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Insane Speed Run car almost complete

Insane Speed Run car almost complete

Old 06-01-2007, 12:30 AM
  #31  
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What motor are you using nick? is it the 2215/3Y @ 480v/rev? or is it the 2.5Y or maybe the 2Y?

Cheers
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Old 06-01-2007, 01:45 AM
  #32  
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Just judging by the photo where it is sitting on the table it is sitting too low. And the break in the body is also a bad choice. You will need some type of downforce on the rear. 1/4 mile seems long but reaching the speeds you are attempting you are going to have to get there in a hurry. Its not going to be a ease into the throttle type thing like the do on the flats. You should take the radius you have on the tail section and run it all the way to the nose, a smooth continuous line and put some sort of airfoil on top of the vertical stabilizers you have on the rear. I would imagine a flat piece set at 2-3 degrees would even be enough.
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Old 06-01-2007, 02:38 AM
  #33  
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Originally Posted by PROMODVETTE
Just judging by the photo where it is sitting on the table it is sitting too low. And the break in the body is also a bad choice. You will need some type of downforce on the rear. 1/4 mile seems long but reaching the speeds you are attempting you are going to have to get there in a hurry. Its not going to be a ease into the throttle type thing like the do on the flats. You should take the radius you have on the tail section and run it all the way to the nose, a smooth continuous line and put some sort of airfoil on top of the vertical stabilizers you have on the rear. I would imagine a flat piece set at 2-3 degrees would even be enough.
You see Nick! Instead of spending all those months on design and testing you should have just guessed what to do!!
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Old 06-01-2007, 04:39 AM
  #34  
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Originally Posted by ziggy12345
These are the soft drag wheels and tyres you told me about right? I thought they might be a bit soft.

Parradoxically the tyres will go faster when they are on the ground. On the bench they are subjected to the same force all the way around and and they stretch untill failure. On the road the weight of the car depresses the tyre at the bottom and this keeps it together for higher revs.

I have some 1/8th tyres coming that are 45 shore. They are good for about 140mph. I am looking at covering them with a steel belted rubber skin that will keep them together for over 200mph.

How are you measureing the RPM? Are you sure it was only 15k?

Cheers
I wasn't measuring RPM directly. I was just using the KV of the motor (480) multiply that by the number of volts of an 8s pack (8 x 3.7v = 29.6v x 480 = 14,400) so its about 14k-15k rpms.
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Old 06-01-2007, 04:40 AM
  #35  
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Originally Posted by ziggy12345
What motor are you using nick? is it the 2215/3Y @ 480v/rev? or is it the 2.5Y or maybe the 2Y?

Cheers
Yes, its the 2215/3Y @480Kv
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Old 06-01-2007, 04:53 AM
  #36  
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Originally Posted by ziggy12345
These are the soft drag wheels and tyres you told me about right? I thought they might be a bit soft.

Parradoxically the tyres will go faster when they are on the ground. On the bench they are subjected to the same force all the way around and and they stretch untill failure. On the road the weight of the car depresses the tyre at the bottom and this keeps it together for higher revs.

I have some 1/8th tyres coming that are 45 shore. They are good for about 140mph. I am looking at covering them with a steel belted rubber skin that will keep them together for over 200mph.

How are you measureing the RPM? Are you sure it was only 15k?

Cheers
There are 2 things that are causing this failure. The huge amount of sidewall (the tire is very thick, i would say almost a half inch) and these tires are super soft. I going to try to see if there is a harder compound tire or a way to increase the diameter of the rim but maintaining the outside diameter to be the same.
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Old 06-01-2007, 05:02 AM
  #37  
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Originally Posted by Big B
After seeing the vid of those Foam tires you may want to go with Rubber, they will flex alot more. This is just an idea but in almost situation the batts on a 1/12th scale are as far back as they can go to help with rear taction, I don't know if you have tried or can with your design, but you migh want to look at sliding that stickpack on top to the far end of the lipo's. Or since from the pics it looks like there is a shock in the way, make a saddle pack to go up there, I am sure you could hold it down with some good servo tape.
I wouldn't mind testing some rubber tires that are 3.25" in diameter, but I cant seem to find anyone that makes them. If anyone knows who makes a rubber tire 3.25" in diameter, let me know.
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Old 06-01-2007, 06:23 AM
  #38  
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You can try this place

http://www.blickle.de/index.php?l=e-...d0a06042a22d55

Or these in the USA

www.servicecaster.com.

I will try the 1/8th 45 shore foam tyres. You might want to try them as they are a lot wider than yours so give more grip but still think they will fail at 130 or so. We shall see
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Old 06-01-2007, 09:50 AM
  #39  
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Originally Posted by b4maz


Well, first bench test was just done. I hooked up my 2 Thunder Power 4s packs in series to get 8s (around 30v) which gives me about 15K rpm. I free wheeled to check tire growth and how the tires would hold up. As you can see... not too good. I have a video of the failure here: http://fastrc.blogspot.com/2007/05/first-test.html
You can't alway's go by a bench test with tires with no load on them, sure you can blow off any tire, foam or rubber doing a bench test like that with no load to the wheels. I would try a test run out side so you have load on the wheels. I'm pretty sure that the tires wouldn't fail under load, with load on the wheels you will get different results. With the weight of that motor on the rear wheels your tires will not expand as big under load. You should complete building up the car, Then take it out for testing and see where you are at and then make final adjustments from there. Then if the tires do fail from there then that's when you start to try and reslove that issue then go to plan B. Since it's home built try to make extra spare parts too or a spare car, going that fast anything can happen. Good Luck and I hope all work's out for you. Take Care...

Last edited by trjracing; 06-01-2007 at 10:13 AM.
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Old 06-01-2007, 11:26 AM
  #40  
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Originally Posted by ziggy12345
You see Nick! Instead of spending all those months on design and testing you should have just guessed what to do!!
You can do all the design and testing you want. It makes it look nice and professional so people say ooooh ahhhhh this guy must be smart! But the fact is a nice looking design on the computer is a totally different design on the track.
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Old 06-01-2007, 01:35 PM
  #41  
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Originally Posted by PROMODVETTE
You can do all the design and testing you want. It makes it look nice and professional so people say ooooh ahhhhh this guy must be smart! But the fact is a nice looking design on the computer is a totally different design on the track.
LOL, but doing all that design and analysis is fun for me. Most guys like building their cars more than racing them, its all part of the hobby. I've always wanted to design something from scratch and I had the chance. It was fun. I also enjoy the testing I am working on now. To each his own!
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Old 06-01-2007, 02:31 PM
  #42  
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...you could try building some foam over foam CAPPED tires, with a layer of Strapping type tape inbetween the foam laminations. The strapping tape will help reduce some of the growing.

In doing this, you could use something like a 45-50 shore base foam with a softer 30-32 over the top for bite.

I don't know what the HIGH SPEED Velo CAPPED tires use to keep them from growing, but the NET style capped oval tires use to have what looked like a strapping tape belt glued in.
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Old 06-02-2007, 12:36 AM
  #43  
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The outer cover needs to be steel or nylon belted to stop the tyre growth. A rubber covering will expand the same as the foam.
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Old 06-02-2007, 07:02 AM
  #44  
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where did you get solidworks from?
i can't find it anywhere.
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Old 06-02-2007, 07:25 AM
  #45  
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http://www.solidworks.com/pages/comp...Worldwide.html or "other sources" if your into that king of thing.......
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