoid"> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: windowtext 1.5pt solid; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">Revup 11x8</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">12000</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">6.63</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">12830</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">86.2</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">88.7</div> </td> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1.5pt solid; padding-top: 0in"> <div style="text-align: center; margin: 0in 0in 0pt" align="center">96</div> </td> </tr> <tr style="page-break-inside: avoid"> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: windowtext 1.5pt solid; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">Revup 12x6</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">12250</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">7.75</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">12750</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">75.2</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">103.9</div> </td> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1.5pt solid; padding-top: 0in"> <div style="text-align: center; margin: 0in 0in 0pt" align="center">107</div> </td> </tr> <tr style="page-break-inside: avoid"> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: windowtext 1.5pt solid; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">Revup 13x6</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">10500</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">7.88</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">12000</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">72.4</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">106.2</div> </td> <td valign="top" width="106" style="border-bottom: windowtext 1pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1.5pt solid; padding-top: 0in"> <div style="text-align: center; margin: 0in 0in 0pt" align="center">121</div> </td> </tr> <tr style="page-break-inside: avoid"> <td valign="top" width="106" style="border-bottom: windowtext 1.5pt solid; border-left: windowtext 1.5pt solid; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">Revup 14x6</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1.5pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">9500</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1.5pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">8.88</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1.5pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">11000</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1.5pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">69.7</div> </td> <td valign="top" width="67" style="border-bottom: windowtext 1.5pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 0.7in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1pt solid; padding-top: 0in"> <div style="margin: 0in 0in 0pt">111.5</div> </td> <td valign="top" width="106" style="border-bottom: windowtext 1.5pt solid; border-left: #ebe9ed; padding-bottom: 0in; background-color: transparent; padding-left: 5.4pt; width: 1.1in; padding-right: 5.4pt; border-top: #ebe9ed; border-right: windowtext 1.5pt solid; padding-top: 0in"> <div style="text-align: center; margin: 0in 0in 0pt" align="center">120</div> </td> </tr> </tbody></table><div style="margin: 0in 0in 0pt"></div>This table shows that using static RPM andprop pitch gives an accurate estimate of the potential top speed of the model, as long as the prop was chosen sensibly.
the table also shows clearly that this model will fly at 120% of its pitch speed (based on static rpm column 7), or 111% based on in flight RPM (column 6).
That is because the pitch marked on a prop is a pretty arbitrary number, whose main purpose is to compare it to other props in the range.
The pitch is generally measured using the flat bottom of the airfoil, NOT its zero lift line or chord line. That is in no way a criticism of manufacturers. I like simple, easily checked numbers.
This model can exceed its pitch speed on a 6" pitch prop because that is the WRONG prop for the model. Those fine props are suited to slow flying models, old biplanes or vintage types.
The very coarse props are wrong too, for performance. They yield only 80% of pitch speed, and were used just to satisfy the noise regulations.
Note also that the prop for highest static thrust produces the lowest flight speed!!! This is no way to choose a prop (see below).

Right, who said you cannot get zero thrust? Of course you can, if you fly fast enough.
check out the website www.drivecalc.de/PropCalc/
and download the program Propcalc. If you input a specific prop and RPM it will draw you a graph of thrust andefficiencyagainst airspeed. Note that thrust drops to zero as speed increases.
Note also that efficiency reaches a maximum at just about the airspeed that corresponds to "pitch speed"

<u>Choosing a Prop
</u>To choose a prop you want to know the stalling speed of the model, and my rule of thumb for this kind of model is 5 times the square root of the wing loading (in oz/sq.ft)
Say your loading is 30 oz/sq.ft, (the sq root is 5.5) times 5 = 27.5 miles per hour
You want a general purpose sport/scale/slow model to fly at double that, let's say 60 mph, which is 88 ft/s
Work out a prop pitch and RPM that produces the necessary pitch speed. At 7500 RPM you want 8.5 inches pitch, so an 8" or 9" pitch is called for.. Then choose the diameter that goes with this pitch AND suits the engines. What about a 17x8? or a 16x8, or a 16x9

Anyone know how much powerthose OS 160 FS engines produced? I can't find a test report.
My guess 1.5, at most 2 HP at 7500 rpm.
That is equivalent to a brushless electric model fed with 1500 to 2000 watts input, giving a power rating froma conservative 68 watts/lb to a generous 90 watts/lb. The electric fliers consider 50 watts/lb adequate for a big slow model, so I think the OS has plenty of power if given the correct prop.

forget static thrust, work out how much Power you need

The thing to remember about the prop pitch marked on our model airplane props is that there isn't a certification process anywhere that verifies the pitch is correct or true or anything.

The numbers on the prop are SWAGs by the manufacturer. There's a good probability that different mfg's have totally different ways the come up with the pitch number they choose to print on them babies.

Want proof? Next time you're in a LHS compare a couple with the same dia/pitch numbers printed on 'em from different mfgs. You'll see that for all of our discussion, including all the theories right down to the math, the discussion doesn't match the hardware we got to apply that theory to.

I've snatched up every prop pitch gauge I've heard about over the years. Every one shows the same thing. Our model prop pitch numbers aren't really reliable at all. And if any of them were produced by processes that were supposed to produce predictable results to match some formulas, then they've not done a very good job of it. It's not a surprise to discover one blade doesn't match the other on the same prop.

Theory is nice to know. But you gotta have a better matchup from what we have available for the theory to come close to applying.

