Retro Thrust recovery

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n27sb

N27SB
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Has anyone ever used a rocket motor as a retrograde to slow a rocket during decent prior to a parachute for recovery?
 
It's ignited with a length of safety fuse.
Burn rate of fuse determines the length.
Delay time is calculated on a cd with old sim software.
Old like in Windows XP.
 
Has anyone ever used a rocket motor as a retrograde to slow a rocket during decent prior to a parachute for recovery?

That would only be of value if you are choosing to deploy the chute at some point other than apogee.
In which case, the reliability of this "re-entry burn" method would depend on the rocket always coming down vertical, tail first, and fast enough to be aerodynamically stable during "re-entry burn".
Otherwise, you risk going into "cruise missile" burn right before chute deployment, which would defeat the purpose of the experiment.
 
It's ignited with a length of safety fuse.
Burn rate of fuse determines the length.
Delay time is calculated on a cd with old sim software.
Old like in Windows XP.
Have you ever seen one
 
That would only be of value if you are choosing to deploy the chute at some point other than apogee.
In which case, the reliability of this "re-entry burn" method would depend on the rocket always coming down vertical, tail first, and fast enough to be aerodynamically stable during "re-entry burn".
Otherwise, you risk going into "cruise missile" burn right before chute deployment, which would defeat the purpose of the experiment.
It would come down nose first with the retro in the nose
 
Have you ever seen one

Yep, in my build pile:
1204200734[1].jpg

Haven't seen one in action though.
This is a rather rare, obscure bird.
Agree that electronics would be more reliable than a fuse.
Dual event altimeters and e matches are cheap and readily available.
I bought the safety fuse from EBay.
Why don't you fashion one of your own design?
BTW the purpose of the retro motor is to reduce parachute drift in the days before the JLCR.
 
Your quote: I like the unusual, the off beat, the avant-garde. No 3/4 FNC for me

Figures you would have one. Believe it or not, they are still available for $39.00.
I plan to do a scratch build.
 
Joe Barnard's work on model rocket Thrust Vector Control is several orders of magnitude more complicated and expensive. He actually had a TVC unit for model rocket engines that he sold for a while on the BPS website.
Way out of my budget.
 
I wonder how much simpler Joe's rocket would get if he landed it nose down.

I have the BPS rocket, and it almost works (really needs AT G8 or G12 motors, as F10 is very borderline).
When it works, to goes up vertically, with moderate sideways drift, downwind.

There is no traditional apogee.
Depending on the exact thrust profile, the rocket stops ascending and starts drifting down under partial thrust, or tumbles with out thrust. Attempting to controllably swap ends to point the nose down would be an additional complication.
 
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After the Retro burn

I would think that would present a fire danger and any rocketry organization would prohibit it. The launch area can be protected from fire by the established rules, but where the rocket may land is often up to the fates. Trusting everything to go right during recovery is up to the fates and having an open flame of a rocket motor during descent is a huge risk. What if the parachute tangles and catches fire when the motor is ignited? The landing area could very well have flammable material that a flaming rocket would start a fire.

I think it’s a dangerous idea that if NAR/TRA doesn’t already consider it contrary to safety, then they well should. As Barney Fife says, “You have got to nip it in the bud, nip it in the bud.”
 
I think it’s a dangerous idea that if NAR/TRA doesn’t already consider it contrary to safety, then they well should. As Barney Fife says, “You have got to nip it in the bud, nip it in the bud.”
So that means Joe Barnard is breaking the rules? And his TVC unit he sold is illegal?
And we all know how often Barney was right and Andy was wrong right?
:D
Seriously, even a standard launch can CATO and present a fire hazard.
Or go seriously off course and eject on the ground far from the pad, again presenting a fire hazard.
The kit fires the retro motor well above the ground. The provided cd has software that calculates the correct delay time for the fuse for optimal retro motor ignition. Adding electronics would further the margin of safety.
And chute ejection is standard BP blow. No more risk of tangling or burning that any regular rocket.
I would think that Barnard's TVC experiments would be far more likely to cause a fire on the ground since the retro flame is so close and there's no chute.
Even the simplest rocket can malfunction, but if we exercise due caution we can mitigate that.
My 2 cents.
 
