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Old 01-06-2007, 09:11 AM   #796
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Mathijs-Thanks for the tips and the discussion of spur gears. I only use brakes on my two hairpins. These brushless motors don't really brake that hard. I would hate to loose that ability. I can go back to 48 pitch if I strip a gear.

I have noticed that tire scrub. If I cut that section of the wheel arch away, I will loose valuable support of the rear wing. The fact that the scrub is black and has not worn the paint off much indicates I only get occasional contact. Probably when I am off line on the straight. The only solution for me would be to raise the rear of the body. I have used heat on my front arches, but they don't come out very nice. I can go up one notch on my rear body posts.
I understand about the rear body panel and have seen that discussed on McAllisters web site. I think it's up for debate. I have tried it both ways without noticeable change. I decided to leave it in place to support the side dams that are aft of the wheel and low on the body. I have good evidence that these side dams are important to straight line stability and poor evidence that cutting the rear of the body away helps anything. I left that section on for strength. Now if I had a venturi under the car and a rear diffuser then I would agree that cutting it away would help things.

Maybe some of you oval guys could tell me your preference on this rear body panel. It is much easier to see this kind of aerodynamic aid on an oval lap time sheet after an experiment.

Panhard Bar
"An additional note for the linguistically inclined: the word panhard is properly pronounced 'pannard' but most people pronounce it as it's written. If in any doubt, I recommend you say 'track rod' and if they look at you funny, explain what you mean, then smile knowingly when they say 'oh, you mean a pan-hard rod!'."

The Nascar guys call it a track bar. I thought of putting a hole and through the rear window adjustment. Just kidding.


John

Last edited by John Stranahan; 01-06-2007 at 09:35 AM.
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Old 01-06-2007, 02:30 PM   #797
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My experience is that when you leave the back panel on the body, the windflow underneath the body "loads up". It just adds drag, and decreases downforce.
Back 2 back testing might reveal what's best.
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Old 01-06-2007, 03:07 PM   #798
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Quote:
Originally Posted by DPowell
Thanks for the props. The replacement "L" chassis will be available shortly. I'm planning to offer a chassis brace also. With the chassis, chassis brace and the top and bottom plates that we already offer, you can build a wide "L" by converting a 1/12, a 10L3T or completely from scratch using the parts of your choice.
alright i'm ready... christmas is over, the kids got their stuff, and i have been holding out to buy myself a present this year...
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Old 01-06-2007, 03:48 PM   #799
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Mathijs-I'll assume then that you did a back to back tests. I'll chop that sucker out at a convenient time during qualifiers. I find that a lot of RC stuff is conjecture. I don't find a lot of full size race cars chopped out like that. I think it probably disturbs the high speed airflow under the car to do so. My other Peugeot body is chopped out. Everything at the back is quite flimsy as a result. Now how do you know you are not letting out the Vacuum (so to speak) rather than damming up the airflow when you chop the rear out like that.


3-link Track Report, vs Wide Pantoura
Track somewhat cleaner than yesterday still a few damp spots. Traction Medium

I ran the two cars back to back again today with the same setups and motors that I used yesterday. There was a bit more traction. Both cars were equally fast on the straight now whereas the 3-link was faster yesterday. The Wide Pantoura has the 3.5 motor the 3-link a 4.5. I think the 3-link car will go faster with the same motor due to better forward traction at speed over the bumps.

I had more cornering traction more forward traction and made fewer mistakes with the 3 link car. I ran it first this time. I ran it second yesterday. The 3 link car has more turn in than the wide car in spite of having 2 sizes stiffer front springs (by chance). The car had excellent stability on the straight. I drove on the very edge of the outer white stripe; there was no front end lift or blowovers like before on the big bump.

I still find no faults with the 3-link car although they may show up under very high traction conditions. All of my previous pan cars usually just got faster with more traction; I don't have to change the tire prep or setup at all.

My race may be delayed due to weather.

