So right now I am at less than half of that figure for wing loading...That should mean that it should require a lot less power to match their speeds.
As far as induced drag, it did seem that there was no real noticeable increase in speed with this plane in a steep dive. The best performance seemed to be when just a long wide turn, or shallow dive, before straightening out seemed to give the best results.
It seems to me the best approach would be to keep the AOA as low as possible and HP as high as you can...

Could you check these #'s and see if I have it right?
297.87 ft/sec forward speed
29584 RPM with a 5 inch prop
29584/60 = 493
(5xpi)/12 = 1.308ft
493x1.308 = 644.84 ft/sec tip speed static
644.84 x 644.84 = 415,818.62
297.87x297.87 = 88726.53
sum = 504545.15
square root of 532,186.49 = 710.31ft/sec tip speed or 484.3 mph??? (what Mach.# is that?)
At least I'm back at the first figure I got for prop tip speed I still can't believe it was possible.

The only problem with these numbers is that the plane would have had to outrun the prop/pitch speed by 50-60 mph...

Edit to correct transposed numbers!!! the forward speed figure was supposed to be 297.87 ft/sec not 443.08 ft sec (203.1 mph not 302.1mph) sorry about that.

My stall or theirs?

That is a shade over 300 mph, so the numbers might be a bit suspect.

Pitch and RPM would give a 140 mph speed.

Actual model speed would be around 10% less, depending on how draggy.

Well the number was supposed to be 203.1 mph or 297.87ft/sec so much for trying to do two things at once....I screwed it up right from the start....
On Waveoscope enhancing the audio on the last speed pass I got a figure of 203.1 mph (326.86Kph) but that is still suspect, still it covered 450' in about 1.5 sec. That is still no accurate measurement methood so I can't make a claim to that speed... I was just trying to make some sense out of it and the prop tip speed would have had to be very high to get there.
Given that the prop pitch speed figures at that rpm I got was in the 140-150 mph range I could not belevie it was possible to out run the prop pitch speed by that much, although I do recall reading that small props often do outrun the prop pitch speed.
This plane should be fairly clean as far as drag goes, as well as flying at a very low AOA...

It isn't hard to clock a plane. I like to use 2 cars, 2 cell phones or walkie talkies, 1 stop watch, 2 folding chairs and 2 helpers.
Measure off a distance...528 feet is a handy one.....and station both cars at the extreme ends. The cars provide protection and a point of reference in the fore ground that the observer can use to line up with his point of reference in the background.
The 2 observers can work out the procedure that works best for them, but we have the guy at the finish line hold the stop watch and the guy at the starting point tells the other guy when to start the clock.
After doing it this way for a number of years and dozens of clockings per outing, it's amazing how CONSISTENT the clockings are. Usually within a 1/100th of a second of each other on runs that sounded the same.
Once you have established a point of reference doing it this way, then your Wavoscope or radar gun readings become supplementary.

BTW guys, don't get too focused on the prop pitch. The idea that the plane really shouldn't go faster than the prop pitch would predict overlooks the fact that our model industry prints whatever pitch they feel like on the props they create.

If you've ever had your hands on a prop pitch gauge you wonder how the model prop industry stays in business. You'd be amazed how many two blade props have two different blades. But that's not the point either. Not only are the tolerances pretty sloppy, but checking from one prop to the next shows differences, and from one line of props to another shows large differences, and from one brand to another. Seems everyone is lying right? Not at all. Everyone has labeled their prop subjectively. Their choices often aren't anything more than a WAG.

Don't get your knickers in a twist about your model's speed (no matter how accurately timed) being faster or slower than "it should have been" based on the number printed on that prop. It's nothing but advertising. Never has been anything more for us modelers.

Kewl.....

Back when pylon was growing in popularity, a bunch of guys did many versions of what you describe. My bunch did almost exactly what you mentioned only with two watches. Both timers had one. When the start guy punched his he said "start and both guys punched their watches. When the finish guy said "stop" both punched their watches. Averaging the two times made us believe we were more accurate. They often were within 1/100th.

