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Old Jun 06, 2007, 08:22 PM
---------Speed!!---------
Illinois
Joined Jul 2003
6,134 Posts
Discussion
New CF supercar is born.

Well, I have been talking about this for a while and I felt it was time to show my car. For those who just want to know "How fast is it?" The simple answer is--------- I don't know. That is, I haven't had it wound out fully yet. I have seen 115mph on 6S while still accellerating big time. On 12S (different motor), the car went by at 100+ while wheel spinning an indicated 140 mph (4wd). Since then I have installed BSR cap tires. These tires hook very well. With the caps, the car has run 83mph at less than 30% throttle (in two seconds) and 100mph at 60% throttle. The weather stinks right now and the car has officially become faster than my street will allow. So, I am looking for a suitable runway to really wind it out.

Anyway, the car setup is as follows;

-Neu 1515/3D
-Thunder Power 2070 Extreme cells (12S)
-Castle Creations HV110 ESC
-Spectrum DX3 (love this radio)
-Futaba GY502 Gyro with digital steering servo
-TC4 drive components (basically stock other than a modified center driveshaft and 1 inch stretched wheelbase).
-BSR cap (radial) tires. AWESOME tires!
-Complete Eagle Tree data logging system with all accessories.
-Venom Speed Meter for wheel speed data (I have a radar gun too).
-CNC machined carbon fiber/plywood laminate chassis. This is an item I designed and made in my shop on my CNC with 7mm thick CF/ply laminate that is made to m y specs by my CF supplier for my helis products.
-CF body. I hand made the CF body by making a foam mold and laying the CF over the mold. The body by itself weighs 10.5 ounces. I need to thin it from the under side to shave a couple ounces.
-All up weight is 93 ounces.

The aerodynamics of this car are such that I have good downforce, but low drag. I did a HUGE amount of research and testing to come up with the final design. The front wheel wells are needed for front wheel steering clearance. I did quite a bit of testing to assure that the net drag of those wheel wells is zero. Also, the nose of the car went through numerous changes (hence the added body weight) to achieve the correct downforce/drag ralationship. I am not going to devulge the specifics of what I found as it is too lengthly to get into here.

The power system draws over 3800 watts continuous at full throttle. Also, the car accellerates at over 2.6 Gs (2.98 peak) and corners at roughly 2.5 Gs. (This is all data I have logged on my Eagle Tree).

Originally I speced the car for a Neu 1512. However, that motor built up with too much heat. So, I went to the 1515 you see with a finned can. That gave me a tad more power with a large improvement in heat dissipation. I also mounted two fans to the ESC and one to the motor.

When I got the car to the running point, I quickly found the motor heat issue and secondly, traction. Oh, also, the foam tires only last a few runs. So, I contacted John at BSR tires. He set me up with some touring car caps. These tires have good hook while allowing some wheel spin to protect the driveline from all the horsepower. They are also very long wearing. I am thrilled with the caps! Now, I just need to see if they will handle full speed.

I have about 30 to 40 hours in the body and about 30 to 40 more hours in the rest of the car (fabrication time only). Then I have about 5 hours in component programming and setup. Beyond that, I have about 100 hours in two previous TC4 setups to learn the drive system and what is needed for world class speed. So, this car has been hugely time consuming to develop.

At this point, the car has crazy horsepower (4.5hp), is super fast, handles (corners) very well, is reliable, runs relatively cool, and is very stable at high speed.

By far the most difficult part of the project was matching all components to work together, matching the drive system to the weight of the car and the CG, and getting the aerodynamincs matched to the chassis and capabilities of the car. When you are pushing the edge of the envelope, matching equipment and individual component setups is super critical!

Oh, I have so much power that gearing has proven to be only minimally important. I have gone up a few teeth and down a few teeth with very little affect. Basically I have it geared for 150 mph at full throttle under load. We shall see what it will actually do.

Anyway, I think that is it for now. I will give more information as questions are asked.

Matt
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Old Jun 06, 2007, 09:38 PM
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adamg's Avatar
Saskatoon, Canada
Joined Feb 2004
1,494 Posts
<--- speechless
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Old Jun 06, 2007, 11:47 PM
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Nexzzt's Avatar
Australia, QLD, Kippa-Ring
Joined Apr 2005
810 Posts
Wow, that thing looks fast just sitting there and the specs are amazing!

