That's what I'm waiting for, too. Those 30 sketches need to get validated with RS9 before I can add them officially to the list. That doesn't stop me from sketching with pencil and paper, though...

__________________
Craig McGraw

BARCLONE Rocketry -- http://barclone.rocketshoppe.com
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SAM 0044
AMA 352635

BTW, *way* cool!

I can see that sketching on paper doesn't limit you to what you can do (even by jumping through hoops) in RockSim.

(I just sent you some propaganda for the BARCLONE blog.)


Cheers,

__________________
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

You'll fit right in, Bill. We have a room and a jacket waiting for you...

The only issues I see immediately are, as noted, the single pylon, and the use of 2 E9s for power. Estes Es are notoriously weak, with less power than a D12 for getting off the pad. I would think a composite E (SU or RL) would be a better choice.

As for the pylon, a single plywood or (autoclaved) CF support column should be sufficient if you use a TTW attachment at the ring. This would mean the ring needs to be a laminate of two or three thin layers, and maybe needs to also be made from (autoclaved) CF. I am more concerned with the ring pulling off the pylon than I am with the pylon flexing or pulling out of the BT.

I like the idea of a single-pylon ring ship, and would love to see it done for A-C class motors. I'm sure it's possible; it's just a matter of good construction and the proper materials being used. Remember that RT ships are high-drag, and you'll never get a lot of performance from one. You will get a lot of joint stress and vibration on that pylon-ring attachment point.

Watch your acceleration numbers in RS. This column in the simulation doesn't get a lot of attention usually; in the case of your RT ship, though, you want to minimize this number somewhat. Watch the recommended launch guide length. If it goes over 48", you'll need a tower. You might also think about adjusting the power up or down to achieve flight V at or below 40" of guide. Too high an acceleration number could tear that ring right off the pylon by the time it gets off the end of the rod.

__________________
Craig McGraw

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SAM 0044
AMA 352635

Craig,

Your "sketched" designs are incredible. Can't wait to see them come to life in RS9. The new "pod" feature in RS9 is going to open up so many new design possibilities. I'm also curious to see how many of the previous designs will be reworked by the designer to achieve what they originally envisioned.

Already have RS9 first on my Xmas list !

... Bill

Jim,

Thanks! Yeah, strength of the main pylon is definitely a design concern. I tried to mitigate this by using TTW fins supports at both the body tube and ring fin mounts. The ring fin is actually two rings seperated by about .25"/.5" inches. There is a mass object at the center tube which reflects the weight of the small fins (7) that would seperate the inner and outer ring fins. I also used basswood in place of balsa, but maybe aircraft ply would be a better choice.

Thanks for the welcome to the asylum! I hope I can contribute to the cause and keep up with you guys!

... Bill

Thanks Jay! Appreciate the welcome! I hope to post some more designs in the near future. I have lots of hand-drawn doodles and sketches (although not as creative as the ones Craig recently posted.) First up will be a down-scale of the Chronos for C-engine.

... Bill

Craig,

Thanks for the welcome and feedback on my Chronos design.

Yeah, pylon strength is a concern. My experience has been limited to black powder engines, but I agree designs of this size / weight are probably more suitable for composites.

I posted some specifics about the single pylon design in a response to Jim. I did try to strengthen the fin mounts. I hadn't considered sheer force.

I'm going to work a "down-scale" C-engine version like you suggested. I can use it as a boiler plate to work out the single pylon design before moving onto mid-power.

Thanks for the feedback on acceleration / velocity numbers. Exactly the type of feedback I was looking for. Is there a general rule of them for acceleration and velocity numbers off the rod?

Thanks,

... Bill

The general recommended minimum is about 40 FPS safe flight V off the end of the rod. Anything below that is asking for trouble. I don't have my Handbook nearby, but if you notice in the RockSim settings, it has something like 38.99 or 39.99 FPS as the default threshold velocity. That "minimum launch guide length" number is a calculation of where RockSim says the model reaches this velocity. You then compare that number with a typical 36" or 48" launch rod (standard Estes pad). If it exceeds that length (minus about 6", since you lose some at the bottom for attaching the rod...) then you need to increase the power of the motor until the MLGL is within the actual length of the rod.

__________________
Craig McGraw

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SAM 0044
AMA 352635

Presenting the "Terra Nova Probe"...

ST-10 main diameter, about 28" long. The section behind the forward crew compartment is a reduction to ST-7, with "cooling fins" spanning the distance between the transitions. A screw eye is attached to the lower transition, and the 18" parachute packs into the main body.

It has some "Spacemaster" style elements, but I added the four ST-5 pods to change it up. The pods use the "inlet cones" from the SST:Shuttle as tailcones.

The ring is a 1" wide length of ST-20, and has only the two downward-canted fins as attachment pylons. The two main wings are canted downward at the same angle, and have 1/8" dowel tip probes. The pod pylons are TDC and BDC.

Power is 18mm, probably B and C since this appears to be a high-drag design.

Enjoy!

Attached Thumbnails

 

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Craig McGraw

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SAM 0044
AMA 352635

Craig,

Those cooling fins are a mutha to sand But it looks good. I like it.

Doug

.

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