Hybrids 2022

[profmason]

The Mt. SAC 2022 liquids season is wrapping up. Major development was getting a test stand built on campus! Thanks to support from Dave Griffith from Rattworks the students have done 22x 38mm static tests (14 successful) with 6 different fuels compositions (Polypropelene, ABS, Polyethylene terephthalate, PLA, Nylon and ASA) Primary research has been in 3D printed grain geometries and characterizing the erosion rates of different 3D printed materials. The student design is based on Griffith's floating bulkhead and UC valve. The floating bulkhead is critical for the 3D printed materials as the combustion chamber length shrinks during the burn as the thrermoplastic goes through the glass transition. The Polyethylene terephthalate shows good promise as a fuel for hybrids and ease of fabrication. Two flight days with one success on the 38mm x 900mm motor. The student competition is coming up June 3-5 and they are prepping the 38mm by 1800mm motor. The students also were supported by Dave to fly a NOX / IPA biprop successfully to 11K which was a big deal for a community college team and the biprop is now on display at Norms hanger. While the larger biprop motor (75mm x 2400mm) had a failed static test(injector / preheat issues) last week, there is another test scheduled for tomorrow so that it can get flown before it gets too hot out at FAR. These students are scattering to aerospace programs all over SoCal but if the REU application is supported, the research program should continue next year.

We have gotten to know the good folks at Socal Nitrous and Race Fuels in Downey (just down the street from the old NASA plant) who have not just refilled our bottles but happily revalved and hydro tested old CO2 bottles with high flow NOX valves. We also found that no steel NOX bottles are allowed to be refilled in CA.

If anyone is planning to bring their hybrid out to FAR, let me know well in advance as I can arrange NOX and GSE.

 

[Hobie1dog]

hybrid experts at the college level, I'm impressed and envious

 

[CoyoteNumber2]

We also found that no steel NOX bottles are allowed to be refilled in CA.

Did that go into effect recently?

 

[Dave A]

Turns out that getting nitrous around here without doing the tank swap routine is looking like it isn't happening. Nobody I've talked with so far will fill a tank, just swap a steel one.

Not sure what tank you have but I had my 20# tank filled at Budds Creek, MD dragstrip by one of the vendors. Most larger speed shops do or at a large car drag race will have vendors to fill them. They will fill thr 2-20# AL cylinders not the big steel ones.

 

[mrwalsh85]

I know this isn't a classifieds thread but is there any interest in a 75mm Hypertek L tank with fill stem assembly? I have no need for it and our club has obsoleted our hypertek equipment (already sold).

Drop me a PM if so.

 

[G_T]

Dave, that's close to 2 hours from here in N. VA. I don't have a cylinder yet. I'd thought to get a B-50 or at least a B-35. A B-20 will only fill my motor once, and I'd planned to scale up to an EX N for next year which a B-20 wouldn't fill at all. Admittedly, a full B-20 would handle this M motor for this launch. In a static test I used almost exactly 12lb NOX from a supply tank loaned by Ivan.

No point getting a cylinder if I can't find a place to fill it.

Anyway it looks like I'm running out of time, so the launch might not happen - again. I had the same problem pre-covid and had to cancel out of URRF due to no NOX. So the motor has only been static burned once and never flown.

Apparently in this local area some years ago there was a problem with a group using a large cylinder at a party... Then all the shops started getting hit with investigations. It wasn't worth their hassle to continue. That's what I've pieced together from what I got from several sources.

Lots of the suppliers no longer supply, or will only provide the more expensive medical gas if you are a doctor with a business. They won't fill but only swap steel cylinders, and only if you have an account with them. Usually an existing account, as I found out last time around. It might be just a local problem, though we also tried in an area of NY and hit the same problems. One place up in Buffalo might refill, but it would take weeks to do so. And we only got that far due to local connections.

I'm not in shape to lug one of the large steel cylinders around!

I expect around drag strips one can get small local refills, particularly if you are known.

Gerald

 

[Dave A]

Dave, that's close to 2 hours from here in N. VA. I don't have a cylinder yet. I'd thought to get a B-50 or at least a B-35. A B-20 will only fill my motor once, and I'd planned to scale up to an EX N for next year which a B-20 wouldn't fill at all. Admittedly, a full B-20 would handle this M motor for this launch. In a static test I used almost exactly 12lb NOX from a supply tank loaned by Ivan.

No point getting a cylinder if I can't find a place to fill it.

Anyway it looks like I'm running out of time, so the launch might not happen - again. I had the same problem pre-covid and had to cancel out of URRF due to no NOX. So the motor has only been static burned once and never flown.

