4" Jayhawk

[Martin Vrstal]

So here it is for now, and maybe for sometime. I'll keep plugging away and keep you guys posted.

 

[gerbs4me]

its a beauty
you did a great job on the Jayhawk Martin, you gonna fly t at Midwest Power 2?

 

[Martin Vrstal]

Gerbs...
Thank's and yes if it's all finished by then. Guess I have a good month to git-er-done.

 

[Martin Vrstal]

I managed to attach the conduit and also all the fillets to it and also the fins. Today I glassed one side...tonite I'm in the middle of doing the other.

 

[Martin Vrstal]

I've been working steady on this the last couple of days. All glassed and sanded on both sides. I also added 3" by making a 3" payload section to wich I'll screw the NC to. Total length of this Jayhawk will come to 50" and weighs in at 48.13 oz.

Here's some new pics.

 

[Martin Vrstal]

Bottom view.

 

[Martin Vrstal]

Side view.

 

[Stones]

Beautimous Marty!
Can't wait to see her with paint and decals.

 

[Stymye]

looking good , that should be one sweet performer!

 

[gerbs4me]

What motor do you plan on using in it?

 

[Martin Vrstal]

Plans are for an I-211.

 

[Ted Cochran]

Originally posted by Martin Vrstal
Plans are for an I-211.

Terrific project. ( I'm kinda partial to AQM-37s)

Do you think it might be a bit underpowered on an I211? What's it weigh?

Are you planning on electronic deployment?

Cheers,

--tc

 

[Martin Vrstal]

Right now it weighs in at 48.13 oz's. But....I still need to do paint and decals, chute and recovery harness.

I guess if I could find somebody with a newer Roc Sim program who would be willing to sim this thing out...all I have is the demo version. If anybody would be willing...I could e-mail all the detailes to them...any takers?

 

[Martin Vrstal]

Also.....sorry, but no duel deployment.....haven't gotten into electronics as of yet.

 

[Missileman]

You are right in the ballpark of my last 4" scratch project with that weight.
I flew it on an I195 to about 3K.
You should be ok with the I211 but may need a short delay.
Need to sim it. I am working all weekend and don't have access to Rocsim here at work or I would do it for you.
When do you plan to fly it?

 

[Martin Vrstal]

When and where.....MidWestPower 2...I'll probably fly it on Saturday.

Go Here ...

https://tripoliquadcities39.com/page11.html

 

[DumasBro2]

You'll be fine with an I211-S. Have you added any nose weight yet? I think I added 3 pounds to my sons Jayhawk. If it isn't any heavier a medium delay would be in order. Best to run a sim.

-steve

 

[Ted Cochran]

Originally posted by DumasBro2
Have you added any nose weight yet? I think I added 3 pounds to my sons Jayhawk.

Another 4" Jayhawk? Cool!

I was guessing a pound for nose weight, and then motor, harness, chute, finishing--it could get to 7 pounds or so, right? An I211 should work then. I fly 2X Mars Landers on that, and it's been in the bottom of my Quantum Leap a few times, and it will get it up there pretty well.

Now if the dry weight had been 10 pounds, I'd worry more.

Good Luck!

--tc

 

[gerbs4me]

An I211 should be fine Martin, If I had the new version of Rocsim, I'd sim it for you, but I only have the demo as well
cool, your gonna launch it on Sat. thats when I plan on going too

 

[DumasBro2]

OK, I know I've posted pics of this before but I'm not sure which ones. https://rmpitzer.syr.edu/launch/ldrs04/gerber/pages/scan10.html
The c/g is near the front of the "wings" IIRC and is only marginally stable with a J350. No problems with an I211 but an I284 is almost perfect. After all with a rocket like this you want to see the flight.

Best of luck

steve

 

[Martin Vrstal]

DB2...Thanks for the great pics and flight info. I haven't added any nose wt as of yet, guess I wanted to get all the recovery parts added first. All I've been doing is sanding fiberglass lately...how fun.

 

[gerbs4me]

cool pics DB2
either of those motors will make a great flight

 

[Martin Vrstal]

Work Update:

I had our very own Bruce Levison (Teflonrocketry1) run all my weights and measurments in Rocsim. Looks like I'll have to add 3-4 lbs of weight in the Nose in order to bring it to a stable flight. This will bring total flight wt. to around 9 lbs....prob a little more.

Our friend Doug here on the forum, sent me 2 sets of heavy duty rail buttons. Holes are drilled. I added a small dowel rod to the inside of the BT for the upper button screw to screw into.

I made the antenna mounts from balsa, dowel, and weed eater string.

Tonight, I felt brave enough to give the main body section some primer. With not enough grey on hand, I had to go white.

 

[Martin Vrstal]

Here's a pic of the antenna parts installed.

 

[Stones]

Lookin good Marty. I know what you mean when you say" brave enough to....". It never feels like you've prepared quite enough to start throwing on paint. But, in the end, it all comes out. I'm sure you'll have it looking beautimous.

 

[teflonrocketry1]

Originally posted by Martin Vrstal
Work Update:

I had our very own Bruce Levison (Teflonrocketry1) run all my weights and measurments in Rocsim. Looks like I'll have to add 3-4 lbs of weight in the Nose in order to bring it to a stable flight. This will bring total flight wt. to around 9 lbs....prob a little more.

Based on what others are saying for similar models, I think the simulations are pretty close. Marty posted the screen shot from the RockSim 7 file I created using the fins on fins technique I wrote an article about in the Apogee Peak of Flight newsletter. Does anyone know the CP of the real rocket? I did a search and didn't find anything.

Bruce S. Levison, NAR #69055

 

[gerbs4me]

very cool Martin
clever idea using weed eater string

 

[Martin Vrstal]

Photo update...

Here's the latest shot. I've spent the last several days in the prime/sand mode. Yesterday and today I was able to get some orange on this beast. Hope the pic gods like it.

 

[Martin Vrstal]

And the side view...

 

[Stones]

Saaaweeet! She'll really stand out with the decals on it. Looking forward to the end result Marty. Great job!