SD Models 40% YAK

[MikeC3D]

If you have this plane or have flown this plane, please give me some feed back on it. I know it is heavy in STOCK trim, but that can be overcome fairly easily. How is the construction of the airframe, strong , flimsy etc. I seen one fly this weekend with a 3W157, and half a hobby shop in the fuse, it weighed 48 lbs , and couldnt pull out of a hover very easily. With a diet and a DA-150 on pipes, or possibly the 170...somewhere in the 40-41 lb range , seems like it would be an awesome bird.

[Flyinrazrback]

2 local flyers built them. Both kept simple, no extra stuff with 3w 157s on cans. Both at 48lbs. Cans would save you 1.5 lbs or so, CF main gear and tube about another pound. 40-41 is going to be a tough goal to reach with this one. I would consider a Kroma 180 or 3w 170.

[AHP]

They're not 'heavy', they're HUGE. They will dwarf just about any other out there. A buddy of mine has one with a ZDZ 210 and it's the perfect combo, IMO. It has foamy-like power and still flys very light. I've seen one with a DA 150 on pipes and care taken to keep it light and it was worthless.. It barely pulled out of a hover and had absolutely no grunt at all. Even if you get it down into the low 40's - which is a tall order - it's still a huge draggy airframe. You don't need to worry about keeping it light with a 200cc + engine.

[MikeC3D]

Well, for starters , I will never fly anything but Desert Aircraft engines, AND lighter planes fly much better. I'm sure Bob can show me how to get down to 40-41 lbs. That is the plan anyways...we shall see...thats if I can find one, so far the 2 dealers I got ahold of were out of stock. Less servos ... push-pull in the tail...smaller batteries...aluminum screws...titanium... CF tubes and gear...lots of possibilities.

[Flyinrazrback]

Well, since you will only fly DA, why dont you consider the smaller 37.5% yak instead, the DA will pull it.

[MikeC3D]

Wing area.....plus I have my fingers crossed for the 170. I plan on making it lighter, so imagine how light on the wings it would /could be.....

[Flyinrazrback]

I think the only way you will be able to lighten up the frame is to strip down the covering and go to work. It is not so much the weight, but the sheer size of the frame and the total drag on the plane due to the size. I think if you are dead set on a DA 150, a smaller diameter high rev prop for most power like a mejzlik 30x10 is in order. Full KS 1090s tuned pipes will help but you will gain 2lbs. Word on the street is there is not even a DA 170 prototype yet, and bet we will not see them in average folks hands until next year sometime. I understand why you want to run DA, but for this application I do not think it is a very good choice due to the size.

[AHP]

I'd have to agree with flyinrazrback on all accounts. You'll never get it down into 40-41lb. The're already built light so I don't see many areas to remove weight with the exception of the gear and wingtube. As for only flying DA, I fail to see the reasoning in letting brand loyalty seriously limit your options... Rather unfortunate, IMO. Regardles, I've put a lot of time on one with a ZDZ 210 and it is a kick ass as combo. Even in the upper 40lb range, it still flies 'ligher' than any other 40% I've owned for flown. I agree, lighter flies better, but ou have an unattainable goal with the wrong engine. This plane is worthless with a DA 150 (or any 150) and will not even balance with one without adding weight. Adding cans or pipes will only make it worse. And again, it's not just the weight, it's the size and drag of the airframe. You'd go through a ton of work just to have a poor to mediocre experience. Use a suitable engine and you'll be rewarded with one of the best 3D planes on the planet.

Here's one that's 52lb's with a DA150 and cans:

http://www.rcuniverse.com/magazine/a...article_id=775

If you're only going to consider a DA150, consider the 37.5%

[MikeC3D]

Yeah well....lots of people said my buddy Bob couldnt get the carden down to 28lbs witha DA100 either, and then said it would break....well he proved that theory wrong, ( 40% Carden 260 on a diet ). The plan is to strip it, lighten it, as for as size and being draggy, again they said the same about the 260, and again Wrong. It advertises as 44lbs rtf, you know thats always a lil off, but 52lbs is plain rediculous. If I have to rebuild parts of it then so be it, we will get i tdown there. As soon as I get my paws on one I'll start taking pics......
If someone had a 40% kit then thats the way I would go, I already have a 35% yak.

[Stainless Skills]

Well if you wanted to modify the airfrom that much then you could probably get it to work.

What hurts is that the airplane is sooo big that even if it was light, it would still create tons of drag.

[AHP]

I happened to follow Bob's build and was a silent supporter. There is a big difference between swiss cheesing what's supposed to be a a fully sheeted and cored Carden than starting out with an already laser cut and stringered SD Yak. Because of the construction of the Carden, there are places where significant weight can be removed, as illustrated by Bob. Have you seen the construction of the Yak? That's not much left to take out unless you plan on removing every other stringer and every other wing rib.. Having been around and flying one I'm not just talking out of my ass. As for drag, it's a Yak; a big draggy airframe! The cowl is a big open parachute. Even if you got below 40lbs, performance is still going to be rather lame if it's being drug around by a 150. And, unless you can make significant weight savings in the tail, you'll need pounds of ballast to get it to balance correctly with a 150. You could always stand the engine off about a foot.. It just sounds like a big waste of time unless you're going to appropriately power it.

FWIW, Aerotech sells a 40% Yak kit.

[MikeC3D]

I remember seeing it, only 2700+ sq.in of area, probably due to the shorter WS. I have friends that have had ZDZ engines in the past and they were troublesome, ( for whatever reason ) Rarely do you see problems with DA's engines, plus their CUSTOMER SERVICE IS EQUAL TO NONE. If DA would produce the 170 or the 200 then thats what I would probably put on it and just leave it at that, but.... When I get one , we will look at it really hard to see if its worth it. I believe it can be done.

[AHP]

I've owned 2 DA's, 3 ZDZ's, 1 BME and 3 3W's and the only one I ever had problem with was the DA. Go figure.. No doubt DA makes a good product with best in class service, but they have a very limited product line. It just seems very counterproductive to me to try and reinvent the wheel when all you need is another engine. Anyone of the big names produce a great product with great service. There are always lemons, regardless of brand. Variety is the spice of life!

Anyway, please do a build thread if you pursue it. I'm interested to see what can really be done. I've considered one for myself a few times, but I have a hard enough time transporting my 'regular' size 40%'s..

[Flyinrazrback]

Consider the kroma 180, you speak of customer service as a top priority, theirs is AS GOOD as DA.

[adrian]

bump a 3w 170 on factory cans into it - thats it and it will be a show stopper!!! really!!!

PS the 40% sd yak is light for its size!!!