Johnny Star Commander (Shrox design)

[Bill S]

Just finished up an Johnny Star Commander rocket by Shrox (sold by Apogee). This was a difficult build, made worse by my having great difficulty in getting the balsa as defect free as possible. This resulted in a lot more Bondo putty on the balsa, with multiple coats of primer, etc. The finished rocket is about a half oz heavier than "nominal", which surprised me - I expected much worse.

I didn't want to attempt the masking for the red areas on the wings, etc, so I broke out some automotive pinstriping. I think it turned out fairly well, all things considered.

Because the rocket is overweight and tends to weathercock, Rocksim says that I should use C5-3, D16-4/6 (calm conditions only) or D10-5 motors.

 

[neil_w]

Looks great! I really like that design. Needs a better name, but I can forgive that.

 

[Ulexis]

Well done! Looks beautiful.

 

[GlenP]

I was going to say something snarky, but I just can’t, that thing looks awesome! great build!

 

[Cl(VII)]

That is beautiful. Well done.

 

[Bill S]

Thanks guys. If the scheduled launch happens this weekend, its going to get a flight or two.

 

[prfesser]

That is a beautiful job! Still sanding mine after filling/priming.

 

[Rktman]

Really spectacular results! Big congrats.

 

[Vitruvius]

WOW!!!!!! I had never heard of this Rocket before. I think I'm going to et myself one.

 

[Bill S]

Apogee or Erockets sells it.

 

[Vitruvius]

Thanks, Bill S. I don't live that far from Erockets store.

 

[Bill S]

Finally got to fly the Johnny Star Commander yesterday, on an C5-3. Wind was 5mph-ish, rocket had a little weathercocking but not much. Didn't go as high as I would have liked to see , maybe 300' at best. Safe recovery though, so there's that.

The recommended on the package C6-5 needs 123" of rod to get up to a safe speed, altitude no better than a C5-3 really...

I also Rocksimm'd some other engine choices, such as Quest D16s, but they require a 4' 1/8" rod - the rocket needs 45" to get up to "safe" speed. The club I fly with doesn't have a 4' rod and they didn't seem enthusiastic about my buying a 4' rod and donating it to the club so I could fly the JSC more safely. Otherwise, its down to an older Aerotech D10-5, which I have a few of, but they are hard to find these days.

So I don't know how much this rocket will actually fly at this point. Nice display piece, hard to find good engine choices for (C5-3, D10-5, D24)

 

[Bill S]

Edit... it was suggested to me that I should add a set of 3/16" launch lugs so I could use the longer 3/16" launch rod, but that would be tricky now since the rocket is painted, etc. I would suggest it as an optional add-on to someone who is building one though so you can use the D16s, etc.

 

[neil_w]

I also Rocksimm'd some other engine choices, such as Quest D16s, but they require a 4' 1/8" rod - the rocket needs 45" to get up to "safe" speed.

Try simming with the forthcoming Quest D20s and/or C18s. Motor files are on Thrustcurve.org. It looks to me like (just from the curves) like they have significantly more kick off the rod, although I haven't tried simming anything with them yet.

 

[Bill S]

I did some simulated launches with the D20 in the Johnny Star Commander. Lovely. 661 feet vs 594 for the D16-6. Needs 33" of rod, vs 45 for the D16. .6 second past apogee for parachute ejection, very nice.

I couldn't find any way to download the data for the C18 yet. Figures... I just picked up a bunch of C12 and D16 motors (Bellevue is having a really good retirement sale), but those D20s deserve a try. But they don't seem to be available yet.

 

[Bill S]

An long overdue update. I have flown this rocket twice on Quest D20-6 motors, good flights.

 

[Huxter]

Beautiful rocket! Would love to see any flight pics or vids!

If you were to build this again, would you upsize the engine mount? I too, will probably get one.

 

[Rktman]

An long overdue update. I have flown this rocket twice on Quest D20-6 motors, good flights.

You did an impressive job building her, and now two great flights to match. Congrats!

 

[Bill S]

Beautiful rocket! Would love to see any flight pics or vids!

If you were to build this again, would you upsize the engine mount? I too, will probably get one.

If I were stuck using C5-3 motors, then yes, I'd upgrade to a 24mm mount and add noseweight (it already has a fair bit). Since I discovered the D20-6 works well in this one (about 600'), probably not needed. If I need more oomph, I can put an old D10-5 in it and see how it goes. Given that this is such a beautiful and hard to build rocket, I don't plan to fly it very often, hence flying to "only" 600' is just fine for me.

 

[AfterBurners]

nice work. Pretty flawless!!