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Old 07-16-2007, 07:34 AM   #136
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Hey your back! Nice one.

Looks like i'll be coming over the pond to attend the comp. Best of luck with the testing and see you on 28th

Cheers
Youre coming? cool. That plane ticket must have cost a mint. How much was it?
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Old 07-16-2007, 09:28 AM   #137
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Youre coming? cool. That plane ticket must have cost a mint. How much was it?
Nada. I got enough air miles to take the whole family 1st class if I wanted.

Check out the latest mod to my radio gear. I will bring the whole setup to the comp. If you have a spektrum set you can use it.

http://ziggy12345-myspeedattemptcar.blogspot.com/

Cheers
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Old 07-24-2007, 07:05 PM   #138
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Default Video "X2" Update: Testing at Houston Raceway drag strip

Video and many more pics here











Video and many more pics here

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.
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Old 07-24-2007, 07:34 PM   #139
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try using hard oval tires because the tm's even failed at 60 mph
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Old 07-24-2007, 07:36 PM   #140
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great videos...is it too late to switch to rear drive & a body that creates some mechanical down force to keep those tires from failing when they break loose?
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Old 07-24-2007, 08:12 PM   #141
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try using hard oval tires because the tm's even failed at 60 mph
The tires I need to use with my car are 3.25" in diameter. I think oval tires are 2.2" in diameter so they're too small.
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Old 07-24-2007, 08:43 PM   #142
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great videos...is it too late to switch to rear drive & a body that creates some mechanical down force to keep those tires from failing when they break loose?
Basically, I first designed the car to be rear wheel drive. I designed a body that would create downforce at high speed. But with testing, I discovered that running the car rear wheel drive caused major instability. The back end would always want to come around and fishtail at any speed. So I tried everything in the book to fix this problem and I still had instability. I almost gave up and decided to run the car backwards. I tried it and it worked really really well. The car would track in a straight line and was super stable. So basically the car is a front wheel drive, rear steer car.
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Old 07-24-2007, 08:46 PM   #143
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Are you going to make the front more aerodynamic? Like you did with your original design.
Have you also tried glueing the foam to the rim?
Im really excited for you. This is very cool thread, and alot of work thats gone into this. Great job!
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Old 07-24-2007, 09:03 PM   #144
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Are you going to make the front more aerodynamic? Like you did with your original design.
Have you also tried glueing the foam to the rim?
Im really excited for you. This is very cool thread, and alot of work thats gone into this. Great job!
I am going to make the front end more aerodynamic. I already have a front fairing made I just didnt attach it to my car for these tests. This is what it looks like:



The next thing I am going to try is to minimize the "hopping" effect that the front end has under acceleration. I think this is what caused the tire failure. The tire would bounce up in the air for a split second and increase in RPM very quickly. This would cause huge forces on the tire and it would separate from the rim. If that doesn't work, I'll try to glue foam donuts onto the rim

Thanks for the compliment. I like desiging and testing something that no one else has done before.
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Old 07-25-2007, 01:40 AM   #145
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The tires I need to use with my car are 3.25" in diameter. I think oval tires are 2.2" in diameter so they're too small.

Im using 45 shore 1/8th tyres. They are 3" dia and a lot wider. With all the interest in speed runs why hasnt somebody come up with a tyre solution for us?
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Old 07-25-2007, 05:39 AM   #146
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Im using 45 shore 1/8th tyres. They are 3" dia and a lot wider. With all the interest in speed runs why hasnt somebody come up with a tyre solution for us?
I have those tires too. The problem is that I dont have the right adapter to use them on my car.
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Old 07-25-2007, 07:19 AM   #147
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Im using 45 shore 1/8th tyres. They are 3" dia and a lot wider. With all the interest in speed runs why hasnt somebody come up with a tyre solution for us?
Did you get your car fixed from your accident?
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Old 07-25-2007, 07:23 AM   #148
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Yup. All fixed and packed away to travel to Los Angeles tomorrow. The body shell was a bit of a tight fit in the case so I hope it survives the journey.

See you all at the diner for breakfast at 7am

Cheers
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Old 07-25-2007, 09:10 AM   #149
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Good luck guys and have fun
Look forward to the results and stories afterwards.
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Old 07-25-2007, 12:20 PM   #150
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I think it's awesome that some are coming from so far the this event...and working on so many exotic ideas.

I can't believe the cars I'm seeing tested have so much steering dual rate still in them - I'd figure you would want to be down to around 10% or less so the car could NOT turn sharper than about a 30 ft. circle just to take some of the sensitivity away on the straights.

FLIPPING the car around and making it FWD, although it could make steering really tricky (Cause REAR Steer requires about 20% of what a Ft. wheel steer car does), but if you get it dialed down and make it track straight...I'm thinking that should end a LOT of your other aero concerns from early tests.

A) it gives you the nose weight to keep the front end from lifting. (Maybe some type of fairly blunt nose body panel would be good just to keep the air directly off the front end)

Did you set the steering wheels with TOE out (or IN) to improve tracking at all? Or did you leave them as straight as possible for lower drag?

Also, did you reverse the CASTER angles when you turned the car around?

...can't wait to hear some of the results -

We'll be in Southern Calif - at the ENCINO VELODROME (bicycle velodrome) both Saturday and Sunday July 28-29 for our own event (of which normally Nic Case would also be running) - HOPEFULLY someone will keep us posted..and we can announce how things are going.

Any of you guys coming to So. Cal. this weekend for the WFRCC competition...if you are still around on Sunday - take the 40 mile drive up to ENCINO (just off the US101 and 405 freeways) and bring your SPEEDRUN cars by and show them off.
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