Well, actually we didn't do it exactly. We never thought to use cars.

As for radar guns.... lol......... we didn't have them yet. And couldn't figure out how to use a Whammy without risking cutting the hoses. Or getting one from a highway cop.

Chuck,
That sounds like a far better method than I used. Standing by the side of the runway about midway estimating when it crossed the ends counting thousand one, thous...hit, man that's awfully quick. Perhaps I can get a couple of guys to try two stopwatches with cell phones...
Anyhow like I said, the primary goal was to see if a plane with a 3/8 thick wing could make it past 130 without blowing up from flutter, and that I pretty sure that it did. Now it's just a case of, how fast can it go. This is the fastest plane I've ever built and I'm still not sure of what I am doing.
It was pretty darn quick on that last diving pass...

Da,
The 5X5.5 apc pitch seems to vary and isn't even close to a constant progression, kinda weird but it looks pretty mean.
So basically what your saying is that prop pitch is more of a guess than actual measurements made?

Hopefully in the near future I can get a good audio to get Doppler off of, without having play with it just to get some type of reading that's at least shows something. The guy doing the last video has a radar gun but couldn't find it that day, but he got a good video of the flight. After the first flight I was just as happy to get a video of the flight just in case something else came off or went wrong, thinking that it would give me some clue as to what failed.

Prop theory and practice deserves an entire thread, perhaps a greater mystery to making a great prop than the rest of the airframe. I worked for one prop manufacturer that made the best wood props, and knew another pretty well that makes great plastic props.

From gauging many hundreds of props over the years, what I figure is if the mfg's have some kind of theory they base their pitch/progression/blade area/aspect ratio/tip shape/airfoil/thickness/flex/stiffness/and a few others on, many of them blow it by poor quality control. Having done some QC on the props I've bought, I really didn't see anything that led me to believe they had any way to design and produce props with anything close to a guaranteed pitch.

If you think about it, the power input to the prop would have an effect on the performance. They're telling you with their advertised pitch what performance you're going to get and they only have a rough idea what power you're going to have to apply, how big/heavy/slick your model is going to be and a few more.

Good thing is whether or not a prop "over produces" means almost nothing other than that prop mfg didn't brand that line of props with powerful, small frontal area, slick, light models in mind.

The" best prop" can not be calculated - it can be not even be predicted - just guessed at
Why?
the prop is part of interaction with model and power
IF you had electric power and telemetry ,you could read power consumed at full load possible , then start changing props to find th one which went the fastest at full motor power
On glow/ gas engines, the guess work gets harder as rpm does NOT equate to power being fed into the prop-
If you are diving to gain speed - then all bets are off

APC is one company [out of a few] that is really on the ball when it comes to making props for specific applications.

I assume this 5 x 5.5 that IE is using is a competition series E prop..? There must be a whole class of speed plane out there that uses them. The class can be at "cult level" such as 1/2A CL Combat for example and they will still make a prop to fill that niche.

I don't think they make any props that do not have a well thought out and proven purpose ahead of time. They won't carry a size for very long that loses relevancy due to a rule change.

I can't say enough good things about APC because I fly a lot of "off beat" fairly specialized stuff and they have an outstanding prop choice for evey application.

Well this is an APC 5X5.5 speed prop(?), it is the prop I tried after the 6X5.5 used on the maiden. I went with a smaller prop on the second flight based on the idea that the 6 inch was too much disc load for the 3.17mm motor shaft, where the motor shaft bent during the first flight. For me prop selection has never been a critical factor with sport flying being my primary focus. Typically I looked at the thrust produced and worried little about top speed. At least with this plane I do have telemetry from the Castle Creations Ice ESC, so I have some idea of what my power and RPM figures are. It is that data which led me to a point in the flight where (during a diving pass) I saw the rpm peak at 29586 rpm with a real big dip in current (under 400 watts) ( this is where I thought I got my best speed).
The only thing I am sure of at this point is that I am not loading the motor anywhere near it's operational limit as far as power or rpm, and should be able to get a bit more performance out of the airframe. The next flight I have the motor timing set hard or advanced so I am going to be able to push more power through the motor, hoping to see a bit higher operational rpm.
With this airplane I am way out of my comfort zone as far as "knowing" what to do and am going to have to rely on the advice of those who have "been there" to tune it for optimum performance.

