APC Props?
 

Does anyone know why APC Props give out the most rpm output than other brands of props? What makes them better?

-Thanks....

RE: APC Props?
 

Who says they are "better"...? Better is a relative term... it depends on what you are looking for.

Sport APC props are optimised for low noise production. The prop blade shape they use typically makes for less blade area when compared to other "square" bladed props. That's the reason they turn up higher than other brands: less blade area, means less load on the engine... but also less thrust.

They also use "true pitch", opposed to "average pitch" used on most wood props and the likes. Average pitch makes for higher pitched prop tips, which also puts more load on the engine.

RE: APC Props?
 

well, i don't know about apc being able to spin at higher rpm. I have an ASP .46 on my venus and I put an 11x6 MA on and then an 11x6 APC. I was getting ~1500 more rpm with the MA. I know that may seem like a big difference, but I could clearly hear the engine rpm revving higher with the MA and the tach confirmed it. I'll definately be repeating this though. I do notice the APC weighing much more than the MA prop, which I would think would lend itself to spinning more slowly.

RE: APC Props?
 

I agree with your statement APC v MA, but, the APC is a more rigid prop and once up to speed will not flex like the MA will. From my understanding of it the flexing MA will give reduced thrust due to the fluctuating pitch.
As to the original question APC props at the price are prob the 'better' choice, but there are far superior props than APC you just got to PAY for them.

RE: APC Props?
 

I know they are not the best if you dont have the right plane for it or engine. I just got of reccomendations about APC props. I hear alot of stuff about APC this APC that so I thought I'd post here to see what you guys think. I just bought a couple of APC props 10x6 and 10x7 to try out on my plane,a modeltech me-109 25size with mag 52xls. I'm currently running a MA 11x6 on it that was sold to me as a 10.5x6 due to prop strikes, now its jsut 1-2/16 of an inch longer than a 10x6. I'm on the process of trying out props to achieve the fastest speed possible with a real good vertical performance. These APC props that I've bought are the first APC's that I've ever own, but like i said alot of people told me to use them. I've tried MA 11x7(wood), TF 10x8(wood), MA 10x6(11x6Nylon). Now I'm trying to see if these APC props might make my plane much faster. Any comments on that?

-Thanks...

RE: APC Props?
 

There are a number of very good commercial prop manufacturers out there. There are few folks who build some custom carbon and fiberglass props for certain applications too.

The reasons APC is recommended a great deal......

1) they are pretty consistant from prop to prop. Wood is inconsistant. Master airscrews are actaully pretty good too.

2) APC's tend to actually pitch out at what it says on the lable. And, as constructed, they keep their shape under load.

3) there are a variety of sizes and blade profiles which are optimized for different applications (speed, slow, electric, 3d, etc)

4) yes, most of the sport props are set up so they produce less noise. Less noise, tends to also indicate they are not creating turbulence, and are more efficient since they are not wasting that energy.

5) For speed use, the APC props are fabricated by design with materials which will permit/withstand higher RPM's than many other props. I wouldnt on my life turn a 10x6 master airscrew over 18K rpm. ( I do not recommend you run one on a SJ-50).

You will see an RPM difference between a MA 10x6, APC 10x6, a Tornado 10x6, a TopFlite 10x6, a Zingali or Zinger 10x6, a Graupner 10x6 and a Bolly 10x6. Different animals. The dia and pitch are not the only determining factors. Airfoil shape, blade profile, hub construction, tip design.... all play into things. Will the RPM's be close... probably within 1000 rpm or so...so yes. In the intial example, the MA might turn higher rpm on the ground, but in most cases the APC will unload better in the air, and pull much harder too.

Basically, when it comes down to it........for sport use... I typically fly what ever prop I have sitting around. I have a lot of old wood props to choose from, and assorted APCs from testing and stuff. I'm not real picky :) And besides, some of those old RevUp 14x4 props work great.

If I have a specific application where I wish to optimize something, be it speed, racing, aerobatics, funfly........ yes, then I go and optimize the prop for the job. APC props just tend to make that optimization process a little easier since they have a wider selections to choose from.

At Jett, Dub uses the APCs as baseline reference points. His APC 10x6 used for testing and engine setup is very likely the same as the APC 10x6 you might buy to operate the engine. So its easy to correlate performance.

