New hi-speed project - Page 8 - RC-Monster Forums

01.15.2008, 10:05 PM

Wow, I was just looking at an f1 car and a pan car in a magazine. I was thinking higher speeds but not this high. Probably 60-70 just for fun in a parking lot. Now I am kind of think more 85-90. I think the pan car, not sure its called that, like the robotronic scalpel was 2wd,(no go) but the f1 was awd. I also like over powered drifting. Should be cool. I like just reading the info you guys post.

BrianG · 01.16.2008, 12:04 PM

In case anyone is interested: http://cgi.ebay.com/ws/eBayISAPI.dll...MESE:IT&ih=013

01.17.2008, 04:35 PM

Your roller looks nice, Brian. Looks a lot like my X1-CR chassis. I'm wondering if I'd be able to do a direct transplant of my buggy conversion into one of these...

Big House · 01.17.2008, 11:02 PM

I am looking at the same car and the same conversion but I just want 60mph with bullet acceleration. Any suggestions?

Mod Man · 01.18.2008, 09:32 AM

60 mph is easy. You could go with a Neu 1512 on 5 or 6S and hit that while still being driveable. If you are planning on running off road tires you will have problems, though. Make sure they are CAed very well.

Matt

Big House · 01.18.2008, 06:49 PM

Thanks Matt,

That helps alot. I will definitly be running street tires. I am looking to power the beast with two A123 6.6 packs in series. That way I can still use my Mamba Esc. Just got to find a motor I can run. I don't like the idea of endbell popping of motors.

Big House · **Manual brake with electric conversion -** 01.18.2008, 07:16 PM

How do you retain the use of manual brakes with an electric conversion if you don't want to use the ESC brake function?

bdebde · 01.19.2008, 04:50 AM

Quote:

Originally Posted by Big House

How do you retain the use of manual brakes with an electric conversion if you don't want to use the ESC brake function?

Keep the brake servo and parts, use a y cable for 2 channel radio, or hook brake to channel 3 on a 3 channel radio.

BrianG · 11:10 AM

Well, I have a Neu 1515 2.5d coming! With a motor kv of 1700, 8s lipo should be a decent match for 50k motor rpm. May go with 9s for 56k rpm, dunno yet. Either way, I'm gonna need a special balancer setup - probably pick up two Commonsenserc balancer units and make a custom 12s balancer. Dual LBA10s is just too much wire for my liking.

Also got another Koolflight UBEC. Keeping the voltage under 40v lets me be able to use the UBEC, otherwise, I'd need a receiver pack or some special regulator design. Technically, I probably could get away with 10s since it's 37v nominal, 42v max, but that's too close to the max input for the UBEC.

I haven't done much progress on the project though. Cut the body out and test-fitted it. Man, that thing is HUGE! The plastic guards don't even come close to touching the sides of the body (at least 1" gap) and there is so much room in front and rear of the chassis that I could easily fit the ESC, Rx, UBEC there. Might put the ESC in back on a custom tray and the Rx/UBEC up front. That should help radio range by keeping the motor wires quite far from the antenna and other low-level signal wires.

Made some fiberglass flat pieces to re-fab the servo tray, but the fleece is a little too flexible I think. So, I'm gonna pick up some glass matting, or a denser cloth and try that. Fleece is nice for curves and such because it stretches in all directions, but not needed for this. Maybe for the battery tray...

MetalMan · 01.25.2008, 11:20 AM

Brian, since you're gonna run 8s and have two balancers, are you gonna charge two 4s packs in parallel? If not, I can't imagine all of the cells being in the best balance possible without getting networked balancers (like 2x LBA10).

BrianG · 01.25.2008, 11:26 AM

No, in series. I'm going to take a look at the tolerances between the two and adjust the circuitry as needed. Or, maybe the main IC has some type of syncing input that I can take advantage of - that would make things easier. Either way, I'll "git 'er done".

Just go Play · 01.25.2008, 11:35 AM

Quote:

Originally Posted by BrianG

Keeping the voltage under 40v lets me be able to use the UBEC, otherwise, I'd need a receiver pack or some special regulator design. Technically, I probably could get away with 10s since it's 37v nominal, 42v max, but that's too close to the max input for the UBEC.

The other option would be to just run the UBEC off the first battery pack before the series connection. The wiring would not be as clean but it is an easy way to avoid the over voltage problem.

lutach · 01.25.2008, 11:42 AM

Quote:

Originally Posted by BrianG

Well, I have a Neu 1515 2.5d coming! With a motor kv of 1700, 8s lipo should be a decent match for 50k motor rpm. May go with 9s for 56k rpm, dunno yet. Either way, I'm gonna need a special balancer setup - probably pick up two Commonsenserc balancer units and make a custom 12s balancer. Dual LBA10s is just too much wire for my liking.

Also got another Koolflight UBEC. Keeping the voltage under 40v lets me be able to use the UBEC, otherwise, I'd need a receiver pack or some special regulator design. Technically, I probably could get away with 10s since it's 37v nominal, 42v max, but that's too close to the max input for the UBEC.

I haven't done much progress on the project though. Cut the body out and test-fitted it. Man, that thing is HUGE! The plastic guards don't even come close to touching the sides of the body (at least 1" gap) and there is so much room in front and rear of the chassis that I could easily fit the ESC, Rx, UBEC there. Might put the ESC in back on a custom tray and the Rx/UBEC up front. That should help radio range by keeping the motor wires quite far from the antenna and other low-level signal wires.

Made some fiberglass flat pieces to re-fab the servo tray, but the fleece is a little too flexible I think. So, I'm gonna pick up some glass matting, or a denser cloth and try that. Fleece is nice for curves and such because it stretches in all directions, but not needed for this. Maybe for the battery tray...

Brian,

There are some HV BEC out there: http://www.dimensionengineering.com/VHVBEC.htm and http://www.western-robotics.com/herculesHV.html. They also seem a bit smaller than the Koolflight unit.

BrianG · 01.25.2008, 11:56 AM

Yeah, I could do that, but then the packs would be out of balance. If I was going to a higher voltage, I'd just use a linear regulator to bring the V from whatever to ~38v, and then let the UBEC take care of the rest. Or, just use an Rx pack.

And, I'm going to most likely use a single pack, so I'd have to use the balancer taps to get half the pack voltage since there won't be a series connection. Of course, a 9s pack will be a specialty item, but 8s should be good enough.

BrianG · 01.25.2008, 11:58 AM

Quote:

Originally Posted by lutach

Brian,

There are some HV BEC out there: http://www.dimensionengineering.com/VHVBEC.htm and http://www.western-robotics.com/herculesHV.html. They also seem a bit smaller than the Koolflight unit.

Even better! I'll keep those in mind if I decide to go higher V. And I don't mind the Koolflight's size really. I have TONS of room on this thing!