Low-power rocket with automatically deployed speedbrake

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Cookie the Dog's Owner

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This is a doodle I came up with based on an idea that's been rolling around in my brain for a while. It's a two-engine cluster in a BT 60/70 size tube, with one short-delay engine (e.g. B6-2) and one long-delay (e.g. B6-6) of the same impulse rating. When the short delay ejection charge fires, it causes two speedbrake panels to pop open, bringing the upward coasting phase of the flight to an abrupt end. As the rocket descends, the long delay charge fires and pops open the parachute.

In an attempt to be clever, I call it "Braking Bad."

Braking Bad.jpg

I'd appreciate your comments, critiques, and/or ruthless ridicule.
 
Hmm......interesting concept for sure.

I'm curious to know how the brakes are going to be attached, secured, and have some kind of stop so they don't simply flip over against the fin can. But, it's interesting!
 
Interesting idea. I'd be really worried about the brakes getting ripped off at any reasonable speed. Those hinges are going to be under a LOT of strain. I would almost go the other direction. Flip them 180 degrees, and have their "normal" position be the breaking position (pushed out from the body). Use some kind of restraint to pull them in flush for flight. The ejection charge trips the retention, and they pop out to their "normal" position. Since they are flipped 180 degrees, the friction they generate will want to push them back flush, but this is much more kind to the devices in terms of forces acting on them, and worst case is they get pushed flush instead of ripped off.
 
This is one of the more unique ideas I've seen in a while. You have some serious engineering challenges here as others have pointed out however I think it can be done. Probably going to involve a lot of flights, tinkering and so on to get it right. Keep us updated as this sounds like something I might like to try...

Now you might want to consider moving the air brakes as far aft as you can because the extra drag that far forward may induce instability but I really can't say for sure. Kind of a gut feeling I guess.
 
It's a great idea. I've been working on a similar idea for HPR.

It occurred to me that building an extremely sleek and areodynamic rocket that flies very straight and to then break it in half, wreck the aerodynamics, put out a chute and watch it drift all over the place, was in fact not the best way to do things. Far better to keep the areodynamics intact and simply slow the rocket down. The big challenge is how do you achieve this in a minimum diameter rocket without adding too much weight as these are of course the very high fliers that will benefit the most.

Not sure if this is the reason behind speed breaks or are you just going for the cool factor?
 
Before I got out of rocketry 13 years ago I had designed a "Snake Eye" bomb type rocket with petal type air brakes. I started a thread on Rocketry Online about it but never built mine. Someone there had actually built one about BT60 sized. Your thread and the one on the umbrella chute got me thinking about it again. Over the weekend we attended our first launch with the kids at Moffett field. Afterwards we were able to take a tour of a P3 Orion and they had the sonobouys on display. They also use a petal type air brakes. I explained how it worked to the kids and told them about my rocket idea and it got the creative juices flowing again. I've got it all drawn up in Open Rocket. I just need to order the parts.

Here's a picture of what I am thinking about:

MK-82Snake-eyeBombs.JPG
 
It's a great idea. I've been working on a similar idea for HPR. . . . are you just going for the cool factor?

At last year's NASA Student Launch project in Huntsville, one of the college teams was flying a rocket with an altimiter-controlled speedbrake in an effort to hit the target altitude (5,280') spot-on. Don't think I ever heard how close they came, but I liked the concept.

I was also thinking in terms of being able to launch a clustered rocket with lots of fire and smoke in a relatively tight field and still get it back.
 
Now you might want to consider moving the air brakes as far aft as you can because the extra drag that far forward may induce instability but I really can't say for sure. Kind of a gut feeling I guess.

As shown in the sketch, the idea is to have the brake "chamber" right above the short-delay engine's thrust block. I suppose you could put it even lower, right down between the fins, using some sort of duct/baffle arrangement.
 
Maybe change the fin shape, and put the air brakes above the fins so that when open the fins support them. Would make for an unusual fin shape though.
 
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