Edge 540 - Angle of incidence

Edge 540 - Angle of incidence (Full Version)

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cosmospho -> Edge 540 - Angle of incidence (5/2/2008 8:43:05 AM)
Hello All, I have an Edge 540 from CMPRO and I am having a few problems with the plane.... The plane refuses to fly at any considerable speed, it flies very slowly like a shock flier, even with full throttle going down vertically it somehow breaks and is very draggy.... On takeoff it immediately leaps into the air, but drops the wing because it has no speed.... I cannot get the plane to pick up speed in any way.... Its currently with a 18x6 prop, which is not the best, maybe a 17x10 would be better, but still it does not make sense the extreme slow speed that it flies with the engine on full power over 9000rpm on a gas engine.... CG is set at 25 to 30%, been through nose heavy to almost unfliable tail heavy with no changes, besides the usual pitch/roll instability with tail heavy.... This afternoon I will test fly with some negative incidence on the wing.... Any thoughts ?? Too much positive incidence making the plane drag a lot when trying to fly straight ?? Its unbelievable, the plane flies slower then a trainer at full power, and when landing it drops from the sky like a brick on "Elevator" like manuever..... Thanks, Paulo

alan0899 -> RE: Edge 540 - Angle of incidence (5/2/2008 10:13:04 AM)
G'day Paulo, An 18x6 is not enough pitch, you don't mention what the engine is, I have a 17x10 on my OS160FX, so if it is something like that, 6" is not enough pitch, put more pitch on it, like a 17x10 or a 16x10, then trim it to fly straight & level at full power, land & check the amount of elevator angle you put in to get it to fly straight & level. There should be a very small amount of up elevator, if any, because your wings should be at 0 incidence , in relation to your tailplane,(horizontal stabiliser) as the yanks call it. I think it is just not flying fast enough with that prop.

cosmospho -> RE: Edge 540 - Angle of incidence (5/2/2008 10:58:44 AM)
Hi alan, The engine is a Brillelli 26GT Gas(petrol) engine.... I will try the 17x10 and give some feedback, somehow I still think something is out of wack in this airframe.... There is huge drag that cannot be accounted simply by prop.... Regards, Paulo

mjfrederick -> RE: Edge 540 - Angle of incidence (5/2/2008 10:00:29 PM)
You're tail-heavy, it's not the incidence of the wing (that could be part of it, but start by moving CG forward).

cosmospho -> RE: Edge 540 - Angle of incidence (5/5/2008 8:23:16 AM)
Hi Frederick, Its not CG related, I have moved CG way forward and way backward.... I can say its definately not CG, I have several other planes and know the effect of CG, this plane is simply not gaining speed, something is braking it in the air, either wrong incidence on wing, or wrong prop.... I spoke to some guys with Gas 25cc engines and they said that a 18x6 could be braking the plane too much.... I am waiting for an order of 17x10 props and will try again when they get here.... I have also changed the angle of incidence, so it will be new props and angle of incidence... If it does not improve then off with the engine and onto new airframe....

cosmospho -> RE: Edge 540 - Angle of incidence (5/26/2008 8:03:32 AM)
Some updates on the bird.... Took it out this weekend for 3 crazy flights.... Some more info on the plane, its 69" wingspan and weighs 11 pounds... I think this plane is too heavy for the wing, it handles great when flying really fast landings and take-offs are really wild, it snaps like crazy and I can't keep it on the ground long enough because it floats and then snaps.... I am going to give up on this one, as I don't want to destroy my new brillelli on a plane with poor aerodynamics or just too heavy to fly.... Its getting on the border of dangerous the take-offs and landings. Believe me its not tail heavy.... its has almost 3 pound engine on the nose.... Any ideas ?? do really heavy planes turn into this kind of brick ?? Sorry but I never had really on the limit weight planes.... Thanks

dick Hanson -> RE: Edge 540 - Angle of incidence (5/26/2008 3:08:04 PM)
Likely too heavy - and the low pitch prop will make it slower However incidence has NOTHING to do with speed -the wing will fly at what ever angle is needed for flight direction - you can't affect speed by relocating angle to fuselage you can change relative angle to stabilizer and screw up that working relationship - tho some so called tuning XSpurts will say otherwise - incidence angle establishes working angle (relative flight angles to the fuselage the stabilizer is THEN set for angle needed to provide best trim of the entire stab and elevator . This then provides required downforce- the braking (not breaking) effect of the prop is not an issue here .

cosmospho -> RE: Edge 540 - Angle of incidence (5/27/2008 7:23:12 AM)
Some updates.... Plane is on a diet plan, making swiss cheese out of all parts that do not affect structural integrity.... I have taken almost half a pound already and hopefully can take one pound in total.... I will test fly again tomorrow and if its back in one piece I will provide feedback.... I know the incidence of wing does not make much sense, but i thought if the incidence is wrong and I have to push/pull on elevator to make it fly straight it will make the wing go into different angle causing more drag.... I could also change my 14oz tank to something smaller since the gasser sucks less... Dieting on balsa planes sucks....

cosmospho -> RE: Edge 540 - Angle of incidence (5/29/2008 8:01:33 AM)
More updates... I flew yesterday with half a pound less and the plane was more manageable... Still has a few stalls and lands hot like a warbird, but I think the problem is the weight... I guess I need to shave a few more oz of this bird, wish it was that easy....

cosmospho -> RE: Edge 540 - Angle of incidence (6/2/2008 10:13:40 AM)
Flew again this weekend and after 1 pound of weight shaved off plane is a whole different beast..... Still snaps, but its an edge and that is expected, but it flies now like its on rails.... Great response, great wide loops and very nice all around.... I am happy.... Using a 17x8 APC prop, but will go to 17x10 wood for less weight when they arrive.... Its definately a lesson trying to shave off weight on a balsa plane where almost everything weighs next to nothing.... Thanks for all the responses and ideas....

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