Brian Taylor Me109E

Hi Klippy, would this be of help to you?

Martin, 3 of my models are BT designs, F6F-3 (64", converted from BT's -5), a Spitfire Mk1A (69"), and an 81" Mosquito. All are electric. They are set up for about 150 W/lb. All three use Turnigy motors from Hobby King. All are direct drive outrunners. The F6F-3 and Spitfire Mk1A use the same motor, Turnigy 50-65 270 KV. On these two props both 17" dia. APC's, the Mk1A has a 12 pitch, the Hellcat a 10. Both fighters weigh 10-11 lbs at take-off. Both use the same size batteries, 6 cell 5000 mah. ESC's are 80-85 A. Both are BEC equipped.

The Spitfire goes through about 14 amps ave, the F6F-3 about 20 for typical 8 minute flights. Both these amperage estimates are based on charge-back. Both planes could fly for substantially longer periods.

Mike

Hi Klippy, from what i can gather the estimated speed is about 50mph, again hope that helps

Mike

I am seeing a LOT of ply that could be taken out of those formers, and what is that inverted trangular lump of ply, only concerned about the weight that will be needed up front, lekky motos aint that heavy, the batteries could do some of the job as ballast, but i feel that at this size, reduction of rear end weight needs to be tackled, looks nice though, are you usung bellcranks, or servos, with direct drives? enclosed, or external pushrods?

LOL! Panic not Alan, that triangular lump is just something that i have placed the fus on, there are two more up front, just keeps it level when I'm doing things. Yep, yer correct about losing some more wood, job to do next week. Intend to use servos with direct drive and I want to enclose pushrods. I'm on hol next week so hope to get the girl to lose some weight

make up a elevator joiner, with a central tiller arm, push rod straight down the fuzz, 3mm rod, easy peezy, closed loop the rudder, and put another link to the tail-wheel, although i prefare a fixed wheel on my warbirds,

Ok Solo, dropped the ball here, I'll be posting the new math tonight.

many thanks Klippy, appreciate greatly the advice, starting to remove as much wood from the girl this week, see how it goes.

Mike

Think twice cut once is the rule here Mike. Dont sacrifice strength for lightness, its easy to go too far, and weaken key areas.

Garry

Isn't it funny, we fly RC but we really don't have very much idea how fast they're going! Let's say that max speed will be 70mph, that's 70/60 miles per minute = 1.167mpm. Change that to feet 1.167 x 5280 = 6160'/min times 12 to inches = 6160 x 12 = 73,920"/min now divide by our maximum available rpm 73,920 / 6049 = 12.2" pitch

As long as the model goes forwards when facing into the wind, who cares? :lol:
It's when you have the throttle wide open, and the plane is still reversing down the field, that you need to worry! :evil: :ohmy:

Technically, it is an interesting topic, but the limiting factor will always be the ability of the nut holding the transmitter! :S

Klipkopwildlife wrote: Isn't it funny, we fly RC but we really don't have very much idea how fast they're going! Let's say that max speed will be 70mph, that's 70/60 miles per minute = 1.167mpm. Change that to feet 1.167 x 5280 = 6160'/min times 12 to inches = 6160 x 12 = 73,920"/min now divide by our maximum available rpm 73,920 / 6049 = 12.2" pitch

Dont you just hate a smarty pants :lol: :lol: Well thought out, and well explained Kippy. Thanks for that

Garry

I've been playing around based on some of the numbers that Solo gave us and came up with this


Note that this setup of 2 x 4s Lipos in series weighs a total of 1,593g for 176W/lb using a 20 x 8 prop. Note the massive static thrust of over 7Kg! However I think the maximum available speed might be a little low.

In my humble 'little plane' world for a given power I tend to think of an 8x4 as a fine pitch prop and an 7x6 for speed.
As planes get bigger the engines (or motors) rev slower for a given power level so the pitch to diameter ratio tends to be higher rather than lower.
So far an aerodynamically slippery Bf109 my guess would be a pitch of at least 75% of the diameter so with that sort of ratio identify the biggest prop the motor can safely swing within its maximum current limit.

I happen to know the Fokker Triplane had a 8' 7" diam x 7' 6" pitch prop. :ohmy:

I will now go back to cutting some Depron!

I thought I'd run Solo's current setup for his Spit on ecalc and got this.


Note that you only have 2.5Kg of thrust when stationary, a drive line weight of 1.45Kg and only 70W/lb!

And this is the one for the Hellcat


Note how the watts are even lower, and look at the speed!