LiteSpeed: My speed record attempt car...

[Dagger Thrasher]

Wow...I wasn't expecting quite so much interest lol. Cheers for all the compliments!

Takedown: Whether I'll beat Nic's record is pretty doubtful, this being my first speed run car...but I'm gonna give it my best shot. Keeping the car in check at speed should be made much easier with use of the gyro, so that's one less thing to worry about. As for the aerodynamics...well, the mistake a lot of people make is to try and create as much downforce as they can to keep the car on the ground. This creates a lot of drag though, so it's much better to simply try to kill any lift that the car creates. The shell I'm going to use provides a bit of downforce (you need some), but should create very little low-pressure over the rear. A low-pressure area behind the rear windscreen of a car (like on a normal tourer body) can be the problem that causes a car to lift off. It's kinda hard to explain without images lol. Anyway, that shell combined with an undertray and the diffuser should make for a very low-drag car with enough downforce to put power down at speed.

Of course, that's all just words...who knows what's gonna happen at the event lol.

MTBikerTim: That's a really good point, but due to the design of the axle and the size of the 1515, the motor needs to be a minimum distance from the axle...so I'm having to go with a larger pinion/spur combo. I'll see if I can't get the pinions machined from aluminium and lightened to minimise mass, though. :)

Jnev: I'm going to try to shave every gram I can off of this car, so there will be some other option parts...but it doesn't look like any major custom parts will be needed apart from a lexan undertray. I'm looking at going with full titanium hardware, an aluminium or titanium main axle, shaving some aluminium off of the 3Racing parts I already have, etc...but it doesn't look like any big custom stuff will be needed (part of the reason why I chose this chassis - the parts count is so low! lol).

Othello: That's a really good point, and I spent a looooong time deciding on the power system. Neu state that the 1515 motors can endure 2700W output for 30 seconds (I'm assuming this is while staying over 85% efficiency?), and as each speed run will certainly be no longer than 15 seconds - more like 10 - it seems to me that it should be able to handle double that for a really short period. What really swung it for me is Novak's system. Their motor is smaller, and must've drawn a heck of a lot of amps to hit 118mph, and they had no problems with it. The 1515 is larger, running on higher voltage and is powering an even lighter chassis, so it seems to me that it shouldn't have any problems if I gear it right.
The cells will be under a fair bit of strain, but the same applies...if MaxAmps cells can supply the current to hit 118 with a HV-Max, the Neu 30C cells also shouldn't any any problems in a burst (he says...)

Linky to the Novak car:
http://www.teamnovak.com/events/07wo...car/index.html

I'm planning on using a Monster Max (providing it's out by then lol) without it's case to shave weight, which should be up to the task.

Anyone, please correct me though if I'm wrong with any of this...which I probably am, lol.

[othello]

After looking at some eagletree graphs of two high speed setups i came to the conclusion that 4.5KW shouldn't be needed for your small and lightwheight car.

Here is why:
. A 13.9KG (30.4lbs) 1:5 onroad car with 10s lipo, lehner 2240 needed around 4.5KW input to reach 95mph (145km/h). The graph can be found here (site is in german)
. A Rustler VXL needed 1560 Watt for 82mph. The graph

I know you reach for higher speeds and the faster you go the energy needed does not augment in a linear way. But i think you won't need 4.5KW at all. Your batteries should be able to provide it. I wouldn't count on a MMM to be able to provide 4.5KW. A high AMP flight ESC with slower ramp up time might do the trick as brakes might not be as critical for a speed attempt. If brakes are needed i would look into a MGM 22418 which should be able to provide up to 4.5KW. As you already stated those high power levels only last for a short period and judging from the posted graphes it seems as if your highest Watt peak will be shortly before you reach top speed. Holding top speed won't require as much power as accelerating.

Looking forward to see your final built and good luck with your speed attempt.