High speed recovery

Discussion on ground control/GSE and recovery equipment. This includes launch pads, triggers, chutes, streamers etc. Includes other items such as simulation and other computer software, etc.

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cryoscum
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High speed recovery

Postby cryoscum » Tue Jun 24, 2014 4:48 pm

1.jpg
1.jpg (54.62 KiB) Viewed 2509 times

Not so easy to employ on a minimum diameter rocket weighing 3kg...
AMRS L3 | NAR L3 | QRS 089 | MDRA 224
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Total impulse for 2016: 32,458 Ns (thus far)
Total impulse for 2015: 84,231 Ns
Total impulse for 2014: 40,757 Ns
Total impulse for 2013: 62,927 Ns

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SpaceManMat
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Re: No Big Deal

Postby SpaceManMat » Tue Jun 24, 2014 5:24 pm

ROCKet STAR wrote:I can see where you are coming from with this, however I really to think that this approach could do more harm than good. The ballistic coefficient of these high performance rockets is generally high, and as such in the the thin air that they fly to, if they don't seperate in order to increase their drag, they reach phenominally high speeds very quickly. Trying to separate a rocket and deploy a parachute at that speed, will likely result in a destroyed rocket, blown out parachutes, and a bad day for the flier. DDT's descent rate under drogue at 190fps (208km/h) is by no means slow. Faster than that I imagine that potential for problems when the main is released is going to to increase quickly.


Very true, the altimeter would have to have over speed or anti ballistic detection. This would fire the drogue if the speed was getting out of hand. A facility that I believe they should have already as this could be used conventionally to detect a failed drogue and fire the main. It's not just about speed either an intact rocket will come down straighter.

cryoscum wrote:
1.jpg

Not so easy to employ on a minimum diameter rocket weighing 3kg...


No it won't be easy. There is probably a few ways to add a rearward drag device, but I think by extending a traditional av bay a bit you could effectively deploy a device rearward.
QRS: 124
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Re: No Big Deal

Postby jase » Tue Jun 24, 2014 5:31 pm

I'm loving where this discussion is heading!

8)
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Re: No Big Deal

Postby air.command » Tue Jun 24, 2014 6:07 pm

Interesting conversation. On the high speed ballistic return could you deploy small fins near the nose that would shift the CP forward causing the rocket to become unstable and cause it to tumble. When it slows down enough, you could then deploy the drogue and main as normal. I know that there would still be huge forces involved on the airframe if you tried to get it to go unstable at high speed, but it should be subsonic in the lower atmosphere.

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cryoscum
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Re: No Big Deal

Postby cryoscum » Tue Jun 24, 2014 6:59 pm

Great idea, George, but wouldn't it be hilarious if you shredded on the way down!!
:lol: :lol:
AMRS L3 | NAR L3 | QRS 089 | MDRA 224
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Total impulse for 2016: 32,458 Ns (thus far)
Total impulse for 2015: 84,231 Ns
Total impulse for 2014: 40,757 Ns
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Re: No Big Deal

Postby b-h » Tue Jun 24, 2014 7:49 pm

Some time ago an amateur rocketeer built a rocket with high drag recovery petals aft and a long nose spike for lawn dart style recovery, I think it was Derek Deville, maybe??

Also this, not really minimum dia or hp but inventive

https://www.youtube.com/watch?v=jdqse5T ... e=youtu.be
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Re: No Big Deal

Postby Iconia » Wed Jun 25, 2014 2:42 am

This club gets me to do a lot of climbing through my old junk pile.

Here's an old classic. The Pod2e. My second generation, 70mm test bed launcher for my experiments.
It featured an aerobraking module for moving the CP up to the CG which causes the rocket to fall basically sideways, though never perfectly sideways.
I found the trick was to get the CP as close to the CG, but with going forward of it or it would wobble around alot.
Image

This second gen test bed used a Raven 3 instead of recovery being handled by it's main computer network (an Arduino Mega commanding PICs and Arduino Nanos), and so required a very simple AeroBrake Deploy mechanism.
As you can see, it used rubber bands to deploy, and solenoid latching (nail pulled up to release tie wire loops) which was very primative, but could be actuated by one of the Raven 3s channels.