Bob

RE: APC Props?
 

My testing has shown the APC props give out LESS rpm (and speed) than the others. [X(]
I started out with a 10-6 APC on an F-20....Rossi .45 long tuned pipe. I got a high
rpm reading of 14,000....which is pitiful !

I put a 9 1/2-6 Master Airscrew on it....the rpm jumped to 18,100. :D The speed
was about 20 mph faster....I couldn't believe the difference ! I too, thought there
must be something to this "new modern design" APC props.

I no longer have a plane with an APC prop. Did I mention they are fragile, and ugly as sin. :)

FBD. :D

RE: APC Props?
 

Dave,

We use to race Q-500 with the K&B .40 and MA 9x6 props. So I know what you mean. They are good props.

I believe what you were seeing in the application you decribed there was more the fact that you found a prop that allowed the engine to unload into the RPM range the engine and pipe were best set up for. The 10x6 would not let the pipe stage. If I can assume for a second that you did not re-adjust the pipe length while swapping props, and the pipe was apparently tuned for the 18K rpm range, there was no way the 10x6 was going to make it up to that sort of rpm... and it got stuck in the 'dead zone' of the pipe (which is worse than just having a muffler on there).

Prop selection is more a factor of what the engine wants for RPM, rather than what you want the engine to do with a given prop.

The MA 9.5x6 is a thin blade section (if I recall, slightly thinner than the MA 9x6, and checked at just over 5" pitch on the pitch gauge at station 5) . Its most unique feature.... was when running at higher rpm's it untwists slightly at the tips (de-pitch) which helps the engine unload even more. So what you saw was accurate. You get both decent ground rpm, which keeps the engine happy and staged on the pipe.... decent loaded engine performance for take-off, and then in the air the engine will unload a great deal further as the tips washout a bit more.

As you noted, that prop on the right setup can perform quite well. Definately no argument there :)

However, the equivalent APC prop would be more along the lines of the D1 series 9.5x7 which we used (at one time) for the sport-jett SS-40 engines. It was one of APC's first pylon props. BTW... if you can find them... they work very well on prop-jet type planes. Good balance between takeoff performance and top end speed, and are designed to function best in the vicinity of 110-120 mph.

The APC 10x6 is a 'heavy' prop. Thick blade, designed to turn more in the 14K rpm range. That is one of the reasons Jett uses it as the baseline prop for rpm comparison on the .40 size engines.

Bob

RE: APC Props?
 

Wow! Make this the 1,134th time while on RCU that I realize just how much I DON'T know about this hobby!

I am going to go back and hang-out in the Beginner forum, I MAY be able to help out in there---[X(]

Good stuff guys!

RE: APC Props?
 

Well said. APC D1 pylon props in general have a highly visible handicap – i.e. their enormous hub thickness being a concession to safety when using that kind of APC plastic material. Unfortunately that very thick inner prop part is followed by an unacceptable blade thickness affecting almost 75% of the entire prop diameter - impacting the top end rpms. Examples would be the APC 7.2*8.6 or the APC 8.75*9.5

Too much drag for serious speed application!

However, for the regular sport engine turning below 20K, APC performance is acceptable. Above that - as stated - there are the superior carbon fiber props available. A CF speed prop can be designed up to 40% thinner than a comparable sized APC prop, still featuring much better tensile strength and torsional stiffness.

Just check it out - switching to a suitable CF speed prop will easily gain serious rpms and corresponding mph. You will be surprised watching your engine turning into an animal! http://smiley.onegreatguy.net/devilfire.gif

RE: APC Props?
 

Forgot to mention: I am surprised that only very few speed freaks joining/posting this forum actually use CF speed props. A well designed CF speed prop includes a bunch of advantages!

I thought this is the Extreme Speed Prop Planes forum [>:]

RE: APC Props?
 

My plane is not really what you call an EXTREME prop plane but it goes around 120-130mph and is my second plane. Its a 25 me 109 with a magnum 52xls and tommorow I'm going to be trying an APC 10x7 on my first flight of the day and an APC 10x6 on the second. For the past couple of weeks or so I have been using a MA 11x6 which is now almost a 10x6 just like i said on my previous post. I think its a bit unbalanced and the tips are squared now. Speed was pretty awesome and people told me to try out APC props.

