Kevin23

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I have searched with no luck,I am looking for some info on what engine will power the nitro planes 56" yak with great power!
I picked this plane up from a friend that had a fl70 in this plane and it was a pig.
np says this plane is for a 70 fs,don't know if my friends motor was sick or does this bird require a bigger fs or just put a 2 stroke in it?
I was going to put my saito 100 in it,but it seems a little big for this plane,the valve cover completely sticks outside the cowl.
weight wise it is roughly the same as the 70 that was in it,it is just a lot taller engine.
so was thinking either the 55ax or a saito 72 or 82.
thanks for any help,
Kevin

nitro wing

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The 3 listed motors are all good choices.It is a bad engine or a bad tune, bad prop combination, if they wont work extremely well.

Kevin23

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is the 100 just overkill,or is it ok with some throttle management?

thanks for the info

nitro wing

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Sure you can jam it in there,it will be just heavy and nose heavy and fragile and probably wreck the landing gear and blow the tail off,which apparently is weak at the joiner,some of the glue joints will probably fail and the wing spars will rattle out.It will land like a 104 Jet and take off like one.The covering may blow off at the seams.Glide ratio and low power flight will look much like a space shuttle returning from space.
Seriously though,this Yak would fly best on a YS 63 or Saito 72 or OS 55AX and a small flightpack.Those motors will easily take care of the Yak unless it comes in way overweight.
Remember,for 3D you need ultra lite weight wing loading and good power
not excessive power and a high wingloading.Good luck.
For true 3D this model may not really work that well.
one or 2 or 3 ounces make big differnces in performance in an airframe of this size.

Kevin23

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thank you,i think i'll try the 55 first,keep it light.
the saito 100 only weighs about 2 ounces more than the fl70 that was in it.
the surpass 70 weighs more than the saito if the weights on tower is accurate
thanks again for the help,
Kevin

XJet

Why not split the difference and go for a Saito 82. It's got measurably more power than a 72 with no weight penalty at all.

And to anyone who's worried about the effects of extra power -- well if you look closely at your transmitter, you'll notice that one of the sticks doesn't center by itself. It just goes up and down with a slightly ratchety or sometimes smooth feeling. That is what we experienced 3D fliers call the *throttle*. It may sound a bit far-fetched, but by moving that stick you can actually make an 82-sized motor put out exactly the same amount of power as a much smaller engine.

That's right -- it's not just a "landing switch" that changes from full-throttle to idle -- it's actually a way of changing your engine from a fire-breathing .82 to a quiet, gentle .049.

But seriously, I think the Saito 100 would be too big, for the reasons stated (fragility of the airframe and weigtht). Although it's only a couple of ounces heavier than the 72/82 on paper, you have to remember that it will need a bigger (ie: heavier) prop (there goes another couple of ounces) plus a bigger tank (at least 2-4oz of extra fuel) and then your CG will be too far forwards. Even jiggling y our battery position around probably won't help so you'll need to throw some lead in the tail. Before you know it you're heading towards an extra half-pound of weight in what is a pretty small plane to start with.

The Saito 100 will also shake like a jackhammer until its well and truly broken in. I don't know if the Yak is up to the task of withstanding that kind of punishment.

Get a Saito 82 (they're a much better motor than the 72 for only a small premium in price) or an OS 55AX. Either of these will haul that Yak around so fast that the tailplane will fly off (yes, it happens) unless you're *very* judicious in your use of the throttle. Remember -- it's *not* a pylon racer :-)

Kevin23

My Feedback: (4)

I love your sense of humor
I am one that fly's pretty slow and have really focused on learning the 3d stuff.
I used to fly balls to the wall,but have calmed down.
this plane was just purchased 2 weeks ago,and is "supposed" to be the new batch with the reinforced stab,the elevator stab looks and feels to be very rigid and of good build quality.
the elevator halves and stab are the same thickness,I have seen where this has not been the case.
I hope it holds up well.

nitro wing

My Feedback: (1)

Forgot about the 82,the 55 should be an easy fit,unless it has an awkward exhaust.Do you have any of these handy or are you buying a new one?
You may need a pitt style muffler for the 55

-StephenSampson-

not to big at all...i know people who had saito 100 in funtana S40 powerhouse....unlimited vert....lots of fun.....just fiberglass the firewall and the sides around it before you put anything up there....i do that to all my plaens anyway.....saves time if theres problems later by eliminating the possibility earlier.

nitro wing

My Feedback: (1)

Yeah.. I put an OS 91FS and lead in the tail on the .40 Funtana,total Pig.
Vertical? Hover? Pullout? Short take off? Sure. Who cares
Good proper precision 3D is often at or below stall speed,on a light wing.
This has been thoroughly discussed over the years.If you are a bank and yank type of guy and think hovering is 3D,then giv'er.
If you actually want to improve your skills and fly like some of the top pilots,then take everything into consideration and build accordingly.

Kevin23

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I got lucky,a friend happen to have a new surpass 70 I picked up and installed it in the bird this evening,will fly it tommorow and see how it does.
I can use this on another plane if it doesn't have enough power,and i'll get either the 82 saito or the 55ax for it.
with the rudder servo in the tail,had to install battery at cg to balance where the book said to balance at 120mm

nitro wing

My Feedback: (1)

The OS 70 is not that powerful,but with the right fuel,at least 20% and a good balanced prop it should do the trick for now.
Put an APC prop on it,dont go with some inefficient blades.

Kevin23

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apc 13x6 prop wildcat 15% heli fuel,the plane flew good,not unlimited vertical,but enough power to fly the plane real good,was too windy to fly it much.
didn't try to hover,but the vertical uplines were good even with the wind as bad as it was.
nosed in the wind with the throttle about 1/4 stick the plane was flying backwards[X(]
it was getting tossed around a good bit,only put it up once,didn't want to push my luck

Kevin23

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I am wondering any one that has this bird what you wound up running the cg at?
it is on the wing tube right now per the manual.
seemed to fly kinda nose heavy,was hoping it would be safe to move it back a little with out it getting stupid on me?

nitro wing

My Feedback: (1)

Just go back 1/4 inch at a time.
I fly an EF Yak and moved the CG back over the weeks.Now it is a total animal,but still behaves well.Does it fly well with neutral trims?,if not ,an incidence check wouldnt hurt either.

Kevin23

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does good with neutral trims,it fly's better than I would have thought to be just a 40 size,usually not as stable as this guy,but it is flying a little front heavy