Snecma C-450 Coléoptère

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BigMacDaddy

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This is my latest scratch build that I finished last week sometime... I did take a few liberties in the direction of stability -- slightly longer nose / body and slightly larger rear fins.

Have not launched it yet and I cannot figure out how to simulate that ring tail in OpenRocket. I did try a swing test and FWIW and it flew stable (nice whistle too) with the engine loaded and 2oz in nose (I'd like to go down to 1oz but maybe I'll stick with 2oz to be safe for maiden launch). With 2oz in nose and D12-3 engine loaded, CG is just about at front of the front most fins that connect ring tail to body. I am also planning to do another one with oatmeal container for the ring tail instead of 3D printed.

Anyway, I will post a video -- good, bad, or ugly -- when I launch it.

20210718_223840.jpg


20210718_223726.jpg


20210718_223759.jpg


c450_16.jpg
 

BABAR

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Very nice!

hope this fares better than the full scale original version


The ninth flight, on 25 July 1959, was planned to make limited moves towards entering horizontal flight; however, hindered by insufficient instrumentation and a lack of visual benchmarks, the aircraft became too inclined and too slow to maintain its altitude. Morel was unable to regain control amid a series of wild oscillations, opting to activate the ejection seat to escape the descending aircraft at only 150 m (492 ft).[2] He survived but was badly injured, while the aircraft itself was destroyed.

recovery space looks tight, and the tail wheels look a bit fragile.

best of luck!
 

cvanc

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recovery space looks tight, and the tail wheels look a bit fragile.
In other words, just like the original? 😊

This is a delightful bit of madness, following with interest. I hope your recovery isn't "historically accurate"!
 

Funkworks

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I like it!
beetle.png

(it's a bug aka beetle aka coleoptera)
 

BigMacDaddy

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Thanks folks for encouragement -- this is definitely a strange rocket that will certainly have some stability issues. The parachute winds up fitting half inside the nose and half in the body to give me enough room to buffer the ejection charge (using long Kevlar line as shock chord so hope that works).

I am worried that I should have notched my internal tube so that the fins would more securely connect to it since they need to support the weight of external ring fin which is not light. If the inside tube rips itself out of the ring tail that will be an interesting video - the resulting tiny finless rocket may still be stable with that super heavy nose.
 
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BigMacDaddy

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I am trying to drink more ice tea so I have more ring tail material to build one w/o the 3D printed rear end!!!

I'm so impatient for an update...
I watched that as well -- I cannot believe that there is no flight footage, just some photos but mostly on the ground...
 

BigMacDaddy

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Very happy to report that my Snecma C-450 Coléoptère flew great on its maiden voyage. The parachute did not deploy (stayed in the nose cone) but the model just bounced and did not suffer any damage (very tumbly without the 2+oz nose cone).

Have you guys figured out a way to stuff a parachute partly in body tube and partly in nose cone and still have it deploy? With this model I could maybe just put a smaller parachute and just let the nose cone deploy to drop with parachute and have the body tumble recover.


20210801_113903.jpg
 

lakeroadster

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Awesome model, awesome flight.

In regard to the chute issue.... try 2 smaller chutes... the lower chute will pull out the chute in the nose cone.
 

SDramstad

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We need a goony version of this
 

BABAR

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I am hoping to do a version with a cardboard ring tail but need to either eat more oatmeal or drink more ice tea!!!
A lot of nut “cans” are cardboard rings with metal bottoms.
 

Cape Byron

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All I know is I want one. Well, prolly three. ;)

Somewhere I have a manilla folder of 'Things I'd like to make' and I know there's a French aviation magazine in there with the C-450 featured.

Now that someone has made one I'm sure a lot of us would like to join in the fun.
 

BABAR

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Very happy to report that my Snecma C-450 Coléoptère flew great on its maiden voyage. The parachute did not deploy (stayed in the nose cone) but the model just bounced and did not suffer any damage (very tumbly without the 2+oz nose cone).

Have you guys figured out a way to stuff a parachute partly in body tube and partly in nose cone and still have it deploy? With this model I could maybe just put a smaller parachute and just let the nose cone deploy to drop with parachute and have the body tumble recover.


