Giant scale props

[megawatt]

I am just finishing a 104"" Super cub, and am searching for a prop.Something in the 18-20" range.(E-Flite power 160,30 Elite 3600 cells,CC HV85 esc.)I wood like to use a wood prop for the scale look, but am wondering about the performance tradeoff in an electric specific prop vs. a general duty(read: glow/gas) wood prop. This is not a "hang on the prop" 3D application, but efficiency is a factor as I am hoping to maximize run time untill budget allows Lipo's.
Giant size scale builders care to comment?
Thanks
Jeff

[F1 Rocket]

I had a DPM 88" Clipped Wing Cub that I used an APC 20x11e cut down to 19". I painted the back side of the prop black and painted the tip white. Looked very scale like (Super Cubs generally have metal props) and pulled the plane well.


Danny

[feathermerchant]

Call Ben at 3Dhobbyshop.com He has the Xoar wood props. They're supposed to be pretty good.

[GordonTarling]

I use wood props on my larger models - they look much better and can easily be dressed to look even more scale, if that's what you want. Brands I've used include Zinger, Master Airscrew and Menz - not noticed a huge amount of difference between them.

[megawatt]

Thanks guy's, for the replies.The larger e-specific props seem hard to find.Looks like the APC thin series is just about all that is available.I do like the looks of the woodies!

Jeff

[FlyingW]

If you need more pitch than 10 or 12" you need to make it yourself. With the help of Ken Myers and his sharing of some of Kieth Shaw's prop making tips, I was able to carve and sand down a Zinger 24x16 wood to make a reasonable electric prop for 3,400rpms.

The tips included: (1) sand the tips to a better airfoil shape. (2) round the tips. (3) sand off the corners near the hub. (4) Thin the trailing edge as much as possible. (5) do what ever you do exactly the same on both blades.

It seems to work well. I wish APC made 24x16s though.

[GWRIGHT]

Yes, Zinger has always made very good prop blanks <G>

[wrenwright]

Has anyone (Gary?) ever quizzed APC why they offer such a poor selection of larger props? Specifically ones that have over a .5/1 pitch to diameter ratio? If they were to make a 24x16 in addition to the 24x12, I would surely buy one, probably two or three. I wonder how many props it takes to make it worth it for them to make a new size?

[GordonTarling]

APC have always been very responsive to requests for new sizes - if they see a need, then they'll make it. So, YOU need to let them know!

[Jocke]

Im working/helping with Tomas Mejzlik with the electric carbon props, Mejzliks wants to make more size options to there E, WE and TH electric serie, but the big problem comes to chose what props sizes to go ahead and get out in production, i have asked before, but if anyone has any input or advice on what props sizes that should be avalible, then let me know, from 18" to 30+", TH serie can also be 2 or 3 blade.

[solomonx]

Hi Jocke,

About how much more draw, percentage wise (loosely), do the WE props draw over the thin electric version? I know with electrics you want to go up in diameter and pitch to match thrust and speed of the gassers, but if increasing diameter is not an option, would it be advisable to go with the WE prop to gain thrust?

Thanks,

Ken

[Jocke]

If my memmory are with me, the 20x11" w gave 400-500g more trust on same setup, i will have to get another HD for exact messurent data, the wideblade props are avalible fo pepoe tat wants more trust on same setup but not willing to go up in diameter.

[wrenwright]

I'll toss out a few suggestions as it's very hard to find larger props that have over a .5:1 pitch to diameter ratio.

Here are few that I would like to see:

18x16
24x16
28x 22

I would like to see more props around .75:1. The lower ratio props are ok for 3D applications, but for sport flying I think there are better ratios.

I know the Mejzliks props are very high quality although expensive. I wish APC would come out with some in the above sizes as their props are reasonably priced and work well for sport applications.

[Jocke]

For what motors would those props work, they seem to have very high pitch?

20,5X12"WE

20x11"E

20x11"WE

20x12"E

22x12"E

22x12WE

26x15"E

27x12" TH-3blade

24x10"TH

26x10"TH

27x10"TH

27x12"TH



These are the electric props avalible today.

[rcelectfly]

For what motors would those props work, they seem to have very high pitch?

Jocke,

High pitched props like the ones he is asking for work very well on geared inrunners. For example a NeuMotors BAM motor flies great with a 28x22 prop. I wish that Mejzlik would make that prop. People are using custom made wooden ones on their BAM's but they would prefer to have a good carbon fiber prop instead.

Chuck

[FlyingW]

I second the 24x16 size. Good call Wren.

[R/C Dallas]

IMHO the 24x16 would also work great for a lightweight setup in a 27-30% size IMAC bird using a Hacker A60-18L or Hyperion Z5045-18 on 10S. As it is, I hope to try an APC 26x15e on 10S on my 31% Extra.

[Jocke]

Jocke,

High pitched props like the ones he is asking for work very well on geared inrunners. For example a NeuMotors BAM motor flies great with a 28x22 prop. I wish that Mejzlik would make that prop. People are using custom made wooden ones on their BAM's but they would prefer to have a good carbon fiber prop instead.

Chuck

Looking at todays motors its only the BAM that swings that kind of props, other manufactors aiming for more rpm and less pich, making an carbon electric prop to only work good on "one" motortype will be hard, and the market not big enough im afraid.

[Jocke]

The 24x16 you recomend works good on the Hyperion, also on a few other motors and setups, im also thinking about the 24x12" with the E design to close the gap between 22x12E and 26x15E, also a lower pich version of the 26"E.

Looking on bigger motors/setups for the TH version maby 27" to 32" with pich of 12-14", would work good on many diffrent motors with 12-15s setups.

[rcelectfly]

Looking at todays motors its only the BAM that swings that kind of props, other manufactors aiming for more rpm and less pich, making an carbon electric prop to only work good on "one" motortype will be hard, and the market not big enough im afraid.

But if there were props available then more motor manufacturers could make motors fot the prop. Which came first the chicken or the egg?

Chuck

[Jocke]

Motors same first, after that there was a growing demand for elctro prop for big scale that are efficient and can handle the power, the information ive got there will be no simular motor as the BAMs from any other manufactorer in 07, 08 releses, maby in future the trend will be diffrent, but as i see it now and near future there is only a smal market for that kind of props, its a huge effort and time consuming task to devolop and produce these props, but i will pass the idea to Mr Mejzlik..in the end its he ho desides what will come into production.

[wrenwright]

For what motors would those props work, they seem to have very high pitch?


They would work on any number of motors.

I don't think those props I listed are high pitch at all. A high pitch prop to me is one that is over .8 in ratio of pitch to diameter. .5:1 such as the 24x12 is pretty slow to my way of thinking.

Consider a 24x12 prop turning 4500 rpm only has a pitch speed of 51 mph, so the it has to maintain a considerably high rpm just to keep the plane in the air. I think AstroBob said it best when he said that props with a lower than .5:1 ratio are best suited to stirring paint, not flying planes. Granted, if all one wants is to hover and fly 3D, that's another thing altogether as those planes are kept in the air by thrust, not by the wings traveling through the air and providing lift.

[wollins]

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[bhchan]

For my BAM 2215-2Y I am using a 26x20 and 28x20 wood prop. Got them at Tennensee Prop. I also talked with the people at Xoar, they will custom cut prop with a minimum set up cost.

Brian, an EAJ