I've just about finished up an Estes Pro Series Jayhawk (No pics yet, still needs decals). It was built mostly stock, with a longer engine hook, longer shock cord, thin epoxy fillets, papered winglets, and (quite) a few layers of paint. Listed weight is 8.6 oz, mine weighs in at 12.5 oz.

The included nose weight was 0.9 oz of clay; I used 1.5oz of BBs & Epoxy. Guess paint weighs a lot!

So, I'm trying to figure out if more nose weight is needed to keep this bird stable, given its final weight. The plans don't list any CP or CG. It currently balances about 17" from the NC tip, w/o motor. The full length is 30.5". I'll initially fly it on an E18 RMS, though would like to keep it light enough for the E12.

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Paul
If we weren't all crazy, we would go insane - Jimmy Buffett
NAR #87246 www.wooshrocketry.org

Hi Paul,

I don't have an exact answer for you; but I do have some info that may help.

Madcow makes a similar model. At roughly the same diameter, having a length within .75" of one-another, and both including boat tails, I am fairly certain that their CP's are fairly close to one-another. Madcow lists their safe CG as 19" from nose tip. I'd say that if the Pro Series Jayhawk balances 19" or less from the nose tip when fully loaded, you *should* be stable.

Good luck this weekend!

-Eric-

Paul, is the Estes Pro Series Jayhawk a re-release (or an updated release) of the old Centuri Magnum D Jayhawk? Just curious...

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Dean Fox
NAR #53946SR

---- "Wherever you go, there you are"

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Layne Pemberton NAR# 83083
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They are two completely different kits. The Estes Pro Series Jayhawk used the 2.5" tubing used on the Pro Series Impulse and Pro Series Maxi Force. The Pro Series Jayhawk had a custom nose cone that has some extra details that are not on the PNC-80K used in Centuri's Magnuim-D Jayhawk.

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'Til next time,

Mike Toelle

NAR 31692 L1

SAM 0373

Well, the weather didn't cooperate at our last launch, so I'll try it again tomorrow. Our club Jayhawk expert tells me to get the CG at or above 60%, about 18" from the nose. It wasn't quite there with an E18, so I've added a bit more nose weight, and am now at 17", a comfortable 56%. The CG should be Ok with an E12 too, though not sure about rod speed...

Here's a pic of the completed bird. The only thing missing is 2 of the white star & bar decals; despite 2 coats of decal film, they still fell apart. The rest of the decals went on fine.

The scale details of this kit really make it. My color is probably a bit off scale, I simply used an old can of F&F orange lacquer.

Attached Thumbnails

 

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Paul
If we weren't all crazy, we would go insane - Jimmy Buffett
NAR #87246 www.wooshrocketry.org

I built this bird pretty much stock, using FnF for the fins and BT, and Valspar rattle can paint. The only significant change was rigging the engine mount to take the E9 motors.

It has flown on D12-3s and E9-4s and has never had an issue with rod end velocity or apogee altitude.

Here it is in a drag race with a Satellite Interceptor upscale and a FSI Black Brant II clone on a D12-5:



FC

That is awesome! Nice shot!

I bet I know who DIDN'T win the drag race...

Looks great! I have not summoned the courage to fly mine.

Allen

Hey Paul...Looks Great. Some day I'll get around to building my pro series Jayhawk.

Dittos ...

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Lee Reep
NAR 55948

Projects: Semroc Saturn 1B, Ken Foss Designs Mini Satellite Interceptor
In the Paint Shop: Nothing! Too cold!
Launch-Ready: Farside-X, Maxi Honest John, Super Scamp