8LikesCRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks
10-26-2008, 03:14 PM
#331
Custom Works Aggressor Slider
Jimmy brings a different chassis every week lately, it seems, and we tune it up. This one was a Custom Works Agressor Slider. Some of the adjustments available are T-plate offset, pod offset, right rear steer and sliding body posts which allow you to center the body over the tires once you have the car dialed in.
Also the battery tray slides forward and back hence the name Slider.
Here were the problems
Oversteer on Corner Entry
Oversteer Mid Corner
horrible corner exit hooking
The car was basically undriveable. Most cars exhibit the last problem but not the first two. The car was running 3 pinks and a purple right front so the problem was not tires. Increasing left downtweak by tightening the right rear shock collar untill the collar would no longer adjust did not help.
So here is what we noticed at the bench. There was right rear steer dialed in. Let me discuss this just a bit. When a car reaches a steady state in a corner and is drifting there is a certain slip angle that is developed by the right rear tire. The tire aims slightly inward of the actual path. Increasing this slip angle with rear toe in (like almost every other race car in the universe) or left rear steer (like my oval car) increases rear grip and does wonders to correct corner exit ovesteer. Most of the cornering effort is at the right rear since it is loaded up. The reason for corner exit improvement with left rear steer is as the rear steers left the car goes right on corner exit. Just where you want it to go toward the outside board.
Adding right rear steer does just the opposite, it decreases the slip angle, the rear is loser; in addition, though, on corner exit, the rear steers right the car goes left right into the center board with a big hook. A couple of our guys went to the carpet nats. They could not find a soul using right rear steer. So maybe it's just a phase oval went through. We took out the right rear steer.
The car was improved early and mid corner. It still had too much corner exit hooking with a good ammount of left down tweak. This called for more serious investigation. We got out the setup board. I aligned the center of the front of the chassis, the center of the rear of the chassis (not the pod) and looked at where the rear tires ended up. If you were road racing you would want the outside edges of both rears to be 100mm from the center giving you your 200 mm rear width.
Our right tire was at 110 mm the left was at 90. This means the offset pod was to the right 10 mm more than it should have been. This gives you a torque steer that is greater on the right rear. It has a longer lever. This is exactly what you don't want on corner exit. We moved the pod over to the correct position to make the car even. Now on the oval one powerful tuning aid to correct corner exit hooking is left rear wheel offset. We added a 10 mm spacer inside of the left wheel. This increased our width to 210. We moved one body post over to center the body on the new setup. We did have to redrill the hole for the right body post as it was positioned at its limit already. The car looked good. We put it on the track and it was very drivable now. All it needs is maybe another ounce of left downtweak. This is going to take a slightly different shock setup as the adjustment collar on the right rear is all the way in.
A very successful test and tune. I could tell by the sound of the motor that he was applying maybe 50% more throttle on corner exit instead of just babying the car around now.
John
Jimmy brings a different chassis every week lately, it seems, and we tune it up. This one was a Custom Works Agressor Slider. Some of the adjustments available are T-plate offset, pod offset, right rear steer and sliding body posts which allow you to center the body over the tires once you have the car dialed in.
Also the battery tray slides forward and back hence the name Slider.
Here were the problems
Oversteer on Corner Entry
Oversteer Mid Corner
horrible corner exit hooking
The car was basically undriveable. Most cars exhibit the last problem but not the first two. The car was running 3 pinks and a purple right front so the problem was not tires. Increasing left downtweak by tightening the right rear shock collar untill the collar would no longer adjust did not help.
So here is what we noticed at the bench. There was right rear steer dialed in. Let me discuss this just a bit. When a car reaches a steady state in a corner and is drifting there is a certain slip angle that is developed by the right rear tire. The tire aims slightly inward of the actual path. Increasing this slip angle with rear toe in (like almost every other race car in the universe) or left rear steer (like my oval car) increases rear grip and does wonders to correct corner exit ovesteer. Most of the cornering effort is at the right rear since it is loaded up. The reason for corner exit improvement with left rear steer is as the rear steers left the car goes right on corner exit. Just where you want it to go toward the outside board.