Nice chart, must have been done around the 1985-1990 time frame. Because Fred's stuff came on the market about then and Chris's stuff came off shortly after his wife died. Having known both prop makers pretty well (and actually working for one part time during my college years) might give me slightly more insight on them. I never bothered to ask about how the APC's were pitched relative to how they were marked, since I flew mostly Rev-Up props for sport. We mostly talked about our racing airframes, airfoils that we were experimenting with, and silly things like pitch curve rather than the absolute pitch. Fred was heavily into racing, as was I, and since the rules didn't allow any change to the plastic props, the only variable that mattered was the radar gun. It kind of irked Fred in his early days to be the premier plastic prop maker, and have to fly wood Rev-up props in pylon. But when the availability of Rev-Up's got to be a problem, Fred was there with a good prop design that worked, and he quickly had dozens of designs to try on all the local guys.

Now Machin's Rev-Up's were from a completely different era, as he started making props back around 1949. His interest was free flight, with speed and performance events a close second. He was a contemporary of Goldberg, Axelrod, and many of the speed guys like Wienewski. Unlike Burgdorf, he did very little testing of his props, but sent out lots of samples to people that flew different events to see how they did with them. Part of the problem with doing a wood prop is the huge number of production steps where an error can creep into the process, and the relatively untrained personal that it takes to make them. Toss in the variables of a natural wood product, from stresses in the wood and differences in density due to different growing seasons and the orientation of the prop blank in a cross-section of a tree. Well you get the idea.

The wood props went through a long list of steps.
1) Cut the board to length
2) Rip the board to a thickness of three props and two more cut curfs. The thickness of each blank is related to the pitch and blade width.
3) Drill hole in each prop blank, sized for the smallest engine that might be used.
4) Shape one side of the prop outline
5) Shape the second side, keeping the prop blank within 0.002 of each other left to right, top to bottom. Shaping the outline was the only "skill job" and quite exciting to boot since a 3" diameter shaper head about 3" tall was fully exposed and running at about 25,000 was what you pushed the fixture with the prop blank into. Sometimes (about once every thousand or so) the prop blank would expose a grain defect and it would cleave off about half the blank at once sending it into a wood barrier that would stop it without allowing it to bounce by destructively absorbing the energy.
6) Rip the shaped blank into individual prop blanks
7) Cut the back side (flat side which determined the pitch), one blade at a time
8) Cut the curved side
9) Sand, flat side on a hard surface drum, curved side on a air bag drum, usually done by women. No balancing, just use the same number of strokes.
10) Sanding sealer wash
11) Quick couple strokes by hand with sandpaper
12) Stamp brand and size on opposite blades
13) Two coats of fuel proof finish
14) Bag 12 props along with label in poly bags
15) Ship to distributer and hope to get paid

Variation in pitch on a wood prop from one blade to the other was due to step 6 and how it related to cutting the airfoil. If the blanks were cut with a slight taper where the hub thickness varied from one side to the other, then when the flat side was cut, you would get the pitch variation, because the flat side of the prop was cut relative to the front side of the hub (the curved side). The solution is simple for a modeler that actually uses a pitch gauge, just use a razor blade and scrape the back side of the hub until it is the same thickness from side to side, which brings the rear face of the hub parallel with the front.

Having a slightly heavy blade is really not much of a problem as long as you know which one is the heavy one. Just align it with the counterweight on the engine, and you will never know it's not balanced.

As far as getting 80-85% efficiency, most modelers don't experiment enough, tend to over prop and often operating with a very limited knowledge base. The old Formula One guys spent an enormous amount of time making props with changes in pitch, diameter, and the pitch curve, which was how the pitch progress from the hub out to the tip. That along with area, blade thickness, and tip shape. Some even ran props that were unbalanced to help with the engine counterweight to smooth out the engine runs. On top of that a successful pylon racer had to stay on top of weather variations in density, humidity, and temperature to decide what internal setup would work for the conditions and which of the dozen of props would work with each particular engine available for the changing conditions. The one thing that drove up all up the wall was the dynamics of the wood. You could make two identical props and they would behave differently due to the grain structure. So often you made props that peaked at slightly different rpm on the same engine, and other time developed props that worked in heavy air, or still worked with slightly weak engines. The great props and great engines that came along the way were put away for the bigger contests.

Alisdair, are you sure? How can you get zero thrust "If you fly fast enough?" I always thought that, if you are flying, then there will always be drag, and the faster you go, the more drag there will be. One of the basic tenents I was taught was that in normal non-accelerated flight, then Thrust = Drag. Go faster = more drag = more thrust needed to do it. The only time T = 0 was when the thing was sitting stationary on the ground. Perhaps you meant that the apparent prop blade AOA was approaching 0 degrees/zero lift angle as the speed increased? Dunno, I'm confused...and you have always been a bit a guru at this stuff, published too...
Evan, WB #12.

You dive slightly, like with a glider. That has zero thrust.

When I flew the twin turbo-prop HS 748 we had to practise single engine flying. For that they throttled one engine back to a zero thrust condition to simulate a feathered engine (after we simulated the shut-down drill).
Zero thrust was not with idle throttle, it was just up (1/2" or so) from idle. Idle throttle would have given net drag at our flying speed. And that was with positive pitch on the props, flight idle pitch. Rolls Royce Darts did not have reverse pitch props. But they had two idle settings, flight idle and ground idle. Ground idle had virtually zero pitch, and that was for engine starting and deceleration on the landing roll. It gave a lot of drag on the landing roll. So flight idle had significant positive pitch.

HighPlains,
Thanks for the inside info on props. Interesting. More hand finishing than I expected.
I never used Rev-Up, but APC props are great. I use them a lot.
I wish they would have published Power absorbtion curves for their props. That would be useful.

DaRock,
The numbers on the prop are SWAGs by the manufacturer. There's a good probability that different mfg's have totally different ways the come up with the pitch number they choose to print on them babies.

What is a SWAG ???