So, which one do you guys think is best for SPEED? APC 10x6 or 10x7? I tried a topflite 10x8 before just like someone recommended but it really just made my plane slower! I dont know if its because the prop was wood or because of the brand and the "powerpoint" tip that it has. Luckily I had a little prop strike and broke the prop right before the second flight of the day and changed back to my old MA 10 2/16x6 prop and the speed was much better. I will probably try out an APC 10x8 one day and see.

I just dont like trying to lean out my engine most of the time to get high rpm's so I thought these new props just might do the trick! Plus their new and more balanced, rather than my former prop which i think gives less rpm because of being unbalaced.

Hopefully the 10x7 works great tommorow!

-Thanks

RE: APC Props?
 

btw...what does pitch out mean?...is that good?

...and why are wood props inconsistant?

RE: APC Props?
 

Is that true? According to your current prop selection (6" of pitch) your engine has to turn about 22K reach 125 mph with that airframe...

Here's a suggestion:

1. Buy a tach to enable rpm number comparisons between different prop sizes and brands

2. buy a prop balancer (very important since almost all props come unbalanced in stock form). Carefully sand material from the front side of the heavy blade until the balance is achieved - preferably from the outer 50% of the prop radius to remove as little prop material as possible. If sanding the back side the pitch will be altered...

3. since the airframe is quite slim use APC 9*7 or 9*8 prop (should be tached at 15K static)

4. Macs products # 1150 non-muffled tuned pipe for absolute best performance (if there are no noise restrictions), or Macs products muffled # 1250 tuned pipe. Distance from glow plug along the centerline of header and pipe to the middle of the double cone part of # 1150 or the deflector plate of # 1250 = 12" = tuned pipe length

Good luck - expect terminal speeds of at least 120 mph :)

RE: APC Props?
 

So who makes these extremely good CF props ? :)

RE: APC Props?
 

Sonnich,

I highly recommend Bolly CF props:

http://www.bollyprops.com/bolcf6-8us.html

Super thin (especially the 6" and 7" dia racing props) + super strong

RE: APC Props?
 

Thnaks [8D]

RE: APC Props?
 

so here's a question I can't answer. How come if you use say a 9x8 apc prop and then switch to a 10x7, the plane won't go the same speed at full throttle? Anotherwords, the 9x8 might allow for a higer rpm, but wouldn't the 10x7, with its extra inch of prop be able to bite into the air more?

RE: APC Props?
 

Diameter = thrust
Pitch = speed

Well, more or less anyway...

You can have all the "bite" you want with your 10" prop, but if you don't make enough wind (to put it simple) you won't go fast.

A sleek, low drag airframe needs less prop diameter (thrust) to get up to speed... so you can use a small(er) prop on these planes, with more pitch for a high top end speed.
A big fat draggy plane on the other hand, needs more thrust to move... so you need a bigger prop. Since any given engine can handle only so much load, you can't just slap on a bigger prop with the same pitch, because your engine will no longer be able to turn that prop fast enough... so now you're losing power, because the engine is no longer running in its ideal power band. Therefor, when you go to a bigger diameter prop, you will have to choose one with less pitch. And less pitch = less wind = less speed.

Prop selection can be "interesting" sometimes... if you wanna hit that sweet spot...

RE: APC Props?
 

....[X(]....at 25 bucks and up....do you think they will sell many to us
"non racing" Sunday pilots....:eek:

RE: APC Props?
 

The price argument [:@]

I would describe it as follows:

CF speed props should be used by the speed addict who

- struggles for every mph (or wants to be faster than the fastest turbine jet at the field :D)

- flies super slim, low drag airframes

- already uses high performance engines introducing rpm regimes exceeding the mechanical/structural limits of APC pylon props

- enjoys the benefits of a well designed speed prop with superior aerodynamical performance (e.g. while experiencing transsonic prop tip speeds)

- wants a high quality hand made product

Figuratively, it is just like avoiding driving a Ferrari with standard wheels featuring a speed-limit of let's say 140 mph. And it is the strive for the best possible transformation of rpm into speed.