Adding right rear steer does just the opposite, it decreases the slip angle, the rear is loser; in addition, though, on corner exit, the rear steers right the car goes left right into the center board with a big hook. A couple of our guys went to the carpet nats. They could not find a soul using right rear steer. So maybe it's just a phase oval went through. We took out the right rear steer.
The car was improved early and mid corner. It still had too much corner exit hooking with a good ammount of left down tweak. This called for more serious investigation. We got out the setup board. I aligned the center of the front of the chassis, the center of the rear of the chassis (not the pod) and looked at where the rear tires ended up. If you were road racing you would want the outside edges of both rears to be 100mm from the center giving you your 200 mm rear width.
Our right tire was at 110 mm the left was at 90. This means the offset pod was to the right 10 mm more than it should have been. This gives you a torque steer that is greater on the right rear. It has a longer lever. This is exactly what you don't want on corner exit. We moved the pod over to the correct position to make the car even. Now on the oval one powerful tuning aid to correct corner exit hooking is left rear wheel offset. We added a 10 mm spacer inside of the left wheel. This increased our width to 210. We moved one body post over to center the body on the new setup. We did have to redrill the hole for the right body post as it was positioned at its limit already. The car looked good. We put it on the track and it was very drivable now. All it needs is maybe another ounce of left downtweak. This is going to take a slightly different shock setup as the adjustment collar on the right rear is all the way in.
A very successful test and tune. I could tell by the sound of the motor that he was applying maybe 50% more throttle on corner exit instead of just babying the car around now.
John
Last edited by John Stranahan; 10-30-2008 at 04:42 AM.
10-26-2008, 04:00 PM
#332
Tech Apprentice
Hi John,
Regarding the front end mods you listed above, it appears to be a hybrid between the associated dynamic strut and the crc pro strut (pivot ball and multi piece knuckle replaced with full kingpin and one piece knuckle). Is there any performance gains with running this over the associated dynamic?
thanks
scott
Regarding the front end mods you listed above, it appears to be a hybrid between the associated dynamic strut and the crc pro strut (pivot ball and multi piece knuckle replaced with full kingpin and one piece knuckle). Is there any performance gains with running this over the associated dynamic?
thanks
scott
10-26-2008, 06:02 PM
#333
scott- no performance gain over a similar Associated setup that has long kingpins and the longer wolfe springs. Note that you have had to invest some money and time on the associated front end before it performs the same as the CRC pro strut front end. Mine is going to be very nice looking with the red reactive caster blocks that are coming. It will have adjustable tension on the lower pivot ball to keep it from binding up. There is also no performance gain over the stock pro strut front end. The only gain will be in ruggedness compared to the stock pro strut front end, mainly from having that trailing axle that is 1/8 steel (better bearings) and not directly surounding the kingpin like an inline axle. There is some flex available.
john
john
10-28-2008, 05:18 PM
#334
Front Diffuser
This is the third in a series of front diffusers. The first was a LEXAN model for a high speed car. It improved the "takeoff" speed in the bumps by 10 mph. That means the car was going 10 mph faster before a bump would send it flying at over 60 mph. The second was a foam model carved into a large foam bumper. Both of these only had diffuser action near the wheels. The theory is that the wheels are always pulling a large amount of air under the front bumper lip. If you separate or Diffused this air upward you create a vacuum which holds the front end down. Each prototype had its problems; the LEXAN model worked well but on the road track a bump witht the boards would permanently deform it and make the car undriveable. The foam model was better with impacts but it could not be made particularly smooth or even half way nice looking. This third attempt uses an inverted HPI wing from their molded wing set. This is the bi-wing shown lowest in the link. I have sealed the gap with red tape. Because the wing goes full width it might be more effective. There is plenty of air that comes in under the middle of the car. Usually this air just exits low in the rear of the car (as determined by wind tunnel testing). Now it will be diffused up and maybe concentrate some downforce on the leading edge of the body. I should be able to tell its effectiveness by any change in turn in, or oversteer/understeer balance on the road track. Test tomorrow. The flexible wing has the right material for this position.
Inerter prototype
I received the new case, new gears, and servo mounts to mount my inerter into a suitable center pivot link car as soon as one becomes available. I need the traditional style of pan car where the roll and bump action are divorced from each other. This creates problems through the bumps that the inerter might cure. Test in a month or two. I have adjustable leverage to change the inertance but may also need to remove a set of gears after preliminary testing. I have an idea on that.
