shutting down a solid rocket.

Charles_McG said:

Second that.

Also please consider:
- solid rocket motors aren't 'light'. They are high thrust, but actually quite heavy for the amount of impulse they provide.
- most propellant burn rates are -very- sensitive to chamber pressure. See post 2. Jettisoning the nozzle would kill the thrust even if the motor doesn't stop burning.
- anything you try to inject into the motor will be against that chamber pressure, and increase it, maybe over the burst rating.
- Hybrid rocket motors have a solid fuel and controllable oxidizer. I think Scaled Composited only killed one person developing the motor for SpaceShip One.

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i used to go out to mojavie...... i am a composite mold maker, worked for alot of ski boat companys & fiberglass shops.

rcktnut said:

I think you would be better off with figuring a full burn motor with the characteristics needed to achieve what you wish to accomplish with the vehicle.

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you are right, i am of course safety minded...... this is the safety part...... any useful safety device is studied for this application......

here is a file on the krushnic effect !

with the cars it is a 6 mile race track, ..... so to do the speeds that i am thinking of could use the prepped burn time calc.

LARRY A ROSA said:

here is a file on the krushnic effect !

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did the krushnic effect file upload ?

the safety device i am looking for is ........... instant stop of all propusion of a solid rocket...... so far the KRUSHNIC EFFECT looks to be the best set-up by far........... thanks !

summer testing........

today is 3/2/2020...... elon musks rocket ship crashed today, sorry to say.

a lever operated machined multi piece end nozzel that fits together to form a solid nozzle that can be opened and closed with a lever........ the zero instant propulsion could be attained ?

The typical solid APCP motor when burning has an internal pressure of several hundred PSI or more. I don't think the idea of a multi-piece nozzle will work as it has to withstand +2000 degrees F and several hundred PSI during the burn.

do you guys water cool the solid rocket nozzles on your rockets ?

once that lever is put into position & the machined multi piece nozzle is fit together leakage would be minimal.....
& the actual multi piece nozzle could even be a 2 piece build with running water cooling.....

the difference that i have in my application is that with a car....... to mount the rocket engine into has vast amounts of space...... no problem to run a water tank & pump...... al be it very small tank & pump batter.

its like this:

you sit in the car ready to push the button...... you push the button.....& decide that this AIN`T getten it......& want to shut it down...... pull the lever & instant coasting mode !

sounds good to me......

We don’t cool nozzles for solid propellant. We use nozzles that withstand the heat for the short time they’re needed.
Test it unmanned first. At the moment you open the nozzle you have much more area at a high pressure and a greater mass of gases will be released. I think you’ll experience a spike in thrust followed quickly by a precipitous drop off in thrust.
Ejecting the nozzle would result in an even greater spike in thrust and quicker drop.

Blowing out a side panel will result in sideways thrust.
Action = reaction is unforgiving.

Solid motors are not normally water cooled and we go out of our way to prevent gas leaks by using o-rings and similar. Many times has a nicked o-ring resulted in a very failed motor. We use graphite or similar nozzles and if they get wet and then used in a motor, you can get a steam explosion. Either ablative materials like the case liner or thermally stable materials like solid graphite nozzles are used.

Airplane Jet engines use thrust reversers:

https://en.wikipedia.org/wiki/Thrust_reversal

But the exhaust is probably not as high energy, i.e. - hot and high speed, as a solid rocket plume.

Because if there was a way to actually do what you are asking, we might have an additional space shuttle and an extra seven astronauts.

From the wikipedia entry on Shuttle Abort modes:

Once the shuttle's SRBs were ignited, the vehicle was committed to liftoff. If an event requiring an abort happened after SRB ignition, it was not possible to begin the abort until after SRB burnout and separation about two minutes after launch.

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(Yes, I know I'm glossing over the details of the Challenger Incident. But NASA doesn't know how to shut down a solid rocket motor once lit. I'm still voting for Steve's solution - blow the motor up and leave chunks of burning propellant in your wake.)

If you're asking how we cool our motor nozzles, then you don't really have a grasp of what model rocket motors are. Except for extremely advanced high power rocketry and university projects, there is no active cooling whatsoever. The nozzles are machined out of solid slugs of hard, ablative materials like clay, graphite, composite high temperature plastics, phenolic compounds, and some metals.

I suggest you research what is and is not a hobby rocket motor and then reevaluate the applicable information to your project. Apogee Components has a great source of information regarding basic understanding of model rocket motors. I suggest you start reading where it says "What is a “Black Powder” vs “Composite” motor?"

https://www.apogeerockets.com/Rocket-Motor-Basics-Quick-Start-Guide?m=quickside

Maybe I missed it somewhere... Why do you need to instantly shut down a solid rocket motor?

LARRY A ROSA said:

its like this:

you sit in the car ready to push the button...... you push the button.....& decide that this AIN`T getten it......& want to shut it down...... pull the lever & instant coasting mode !

sounds good to me......

