RE: RE: RE: OMP Yak build
 

The magnum is working out great. I flew it 3 more flights staurday and while it was pretty windy I got compliments on KE harriers. Doesnt TR easily in the wind though. Those big wings just catch too much air. My CG was about 1 to 1-1/4 back If I remember correctly with the motor about a 1/4" from the end, battery in stock location, doesnt fly tail heavy at all, In fact inverted still requires the occasional touch of down. Flat spins are perfectly flat and stationary now that Ive learned a little more about it's habits. Harriers still pretty rocky but like I said it's been windy lately. I used a radical RC integrated charge switch (mpi would also work and is a tad smaller) and just cut a slot into the top of the fuse to fit it in, drilled a small hole thru the foam so the wires would come out in the battery compartment

RE: RE: RE: OMP Yak build
 

M Grambling,

The plans show the CG 3/4" behind the rear edge of the tube or 1 1/8" from the center of the tube. This is a conservative starting point and probably nose heavy for most 3d flyers. I've got mine balanced so that it's hands off rightside up and inverted. The rx is in stock location and the battery is mounted in a hatch between the le and wing tube. No additional weight anywhere and have a OS 91 with stock muffler up front. I will check the exact CG location and post here tonight.

Mike

RE: RE: RE: OMP Yak build
 

Being the Saito 100 is 4-6 ounces lighter then the OS 91 sounds like I might be moving it to the nose.

RE: RE: RE: RE: OMP Yak build
 

thanks for everybodys hellp on the CG. I was worried, about the CG. Because I really didn't want to add 5oz to the nose of this bird. I new people were flying it with a 91FX but didn't know where their CG was coming out at.

Hopefully I will finish it up this week and fly it on thursday.

RE: OMP Yak build
 

Well its almost complete, The fuse is covered all except the cockpit, I'm almost ready to take some pictures.

One thing that I need help with is the tail wheel. I thought I had one that would work in my inventory but after looking this morning I found that I had none.

My question now is what's a good tailwheel assembly for this plane?

Thanks
Blackie

RE: OMP Yak build
 

I bought one of those Sullivan tailwheels for mine. It seems to be a pretty sturdy unit. It connects to the rudders with a spring, and comes with two different size ones so you cna adjust the tightness of the link.

I'm about 75% done with the covering on mine, too. Need to do the fuse, one elevator, finish the bottom of one wing, and the rudder. Still waiting on the engine. Aparently, it takes a money order longer to get from Fla to New Mexico than I thought.

RE: OMP Yak build
 

I used the sullivan tailwheel bracket as well, with the lightweight foamy 1" tire.. dubro I think

RE: OMP Yak build
 

Yep, the sullivan bracket is very popular back here at OMP as well. Bolts nicely to the hardwood plate at the back and the spring attachment to the rudder works well to keep stress of landings off the rudder.

Mike

RE: RE: RE: RE: OMP Yak build
 

Well, I am going to fly mine tomorrow. I will let everybody know how it flys. I got my OS91FX running with the moosecan I built. It swinging a 15x4W APC peaking out at 11,300RPM. I got it set to run at 10,900. Man that thing is a powerhouse. I think it will it shoot it out of a hover. Hopefully tomorrow, I can tell.

RE: RE: RE: RE: OMP Yak build
 

Boy so many of you finishing up so fast. Some of us have to work for a living. :) I'll be pushing it to have mine ready by this weekend.

RE: OMP Yak build
 

The bad part is, I could have mine done for the weekend, but I won't get a chance to fly it for another three weeks. Going to visit the parents this weekend, and my son has a competition at school next weekend, plus a wedding to go to. Looks like April before I get to try it out.

RE: OMP Yak build
 

Ok I was reluctant to ask this but I have a question on CG. Does this plane CG inverted or right side up?

RE: OMP Yak build
 

since it is a mid wing, I balanced mine right side up

RE: OMP Yak build
 

I flew mine today. My 91FX and moosecan wasn't running right for the first few flights.. the first 3 flights ended in dead sticks. but this thing will glide for a while. it flys like its real light weight. I haven't found a prop yet that I like for it. A 15x4W APC pullout wasn't great, it had to pick up speed. A 14x6APC wasn't good either. I like a 15x6MA wood, spool up is great, but something is lacking. I forgot to bring my 14x6MA wood. but that is probably what I will like for getting out of a hover. Hopefully the 14x6MA Wood will rocket me out of a hover. PaulSwanny is running a 14x6MA wood on his ST90 and moosecan on a .60size sudukio that weighs 7-3/4lbs and his pulls out great. In matter of fact his pulls out better than mine. so next time I fly it I will try the 14x6MA wood.

My CG was set at 1-1/4"from the wing tube with a 15x4W.. And plane flew great upright and inverted. Just very small amount of down to keep it flying level when inverted. but when I put on the 15x6MA wood,it pushed my CG a little past the 1-1/4"mark. And it would climb a little inverted. So I wouldn't go any further than 1-1/4" back. Also when the tank is low on gas, to land it you have to give it a tad bit of down, to land it. but isn't not bad at all. With the CG back a little to far, it will easy inverted harriers. Because the nose was to climb, all you have to do is control the throttle, to keep it fromdropping or climbing. also it will do the tightest walls I have seen in a while. It will pop the nose up faster than my .40sledge.

Also the elevator is real effective, I had to crank up my expo to 40% on low and high rates because is got a little pitch sensitive when the CG back a little to far.

so if anybody is flying this plane with a OS91, or similiar 2-stroke, canyou tell me what prop your prefer on this plane.

