X2 Testing (8-3-08). Another blowout.

First set of tires tested

Tires worn down to their minimum diameter after only 5 runs

Second set of tires exploded at 72 mph

Tire carnage all over the track

Click on video above then click on "watch in high quality"

In this testing session I tried 2 sets of tires. The first set of tires had foam cut from a large piece of stock foam. Then I glued the foam onto the custom aluminum rims that my father machined. Then I trued down the diameter of the foam from 4.5 inch to 3.5 inches. The second set of tires are based on the stock foam tires that come in the OFNA Ultra GTP kit. The only thing I did was true down the diameter from 4 inches to 3.5 inches. Then I modified the center of the rim to accept the 1/10th scale clamp style hub.

I first tested the aluminum tires. I ran these tires for about 5 passes. After each pass I would check the diameter of the tire. It was apparent that the foam I used for the aluminum rims was wearing out very fast. Sunny said that as the X2 passed by, he could see tire dust billowing from the sides of the car. Within 5 runs the tire diameter went from 3.5" to about 3.25". The minimum diameter I can run is about 3.25" before the chassis starts to hit the ground. These tires worked very well and held together for a pass with a max speed of about 70 mph. The problem that I am seeing is that on that 70 mph pass, I was using 100% throttle. With 30 V at a KV of 480 that is an rpm of 14440. That should be a speed of 110mph. There is obviously serious wheel spin.

The second set started out very well. But after I made more passes and increasing throttle, the tires exploded. The same thing happened as with the first set, I was giving the X2 full throttle and the tires were spinning at a much higher rate than what the car was traveling.

It looks like I am going to put the X2 on standby for now. I am going to concentrate on the X3 for the International Speed Competition in October. I am working on getting a 12s battery setup. The X3 has been performing very well and I am going to be shooting for 100mph on the 12s setup. Check back for details on the X3.

X2 is back

I have been working on some changes for the X2 while I have been testing the X3. This past Saturday, I tested some new wheels. These wheels were taken from the OFNA Ultra GTP and I modified them to accept 1/10 scale clamping hubs. Then I trued the tires down to 3.5" in diameter from 4".

Here are some videos of the X2 doing some low speed passes from this Saturdays testing:




Some people have mentioned to me the reason why I have been blowing up tires is from all the sprung weight of the motor within the suspension. I do agree with this. But I have to wonder if the problem is still the design of the car, or a problem with the tires. If you take a look at Nic Case's prototype from last year, you can see that neither the front end or rear end has suspension:


Nic was supposedly able to reach 130mph with this car and his wheels are half the diameter of my tires. So it seems like the tires aren't the limiting factor in these high speed r/c cars. I will still be working on the X2 as my main car for the high speed event, but the X3 will be a backup. I will be doing some more testing with different tires and I will post my progress here.

The International R/C Speed Challenge - presented by Castle

International R/C Speed Challenge-Presented by Castle
Is happening this year Oct 4th @ the Birthplace of Nascar
We will use ROSSA rules & DUAL Optical Speed traps.
There are plenty of classes for everyone
How Fast is your car? – Prove it to the World
Rockingham Dragway is a First Class facility.- Billy Weeks is the race director
*******Extreme R/C & R/C Driver will be covering the event!*******
---other magazines welcome---

The "International Speed Cup" is for the over-all fastest speed in the world! It’s a perpetual Award---(Similar to a Stanley Cup)------ Starting at the UK event ------ and if us Americans can TOP the Britt's speed------ the "International Speed Cup" comes to the United States!---
only the fastest driver in the world will ever possess the “Cup”

There will be a 100 mph club -----You will receive a special embroidered hat for everyone that breaks the century mark!

This event qualifies for the Guinness Book of World Records.

Be a part of History; feel the need--- the NEED FOR SPEED!

Entry Form

R/C Speed Challenge 2008 Officially announced! October 4th at Rockinham N.C. - Sponsored by Castle Creations

The 2008 R/C Speed Challenge has been officially announced. It will be hosted at Rockingham Dragway in North Carolina October 4th 2008. It is sponsored by Castle Creations. Click the Castle logo above to get more information about the event. Details are still being ironed out, but the event will happen this year.

This is what Nic Case said about the event:

Hi Guys

Yes-- the cat is out of the bag.......We will have a speed run in the United States-- on Oct 4th!
We will use ROSSA rules & an Optical Speed trap. This is going to be a blast!
I understand North Carolina is very nice in Oct.
We have a lot of support from sponsors. Thanks to Billy Weeks for handling the race director/Promoter duties...

Special thanks to Tony Lovering (aka AJ/ziggy 12345) for having this site & being the founder of ROSSA...!

R/C Driver has committed to a 2 page article
Extreme R/C is interested

We will have an "International Cup" for the over-all fastest speed ---- Starting at the UK event –
-- and if us Americans can beat the Britt's speed--------- the "International Cup" comes to the USA!

There will be a 100 mph club ------- A special embroidered hat for everyone that breaks the century mark.

We are in the process of getting the details for the "Flyer"------ so, stay tuned.

Speed is Cool
N

More information can be found here.

Testing results from 7-12-08. 83 mph. Motor problems

What the motor should look like

After doing some high speed runs. The motor endbell has slid off.

This post is a week late since I've been pretty busy lately. But I wasn't able to get any faster than 83mph. I made some changes since the last testing session. I removed all the data logging equipment, I modified the body and I removed the heavy stainless steel gear and replaced it with a lightweight delrin gear.

After doing the last pass of the test session, I noticed the power of the motor decreasing. I removed the body and I took a look at the motor and I noticed the end of the can was sliding off. It came loose during the runs. You can see this in the second picture of the motor. It has come off about 5mm from where it should be. Neu Motors has addressed this problem with their newer motors and has secured the endbell with screws like the motor below (the pic is a Neu 1515 but I will need this on my 2215):


I am going to have to send the motor back to Neu to get it repaired. I think this is the problem with not being able to get a higher speed. I should be able to reach at least 90 mph on 8s.