Tri-Ceptor Scratch build

weird. Very good, but weird.
Great video, BTW

My daughter does a great job on the video, especially considering the small viewing screen she has to work with, I'm glad she kept recording the fall, eventually it goes behind a camper so you can't see the landing so I just stopped the video there. It would be neat if that is a repeatable recovery mode, but I hope I never find out

BABAR said:

weird. Very good, but weird.
Great video, BTW

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BABAR said:

That recovery throws me. How does a rocket which is stable on boost, after burning off all the propellant ( which if anything should make it MORE stable/nose heavy) transition to horizontal spin recovery? It obviously DID happen, and given such a nice rocket I am glad as I am sure you are that it happpened, but I don't understand it. Did the motor mount shift back?

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Not sure where I read about it here on TRF, but there is a method of recovery called something like "back sliding/gliding."

Here is a good description by Peter Alway, https://web.archive.org/web/20071015035108/https://members.aol.com/petealway/srrg.htm

It also talks about the spinning, I'm not sure yet how the open middle helps/hinders this but I'll keep reading....

frank

Great article. Very cool. Horizontal spin is easy if you eject/separate the nose cone/weight, but clearly very tricky to achieve otherwise. I think now I understand what you meant about the flow between the tubes altering the "center of lateral area." Well, maybe sorta I understand.

Of course, the irony in all this is that you, the glider meister should be the one to end up with an unintentional glide recovery!

I know, when I came up to the RSO table, they said there weren't any wings, I guess I just can't help myself

BABAR said:

Of course, the irony in all this is that you, the glider meister should be the one to end up with an unintentional glide recovery!

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I did some more reading, In summary, at high angles of attack the 2d cutout Cp model drives the way the rocket recovers, and at low angles of attack the borrowman CP is appropriate, and it is possible to have a design where you are stable at low angles of attack on boost, but with a pitching manouver to get high angle of attack to be stable sideways during recovery. They state that if the burnout CG is within the top 40% of the distance between the 2d side view(cardboard cutout) cp and the borrowman cp your chances of sideways/glide recovery is solid. My borrowman Cp is 51" from the nose and the 2d cutout Cp is 39.9" from the nose, so a burnout CG of anywhere between 39.9" and 44" from the nose should be good.

I've modeled the side tubes with thick fins, however that should not impact the cardboard cutout CP. In my rocket with the G65, the burnout CG is at 39.2" so this is slightly ahead of where Alway et al would predict. point is I'm slightly ahead of the point they predict would allow a sideways recovery but not significantly so.

There was little to no wind and I did not have a destabilizing/pitching action either to put it into a sideways angle of attack. So did I get lucky?

Frank

burkefj said:

There was little to no wind and I did not have a destabilizing/pitching action either to put it into a sideways angle of attack. So did I get lucky?

Frank

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Again, that video was great. The rocket DID arc over normally, so it didn't just do a perfect upright decel, stop, and backslide (one of the boost to glide transitions mentioned in article)

Ejection appears to have popped, but nose didn't come out completely (did it come out AT ALL when you recovered it?) If it came out a bit, maybe some asymmetric thrust flipped it sideways, but don't see that on the video.

Even if the rocket fin/body/nose configuration WAS appropriate for this type of recovery, without an intended input to flip a transition (like the sideports in the article), I don't see a reliable system here.

IOW, yup, you got lucky!

As you have noted, you are too smart to try it again with this rocket.

Might be a cool design to try again. Obviously no point in finishing a rocket to the Nth degree as you do with your designs for something that may come in ballistic.

Other BIG problem with such experimentation (and kind of makes me wonder where/how they did their experiments, NOSE DIVE recoveries as reported being somewhat frowned upon by RSOs) is the significant probability of failure, so where do you launch it?

I agree that the video does apear to show a "pop" and I thought I saw it in person, but there was none, the nose was not moved and the ejection charge was intact, in fact the black powder was intact, the ejection charge hole had a rubbery blockage that did not allow the charge to be ignited even though the delay burned, I assume the smoke/pop we saw was just an artifact of the delay burning out or something.

Frank

Gary Goncher captured some great photos of the Tri-Ceptor flying and getting ready to fly:

Tom Beach got a great photo on an F-32 flying at NARAM this year.

Very interesting stuff. It begs the question: Could a rocket be designed to induce spin for recovery?

Yes there was such a design using rotor blades cannot remember it’s name but I do recall reading if you are ever out by the mojave space port there is one old rocket model standing there one display with such a design
Suffice to say it was designed before its time

Crawf56 said:

Very interesting stuff. It begs the question: Could a rocket be designed to induce spin for recovery?

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Just remembered the idea you are thinking of was explored as "Roton" a 1990's self landing rocket/helicopter hybrid

I think what was being asked was could you reliably induce a rocket to spin sideways as a stable recovery mechanism, not a helicopter type recovery, but similar to the super roc sideways glide recovery, could you induce a spin to help stabilize sideways and recover softly.

burkefj said:

I think what was being asked was could you reliably induce a rocket to spin sideways as a stable recovery mechanism, not a helicopter type recovery, but similar to the super roc sideways glide recovery, could you induce a spin to help stabilize sideways and recover softly.

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Okay in that case I’m not really sure what your talking about to be honest

Proconquer said:

Okay in that case I’m not really sure what your talking about to be honest

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If you look at Post #28, there is a video showing a 'tumble' recovery. The parachute does NOT deploy on the Tri-captor rocket; instead, the rocket is spinning about its nose/tail axis. (Would be called "roll axis" on an airplane.)

The spinning effect of the 3 smaller 'joining' tubes produces an aerodynamic lifting effect, greatly slowing the rocket descent. See the Peter Alway article in Post #34. [Edit: I don't think this is a valid link anymore.]

Like this?

https://www.rocketryforum.com/threads/bail-out-bill-and-the-horizontal-spin-recovery-rocket.147210/

BABAR said:

Like this?

https://www.rocketryforum.com/threads/bail-out-bill-and-the-horizontal-spin-recovery-rocket.147210/

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I especially like the tube around the fins, to protect the fins on landing. Very good, sir!

The Magnus Effect. Here is an example of an RC airplane......that looks like an old push lawnmower: