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Quote: Originally Posted by fdo300 |
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Hi
I need a little help from you guys, Kiwi's superXtra (old style) is on overhaul right now!!!! a little history fist....... 2 servos per elevator and and ZDZ 160 w/regular muffler in front= tail heavy !!!!.
To get the a decent CG for Imac sequence we had to put 4 lb on the engine dome, then if you want to fly 3D another 1/2 lb on the tail wheel and the wing in forward position. We tested it for about 20 flights, Sequence are perfect but 3D, even with the lead on the tailwheel, is terrible.
So we removed all the lead and the CG it's now 150 mm back on the wingtip with the wings on backward position (IMAC). Now sequence are suck and 3D is much better.
Any of you guys who have one of this SuperXtra can give us some info about CG and specially engine/wings/elevator incidences ??
Regards
Fernando Viollier C.
GSA Sales Manager
Tel: (56-2) 7471224
Cel 56-9)843-0510
www.giantscaleaviation.com |
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Fernando.... I have been flying IMAC for 3 years in Unlimited with my Super Extra (774 flights)...so I think I should know something about these planes.
The first thing is that the wing & stab incidences have to be set properly. Where the canopy sits, is not actually level with the thrust line but you can go from there.
Start by levelling the aircraft front to back & also side to side. The wing incidence should be (Negative) -0.5° meaning that when the aircraft is showing level on the canopy rail, the wings should be half of a degree negative. From there, measure so that the stabs are + 0.7° or 0.7 of a degree positive to the wings. This will give you what I have on my aircraft.
My wings are in the back position as I did not like how it flew IMAC precision in the front position. My balance point right now with the wings in the back position is 5 3/8" from the leading edge of the wing tip. I fly with a DA 150 & MTW cannister mufflers. I did not have to add any weight up front at all to balance where I am now. I am using a Tru-Turn solid back-plate spinner, but that is the only weight I have up front. I do have only ONE 8611A on each side of the elevator as opposed to the two that you have. Two will definitely require you to put weight in the front, but "4 lbs"????? That seems way out of line to me.
The engine needs up thrust, I think I started at 0.5° (½° up) & added what was needed in very thin shims until I got it where I wanted it.
The power-box batteries are located on the tray right beside the fuel tank, & the ignition battery is up front to the left of the firewall & strapped to the inside of the fuselage.
I am not a 3D expert, but the airplane allows me to do Knife-Edge loops, K/Edge spins, Harrier rolls, Harriers, (semi)T/rolls & quite a bit more stuff with the Super Extra "as is"...without having to move anything at all.
It seems to me that you need to go back to square one & start from scratch to get everything right. It certainly is a great flying airplane.
Wayne
Sew Busy
http://www.sewbusy.com