Ok. Keeps us posted with pictures and a video of your beast running.

Couldn't you just use a 2cell 1200mah lipo reciever pack with the UBEC... That shouldn't weight more than a few Ozs I would have thought...

Yeah, I could. I try to stay away from using an Rx pack altogether though as it's just one more thing to charge. Not to mention creating some type of LVC - but I've already designed a circuit for that.

Oh how about a123 2s1p - You'd hardly ever have to charge it and wouldn't need a LVC or a UBEC...

6.6v is a little high but doable no? The Spektrum will take the volts will the servo?

Yeah, that would be ok too. 6.6v is a tad on the high side, but do-able considering that 6 NiMH cells is usually around 6.4ish volts.

I've seen my 5cells Rx packs come out of the charger sometimes at over 7V. I think most servos can handle 7.2 volts and I've seen some digital one even list it.

2s a123 would be 7.2V off the charger. A littel on the high side, but I have considered doing the same thing in the past for my nitros. They only reason Ididnt was the dang battery boxes on the nitros were just a touch to small to fit the length of the a123s.

I wound up using 2 of the 1200mah LiFePo4 cells in seriies though with no isses. Same voltages as the a123, just smaller size and capacity.

I have a couple VHVBECs and love them! I would move you in that direction. I have had very good success with them.

That 1515 should rock! I run my 1515/3DF on 12S and it is absolutely gear strippingly wicked!

Matt

Well, since I got the 1515 2.5d(f) already (1700kv), I'm pretty much limited to something under 40v anyway, so the Koolflight will be fine. At 9s, that makes 56,610rpm, which is the max I want the Neu to spin. And, 9s maxes out at 37.8v right off the charger, so it works for the UBEC too. Perfect!

I don't know if I'll be able to hit the high speeds I was hoping for, but I hope 90-100mph is doable and would be fun! And when I just want to play, I can simply reduce the pinion for more manageable speeds.

The "only" things I need now are lipos, ESC, motor mount, and a bunch of fabbing. Ugg, this hobby is expensive!

You should be good for an easy 90mph (well, easy relatively speaking).

Above 80mph aerodynamics become a huge issue.

Oh, Nic Case called me and we spoke for 45 minutes yesterday (He had engineering questions). He is tooling up for this year's event! There should be some good cars this year.

Matt

Possible set-up for Ofna GTP
 

Motor - Mega Motor ACn22/35/1E (2550 Kv)
ESC - MM
Battery - 2 A123 3S1P 9.9 in series (19.8V)
CC UBEC
Geared to run 60+ mph (however I do that)

Any other suggestions, I am open to all facts and opinions.

OK, I've settled on either 8s or 9s lipo, probably 9s for more power. So, now I'm looking at some HV ESC options:

• MGM 12032.
  • Doesn't seem to be in stock right now
  • Kinda expensive at $450
  • Support/warranty would be a PITA
  • Highest current HV option they have. Don't think I'll need/want more but you never know.
  • Does have brake/reverse if I decide to use electrical brakes in the future. Probably not, but the option is there.
  • Looks to be my best bet so far as far as working out of the box.
  
  
• CC Hydra HV-120.
  • Not much information about this so don't know if it will work with a pistol radio for sure
  • Availability?
  • Need to swap out the water cooling for air cooling
  • Cheaper than the MGM at $345
  • Has the 180A and 240A options if I want to get crazy.
  • Support/warranty is definitely a plus.
  
  
• CC Phoenix HV-110.
  • I know I'd need a pistix adaptor
  • Highest current HV option they have. Don't think I'll need/want more but you never know.
  • Cheapest option at $270
  • Support/warranty is definitely a plus.

Decisions, decisions! :neutral:

Kontronik Jazz 55-10-32? No need for pistix adapter.

55A is too low current. I want at least 4-5HP. Thanks for looking though. They DO have an aircraft 120A 63v model, but it probably needs that adaptor...

They have just released a new range of controllers called the Jive. Biggest is 80HV rated to 12S and 80A continuous with onboard 5A switching BEC. No word yet on whether or not it'll have the car modes that the Jazzes have though...

Brian, 55A is the min rating. The Jazz 55 will do 100A. I've seen graphs of it in another forum. The Power Jazz will work with a pistol radio without the pistix thingy.

The new ones might not have the car mode. I downloaded the 2008 catalog and it will not have proportional brakes.

It just makes me nervouse to pull currents consistently that much higher than the rating. I was looking for a "solid" 100-120A continuous rating with higher bursts. The Jive 80A might be a better choice, if nothing but peace of mind. And since I'm not using electrical brakes, the proportional brake issue is not important.

