Supersonic on blackpowder?

I was thinking about this last night, maybe it was the fumes from the glue and paint,
or maybe the single malt scotch. Has anyone every gone supersonic on BP motors?
I can think of a bunch of reasons why it would not work. Exhaust gas velocity too low,
etc. Just curious...

Hmmm, I think I need more scotch tonight!

More scotch indeed.

The exhaust velocity is low compared to AP composite propellants, but it is way above the speed of sound in air. Taking the specific impulse to be about 80 sec and multiplying by 32 gives and exhaust velocity of about 2,400 fps. A BP rocket then needs a mass ratio sufficient to get up to about 1100 fps. If the mass ratio of commercial motors is low, there is the option of doing multi-staging. Someone needs to sit down and crank out the numbers to see if this is possible.

Already done! :wink:

IF (and that's a big if) you can find an FSI F100-0 and D20-8 they claimed in the right rocket that it would go supersonic. I believe the rocket was called a Dart or something like that if I remember it right.


edit: Ahhh, I was right. Memory still works if nothing else


https://www.ninfinger.org/rockets/catalogs/fsi90/90fsi8.html

Dave, thanks for the information, found some more links.

https://www.rocketryforum.com/showthread.php?10534-FSI-******-Dart-clone

https://www.oldrocketplans.com/fsi/fsiMRK-XVII/fsiMRK-XVII.htm

https://www.rocketryforum.com/showthread.php?5953-Supersonic-MODEL-Rocket/page2

I know they launch GIANT black powder rockets in Thailand, I doubt those ever go supersonic.

dave carver said:

IF (and that's a big if) you can find an FSI F100-0 and D20-8 they claimed in the right rocket that it would go supersonic. I believe the rocket was called a Dart or something like that if I remember it right.


edit: Ahhh, I was right. Memory still works if nothing else


https://www.ninfinger.org/rockets/catalogs/fsi90/90fsi8.html

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I had the Dart when I was a kid. It blew up about 10ft off the pad.

qquake2k said:

I had the Dart when I was a kid. It blew up about 10ft off the pad.

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Yeah, the F100 was like a 50-50 chance of blowing up...at least the ones I got Blew up a FSI Black Brant on it's first flight, still have the chute. I cloned it with some SEMROC parts and a sandman cone. The ejection charge of a H128 cut the shock cord when it got caught under the wadding but it was recovered and a good thing it was, cone cost me 40 bucks

I had one that worked but did not know if it went supersonic as according to the instructions you had to be at least a couple hundred feet from the launch pad to hear the sonic boom.

Ruggieri makes (made?) a large "J" class black powder motor for a cloud seeding rockets. French schools and universities would launch their rockets using this motor. The motor was known as "Bambi". https://adloff-dreyer.fr/gretss/english/prop.html#bambi. About 700 gram (1.5 lbs) of black powder, if I recall correctly. With a light rocket you may be able to hit supersonic, but I havn't done the sim.

Jeroen_at_CTI said:

Ruggieri makes (made?) a large "J" class black powder motor for a cloud seeding rockets. French schools and universities would launch their rockets using this motor. The motor was known as "Bambi". https://adloff-dreyer.fr/gretss/english/prop.html#bambi. About 700 gram (1.5 lbs) of black powder, if I recall correctly. With a light rocket you may be able to hit supersonic, but I havn't done the sim.

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Interesting find Jeroen. GRETSS claims their 104 mm 9161M3780 Caribou motor will make a larger rocket go supersonic.

Bob

bob jablonski said:

I had one that worked but did not know if it went supersonic as according to the instructions you had to be at least a couple hundred feet from the launch pad to hear the sonic boom.

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If a rocket was supersonic AT the launch pad, you might hear a boom if you were off to the side. If the rocket was big enough. And if it had the "right" shape to generate a strong shock wave. And if you are close enough. And if the weather conditions were good.

If a rocket is at zero velocity at the pad and is still subsonic while it is climbing and accelerating to supersonic speed, you are not going to hear a shock wave if you are on the ground, off to the side. Even assuming that the rocket has such tremendous performance that it is fully supersonic within 100 feet, you are not going to hear a shock wave. The compression and expansion waves created by a supersonic body propagate forward....which for a vertical ascent means the shock waves would move upward. You would have to be off to the side and up in the air several thousand feet to hear any sonic boom. It's basic physics.

powderburner said:

If a rocket was supersonic AT the launch pad, you might hear a boom if you were off to the side. If the rocket was big enough. And if it had the "right" shape to generate a strong shock wave. And if you are close enough. And if the weather conditions were good.

If a rocket is at zero velocity at the pad and is still subsonic while it is climbing and accelerating to supersonic speed, you are not going to hear a shock wave if you are on the ground, off to the side. Even assuming that the rocket has such tremendous performance that it is fully supersonic within 100 feet, you are not going to hear a shock wave. The compression and expansion waves created by a supersonic body propagate forward....which for a vertical ascent means the shock waves would move upward. You would have to be off to the side and up in the air several thousand feet to hear any sonic boom. It's basic physics.