Image

The problem was that I had to design my test modules to a certain weight and length to get the CP/CG match during recovery.
My third gen test beds were pure Arduino which allowed me to use RC servos for deploy which gave "proportional AeroBraking" capability. Literally I would calculate how open the brakes needed to be to position the CP correctly. Both third gen examples got destroyed on missions, but due to the experiments they were carrying.

Of course, proportional AeroBraking still causes limitations on configuration, especially with heavy nose cone mounted experiments, and so I have a better idea for the forth gen 70mm, though it will probably be used on 40mm first, that should solve the problem.

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Re: No Big Deal

Postby Iconia » Wed Jun 25, 2014 2:07 pm

Was having a think last night about the amount of strain it would cause if you opened frontal aerobrakes or destabilizing fins at speed (as you would if you wanted it to plummet before deployment). Would put enormous bending forces on the air frame. I personally never tried it that way, only ever deployed at apogee.

A safer option would be to use rear eject drogue. We used that system from 2006-2010 for my Pod2/Glorious Soviet Proton rockets.
Excuse the quality of the on board footage. It show how far SD cameras have come. I was so trilled at the time not to have to worry about video distortion due to the tape speed changing with the G force.



If your not to trilled about firing your motor out the back mid-flight, you could try a trick Alan and I had a few goes at.
We mounted a motor in the nose cone to act as a retro rocket. We were trying to use it as a primary recovery system so that the rocket would be at less than 1m/s when it hit, but the motor would never ignite at a consistent rate and so was always to early or late.

If you were simply using a retro motor to slow the rocket down for main chute deployment, it would totally work.

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Re: No Big Deal

Postby cryoscum » Wed Jun 25, 2014 2:32 pm

Iconia, throwing the motor out the back is an old trick. We also did it on smaller rockets when we were still chasing high Mach numbers in low waivers (slow-down immediately after boost) and I gave it a run on Mad Max when I test flew it at Red Glare (April 2013) on a small M, as an apogee drogue device. It works fine in a situation where you have a full length airframe, but is clearly impossible in a configuration like No Big Deal, hence no point in going there at all.
As for aero brakes made up of flaps cut into the airframe, I'm sure it'll work OK for LPR cardboard models, but I won't be cutting big holes in an airframe intended for a Mach 3 flight.
AMRS L3 | NAR L3 | QRS 089 | MDRA 224
AMRS Technical Advisory Group

Total impulse for 2016: 32,458 Ns (thus far)
Total impulse for 2015: 84,231 Ns
Total impulse for 2014: 40,757 Ns
Total impulse for 2013: 62,927 Ns

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Re: No Big Deal

Postby Iconia » Wed Jun 25, 2014 10:52 pm

Fair enough.
Even for card board LPR, I had to put load bearing struts in between to transfer the forces forward and aft of the brake slots.
Might be too hard on minimum diameter M rocket.

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Re: High speed recovery

Postby admin » Fri Jun 27, 2014 7:10 pm

This post has been split as the current information seems suitable for a discussion on high speed recovery.

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Re: High speed recovery

Postby SpaceManMat » Fri Jun 27, 2014 9:40 pm

Great we've broken a thread.

The idea I had was to use an expanding collar of some sort that would be contained behind the electronic section of the av bay. The av bay itself would have an additional section on the aft for the collar to sit within in its compressed state. The collar would be restrained from expanding by the inner diameter of the body tube.

At or soon after apogee the av bay is slid partially forward to expose the collar and allow it expand. Once expanded the collar fits over the outer diameter of the body tube and is forced reward to the fins by drag. The collar would have drag devices attached to it. I thought that either 3 streamers or 3 small deflectors would make suitable drag devices, these would be spaced between the fins.

To move the av bay a motor driven worm screw would probably work best. The advantage with this is that you don't have to worry about the efficiency of black powder at high altitude.

Also when the collar expands there is the possibility of it falling forward if there is not enough drag straight away. To prevent this I thought that you could have 3 small pop out fins ahead of the collar which would be uncovered first as the av bay was slid forward. These will also add a bit of drag and definitely add to the cool factor.

That's basic gist of my crazy idea to effectively place a drag device at the rear of a mb rocket. As Nic said its not easy. The collar is obviously the most critical part to design and manufacture.
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 13,647 feet
Fastest Flight: Mach 1.55
Largest Motor: CTI 1115J530 IM
Current Project: X Wing


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