Apparently in this local area some years ago there was a problem with a group using a large cylinder at a party... Then all the shops started getting hit with investigations. It wasn't worth their hassle to continue. That's what I've pieced together from what I got from several sources.

Lots of the suppliers no longer supply, or will only provide the more expensive medical gas if you are a doctor with a business. They won't fill but only swap steel cylinders, and only if you have an account with them. Usually an existing account, as I found out last time around. It might be just a local problem, though we also tried in an area of NY and hit the same problems. One place up in Buffalo might refill, but it would take weeks to do so. And we only got that far due to local connections.

I'm not in shape to lug one of the large steel cylinders around!

I expect around drag strips one can get small local refills, particularly if you are known.

Gerald

All the vendors that fill at races all have tall cylinders that they swap out for another. All of ours is non-medical grade, should have a slight trace of sulfur in it.
Have you tried Norton, AirAsia or Robert's oxygen?
Some of them sell so little of it a counter salesman might blow you off thinking you want to have a party!

 

[G_T]

Robert's at least won't. Tried a couple of them, by phone and in person.

I'm not looking for medical grade. But that's all the Roberts around here will do, provided you are an MD etc.

I'm not sure who Norton is? Or AirAsia other than an airline company overseas?

 

[Dave A]

I've reached out to my racing distributor to see where he gets his non-medical grade, more to follow.

 

[G_T]

Thanks Dave!

Too many hours googling... I found 5 places that were reputed to still sell to the racing crowd within an hour of here, a few years back. I'll be checking them out tomorrow. Hopefully at least one of them is still supplying. I expect I'll have to get hold of a 20# tank ASAP! Most of what I saw of tanks for sale were expected shipping a bit late to make it all work out.

Otherwise, the rocket is coming along ok. Shoe-horning a Featherweight tracker, Peregrine, a couple boards with batteries and a TD-2 with a dbag into a 3" nosecone with extended shoulder...

 

[Troy3003]

Is there a Holston or Matheson around you? I believe both have non-medical grade and they sell to the public.

 

[rocket_troy]

FWIW I remember when I started needing N2O, we had a similar situation, but it was more an issue with cars ie. people modifying their *street* cars with N2O boost and doing stupid stuff on the streets. There was a big clampdown on distributing it after 1 or 2 nasty incidents, requiring a licence or permit to obtain it.
In my efforts to sort out a supply, I finished up contacting the state manager of the gas company supplying it. He asked me what I was using it for, which I replied “using it for rockets”. He was immediately very helpful and offered me the choice of the 3 available grades (medical, engine boost and another grade which I can’t recall – it was 25 years ago). Never had a problem with supply since.

TP

 

[Troy3003]

FWIW I remember when I started needing N2O, we had a similar situation, but it was more an issue with cars ie. people modifying their *street* cars with N2O boost and doing stupid stuff on the streets. There was a big clampdown on distributing it after 1 or 2 nasty incidents, requiring a licence or permit to obtain it.
In my efforts to sort out a supply, I finished up contacting the state manager of the gas company supplying it. He asked me what I was using it for, which I replied “using it for rockets”. He was immediately very helpful and offered me the choice of the 3 available grades (medical, engine boost and another grade which I can’t recall – it was 25 years ago). Never had a problem with supply since.

TP

I believe the medical grade now requires medical credentials. Some Universities can still get it (medical) for their programs from what I've heard.

 

[G_T]

Found the local guy who supplied nitrous for rocket people. He's out right now but expecting/hoping for more by the end of the week. Apparently lots of people looking right now...

He can only handle 20# bottle at most, and usually only does 15# and smaller. It seems bottles might be hard to get in a hurry at the moment... He's looking for me. When I was looking, what I was finding was going to take a month to ship. Clearly that won't work! I haven't made an exhaustive search yet.

 

[G_T]

I got in touch with Ivan. He's going to loan me his 20# tank. Since it looks like I can probably get that filled, I may be ok for URRF. Assuming my GSE works! It's been boxed for a few years!

Thank you everyone!

 

[Troy3003]

This is old but it may have some still in the business.https://www.holley.com/nos_refill_locations/

 

[G_T]

Thanks Troy and everyone. I'll be checking in for more places to get a refill, but at least it looks like I might now have some breathing room. That Holley link is a good one. I'll be checking out the places it indicates within perhaps an hour of here.

 

[DRAGON64]

One option that was presented to me by a local N2O supplier, was to rent a K-cylinder (yearly). When the tank emptied up, I could turn it in, and get a full one, and just pay for the N2O, and I would off again.

