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Old 02-27-2008, 11:00 AM   #1921
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that looks really nice and neat, John.

How close is it to the third link? Looks really close - does it interfere at all?
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Old 02-27-2008, 11:57 AM   #1922
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Boomer-Thanks. The speed control does not interfere at all with the links. the pod is very free in roll and bump. The aluminum angle is a very rigid little piece so it should not flex into inteference.
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Old 02-29-2008, 12:09 PM   #1923
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BMI DB10R
BMI has realeased a series of pictures of the new BM1 DB10R pan Car. This is a 200 mm wide 4 cell or saddle Pack LiPo car. Here is one of pictures lightened a bit to look at the fiberglass side links. It is a center pivot link car but the fiberglass side plates have an additional function to control pod roll much like a U plate car would have. It would be nice to have a clear picture of the rear of the car from the top without electronics showing the novel feature.

This would be the perfect car to try twin center shocks. The shocks would extend from the forward tips of the forward nerf triangles straight back to the top pod plate corners. My guess is that rear wheel return to ground would be much improved.

my picture upload failed. I will add it later.
John
Attached Thumbnails
Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-bmi-db10r.jpg  

Last edited by John Stranahan; 02-29-2008 at 08:13 PM.
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Old 02-29-2008, 01:06 PM   #1924
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Quote:
Originally Posted by John Stranahan View Post
BMI DB10R
BMI has realeased a series of pictures of the new BM1 DB10R pan Car. This is a 200 mm wide 4 cell or saddle Pack LiPo car. Here is one of pictures lightened a bit to look at the fiberglass side links. It is a center pivot link car but the fiberglass side plates have an additional function to control pod roll much like a U plate car would have. It would be nice to have a clear picture of the rear of the car from the top without electronics showing the novel feature.

This would be the perfect car to try twin center shocks. The shocks would extend from the forward tips of the forward nerf triangles straight back to the top pod plate corners. My guess is that rear wheel return to ground would be much improved.

my picture upload failed. I will add it later.
John
I dont think the DB10R needs any improvements
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Old 02-29-2008, 03:59 PM   #1925
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Quote:
Originally Posted by John Stranahan View Post
BMI DB10R
BMI has realeased a series of pictures of the new BM1 DB10R pan Car. This is a 200 mm wide 4 cell or saddle Pack LiPo car. Here is one of pictures lightened a bit to look at the fiberglass side links. It is a center pivot link car but the fiberglass side plates have an additional function to control pod roll much like a U plate car would have. It would be nice to have a clear picture of the rear of the car from the top without electronics showing the novel feature.

This would be the perfect car to try twin center shocks. The shocks would extend from the forward tips of the forward nerf triangles straight back to the top pod plate corners. My guess is that rear wheel return to ground would be much improved.

my picture upload failed. I will add it later.
John

You can see the suspension pretty clear in this pic of my prototype DB12R. It shares the same suspension with its big brother.

If you would like a closer pic let me know.
Attached Thumbnails
Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-db12r-1.jpg  
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Old 02-29-2008, 08:34 PM   #1926
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Jason-Thanks for the pic. Yes I would not mind a close up pic. I would like to see a side view of the side plates. I can see now that there is a small T-bar in the center. I assume those fiberglass side plates add to the roll stiffness of the pod. I can't quite see how they work from pics that are available. Looks like you have a good customer there in MarcosJ.

Marcos-Some things are done just because they have always been done that way. On closer scrutiny one might find a better way. There is not a car in existance that cannot be improved. Marketing the improved car is another story. This thread is more or less an experimental pan car thread now, so that's what I talk about. Experiments.
John

200mm 3-link Oval Car Practice Session
Our short oval is finalized for now. The run line is about 175 feet. I cut some "snowbird like", ice, ends from fiberglass shower board. It worked well. They lube it up with pledge or something similar to create a penalty spin for driving on it. I have some more experience with the 13.5 motor now. It likes a gear of 84/22 on short rear tires. It likes the short wiring. I am using about 90-95% throttle on the corners so the car is steering really well.