What I'm looking for is an ESC with the following features (not necessarily in order of importance):

- 100-120A rating.
- 50v+ rating. I want to run about 15-20% under the max rating for reliability.
- Decent level of programmability.
- NO COGGING! Never had a setup that did, and don't want one now.
- Adequate heatsinking. I'm don't like temps above 130-140*F.
- Fast/easy domestic support/warranty service.
- No special signal translation devices needed (pistix)
- Adjustable LVC (can set the v/cell value). I like a 3.1v-3.2v/cell cutoff.
- Priced at $300-$400.
- High quality. I don't trust those ~$100 100A HV ESCs. If it seems too good to be true, it probably is.

The boat guys are having fun with the Power Jazz. From what I know about Kontroniks, the true AMP rating is a bit higher then what they say it is.

I would go with the HV110. I have 3 of them and LOVE them! Also, I have never needed a pix stix adaptor for any of mine. I am not sure why you say they are needed. I merely set my trim and EPA to work with it. No problem. I have run them with my Futaba 3PK and my DX3.

I love the USB programming. Very cool.

Matt

Oh, I pull 127 amps out of my HV110 on 12s and it runs fine. No heat issues what-so-ever.

Matt

Well, most aircraft ESCs are meant to use a stick throttle.

- Max throttle (2ms) for a pistol radio is max throttle for a radio.
- Neutral (1.5ms) for a pistol radio is half throttle for an air radio.
- Brake/reverse (1ms) for a pistol radio is min throttle for an air radio.

So, many need something to translate the signal so a pistol radio can be used. That's good that I don't need it! And nice to hear it doesn't heat up even with higher currents (I assume your 127A figure is burst?).

It looks like the HV110 is a winner then!

Yup, again, I have never needed any adaptors to run my HV110. It just works! In fact, it is far less throttle position sensitive (for arming) than my MGM Com Pro ESC.

Yes, that 127 amps is burst. I have pulled over 100 amps for relatively extended periods of time, though (6 second runs). I run mine run after run back to back with no heat issues. I did put a fan on it when the weather got really hot. But, it didn't need it. It never got hotter than 130 degrees according to my Eagle Tree temp probe.

I cannot recommend the HV110 enough, especially for the price.

If you have any programming issues or questions about it, call CC and ask for Joe Ford. You can tell him I referred you to him. He gave me great info on setting up my ESC for top speed use.

HV ESCs are all that Nic Case will run. We have spoken for extended periods of time in numerous conversations about this very subject. He and I are both very hard on equipment and we have both had fantastic luck with them.

Oh, wait till you see his TS car for this season! ;)

Matt

That's good to hear. I anticipate the majority of the current draw will be up to about 30-40mph and then drop to a more manageable level, so 110 should be fine. Programming it should be pretty straightforward, so hopefully won't need any help.

The only thing I'm a little concerned about is low rpm performance considering that it is geared so high. I'll know more once everything is hooked up.

Well, my TC4 is geared 1.8 to 1. That is geared for 150 mph wheel speed and I have no low speed issues what so ever. It just launches! It will tool around nice and slow or really launch with no cogging at all.

Oh, I get HUGE tire smoke even when the car is running 100 mph. You cannot appreciate high speed and crazy power to weight ratio untill you drive it! :mdr:

Matt

I can imagine! I'm looking at between 4.5-5HP in my rig!

I calculated 4.59 HP by taking the 3600 watt draw, calculating the motor and ESC efficiency and I came up with that number.

You will probably be looking at about 3.5 to 3.8 HP of actual power output when you take the efficiency into consideration.

That should be plenty of power for what you are doing. :mdr:

Matt

Not to throw a wrench in all this, but what about this ESC: http://www.hobbycity.com/hobbycity/s...idProduct=4691

12s @ 100A sounds nice to me. And since I'll be running 9s, it gives me a little headroom on voltage.

All the user reviews seem to think highly of it, and it doesn't need a pistix adaptor. Warranty/service might be an issue, but for the price, it's hard to pass up!

I would check out the Jazz Power 63v

FEATURES:
Handles 18-45 NiCd/NiMH cells and 5-15 LiIon cells 13-63V
NO BEC-receiver battery must be used
Automatic motor timing adjustment
APM (Auto Programming Mode)
Active free wheeling circuit increases efficiency at partial load
and reduces heat build-up
Audible start-up signal indicates which battery mode is active
Optocoupler for interference suppression
Built-in cooling fan
Reverse polarity protection

SPECS:
Cell Input: 18-45 NiCd/NiMH, 5-15 LiIon
Voltage Input: 13-63V
Continuous Current: 120A, 200A for 15S electronically limited
Weight: 7.8oz (220g) with cables
Length: 3.3" (84mm)
Width: 2" (51mm)
Height: 1.4" (35mm)

The problem with the Power Jazz is $$$$$$$$$$$$$$$$$

I've had good luck with it in my MT2 and a 4130 outrunner on 10s1p A123, geared for ~75mph. It runs cool, too bad the same can't be said about the motor. It's just too bad it takes up so much space!

