Bi-liquid fueled model rocket?

[Jaker48895]

I have been skeeming the possibility of a hydrocarbon and oxygen fueled rocket and started to wonder if it is actually possible on a relatively small scale. Have you guys ever heard of one? I would love the input!

 

[shreadvector]

A "Model Rocket" has a specific legal and technical definition. What you have described is an "Amatuer Rocket". The moderators will probably direct you to read the rules for this forum.

 

[rocket999]

I have been skeeming the possibility of a hydrocarbon and oxygen fueled rocket and started to wonder if it is actually possible on a relatively small scale. Have you guys ever heard of one? I would love the input!

Discussing experimental rocket motors in detail is not allowed on this forum. Take a look at this link.

https://www.rattworks.net/research_tribrid.html

You need to be a TRA member and L2 to fly it at experimental launches. If you ask this over at the rocketry planet forum people can explain this subject in more detail then is allowed here.

Sam

 

[bobkrech]

I have been skeeming the possibility of a hydrocarbon and oxygen fueled rocket and started to wonder if it is actually possible on a relatively small scale. Have you guys ever heard of one? I would love the input!

"Model rocket" is a legal description of a hobby rocket weighing not more than 1500 grams and powered by commercially manufactured and certified solid rocket motors only. Model rocketry is legal in all states, does not require FAA permission, and very safe.

A rocket with a biprop liquid motors would be legally classified as an amateur rocket. Amateur rockets do not use commercially available motors, require FAA and other permits, is not legal in many places, and can be risky, or in the case of cryogenic biprop liquids, dangerous even if you have an engineering degree and know what you're doing. If you don't know the answer to your own question, you are not qualified to delve into amateur rocketry.

TRF is a discussion group of folks who have a common interest in hobby rocketry. Many of us are also aerospace professionals in our day jobs, but the discussions here are limited to model and high power rocketry using commercial certified hobby rocket motors. We welcome you to participate and learn with us at TRF but please read our rules.

Bob Krech
TRF High Power and Propulsion Moderator

 

[powderburner]

I have been skeeming the possibility of a hydrocarbon and oxygen fueled rocket and started to wonder if it is actually possible on a relatively small scale. Have you guys ever heard of one? I would love the input!

Yes, I have heard of them. No, they are not the same thing as a big rocket scaled down. Without going into details, it is usually the case that something like a pump that pushes 100 gallons per minute and weighs 100 pounds on a NASA launch vehicle does not scale down in all respects to very small sizes; the corresponding pump for one of our projects that might only need to push 1 gallon per minute could still easily weigh 10 or 20 pounds. If you are talking about oxygen, it would have to be in liquid form to even begin to make a rocket design work, and tackling cryogenics is far more difficult than it looks like. Actually, I am not even sure that it is possible to "downscale" complex liquid systems turbo-machinery at all (and end up with reliable flight-weight hardware); most of the amateur liquid systems I have seen are simple blow-down systems pressurized by onboard gas systems. (Maybe that will sort of answer part of your question, without going into details of chemicals or rocket design.)

For small liquid propellant systems you end up using different propellants, structural materials, machinery design, system design, and everything else. Every aspect of this requires extensive expertise in many areas, or close availability of many other people who can fill in as experts. There is a reason why you don't see much of this kind of rocketry, even on the websites for experimental and amateur rocketry. It is very, very difficult to make it work; it is very easy to kill yourself in any attempt to build these things.

Since this was your first post here on TRF it might be possible to assume that you are genuinely uninformed about the complexities of liquid propulsion systems. That's completely OK, everybody was a newbie sometime. For whatever reason this idea caught your attention, by all means, study it further and learn about it all you can. It might even lead you to a degree in aerospace or mechanical engineering.

I'm really not trying to lecture, just trying to illustrate the point that these other guys have already posted: these are extremely advanced questions, and very dangerous subject material to post blindly on the internet and put into the hands of all those idiots that are loose and unsupervised out there.

What is the rest of your rocketry experience? Come on back with more questions about hobby rocketry and we will be glad to help out!

 

[mjennings]

I remember seeing an add, maybe in a high power magazine, in or about 2000, (the magazine was likely borrowed from a professor so it was probably older than 2000) for a commercially built liquid fueled motor for HPR sized birds. I think it used 30% H2O2 and diesel on a pressure fed system. Still even these fuels are dangerous. Drug store H2O2 is at 3% and is pretty safe but you start upping the concentration and it can cause serious injury.

Basically stick to the solids and hibrids, less failure modes, easier to get, you aren't making it so you don't have to worry about the machining tolerances. If you want to play with the liquids get a job at Marshal or Stennis Space Flight Centers, or one of the engine companies.