Rear Steer
I did an experiment with rear steer today. Some oval chassis and my 3 link allow this. A common problem with pan cars is they hook or oversteer on corner exit if you apply throttle too early before they get straight. On the road course I just wait a few more milliseconds and then start my throttle roll on. On the oval I am at 90% throttle on exit with this motor and want to go full throttle immediately. I fixed part of this problem by reducing caster on the right front to 2 degree. I tried rear steer today to accomplish the rest of this. I made the rear end steer to the left. When you apply throttle now right on corner exit the car will accelerate straight and will allow me to steer with the radio wheel right to the outside board without a tendency to hook in and waste precious inches and momentum with a zig zag. I don't know if this is the accepted way to rear steer an oval car, but it worked well for me on this short oval with good traction. I exxagerated the angle to about 5 degrees left steer (the pod is rotated counterclockwise with respect to the car on the vertical axis). Now this is going to cause the car to crab a little sideways when driving straight, left side leading. This did not seem to be noticable or a problem in any way. It will increase the air resistance. I might reduce it some and try it again this way. Today I wanted a noticable effect.

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Old 03-01-2008, 04:17 AM   #1927
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Hey john,

I will take some pics today for you. There is no center t bar. That is a battery locator.The way it works is this:

There are 3 pivots,1 center and 1 on each flex plate. The ones on the flex plate are on the underside. There is a set screw on top that pushes on a balled washer that sits on top of the pivot balls in the flex plate that allows you to remove the verticle play in the rear pivots. With that being said, you now have a fully isolated suspension system. The side plates give you the progressive spring tension of a T bar and the center shock gives you your for and aft spring tension. We are also using linear front springs now that make the car roll more evenly for better rotation. I will post some pics for you later today. My new rear suspension has been working extremely well and has been proven to be extremely durable.
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Old 03-01-2008, 08:39 AM   #1928
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John
just go to the BMI website and download the instructions from the DB12R. There you could see very good how the rear suspension is made. I also didnīt see very much from the pictures and downloaded the instructions now. I think the BMI rear suspension is really interesting and different from other cars.
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Old 03-01-2008, 10:25 AM   #1929
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Jason- thanks for the detail.

The instructions on the DB12R were very helpful in describing the rear suspension. Nice. Thanks. Here is a link. I swore that you had a bottom view up on the other thread that clearly showed the center football and pivot ball arrangement, but then I could not find that photo later. What I did not know was if the front of the side plates were firmly clamped or in some kind of flexible spring loaded holders. I see now they are firmly clamped up front.
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Old 03-03-2008, 11:51 AM   #1930
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CRC Battle Axe
CRC has just realeased an oval version of their new 200 mm pan car called the Battle Axe. The links are angled in on this car to make room for the rear cell on the left mounted battery tray. There is room for a large speed control on the left rear. Gone are the damper tubes that gave me trouble. They are replaced with side shocks. A fifth body post supports the hood; I like this. That is some really nice metal and graphite work on the rear pod; everything is kept very low while still being structurally sound. That looks like a PRS spur; very nice and light. The front end is a custom CRC produced second generation unit that is also used on the 1/12 scale car. It has height adjustable inner upper A-arm supports and a large pivot ball outboard.

(Send me one of those puppies to test and I will start a new thread on it.)
John
Attached Thumbnails
Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-crc-battle-axe.jpg  

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Old 03-03-2008, 02:15 PM   #1931
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Rollout
Here is a discussion of rollout that I have moved from another thread. I understand that the key to rollout is what produces the lowest lap time.

bigloves question-
"3.00 rollout equals what to a 2.60 rollout"

Rollout is how many inches per motor revolution the rear tire travels. The more inches it travels per motor revolution the taller the gear. The 3.00 rollout is taller than the 2.6 rollout. There are more teeth on the pinion on the 3.0 rollout.

