K1RC

Hi guys as part of a competition myself and a couple others are building a rc rocket car, I just need some advice as far as bought in parts are going. Can someone give me a link to decent wheels, whatever people think will be best? Also any ideas for braking systems as the cars are judged on 0-100m-0 times and being able to carry an egg without breaking it , thanks in advanced

K1RC

Bump, really need some help please!

valk

iTrader: (13)

are you building this car from scratch or converting one? Id think a 4wd nitro car would be your best bet, an old one like an ntc3 as its cheap and will give you hardware brakes. you could probably convert a pancar to have a brake disk instead of a gear in the dif and use some nitro car braking system there but brakes on rear wheels only and will spinout.

ntc3 with rubber premounts and your rocket business would be my choice maybe.

K1RC

If can get hold of some parts cheaply it would be good to do that but I think it'll be difficult to get a whole car together... Surley if the rocket has stopped and there's enough weight over the rear it might not lock? Do you know of anyone who has used parachutes or a way we could?

valk

iTrader: (13)

nitro car brakes are plenty good enough to stop the car at 100. dont worry about that. its more about the tires. at least using a 4wd car you get front brakes too. ntc3's come up around here cheaply. there are other options too but the ntc3 is the simplest.

K1RC

I'll have to talk with other people in my group and teachers about buying a car but yeah it looks like I could get one for around or under £100 which isn't too bad, just worried about stability because its quite short and not too wide in comparison to a proper drag car etc... If I put solid shocks on could that help it squatting etc?

valk

iTrader: (13)

just stiffen the shock oils and springs.

just recommending it as it would be a lot less time than trying to design your own. if you wanted to go a step further though, you could cut part of the body to raise up like an airbrake when you slam on the brakes. or pull a pin on a parachute. these will help to slow the car down abrubtly, but you still need friction brakes to come to a complete stop.

K1RC

Cool thanks well I'll need to talk to my group and stuff to check the rules allow bought in cars etc but it should be ok, I'll let you know how I get on, Cheers

IndyRC_Racer

iTrader: (9)

When I was in middle school/junior high, our science teacher let us launch rocket cars down the halls. We used a basic pine wood car attached to a line. Boy did it fill the halls with smoke and sulfur smell.

The thing to keep in mind with solid fuel model rocket engine is burn time and whether or not they have a parachute eject blast, second stage blast, or no eject blast at all. Make sure to pick the appropriate motor to get the result you are wanting.

As far as slowing down the car after the burn, you could use the parachute blast to initiate your braking process. Here are some ideas:

- Use a U-shaped tube for the engine and nose cone with parachute. The parachute blast should eject the nose cone. The car should slow down like a drag car. Make sure to use blast cotton to keep the parachute and cord from being burned in half. If you use a large parachute, make sure it is mounted high enough to allow it to fully deploy

- Use the parachute blast to burn through a control string that will engage a braking mechanism. You could have a spring loaded friction brake that will engage when the string breaks (Think simple brakes on horse drawn vehicles)

- If you can use an R/C car platform, you can use a mechanical brake as others have suggested. If you aren't able to remote control the vehicle, you might be able to use the parachute blast to initiate the braking mechanism.

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If rolling resistance isn't an issue, then any wheels should work. If not, you should look into drag cars wheels (Traxxas) as they will be super thin.

K1RC

The rockets are being given to us by the bloodhound ssc team hosting the event so they are a control part. The string burning idea sounds great, although I would just be worried about reliability, either the string burning through to quickly and the car not performing correctly or worse, not working at all and having no brakes Do you know the dimensions of drag wheels? Also because they mostly seem to made of foam is there a possibility they could burn? Thanks for the ideas though, big help

IndyRC_Racer

iTrader: (9)

Traxxas makes a 1/8 Funny Car that comes with rubber wheels. Here is a link to the parts manual that lists parts including front rubber tires which are listed as $18 USD assembled (http://traxxas.com/sites/default/fil...rts-120301.pdf)

Here is a picture of the car without a body

IndyRC_Racer

iTrader: (9)

If you are going to use a 4wd 1/10 touring car as a base for your vehicle, you could also go with setup station wheels. These type of wheels are very narrow and mount directly to a standard touring car in place of normal TC wheels. They have a thin strip of rubber around the aluminum.

If there is a local r/c club or track near you, you might see if you can borrow some from a local racer (and save some money).

Here is an example of a set made by Integy (http://www3.towerhobbies.com/cgi-bin...?&I=LXKWM0&P=7)

valk

iTrader: (13)

setup wheels have an oring around them which isnt fixed in any way. sure, they will have low rolling resistance but there is a high likely hood they will fly off, or when you hit your friction brakes, they will come off. id run standard 24mm TC tires but run the hardest compound you can get. so maybe hpi tires or some sort. drift tires would work but wouldnt stop you that well.