 

[daveyfire]

Pressure-fed biprops aren't really any more scary or dangerous or difficult than hybrids. They simply present a different set of challenges. I've heard the viewpoint that they are safer than solids, since you can shut them off if something goes wrong. Many popular propellants are very inexpensive and readily available, and it is certainly possible to make a flying biprop that is the size of a large model rocket.

That said, as noted by bobkrech, the topic of liquid rocket development is outside the scope of this particular rocketry forum, which is targeted towards model and high power rocketry with commercially available motors. Very few hobbyists out there are doing biprop work, but there are a few active amateur groups -- if you are interested in learning more, I highly recommend joining the RRS (https://www.rrs.org); they offer a tremendous information resource to those looking to get started in biprops. I also recommend Huzel and Huang's text on liquid propellant engines (available for free from NTRS or nicely bound and edited from AIAA), which will illustrate how complex the construction of a biprop engine really can be.

Don't be afraid to explore bipropellant engine development on a hobby scale. It's certainly possible. And you will learn a lot more than you would working for PWR.

 

[bobkrech]

I remember seeing an add, maybe in a high power magazine, in or about 2000, (the magazine was likely borrowed from a professor so it was probably older than 2000) for a commercially built liquid fueled motor for HPR sized birds. I think it used 30% H2O2 and diesel on a pressure fed system. Still even these fuels are dangerous. Drug store H2O2 is at 3% and is pretty safe but you start upping the concentration and it can cause serious injury.

Basically stick to the solids and hibrids, less failure modes, easier to get, you aren't making it so you don't have to worry about the machining tolerances. If you want to play with the liquids get a job at Marshal or Stennis Space Flight Centers, or one of the engine companies.

That was the System Solaire. I'd don't know if anyone actually got one to work. The thrust to weight was atrocious and if you look around on this and other forums, you will find unhappy folks.

Pressure-fed biprops aren't really any more scary or dangerous or difficult than hybrids. They simply present a different set of challenges. I've heard the viewpoint that they are safer than solids, since you can shut them off if something goes wrong. Many popular propellants are very inexpensive and readily available, and it is certainly possible to make a flying biprop that is the size of a large model rocket.

That said, as noted by bobkrech, the topic of liquid rocket development is outside the scope of this particular rocketry forum, which is targeted towards model and high power rocketry with commercially available motors. Very few hobbyists out there are doing biprop work, but there are a few active amateur groups -- if you are interested in learning more, I highly recommend joining the RRS (https://www.rrs.org); they offer a tremendous information resource to those looking to get started in biprops. I also recommend Huzel and Huang's text on liquid propellant engines (available for free from NTRS or nicely bound and edited from AIAA), which will illustrate how complex the construction of a biprop engine really can be.

Don't be afraid to explore bipropellant engine development on a hobby scale. It's certainly possible. And you will learn a lot more than you would working for PWR.

Dave

I'm guessing that you don't have much experience with liquids.

In the overall picture liquids, whether pressure fed or pumped are far more dangerous than either hybrids or solids. The principal problem is ignition delay. If you don't light a solid this millisecond, it may light in the next or not at all. If not, there isn't a safety issue. Hybrids are more of a concern because if the injectors are too large, you get oscillatory combustion and if you then get a back flash, you detonate the nitrous tank. Liquids are the most dangerous, because if you get a delayed ignition, the combustion chamber can explodes due to pooled premixed propellants and then the rocket soon follows.

I'm not saying that an amateur can't make one work, but I'm saying it takes a lot of reading, and engineering skills to make a liquid work properly, but even then they aren't necessarily safe. Your references are excellent. The RRS group are really semipros and they have a complete liquid launch system with block house and cryogenic propellant support, however there's big bucks invested into their test and launch facilities.

But again, not a topic for TRF.

Bob

 

[shockie]

close but no cigar:

31-1-6. DEFINITIONS

a. Amateur rocket – an unmanned rocket that is propelled by a motor or motors having a combined total impulse of 889,600 Newton-seconds (200,000 pound-seconds) or less; and cannot reach an altitude greater that 150 kilometers (93.2 statute miles above the Earth's surface.

b. Amateur Rocket classes:

1. Class 1 - a model rocket that uses no more than 125 grams (4.4 ounces) of propellant; uses a slow-burning propellant; is made of paper, wood, or breakable plastic; contains no substantial metal parts; and weighs no more than 1,500 grams (53 ounces) including the propellant.

Seems the FAA defines model rockets as Class 1 amateur rockets.

Terry Dean

 

[JAL3]

That was the System Solaire. I'd don't know if anyone actually got one to work. The thrust to weight was atrocious and if you look around on this and other forums, you will find unhappy folks.