If you want to duplicate a rollout first measure your tire. Mine is 2.1 inches. multiply by pi, 3.14, to get the tire diameter. Mine is 6.59 inch. Divide this by the rollout and you get your pinion spur ratio. If I divide by 3, I get a 2.19 ratio.

If I am using a 100 tooth 64 pitch spur then divide 100 by 2.19 to get your pinion. You get a huge 45 tooth pinion. The 2.6 rollout gives you a 39 pinion.

To calculate your rollout (Tire Diameter x 3.14)/(Spur/pinion ratio) You can use inches or millimeters.

That RC10L4 has holes to adjust the battery tray fore an aft. A slider has slots. Not much difference there as long as the holes are close enough to gether.

Here are some more thoughts on rollout. If I were on a hard banked velodrome where lap two could be significantly faster than lap one due to a slow build up of speed then I could use a huge rollout. This would probably be the highest of the rollouts for a given motor. ( I have seen an adaptor to put spur gears on the motor.) If the track is flat asphalt and the car slows down significantly in the corners where lap 1 speeds equal lap 2 speeds then you would not need as much rollout. You need to accelerate better on the straights; there is not such a speed buildup from lap one to lap two. Now where our track sits between these two cases is a matter of debate. I suspect it is more like the second case where you don't need as much rollout.

From a motors view if you could have the motor at maximum power for most of the lap then you should get the most out of it. So where is that. I did some calculations and peak amperage on four cell should be about 45 amps or so. This means peak power is at about 22 amps or so. If we could get the motor to pull 22 amps for the average our performance will probably be better. I am going to test my ampdraw maybe wednesday.
When I see these huge rollouts and pinions all I think from my testing is horribly overgeared. I put two more pinion teeth on my rollout and the car got sluggish. These rollouts are adding 18 more teeth. When I get lapped 5 times then I will increase the rollout for the second heat. Heck I don't own a 38 tooth 48 pitch pinion.

Another factor I don't consider is that a higher rollout has the effect of numbing the motor. This lets you corner at the limit without possible disruptions from too much motor torque. I'll have to see.
john

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Old 03-05-2008, 08:27 PM   #1932
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200 mm Oval 3-link Pan car

I did some more testing on the pan car today. Our run line is now 180 feet. First I wanted to make sure rear steering was helping me, so I took it all out. My oversteer problem on corner exit returned. The rear steer definitely helped this problem and made the car much more drivable on corner exit. I use quite a bit of rear steer about 5 degrees.
I had used some wheel offset to address the same problem This remained on the car left rear out, right front in. Both of these should make the car steer right on corner exit. The effect is mild, though, and this adjustment is completely masked by the tendency of a pan car to hook on corner exit. Use it for fine tuning.
I reduced caster to 0 on both sides. Now what this is supposed to do is increase steering early in the corner and relax it late in the corner. I now had huge corner entry steering, huge on throttle steering, but it was way too much. I had made the adjustment to reduce scrub as I had read that less caster reduces scrub. I plan to put my 2 degreees back on.
I had gone to a smaller wing to reduce air drag. I had some corner exit spins. I will need to try this smaller wing again when I get my alignment for the front end in better order. It looks like on our flat asphalt oval 2 degree caster on both sides is good. The car handles much easier.

My runtime would have been 26 minutes. I quit at 19.5 minutes and discharged the rest on the Turbo thirty. It was dusty from tree pollen today. They tell me I should gear up 10 teeth (48 pitch) on the pinion!

The Trinity EP battery tested well today. 3783 mA-h and 1.247 volts/cell at a 20 A discharge. These numbers are both higher than on the first test I made which were 3661 mA-h capacity with 1.21 volt/cell on the first cycle. I have maybe 7 cycles on the pack now. Note that these best numbers are matched by my FMA direct LiPo's for 6 cell use. At higher amperage the Lipos would test better than the NiMH.