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Say it ain't so! It is so cool to hear the motors go boom boom and shout "That baby just went supersonic!" Then everyone can do big jump high fives! Say it ain't so!

bobkrech said:

Interesting find Jeroen. GRETSS claims their 104 mm 9161M3780 Caribou motor will make a larger rocket go supersonic.

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The Caribou was the Holy Grail for European rocket flyers. 90 mm diameter military-grade SNPE extruded double-base propellant in a spiral strip welded metal casing. Donated by the French government (CNES) to rocket teams. And you got to keep the case after the flight. Nowadays they fly Pro54 and Pro75 motors - and save a lot of money. Ignited with 1A/1W Davey Bickford initiators that probably cost more then our reloads.....

Jeroen.

powderburner said:

If a rocket was supersonic AT the launch pad, you might hear a boom if you were off to the side. If the rocket was big enough. And if it had the "right" shape to generate a strong shock wave. And if you are close enough. And if the weather conditions were good.

If a rocket is at zero velocity at the pad and is still subsonic while it is climbing and accelerating to supersonic speed, you are not going to hear a shock wave if you are on the ground, off to the side. Even assuming that the rocket has such tremendous performance that it is fully supersonic within 100 feet, you are not going to hear a shock wave. The compression and expansion waves created by a supersonic body propagate forward....which for a vertical ascent means the shock waves would move upward. You would have to be off to the side and up in the air several thousand feet to hear any sonic boom. It's basic physics.

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I believe you are correct in the above. Any "popping" might be coming from the motor if there were bubbles in the grain(s). One could (illegally mind you) send a mach buster off at a 45 degree angle and perhaps might "hear" the shockwave standing downrange a bit. That of course is not adviseable.

Yeah, I was bummed out when read about this revelation in the past too but I believe it's the correct gospel. You can take solace in the fact that you might be able to "see" the transonic shockwave as the rocket enters and exits supersonic on your
baro altimeter dowload pattern. I saw it on an MAWD as a definite spike right where the simulation said it would occur and there was a smaller spike as it came subsonic about .6 sec later. Kurt

The Caribou was the Holy Grail for European rocket flyers. 90 mm diameter military-grade SNPE extruded double-base propellant in a spiral strip welded metal casing. Donated by the French government (CNES) to rocket teams. And you got to keep the case after the flight. Nowadays they fly Pro54 and Pro75 motors - and save a lot of money. Ignited with 1A/1W Davey Bickford initiators that probably cost more then our reloads.....

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If it is double-base propellant, that does not sound like black powder.

I flew an FSI Dart model during the Velocity trials held outside of Las Vegas back in 1990 or 1991.

Back then we didn't have all these fancy on-board electronic payloads to measure things. No sir!
We had to fly the rockets at night and use film cameras to photograph the flights. After the pictures were printed, we could determine the velocity of the models.

My FSI Dart reached 460 MPH on the F100-0 booster. Sadly, the D20 upper stage did not ignite so we may never know if this model could reach/exceed Mach 1.

powderburner said:

If a rocket was supersonic AT the launch pad, you might hear a boom if you were off to the side. If the rocket was big enough. And if it had the "right" shape to generate a strong shock wave. And if you are close enough. And if the weather conditions were good.

If a rocket is at zero velocity at the pad and is still subsonic while it is climbing and accelerating to supersonic speed, you are not going to hear a shock wave if you are on the ground, off to the side. Even assuming that the rocket has such tremendous performance that it is fully supersonic within 100 feet, you are not going to hear a shock wave. The compression and expansion waves created by a supersonic body propagate forward....which for a vertical ascent means the shock waves would move upward. You would have to be off to the side and up in the air several thousand feet to hear any sonic boom. It's basic physics.

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Powderburner is exactly correct:
Standing on the ground within the a couple hundred feet of the launcher No One is going to hear any booms.
Back in the 70-80's with several larger FSI BP motors many folks constructed fibreglass reinforced very light weight small models that were calculated to exceed the speed of sound. But as mentioned about no one could confirm with an audible "boom".

First Las Vegas Turkey Shoot we saw a Teeling Tech H1000 in a carbon fiber minimum diameter rocket go up. There were two distinctive noises, the boom of 360 newtons burning in .3 of a second and the distinct "pop" of the sonic "boom". It was not a motor backfire or delayed burn. As it was only 29mm in diameter you're not going to get a boom, that takes something much bigger. We were about 150 feet away and I don't think the rocket was much higher than 500 feet when it happened. The recovery failed and recovery was by shovel, it buried itself about 4" past the fins in the El Dorado playa. The rocket was dig up intact...

dave carver said:

First Las Vegas Turkey Shoot we saw a Teeling Tech H1000 in a carbon fiber minimum diameter rocket go up. There were two distinctive noises, the boom of 360 newtons burning in .3 of a second and the distinct "pop" of the sonic "boom". It was not a motor backfire or delayed burn. As it was only 29mm in diameter you're not going to get a boom, that takes something much bigger. We were about 150 feet away and I don't think the rocket was much higher than 500 feet when it happened. The recovery failed and recovery was by shovel, it buried itself about 4" past the fins in the El Dorado playa. The rocket was dig up intact...

