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 16, 2020 #61

    gldknght

    gldknght

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    I'm confused. You say you are wanting to make certain you are not breaking any laws regarding this project. You have already been informed a few times that what you are proposing is illegal, but it seems you still intend to proceed with your plans. What is your thought process?
     
  2. Jan 16, 2020 #62

    H_Rocket

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    I think this is an interesting project. The hand wringers writing about this being illegal, immoral, and fattening are probably not lawyers, ministers or dieticians nor did they stay in a Holiday Inn last night. Folks here are very conservative with respect to the optics when the rocket motors we use are differently applied.

    A few points

    1) Listen to the people who say start small.
    2) Understand that many motors have a very steep spike on ignition and then taper off. It will be similar to your description of Nitrous - on steroids. Are you skilled enough to control a car that suddenly has a proportionally sharp increase in speed?
    3) You cannot throttle these motors, you hit the go button and you are committed.
    4) I strongly suggest you do this attached to a guide wire or have some other way of limiting the car’s path.
    5) When you test this, have absolutely as few people around as necessary.
    6) Be fully prepared for the motor to fail catastrophically, they do a small percentage of the time. Accept that this may turn your car into smoldering wreckage. What is referred to as a forward closure failure would basically fill your model with superheated gases and incinerate most anything that will melt or burn. On that thought I would not do this with a nitro powered car. For an electric, be prepared to deal with a burning lithium battery.
     
    Last edited: Jan 16, 2020
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  3. Jan 16, 2020 #63

    arelee

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    Hey H_Rocket,

    Thank's for all of the advice. It sounds like you may have tried this yourself, or know someone that has.

    1) Starting small. Absolutely. Very small.
    2) Again, starting small is the plan.
    3) Same as 1 and 2
    4) A guide wire is one avenue that I am considering. Another is attaching a set of lightweight, freewheeling wheels to each
    side of the car. Like training wheels on my first bicycle, but farther apart.
    5) I live in a very rural area. Except for someone "spotting" for me, I will be the only one anywhere near the runs.
    6) The car is electric. The rocket motor will be encased in an aluminium or steel box. Only the back end will be open. The
    LiPo batteries are more than capable of handling the the power that the "Mamba XL-X Extreme" ESC, (electronic speed
    control) will be using. However, since these speed runs(120-140mph or more) do draw so much power from batteries,
    they need a cooling-down period. Simply replacing them with "fresh" batteries is my choice. Plus, that will give me an
    accurate speed reading each time.

    Again, Thank you.

    Have a nice day.
     
  4. Jan 16, 2020 #64

    arelee

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    Hey blackjack2564,

    Sorry to be so late in responding. Thank's for the graphs, and the photos of the Typhon 6S BLX V4. Oyt of the box it is impressive. However That's not how mine looks like now.

    Many people use the Typhon as a platform for speed runs. Check-out my thread on ARRMA FORUM, titled: TYPHON 6S BLX V4 MAXIMUM SPEED UPGRADE HELP.

    At this point I have done the following:
    1) Replaced the shocks and shock towers with those for a "Limitless", ( In my avatar photo on this forum, the blue car on the left is a Limitless). VERY low profile, and firm suspension.
    2) "GRP TYRES"=GTXO1-S2. These tires/wheels are belted, so they don't balloon at high speeds.
    3) 2, 6s 5,000mAh 60C 22.2V batteries that will be run in parallel.
    4) Mamba XL-X Extreme ESC, (electronic speed control)
    5)Sealed "Fast Eddy" bearings, throughout the car.
    6)Replaced center differential with a "spool" gear.
    7) 26 tooth pinion gear for the motor.
    8) 1,000,000CST fluid for front and rear differentials.
    9) 7,200uf capacitor pack.
    10) "Drooped" all suspension arms, to further lower the profile.
    11) Purchasing a Custom GT body from "Delta Plastik", for optimal aerodynamics.
    12)TP4060 2450KV motor, (back ordered)
    There are still more things to do. I'll post some photos when it is finished, (if there is such a thing as finished).

    Why didn't I simply start with my "Limitless" as the platform for this project? I wanted to find out what was needed for this project with the Typhon first. The great folks on ARRMA FORUM have and are helping me. More than I ever expected.

    If everything pans-out, the Limitless is next in line.
     
    Last edited: Jan 17, 2020
  5. Jan 16, 2020 #65
  6. Jan 16, 2020 #66

    Rob702Martinez

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    :sigh: :(
     
    Last edited: Jan 28, 2020
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  7. Jan 16, 2020 #67

    Charles Botkin

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    Last edited: Jan 16, 2020
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  8. Jan 16, 2020 #68

    H_Rocket

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    Actually the fire I was concerned with was in the case of a motor failure the hot gasses could set the batteries on fire.
     