I don't know very much about electric setups, but if RPMs go up and current draw go down [and you aren't in a dive]...I would suspect that the shaft is spinning faster than the prop.

Every APC prop I've tried in a speed application has delivered real world MPH numbers that matched the theoretic [projected] speed pretty closely.

The biggest anamolies I've heard of with their props is how the 9 x 7 sport prop out runs the numbers on Q500 planes....

and the 10 x 7 sport prop on a Patriot was shown [in a RCU thread] to behave more like a prop with more pitch.

Very interesting...
Thankfully the plane was in a dive when I got the spike in RPM and dip in current/power. (Funny the first thing I did was check the prop adapter to see if it was slipping and it wasn't).
Hopefully this afternoon I can get a flight in and be able to get a bit more data. I am going to set up the camera on a tripod near the runway and see if I can get some data for doppler readings. Right now while I have data from the ESC I have no idea of what the flight speeds are.
I'm still pretty sure that for any real speed I am going to have to try this setup with either a 4 or 5 cell battery, the motor is supposed to be able to take a 5 cell in burst operation. The one down side of the higher cell count is having to go with a new charger as well. My current charger for Li-pol batteries is around 7 years old and can't handle the new high current high cell packs.
Still when it comes to prop selection I am guessing at what I am doing, right now I'd like to try a prop that is about the same diameter with more pitch, something like a 5X7 or 5X8 would be nice.

Edit to add:
Has anybody seen this plane?
http://www.boeing.com/Features/2011/..._05_04_11.html
They stole my fuselage idea! lol

IF rpms increase with same power input - the load on the motor has decreased
same on a glo setup-or gas
A glow setup which unloads in a dive is NOT making more power -it is simply under less load
Some guys lean out glow setups sothat tey screm inshllow dives but are lean in level flight and they sag in sustained climb
this is typical for an IC engine
ideally you want max horsepower in level flight and finding prop which does that is cut n try.
Torque can beincreased using a tuned setup -which increases max hp - rpm
again cut n try
On control line the pipe setups were set so short that the plane had to be 'whipped to get it up to tuned resonace rpm- then the models would take off like a goosed goat - the mix was always rich to allow th settingto be correct when it hit piped rpm
You cant get more power with less fuel - can you?

RC Speed engines are tuned and propped so that the dive is needed to get the engine into an rpm range where it can hit it's highest stage of resonance. At this point the engine gets the explosive jump in RPM and continues at this power level the rest of the flight.
These engines do have the fuel / air handling capability to get to the highest power threshold with the help of the dive. At this point the fuel comsumption is off the charts.

With an electric you have you maximum power available from the start, so your main concern is not to overload the motor for extended times as I understand it. With a electric motor your power is constant and dependent upon the load the prop presents to it, or the draw if you will. If you look at the flight data you will notice an interesting quirk to an electric motor it get it's best efficiency at the top end, as the prop unloads the load to the motor or power required actually drops off a bit. During the flight the average power draw was around 425 watts roughly half the manufactures rated nominal power (whatever that means) I am taking it as the max continuous rating. When the prop unloaded the power level dropped as low as 125 watts my guess is at that point of time the motor was at close to it max efficiency, I bet the prop was keeping the plane from going faster then.
Edit to add:
Never got to fly today, got involved in putting a new roof on a building at our clubs' field instead.

Your electric motor may have reaced max rpm with the esc setup
there is a limit to rpm on brushless
You may need to add more prop load-to put max power in the speed range you are shooting for

Dick I have got to play around with the setup something ain't right. As far as the rpm more cells is about the only option I know of with a brushless, while the ESC timing might help a bit it not going to give any big results.