Fantasy Motors

shockie

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I just did. :) Propep says that Isp would increase...but not all that much. Theoretical Isp for BP at 250 psi is around 111 seconds. At 750 psi it's around 126 s. Assuming that the actual Isp at 250 psi is only around 80 seconds due to combustion inefficiencies, that suggests that actual Isp at 750 psi would be around 90 seconds.

I doubt that a 10-15% increase is worth the trouble of developing the technology, especially for a motor company.:(
Wouldn't operating at a higher chamber pressure, result in greater combustion efficiency? And hence,greater Isp? I think a 20% increase in BP Isp would warrant the use of CFRP casings like Aerotech uses for their Q-jets. Except dump that dang pressed clay nozzle and replace it with a screw-on nozzle.

As Ed Brown once told me, the Best BP in terms of Isp is BP that has high carbon charcoal, which depends on the wood used and how it's cooked.
Unfortunately cooking charcoal to achieve this is more an art,than a science.
By cooking I mean carbonization under heat and pressure.
 

prfesser

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Wouldn't operating at a higher chamber pressure, result in greater combustion efficiency? And hence,greater Isp? I think a 20% increase in BP Isp would warrant the use of CFRP casings like Aerotech uses for their Q-jets. Except dump that dang pressed clay nozzle and replace it with a screw-on nozzle.

As Ed Brown once told me, the Best BP in terms of Isp is BP that has high carbon charcoal, which depends on the wood used and how it's cooked.
Unfortunately cooking charcoal to achieve this is more an art,than a science.
By cooking I mean carbonization under heat and pressure.
BP would have to be a commercial variety to assure consistency. That's why Estes bought Goex. Homemade BP would be a different thing.

Higher chamber pressure does promote more-complete chemical reactions. But not all that much in a small motor. SWAG: maybe an increase in efficiency of 10%?

And if we're going with a carbon-fiber case and a machined nozzle...why bother with BP? In practical terms I'd guess that an 18x70 BP motor *might* approach full D impulse. Approach, not reach. Then again, these are fantasy motors, so anything is fair game.

I'd love to know what Firefox tried re. their purported reloadable BP motor; design and results?
 

smstachwick

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It's almost high power! ( somewhere in the K neighborhood? )
It is high-power (well over 125g propellant). But yeah, the assumed minimum of 10,000 is like a K3000. But you’d also need something like a 28-inch base to fit them all in a single-stage hexagonal cluster.
 

bjphoenix

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The major problem with BP core burners, is that they operate at higher chamber pressures. The mechical bond between the pressed clay nozzle and the paper engine casing, just isn't strong enough to contain the higher chamber pressures, resulting in the nozzle being forcibly ejected.
I'm thinking in terms of the old B.8 and B3 engines, those are the ones that I was able to buy and use. The B3 had a much larger nozzle diameter than the B.8, I assumed that allowed them to operate at similar internal pressures. If they operated at different pressures, that's information I didn't have. I've never heard of a nozzle being ejected from either a B3 or B14 motor but that doesn't mean it didn't happen.

At some point back in time I found out about FSI 21mm motors and bought some. Normal 18mm Estes motors only went to B but the 21mm FSI motor was available in C. The interesting thing to me was that both the Estes B.8 and the FSI C were end burning motors, and the flame front on the 21mm motor would be larger than on the 18mm motor, but the FSI C motor had a very small nozzle diameter so it either had a slower burning black powder or it operated at significantly higher pressure. We didn't buy a lot of those motors but we never had any problems with them.

Some years after that one of my coworkers bought some FSI F100 motors and had one complete CATO out of a package of motors.
 

dhbarr

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BP would have to be a commercial variety to assure consistency. That's why Estes bought Goex. Homemade BP would be a different thing.

Higher chamber pressure does promote more-complete chemical reactions. But not all that much in a small motor. SWAG: maybe an increase in efficiency of 10%?