  9. Jan 16, 2020 #69

    Titan II

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    I did not see this posted in the thread. If it was, sorry....

    https://www.rocketryforum.com/threads/rocket-car-on-j-motor-reaches-626-mph.136919/

    I wish you success. BTW....I use a gyro on the nose gear of all my pulse and turbine jets. Something to consider "if" steering becomes an issue. Also, jets with a rear mounted high thrust line engine typically have a couple degrees of down thrust (back lower than the front of the motor) to mitigate pitch up tendencies when adding power.

    I wish you success and have fun.
     
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  10. Jan 17, 2020 #70

    KC3KNM

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    I've had really good luck with the GY440 from Futaba in my speed run cars. They make a variant specifically for cars, but it doesn't support narrow band servos like the heli variant does. I've slapped a GY440 on a car that wasn't even remotely drive-able and ended up with a car that tracked super well. A gyro is definitely a good recommendation for OP steering issues or not, it'll keep the car pointed straight if things get a little darty.

    I'm not sure where people are coming up with the idea that this is illegal. While it's against safety code for Tripoli and NAR, I can't find any actual laws against it. If you're not a member of either, the safety code has no bearing on your activities (and obviously their insurance wont cover you even if you're a member). Is there actually a law against this?

    Compared to some of the stuff I've seen R/C speed run guys do, I don't think OP is being reckless or side stepping safety. Seems to be taking a rational approach here. I wouldn't run it on a public road, even out in the boonies, though.

    @arelee do you have any drawings of your proposed motor mount? I'd definitely put some time into ensuring it's square and rigid, not something slapped together.
     
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  11. Jan 17, 2020 #71

    grouch

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    If you are not running on the roads then where? I can't imagine having access to something smooth and long enough to pull this off. 120-140mph obviously will eat up a lot of inches quickly. If you are running it on the road, I would do everything in my power to ensure the thing stays on the road. I can just picture the headlines about the grassfire set by a rocket car seeking going for a walk about.

    I did see where people were suggesting gyros, sounds like a sound plan. In the end, I thing a G might be a little underwhelming added to a vehicle already traveling a buck twenty. Maybe need a couple that can fire in stages??? Fire two in tandem?

    Any consideration for a failsafe? Chute or airbrake?
     
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  12. Jan 17, 2020 #72

    KC3KNM

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    I used to run at Kansas Speedway in their parking/back lot area. Plenty long to get up over 100 and nothing to really hit. If you get with a local SCCA club odds are they've got a spot where they setup their autocross courses that should be more than large enough. Some drag strips will also let you run there when they're not running races, but it varies depending on the owner. Kart track owners have been pretty cool about letting me play around when they're closed as well. There's lots of options.
     
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  13. Jan 17, 2020 #73

    gldknght

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    From the NFPA 1122 (National Fire Protection Act 1122 is the LAW governing the model rocket hobby!) Model rocketry safety code:

    Chapter 5, Prohibited Activities
    Article (3)
    Using a model rocket motor contrary to the instructions for its use.

    Show me a model rocket motor instruction sheet that shows you how to use the motor in an r/c car.
     
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  14. Jan 17, 2020 #74

    KC3KNM

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    Isn't NFPA the National Fire Protection Association? Can't find anything when substituting act for association.

    https://www.douglaskrantz.com/SCNFPACode.html

    Seems like some states may adopt some of these codes as law, but they're not really enforced. They're more of a guideline for organizations. Can you provide a link to the National Fire Protection Act? I literally cannot find anything, and it's more than possible I'm wrong here.

    Also assuming Virginia has adopted the NFPA suggestions as law,

    1.1.5 This code shall not apply to the design, construction, fabrication, maintenance, production, manufacture, launch, flight, test, operation, or use of rocket propelled model aircraft that sustain their mass against the force of gravity by aerodynamic lifting surfaces that support the aircraft during the entire duration of its flight in the air, but shall apply to the model rocket motors and their components that provide the propulsion for such model aircraft.

    I've never seen an instruction sheet that describes use in a model aircraft, have you? While not specifically outlined, R/C car usage is not actually prohibited.

    I'll ask again, is there an actual law against this?
     
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  15. Jan 17, 2020 #75

    blackjack2564

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    You guys forgetting the big easy? AT selling "trailer hitch" rocket motors. Those wereL's If I remember. Manufacturer themselves promoting rocket motors on back of pick-up trucks for show........remember?
     
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  16. Jan 17, 2020 #76

    gldknght

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    Right, Association. Whatever.

    Yes, the NFPA 1122 is the law. What part of that is confusing you? The 'Prohibited Activities' part? Prohibited means illegal. Not that hard to understand.

    And yes, there used to be rocket motors specifically designed for, and only used in, rocket propelled r/c gliders. I can't remember the size, (32 mm maybe?) but the motor diameter was not used in anything but r/c gliders.
     