 

[ContrailRockets]

I only use steel cylinders to fill my aluminum cylinders. I get my NOS from local Linde supplier. Additionally when they are out it is about 60 miles away to the next Linde supplier and in a pinch I can go to Henderson. Having an account I can pick up and empty and only pay for the rental for the time I have the cylinders.
Steel weigh 118 plus 56 pounds of NOS and Aluminum weigh 51 plus 50 pounds of NOS.+

 

[G_T]

I know you sell B50 cylinders on your site, though they are hard to find. Do you also sell B35 and/or B20 cylinders?

I have sort of a retainer / vent bay in the rocket I'm constructing for URRF (thread to follow soon; I promise!). It is constructed of fiberglass and plywood. There is a brass vent line that directs potential liquid nitrous out the side, but it isn't going to do a perfect job. Given the schedule I don't have time to replace the plywood with aluminum. Are there some finishes that have better compatibility with potential nitrous exposure than others? I'm presuming oil based finishes are out. I know nitrous is a solvent and can be sensitized by organics.

Thanks,
Gerald

PS - Ok, I started the thread on the rocket: https://www.rocketryforum.com/threads/thrp-1.172951/

 

[ContrailRockets]

I know you sell B50 cylinders on your site, though they are hard to find. Do you also sell B35 and/or B20 cylinders?

I have sort of a retainer / vent bay in the rocket I'm constructing for URRF (thread to follow soon; I promise!). It is constructed of fiberglass and plywood. There is a brass vent line that directs potential liquid nitrous out the side, but it isn't going to do a perfect job. Given the schedule I don't have time to replace the plywood with aluminum. Are there some finishes that have better compatibility with potential nitrous exposure than others? I'm presuming oil based finishes are out. I know nitrous is a solvent and can be sensitized by organics.

Thanks,
Gerald

PS - Ok, I started the thread on the rocket: https://www.rocketryforum.com/threads/thrp-1.172951/

Can get 50 and 20 pound I set them with high flow 90 degree CGA 660 valves. I have not tried to get 35 pound but if its made I can get it.

 

[G_T]

I'll be figuring out what I want to do at URRF when I fly the M motor I made. At this point I'm in scramble mode trying to get ready. But afterwards I'll probably be looking to get a tank.

I broke out the GSE that I picked up several years back from someone who was getting out of hybrids. I've never used it. The tank I borrowed is basically empty. I don't know if there is any pressure remaining in it or not. I'm hoping there is enough to test the solinoid valves. I'm hoping I don't have to replace parts in a hurry.

Buried in with the stuff I found a complete Alpha Hybrids motor and about a half dozen reloads (I-250 IIRC). I had totally forgotten I had that! I do have a manual fill valve setup that could be used with it. I picked it up from Dragon64. Too bad I don't have a suitably sized rocket on hand. There should be enough nitrous in the tank I'm taking - assuming I can get it filled - to handle some flights of those little motors. Perhaps I'll bring that stuff along to URRF, and give someone's flight a free boost on Saturday. I hope to fly my project Friday morning, then chill out after our group recovers all our birds.

Gerald

PS - I like your tank collection!

 

[G_T]

Turns out I have about 10 Alpha reloads. They have different bar codes on the fuel liners. Going by memory, those don't mean anything, but were just something on the tubes being used as liners? Or were there different grain types?

Gerald

 

[G_T]

Finally I found someone with Nitrous in stock who will refill a tank. But it is going to cost me $8.50/lb. That will do for this launch but I'm hoping to find a much cheaper supplier in the future!

Gerald

 

[G_T]

I had a solinoid valve overheat problem with my GSE, so ended up borrowing Ivan's. Lots of rocket details here: https://www.rocketryforum.com/threads/thrp-1.172951/ but very short version, it flew on Friday at URRF, and was successfully recovered.

 

[Voyager1]

I had a solinoid valve overheat problem with my GSE, so ended up borrowing Ivan's. Lots of rocket details here: https://www.rocketryforum.com/threads/thrp-1.172951/ but very short version, it flew on Friday at URRF, and was successfully recovered.

I assume that was the fill solenoid? You could try a solenoid saver to reduce the HOLD current after it activates to lower the power dissipation. That should prevent over-heating.

 

[OzHybrid]

I assume that was the fill solenoid? You could try a solenoid saver to reduce the HOLD current after it activates to lower the power dissipation. That should prevent over-heating.

Solenoid saver info here.
https://www.rocketryforum.com/threads/thrp-1.172951/post-2292108

 

[G_T]

Really the solinoid is too small for filling M class and larger hybrids. Yes, a solinoid saver circuit would help. But it still doesn't have the duty cycle required for fill. I'll be doing something about it next month most likely.

 

[G_T]

THRP-1 flying at URRF on Friday. See the thread for lots more pics.

 

[OzHybrid]

THRP-1 flying at URRF on Friday. See the thread for lots more pics.

Any video you can share?