And if we're going with a carbon-fiber case and a machined nozzle...why bother with BP? In practical terms I'd guess that an 18x70 BP motor *might* approach full D impulse. Approach, not reach. Then again, these are fantasy motors, so anything is fair game.

I'd love to know what Firefox tried re. their purported reloadable BP motor; design and results?
As long as we're doing graphite epoxy, I'll take some dinitramide with my perchlorate, thx
 

prfesser

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The major problem with BP core burners, is that they operate at higher chamber pressures. The mechical bond between the pressed clay nozzle and the paper engine casing, just isn't strong enough to contain the higher chamber pressures, resulting in the nozzle being forcibly ejected.
There's no reason for BP core burners to require higher pressures. In fact, since the nozzle throat is much larger than that of a comparable endburner, a coreburner can operate at relatively low pressure compared to an endburner.

For example, consider an 18x70 mm coreburning BP motor with a (typical) 1/4" dia nozzle throat, operating at 100 psi. Area of the throat = pi*r^2 = 3.14 *(0.125^2) = 0.049 sq inches. Multiply by 100 lb/sq.in. to give 4.9 lb thrust. Of course that would be the peak thrust; average would be roughly half that. Still, that's something like a B10 (or C10, depending on how much BP is in there).

An endburner with a 0.1" diameter throat operating at 100 psi would produce only about 0.8 lb or 3.5 N thrust.

One real issue with commercial production: pressing propellant into an endburner requires only a single tamp. For a coreburner, several tamps must be used, with holes of different sizes to match the tapered core as each portion of BP is added.
 

jqavins

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One real issue with commercial production: pressing propellant into an endburner requires only a single tamp. For a coreburner, several tamps must be used, with holes of different sizes to match the tapered core as each portion of BP is added.
Which is why, it seems to me, high thrust 18 mm core burners would be better done with composite, where the mandrill for the core can simply be part of the mold that the propellant is cast in. What am I missing? Why hasn't Quest/Aerotech done this with Q-jets (which are core burners to start with).
 

rharshberger

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Which is why, it seems to me, high thrust 18 mm core burners would be better done with composite, where the mandrill for the core can simply be part of the mold that the propellant is cast in. What am I missing? Why hasn't Quest/Aerotech done this with Q-jets (which are core burners to start with).
They are, look at the Enerjet line of motors
 

jqavins

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Huh? The Enerjet line has no impulse lower than E. My post posted fantasy is high thrust A and B engines, such as a genuine A10 and a B12 for example.
 

High Desert Rocketry

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Maybe a use case for laser ignition? Build a launch pad with a high power laser built into the blast deflector that's carefully aligned with the nozzle, and light the propellant that way.

We never thought of that. We have tried one of those high-power lasers that you see advertised that can start things on fire but we tried from 50 feet away hitting a mirror on the blast deflector that would redirect up the nozzle. Extremely difficult to align the laser to do that.
 

High Desert Rocketry

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Is it? My understanding is that the only required involvement by NAR/Tripoli would be a L1 to purchase.

Obviously you still need property owner approval to fly, fire marshal approval in CA, and checking with the FAA is always a good idea if not required outright, but I’ve never seen anything specifying that the launch of these motors must be at a NAR/Tripoli event. FAR is not a section/prefecture of either, for example.

To be able to test/fly things that other places cannot (especially in California) FAR bought the land and jumped through all the regulatory hoops, licenses, permits, fees, etc from both local, state, and federal governments to do what we are able to do at FAR...we recently tested and flown some S-impulse motors and no propellant has been banned at FAR. Our neighbor RRS has been safely doing similar since 1943, long before FAR, TRA, or NAR came into existence. Essentially, you play by the rules, safety codes, etc of the governing body and if a change is desired, you work for that change if it is important to you. A long-time rocket friend has this saying that advancement and change only happens by unreasonable people wanting something different.
 
