Polecat Jayhawk Kits

Howdy,

Has anyone built a Polecat Jayhawk lately? Did you follow their instructions? Specifically, I'm wondering about the not using fillets part. My son always wants to launch my Estes version, but it has had too many rough flights to fly any more. So I'm looking for a replacement. I'm thinking of getting the 5.5" version. Go big or go home, right? Or is it twice as big is twice the fun?
Any thoughts?

I have the 4" and built it close to spec. That is no heavy duty reinforcements on the wings. It is subject to rough landings and if you overbuild those joints it will snap the fins. The way Andy wrote the instructions, you just have to slide the fin back in (or reattach the winglet) and do a bit of sanding.

Gregzo laughs at me when I tell him this, though it does work, and I've not had to gouge out a snapped fin root yet.

BTW, the 4" is a beautiful flight on an AT I305FJ

Personally I don't buy that methodology, Just tack it with the assumption it will break each flight? Build it with! a fillet, Use a bigger chute and fly it again that day not take it home to fix.............again!



H_Rocket and I always debate this :bangpan:

Mr. SMR is the local jayhawk expert, and I believe he has built all of the Polecat kits. He would be the one to contact for info. You can see some of his stuff here:
https://www.rocketryforum.com/showthread.php?t=15501
The whole family is shown in post 8.

As usual Gary is wrong....:bangbang:c:


I only do this on two kits

1. The Jayhawk
2. The Skeeter

Both have fins prone to break.

Both are single deploy (motor eject) -> bigger parachute =longer walk. -

I'm considering the 5.5" version. Ifd I do, I will try a complete glass layup over the assembled kit.

The Kit in question was the 5.5" ya bone head, Plus I'd rather walk a few more feet than have to fix it every time I flew it. Not to mention making the joints weaker and weaker each time.

jd2cylman said:

Has anyone built a Polecat Jayhawk lately? Did you follow their instructions? Specifically, I'm wondering about the not using fillets part...

Any thoughts?

Click to expand...

I have built both the 4" and the 5.5" Polecat kits, as well as a really big one from Polecat 10" tubing, rings, and nose cone. I put fillets on all of them. The fillets would indeed make it harder to replace a wing, but if I broke a wing I would tear it down and rebuild it from the motor mount anyway, so that wouldn't matter. Anyhow, here is my one recommendation... absolutely put fillets on the winglet-to-wing joint. The most likely break will be the winglet, which always hits first. I have flown the two small ones a bunch times, even landing on the gravel runway at Bong, and have never broken any wood. The winglet-to-wing joint takes the stress, and those fillets spread the stress over a larger area. Without them, I believe the winglet will crack along the pre-cut mortar and tenant joint up the middle. I have cracked the fillets on a few occasions, which is almost desirable, as it is an easy repair. But it does show there is a good deal of energy absorbed at the joint on landing.

Good luck with your Jayhawk. Polecat makes really good kits and the 5.5" flies very nicely on a J415-W.

I have problems with a rocket kit that's designed to break on landing. With a properly sized parachute, this shouldn't be happening.

Saying it's a factor of the size of the fins won't fly -- the Gates Brothers have one that weighs hundreds of pounds, and I don't recall hearing of fins breaking on landing on theirs.

Oh, and Al? Ever heard of this thing called Dual Deploy? :horse:

-Kevin

Oh yeah, take recovery advice from the crater king....


This one is a fun flyer I just stuff a motor in it anf fly.

(yes then I fix it)


The payload bay is reeeeeaaaaaly smalll.

H_Rocket said:

The payload bay is reeeeeaaaaaly small.

Click to expand...

Yes it is!!! I usually fly her with two parachutes and they end up inside the nosecone. The good news, for motor deployment anyway, is that a forward-closure-full of BP is more than sufficient to get everything out.

troj said:

I have problems with a rocket kit that's designed to break on landing. With a properly sized parachute, this shouldn't be happening.

Click to expand...

Not so much designed to fail as designed to be repairable. Andy gave the builder the option on fillets, just saying they weren't required. And you are correct - with a properly sized cute, it doesn't.

My :2:

Hey, Adrian... I see you live in Malta. Not far from me (Rockford). I'll look for your 5.5" at launches - I fly out of Bong (with WOOSH) and at MWP. Are you in QCRS?

Cheers, Sather

SMR said:

Yes it is!!! I usually fly her with two parachutes and they end up inside the nosecone. The good news, for motor deployment anyway, is that a forward-closure-full of BP is more than sufficient to get everything out.

Click to expand...

Never considered two parachutes...

SMR said:

Yes it is!!!Not so much designed to fail as designed to be repairable. Andy gave the builder the option on fillets, just saying they weren't required. And you are correct - with a properly sized cute, it doesn't.

My :2:

Click to expand...

I've broken the fin mount 2 of the seven times it flew. On one, I broke off the winglet. All these repairs tool less than :30 to complete. For my toy, I just don't want to have to gut it to replace a fin. Of course YMMV.

H_Rocket said:

Never considered two parachutes...

Click to expand...

It wasn't an original thought... I was just copying GBR. I thought their full-size looked great coming down under two 26 footers.

H_Rocket said:

I just don't want to have to gut it to replace a fin.

Click to expand...

IMHO the 5.5" fins are more likely to break than the 4", as the rocket is heavier and the lever arm at ground contact is longer. (The fins aren't any thicker, either.) What do you use for recovery? I use twin 60" (or a single 72") on the 4". Twin 84" (always) on the 5.5".

I've been using a 54" PML. IIRC the times it broke It was a bit windy and I dropped back to a 48". Dropped kinda fast and I, accordingly, paid for it.

Wow!
Thanks for all the replies! I haven't got the kit yet. It's on my shopping list when work goes back to 40hrs/week. We're back on 32's again .

Sather, I haven't joined QCRS yet. Other than the "membership" for last fall at Midwest Power 8. I had a bad launch there. Launched 3 rockets. Crashed and destroyed 2 and lost the 3rd. Of course the lost one had my altimeter. We talked a little at the launch I believe. I hope ECOF at Bong will go better.