To come back to the price issue. Yes, at first glance the price seems to be too high. Assuming you already have your favorite 'absolute best' speed prop, in other words your 'master prop' being a result from lots of trial and error test flights with accompanying speed measurements, you can start with the prop moulds. The procedure to establish a good prop mould is very very time consuming.

To fabricate one single CF prop takes also some time. That is preparing the correct lengths and numbers of the CF rovings and their layout. Also weigh out the epoxy resin. Accurately wet and place each roving without producing any air bubbles. Then you carefully have to operate a squeezing machine (press) to remove excessive resin resulting in a mess. After the first 10 hours of curing at room temperature each prop has to be tempered in a kiln for several hours at 70° Celsius to acquire the outstanding material properties. Take the CF prop blank out of the mould and finish it meaning shaping the edges and fine balancing. All things considered (material, time, electric current) that price is justified from my point of view...

RE: APC Props?
 

Heh...CF props are just too expensive for me now and I'm not that MUCH of a speed nut but I do love speed enough to really want to go fast! I'm somewhere around the middle. Too much speed for me are the Q500's and are just too uncomfortable. Looks also matter for my plane.

I love speed but, I wouldnt wanna buy a tuned pipe and sacrifice scale...the big muffler on this 52XLS is already big enough. Some people "exaggerated" and said that my plane went about 190-200mph which I think is not true and would have torn up the airframe. My plane have smoked some turbine jets at the field the other week but I dont think it can smoke the other really faster jets. I'm not trying to go toooo fast because this plane is already fast enough for me as this is my second plane. Its just knowing that I'm not reaching the full potential of this plane makes me cringe.

So here are some pictures of my plane, engine and the APC 10x7 Prop:

RE: APC Props?
 

HI DER STEUERMANN! Without your input and the time that you spend here, this wouldn't be half the EXTREME SPEED FORUM that it is already. You deserve a big THANKYOU in general! To be honest, when I was first introduced to this forum I was a little bit dissapointed by the average level of performance here. I was expecting this to be more of a top fuel dragster version of the pylon forum. I appreciate all the planes that I see here, don't get me wrong. I just thought that there might be more of a well established core group of guys here in the 200 club with engine mod tips, air frame work to share, and prop science to discuss. Any way, thanks again professor!

GPITTS, real nice looking plane! If you go to APC props on line catalog you will find a nice assortment of $3-4 props that you don't normally see at the hobby store. If you find one that you really like after doing $20 worth of research then that would be money well spent.

RE: APC Props?
 

Hey, I just got back from flying and the APC 10x7 prop sure made my plane much faster...probably 10mph faster. What also happened was surface flutter![:o] Real scary sound to hear. It was my first flutter ever. The extra boost of speed sure made the control surfaces shake alot and made my rudder vibrate loose! The only thing that was holding it onto the plane were the tail wheel and the control linkages. Aileron servo tray was also loose. Tommorrow I will try to see if my control surfaces are ok and that they dont flutter anymore. All the clevises, servos, control horns were all fine. I will test my luck tommorow and see. Today was just a real crazy day at the field and its a miracle my plane is still in one piece. 2 mid-air's happened today and it was real horrible. The other guy that mid just lost his other brand new plane yesterday....I feel sorry for the guy. There was also an incident where one guy was running his plane in the pitts and the prop flew off and almost cut some guy's head off!. I came in late in the day and I dont know what else happened earlier. Bottom line APC props do pull harder in the air even though they have less rpm in the ground. I'm pretty satisfied with this prop but it did stress out my airframe a bit.

RE: APC Props?
 

HHHMMMMMM..., der_steuermann, first I must tell you that I am grateful for the web address link to the Bolly carbon speed props. I had looked at their product range fairly closely 2 years ago when I gambled to stock their 26 thru 32 inch diameter props for customers at my workplace. The big props were dismally inferior to the Mejzlik props simply because the solid carbon tow construction made them grossly overweight for the fast rpm spool-up needed in 3D flying or even T.O.C. level I.M.A.C. work.
But when I researched them back then; although I found alot of the small special application high RPM props very interesting, none of the exact pitch/diameter combinations matched my needs for my speed models. Now that I have glanced at Bolly's site again; thanks to you, I noticed that they offer the option to custom re-pitch their carbon props for you to your specification!
This suddenly opens their potential up for me. ThankYou!....


Best Regards, Chuck Roundy