I need help with understanding how the servo is tied to the horn on the bottom wing. The instructions talk about a tri horn that i don't see in the kit. What am i missing for this Ulitmate 120 Nitro plane? or is there a process of doing it i dont understand. Also I plan on putting in a 1.20 two stroke engine, which I hope has enough power.

Thanks

There is no "Tri horn"... it is just the standard control surface horn that is supplied.

You install one on the underside of the top wing, and on top of the lower wing, then connect the two via a pushrod, so that the one lower wing servo effectively drives both control surfaces.

This is NOT the optimal way of doing it on bi-planes, but after comparing the "proper" technique against this much easier installation in flight, I see little difference on this size plane.

The "proper" technique would involve cutting the control surface and installing a specially made horn ( something YOU must fabricate ) so that the interconnecting pushrods are connected at the trailing edge of the control surface. This moves both surfaces an almost exactly equal amount when deflected by the servos.

It works great but I do not recommend doing this for people with little ARF experience.

A 1.20 two stroke will more than adecuately OVERPOWER the plane. The plane was designed for a 1.20 FOUR STROKE engine.

Your 1.20 two stroke will be the equivalent of installing a 1.60-1.80 four stroke in terms of power.

Since the two stroker spins faster than a four stroker, consider choosing a prop of a diameter on the higher end of the range recommended props for your engine, and going with a lower pitch... I'd say a 6 pitch prop will be fine and I'd even consider a 4W pattern prop to let you slow the plane down for landings.

OPJOSE,

Thanks for the feedback and I will do just that. I plan on using DAROCK concept for for installing the the linkage for attaching the upper and lower alerions.

Also, has anyone used the single servo approach for the rudder versus using dual servos (I would attach the elevators together by using a rod)? I am using the Futaba S3010 servos, 6V battery, and was wonder if the single servo approach would work?

Thanks

Thanks for jogging my memory... DaRock's approach is what I was thinking of.

Yup that's the "proper" way of doing it.

Re: Servos

The rudder and elevator only use one servo if I recall correctly.

CF pushrods are used to connect the two elevators to the single servo under the canopy and also for the rudder.


That is on the 1.20 size. The 50cc size ( which I also own ) uses individual servos for the elevator halves and one servo for the rudder.

CF push rods means?

Also, for my understanding is that I would attached the bottom wing alerion to the servo as normal, then incorporate DAROCKS concept..correct?

Sorry for asking

CF = Carbon Fiber

There are two included in the kit, one for the elevators and another for the rudder. You'll also find rod ends, berg screws, clevises and metal rods to assemble the pushrods.

Re: DaRock.

Correct.

The bottom servo drives both control surfaces via the interconnecting rod.