Certifying Experimental Motors

[FredA]

You make it sound like instructions and pre-selected correct parts and packaging is a triviality.

No, don't want to imply that.
Putting together a motor and getting it certified is a big task.
Just don't want others on this thread to think they can bend the rules by duplicating other's efforts because they can buy the parts.
Sorry if I was unclear.

I like what RCS sells outside of their grains.
Access to all the parts and chems is great for people who want to tinker.
Just don't see too many viable uses for their grains because they already build and certify most viable combinations.....not sure what the EX community gains by access to their grain sales. But that's just my opinion.

 

[dvdsnyd]

From looking at the RCS site, to me it looks like there's more to it(in a couple ways) than just buying the components.
For one, the cost is going to be greater than a standard reload. Also, the grains are not complete. They come as a stick. The purchaser would have to cut the grains to length and drill out the cores.

 

[AlexBruccoleri]

No, don't want to imply that.
Putting together a motor and getting it certified is a big task.
Just don't want others on this thread to think they can bend the rules by duplicating other's efforts because they can buy the parts.
Sorry if I was unclear.

I like what RCS sells outside of their grains.
Access to all the parts and chems is great for people who want to tinker.
Just don't see too many viable uses for their grains because they already build and certify most viable combinations.....not sure what the EX community gains by access to their grain sales. But that's just my opinion.

I agree they have certified a lot of the viable combinations, but there is still plenty of room to tinker safely. I am just delighted to see this since mixing propellant is not viable in my hobby life and I suspect that is the case for a lot of people. It is nice to have the option to do a little EX without going "all in".

 

[boatgeek]

From looking at the RCS site, to me it looks like there's more to it(in a couple ways) than just buying the components.
For one, the cost is going to be greater than a standard reload. Also, the grains are not complete. They come as a stick. The purchaser would have to cut the grains to length and drill out the cores.

One obvious possibility is replicating something like the CTI dual thrust (OOP) or pink motors (still in production, maybe less useful) by mixing and matching propellants. I don't think that Aerotech does the mix-and-match in their certified loads, though I could be wrong on that. Of course, making some ridiculously long 18mm motors might be fun for those interested as well.

I hadn't really realized that RCS grains were the full solid grain as opposed to being cut to length and drilled. The need to do some work on the grains themselves mostly takes away my concerns about buying the "sack of parts" motor instead of a certified motor.

 

[G_T]

Propellants are NOT generally mix and match, unless carefully designed to be so.

Gerald

 

[AlexBruccoleri]

One obvious possibility is replicating something like the CTI dual thrust (OOP) or pink motors (still in production, maybe less useful) by mixing and matching propellants. I don't think that Aerotech does the mix-and-match in their certified loads, though I could be wrong on that. Of course, making some ridiculously long 18mm motors might be fun for those interested as well.

I hadn't really realized that RCS grains were the full solid grain as opposed to being cut to length and drilled. The

I was also not aware of that. The larger grains are cored though.

 

[Rocketjunkie]

Of course, making some ridiculously long 18mm motors might be fun for those interested as well.

I have been making long 18 mm motors. The longest have 10" of propellant and are a full F These are D grain and have a 3.5 sec burn time.

 

[ksaves2]

I apologize if this question has already been asked and please link me if it has. My question. Can experimental motor enthusiast submit their motors to Tripoli for certification for non-commercial purposes? The RCS site is crazy cool and offers the opportunity to make custom motors trivially. It would be neat to make some unique motors, and then have them certified so they can be flown at non-EX launches. I suspect it is a violation of the RCS terms to sell them so this would have to stay non-commercial, though RCS might be willing to negotiate licenses if it made financial sense for all involved.

Nope,

Unless one wants to submit to the so-called governmental bodies and have NAR or Tripoli certify said given motors.

I believe that many Tripoli launches allow certified and research motor launches together as they have the appropriate launch distance intervals in place. NAR is still as I know only "paid", certified motors can be launched. PERIOD!!! Don't diddle "chit" on this point as it's fixed in stone. One can argue but I'm not going to as I'm a dual member. Go to a NAR place and I fly commercial only. Go to a Tripoli place and mix and match to one's heart content up to what the local club allows!

I wished people would give up on this, "I gotta cool motor I mixed and want to market the thing." One is not going to get rich on selling rocket stuff anyways these days.

Post the formula and have everyone else who mixes have at it if they like. Do you know how small the rocketry world is you idiots? It's quite small and get off your high horse you're going to be a millionaire 'cause ya's got's this "super cool" motor formula. All's I can say is bull sheist to you.
Post the formula on the Research pages and see what everyone else gets out of it. Maybe it can be the next "Wimpy Red" or "Brilliant Blue" formula.
Or forward it to a commercial motor maker (patent if you like beforehand) and you'll probably get back, "been there, done that and not reliable enough to market."

I've burned out 3 RCS casings with my own propellant and I didn't "beech" to them as I used their components and my OWN propellant grains. I was on my own mind you. Oh but when my own mix worked in their stuff and kicked up the rocket really nice, it was sweet pleasure. Lay off this bullsheet about marketing your own motors with your "own top secret" mix without jumping through the hoops of the legal requirements.