Quick question, are the Neu motors good for racing? Do you know if they make a 540 size brushless, im setting up an RC bike for mod/open class racing.

Cheers
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Old Jun 07, 2007, 01:11 AM
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adamg's Avatar
Saskatoon, Canada
Joined Feb 2004
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There is nothing Neu that fits in an application designed for 540 sized brushed and brushless.
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Old Jun 07, 2007, 05:56 AM
Love is like Pi: Irrational
ronmeister's Avatar
USA, ND, Grand Forks
Joined Jan 2005
2,159 Posts
How did I KNOW this was going to be you?
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Old Jun 07, 2007, 07:17 AM
---------Speed!!---------
Illinois
Joined Jul 2003
6,134 Posts
Thanks Guys.

I have been working on this car for a very long time and it is starting to pay off.

I ran it again since posting (just drove around my street). The tires really heat up if run hard. They get over 130 degrees! When they heat up, the traction is phenominal. Even at 93 ounces, the car handles great. It will not win any touring car races (unless there are a few very long straightaways), but it handles much better than you would expect from a straight line, top speed car.

Matt
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Old Jun 07, 2007, 08:47 AM
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adamg's Avatar
Saskatoon, Canada
Joined Feb 2004
1,494 Posts
Matt, what alignment settings do you run in a top speed car? Zero camber, 6* caster, no front toe, and little rear toe?
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Old Jun 07, 2007, 08:57 AM
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flyinazn10's Avatar
United States, CA, Long Beach
Joined Oct 2003
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DAH that is insane!
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Old Jun 07, 2007, 01:18 PM
---------Speed!!---------
Illinois
Joined Jul 2003
6,134 Posts
Quote:
Originally Posted by adamg
Matt, what alignment settings do you run in a top speed car? Zero camber, 6* caster, no front toe, and little rear toe?
You are very close. I run no toe in up front and VERY little at the rear (about 1/4 degree).

I am still messing with caster. Honestly the gyro makes chassis setup less critical. The big issue is getting as much of each tire on the ground as possible. Totally eliminating wedge is one of the biggest serects to traction with this car. Oh, I run no sway bars. I get a bit better traction without them. Not too sure why.

Matt
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Old Jun 07, 2007, 02:08 PM
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Cape Town, South Africa
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Speechless too...
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Old Jun 07, 2007, 05:21 PM
Who needs a pilot??
danstrider's Avatar
Alexandria, VA
Joined Jul 2002
1,161 Posts
What's the Zlog for? I think I see it tucked in the nose opposite the little lipo on the front bumper.

Thanks
Dan

PS: I'm not a car guy, just poking around and curious
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Old Jun 07, 2007, 05:46 PM
---------Speed!!---------
Illinois
Joined Jul 2003
6,134 Posts
That is the G-force sensor. That thing is super accurate. It senses G-force changes as little as .01 Gs. I get G-force samples 10 times per second with the data logger.

Matt
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Old Jun 07, 2007, 05:53 PM
Who needs a pilot??
danstrider's Avatar
Alexandria, VA
Joined Jul 2002
1,161 Posts
Thanks Matt.

I just read the other thread about your development. It's awesome to see technology cross the boundaries, referring to the gyro and eagletree in particular in the car app. Very nice work!

Dan
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Old Jun 07, 2007, 06:11 PM
Love is like Pi: Irrational
ronmeister's Avatar
USA, ND, Grand Forks
Joined Jan 2005
2,159 Posts
It looks great!
Reminds me of the Batmobile.
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Old Jun 07, 2007, 06:20 PM
---------Speed!!---------
Illinois
Joined Jul 2003
6,134 Posts
Ron,

That is about the 8th or 9th time I have heard that.

How about the Matt-mobile?

Dan,

I know. That is part of what drives me in this project. I found that "Average" heli stuff was considered wildly exotic to the car guys. Also, my machinshop skills developing helis really transferred over well on this project.

The typically aircraft stuff on this car are;

12S Thunder Power Extreme cells (most cars are 4S or less)
HV 110 airplane/heli ESC
GY 502 Gyro
Futaba 9253 heli tail servo for steering
Neu 1515/3DF motor
Eagle Tree data aquisition equipment

Actually, there are more aircraft components on this car than car components. Hmm, isn't it that way with full scale land speed record cars?

Matt
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