OK, I put on the tiny 100 tooth 64 pitch spur and am ready to gear to the moon tomorrow.
john
Attached Thumbnails
Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-oval-track-layout-002.jpg   Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-oval-track-layout-004.jpg   Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-oval-track-layout-007.jpg  

Last edited by John Stranahan; 03-13-2008 at 01:24 PM.
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Old 03-06-2008, 04:28 PM   #1933
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Gearing
Novak 13.5, short oval
I tried two gears on the short oval. 100/30, which was inline with what I had been using, and 100/37 (2.7 ratio,2.4 in/rev rollout) which was the largest 64 pitch pinion I had. There was an improvement much to my surprise. I found a huge 34 tooth 48 pitch pinion in stock in town. I will try 72/34 next( 2.11, 3.05 in/rev). This is in line with what the oval guys are using. Gearing with fairly pathetic 4 cell is new to me.

These taller gears should move me toward a higher average amp draw and closer to the motors peak power.

Caster
I settled on 2 degrees caster on the right side and 0 degrees left. I had no complaints like this.

Wing
the small wing worked fine with the 2 degrees caster.

Rear steer
The car was perfect with about 5 degrees of rear steer and the low gear. I actually got more punch out of the corner with the higher gear. This caused a small tendency to oversteer. I used countersteer to keep it straight. I may add a little more rear steer to compensate for the increased punch.



Oval race on Sunday.

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Old 03-09-2008, 05:15 PM   #1934
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Race Report Oval 200 mm 3-link pan car
traction medium, Geared 37/100 2.2 inch tire, 2.55 inch/revolution.
Novak 13.5
Well the 3 link car proved quite adequate on the flat asphalt oval. There were a variety of chassis including two new custom works cars and several RC10L4s.
My car qualified first in all three heats and won the main. My fastest lap was 1 hundredth slower than Mike. D's fastest as he was chasing me in the main. I do admit I punted him hard into the weeds in lap two as he slowed for the corner. My apologies. Exciting racing all the way to the end. Three cars finished on the same winning lap of 62 laps for 5 minutes. One car only 1/3 lap behind and charging hard. Lapped traffic was the great equilizer for all of us on the lead lap.

Here are some numbers from the race.
I only own 1, 4 cell pack which I used for all races and practice. It seemed to be enough.
There was plenty of battery trouble from those that used Novak solder to join their four cell packs. You need some flux with this solder.
It took 20 minutes at 5 amps to recharge. Only used about 2000 mA-h in each race.
My gear choice was limited as 4 guys were using my pinions. I would have gone up and down a tooth had I the pinions in hand. The road race guys finished one and two most of the heats because of favorable ratios, the oval guys caught up later in the main. I think they reduce their rollout a bit for this short track. I'lll find out later.
My McAllister COT body worked well with a bigger than stock wing, but may be a tad slower than the protoform bodies which are well developed for the oval. If COT is required, my body will be well setup.

Does the 3-link have an advantage on detuned 4 cell 13.5. Probably only a little. It certainly makes the car easy to drive. I had no harsh mistakes in 3 heats of qualifying while the other cars were spinning out regularly. Some in equally experienced hands. We had some pollen on the track. With a 6.5 and 6 cell the advantage of the 3-link would be large. Making the pan car easy to drive would be a great thing. We may have a bigger(open mod) outdoor oval eventually as well as an indoor oval.

Black Hardcoated 64 pitch pinions did not last two days on some cars. The coating was completely gone on one. I will probably look for steel pinions.

John

Last edited by John Stranahan; 03-11-2008 at 09:51 AM.
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Old 03-10-2008, 03:24 AM   #1935
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Congratulations John, sounds like you adapted very quickly.

Have you ever tried RW Pinions? I've used them for years and they last for years too http://www.rwracing.co.uk/home/main.html
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