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Whew! Thanks for saving the model rocketry fun! For awhile there I thought the hard science was going to make all our dreams of model rocket sonic booms impossible. Just need to have the guts to use that old F100 and I am now again sure of black powder supersonic flight. Blast past the speed of balsa and right into whoosh pop wonderland. Talk the talk of supersonic flight and fin flutter with the high power boys. It will be awesome. like Disneyland, where all your dreams come true.

Just don't mindsim your black powder supersonic flight, the "pop" you will hear might just be the stroke that brings on the Grim Reaper. Way too dangerous to mindsim stuff like that.

Someday I really hope to hear that lovely black powder sonic boom. Too bad supersonic flights were banned after the big Oklahoma City lawsuit. The public would not buy "The Sound of Freedom" campaign and would get all mad, even at a minor SR 71 mishap now and then. Speed limits for Concord and bye bye to the SST program, a historic black eye for the FAA. Public outcry really cracked the whip on public officials. Hopefully hard rocket science and the RSO won't crack the whip on my black powder sonic boom dreams, but if I show up with an old F100 I know the rod will not be spared. After that kind of rejection the only thing to do will be to lock myself in the pickup cab and crank up Aerosmith's "Dream On.":headbang:

I still have a shred of hope that we will see .new' F100's. It is not more than a glimmer deep down, but it is there.

rstaff3 said:

I still have a shred of hope that we will see .new' F100's. It is not more than a glimmer deep down, but it is there.

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I try to wear the new FSI Tee Shirt to the launch at least once a month. It gives all the Old Farts hope they can once again return to those glory days. Who needs the little blue pill when you have an F100 in your hand? That is why I gave the Pad Fuehrer that old box of FSI Motors to safely store at his house. Everything I read on the forums gives me hope, and as long as there is hope I guess you are OK. Damned the torpedoes and full speed ahead, high speed black powder motors will rise again! One thing is for sure, they will either go boom on the pad or in the air. Whatever the outcome it will not disappoint, just like the good old days.

[video=youtube;YezcI-cmOUg]https://www.youtube.com/watch?v=YezcI-cmOUg[/video]

now that's a black powder rocket!

Daddyisabar said:

I try to wear the new FSI Tee Shirt to the launch at least once a month. It gives all the Old Farts hope they can once again return to those glory days. Who needs the little blue pill when you have an F100 in your hand? That is why I gave the Pad Fuehrer that old box of FSI Motors to safely store at his house. Everything I read on the forums gives me hope, and as long as there is hope I guess you are OK. Damned the torpedoes and full speed ahead, high speed black powder motors will rise again! One thing is for sure, they will either go boom on the pad or in the air. Whatever the outcome it will not disappoint, just like the good old days.

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I still have a old FSI sticker on my range box and a couple original kits and Semroc clones. Roomer has it some new kits will be out soon. I have a order just waiting to be filled (told within a couple weeks). With any luck motors may show up in a year or 2. Not a cheap thing to do with all the regulations and insurance. I wonder if Vern could have brought the motors to market nowadays? You can't make a machine start making motors and sell them without government approval and all the red tape nowadays. Unless you have the time and GOOD financial backing. I know the time and cost from when I looked into making motors for Starlight Rockets.

taiwanluthiers said:

[video=youtube;YezcI-cmOUg]https://www.youtube.com/watch?v=YezcI-cmOUg[/video]

now that's a black powder rocket!

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This is the rocket festival - Boon Bung Fai in North Eastern Thailand. Been their to see the festival myself. Every year you have a fatality due to explosive CATOs. Many of these rockets travel 8 to 10 km from the firing pad. I think the record is 15 km...

These are made from an ancient BP recipe that locals know about. I've seen them manufacturing the propellent as well.

Anybody want to try it again?

There was an article in the 1980s in the "Model Rocketeer" about going supersonic in model rocketry. They mentioned 3 ways to verify the deed. One was by photography, like Bob mentioned. The second way was with a special type of paint that would change color at a certain temperature, taking advantage of the fact that the tip of the nose cone and leading edges of a rocket would reach a certain temperature because of heating by aerodynamic friction. The 3rd way to tell was by launching a rocket at a very low degree angle from the ground and having someone several hundred feet away down-range to hear the sonic boom (more like sonic crack). This 3rd way was STRONGLY discouraged because, it went against the rocket safety code.
I can't recall if it was in this same article, but it stated that the FSI Dart system, didn't have enough trust to break the sound barrier.

Anybody recall the article in question? Anybody know what the name of the temperature color changing paint was called? I don't recall the name of it.

I flew the FSI combo back in the day...meh.

I do (just intuitively) think that maybe a two stage RocketFlite H220-0 staged to a H220-8 might do the trick. Those motors packed a wallop.

I believe you may hear the sonic "pop" if the rocket goes SS quick enough and your range has a mountain or large hill on one side. I think I've read this as well as saw a video where the poster noted it could be heard.