What with the first Kwikkee Stunt contest only a couple of weeks away, and having trashed my Skyray and Bullet models, I am busily building a new one.  This is a Kwikee version of the Skyfire.  It has 220 sq.in. wing and will be AP Wasp powered.  So far, I have maybe 3 hours work in it.  Probably 2 more and ready for finish.  These really go together fast.

Structure all assembled (the photo had pins etc to hold it together).  First epoxy on the nose and in the engine mounting holes is setting up as I write.  I figure one coat of dope, light sanding and two of clear, gloss Urethane will do the trick, and it will be ready to fly this weekend.

"This is a Kwikee version of the Skyfire. "

Hmmm...Are the wing swept forward??

Look'n good!

"Tight Lines!"

Wes

Progress!  2 coats of clear dope, sanded with 600 grit.   Added the decals and stickers.  Ready tomorrow for a coat of Lusterkote clear.  Then add the hardware, and go fly it!  I have an old 2/3oz. Perfect tank I modified for uniflo.  I plan to modify a standard Cox spinner hub to the 4mm x .7 thread and use a regular Cox spinner.  Prop will probably be a 5x3 Cox black, as I suspect this puppy needs to fly fast to maintain lift.  A trade-off between speed and structural integrity!

I like it.   Hope it flies better than it looks so we can ask for plans.

!!!!!!  Now Doc,  that's certainly not the ugliest plane in the world...not even the ugliest plane Larry ever designed..

Personally, I like the look.  Maybe a little heavy with all that ply?  But surely tough. I'd like a wheel or 2 on it though.  Waiting for flight reports.

"All that ply" is actually only 1/32" thick.  It is laminated over 3/32" balsa side panels.  The engine bearers are 7/16 x 1/4, drilled out for most of their length.  See the attached photo of the basic parts.  Eric Rule has the cut file....  He does need to re-orient the vertical tail grain, though.  As you can see, the bellcrank and control-horn are provided.

The published, swept forward Skyfire was nearly 11 ounces, this one is nearly 3 ounces lighter, about the same weight as my Sky Sport, which has 40 sq.in. smaller wings.  With the power of the AP Wasp, you really only need something to aim the thrust vector anyway.

It has a single wheel, but that lower fin acts as a tailskid, and there are now two tip support skid wires.  It will sit on the asphalt for takeoff just fine.

Tomorrow, it gets the tank and engine, prop and spinner and it is DONE!!!

Looks great!  If it were me I would have used a 2-56 threaded clevis. Easy to adjust and can't vibrate loose.

I have had VERY bad experiences with clevises on 1/2A models.  The high rpm can cause them to shatter!  Three times on one plane, finally resulting in its demise( one nylon, two different brands of steel).  No way Jose!  Ball joints, especilly the bolt-through ones are certainly reliable.  The nice thing about the setup I chose, is the ease of adjustment, and not needing the rod to be threaded.  If I wanted heavier rod, I could easily drill the pass-through hole larger.  Plenty of meat there, probably to go to 1/8" (though the pin going through the control horn is a bit suspect if the model were larger)

Perhaps when the rod is adjusted to it's final position, a flat would be good.  The screw, unfortunately is metric, so finding an Allan type one may be a problem.

First flight will be this morning!

If you are happy with the adjustment put a drop pf CA on the rod/coupler/screw.  Or do nothing it ain't going to work loose anyway.  Just check it after the first flight or so.

 

I never heard of a full scale aircraft using that name.  Interesting, I'll google it!

First flight was a partial success.  The plane is smooth and shows great potential for maneuverability.  However!!!  The wing flex is downright scary!  Some carbon fiber strip is going to go on, top and bottom.

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First flight was a partial success.  The plane is smooth and shows great potential for maneuverability.  However!!!  The wing flex is downright scary!  Some carbon fiber strip is going to go on, top and bottom.
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A broad wing chord is just about a necessity with 1/8" sheet wings. 

Gee, Ray, how do you make the props sweep back like that?   

Ya just can't get them in a store like that!   

George

Gee, Ray, how do you make the props sweep back like that?   

Say, it ain't easy...send me your props and I'll see what I can do.  (Helps with the speed, you know, streamlined and all that...)

Three remaining problems, now fixed (I hope).  The wingtips occasionally showed some flutter.  I added small (.11 oz fishing sinkers) weights on carbon fiber booms ahead of the tip pods by about an inch to kill the flutter. .

You did what?  Weights on booms ahead of the tips?  To kill "flutter"?  I don't get it. I never saw the problem, much less the solution.  Guess I have a lot more to learn about this stuff than I thought...

The flutter is completely gone due to the booms.  Flutter happens when a wing is flexible in both torsion and spanwise flexing, as mine is.  Moving weight ahead of the "node line" (whatever the heck that is) fixes the problem.  Many full scale aircraft have flutter balance weights on booms ahead of the ailerons and elevator.

The more permanent fix is to move the spar forward and add a stiffener across the mid span.  So sayeth our local aeroelasticity guru Joel Chesler.  I'll keep playing with it, as the booms and weights are not appropriate for a kit or published design.

Anyway, the plane flies as well as any 1/2A I have tried, and took first at the Kwikee Stunt contest yesterday.  John Wright came in second with a Netzband Accentor (I think that is the name).

I think the trim on this model is pretty much "there".  I took it to Clovis and I put up one flight, removed some tipweight and Heman Lee flew a 2nd flight.  It looks just right.  It drew a lot of favorable comments on its performance.   

Now we need more of you out theretryhing to do me one better!  I intend to work up a plan for Blackhawk's magazine.  The fiddely bits are all available laser cut from RSM.

The plan (just completed this morning) will be in Blackhawk's magazine.  The laser cut fuselage and tail parts are available from rsmdistribution.com .  The wing is so simple, you buy your own wood and build it from scratch.