There may be a production version of this 3-trailing link with Panhard bar rear axle soon. Stay tuned.

John

Last edited by John Stranahan; 01-31-2007 at 03:28 PM. Reason: changed leading to trailing link.
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Old 01-07-2007, 02:11 PM   #800
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sorry, up!!
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Old 01-07-2007, 02:24 PM   #801
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John you should run this car @ the next 24 endurance race. It sounds like it is getting pretty dialed.



Quote:
Originally Posted by John Stranahan
Mathijs-I'll assume then that you did a back to back tests. I'll chop that sucker out at a convenient time during qualifiers. I find that a lot of RC stuff is conjecture. I don't find a lot of full size race cars chopped out like that. I think it probably disturbs the high speed airflow under the car to do so. My other Peugeot body is chopped out. Everything at the back is quite flimsy as a result. Now how do you know you are not letting out the Vacuum (so to speak) rather than damming up the airflow when you chop the rear out like that.


3-link Track Report, vs Wide Pantoura
Track somewhat cleaner than yesterday still a few damp spots. Traction Medium

I ran the two cars back to back again today with the same setups and motors that I used yesterday. There was a bit more traction. Both cars were equally fast on the straight now whereas the 3-link was faster yesterday. The Wide Pantoura has the 3.5 motor the 3-link a 4.5. I think the 3-link car will go faster with the same motor due to better forward traction at speed over the bumps.

I had more cornering traction more forward traction and made fewer mistakes with the 3 link car. I ran it first this time. I ran it second yesterday. The 3 link car has more turn in than the wide car in spite of having 2 sizes stiffer front springs (by chance). The car had excellent stability on the straight. I drove on the very edge of the outer white stripe; there was no front end lift or blowovers like before on the big bump.

I still find no faults with the 3-link car although they may show up under very high traction conditions. All of my previous pan cars usually just got faster with more traction; I don't have to change the tire prep or setup at all.

My race may be delayed due to weather.

There may be a production version of this 3-leading link with Panhard bar rear axle soon. Stay tuned.

John
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Old 01-07-2007, 05:52 PM   #802
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RedlineMO3- The car is dialed now. I have not the funds nor the health for such a project.

Gulf Coast RC Race Track
at Mikes-HobbyShop.com, TrackPhotos
Home of the 2007 Roar Nitro On-Road Nationals




3-Link Car With Panhard Bar
Traction medium Track clean but slightly green, no sugar water treatment Temperatures in the 60-70F range.
Well we had a race. Track was wet in the morning and there was fog. We vacuumed some water and dried the track well. Because of the damp cool conditions which caused sugar crystals to form last time (rock candy), we did not sugar the track this time. This would be the ideal test of the 3-link car. Can it whip some 4 wheel drives with medium traction at hand. Well all I can say is the 3-link car was smoking fast. I qualified second against the 1/10 Nitros and beat or tied 3 of the 4 Spec class 1/8 scales. I won the second qualifier against the race leader. Lin and Binson both qualified consistently better; Lin with a 1/8 scale. I heard lots of complaints of poor traction, but not from me. The car was hooked up very well in the corners as well as on the straight. My fastest lap times were within .3 seconds of my previous best under high traction conditions. Normally they would be about 1-1.5 seconds slower with only medium traction..

Old Troubles resurfaced
As the car gets faster on the straight the strut front end becomes increasingly inadequate. The shock, although it prevented all blowovers previously, does not really have enough travel for the higher speed. I will add some ride height by putting this 3-link rig on the Powell chassis. My Aluminum narrow to wide adaptors kill some ride height on this chassis. I was bottoming out the front again. New scrateches on the Sharpie painted screws.

Layout
Now here are some interesting insights about this new rear suspension. Tony drew us a nice picture of our Layout. I numbered it. You can see there are two hairpins turns 9 and 10 close to the drivers stand. This new suspension has enough turn in that I donít need much brakes here with this car. I still like to use a little. It helps me take a different line than the Nitros and I use the shorter line to make passes.

