Anyone tried compressed air for ejection?

[Nick@JET]

Just thinking of what the future of rocketry looks like as far as ejection charges. I realize CO2 is available and certainly 4F is obtainable enough by purchasing 25lbs at a time but as a fairly newcomer to HPR (3yrs) it appears that will not get any easier.

So has anyone ever tried this or know or know of a system?

 

[dhbarr]

I'd think the hardest part would be releasing the pressure. Maybe a fill valve on one end and a screwdown / snapring replaceable burst disc assembly on the other? Can't imagine it could mass less than existing co2 and still maintain the safety margin.

 

[dhbarr]

On second thought, an assembly that takes co2 pellets could work fairly well, possibly a sub-assembly that goes inside an RMS 18/20 case and/or replaces the closures.

 

[NateLowrie]

Just thinking of what the future of rocketry looks like as far as ejection charges. I realize CO2 is available and certainly 4F is obtainable enough by purchasing 25lbs at a time but as a fairly newcomer to HPR (3yrs) it appears that will not get any easier.

So has anyone ever tried this or know or know of a system?

The main problem right now with compressed air is releasing it. CO2 cartridges require a large amount of force to puncture and all the systems are activated chemically with an ematch and pyrodex. You can do a valve but it requires weight and the avionics interface might be tricky.

I expect that the future is probably electrically actuated systems.

 

[Incongruent]

I think a solenoid valve should work for releasing pressure and is used on some paintball guns and such. (For an electronic system.)

 

[jonno]

I'm new at this one however would
a fuel garage & usage of there tyre
hose help? it would look weird however it's a thought, set at PSI
no idea. But it would give people
a really good look, at what's rocketery is about. just a thought
however. May try it myself,please
anyone give me advice.Australian
rules completely different than you'rs.jonno

 

[OverTheTop]

Our full scale V2 (46' high) used compressed gas (CO2) to separate the three sections. Special valves and pressure cylinders (6" diameter) were made which performed admirably. One tank was aluminium, the other carbon fiber. One tank held 20bar, the other 30bar. The entire rocket weighed 400kg on the pad, so they provided a decent push (have a look at the video) for splitting the airframe.



https://www.facebook.com/worldrecordrocket/

There was even an umbilical for filling on the pad, which was cleverly detached using a pneumatic release mechanism remotely.

I have to say, as one of the recovery guys on the project, it was good to see the separation and recovery work [sigh-of-relief-icon].

It is overkill for your needs, but shows you what is possible and it might interest you. Enjoy!

 

[MClark]

I have flown a compressed air system.
Air tank a one liter plastic soda bottle with 120 psi.
I made an adapter with female threads to match the bottle and other end male garden hose thread. Light plastic valves for garden hose are available at Home Depot. The release valve is a burst disc made from the heavy tape use on the leading edge of aircraft wings. Disc is clamped to the he's valve with a cap with a hole drill fo air release. Another cap has an air hose quick release fitting to fill tank.
In operation, tank, adapter, valve, and fill fitting together. Valve open, fill with air, close valve, remove fill adapter, put on burst disc/cap, open valve to test seal. Tape will dome with pressure.
A electric match is against burst disc, it must be in direct contact, and taped. When altimeter fires match it heats plastic burst to failure releasing air.
Will fit in a 4" airframe tube.
Bottle can be used as a piston.


Sorry, the description a bit rambling.

M

 

[OverTheTop]

I have flown a compressed air system.
Air tank a one liter plastic soda bottle with 120 psi.

Clever system

 

[rocket_troy]

Our full scale V2 (46' high) used compressed gas (CO2) to separate the three sections. Special valves and pressure cylinders (6" diameter) were made which performed admirably. One tank was aluminium, the other carbon fiber. One tank held 20bar, the other 30bar. The entire rocket weighed 400kg on the pad, so they provided a decent push (have a look at the video) for splitting the airframe.

View attachment 305660

https://www.facebook.com/worldrecordrocket/

There was even an umbilical for filling on the pad, which was cleverly detached using a pneumatic release mechanism remotely.

I have to say, as one of the recovery guys on the project, it was good to see the separation and recovery work [sigh-of-relief-icon].

It is overkill for your needs, but shows you what is possible and it might interest you. Enjoy!

How the V2 separation system worked : [video=youtube;y7HT6eOhUOU]https://www.youtube.com/watch?v=y7HT6eOhUOU[/video]

My HPR deployment device will happily work with any gas you feed it with providing there's enough energy within the system https://propulsionlabs.com.au/Pyroless_Release/ which means you'll need kinda CO2 type pressures (say 600Psi) for a 4" airframe deployment which (if you wanted to use compressed air) would require a reasonably high pressure compressor (hard to find) or a HP hand pump like one of these
For a, say, 60mm airframe, I'd probably get away with 150 psi/10 Bar fills.

Troy.

 

[OverTheTop]

Thanks for posting that Troy! Your engineering on this for the V2 worked a treat