    Last edited: Jan 17, 2020
  17. Jan 17, 2020 #77

    gldknght

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  18. Jan 17, 2020 #78
  19. Jan 17, 2020 #79

    arelee

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  20. Jan 17, 2020 #80

    arelee

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    Hi KC3KNM,

    Thanks for the info.. I'll look into it.
     
  21. Jan 17, 2020 #81

    arelee

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    I'll find out if there is an SCCA chapter nearby. No drag strips in my neck of the woods. Maybe in Richmond.

    Thank's for the suggestions!
     
  22. Jan 17, 2020 #82

    arelee

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    I've heard about using gyros, but haven't looked into it yet. I'll do that today.

    When I started this thread, a "G" motor is what I was thinking of using. I was also concerned that at 120-140mph., the rocket may not add enough thrust to increase the speed. Other members on this forum disagreed.

    I will be starting with smaller motors, and work my way up. If, bye the time I get to a "G" motor and it doesn't prove to be effective, This project will end. I hope not.

    Thank's.
     
  23. Jan 17, 2020 #83

    arelee

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    Maybe if this project proves to be legal, possible and safe, I will write an instruction manual.
     
  24. Jan 17, 2020 #84

    arelee

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    Very useful info Titan II

    Many thank's!
     
  25. Jan 17, 2020 #85

    arelee

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    Hey Charles,

    Thank's for the info and video. Why limit the amount of metal? If it's a weight factor, Believe me, that's not an issue.
     
  26. Jan 17, 2020 #86

    KC3KNM

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    I’m not sure why you’re unnecessarily abrasive in 90% of your posts here, it gets kind of tiring.

    Association and Act are quite different in meaning, “whatever” seems like a poor response there.

    Can you point to 1122 being the law? I can’t find anything that states that. Parroting what you’ve already said isn’t proving your point or helping anyone here. NFPA is an organization out to set guidelines that states and other governing bodies can use, which is about all I can find through some searches. Not a law making entity, unless I’m wrong. There’s been no clarification that says otherwise.

    Where does it prohibit use in R/C vehicles? The interpretation you have regarding use as prescribed by instructions would contradict the use of motors in gliders as is extremely common and even outlined in 1122. I’m not a lawyer or schooled in interpreting rules and regulations but chapter 5 article 3 is pointing to safe operation of the motors and advises you to follow the guidelines set by the manufacture for ignition and storage. If you were to take it as you’re saying chapter 5 article 3 would directly contradict 1.1.5. By your interpretation we should ensure everyone posting R/C rocket gliders here is using approved motors or start dropping their NAR/TRA memberships and reporting them to the authorities as it’s the law. Where does NAR/TRA stand on this? Despite the motor instructions stating for use in model rockets, people are flying them in gliders and R/C planes pretty frequently. Is an R/C model with a rocket a model rocket?
     
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  27. Jan 17, 2020 #87

    arelee

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    KC3KNM, if you are not already a lawyer, maybe you should be. I'd hire you in a heartbeat!
     
  28. Jan 17, 2020 #88

    Charles Botkin

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    Thank's for the info and video. Why limit the amount of metal? If it's a weight factor, Believe me, that's not an issue.

    We had various failures and tho no one was hurt and no property was damaged the end result was car parts flying well over 500 ft.
    The main reason for limiting the amount metal is to keep the total mass of the car down.
    When your car is free wheeling you have no breaks other than a chute if you install one and if it works, there is no 100% easy way of stopping the car once it is going.
    A lighter car is easier to stop and does less damage if it hits something.
     
    Last edited: Jan 17, 2020
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  29. Jan 17, 2020 #89

    bibbster

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  30. Jan 17, 2020 #90

    gldknght

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    If you don't like the tone of my posts, don't read them!

    NFPA rules 1122 and 1127 are the federal laws that our model and high power safety codes are based on. Every one in the rocket community seems to understand this except you.

    NFPA 1122 Sect 1.1.5. specifically says the code DOES NOT APPLY to r/c model aircraft. There is no contradiction there. It does not say the code does not apply to misusing rocket motors in r/c cars.

    Sect 1.3 details who is responsible for the ENFORCEMENT of the code. "Guidelines" are generally not enforceable by government agencies. Other wording in the rest of the code and definitions detail how the code is federal law. I'm not going to retype the whole code here. Anyone interested should go ahead and read it all themselves, it's not that long or complicated.

    Chapter 5 sect 3 says nothing about the storage or ignition of model rocket motors. It says "using" motors in a manner inconsistent with the instructions. This is obviously not intended for organizations, but is intended for the 'user'. A user is an individual.

    I have NEVER advocated suspending a rocket flier's or r/c flier's Nar/Tra memberships, although that does happen from time to time for those that regularly violate safety.
     
    Last edited: Jan 17, 2020

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