Japanman

Along with a bit of other stuff, I got some apc 6/4 electric props to try.
They look great for 020 texaco as well as 049 stuff- but any more power than that and I`d say the`ll start to flex.- They are very much thinner at the root than the 'gas' apc props
(now I know I`m full of hot air, but GAS powered?)

Cut down to a 5/4 or 4/4 they may have some potential- but I`d say they may get a bit stressed and a fair dose of caution with a safety glasses sundae may be in order. I wonder how many other good electric props there are out there?

BTW_was this the prop you tried (cut down)on your speed plane Matchless?

J.M

BMatthews

STOP RIGHT THERE ! ! ! !

DO NOT EVEN THINK ABOUT USING THESE ON AN 049 ! ! ! The hubs are too weak to withstand the high rpms of an 049. Especially the revs that would come with the 5 inch cut down sizes. Add to that the power loading and shock from the ignition versus the smoother torque of a motor and you have a recipe for a nasty accident. There is just not enough material in the hubs of the electric series to withstand the forces that even a Black Widow or probably a Baby Bee can generate.

As for the PeeWee 020 Texaco stuff I'd offer a cautious OK but only for the 6x4 or larger to hold back the revs. And I would do the first test runs with safety equipment on and constantly check the hub and blade roots for signs of the whitish stress marks that APC's generate when pushed too far. Even with a PeeWee I seriously advise against using a 5 inch electric type on it. Here again the revs and vibration loading could easily overcome the skinny hubs on these props.

combatpigg

My Feedback: (3)

I'm using the 4.2-4 E prop on my piped CS and it is working so far. I just treat it like I am using a die grinder with a cheap cutoff wheel.

Japanman

BMathews,
Sometimes flexibility is not a bad thing. think of a cox rubber ducky.
My feeling looking at these props is that their extra width and pitch near the root would slow down a cox 049 enough to be safe- they MAY flex around a bit through the firing pulses but I don`t think that it will be enough to make them break- unlike most other props they are flexible progressibly from the hub outwards- with no real stress raisers.

Certainly I mean to keep an eye out () for signs that the prop is exceeding it`s elastic limit , and the first few runs`l be with safety glasses.

J.M

combatpigg

My Feedback: (3)

The question is MARGIN OF SAFETY. The props are tested to the point of failure, and the safe limits are set at what ever the manufactures' conscience [and tolerance for legal exposure]allows. The 4.2-4 would make a good subject to be duplicated in carbon!

BMatthews

While I certainly do not condone using these props there's no arguing with these results. If it's good enough for a CS on the pipe I suppose it's good enough for a reedie.

Just be super careful and watch for hard "landings" that may stress the hub too far. I suspect that a lot of APC's warnings are based on flex damage and the ability to still hang on with some measure of that. With the small E hubs there isn't much safety margin.

I really like CP's idea of using the E props as a plug for a carbon version. Or carbon with some kevlar for flexibility.

ZAGNUT

My Feedback: (1)

and it would be easy to add a little meat to the hub area before making the mold...


dave

Japanman

I was thinking the same thing about using them as plugs for moulding carbon props. Many stock props for glow seem rediculasly thick near the hub- I often imagine how a 4by 3 made by cutting down an apc 7by 3 - I bet it would not be very effecient!
It makes me wonder how much power is being wasted churning up the air in the inner prop disc for many props.

IMHO I suspect that this thickness is more to do with crash resistance than anything. I imagine that because people start glow egines while infront of the prop, it makes for a liability problem.


J.M

jessiej

[I was thinking the same thing about using them as plugs for moulding carbon props. Many stock props for glow seem rediculasly thick near the hub-]

Especially in 1/2 a sizes. Compare an older wooden Top Filte 6x3 for example, with one of current production.

The newer props are positively club-like in comparrison. I cherrish my supply of old Rev-ups, power props and the like.

jess

combatpigg

My Feedback: (3)

At the N.A.S.S website there is a link to a guy named STEVE WILK who either makes or deals ELIMINATOR props that are semi unfinished CF. He has almost an infinite selection of 1/2A speed props [is 20 different sizes almost infinite?] I kept increasing the aspect ratio of his 4.2-4.2 until the GZ got happy!

BRUCE, SAM KINNISON had a line," I don't condone wife abuse, but I understand it".