Bob

That was the outfit I tried to order from. They took my money and sent nothing.

Last year I mentioned that experience on TRF 1 and was contacted by System Solaire and told they would sent me the goods. I ordered the instructions, not a motor. I sent them my address and I'm still waiting.

 

[shreadvector]

FAA definitions only apply if the discussion is about FLYING the rockets in the air.

The discussion is mostly about manufacturing/making the rocket, fueling the rocket, handling the chemicals, etc. This is done on the ground and FIRE Regulations apply to those activities. The definitions of the Fire Regulatory Agencies (or AHJs) apply.

Of course, you should have known that.

Just like you know that shipping and transporting involve different authorities/agencies.

close but no cigar:

31-1-6. DEFINITIONS

a. Amateur rocket – an unmanned rocket that is propelled by a motor or motors having a combined total impulse of 889,600 Newton-seconds (200,000 pound-seconds) or less; and cannot reach an altitude greater that 150 kilometers (93.2 statute miles above the Earth's surface.

b. Amateur Rocket classes:

1. Class 1 - a model rocket that uses no more than 125 grams (4.4 ounces) of propellant; uses a slow-burning propellant; is made of paper, wood, or breakable plastic; contains no substantial metal parts; and weighs no more than 1,500 grams (53 ounces) including the propellant.

Seems the FAA defines model rockets as Class 1 amateur rockets.

Terry Dean

 

[daveyfire]

Dave

I'm guessing that you don't have much experience with liquids.

Well, aside from having helped design, build, and fire several amateur and professional bipropellant pump and pressure-fed engines, no, not really :cyclops:

In the overall picture liquids, whether pressure fed or pumped are far more dangerous than either hybrids or solids. The principal problem is ignition delay. If you don't light a solid this millisecond, it may light in the next or not at all. If not, there isn't a safety issue... Liquids are the most dangerous, because if you get a delayed ignition, the combustion chamber can explodes due to pooled premixed propellants and then the rocket soon follows.

Hard starts are certainly a major problem with liquids, but one that is easily controlled with proper ignition sequencing, valve control, and purge systems. Proper propellant selection and modern computer control has simplified these issues dramatically. (This is one reason the System Solaire vehicle was such a disaster -- gasoline is a TERRIBLE choice for a liquid rocket propellant, largely because of the ignition challenges it presents.)

I'm not saying that an amateur can't make one work, but I'm saying it takes a lot of reading, and engineering skills to make a liquid work properly, but even then they aren't necessarily safe. Your references are excellent. The RRS group are really semipros and they have a complete liquid launch system with block house and cryogenic propellant support, however there's big bucks invested into their test and launch facilities.

Maybe that's why I'm biased Having worked on and fired many a liquid at the MTA, I can assure you it's not nearly as terrible as it may seem. If I can get a biprop together for a senior design project, it can't be too bad. These guys have over 5 minutes of firing on their engine and they're a couple of hobbyists working out of their garage who bring up a dewar of LOX and a barrel of fuel in their truck when they want to fire. There is no real grand cryogenic propellant support system at the MTA, just a few test stands and a blockhouse. Biprops tend to crop up out there mostly because it's where all the biprop geeks hang out already -- there's lots of people to help you along.

And that's the valuable part, just like anything else: finding people to help you learn and find your way along the path. Like I said before, biprops aren't necessarily any more difficult or dangerous than a hobby hybrid -- personally I'd rather be around 60,000 gallons of LOX than 60,000 gallons of N2O any day -- they're just dangerous in a different way. Many people seem to see the "different" dangerous as "more" dangerous -- it's not, it just presents a different set of challenges to be aware of. And though TRF is certainly not the proper forum for the discussion of the design, build, and testing of a biprop engine, I think we can be a little more supportive and point out the proper place to discuss, rather than simply stating "biprops are dangerous, don't do them."

 

[RocketFeller]

I remember seeing an add, maybe in a high power magazine, in or about 2000, (the magazine was likely borrowed from a professor so it was probably older than 2000) for a commercially built liquid fueled motor for HPR sized birds. I think it used 30% H2O2 and diesel on a pressure fed system. Still even these fuels are dangerous. Drug store H2O2 is at 3% and is pretty safe but you start upping the concentration and it can cause serious injury.

Basically stick to the solids and hibrids, less failure modes, easier to get, you aren't making it so you don't have to worry about the machining tolerances. If you want to play with the liquids get a job at Marshal or Stennis Space Flight Centers, or one of the engine companies.

I sent off a money order for $16.95 (I think...) back around that time for the "System Solaire" plans, mostly out of curiosity. I never received the plans and was unable to get any response as to why not.

 

[RocketFeller]

That was the outfit I tried to order from. They took my money and sent nothing.