It's absolute stupidity. TRA and the more conservative NAR will hever allow it. TRA cause they do Research stuff with limitations on the venues they fly and NAR which is more concerned with flying certified motors. Join one or both organizations.

Trying to market a "cool" motor in this current economic environment is just plain stupid unless a company is already established and in place. Kurt Savegnago TRA 10384 NAR 11583

 

[Hobie1dog]

 

[ksaves2]

From looking at the RCS site, to me it looks like there's more to it(in a couple ways) than just buying the components.
For one, the cost is going to be greater than a standard reload. Also, the grains are not complete. They come as a stick. The purchaser would have to cut the grains to length and drill out the cores.

Yeah, If I'm going to drill out a core it's going to be one I mixed and not something commercially available.
I've flown some AT/RCS hardware with my own mixed grains. Tough to believe but I had an estimated H-160 in a two grain AT 38mm case. Flew a commercial AT H-130 in a two grain case and then right thereafter an estimated H-160 (by Burnsim) with my grains in another two grain AT case I had a J-350 nozzle that I drilled out ever so slightly as estimated. It was in two identical rocket kits I built with similar weights. My two grain, H-160ish motor kicked butt compared to the AT 130. Though I didn't have to walk as far with the H-130.
I thought that was a really nice thing my motor worked and the case stayed intact. Haven't flown in awhile but could fly this case and I expect not have problems with it. The H-130 I still like as I don't have to walk as far but my peak was a two grain 38mm flight in AT hardware that was higher impulse than the factory would supply.
That is the pleasure of flying "Ex" or Research motors that one themselves have made when they work.
The thing to remember is the RCS nozzles erode with the burn. That makes it hard to predict what is going to happen but if one is a bit aggressive, the erosion may save one from over pressurization and CATO. No way to predict that with Burnsim except if the initial burn looks aggressive with the chosen phenolic nozzle diameter, best to open it up a bit for the ground test burn. Man I learned so much by ground testing and videotaping ground burns at the highest frame speed as possible to see what was occurring.
Burnsim is geared towards non-erosive graphite nozzles so phenolic erosive nozzles are "out the door". Consider Burnsim as a non-erosive graphite nozzle predictor. Kurt Savegnago

 

[FredA]

Burnsim is geared towards non-erosive graphite nozzles so phenolic erosive nozzles are "out the door". Consider Burnsim as a non-erosive graphite nozzle predictor. Kurt Savegnago

The latest version supports nozzle erosion.
But it still takes an iteration or two to get perfected as you need to know HOW MUCH erosion will occur for a particular formula and pressure - but it DOES simulate erosion.

 

[ksaves2]

The latest version supports nozzle erosion.
But it still takes an iteration or two to get perfected as you need to know HOW MUCH erosion will occur for a particular formula and pressure - but it DOES simulate erosion.

Cool to know Fred but as you said, one needs to know how much erosion occurs. That effectively can only be had by testing. I haven't had a chance to work with the newer Burnsim but will try to get it. Sounds good.
I did have an email contact with Greg Deputy, the author of Burnsim a better part of a few years ago (maybe close to 10?) and he admitted that nozzle erosion was a very tough nut to crack. Must be some variable that can be added to the simulation though again, I think ground testing is the way to go. Would be a nice tool to play around with if you ask me. I would run a zillion runs on my two grain motor in the older version of B.S. (there I said b.s.) using different phenolic nozzle throat sizes knowing full well the program considered it a fixed nozzle throat. I'd try to hit a point where I didn't peak out the case pressure too much and then back off on the throat size just a little bit to bring the peak pressure down. What happened thereafter depended upon the mix "aggressiveness".
That worked most of the time but oh boy did it take the time, simulations and ground firings to fine tune it.
Having a close zoomed-in video camera to record at high speed helped elucidating the burn during ground tests.
I have an AT "ex" system where I use some McMaster-Carr garolite that fits as a liner in commercial AT 38mm hardware. Can generally get three flights out of the liner after using a wire brush drill bit to clean the "yutz" out. Much thicker than AT graphite composite liners but reusable. I cast in thin walled plastic casting tubes but a thick walled Garolite liner as a support to while packing the grain. Cut and core the grains and ready to fly. Yeah so since the Garolite is thicker, I have less effective space for propellant but I can use more aggressive propellant for the "loss" of propellant! Plus getting a reusable liner.

AT doesn't lose out as I use their hardware but source out the "O" rings as sometimes there are higher temp ones available on the cheap. Bought AT phenolic nozzles in bulk years ago though I'm getting a bit low now and will have to bite the bullet on the price as they're the only game in town. Am happy overall as AT had mechanical drawings posted online I could refer to so I could cut my actually "thick mother" garolite liners to size and all the specs so I could get aftermarket and sometimes higher temp rating "O" rings if I so chose to use. I could choose to spend more on high temperature "O" rings, garolite liners and clear plastic casting tubes though but in a club mixing, the motor grains were cheaper in bulk. Saved on propellant. Helped on reliability

Oh I've melted a couple of casings but have had failures with commercial stuff too. My two grain H-160"ish" in an AT case uses a nozzle from a J-350 motor. It's stupid but it works. Whoosh! and the rocket is gone. Thank heavens for GPS trackers. Kurt Savegnago