ROCKET BOOSTED 1/8 SCALE RC CAR HELP

Discussion in 'The Watering Hole' started by arelee, Jan 11, 2020.

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  1. Jan 11, 2020 #1

    arelee

    arelee

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    Greetings,

    I am a new member to this forum, and model rockets in general.

    I am currently working on a project that involves incorporating a mode rocket motor into a heavily modified, for speed, 1/8 scale, electric rc car. Once the car has hit its maximum limit, the rocket motor will be engaged, to further increase the overall speed . Kind of like when nitrous oxide is applied to a full size race car.

    The platform I am using is an ARRMA Typhon 6s BLX V4. The projected speed of this car, (once it's modified for speed and aerodynamics), should be in the range of 120mph -140mph.

    These "speed runs" will take place on a flat, smooth, straight asphalt surface.

    I do not have a level 1 certification, so, from what I understand, a "G" rocket motor is the largest that I can use. Is that a fact?

    I want to use a motor that will give me the maximum thrust when activated. Also, one that does not include the charge that deploys the recovery parachute, ( don't want to burn-up the inside of the car).

    The placement and angle of the motor, along with the correct casing are other areas I need to consider. The amount of volts to ignite the motor is another variable.

    Any suggestions would be much appreciated.

    NOTE:
    If you are interested in more information regarding this project, go to "AARMA FORUM". I started (2) threads awhile back= ROCKET BOOST KRATON 6S and 8S, (about halfway down the thread, I made an update stating that the Typhon 6s BLX V4 was a better platform to use). Same project. Different car. The other thread=Typhon 6S BLX V4 MAXIMUM SPEED UPGRADE HELP
     
  2. Jan 11, 2020 #2

    dhbarr

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    Be aware that you are outside FAR101; and the NAR or Tripoli safety codes; and the manufacturer's instructions. Any insurance or fire disputes will be between you and the local authorities. Please calculate the kinetic energy of your projectile and plan safety accordingly. Consider a line to run along. How will you stop?

    12v is typical, you don't have a propellant weight limit since you're not in the airspace. If you use more than one G, cluster them vertically so a delay in ignition doesn't spin you.

    Aerotech g76 green in the 29/40-120 case would be my choice if I wanted an instant punch. g64w if I wanted the same energy but spread over 2.1sec instead of 1.5sec. Turn the c-slot in the up direction.

    You can put the delay in but leave out the powder charge. I recommend packing the charge well with blown cellulose insulation or wadding, then installing the powder cap.
     
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  3. Jan 11, 2020 #3

    jd2cylman

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    But for him, maybe the AT G80 might be better, or any of the AT 29mm G single use motors. No case to buy or reloads to assemble.
    Just a thought...
     
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  4. Jan 11, 2020 #4

    John Taylor

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    Do it on private property. Otherwise you may get in a lot of trouble.
    What could possibly go wrong?
     
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  5. Jan 11, 2020 #5

    jlabrasca

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    Arlee -- looking at your profile on the ARRMA forum I see that you only signed up there in November of 2019. Have your built RC cars not intended for rocket-assisted speed runs?

    This admission from the TYPHON 6S BLX V4 MAXIMUM SPEED UPGRADE HELP thread will cause a certain amount of worry for folks who post on THIS forum:


    As @dhbarr observes, your proposed use is very different from the intended (and regulated) use for the motors we put in rockets that go up. That is to say, while G motors are highest impulse you can buy without an L1 cert, what you are planning to do violates the safety codes for the use of motors of any impulse.

    https://www.nar.org/safety-information/model-rocket-safety-code/

    http://www.canadianrocketry.org/model_safety_code.php

    https://rocketry.org.au/safety-information/model-rocket-safety-code/

    and so on...

    The best advice anyone here will give will be NOT to do this; not only for your own safety, and the safety of people and property in the vicinity when you make the attempt. Rocketeers always worry that a tragedy involving an amateur or model rocket motor will lead to increased regulation of our hobby.

    This is a recent memory for many rocketeers.

    TRIPOLI ROCKETRY ASSOCIATION INC v. BUREAU OF ALCOHOL TOBACCO FIREARMS AND EXPLOSIVES

    If you are determined to make the attempt, then you should at least try to learn how rockets actually work. Some of what you have written makes it seem as if you do not understand how to do what you say you want to do.

    https://www.grc.nasa.gov/WWW/K-12/rocket/rktparts.html


    Good luck to you.
     
    Last edited: Jan 11, 2020
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  6. Jan 11, 2020 #6

    Rob702Martinez

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    :sigh: :(
     
    Last edited: Jan 28, 2020
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  7. Jan 11, 2020 #7

    arelee

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    Hello dhbarr.