View attachment 475276
You may need to add nose weight in the cone forward of the parachute, theory being the ejection forcibly ejects the nose cone with the chute inside, the kinetic energy of the nose cone (exaggerated from the extra nose cone weight) allows it to keep traveling forward while the shock cord extracts the chute inside the cone. The chute DEFINITELY needs to be loose in the nose cone, this is one of the few times where it MAY be reasonable to wrap the cord around the chute just to keep it bundled. Usually I avoid that because sometimes it keeps chute from “unwrapping.”

the plus side is the extra nose weight, particularly when placed at the nose cone apex, adds to the rocket stability by pulling CG forward. You DO Need a firm attachment point for the nose cone shock cord, this is where drilling holes, placing a dowel across the cone, gluing it in, and sanding smooth the extenders protrusions works well. You could potentially combine it all, drill holes each side forward end of cone, pass a dowel trough one side, pass it through a metal nut for weight on the inside and attach your shock cord, then pass the dowel at the other side. Glue it on the inside (epoxy or gorilla glue, if epoxy maybe hang the cone nose down in water so it doesn’t melt the cone). Cut off the external dowel parts and sand it down to the surface, once primed and painted you won’t even see the holes, and Bob’s your uncle!
 

BABAR

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Congrats on a great scale design that flies well!
 

BigMacDaddy

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Bob’s your uncle!
I always liked that saying -- I had an English girlfriend back in the day and when I heard her say "Bob's your uncle" it just made no sense to me so I loved the Englishness of it.

I actually had done what you said and assumed it would work as you describe. There is a 2oz weight in the nose cone so I assumed it would fall like a stone and that would jerk the chute out from both directions. I may have made my shock chord too long or not made chute loose enough in nose cone.

There is not much space in the body for the chute and between the weight in nose and the weight of the model I calculated I needed a relatively large chute (18" if I recall). I think I will simply put a smaller chute and just attach it to the nose cone so that heavy bullet does not come down too fast. I think I can let the body tumble down and bounce like it did on the maiden launch.
 

BABAR

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I always liked that saying -- I had an English girlfriend back in the day and when I heard her say "Bob's your uncle" it just made no sense to me so I loved the Englishness of it.

I actually had done what you said and assumed it would work as you describe. There is a 2oz weight in the nose cone so I assumed it would fall like a stone and that would jerk the chute out from both directions. I may have made my shock chord too long or not made chute loose enough in nose cone.

There is not much space in the body for the chute and between the weight in nose and the weight of the model I calculated I needed a relatively large chute (18" if I recall). I think I will simply put a smaller chute and just attach it to the nose cone so that heavy bullet does not come down too fast. I think I can let the body tumble down and bounce like it did on the maiden launch.
@mbeels is a fan too.
 

BABAR

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I always liked that saying -- I had an English girlfriend back in the day and when I heard her say "Bob's your uncle" it just made no sense to me so I loved the Englishness of it.

I actually had done what you said and assumed it would work as you describe. There is a 2oz weight in the nose cone so I assumed it would fall like a stone and that would jerk the chute out from both directions. I may have made my shock chord too long or not made chute loose enough in nose cone.

There is not much space in the body for the chute and between the weight in nose and the weight of the model I calculated I needed a relatively large chute (18" if I recall). I think I will simply put a smaller chute and just attach it to the nose cone so that heavy bullet does not come down too fast. I think I can let the body tumble down and bounce like it did on the maiden launch.
something a little less cosmetic is an external shock cord mount on the rear of the rocket (can be removed for display purposes, and stick it on the launch rod side so it isn’t as ugly at launch.). You run it between the nose cone and the body tube when you pack. The main segment of the rocket will dangle tail up during descent, so the tube takes the impact instead of your fragile looking landing gear.
 

tab28682

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Very happy to report that my Snecma C-450 Coléoptère flew great on its maiden voyage. The parachute did not deploy (stayed in the nose cone) but the model just bounced and did not suffer any damage (very tumbly without the 2+oz nose cone).

Have you guys figured out a way to stuff a parachute partly in body tube and partly in nose cone and still have it deploy? With this model I could maybe just put a smaller parachute and just let the nose cone deploy to drop with parachute and have the body tumble recover.


View attachment 475276
Stuff as much of the shock cord as possible into the nose cone, ahead of the parachute bundle.

At separation, the bundle of shock cord deploying will pull out the chute.
 
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