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Old 06-24-2007, 09:33 PM   #121
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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.
No, I'm not running a gyro. But at this point I am thinking about trying. Matt Shumaker is running one on his car and he swears by it. I am trying to fix this problem by chassis tuning/aerodynamics. If I cant remedy with this way, I'll see about getting a gyro.
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Old 06-24-2007, 10:17 PM   #122
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No, I'm not running a gyro. But at this point I am thinking about trying. Matt Shumaker is running one on his car and he swears by it. I am trying to fix this problem by chassis tuning/aerodynamics. If I cant remedy with this way, I'll see about getting a gyro.
..here might be a good place for your gyro setup should you choose to go that route...... www.runryder.com
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Old 06-24-2007, 10:39 PM   #123
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The steering issue is one of those I was trying to make with the shape of the body. The high angle nose will give (in my opinion) too much 'mid speed' steering, and I'd guess you would need to turn the steering rate down to about 10-15% or less. (Nice thing w/ the 3pk being able to set the button under the steering wheel to give MAX steering to turn around when needed.)

LOTS OF CASTER will help it stright line... The rear wing should be FLAT with large sides for straight line tracking stability , mounted LOW and behind the rear wheels...but make sure there is NO kick, drag in the flat part of the wing.

THAT radio range SUCKS - I'd think a 3pk w/ a PCM reciever should get you over 500-600 ft on 75, and maybe more on 27 band...but if you are flat on the ground - you may need to get 10 ft. or so up in the air.

In looking at your pic - something I'd do with what I see. FLATTEN The front nose (get rid of the slope), move the front body work back (less overhang to create leveraged downforce on the front wheels) Flatten the wing, it looks like it's on about a 6-8 degree angle.

LOWER the height of the wing - and move it LOW behind the rear wheels, with VERY LONG side dams, (at least 3 - 4 inches) with maybe a 1/16th in verticle wicker on the trailing edge.

I have a nice surface street I get to test my oval/velo cars on - and I only try to hit 55-60 on the street, because of footage/radio distance and the fact the street is nice asphalt, but very DIRTY and DUSTY so it's really easy to lose it and climb the curbing...

Running the radar gun using just 4 cell nimh w/ a 10.5 motor this car can easily run 50+ in a 300 ft section before I have to shut down HARD to keep it from running out of range...

SURFACE is way to dusty to do a full INSANE run - I tried my 5.5/LIPO and was only able to pull 1/4 throttle before it buzzes the tires in the dust.

When you get to go test...do you get to clean the surface? If so, can you clean it - and/or wash it...then SPRAY IT with 10 - 12 bottles of GRAPE SODA?

I had a question on the motor too: What is the expected RPM per VOLT value for the motor, What is the input voltage and what is the calculated RPM at speed? Also what size are the rear tires?
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Old 06-25-2007, 01:10 AM   #124
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The steering issue you have is due to the back suspension. Firstly a solid rear axle will only really work if the body is a lot longer. You will also need rear left and right suspention setup options as well as toe in, camber and agle change adjustments. All of these issues have been addressed in a kit car and thats whey I used a kit rear end for my car.

You are going to be pulling your hair out trying to solve the handeling issue. At the very least you will need a diff for the back.

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Old 06-25-2007, 03:13 AM   #125
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...I thought in his pics, he had the rear suspension still hooked up to a tplate type deal with the side shocks.

The front end is a typical ASSOCIATED Pan Car front end, which should be able to be made to work ok if the float is right - and the height is high enough to not let the chassis scrape the ground or tires.

As far as a DIFF'd rear end - if he can get the traction (CLEAN SURFACE w/ SPRAY of some SORT) and get both rear tires balaced equally (NO TWEAK) I would think it should launce fairly straight and run straight...but if the tires buzz - it's going to be GONE

I have some old SLOT CAR tire sauce that would give you an AWESOME hole shot - but if the surface isn't really clean you'd have STONES stuck to your tires within 5 feet....but if you can STICKY up the surface w/ some soda syrup and have it DUST FREE, then use a good foam tire traction compound (I like STICK-ET) you should get past the first 50-60 feet.

If you have the power, (AND YOU OBVIOUSLY DO) I'd go more toward HEAVY CASTER and TOE OUT (a little scrub) but this will make the front tires want to go STRAIGHT where TOE IN and LITTLE CASTER will make the car want to wander. Something I've wanted to try is heavy CAMBER too, but shave the front tires so they would be coned and ride flat //-----\\, I would also use TRAILING front axles...NOT centered. That will make the tire run on the rear most part of the front tire, taking steering sensitivity away as much as possible.

I do believe the weight of that motor deal is going to be hard to balance and hard to get sprung right for the rear pod...but SHOULD add to the rear traction....I would move as much of the rest of the weight as CLOSE to the front wheels as possible...

BUT Hey - this isn't my project - and it is FUN reading about it... THANKS for the continued reports...and photos
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Old 06-25-2007, 08:42 AM   #126
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Quote:
Originally Posted by SWTour View Post
The steering issue is one of those I was trying to make with the shape of the body. The high angle nose will give (in my opinion) too much 'mid speed' steering, and I'd guess you would need to turn the steering rate down to about 10-15% or less. (Nice thing w/ the 3pk being able to set the button under the steering wheel to give MAX steering to turn around when needed.)

