Pictures of the X2 progress in chronological order

Tuesday, July 24, 2007

Video "X2" Update: Testing at Houston Raceway drag strip

Here is some video of when we first arrived at the drag strip. I start by slowly increasing my speeds on each pass. On the last pass you can hear buzzing as the car goes by. The buzzing sound is caused by the wheels becoming unbalanced as they lose more and more foam. In the pictures below you can see tire chunking. Top speed in this video was about 70 mph. Another thing to point out is how quiet the car is. Since this car has no gears or transmission, the only thing you really hear is the motor whine as the brakes are applied or if the chassis scrapes the ground. On faster runs all you can hear is the disturbed air as the car blows by. Around 3:10 is the fastest pass.
"X2" ready to get started.
I made a new Lexan body to conform with the car driving backwards. On my previous test runs I found out that driving with the motor in front and drive wheels in front greatly improved stability. On the left is my old Futaba 1024 27 mhz PCM transmitter that yielded about 4x better range than my brand new Futaba 2.4 ghz 3PM.
One set of tires blown up.
Another set of tires blown up.
Tire carnage from a day of high speed testing. I went through 4 sets of tires today. All had the same problem of self destructing. The adhesive between the rim and tire could not hold everything together.
My max speed out of these tests was about 70-80mph. We were also using a radar gun to measure speed and it closely matched my on-board speed meter.

I was able to get permission to test at the Houston Raceway. Its a full scale 1/4 mile drag strip on the east side of Houston in Baytown Texas. For this test I designed a new body out of Lexan. I was running 8s Li-Po 3300 mah Thunder Power batteries and a NEU 2215/3Y motor direct drive. I was not getting any range with my Futaba 2.4 ghz 3PM transmitter (only 100ft) so I went back and used my very old Futaba 27 mhz 1024 PCM transmitter. I was able to get almost 900ft of range with this old controller.

The results of my testing showed that around 70-80mph my TMRC drag racing tires would catastrophically fail. I would hear a very loud "crack" or "pop" as they would explode leaving foam all over the track. The car was not damaged in any way and was still very controllable even after tire failure.

After testing, I checked TMRC's website and it says that these tires have gone 107mph on nitro drag cars. I called and they said that other racers have encountered the same problem I have. They basically said that the tires might be hopping off the ground and free-wheeling for a split second. This causes the RPM's to go way up and the tires can fly apart. I will have to go back and try different spring and dampening combinations to minimize my wheel hop.

Sunday, July 15, 2007

Testing today - great success!

Equipment all setup at the testing site
John Stranahan sweeping off the test area.
Its ugly but functional. The body and aerodynamic pieces are prototypes.
Its ugly but functional. The body and aerodynamic pieces are prototypes.

Today was a great testing day. I made awesome progress. Before today, I was having a ton a problems keeping the car pointed straight ahead. I could drive the car up to about 40 mph, then if I gave the car any kind of steering input, the car would fishtail and spin out. To fix the problem I tried changing camber/caster, spring weights, shock oil weights...anything. I was totally stuck then I got an idea. Run the car backwards. Run the car with the motor/drive wheels in the front and the steering in the back. I tried it and it worked great! Today I was able to get up to 60 mph (about 1/4 throttle) with no stability problems. I actually had too much straight line stability because I couldn't steer the car above 40mph. This issue has more to do with the sizing of the vertical stabilizers. I can use smaller ones for my next tests.

Acceleration was phenomenal and during braking the car would stay in a straight line without any effort. Today marks a huge milestone for my project "X2". I couldn't go any faster today because of the size of the area that we have to work with. Its only about 100 yards to work with. To get my car up to its full potential I need to find a much larger, flatter surface to test. Hopefully next weekend I'll be able to test at a much larger area.

The only problem for today is not being able to capture video of my car in action. We had technical difficulties with my camera and I wasn't able capture video with my car. But I did get a catch a close call with John's car. He was making a high speed pass and his car almost hit my full size car:

Saturday, July 14, 2007

WFRCCC 2007 Rules

WFRCCC entry form

WFRCCC 2007 Rules

1. Wheel-driven vehicles only. Vehicles powered by thrust (jet, rocket, propeller, etc.) are not allowed. Turbine power is allowed only if the turbine is used to drive the wheels, not for thrust.

