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Model Forum / General / Models / March 2008Blackhorse Travel Air
I have recently purchased a Blackhorse Travel Air and need to know the location of the c of g on this plane as I have lost the instruction manual. Are there any other things that I should look our for on this plane? What prop should I be using? I have a OS 46LA fitted currently. I am new to this hobby, so would be pleased with any guidance given. Thanks, Chris I don't have the details of the exact plane in question but as a general rule of thumb - if it is a built-up wing then CofG is usually on the main spar - if foam wing then CofG will be between 25% and 33% of the wing cord from the leading edge Having the CofG slightly forward is safer than have it backwards. With it forward, the plane will fly stable but will will feel nose heavy. With it backward, the plane will be unstable, wanting to pitch up and stall. Cheers, Nigel . > Having the CofG slightly forward is safer than have it backwards. With it > forward, the plane will fly stable but will will feel nose heavy. With it > backward, the plane will be unstable, wanting to pitch up and stall. Nigel, Don't you have this backwards ? If the CG is to the rear, then the nose is heavy ... and this is a better thing than the reverse ? ie: CG forward = tail heavy. Slightly nose heavy is a safer condition when it stalls. Bill No I haven't. I'm assuming that you balance the plane at the CoG. If you balance the CoG forward then you need more weight on the nose which is safe. If you balance the CoG backwards then you are putting weight on the tail which is bad. So it is safer to have the CoG forward of the designed position. It might be that we are both saying the same thing but from different perspectives. Cheers, Nigel > No I haven't. > [quoted text clipped - 9 lines] > Cheers, > I think he's talking about a real aircraft here, not a model. If that's the case, then he needs specific information regarding how the aircraft will react with its position of CG in flight. Assuming that, he really does need the Pilot's Flight Manual in regards to how the aircraft should be loaded and balanced to fly safely, as every aircraft is different in that regard. In the case of a static model, all we need to do is get enough lead in the nose to make it sit right on its nose gear. In RC models CG makes a difference in regards to flight characteristics, but who ever started describing the specific propeller on a RC aircraft in regards to its flight characteristics? Pat >> No I haven't. >> [quoted text clipped - 24 lines] > > Pat I think he's talking about one of these - http://www.flyingsites.co.uk/reviews/travelair.htm General rule of thumb for balancing out an R/C aircraft is to put the CG at about 1/3 chord - i.e.: balance the model about 1/3 of the distance aft of the leading edge of the wing. This being a straight wing monoplane, that should be ok for starters - balance it with the fuel tank empty so as to get a slightly forward CG when fueled, and note how much pitch trim authority your servo system gives you. As to props - props are spec'd by diameter and pitch - for this particular one, I'd suggest something about 10 inch, maybe with a 6 or 7 pitch - 10x6 or 10x7 then, maybe an 11/6 depending on how the plane sits on it's gear, and noting that a 10 might be a little on the small side for a .46 engine. 6 pitch is a pretty good start for a general purpose all around fun flying. Heh...I'm a pretty good guesser, I guess...turns out OS recommends an 11x6 or 11x7 for your motor - http://www.osengines.com/engines/la.html If you do end up having to use the smaller diameter, be aware that your engine will rev higher and you may need to watch it with the throttle.  Signature- Rufus At no point was I (or I beleive anyone else) talking about static models. I was well aware that the OP was talking about a RC aircraft and gave advice appropriately. I stand by the general rule of thumb for RC aircraft - balance on the main spar if there is one - if not then balance somewhere between 25% and 33% from the leading edge Most RC plan plans show a small range of balance points - forward for more stable docile flying and rearward for more sensitive aerobatic flying This is why I recommended that a beginner should balance at the forward part of the CoG range. Cheers, Nigel > I think he's talking about a real aircraft here, not a model. > If that's the case, then he needs specific information regarding how the > aircraft will react with its position of CG in flight. No, he means this: http://www.americanpioneerhobbies.com/travelair_dragger.html and I'd be surprised if the company didn't send him at least a photocopy of the manual upon request. I thought the thread was about this: http://www.aviation-history.com/travelair/6000b-1.htm and why I have to make it as a vac-form or scratchbuilt has always been a puzzle. They didn't call it the Golden Age for nothing. |
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