    Being a novice to rockets, the terminology is new to me. What are: FAR101, NAR and Tripoli safety codes, and why am I out of them? How do I calculate the kinetic energy of a projectile? Regarding the line that I will be running on, it is straight and longer than I will need. Once the run is over, I simply let the car coast, then apply reverse, until it comes to a stop.

    Is the 'powder charge you mentioned, what deploys a parachute?

    Thank's for the information.
     
  8. Jan 11, 2020 #8

    arelee

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    Hi jd2cylman.

    Actually, no cases to buy, or reloads to assemble is what I'm looking for, (at least for now).

    Many thank's!
     
  9. Jan 11, 2020 #9

    arelee

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    Believe me, even without a rocket installed, safety precautions are paramount. This generation of 1/8 scale RC cars not only travel extremely fast, (especially when upgraded),they weigh a lot.

    I live out in the country. A safe place to run the car is not an issue.

    Thank's for your input.
     
  10. Jan 11, 2020 #10

    Rob702Martinez

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    :sigh: :(
     
    Last edited: Jan 28, 2020
  11. Jan 11, 2020 #11

    arelee

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    I appreciate your input. However, the reason that I joined this forum, is to find out what I can and can't do, and how to do it safely and correctly, not just strap a rocket onto an RC car. As I mentioned to another reply, safety is paramount with me. I live in the country. No houses, people etc... to endanger.

    For what it's worth, I am 68 years old. Not trying to be cool, or attract "chicks". Simply find out the best avenue to take for this experiment.

    I am 68 years old and am not trying to be "cool", or a "chick bait".
     
  12. Jan 11, 2020 #12

    Walter Longburn

    Walter Longburn

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    Just curious what this rc car weighs? The Aerotech g80 only burns for 1.7 seconds and its peak thrust is ~24 lbs.
     
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  13. Jan 11, 2020 #13

    arelee

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    Hello jlabrasca.

    Yes, I have built many, smaller RC cars. However that was back in the 80s, (I'm 68 years old). This new generation of cars is excitingly new to me, and way more expensive.

    The reason I joined this forum, is to learn about model rockets, and to understand my limitations, and the laws.

    I appreciate any and all positive and negative input.

    Thank's
     
  14. Jan 11, 2020 #14

    dhbarr

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    NFPA 1122 -- Model Rocketry
    NFPA 1127 -- High Power Rocketry

    FAR 101
    https://www.law.cornell.edu/cfr/text/14/101.22

    For purchasing or selling motors it's the CPSC, for shipping it's the USPS & NHTSA and your local DOT.

    https://www.nar.org/safety-codes-2/

    http://www.tripoli.org/SafetyCode

    These all apply to safety when flying in the air, but what you want to do is not that.

    KE=1/2*m*v^2
    OR
    mass x velocity x velocity, all divided by two

    You'll find your car has much more energy in it than many bullets; plan your safety accordingly.

    Instructions for assembling one of the reloads I mentioned:
    http://www.aerotech-rocketry.com/resources.aspx?id=4
     
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  15. Jan 11, 2020 #15

    arelee

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    Hi Longburn.

    The total weight is roughly 9 pounds.

    Thank's for the information. Every bit of advice helps!
     
  16. Jan 11, 2020 #16

    arelee

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    Thank's for getting back to me. I'll check into all of your links.

    Have a nice day!
     
  17. Jan 11, 2020 #17

    jlabrasca

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    You are welcome.

    Some corrections, clarifications, and amplifications:

    "click bait" not "chick bait"

    dhbarr was probably suggesting that you thread a taut guide wire (a "line") through a fixture on the car to keep the car moving in a straight line and prevent it (insofar as possible) from going airborne.

    You say "saftey is paramount", then please accept the judgment of folks who launch these rockets when you read that what you are proposing is much more dangerous than you seem to understand. The kinetic energies involved in rocketry are 10s or 100s of times greater than the kinetic energies developed by even the fastest wheel-driven RC cars. That the words "kinetic energy" do not seem to be familiar to you is an indication that you have to learn quite a lot before you are competent to assess the risk (nevermind working out solutions to mitigate that risk)

    And, as has been pointed out to you, even if you only hurt yourself or only damage your own property, your actions may negatively impact the hobby of rocketry. We would really prefer that you not do this.
     
    Last edited: Jan 12, 2020
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  18. Jan 11, 2020 #18

    Rob702Martinez

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    :sigh: :(
     
    Last edited: Jan 28, 2020
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  19. Jan 11, 2020 #19

    dhbarr

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    You're looking at about 7,000 Joules or about 5,000 ft-lbs. That's a little more than a Lapua .338 Magnum factory reload, but it's carrying two flammable solids that will spray everywhere if you tap a pebble.

