Ukey 40/Gotcha Streak Engines

[J.B. Morrison]

Hi All,

I'm new to this forum and trying to get back into the hobby!

I purchased a "Gotcha Streak" kit last fall, and was planning to install a Fox  .35 in it. However, I just aquired an unassembled Ukey 40 that came with an O.S. LA .40. I'm now wondering how the Ukey would do with a Fox .35 and save the OS40 for the "Gotcha". Amy thoughts?

Thanks,

John Morrison

[Peter Hess]

John:

The Ukey 40 will fly just fine with a Fox 35.  I have flown my Ukey 40s with a Fox 35, Thunder Tiger 25, OS 35FP, OS 40FP, and Brodak 40.  With the Fox 35 I suggest you use 61 feet of .015 lines and with the more modern and larger motors 62 feet.  On 62 foot lines my Ukeys seem to like lap times of 5.1 to 5.2 seconds but with a solid motor run they will do quite nicely at 5.4 seconds per lap. 

I would suggest that you move the bellcrank on the Ukey to the bottom of the fuselage.  Otherwise you can have trim problems with a too low vertical CG.  I would also suggest that you substitute  Two wheel landing gear, especially if you are going to fly it from a stooge.

Good luck with the Ukey.  It's simple and ugly, but it is remarkably capable.

[Larry Fulwider]

 . . .
 . . .

 . . . I would suggest that you move the bellcrank on the Ukey to the bottom of the fuselage.  Otherwise you can have trim problems with a too low vertical CG.  I would also suggest that you substitute  Two wheel landing gear, especially if you are going to fly it from a stooge.

Good luck with the Ukey.  It's simple and ugly, but it is remarkably capable.

John --

Some might disagree, but I'm with Peter 100% on moving the bellcrank. I don't see the point in trying to trim an airplane with a built-in handicap of a "too low" CG (I'm assuming the two wheel gear swap, never had a single wheel U-Key)

CG is critical with the small tail -- 1/8" too far back and it's like trying to fly with an egg-beater up your hiney with a wild man turning the crank. 1/8" too far forward and it doesn't turn at all. My preferred CG is 2 3/16" from the LE (Vanessa), with 2 1/4" getting marginal. With a Fox 35 and Fox Muffler, that is about where you will be (at least that was true on the old Joe Just versions).
       I've had three or four U-Keys (depends on how you count a "new" one), and all took additional wing tip weight -- 1/2 to 3/4 oz from my notes. All had an outboard trim tab for final wing leveling.
       Peter's line length / lap times are fine. My previous preference was a foot shorter, maybe a .1 sec faster, but right there is fine.

The Gotcha III probably needs the LA 40 anyway to do it justice -- it is a lot more airplane than  the U-Key!

       Larry Fulwider

[Damian_Sheehy]

CG is critical with the small tail -- 1/8" too far back and it's like trying to fly with an egg-beater up your hiney with a wild man turning the crank. 1/8" too far forward and it doesn't turn at all. My preferred CG is 2 3/16" from the LE (Vanessa), with 2 1/4" getting marginal.  <Snip>

Why not replace the tailplane with a bigger one?
It will improve the stability, allow a wider range of acceptable CG, and would be far more forgiving for a beginner.
I'm also learning to fly C/L and wish I could get my hands on a Ukey .35, but I gather no one is making them any more.

Happy Flying  

Damian

[Larry Fulwider]

Why not replace the tailplane with a bigger one? . . .
It will improve the stability, allow a wider range of acceptable CG, and would be far more forgiving for a beginner.  . . .

True. Only one of mine had the stock tail.

I'm also learning to fly C/L and wish I could get my hands on a Ukey .35, but I gather no one is making them any more.

Happy Flying  

Damian

Damian --

Last I heard, Jim Pearson was still making them. Check the archives here or at SSW to get Jim's e-mail address.
         A couple of weeks ago, Tom Dixon (I think) had one for sale at the Huntersville contest. Ask around, you'll find a U-Key with not too much effort, I suspect.

       Larry Fulwider

[Paul Taylor]

Hey John,
If that is your new Fox, remember you will need to run a gallon of fuel thru it to break it in. If you want to break it in at the field let me know and I will bring my stand. And ear plugs.

[J.B. Morrison]

Paul,

Since I fully expect the U-key to be "planted" a few times, I'd like to use my old (1970's vintage) Fox .35 on it instead of the newer unrun one I got off E-bay. However, no muffler for the older Fox, and the newer one has one.

