KZig

Hello all and thanks for coming to this post first off! I'm building a Sig 3D Mayhem and have gotten as far as bonding the wing halves together using epoxy. I want to ask if anyone here has built and flown this plane that may have some good tips or changes they made to this aircraft that they would care to share. I've gotten some really good tips from "dhammer" on engine selection and thus am going to be using a new Saito 1.50 for power. ( I fly at 5,500 ft) My biggest concern is getting the wing and stabilizer in sync with the engine thrust. Do any of you use a wing incidence meter when building or do you just use your sight and measure before gluing? Since this is an ARF, I would assume everything should be pretty much on... just need gluing together.

I built a GP Extra 300S a few years ago and had a YS .91 on it. I liked the plane, but if you were just cruising around at half throttle and then went to full throttle the darn plane would just climb, climb and climb until you either gave it down elevator trim or throttle back. Why is that? I kept putting washers on the engine mount to give it more down thrust, but even that didn't work! What did I do wrong in building and how can I prevent that from happening on this plane. I do understand that the Mayhem is not build for speed at all. I just want a plane that when flying level real slow and then given a bit of throttle won't climb all the sudden without first applying up elevator.

Thanks for the help!

KZig

Barry Cazier

My Feedback: (17)

This is a great airplane. I have one with a YS110. It is my favorite. It'll land so slow you won't believe it and will do any 3D imaginable. I moved the rudder servo to the back of the plane and did away with the pull/pull design. I built it just like the manual other than that. When I got completely done mine weighed 7lbs 14oz. I try to keep my planes as light as possible. Also I was very impressed with the quality of this plane, except the axles. I had an axle break on my forth of fifth flight. No hard landings or anything, just broke during flight. I was able to harrier land it because it lands so slow without any damage. Lesson learned: replace the axles before you fly this plane! I used a HiTec 5645 servo on rudder and elevator. I used HiTech 645 on ailerons. These are fairly high torque servos but I think it helps with control and helps to reduce flutter. There is a fairly long thread by "airplanenuts" somewhere on RCU with quite a few building tips. Hopefully you can find it through the search engine. You'll really like this plane. I think it is really one of RC's hidden beauties. I enjoy mine.
Thanks.
Barry

Rixter

Hi Barry,
Good luck with your Mayhem. Sig usually markets good stuff. In response to your question concerning the throttle induced pitch changes in your Extra, perhaps it was nose heavy. If a nose heavy model is trimmed out for level flight at half throttle it will climb at full throttle. This is because it takes more up elevator (on a nose heavy model) to produce the required angle of attack (and lift) at the slower speed than at the faster speed. A well balanced aerobatic model like your Extra, when trimmed for level flight and then rolled inverted should require very little, if any, down elevator to maintain level flight. Since no two aircraft are ever built exactly the same the Mfg. suggested CG should be considered a starting point. It is up to you to trim out the plane. The NSRCA has a nice trimming chart here [link]http://www.nsrca.org/trimA.htm[/link]. Hope this helps.
Rick