Wheelies
Just past turn 8 you are going maybe 25 mph and can give it good throttle. I could actually pull the front wheels at this speed from the improved forward traction. I did so twice. No bump assist. It was easy not to do so by using just a hair less throttle. You are getting the most forward traction from a 2 wheel drive when all the weight is on the driving wheels. This did not disrupt the car at all as I am usually going pretty straight before I add huge throttle. You could tune this out if it ever became a problem by adjusting the antisquat to a lower percentage. For me it was a huge thrill. Do that with your other on-road cars. Bring on the L2

LRP Pro Comp
I ran 1 battery for the first two and fastest qualifiers. I used the LRP Pro Comp speed Control with the Novak 3.5 R motor and 48 pitch gears. In the third qualifier, I ran two batteries. The car was quick, at first, in Qualifier 3 but then started to fade some. The last three laps were slow. Just past the finishing loop the car shut off. The top panel had melted off the LRP Competition speed control. It had worked flawlessly for the first two qualifiers. I guess I found its limit (the 3.5R in a 3 link car with two batteries) or it was just well used at this point. Maybe the Tekin will handle this better.

Marty I have some firm orders for a 3-link car from the Hobby Shop Manager, Jeff, at Mikes-HobbyShop.com He said the car was much faster than before. He wants to keep a couple in stock.

Last edited by John Stranahan; 01-08-2007 at 08:51 PM.
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Old 01-07-2007, 06:45 PM   #803
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Note that I have a new race report up above.

Breakage Report
Friday, I hit the boards hard and broke the left side Panhard Bar Mount which was a little on the dainty side. I replaced it with this larger piece. It's probably nice to have a soft part on both ends of the bar here but the frame rail extension appears to be very strong. The frame rail is also supported in a crash by the two lower links and tight clearances in a crash. No other problems to report. I hit the boards twice today on both sides. No damage. I got nailed in the ass hard by a Nitro car while I was parked against the side of the pit lane. He did not see me at all and took off from 15 ft back. It spun me 180 degrees. No Damage. No ruined spur. The photo shows the improved bar mount and the melted off heat sink. That's mighty good heat control adhesive tape that heatsink is mounted with. You just stick the heatsink on when you mount it.
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Attached Thumbnails
Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-three-link-left-panhard-mount-resized.jpg  
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Old 01-07-2007, 08:20 PM   #804
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Where can i source CF of that quality/thickness? Do you have a link to a website i can purchase from?
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Old 01-07-2007, 09:43 PM   #805
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Dave-I used Cobra (the lathe guys) brand of .084 graphite sheet. I got it at my local hobby shop.
PenguinRC.com also sells this stuff as well as G10. I think their good grade of graphite sheet is called quasi grade. I am not sure. The G10 is flat black or in colors at a knife shop. My 1/4 inch thick G10 I got at a knife shop. G10 is a fiberglass with epoxy product. The graphite sheet is a graphite fiber with epoxy product.

http://www.texasknife.com/store/s-pages/TKS_MainframeStore.htm

I found this stuff fairly easy to work with by hand with a Dremel. I used a scroll saw on some of it just because I had one. The Dremel with quite a few of those thin blades would have done the job. Wear a Respirator cutting or sanding. Hope some of you guys get enthused about making something interesting for your car.
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Old 01-08-2007, 05:43 AM   #806
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Thanks so much for the information John.

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Old 01-08-2007, 02:29 PM   #807
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john, i'm a little confused by a previous post where you refer to your antisquat in percentages as i'm a touring car guy primarily, or at least that is what i know better.. are you running antisquat or prosquat? perhaps they act differently on touring cars, than pans, but prosquat adds rear traction and antisquat reduces it on acceleration... right?
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Old 01-08-2007, 03:31 PM   #808
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Dave-you are welcome. If you end up drilling holes in this stuff it's best to have a small drill press or maybe use the Dremel at very high speed. A portable power drill tends to walk all over the place as it hits angled layers of the fiber. You end up with a crooked hole.