    That's what I mean when I say be careful.
     
  20. Jan 11, 2020 #20

    arelee

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    I looked up click bait. I don't add links in any of my posts,here or on AARMA FORUM. Not my thing.

    Although the car is being built with aerodynamics in mind, for speeds exceeding 100mph, I realize that incorporating a rocket will change a lot. That's one of the factors I'm hoping to get help with. Threading a taught guide wire beneath the car sounds like something to seriously consider= safety and stability.

    I mentioned "G" motors. Maybe that is too big to start with. Again, I'm new to model rockets. Any suggestions are appreciated. This is going to take some time. I'm not in any rush.

    again, thank you.
     
  21. Jan 11, 2020 #21

    arelee

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    That's what I am looking into.
     
  22. Jan 11, 2020 #22

    Charles Botkin

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    Well you can be in for some serious speeds with this.
    Many years ago a small group of friends and I began constructing and running rocket powered dragsters.
    The first ones were of very simple construction with flat sheets of fiberglass to build the chassis and balsa to create the bodies,and included small fins for downforce which are greatly needed.
    For safety we used eyelets in the bottoms of the cars and steel fishing leader as a guide cable which are stretched out on a private tarmac runway.
    These cars started small at 1 ft long and used estes C and D motors to see how safe they would be then progressed up to 3ft long with an H motor.
    This is where we have stopped due to the tarmac only being 1 mile in length.
    We have tried using various r/c cars but even with a gyro in the steering are limited to keeping the thrust to 3/4 the weight of the cars, because there is no way to easily control the cars direction when ignition occurs.
    Safety Above all else,,, Start with a small engine and progress up slowly... Test test test
     
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  23. Jan 11, 2020 #23

    georgegassaway

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  24. Jan 11, 2020 #24

    blackjack2564

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    Arelee sent ya a Private message.Post here if ya can't figure out how to open it.
     
  25. Jan 12, 2020 #25

    arelee

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    Hey Charles,

    Thank's for the information about your rocket cars.

    I'll take your advice on RC cars while planning this portion of the project. Very helpful! How did you get past the part where the charge that is used to deploy the parachute ignites? It faces the interior of the car.

    Again, thank you.
     
  26. Jan 12, 2020 #26

    arelee

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  27. Jan 12, 2020 #27

    jlabrasca

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    Yes, person who just joined to make a post in this thread. Thanks for your timely and apposite comments. >smile<

    Is it really any more foolish to shout into the wind that it is to speak to the wind calmly and in measured tones?
     
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  28. Jan 12, 2020 #28

    BSNW

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    I remember seeing a photo of an old rocket motor package in some "old motor-photo" forum saying the motors were for rocketry and "scientific experiments" or something. So i think there are many safe uses for our hobby motors.

    I know many in the rocketry community are thankfully safety minded. If you ask anybody in my clubs they will tell you I am very concerned about safety and follow the codes. That does not mean that a hobby rocket motor that produces thrust cannot be safely used in other applications, if safety precautions are taken. That is like saying that the lawn mower engine I purchased cant be used to make my min-bike or go-cart.

    In reply to your quote that "A rocket motor outside of a rocket is not safe. Period."....I would submit that a rocket motor IN a rocket is likewise NOT safe either. It is how one uses said motor. Someone likewise posted a video of a rocket car gone bad....I too can provide some scary videos of ROCKETS gone bad. Come on....chill out and get a grip. This guy is (kindly no less) asking us questions, being open with his intentions and said he is doing this OUT of our country. He also said he is making attempts at safety......Before we get all self righteous about our safety in rocketry and post snarky replies to his questions...maybe we should likewise go to YouTube and see some if the crap our hobby has done.....give the guy a break. Respectfully.

    Let the piling on commence....
     
    Last edited: Jan 12, 2020
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  29. Jan 12, 2020 #29

    BSNW

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    My goodness the things we did in the 1970's - 80's and earlier....put Estes motors on balsa gliders...on model cars. Built forts in trees..made hot air balloons.....made mini-bikes. We did all sorts of crazy dangerous things. Some of us became engineers and scientists as a result of our "reckless and dangerous" activities. If not, we learned how to problem solve and work with our hands and minds....Dang...the world nearly blew up because of our behavior.
     
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  30. Jan 12, 2020 #30

    BSNW

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    Dude...that is just plain rude. Really...I dont mean this in a mean way...but respectfully (really)...get over yourself.

    Where were you guys when a British team took fighter jet engines and put them in a car....and set a land speed record!!?
     
    Last edited: Jan 12, 2020
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