Re: Good starting Penny plane prop pitch?

From: <jwfinn_at_lycos.com>
Date: Fri, 16 Dec 2011 14:49:40 -0000

Mike, I form mine on a 4-5" cylinder using p/d 1.8-2.0. They seem to work best in that range. Lower and you risk blade tuck with a flaring prop, higher and you run into pitch reversal with flaring blades. All of the blade area is kept forward of the spar to maximize flare, and I use carbon spars to maintain impact resistance while still having it floppy enough to flare under the torque of a thick motor. Make sure your wing spars and motorstick are good and strong though, as those take a lot of punishment and need to be rigid so the model won't twist up and dive when it hits something.

Flying F1D in low ceilings requires either heavy flaring, a good VP, or VD. I've never used a flaring prop on F1D and would think it to be pretty difficult, albeit easier to build. VD is pretty critical in construction, but has fewer itsy bitsy parts than VP, IMO.

A good F1D can bounce off the ceiling, walls, etc just fine if you have strong wing spars and posts. One that won't survive hitting the ceiling also isn't likely to survive steering. Definitely build a quarter motor dummy, though, as you gain a lot of information from quarter motor testing and can make many test flights in a fairly short flying session. You also waste less rubber when the quarter motors break. Whatever you do, don't let them break on the plane. It always involves carnage.

Good flying,
Joshua


--- In Indoor_Construction_at_yahoogroups.com, "mkirda@..." <mkirda@...> wrote:
>
> So I am starting with a Cesar Banks Novice Penny plane.
>
> I will initially be flying only in 20-40 feet range, so I am looking for recommendations for prop pitches.
>
> If I use the Propeller forming block Excel workbook, I enter in 12 inch diameter, 2" block thickness. Not sure what I should look at for desired P/D ratio. Maybe 2.0 or 2.2?
> Will be using some leftover pink foam, so I could do more than one rather easily - Just not sure what I should try first.
>
> I should probably already ask about F1D for the same flying spaces too, with simple non-VP props...
>
> Thanks in advance!
>
> Regards.
> Mike Kirda
>
Received on Fri Dec 16 2011 - 06:49:41 CET