Not much progress really. Just made a new servo bracket to push the brake servo out further to allow room for the motor and pinions. Had to make a new linkage as well since the stock one was too short. Also got my 1515 2.5d motor in. :smile:

The pinion on there is an 18T from the top shaft of an emaxx tranny to give me an idea of the room I'll have (plan to have a 20T pinion on first gear).

http://scriptasylum.com/forumpics/ultra_gtp_2.jpg

Now I think I'm gonna hit Mike up for a motor mount...

Looking good. I hope to see a nice video of that beast flying.

Me too! :smile:

Not much, but a little progress. Was away on vaca in SoCal and the previous week was pretty busy...

Anyway, got Mike's mount in the mail. Fits like a glove, but does require you to mod the stock spacer a little. All you have to do is trim the side edges. Really, only one really needs to be done, but I did both for consistency.

http://scriptasylum.com/forumpics/ultra_gtp_4.jpg

Also got the optional 44T 2nd gear along with Mike's 2 speed pinion adaptor and the 20T and 25T pinions. So, gearing will be 49/20 in first and 44/25 in second. Man those pinions are big! Was a little tough to get the mesh set perfect since the pinions are too large to fit the hex wrench in there to tighten down the motor screws. But I managed.

Also got the CC HV-110 ESC in as well. Castle said they would make a custom HV-110 for me so it was more like a HV-160, but we'll see how this one works first. If the ESC has issues, I'll spring for the added FET layer. The ESC will be mounted in the center for optimum wiring.

As you can see in the picture below, the side guards were removed. I plan to make new ones the correct width out of fiberglass. That should help undercar air turbulence as well as give me more room for the lipos, receiver, BEC, etc. Not sure yet if I want to mold the battery tray into those guards or keep it seperate, but the battery tray will be fiberglass as well. Glassdoctor was nice enough to give me a few samples of different fiber weaves to try out, so I'm pretty psyched. Just gotta get to Home Depot to pick up some lumber to make my tray molds and get my butt in gear...

http://scriptasylum.com/forumpics/ultra_gtp_3.jpg

I got a little anxious and temporarily hooked up an extra MM on 4s and ran it in the basement a little. All I'm gonna say is this thing will be fast! There was just a teeny bit of cogging, but I haven't updated the firmware on the MM yet, the wiring wasn't exactly optimal, and the gearing is kinda high. :smile:

Could I have a link to this build? I have been kicking around the idea of a TC4 but do not see to many people that build them?

Here's a link. http://www.rcgroups.com/forums/showt...=top+speed+tc4

I do not want to hijack this tread, though. You can PM me with any questions. I can shoot you my number too if you would like.

Also, Nic Case is a friend of mine. We have talked about the TC4 ALOT. Between the experience of the two of us, I doubt there is anything TC4/top speed related I cannot answer (and yes, there are a few MUST DOs with the TC4 that are needed for top speed running).

So, back on topic;

The HV110 will be plenty. Going with the custom HV160 is not needed. I pull close to 130 amps on 12S through my HV110 without any issues at all. It just runs and runs and runs. Amazing ESC. Now if they can just give the darn thing decent brakes.............:whistle:

Matt

Why would you want electrical brakes for a vehicle like this? IMO, the back-EMF would be too high (especially considering the high motor rpms, high gearing, and vehicle weight) for the batteries...

That looks good BrianG. Hope to see some numbers soon. I'm thinking of some MOSFETs to replace what they currently use and I found some amazing ones. I just have to see if I'll go with the 75V or a 60V one and if Patrick is willing to go with it :lol:. The current MOSFET is a Si4470 (60V, 12.7A cont. and 0.011ohms). My options looks like this: (75V, 45.8A cont. and 0.0133ohms), (60V, 30A cont. and 0.0092ohms). I might replace the MOSFETs on my Kontronik Jazz 40 first just to see if it works out. I know there are other things to consider, but it's worth a try.

There are 3 main reasons why I run electric brakes on my car;

#1 Space. Where is there room for them?

#2 Weight/complexity.

#3 Time to make and work out the bugs.

Innitially I wanted to make mechanical brakes. But, I found the electric brake to be perfectly fine even the poor HV110 brakes. It just takes a little fiddling to get the setting correct in the ESC.

The car stops wonderfully. Nic Case struggles with braking more than anything else. I have never had a problem getting the car to stop.

However, that being said, if I already had a car with mechanical brakes, I would definately use them.

Matt