Air Power

[gpraceman]

WeldingRod,

[sporty]

Thanks for sharing the info and yes pictures.

Went I looked at this a few weeks ago.

I seen they were like $15.00 each and not including shipping.

I wonder and still do, how much differeance is there from what i ran, the two 9 volts, running 18 volts, the lithuim batteries. about $8 each.

There are 1000 milliAmps in an Amp.

So 5 amps, thats impressive.
Sporty

[WeldingRod]

The Maximum Velocity link has a good picture, but I can't seem to find any of the ones I took!
Yes, the capacitors are expensive, but its the only way to get real current. Alkaline 9 Volt batteries pull down to something like 5 Volts at 1 Amp almost immediately. See the discharge curves on http://www.powerstream.com/9V-Alkaline- ... ?nowritefs" target="_blank Lithiums are significantly better (and lighter), but their short circuit current starts at 3 Amps and drops to 1.25 Amps after about 1 minute. Their load charts are here: http://www.batterymart.com/images/u9vl-charts_lg.gif" target="_blank The fans are rated for 5 Amps and up.

Rod

[emaier]

WeldingRod or anyone else, can you shed a little light for the electronically impaired? I know that running the capacitors in series in cumulative on the volts (2X5V caps in series gives 10V). From your post above, it appears that running in series does the inverse on capacitance (correct word?), i.e., two 5 volt 3 Farad capacitors, fully charged would give 10 volts with 1.5 Farads. Did I read this correctly?

Does the Farad rating have anything to do with how fast the capacitors charge up or "dump" the charge? Or is there some other measurement for the "speed" of a capacitor. I assume there would be a happy medium. Faster charging leads to faster dumping. Slow charging leads to a slow dump. The write-up on the MaxV kit states that with at least 5 seconds of charging, the fan runs for 10 seconds. Would changing the F measurement alter the charge and dump speeds?

Thanks

[Mike S.]

Hi everyone. I built one of the Max Velcocity fan cars last year and added the capacitors. It was the fastest at our adult derby. This year I am putting together another ducted fan car. I want to run two 9v batteries in series to four 5v 5 farad capacitors in series to supply 18v+ and a bunch of current to the fan. Having a hard time finding a fan that would work. Most are brushless and I don't think I can run a brushless motor because of the ESC. Not sure the ESC would know what to do with varying current as the capacitors discharge. The Hyperflow 56mm ducted fan with the 370BB brushed motor is on my radar but looks like everyone is sold out of those. Anyone have any ideas? Thanks for the help.

[Speedster]

I have a propellor powered car using the electronics from the Losi Mini-T RC car. Everything is available for the Losi Mini-T. It can be upgraded from 4 - AA batteries to brushless motors and Lipo batteries. My propellor car and wheel driven cars use the 7.2V Nickel Metal Hydride batteries. Since some folks are held back by weight limits, here are some of the specs:
Losi Sport battery - 7.2V 1100 mAh, 4.4 oz.
Helotes battery 7.2V 1400 mAh, 5.1 oz.
Receiver/speed control ( It is all in1 unit) maybe 5 grams
I weighed 2 Duracell 9V batteries at 3.2 oz so the Losi Sport battery might be light enough to use. It is only 1.2 oz. heavier than 2 -9 volt batteries. Has anyone tried wiring one of these batteries directly to their motor. If memory serves me a Lipo battery is 11.1V, has an insane amount of power, has a tendency to explode, and would probably burn up the Losi ESC. But maybe not for that short burst. I have a Mamba brushless motor system in one of my Mini-T's but it comes with its own speed control set up. It's very light and probably could be used in this application.
Cost - The best way to buy a Losi Mini-T is on ebay. With patience, you can usually acquire one with Nickel Metal Hydride batteries, modified motors, a battery charger and maybe chrome wheels. The wheels don't add any speed but they look cool. You now have an RC car to play with when it isn't derby time. You should be able to acquire a nice car for less than $80.00. At Derby time you can fire up your motor before the pin drops. If they won't allow you to do this it really doesn't matter. Your motor will reach top speed instantly. I like to do a "Burn Out" with my wheel driven cars to heat up the rubber. I'm allowed to do this because I own the track. It's Great Fun and the kids love it. The Mini-T has 6 channels so you can race cars against each other.
Good Luck to everyone with the Air Powered cars.