F2B engine size

[Phantom805]

Hi,
     
I recently bought a F2B stunt model and would like some advice on the engine size. The model is 60inch (1.5m) wingspan and weighs 2.6lb (1.2kg) (without engine). The previous owner had a 56 Saito four stroke in it. I am not into four strokes and I have an OS 40FP that seems to be similar horsepower to the     Saito. However, a 40 sized engine seems rather small for a model of this size.           
                                                     
Any advice would be much appreciated.

[Gerald Arana]

I think I'd want at LEAST a 46 and preferable a 60 in it. Maybe even one of those new 75's Randy is peddling. Got bucks?

Good luck, Jerry

[Tim Wescott]

A 40FP would probably be too mild.  I have a plane of similar dimensions that's working well with a 46LA.  Don't put too big a prop on it.  I do not have personal experience with them, but a piped engine that's known to work well for stunt would do.  There are some piped 40s that would probably work just fine, but I don't think that a 40FP, even on a pipe, would be one of them.

[Steve Helmick]

Hmmmm. 2.6 lbs=41.6 oz. Add 15 oz for tank, prop, engine, spinner, fuel filter...56.6 oz.  The 60" span doesn't tell us much, with what appears to be a highly tapered wing. Could you figure out the wing area in sq. inches, including that inside the fuselage?

Looks like you're in England, so some windy weather. I'd first suggest a ST G.51 with the Brian Gardner ABC kit, Rustler-Belko (RB) .61, an old Merco .61, an ASP XLS .52, or some Enya and OS products. I'm not into 4c's either, but you need something with some weight and also fuel economy, to avoid severe balance and tank capacity problems. You'll probably need 6 oz fuel tank capacity for most 2c glow engines or possibly more. If you were willing to run a diesel...the PAW .40 should do.  I'd also suggest contacting Andrew Tinsley for some local suggestions. Look 'im up in the Members list under "A".  Cheers!    Steve

 

[Air Ministry .]

A 40FP can be fairly useless with runnaways , I used a CLONE magnum , in a 2 kilo thing.
11 x 5 prop , Id Drilled the straight thru intake to 1/4 for 1000 Alt hot air .
Sea Level in NZ it did 500.000 mph ( or thereabouts ) and needed the 1/8 venturie .

Id check the MOUNTS and go with something that fits the bolt holes & matches the weight .

If your just clowning the FP'd be o.k. , Deadly Serious the $ Stroke might be the go .

[Phantom805]

Hi guys,

Thank you for the detailed responses. The  wing area is 418sq inches. The wing tapers from 2.5inches at the root to 1inch at the tip.
                                                 
Do you have any experience of running ballraced engines for control line? I have always used plain bearing engines on a 4 2 4 mixture. It seems quite tricky to get hold of plain bearing engines of that size. I have an ASP 61 but that is ballraced and quite a heavy engine.

You are right I am in England so I definitely need enough line tension to handle the British weather!             

There is enough space for an electric drive train if anyone has any suggestions on that front.

Thanks again.

[Phantom805]

Sorry make that 836sq inches. I forgot the other half of the wing!

[Mike Scholtes]

I don't know what you've really got there, but the photo indicates the fuselage is snapped at the wing TE, the flaps are tiny, the stab/elevator seems very small for the wing size, and the model looks generally beat up. Not to be too pessimistic, but you may be better off to flog this one at the next swap meet and get a modern, normal-dimensioned stunter with a proven design. The model looks like it may be an RC conversion, or a one-off design. I am also skeptical the wing area is over 800 inches with a 60 inch span and significant taper. How about a Brodak P40 or something that is available in the UK (if that is where you are, judging from the price on the wing)? I see a lot of headaches in the future with this one.

[Lauri Malila]

The proportions look like from Beringers & Delabarde school, France. This type of design has won a couple of European champs and World champs, last time in 2006. They used Saito .56.
But to perform well it needs to be rather light. L