2. Vehicles may be powered by engine(s) or motor(s) of any number and configuration.

3. Vehicles may be any weight, with any chassis configuration and any number of wheels—but the completed vehicle may not exceed 40 inches (1016mm) in length.

4. All vehicles must use commercially available radio gear with a functioning fail-safe system set to apply full brake in the event of signal loss or interference.

5. Vehicles are not required to look like any type of "real" car or truck, but all entries must have some type of 3-dimensional "cockpit area" with windows (clear or painted). It's OK if your car looks like a space ship as long as it appears to have a place for a guy to sit.

6. No sacrificial power systems. Motors or power systems that, by design, are inoperable after a single run are not permitted.

7. Drivers must operate their vehicles from a fixed position. Chase cars are not permitted.

8. Drivers or teams may enter as many cars as they like.

9. For a speed record to count, the vehicle must make a second run and achieve a speed that is within 2% of the record speed. The second run can be made at any point during the event, the runs do not have to be back-to-back.

Entrants will be divided into three classes: Manufacturer Team, Independent Team and Individual.

MANUFACTURER TEAM: entries fielded by RC companies will run in the Manufacturer Team class.

INDEPENDANT TEAM: if the entered vehicle is the collaboration of three or more individuals operating without the support of a manufacturer, it will run in the Independent Team class. High school shop teams, university engineering departments, RC clubs ... this is your class!

INDIVIDUAL: any vehicle entered by a single person will run in the Individual class.

Each vehicle will be given three attempts to make its fastest run. The vehicle with the absolute highest peak speed will be declared the overall winner, and separate awards will be given to the fastest vehicles in the Manufacturer, Independent and Individual classes.

Some questions I've received:

What is the length of the track? It's a full-scale 1/4 mile drag strip. Use as much of the track as you like.

What’s the run up and slow down length See above. You'll have the same shut-down area as a full-size drag car.

Do we need to do 2 runs in either direction? Covered in rules posted above.

Are they one after the other or do you get a period to prepare the car for the 2nd run? Once you're up, you can make more than one run if you want, but once you take the car off the track, it will be the next driver's turn

What happens if you can’t make the 2nd run? Skip your turn, then go in the next opening. If the event runs like it did last year, we'll be following a simple "go when you're ready" system. If you're not ready to go, the next person who IS ready will go. If you're ready after him, you can take the track. It's pretty laid back, we want everyone to get all the track time they can and have a good time.

What constitutes a manufactures team? See post above.

What frequencies can we use for radio equipment? (We don’t have the same ones in Europe and don’t want to get there and have to buy new equipment) Anything you bring should be fine. All radios will be off except for the driver's on the track. I'll bring a spare radio and receiver just in case any driver has an issue.

Are we allowed to modify radio equipment? The rules state "All vehicles must use commercially available radio gear with a functioning fail-safe system set to apply full brake in the event of signal loss or interference." Personal comfort mods (aftermarket wheel or grip, that sort of thing) are ok, but electronic mods are not allowed. I changed my mind, after seeing a few of the radio-mod posts. As long as your "base" radio is an available hobby item, then it's all good.

Are we allowed to boost the output of the transmitter (2.4 ghz is no licensed up to 100 mw but you can get a license for more and boost the signal to 5 watts and get 5 miles range. Can I use this equipment in the USA?) Sorry, need to use out-of-the-box gear.

Can you use other digital frequencies? 900 mhz, 1.2 ghz, 1.4 ghz….. up to 5.8 ghz. These are not available commercially but people are looking at these systems (Me!)
I'll allow this as long as there's no performance advantage.

Wednesday, July 11, 2007

Speed control out for repair

Here is the "X2" currently without the speedo
Becky and I just married

I haven't been working on my car for the past 2 weeks. There are a couple reasons for that. One, I got married on July 6th and two, my HV-110 doesn't want to arm my motor. Even if my car was working, these past 2 weeks have been so busy I wouldn't have had much time to do testing anyways. The HV-110 is in the hands of Castle Creations now and hopefully I can receive a new HV-110 soon since it is still under warranty.