RE: OMP Yak build
 

i was told by several people to use an APC 17-6 on the ys 110, that was too much prop. It pulled fine but was really lugging, now im using a 16-8 and its much better but i think a 16-6 will be perfect

RE: OMP Yak build
 

As of right now, I am happy with the way the plane flys. but power wise I feel I am lacking. I don't see how you could have much fun hanging on the prop with anything less than a 91-2stroke. Maybe after I swap props to a 14x6MA wood, maybe I will be happier with the vertical performance.

But I have been flying a Sledge that weights less than 4.5lbs with a YS63. The vertical on it is awesome. I would love to have The OMP YAK set up the same way on pulling power.

Since the YS110 4-stroke is a power house. I think you could get away with a 1.20size 2-stroke as well.

If your flying this plane with a .90size 2stroke let me know what prop you like. So I can try it.

RE: OMP Yak build
 

Well I like the 15-4 apcW on my magnum 91 XLS but it does take a 1/2-1 second or so to spool up to really pull out of a hover strong. I have allways used a zinger pro 14-6 on my ecstacy with an OS 91 fx and have loved that prop on it, very fast spin up but not quite as thrusty as the APC 15-4. I may try it this afternoon on my yak to see the difference. I too have the 40 size edge with a saito 72 and this setup does not match that, but I didnt expect it would. You would need a 110-120 4 stroke to match that kind of pullout, but then your weight would go up as well. I flew the a different yak with an OS 120 4 stroke and even it didnt have the pullout my ohio 40 size edge with the saito 72, bigger plane more weight, more drag. A 35% with a da100 overpowered 2-1 doesnt pull out as well as my lil edge

RE: OMP Yak build
 

With my Saito 100 I'll be using a 15X6.

Blackie

RE: OMP Yak build
 

Without a doubt, the best prop for the OS .91 is the new APC 16-4 fun fly wide blade prop. I switched to that and it's awesome for 3D. Good throttle response and no air cavitation at all during hovers or tailslides.

Mike Pilkenton

RE: OMP Yak build
 

Forget the zinger pro 14-6. pullout was anemic. The apc 15-4 wide is night and day better on my mag xls 91.
AF you sure you maen 16-4, seems like a heck of a lot of prop for a 91 2 stroke. I would think spool up would be pretty slow, although Im sure it would have tons of pull power once up to speed

RE: OMP Yak build
 

ive built a yak 54 profile form omp i have a xls 91 and hitec 605 servos im just waiting for the weather to warm up to try it (you can see a picture on my gallery) has any one found the best cg point for these ?

RE: OMP Yak build
 

I can't see how a 16x4W APC would do any good on a 91size 2 stroke. I think it would have tons of airflow over the tail, but pull out be lacking due to the long spool up time and load.

What do you think a 14x4WAPC would do, it would give you more quicker spool up time, because the prop is smaller, and also a little lighter weight. but I don't know how vertical performance would be. the next time I fly it, I am going to fly it a few times with my 15x6 wood on it. then compair swap to a 14x6MA wood. then swap to a 14x4W APC and see which one I like. I might even bump up the nitro to YS 20/20 and see if that helps my vertical. I think maybe a 15x5 Prozinger (if they make one) would be great. It would still give you the quick transition, and have some pull as well..

I love my slege with the YS63. Because I can just punch it and it takes off like a rocket. So I know is going to be hard to beat that. But if the Yak would do that with a OS91FX it would be perfect.

As for CG I think 1 1/4" was perfect for me. It was almost neutral upright and inverted. I just needed hair of down elevator to keep it flying level inverted. I think anything past that would put in on the tail heavy side. Meaning climbing while inverted with no inputs.

RE: OMP Yak build
 

I'll be eagerly awaiting the results of all the prop tests because I need to buy some for my Magnum 91, too. I'd test some, but I won't be able to fly mine for a couple more weeks.

The only way I can get mine to balance is to mount the battery in the LE of the left wing, which doesn't seem such a bad idea. I'm thinking of just putting the battery and the switch in the wing and not worry about the fuse hatch. Anyone else done it this way? I figure I have to take it apart anyway, so the plugs will be available to charge it.

RE: OMP Yak build
 

joebob,

For a brief descriptions, I mounted my JR R700Rx in the where it is on the plans.
My 1650mh 6volt NimH battery is just in front of the wing tube on left hand side. Its in between the wing tube and the leading edge in the fuselage. I didn't make a hatch. I just put some layers of clear packing tape over the holes. So far it as worked for 1 day of flight. It hasn't come off yet. I don't think the tape will come off because it didn't get any exhaust goop on the tape at all.

As for my swith. I had a JR heavy duty charge switch laying around. so I used it. I mounted it about an inch above my battery. I just cut out the wood, and the foam. I had to dig out a little foam with a screwdriver to run my battery wires to the switch. I put a little CA on my screws to make sure the screws didn't come out of the balsa.

But I will try and shoot some picture tonight, and post them so you can see how I did it.

RE: OMP Yak build
 

Thanks, m.gramblig. I'd like to see the pics when you get a chance. I was trying to figure out how to mount the hatch cover where the ply doublers are and couldn't come up with anything decent. I was thinking that the weight of the battery in the left wing would help the lateral balance a little by offsetting some of the engine weight.

All that's left on mine is the right fuse side and the rudder, plus smoe stripes on the bottom of the wings and tail. I waited on the stripes til I found out how much covering I was going to have left. Or, I may do the 'Pro Bro' lettering instead. Can't decide.....