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High Desert Rocketry

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OK, I know "What new motors would you like to see?" threads have been done. This time I'm asking for really out-there fantasy motors.
  • A no thrust (or trivial thrust) all tracking smoke "motor" for effects. Maybe even with colored smoke options.
  • A whole new motor size intermediate between Micro Maxx and 13×45 mm, so maybe 10×35 mm. A quick, crude calculation suggests 1/2A BP motors could be made at that size.
  • Composite, sugar, or some other stronger-than-BP propellant in the 13×45 and smaller form factors, so all of those can go up a letter. (Maybe the propellant that Klima uses; if no one will import their engines then maybe someone could license their formula. But now I'm getting dangerously close to something practical.)

Years ago someone that flys RC gliders asked me if I could make long burning sugar motors for his glider to boost them to a high altitude for flying. As an end burner, sugar isn't able to launch a rocket but can provide a small amount of thrust for a glider and offer good tracking smoke. I made some 60+ second KNSB 'sugar' endburners for him in thick cardboard tubing. worked ok until one of the tubes kept burning after the propellant was used up.

We recently used one to light a campfire for some college students at FAR when I saw the smallest log they had brought was over 2" in diameter. The long end burning sugar motor worked great to start the fire. Believe it or not, sugar propellant does have a lavender colored flame except it is hard to see in the day time because of all the white smoke and I've made a few with Mach Diamonds..
1669653445072.png
 

High Desert Rocketry

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I'm not a big fan of color propellant but I occasionally help put on July 4th firework celebrations for cities here in California. While doing that I thought it would be cool to have a motor burn red, white, and then blue...perhaps Redline first, then White Lightning, then Blue Thunder. It might be easy to construct with a 3 grain end burner but for more thrust using cored BATES grains. each grain would need to be formed to burn those colors as the web burned away.
I suggested it to Aerotech and CTI but neither seemed interested nor did my friends that usually make AP. Then Derek stepped up to the plate and offered to make one that we tested a few years ago at FAR. I think he has also made some red and green ones for Christmas time.
A downside is that the rocket will be flying away into the sky as the colors change and probably not be very visible unless used in a large motor.

 
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boatgeek

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I'm not a big fan of color propellant but I occasionally help put on July 4th firework celebrations for cities here in California. While doing that I thought it would be cool to have a motor burn red, white, and then blue...perhaps Redline first, then White Lightning, then Blue Thunder. It might be easy to construct with a 3 grain end burner but for more thrust using cored BATES grains. each grain would need to be formed to burn those colors as the web burned away.
I suggested it to Aerotech and CTI but neither seemed interested nor did my friends that usually make AP. Then Derek stepped up to the plate and offered to make one that we tested a few years ago at FAR. I think he has also made some red and green ones for Christmas time.


That's pretty cool. Did you inhibit the ends of the grains to keep the colors from leaking into each other?
 

jqavins

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[W]e recently tested and flown some S-impulse motors...
😲

Believe it or not, sugar propellant does have a lavender colored flame except it is hard to see in the day time...
Of course it does; that's the potassium. And you can see it in daylight in some formulations better than others. I've burned some stoichiometric KN-Vaseline (don't ask) and the color was easily evident (due to there being virtually no smoke).
 
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jqavins

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It was an experiment meant to, I hoped, lead to a propellant. One that would not include Vasoline; that was a stand-in for wax that I didn't know how to handle for good blending, and sufficient for a very small test to see if I was on the trail of anything remotely worthwhile. Anything more that that I shouldn't post outside of the restricted propulsion forum (even though it's most likely useless).
 

High Desert Rocketry

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One of my 'fantasy' motors is the sugar ZnS combo.
Inexpensive Sugar motors have lots of tracking smoke but no flame



and zinc sulfur rockets have such an awesome flame at liftoff



I tried once to have a motor with a ZnS-filled core for flame with sugar surrounding it to provide the white tracking smoke transition from the black ZnS smoke but it didn't work out...I think the fast burning ZnS core fractured the surrounding sugar propellant causing it to CATO. It would have had 100% volumetric propellant loading in the motor.

 

Neutronium95

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I'm not personally interested in ever working with ZnS motors, due to the safety issues and low overall performance.