There's another thread about someone trying full retrorocket landing without a parachute:
https://www.rocketryforum.com/threads/propulsive-landing.163043/and it features this video which is all kinds of awesome:

That’s really cool. Seems like the answer is pretty simple, that landing legs need a wider span, I think had it been about double what he had he would have “stuck” the landing. Rubber band deployed leg extensions held in place at launch with burn band or thread would be easy and reliable.

Flying limits would be pretty strict.

You need a landing zone that is completely non-flammable, as it comes down on a hot burning jet,

No appreciable wind. Any appreciable wind will blow this laterally potentially outside your landing zone and likely invoke enough lateral velocity to prevent you from sticking the landing.

Either no spectators or very few, all required to be attentive to launch.

I’d seen the BackDraft in rocket reviews.
Interesting photo here of author of review , quote“Photo 10: The author flees the scene” after manually lighting the fuse (the primary boost motor is ignited electronically)
5E934258-AA10-4614-9818-1DBE7D67A438.jpeg

https://www.rocketreviews.com/heavenly-hobbies-backdraft--by-dr-john-smolley-md.html
Other reviews here

https://www.rocketreviews.com/heavenly-hobbies-backdraft--by-dick-stafford.html
https://www.rocketreviews.com/heavenly-hobbies-backdraft--by-smolley-john.html
 
I would think that would present a fire danger and any rocketry organization would prohibit it. The launch area can be protected from fire by the established rules, but where the rocket may land is often up to the fates. Trusting everything to go right during recovery is up to the fates and having an open flame of a rocket motor during descent is a huge risk. What if the parachute tangles and catches fire when the motor is ignited? The landing area could very well have flammable material that a flaming rocket would start a fire.

I think it’s a dangerous idea that if NAR/TRA doesn’t already consider it contrary to safety, then they well should. As Barney Fife says, “You have got to nip it in the bud, nip it in the bud.”

Thank you for your input. All good points.

That is the reason I post all of my crazy ideas here. There is always an abundance of wisdom in regard to safety and function.

BTW, Barney was limited to only one bullet and he had to keep it in his shirt pocket for a good reason.

This idea may never fly but I view it as a challenge. In many ways it is similar to a Multi-stage/ Multi-event rocket and deserves all of the same safety devices such as lockouts driven by altitude, attitude, and acceleration.


Screen Shot 2020-12-05 at 8.30.19 AM.png
 
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Has anyone ever used a rocket motor as a retrograde to slow a rocket during decent prior to a parachute for recovery?
Yes, I had several flights a few years ago. I'll look for photos and post a bit later. I developed it into a two stage rocket. First stage ground launched on legs, second stage separated and ignited. The second stage was a typical rocket configuration and dual recovery. The booster came down "hot", ignited the retro to slow the rocket for 3 mains out of side bays. The booster used 38 mm motors and 29 mm for the retro. The 2nd stage was a G. I think the maximum altitude for the 2nd stage I got was about 6000'. All using electronic timing and altimeters.
One of the coolest things was the sound of the retro motor. The sound is much different than a motor during ascent. Also, waiting for the retro to fire because there is only a few seconds to spare.
 
Yes, I had several flights a few years ago. I'll look for photos and post a bit later. I developed it into a two stage rocket. First stage ground launched on legs, second stage separated and ignited. The second stage was a typical rocket configuration and dual recovery. The booster came down "hot", ignited the retro to slow the rocket for 3 mains out of side bays. The booster used 38 mm motors and 29 mm for the retro. The 2nd stage was a G. I think the maximum altitude for the 2nd stage I got was about 6000'. All using electronic timing and altimeters.
One of the coolest things was the sound of the retro motor. The sound is much different than a motor during ascent. Also, waiting for the retro to fire because there is only a few seconds to spare.
Thank you Richard,
Any info you can post is appreciated. Please feel free to PM me if it is something that you do not want public.
 
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Interesting photo here of author of review , quote“Photo 10: The author flees the scene” after manually lighting the fuse (the primary boost motor is ignited electronically)
That does not make sense. The fuse is supposed to be lit by the hot gasses from the booster motor, not manually lit on the ground.
EDIT: I checked the instructions again and both the booster motor and the safety fuse are supposed to be electronically ignited on the pad. Don't know why that dude had to manually light the fuse.
 
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