Interesting ideas about relocating the bellcrank, and I'm going to mount a conventional landing gear to it in lieu of the single wheel.

Have fun at the "Fun Fly" on Saturday!

John

[Paul Taylor]

Hey John,
Get the U-key snapped together and we will go out and fly it on a lunch hour.

[Brett Buck]

Since I fully expect the U-key to be "planted" a few times, I'd like to use my old (1970's vintage) Fox .35 on it instead of the newer unrun one I got off E-bay. However, no muffler for the older Fox, and the newer one has one.

   If you run it on a profile, please do yourself a favor and install the burp fix. Saves on needle valves, if nothing else.

     Brett

[J.B. Morrison]

Showing my ignorance here, but what's a "burp fix" (check valve?)?

Also, what props to start with on the Ukie 40, usnf a Fox.35 and .015x 60' lines?

Thanks in advance!

John M.

[john e. holliday]

Supposedly the old reliable Fox .35 Stunt will cough during a maneuver.  I myself have never worried about it.  What it is a pece of hardwood inserted in the bypass port.  You may find posts on possible fixes by using the search engine on this forum.  If you have the props, the APC 10-5 or 6 will work.  Just don't lean it out to far.  I also use Top Flite 10-6 or 5.  Even have some Master Airscrew 10-6.  Let us know how it goes.

[steven yampolsky]

Hi All,

I'm new to this forum and trying to get back into the hobby!

I purchased a "Gotcha Streak" kit last fall, and was planning to install a Fox  .35 in it. However, I just aquired an unassembled Ukey 40 that came with an O.S. LA .40. I'm now wondering how the Ukey would do with a Fox .35 and save the OS40 for the "Gotcha". Amy thoughts?

Thanks,

John Morrison

Ukey 40 needs something heavier in the nose than Fox 35. I spoke to the designer and he said that it was designed for 40FP.

[Paul Taylor]

Showing my ignorance here, but what's a "burp fix" (check valve?)?



Thanks in advance!

John M.

John,
See photo or call me if you have questions. I had one that burped so bad it almost sounded like it stopped and restarted in flight. Would scare the crap out of me. Did this fix by Dennis V. and it never burped again. From what I understand it only effects profile planes.

[Garf]

My McFox conversion seems to cure the burp also. More power too.

[Paul Taylor]

Phil,
Can you share a little more details on that please?

[J.B. Morrison]

What's the theory behind the "burp fix"? Increase back pressure in the cylinder? Would phenolic work  or would that melt?

Paul, looks like it might be nice and steamy weekend to fly!

John M.

[Mark Scarborough]

Ukey 40 needs something heavier in the nose than Fox 35. I spoke to the designer and he said that it was designed for 40FP.

The designer gave my Ukey to me a few years back, I flew mine, ( its the big one) with an LA .25. Never had any complaints about performance even when it was 95 degrees. I have now flown probably 4 or 5 aboslute newbies on the plane and thats why I keep it in the fleet.

[Joe Just]

There were two designers of the original ukey series, Jim Carpenter and myself.  We realized way into the first 500 or so that the names should not have been Ukey .35, Ukey .40 but should have been Ukey 400 and Ukey 500 to reflect wing areas. the ukey .15 should have been named the Ukey 300. Either the .35 or the .40 can be flown quite well with a LA .25, just balance on the spars about half way out from the body.  I sometimes wish we never had to give up the Ukey projects, but that's water under the bridge now.
Joe

[Brett Buck]

What's the theory behind the "burp fix"? Increase back pressure in the cylinder? Would phenolic work  or would that melt?

   It takes up space in the bypass, increasing the gas velocity, so that the charge goes up the bypass at a good velocity. And is thus less affected by accelerations. It is a definitive fix for the issue, the *only* definitive fix for the issue.

    Brett

[steven yampolsky]

I sometimes wish we never had to give up the Ukey projects, but that's water under the bridge now.
Joe

Joe, the Ukey was a wonderful airplane. I learned to fly inverted with my Ukey. A testament to how sturdy the model was: I bought a dozen of wood props and broke all but one while trying to learn to fly inverted. The model survived it all! I still have Jim's Ukey 2000 prototype that I fly occasionally. What a fun design!

Thank you J&J!