This is the third in a series of front diffusers. The first was a LEXAN model for a high speed car. It improved the "takeoff" speed in the bumps by 10 mph. That means the car was going 10 mph faster before a bump would send it flying at over 60 mph. The second was a foam model carved into a large foam bumper. Both of these only had diffuser action near the wheels. The theory is that the wheels are always pulling a large amount of air under the front bumper lip. If you separate or Diffused this air upward you create a vacuum which holds the front end down. Each prototype had its problems; the LEXAN model worked well but on the road track a bump witht the boards would permanently deform it and make the car undriveable. The foam model was better with impacts but it could not be made particularly smooth or even half way nice looking. This third attempt uses an inverted HPI wing from their molded wing set. This is the bi-wing shown lowest in the link. I have sealed the gap with red tape. Because the wing goes full width it might be more effective. There is plenty of air that comes in under the middle of the car. Usually this air just exits low in the rear of the car (as determined by wind tunnel testing). Now it will be diffused up and maybe concentrate some downforce on the leading edge of the body. I should be able to tell its effectiveness by any change in turn in, or oversteer/understeer balance on the road track. Test tomorrow. The flexible wing has the right material for this position.
Inerter prototype
I received the new case, new gears, and servo mounts to mount my inerter into a suitable center pivot link car as soon as one becomes available. I need the traditional style of pan car where the roll and bump action are divorced from each other. This creates problems through the bumps that the inerter might cure. Test in a month or two. I have adjustable leverage to change the inertance but may also need to remove a set of gears after preliminary testing. I have an idea on that.
Last edited by John Stranahan; 10-28-2008 at 05:28 PM.
10-29-2008, 06:13 AM
#335
Left Rear Steer
I mentioned previously that one of our drivers is converting an RC10L2 wide pan into an oval car. He has succesfully used an L2O bottom plate and created an offset pod and 200 mm rear width. The front was a little too wide still for the bodies. He decided to redrill the #8 screw holes on the left side of the chassis farther inward. This by coincidence is going to create some rear steer. A 1/4 inch movement of one wheel moves the center 1/8 inch and you get about .7 degrees of rear steer (ARCTan(1/8/10). I am running about 1.7 degrees.
I have not seen an oval chassis that allows a left rear steer adjustment, but I have seen plenty where the front wheels can move in or out on the chassis. Try moving the right side out left side in to experiment with some left rear steer. The body will have to be reset eventually. Give us a report. Use this to cure some residual corner exit hooking you may have. The less of this problem you have the more throttle you can use on corner exit.
John
I mentioned previously that one of our drivers is converting an RC10L2 wide pan into an oval car. He has succesfully used an L2O bottom plate and created an offset pod and 200 mm rear width. The front was a little too wide still for the bodies. He decided to redrill the #8 screw holes on the left side of the chassis farther inward. This by coincidence is going to create some rear steer. A 1/4 inch movement of one wheel moves the center 1/8 inch and you get about .7 degrees of rear steer (ARCTan(1/8/10). I am running about 1.7 degrees.
I have not seen an oval chassis that allows a left rear steer adjustment, but I have seen plenty where the front wheels can move in or out on the chassis. Try moving the right side out left side in to experiment with some left rear steer. The body will have to be reset eventually. Give us a report. Use this to cure some residual corner exit hooking you may have. The less of this problem you have the more throttle you can use on corner exit.
John
Last edited by John Stranahan; 11-02-2008 at 04:01 PM.
10-29-2008, 05:13 PM
#336
Modified CRC Front End
All the parts were in to build my front end so I assembled it. I came upon some problems. Firstly the kingpin need not be so long as I normally use on Associated suspensions. A 1.1875 (1-3/16 inch) pin was sufficient. I used Titanium Hinge pins From a Lunsford Punisher set for the Losi XXT part number 3066. I could not find the titanium pins separately. These pins are sized .124 or slightly less than 1/8. Thus they were a very good fit to Teflon coated Aluminum pivot balls from RC4less.com. The set also has a pair of long 1.142 inch pins and also two of the 1.1875 pins that I needed. I polished the pins. I hand drilled the steering uprights with a .124 drill for a nice low drag fit to the pins.
