AKA "Feynman Probe"...

I've had this idea of a forward-pod type of design for some time, and have presented many variations here in the past. This one has moderate to high Dv numbers, but still within the safe region for the average run. It took some tweaking and trimming to get it to this point, but I think it's ready to reveal...

Length: 28.00"
Diameter: 1.04" (ST-10)
Fin Span: 4.54"
Weight: 1.68 oz


B6-4......394'......Dv 9 FPS
C6-5......840'......Dv 21 FPS


All engines reach flight V on a standard 36" x a/8" rod.

Enjoy!

Attached Thumbnails

   

Attached Files

SRV Feynman.rkt (213.8 KB, 95 views)

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Craig McGraw

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SAM 0044
AMA 352635

Is this rear ejection? It looks great but very fragile.

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Dale Marshall, San Antonio Texas
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Enjoying model rocketry since 1977.
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Sorta-almost...

The rear body tube separates at the base of the nose cone. The entire forward body, including the spindly posts, remains as one piece. It might be a good idea to use an extra-long Kevlar thread to connect the two sections, perhaps 5 or 6 feet long. It might also be a good idea to attach the parachute closer to the lower body than to the upper body, allowing the upper body to hang well below the canopy.

And yes, it is somewhat fragile, but it should land relatively gently with the 16" parachute. RockSim suggests that the landing velocity (Vl) is about 11 FPS with a C6-5. Empty, RockSim says the Vl is about 9.9 FPS. That's better than most of our models under normal conditions.

I may just have to build this one to satisfy my curiosity...

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Craig McGraw

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SAM 0044
AMA 352635

...And as I look again at the RKT file, I just noticed something strange that I did not see when I posted it earlier. The margin number with a C6-7 has dropped below the minimum of 1.00 -- it's currently at 0.48, which RockSim says is 'marginal'.

I'll tweak it a bit to get the margin back up above 1.00...

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Craig McGraw

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SAM 0044
AMA 352635

OK, here's the Mk II version.

Changes:

• Increased the main fins 10% (span is now 4.89", was 4.54").
• Lengthened the forward tube to 7" (was 5" long).
• Moved the forward pod farther, to 21.5" ahead of the rear NC (was 20").
• Moved the forward pylons 0.5" farther forward.

The new specs on this design are as follows:

Length: 29.50"
Diameter: 1.04" (ST-10)
Fin Span: 4.89"
Weight: 1.76 oz


B6-4......369'......Dv 13 FPS
C6-5......816'......Dv 22 FPS


All engines still reach flight V on a 36" x 1/8" standard rod.

Sorry for the confusion...

Attached Thumbnails

   

Attached Files

SRV Feynman Mk II.rkt (214.3 KB, 102 views)

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Craig McGraw

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SAM 0044
AMA 352635

Looks kewl Rear eject..sorta? I thought that you had some quantum physics means of getting the ejection gases up to the upper tube.Going for the 'particle entanglement' change method?

You do know of Richard Feynman?

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Jon
SAM #0396
BAR 02/07
NAR 86940
KF4GUL
Aim high, fly straight!

Yeah, somewhat...

He blew everyone away on the Rodgers' Commission looking into the Challenger accident when he dunked that piece of O-ring into his water glass and showed how the rubber lost its ability to make a complete seal when the temperature dropped down to 32-34 degrees.

Sealed the issue for everyone who had been second-guessing the engineers...

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Craig McGraw

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SAM 0044
AMA 352635

Different Feynman..This is the Richard Feynman I was referring to. He died in 1988.

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Jon
SAM #0396
BAR 02/07
NAR 86940
KF4GUL
Aim high, fly straight!

So you named it after a Texas blues man (Stevie Ray Vaughn) and a physicist?

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I love sanding.

No, that's the same guy. The Challenger disaster was in 1986.

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John Thro, NAR #84553 SR
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