hello all....need some input please....

i have posted this question already in another previous thread, but perhaps it's not getting noticed...i am in the process of assembling the flip 3D and seriously considering going with pull pull for the rudder and mounting the servo in the cockpit just about on the c.g. this would allow me to do away with that "torque rod" for the split elevators (too much flex with that set-up with prior planes with not near the surface area, not too mention the ease of elimination any differential that may be encountered) and use the existing rear mounted servos for each side of the elevator..however after stretching string in the approximate location of the pull pull cables, they will exit the fuse sides about 12 to 14 inches from the rudder control horn....my question is, for any of you with pull pull experience....by having this much cable exposed outside the fuse will this cause problems such as flutter, etc.....
thanks

I'd think as long as you do not have a lot of slack, it should be fine.

I not sure if this will help, But I use pull-pull on all my planes. The only thing is, is that I fly just WW1 planes !/4 and 1/3 scale and never had any problems with flutter. I have heard that some do use the pull-pull on 3d planes with no problems.

I have 12" of cable out side on my 3D modified Kyosho Majestics X2 of them. Power is )S 70 four strokes and there is no problem with having that ammount of cable out side of the fuselage. I have flown both of them for 12 months each weekend buring at least 1 to 1.5 gallons of fuel each time I go out for the day.

My question to you would be, " what would be the difference if there was a lot of cable outside of the airframe? Afterall there is at least 22" of cable on the inside > ? ? ? ?? ? ?

As long as you have the cables tight as with any pull pull system, then there is never going to be a problem.

As a point of fact, on my 37% Aeroworks Extra there is a whopping 26" of cable on the outside !!!!!!!

Have a good time with the Flip

Cheers for now,

thanks for that info.....the only problem i figured i would have would be flutter from the cable....i have used pull pull systems several times but i have never had near this much of the cable exposed to the outside of the plane...my plan on using this set-up is a big deviation from the way the manual shows, but i feel this would be a good move, i hate them split elevator "torque rod" hook-ups...i considered going with the mk bellcrank and using the set-up as is, with one elevator servo...but the reinforcement needed would be more than what i would want to do...

I believe he is worried about flutter due to vibration of the cables from the airflow around them. This would not affect the 22" inside the airframe...unless there is a hole somewhere.

Hi,

You can also cross the cables inside the fuse. The left side on the servo arm pulling the right rudder horn. This might cause less cable to be exposed (looks so much better )

Just a thought....

Later

Willem

i have never seen a pull-pull on a rudder where it is attached in the middle like that

Hi Shortman,

The reason the cables are like that are as follows.

1. The elevators move up to 40 - 50 degrees so the horn has to be this far up the rudder. If you notice the elevators are 1.5 inches wider that the standard and the stab is cut back narrower. This is to allow for much better 3D work in the air with the elevators gaining 70% more area, thus better authority, without any change in overal combined surface area of the stab and elevator combined.

2. the direct line to the servo is kept direct, thus this is the route.

3. The fuslage at this point is very slim so this is the point of exit.

Anyway, altough it might look a bit unconventional, this route has no binding what so ever (direct servo to horn link) and having flown my majestics for a year with this mod, I can only say that it works a treat.

cheers,

well first of all thanks for all the input on this....i am sure i will go with this plan....now i just need to look for a arm or wheel for the servo....i have already ordered the aluminum control horns needed from c-hobbies....i am looking at the hanger 9 wheels they make 3 sizes..thinking the medium may be one...not sure on how that cable attaches to the wheel? is it a special cable they are using with them?.....don't have a full aluminum arm only half arms for the other surfaces...i know nelson makes some offset tillers but i don't think that will be needed......

i feel that this is a good change...getting rid of that split elevator with a single servo....i think with the control surfaces this large that there would be too much flexing between the two...am i thinking right or is this "over doing it" ??????

Hello,guys does someone know why do some people(Pattern,Imac pilots) use an aluminum servo wheel(ARM) on the rudder servo instead of a normal servo arm,with pull pull instalations,is it because it`s lighter or just prettier,is there a real advantage in using one .thanks for the help.

i have never used the wheels....but i can see an advantage as far as the geometry goes on the servo end..it stays the same....and if you connect on the hinge line on the control surface that is the perfect configuration.....i am looking at the hanger 9 medium sized wheel for my application, but from looking at the pic on horizons site i still can't figure out how the cable attaches to it.....