I would love to see someone come up with an APCP recipe that could produce similar results. I've never seen anything quite like a ZnS motor. Crazy high acceleration, and an absolutely insane trail of fire and smoke. I'm pretty sure that the absurd amount of fire is because of propellant coming out of the nozzle befor fully burning, so replicating it might be difficult to near impossible.

launch-zinc-sulfur-rocket-9869770.jpg
 

High Desert Rocketry

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😲


Of course it does; that's the potassium. And you can see it in daylight in some formulations better than others. I've burned some stoichiometric KN-Vaseline (don't ask) and the color was easily evident (due to there being virtually no smoke).
Yes, I should have said you get lavendar with KNO3 sugar, yellow with NaNO3, red, with SrNO3 sugar, etc.
 

High Desert Rocketry

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I'm not personally interested in ever working with ZnS motors, due to the safety issues and low overall performance.


I would love to see someone come up with an APCP recipe that could produce similar results. I've never seen anything quite like a ZnS motor. Crazy high acceleration, and an absolutely insane trail of fire and smoke. I'm pretty sure that the absurd amount of fire is because of propellant coming out of the nozzle befor fully burning, so replicating it might be difficult to near impossible.

launch-zinc-sulfur-rocket-9869770.jpg
I'm always amazed when people talk about not using a particular rocket formula because of a safety issue. Every rocket propellant needs to be treated with respect. Some people think 'sugar' propellants are dangerous and blow up but I can make hundreds of them in many different sizes (A-S impulse) and not CATO a single one. Some people say nitrous or LOX or...are dangerous but I've worked with many and you simply have to know how to treat each one. On the facebook CATO Club group, most motors are either BP or APCP.

As for performance, when students I work with mention they need something with 'more performance', I ask them what size payload are they putting into orbit. Probably impossible with ZnS or black powder, really hard to do with sugar, not often done with APCP, and most often with liquid bi-propellant so if you're looking for performance, liquid or ion or nuclear would be the choice.

Sparkies could be considered similar to ZnS motors with long firery tails streaming out of the nozzle. A couple of times I've loaded the core of a motor with ap leftovers and watched them come flaming out...not recommended
 
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jqavins

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A slightly fuel rich propellant with a sodium bearing fuel might do the trick for the firey display. A sodium soap or other organo-sodium salt might do the trick. Horribly low ISP probably, unless the fuel salt is a small fraction among some "normal" better fuel.
 

MarsFire

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Motors with a rich purple flame. Not an odd shade of pink but actually purple.
Motors with dense bright green smoke.
Dark Star motors brought back.
Silver Streak motors brought back.
The Estes B8-5 brought back.

1980s pricing brought back.

You said fantasy right?

Andrew
 

prfesser

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Actually there's no reason (other than financial) that Silver Streaks couldn't be brought back. The issue is that any motor containing over 62.5 g of BP requires a BATFE license (used to be a LEUP) to purchase and use. I know, it makes so much sense when one considers the amount of BP that can be purchased and stored without any permit or license...
 

Initiator001

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Which is why, it seems to me, high thrust 18 mm core burners would be better done with composite, where the mandrill for the core can simply be part of the mold that the propellant is cast in. What am I missing? Why hasn't Quest/Aerotech done this with Q-jets (which are core burners to start with).
The Quest Q-Jet motors use C-Slot propellant grains. To make a true coreburner grain would take more labor and time. Each propellant grain is not individually molded. Beyond that I can't say any more.
 

shockie

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I'm not personally interested in ever working with ZnS motors, due to the safety issues and low overall performance.


I would love to see someone come up with an APCP recipe that could produce similar results. I've never seen anything quite like a ZnS motor. Crazy high acceleration, and an absolutely insane trail of fire and smoke. I'm pretty sure that the absurd amount of fire is because of propellant coming out of the nozzle befor fully burning, so replicating it might be difficult to near impossible.

launch-zinc-sulfur-rocket-9869770.jpg
Oh yeah!
 
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