This is my first new design this year (IIRC), and might even be my first in over six months! I've been 'recharging my batteries', and it's been a slow trickle charge fer sure...

First item: RockSim is throwing up a NAN on this design, for reasons I can't locate. It may be my installation of RS acting funny, so if someone could run a few sims with the file, I'd like to hear.

Second item: This is not true-scale, in that the lines of the Dragon QTV are totally wrong, and the lengths of the tubes are wrong. However, the length of the model is 1/70th the stated length of 178' for the prototype, and the diameter of 2.04" (ST-20) is only 0.01" smaller than the prototype diameter of 12'. If I can locate the correct shape of the QTV spacecraft and other dimensions, I'll correct this design. In any event, this should be an impressive bird in flight.

Specs:

Length: 30.51"
Diameter: 2.04" (ST-20)
Weight: 3.71 oz
Fin Span: 4.04"

Use a 3/16" launch rod. Since the simulations were NAN, I don't know about guide lengths or deployment velocities yet.

See what you can get it to do!

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Attached Files

Falcon 9 QTV.rkt (64.4 KB, 80 views)

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Craig McGraw

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AMA 352635

Here ya go.

From the revised file:


v.2 minor tweaks by Jay Goemmer
1) Changed "static margin reference" to Maximum Frontal Diameter.
2) Added 2 SE-14 screw eyes at base of nose cone.
3) Moved parachute 1.5" forward.

Stability margin is still only 1.31 calibers on a 24mm "C" motor.


First two sims are with "Max Diameter," the second two with 1 more SE-14 in the nose cone, and the last two with two SE-14's.


That's about all I can do just now. (shrug)


Cheers,

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Falcon_9_QTV_v2.rkt (118.1 KB, 71 views)

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Jay Goemmer
"Centuri Guy"/"Tau Zero"
YORF Member 28
Semroc SAM #0029
NAR 86131


"I think about organizing things all the time. Never seems to happen. I find something that piques my interest and I'm off on a quest. Or a Centuri. "

--Bill Eichelberger, 02/22/2022


“Centuri fret buzz in an updated form.”
Bill “Wallyum” Eichelberger re: Estes Flutter-By
03 Sept 2014

Thanks, Jay!

It was Max Frontal's problem... He went Full Monty...

The length of the rocket was wrong, but I located another reference from Spaceflight Now with a length of 154' for the QTV flight. This drops the length down to 26.4". I was able to get a simulation after changing the margin reference point, and loaded up a D12-5. Next, I tweaked the fin shape and size until I got a margin of 1.39.

Did I say this would be impressive in flight? See the specs below...

Length: 26.4"
Diameter: 2.04" (ST-20)
Weight: 3.65 oz
Fin Span: 5.54"


D12-5......912'......Dv 18 FPS......33" guide length (use a 48" x 3/16" rod)


Now try it out! Enjoy!

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Attached Files

Falcon 9 QTV Mk III.rkt (72.3 KB, 78 views)

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Craig McGraw

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SAM 0044
AMA 352635

Sideline thought...

I wonder how close the Dragon QTV capsule comes to the SEMROC Orion nose cone? These two designs - minus the Orion's pods - are mighty close in size...

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Craig McGraw

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SAM 0044
AMA 352635

I just ran some additional sims using the E9-6, and the performance was astounding.

Altitude 1469', with 6 out of 8 sims giving a Dv of 5 FPS (all sims less than 12 FPS!), on a guide length of 43".

Margin is 1.04, so it's still technically stable for flight. This will improve as the engine burns off some mass...

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Craig McGraw

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SAM 0044
AMA 352635

Craig, this looks GREAT! I want to build it!