Last year I mentioned that experience on TRF 1 and was contacted by System Solaire and told they would sent me the goods. I ordered the instructions, not a motor. I sent them my address and I'm still waiting.

I missed this post - sounds like a common problem...

 

[bobkrech]

Well, aside from having helped design, build, and fire several amateur and professional bipropellant pump and pressure-fed engines, no, not really :cyclops:

Hard starts are certainly a major problem with liquids, but one that is easily controlled with proper ignition sequencing, valve control, and purge systems. Proper propellant selection and modern computer control has simplified these issues dramatically. (This is one reason the System Solaire vehicle was such a disaster -- gasoline is a TERRIBLE choice for a liquid rocket propellant, largely because of the ignition challenges it presents.)

Maybe that's why I'm biased Having worked on and fired many a liquid at the MTA, I can assure you it's not nearly as terrible as it may seem. If I can get a biprop together for a senior design project, it can't be too bad. These guys have over 5 minutes of firing on their engine and they're a couple of hobbyists working out of their garage who bring up a dewar of LOX and a barrel of fuel in their truck when they want to fire. There is no real grand cryogenic propellant support system at the MTA, just a few test stands and a blockhouse. Biprops tend to crop up out there mostly because it's where all the biprop geeks hang out already -- there's lots of people to help you along.

And that's the valuable part, just like anything else: finding people to help you learn and find your way along the path. Like I said before, biprops aren't necessarily any more difficult or dangerous than a hobby hybrid -- personally I'd rather be around 60,000 gallons of LOX than 60,000 gallons of N2O any day -- they're just dangerous in a different way. Many people seem to see the "different" dangerous as "more" dangerous -- it's not, it just presents a different set of challenges to be aware of. And though TRF is certainly not the proper forum for the discussion of the design, build, and testing of a biprop engine, I think we can be a little more supportive and point out the proper place to discuss, rather than simply stating "biprops are dangerous, don't do them."

Dave

You basically make my point. The RRS (Reaction Research Society) is the premiere "amateur" rocket organization in the world and the MTA (Mojave Test Area) is a professional grade test facility. There are a number of aerospace professionals in the organization, and they have a block house, remote propellant handling facilities and use established safety procedures developed over the past 6 decades.

You have an engineering degree, and as part of your undergraduate education, you designed, built and tested a liquid biprop. You were mentored by a number of excellent professionals, faculty and experienced technicians, and when you fired your motor, you followed all the established safety procedures that were developed by these folks. I don't consider what you did as unsafe because of the manner in which you conducted it.

But I also don't consider a degreed engineer an "amateur" aside from the fact that he may not be getting paid for his rocketry activities. Your statement "Hard starts are certainly a major problem with liquids, but one that is easily controlled with proper ignition sequencing, valve control, and purge systems. Proper propellant selection and modern computer control has simplified these issues dramatically." is the professional answer to my principal safety concern, but a typical backyard hobbyist is unaware of the potential problem or the solution.

I checked out the suggested video which was taken at MTA which appears to be quite professional as are other static test videos from MTA that I am aware of. That 4,000 lbf motor is consuming more than 13 pounds of propellant per second, and at that flow rate, a detonation resulting from a 20 millisecond ignition delay is equivalent to 1 pound of dynamite. I am reasonably sure that the professional MTA safety procedures require that the operators be in a block house to avoid injury should the motor fail. However in the related videos I found this https://www.youtube.com/watch?v=X3o-N6RT4eQ&feature=related where I see a person standing directly beside a substantial liquid motor operating a control panel without any shock/ballistic protection from a motor failure. IMO this is a cavalier, amateurish and down right dangerous practice and what I am discouraging because I know what will happen to someone when they're that close to a motor failure.

What is simple and well understood to the professional can severely injure or kill an amateur. It would be unprofessional of me to say otherwise.

Bob

 

[rockets2000]

After seeing that video, there is an angel on my left shoulder and a devil on my right....

 

[daveyfire]

What is simple and well understood to the professional can severely injure or kill an amateur. It would be unprofessional of me to say otherwise.

Stepping back and considering my reply in this light, I completely agree with your sentiments. I've had a lot of trouble keeping my hobby and my job separate!

(Usually that's a good thing, though )

 

[bobkrech]

Stepping back and considering my reply in this light, I completely agree with your sentiments. I've had a lot of trouble keeping my hobby and my job separate!

(Usually that's a good thing, though )

Me too but I wouldn't have it any other way!!!:clap:

Bob

 

[spacecadet]

I love the way the guy puts out his foot to steady the rig as it threatens to be blown over by the thrust. What a bunch of jerks. I don't even stand that close to a 1/2A motor.