LOTS OF CASTER will help it stright line... The rear wing should be FLAT with large sides for straight line tracking stability , mounted LOW and behind the rear wheels...but make sure there is NO kick, drag in the flat part of the wing.
I have been experimenting with exactly that. The RC10L3 manual says that the front suspension can go from 0-4 degrees of caster. Can I get more than this?

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Originally Posted by SWTour View Post
THAT radio range SUCKS - I'd think a 3pk w/ a PCM reciever should get you over 500-600 ft on 75, and maybe more on 27 band...but if you are flat on the ground - you may need to get 10 ft. or so up in the air.
Yes, only 400' range with that new 2.4 ghz 3PM is terrible. My 15 year old 2PK PCM is on the 27 band. I am thinking about going back to that radio. That one had much better range. Nic Case and I have been talking a lot and he says he has been testing the new Futaba 3PKS with the Futaba 2.4ghz module and receiver he can get almost 1/2 mile.

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In looking at your pic - something I'd do with what I see. FLATTEN The front nose (get rid of the slope), move the front body work back (less overhang to create leveraged downforce on the front wheels) Flatten the wing, it looks like it's on about a 6-8 degree angle.

LOWER the height of the wing - and move it LOW behind the rear wheels, with VERY LONG side dams, (at least 3 - 4 inches) with maybe a 1/16th in verticle wicker on the trailing edge.

I have a nice surface street I get to test my oval/velo cars on - and I only try to hit 55-60 on the street, because of footage/radio distance and the fact the street is nice asphalt, but very DIRTY and DUSTY so it's really easy to lose it and climb the curbing...

Running the radar gun using just 4 cell nimh w/ a 10.5 motor this car can easily run 50+ in a 300 ft section before I have to shut down HARD to keep it from running out of range...

SURFACE is way to dusty to do a full INSANE run - I tried my 5.5/LIPO and was only able to pull 1/4 throttle before it buzzes the tires in the dust.

When you get to go test...do you get to clean the surface? If so, can you clean it - and/or wash it...then SPRAY IT with 10 - 12 bottles of GRAPE SODA?
We dont get to clean the surface. It is a best buy parking lot and we usually just show up and run.

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I had a question on the motor too: What is the expected RPM per VOLT value for the motor, What is the input voltage and what is the calculated RPM at speed? Also what size are the rear tires?
The motor is a NEU 2215/3Y. It has a KV of 480. My design setup is will eventually be 12s (44V). Calculated RPM at that speed is about 20,000 rpm. The rear tires are 3.25" in diameter. Here are the calculations that I have done on a spreadsheet I setup:


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Old 06-25-2007, 08:43 AM   #127
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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):

I have talked to Matt, several times, even bought a motor from him. Small world, when it comes to RC.
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Old 06-25-2007, 10:19 AM   #128
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I have talked to Matt, several times, even bought a motor from him. Small world, when it comes to RC.
Yea, hes a great guy. He can make numerous 100+mph runs in one day. He has more wheel time with high speed cars than anyone.
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Old 06-25-2007, 10:40 AM   #129
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My Futaba 3PK with spektrum HRS has a range of around 1/2 mile. I want to try the 40mhz system with 12 cells, this might be even better

For the Futaba 2.4 ghz system. Are you sure its not in FRENCH mode? There is a switch on it that says France / rest of the world

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Old 06-25-2007, 11:12 AM   #130
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My Futaba 3PK with spektrum HRS has a range of around 1/2 mile. I want to try the 40mhz system with 12 cells, this might be even better

For the Futaba 2.4 ghz system. Are you sure its not in FRENCH mode? There is a switch on it that says France / rest of the world

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Is the switch on the transmitter or receiver?
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Old 06-25-2007, 11:17 AM   #131
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I think its on the TX. I saw a pic of it on a forum somewhere. I thik in france they cant transmit above 10milliwatts or something

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Old 06-25-2007, 11:50 AM   #132
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I think its on the TX. I saw a pic of it on a forum somewhere. I thik in france they cant transmit above 10milliwatts or something

Cheers
Oh, thats on the 3PKS version of the module. I don't have this radio:



I have this one. It doesn't have a switch for France/everyone else:

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Old 06-25-2007, 07:39 PM   #133
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Good info B4 - on the CASTER issue, we use to have SHIMS that went under the OLDER style ASSOC front ends...If you add something like these (They were wedge shaped) or space up the front of the lower control arm you can get MORE caster... AND/OR you can go with an AFTERMARKET Caster block made for the L4 style cars...from like IRS, or CRC or DARKSIDE or RACEWAY MFG. or someone like that.
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Old 07-15-2007, 08:21 PM   #134
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Default Testing today - great success!



John Stranahan sweeping off the testing surface

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 about 60 mph (about 1/4 throttle) with no stability problems. John provided a radar gun to track our speeds. We placed it on a tripod pointing at the racecourse. The readings from the radar gun were about 50 mph, but my Venom speed meter was reading 60mph. I think I was achieving my highest speed outside of the radar guns range. 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. Video of that here.

More info and details here
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Old 07-16-2007, 12:58 AM   #135
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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
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