b4maz

iTrader: (8)

Thanks for the support.

The body is all done, but I am waiting to get the correct mounting hardware. I am using button head screws to mount the fiberglass body to the chassis. I am also waiting for a shipment of foam to come in so I can cutout the rear aerodynamic fairing/diffuser. Once the fairing is done, then I can attach the vertical stabilizers. Thats when all the aerodynamic components will be done and I can start doing some real high speed runs. I also have a Futaba 2.4ghz system on order and should be in next week.

b4maz

iTrader: (8)

My friend, Matt Shumaker, is also working on an Insane Speed Run car. He has done a TON of testing (multiple 100+ mph runs in one day), and this morning he said this about these high speed cars:

Matt is at about 4.5 hp. I am using a Neu 2215 on 12s. If I pull 130 amps, I will be up at 5300 watts, or about 7 hp. I wonder if there is indeed too much power? I am not going to let this distract me from my testing. I may find a way to control all this power.

b4maz

iTrader: (8)

Here are the clouds rolling in:



This is John's car checking out the running surface:



This past weekend was pretty much rained out. John and I did get to go out to the testing area (Best Buy parking lot). We got a couple runs in but after 5 min it started to pour. This weekend looks promising. Much better for testing.

I got my new Futaba 3PM 2.4ghz transmitter installed. I plugged everything in but now I am having problems with the throttle again. It doesn't sense neutral. I have to hold the brake to keep the car from rolling. I am trying to set it up so it doesn't do this. I also installed much stiffer side springs on the suspension. I was using the silver 8lb/in springs before, now I am using the copper 16lb/in springs. This drastically improved the way the car handles. With the added weight of the extra battery, the car would want to keep swaying back and forth and never go in a straight line. With the stiffer springs, this has almost disappeared.

Taylorm

...we want video...........

b4maz

iTrader: (8)

lol, this is the only video I got so far:

http://fastrc.blogspot.com/2007/06/v...run-of-x2.html

There will be more videos to come. Hold your horses.

speedxl

B4maz the stiffer the spring rate the more stable it will be( softer unstable ).

Also note driving the car without the body will make it drive awkard! I would bet it might feel just like a 1/12th scale 6cell mod pancar without the body !!

Crazy fast, but very unstable to drive because of no areo downforce.




Also to your friend with the TC3 the car might be suffering from the torque steer due to it being a shaft car. That is one of the reason's associated scrapped the drive shaft for belt. Once you start putting more power thru the drive train than what a 19t produce's the problem is amplified.

He also needs to go up on spring rates also, he has to much preload on the springs to get clearance. He also might have spring bind, which causes erratic handling.
Those tires he is using ( look like oval radials )need heat in them to work, thats why they are used on high bank oval tracks to reduce traction "rolling resistance " instead of making grip. They have a very stiff side wall and dont shred..
What he needs is a tire that well give more forward bite " acceleration traction". Foam tires may be the only thing that will (may up to ? speed) work. Thats what all the drag racers use, they don't use radial at all!!!

You might want to add some VHT to the surface for the length of your test track. I think they held the speed run on a drag strip with tons of VHT and rubber laid down from the full scale cars. Dirty parking lots dont help unless you blow it off and prepare it a little. The Vht helps to keep the sand from being a problem.

Just trying to help, your car and John S's car are really nice hotrods. Even though I am a hard core racer I really do enjoy reading these threads because this is what this hobby is about " tinkering " building some cool fast r/c cars.

I really find this and John's thread very infromative to read keep up the good work!

chris72983

iTrader: (3)

That is one huge motor

b4maz

iTrader: (8)

All the guys working on speed run cars now are working with very high horsepower. We are learning that we are going to need all the traction we can get. Nic Case, Matt Shumaker and I have talked about this at length. Its basically coming down to a drag race and not really a top speed race because of the distance of 1/4 mile we have to work with.

b4maz

iTrader: (8)

During my first couple of test runs, I had a lot of difficulty getting the car to track straight. It was tough to get on the throttle and get the car up to speed without the car getting very squirrelly. I decided to lengthen the chassis and make it out of carbon fiber instead of G10. The carbon fiber has much stiffer properties than the G10 and it seems like the chassis doesn't want to warp as it did with the G10. This lets the suspension do its job.




Here is the new stretched carbon fiber chassis next to the old G10 chassis. The new one is 50mm longer in the wheelbase.

chris72983

iTrader: (3)

The carbon fiber looks alot better, and is better suited for the job anyway. Just curious on your tracking problem, are you running a gyro on the steering. If not this will help this problem alot, I have done some testing with this before, and it works.

chris72983

iTrader: (3)

The carbon fiber looks alot better, and is better suited for the job anyway. Just curious on your tracking problem, are you running a gyro on the steering. If not this will help this problem alot, I have done some testing with this before, and it works.

SWTour

iTrader: (9)

...I hope you have better luck w/ the GYRO than I had some 15+ years ago.

I tried one on a really slippery OVAL track with a car we were NOT allowed to run a wing or spoiler on. This thing was AWESOME in the corners at self correcting and keeping me from spinning...but MAN did it SUCK on the straights.

It would "HUNT" on the straights - making the car swerve back and forth quickly...like it was nervous.

Finding the PERFECT balance point was difficult with the chassis sitting so low. And finding the perfect mounting location almost needed to drop below the chassis (Which I had thought about raising the chassis high enough, and cutting it so the GYRO hung down through the chassis.) After 2 1/2 months - I gave up trying while I still had HAIR.

chris72983

iTrader: (3)

Gyro technology has changed a lot in the last 15 years. He shouldnt have any problems with it at all. There are several people running these insane speed run cars, that are running them.

b4maz

iTrader: (8)

My friend Matt Shumaker is running a high end Futaba gyro and he swears by it. In this picture you can see the gyro (the little silver thing way in the front):

b4maz

iTrader: (8)

This is a crude test prototype of the body and wing. The body is made from fiberglass. The body attaches to the chassis with button head screws on the sides. The wing is an inverted NACA 9509 airfoil section. I made this wing in college for wind tunnel testing.





Here is a link to the video

The weather held out for John and I to do some testing. There are a couple changes I made since the first ground test. I made a longer chassis out of carbon fiber instead of G10. The G10 chassis was my prototype chassis. I used it to place my components and see if the layout was correct. I found that the car has too much over steer. I have been trying to remedy this problem with much stiffer springs in front. This did help a bit, but I found that carbon fiber has a much better resistance to a torsional load than G10. This means that the chassis bends less and the suspension can do its job more effectively.

The tests didn't prove as promising as I would have liked. I still cannot get my speed up above 30 mph. The steering is way too sensitive and it makes the car spin out. It feels like significant over steer. You can see this in the video. Right at the end my car wanders towards John and I almost hit him.

My new Futaba 3PM 2.4GHZ radio does not have nearly as much range as my very old Futaba 3PK PCM system. The 3PM gave me only about 400' of range. Very disappointing. I was hoping for much more.

After my disappointing testing on Saturday, I also didn't have a very good day today (Sunday). I was testing different front camber/caster settings to help remedy the over steer problem. I go and test a camber change, stop the car, make another camber adjustment, then I go to turn the car on and now my speed control will not arm my motor. I am not sure what the problem is at all. I tried to recalibrate the radio, I tried my old radio and I still cant get it to arm the motor. So at this point I am out of commission until I fix the speed control. Joe Ford, any suggestions?