TT2

My Feedback: (13)

I'm going to be scratch-building a new profile soon (just feel the need to do some design / build work to reduce my balsa stockpile). I want something like the OMP Yak but a little smaller so I can use a Saito .91 for power...and have plenty of power to spare. I don't think the Saito .91 will pull the OMP Yak around with the authority that I want, and I don't feel like buying a larger, thirstier four-stroke.

Anyhoo...the only thing I don't like about any of my other profiles is the fact that the wings aren't removable!. It makes transportation a bit of a problem when there's a large number of planes of varying sizes going in the same load. For this reason I'm really interested in the Yak's wing mounting system. From what I gather from the pictures I've seen and the tons of assumptions I've made, I think I know how it works. I'd appreciate that 'those in the know' take a look at my assumptions and correct me where I'm wrong:

1. The wing spars extend into the opposite wing halves to act as a 'floating spar' like on the Composite ARF (Fiberclassics) planes.
2. The root ribs are plywood and have tabs that extend past the LE and TE. These have holes in them and can be bolted through one wing, then through the fuselage, then through the other wing.
3. The massive thickness of the wing provides enough surface area to the fuselage sides that when the bolts are tightened, the wing won't rock.

Am I very far off base here? I'd love to see some pics of the wing mounting areas of someone's OMP Yak to get a better idea about how they did it...or a detailed explanation would be great!

Thanks in advance,
-Tom

capthis

My Feedback: (67)

The omp yak has an aluminum tube that slides through the fuse and into the wings, like a "big" plane has. You know with the outer tubes in the wing.

#2 you are right, and prolly so on # 3 as well.

TT2

My Feedback: (13)

Wing tube eh? OK...that might make things a bit easier. I might try to use some CF blade-type spars to save weight if I can come up with a suitable design. Months ago I came up with a design for a larger, completely sheeted-foam profile and posted them here. That plane was designed around a TT 1.20 two-stroke engine. I envisioned using sheeted foam surfaces for EVERYTHING so that the plane could be built very quickly. Naturally there were tons of lightening holes...

-Tom

matlok

Sounds like a very interesting design - I've been looking at the OMP Yak also for a Saito .91 I already have, but had the same power concerns you have. I kinda tooled around with the idea of scratching something out for it, but I got busy with the Katana project so I dropped it. The wing tube/root tab/bolt method sounds like it would work well. I personally would rather see a foam fuse w/built up wing and empennage than just an all foam plane. With the availability of laser or router cutting nowadays you can design it so most if not all of the wood parts are pre-cut and fit, and all the tedious cutting/fitting/sanding is virtually eliminated. That's how Paul's FF Taco and Burrito are, as well as MatchlessAero's new Pitts and my *soon to be* Katana.

Hope things come out well - you've got me wanting one already!!! If you need any help I'd be glad to do whatever I can.

TT2

My Feedback: (13)

Matlok, this plane will be a different beast entirely...totally built up. Maybe a foam core fuselage, but haven't decided yet. I'm thinking 60" span with a planform proportionately similar to the Yak. I thought about doing an Edge 540T but I wanted a little sweep-back on the wing LEs for better flat spins and snaps. I've got a source for laser cutting and might have the ribs cut out for the first one after I get the plans done. Nearly everything else would just be sticks and sheet. Shouldn't be very difficult to design or build.

I really like your Katana Profile! I'm a huge fan of Katanas...I have a H9 Funtana, two GSP 72" Katanas, and have been kicking the idea around about getting the Exclusive Modelbau Funtana or 35% Katana (but geeeeeez those kits are expensive...maybe they should change their name to Expensiv Modelbau).

-Tom

tpstorey

Just my 2 cents: I think most designers have given up on the blade type plug in wing in favor of the tube. The blade tends to focus all the pressure to the edge of the blade and falure there is common. The tube distributes the weight better.

m.gramling

My Feedback: (8)

I have heard the OMP yak comes in at 7lbs.

All you have to do is build your OMP YAK light. lightweight battery packs. Micro servo on throttle. Heck you could even cut the wing span down a few inches. Cut holes in the foam fuselage. If you could get the plane down to 6.5lbs. I think the Saito91 would hover it fine.

I had a Saito91 on my UCD and its weight was 7.5lbs. Pull out was slow but it would pull out. So if you keep the weight down to 7lbs or below, pullout would have to be better.

I am got one of they YAK's ordered. Will start building on it after Christmas, will put on a OS91FX.

TT2

My Feedback: (13)

Good points, but if I design / build then I can use up some of the contest balsa I have. Plus, the price of the OMP kit is rather high for a profile kit. Heck...I paid another $50 for a GSP Katana that is one helluva plane after some modifications...and it was covered when I got it!

I'm really shooting for 5.5-6.0 lbs. RTF dry weight, and I think that's pretty easily attainable with a 60" WS.

The fuselage will most likely be framed interior 1/2" x 1/4" medium balsa with 1/8" contest balsa sheeting. Probably some 1/8" lite ply around the wing tube / wing bolt area for rigidity, and some 1/8" lite ply (replacing the balsa) from the landing gear forward. Sound good?

The wing will have 1/8" lite ply root ribs, 1/8" contest balsa ribs, 3/8" x 1/4" medium balsa spar caps and 3/32" medium balsa shear webbing. 3/8" x 1/4" medium balsa TE probably. 1/16" x 3/8" cap strips, 1/16" contest balsa LE, TE and root section sheeting.

Do you think that 3/8" x 1/4" medium balsa sticks would be overkill for the tail surfaces and ailerons, or would 1/4" x 1/4" medium balsa be a better solution? I've obviously got a bunch of 3/8" x 1/4" medium balsa sticks in the woodpile. What does the OMP Yak Profile use???

I'd like to use twin HS225s for the elevator halves and a standard-sized servo for the rudder and each aileron. Micro Rx and 6V 720mah NiMh pack.

Any input would be greatly appreciated! I'd like to get started on this thing very soon.

-Tom

PaulSwany

My Feedback: (45)

3/8" x 1/4" for the tail feathers sound like a good choice to me... Make sure to do the center section of the horiz stab with grain perpendicular to the fuse.

m.gramling

My Feedback: (8)

At one time, I heard people was making the Morris knife into a .60 size.

If I am not mistaken they were added extra rib to the standard wing on each side. And I think they made the fuselage 4" longer. they were running OS.61on theirs.

I think they were up north in IN, or OH.

Maybe somebody here can chime in to help.

AFSalmon

My Feedback: (3)

Tom,

Correct assumptions of the attachment sequence. We use hardwood dowels in the fuse for the wing through bolts and of course the aluminum spar. The very first prototype Yak 54 was 6 1/4 lbs but used a wood spline made of 1/4 balsa with 1/16 ply siding (sort of like an I-beam). Was plenty strong enough and lighter than the aluminum tube but harder for the builder to get right. The a-tube is very easy to build and readily available. I agree with above in that the YAK 54 could be built with CF tube, lightening holes in the foam core and contest balsa and come in around 6 lbs. Just food for thought!

Mike Pilkenton
OMP

akahoverit

My Feedback: (2)

AFSalmon, how are the ARF's coming along?

AFSalmon

My Feedback: (3)

We are working with the company now and the 80" Edge is being arfed as we speak. We expect the first shipment in Jan. The others are being prototyped as ARFs and we have to evaluate first. Seems to be a rapid turnaround though so I'm still very optimistic about having all the profiles available by next spring. We'll be taking limited orders for the first run of 80" Edges soon on the website so stay tuned at "www.ohiomodelplanes.com" in the next couple of weeks.

Mike