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CoyoteNumber2 said:

Maybe I missed it somewhere... Why do you need to instantly shut down a solid rocket motor?

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It doesn't sound good to me!! Reminds me of:

Oh boy.

what metals do you use in machining the nozzles for the rockets...... i have looked at this aspect of the nozzle before & found that some metals will take 5000 degrees .

so that may not be a problem.

ebruce1361 said:

If you're asking how we cool our motor nozzles, then you don't really have a grasp of what model rocket motors are. Except for extremely advanced high power rocketry and university projects, there is no active cooling whatsoever. The nozzles are machined out of solid slugs of hard, ablative materials like clay, graphite, composite high temperature plastics, phenolic compounds, and some metals.

I suggest you research what is and is not a hobby rocket motor and then reevaluate the applicable information to your project. Apogee Components has a great source of information regarding basic understanding of model rocket motors. I suggest you start reading where it says "What is a “Black Powder” vs “Composite” motor?"

https://www.apogeerockets.com/Rocket-Motor-Basics-Quick-Start-Guide?m=quickside

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i have seen the black powder motors and watched alot of videos on rocketry..... cool stuff.

https://patents.google.com/patent/US7788900B2/en

search on "Throttle Control of an Extinguishable Solid Propellant"

figure out how to do it, then take the IP to an aerospace manufacturer with a NASA or ESA contract.

I once used 4000 gallons of water to shut down a free-burning 54 mm grain - 2.5 inches long. it took less then 4 seconds to dump the vast majority on the grain.

but it was a staged demonstration with my fire department's tanker :>

LARRY A ROSA said:

its like this:

you sit in the car ready to push the button...... you push the button.....& decide that this AIN`T getten it......& want to shut it down...... pull the lever & instant coasting mode !

sounds good to me......

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you want a liquid fueled rocket engine.
if it was poissible to shut em down, NASA wouldnt have had a self destruct device on the space shuttle SRBs

LARRY A ROSA said:

what metals do you use in machining the nozzles for the rockets...... .

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A lathe.

In all seriousness, I'd be leery of providing any insight to the inquiry because anything that is offered and utilized in the final solution, that results in damage, or worse, loss of life, could theoretically be used against you in a court of law...

Can you show us your design for your car ? I am intetested how you designed and built a 48 foot rocket car . What kind of materials do you use ? Does the cage or chassie need to be certified ? What is your end speed goal . You mentiond our hobby rocket motors . What size motor are you thinking of using ?

Our motors are not a good choice for a project like that. They are intended to be launched vertically. If a problem causes the motor to over-pressurize, our motors are usually designed so that usually one of the enclosures will fail so that the debris goes up and down, not horizontally towards people or property. And, of course, our motors are not meant to be able to be shut down.

The Rocket Racing League used hybrid motors which, I think, they could start and stop and possibly throttle. That type of motor would be better suited for a car.

OK......... i found it...... i always had it in my mind...... though,
this is how to shut down any full on solid or liquid rocket.................

first thing is to have the correct materials for the nozzle, a new metal called TANTALUM has a 7000 degree limit.
THAT WILL DO.

here is the way a rocket will be shut down......liquid or solid, ......

the nozzle is machined to end up in 2 parts, like a clam shell, the nozzle is hydraulically actuated , it opens and closes powerfully...... it has metal strip lines that ...... when it hydraulically closes it seals the nozzle so only the circle is used to pass fuel through.

that hydraulic system is only used in the event of an EMERGENCY......... when it is nessasary to stop propulsion.

the hydraulic system is super powerful............ it smashes those 2 movable pieces together .


i at this time want to release pictures of the new CAR...... it is built to 1600 mph.

the pictures below are similar to what is in the process of being built.

the liquid rocket bike ....... went over 200 mph.

Larry, do you have any data on how powerful a rocket motor you tuink you need, or where are you intending to get this rocket motor?

what i am building is similar to this rocket car.....it was a solid propelent car that went 585 mph.

Nytrunner said:

Larry, do you have any data on how powerful a rocket motor you tuink you need, or where are you intending to get this rocket motor?

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well i have an idea.....i want to have variable rocket power, 100 mph. 200 mph. 300. mph 400 mph. 500 mph.....etc.

it wont be long before i have it all......... plus it will be a SUPER BLAST to do the test runs on low to high power !

you guys should build some of these variable engines for rocket car ...... people.

rocket cars are going to take over....... for speed cars...... why put thousands of $$ into motors that blow up....like v-8s...when one can build WAY more powerful and dirt cheep rocket motors & go faster that any v-8. ?

its a sort of new field......... it is also W-I-D-E......... open to new americans who want to race.....only the only thing that is available is way out of site ................ 50 year old ........old man junk ?

so................ ENTER THE ROCKET !

LARRY A ROSA said:

variable engines

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Are you talking about solid propellent rocket motors or liquid propellant rocket engines? Your theories on "stopping the solid rocket" are going to run into serious physics and material limitation problems