TallyRC-I posted a figure that may help you understand antisquat percentage up above and also a long post on the differences between independent and solid axle antisquat. You are incorrect or not specific as to what traction is improved, I believe. I'll try to summarize.

On a four wheel drive independent rear suspension RC car this is the observed effect. If I raise the front of the rear lower A-arm up a degree or two, this makes the rear suspension stiffer on power. The rear end looses cornering grip as a result; the car gets loose.
Weight is transfered to the rear quicker. There may be more forward traction under some conditions like an off-road 2 wheel drive buggy launching off a jump. Four wheel drive cars are different and do not get better forward traction when you transfer weight to the back. The front wheels pull as well and need the weight. You actually loose efficiency at the rear and it may not pull as hard. The effect on forward traction on touring cars is small enough to neglect. Antisquat has a large effect on cornering and makes the car go poorly through bumps.

I postulated way back about 4 years ago on an antisquat thread that I started in preparation for writing RC Electric Car Reference that a solid axle rear car may behave differently and that we should build one. Well now I have. The books (full size car race books) say that for a 2 wheel drive, antisquat will cause the chassis to raise up increasing the load on the rear tires and give you more forward traction on power out of a corner. I think the books are dead on here and my new 3 link car proves it. This applies best to to two wheel drive cars with a solid rear axle. The effect is very significant.

So here is the thing. If the force line the red line in the figure is below the center of gravity or at the center of gravity you will get some chassis lift. The lower this red line is the more the force will just propel the car forward and not lift the chassis. So higher is more antisquat. At the center of gravity is 100%. The percentage is an arbitrary construction of one author Carol Smith in Tune to Win. We could talk about the angle of the red line as well, but it would not show the upper limit of usefulness to antisquat which would be at the center of gravity. If the red line goes below the ground we have prosquat.

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If you would like to see excerpts of the all new 3rd edition of RC Electric Car Reference in "Radio Control Car Action Magazine" send them an e-mail to this published address [email protected]. They have promised me a column with excerpts after requesting this new version of the book. I no longer sell copies.

Quote from our local track thread in Texas racing.
"nice day of club racing okay turn out about 9 touring and four 1/8 scale but lots of fun. Med. traction but still very fast lap times oh and one very fast electric pan car that was in the front for the first two qulifiers . wow that was nice to watch . cool and i will see you guys agian on the 21st ..."

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Old 01-09-2007, 02:21 PM   #809
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Quote:
Originally Posted by John Stranahan
Dave-you are welcome. If you end up drilling holes in this stuff it's best to have a small drill press or maybe use the Dremel at very high speed. A portable power drill tends to walk all over the place as it hits angled layers of the fiber. You end up with a crooked hole.
Yes, thanks for the reminder... its been a while since i have done anything major with CF, sharp bits/blades/proper tools and patience is the best way to ensure a fine finished product. After a long break from R/C i am finally getting off my tail to finish a project i have worked on for quite some time. Reading through your thread here has reminded me of how much fun R/C used to be to me.

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Old 01-09-2007, 02:34 PM   #810
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Dave-Good luck. I never know when I am dealing with an experienced hand.


3 leading Link Rear Axle with Panhard Bar
on Powell Wide Pantoura chassis
Here is the three leading link Rear Axle on the Powel Wide Pantoura Chassis. It was a nice fit. I did have to drill two additional holes to secure the front of my frame rails/battery supports. I'll need to make some kind of light spacer to run a single LiPo pack. 39.7 ounces ready to race with transponder. Gear 7.50. Novak 3.5 R motor. Novak GTB controller.
John
Attached Thumbnails
Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-three-link-panhard-bar-powell-chassis-resized.jpg  

Last edited by John Stranahan; 01-09-2007 at 02:44 PM.
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