Secondly and probably a show stopper for most people is the CRC lower arm is slightly shorter than the typical Associated style arm. This means the upper arm when assembled Associated style ends up too long. I nipped 1/8 inch off the arm, drilled the hole in the arm deeper, nipped 1/8 inch off the ball cup and Dremmeled 1/8 inch off the tie rod shaft only on the outboard end. I am satisfyid with the strength and can do this very quickly in the field. Most people don't like to cut parts so there you have it.
Anyway. Here are a couple of pics. What a beautiful set of parts. Here are some features saved from the Prostrut front end.
It uses the inexpensive molded ride height spacers and lower Arm. The 5 mm spacer is attached in the pic.
It has a tension screw on the lower pivot ball. Thus the mold can be a tad loose on the pivot ball and then you tighten it up just so there is no play.
There is a really nice set of CNC'd aluminum Reactive Caster blocks. The 0 degree block is shown installed. I have a 5 degree block to try on the left. On road I use two 5 degree blocks.
I have also used one spacer from the roll center kit to space the inner upper A-arm pivot up to a more parallel position with respect to the lower arm.
The upper A-arm hinge pin cap makes adjusting caster a snap instead of a dreaded operation likely to deform the caster shims.
Some strong additional parts.
The CRC, CNC machined Delrin steering block.
Lunsford Punisher 1-3/8 inch steering tie rods and rod ends.
These are CRC Titanium Axles.
Note that the CRC prostrut front end should perform the same as this one. I have reviewed it and have pictures earlier in the thread as well as building tips for a smooth front end. This one may be more rugged.
Pic #3. This is the left side suspension. Front of car would be to the left. Note the top of the kingpin tilted back. This is the caster setting. Note also the axle trails the kingpin slightly (by 1/8 inch center to center) This adds to the caster and may reduce turn in. Reduce your caster to get it back. The fact that the axle trails means that it is ineffective in bending your kingpin any more. Instead the steering block just flexes.
There is an extended upper arm part that will allow the use of this front suspension without cutting the A-arm. The part is CRC 33277. It is made of graphite and moves the reactive caster blocks inward a bit. I have one on the way for a look.
John
All the parts were in to build my front end so I assembled it. I came upon some problems. Firstly the kingpin need not be so long as I normally use on Associated suspensions. A 1.1875 (1-3/16 inch) pin was sufficient. I used Titanium Hinge pins From a Lunsford Punisher set for the Losi XXT part number 3066. I could not find the titanium pins separately. These pins are sized .124 or slightly less than 1/8. Thus they were a very good fit to Teflon coated Aluminum pivot balls from RC4less.com. The set also has a pair of long 1.142 inch pins and also two of the 1.1875 pins that I needed. I polished the pins. I hand drilled the steering uprights with a .124 drill for a nice low drag fit to the pins.
Secondly and probably a show stopper for most people is the CRC lower arm is slightly shorter than the typical Associated style arm. This means the upper arm when assembled Associated style ends up too long. I nipped 1/8 inch off the arm, drilled the hole in the arm deeper, nipped 1/8 inch off the ball cup and Dremmeled 1/8 inch off the tie rod shaft only on the outboard end. I am satisfyid with the strength and can do this very quickly in the field. Most people don't like to cut parts so there you have it.
Anyway. Here are a couple of pics. What a beautiful set of parts. Here are some features saved from the Prostrut front end.
It uses the inexpensive molded ride height spacers and lower Arm. The 5 mm spacer is attached in the pic. It has a tension screw on the lower pivot ball. Thus the mold can be a tad loose on the pivot ball and then you tighten it up just so there is no play. There is a really nice set of CNC'd aluminum Reactive Caster blocks. The 0 degree block is shown installed. I have a 5 degree block to try on the left. On road I use two 5 degree blocks. I have also used one spacer from the roll center kit to space the inner upper A-arm pivot up to a more parallel position with respect to the lower arm. The upper A-arm hinge pin cap makes adjusting caster a snap instead of a dreaded operation likely to deform the caster shims.Some strong additional parts.
The CRC, CNC machined Delrin steering block. Lunsford Punisher 1-3/8 inch steering tie rods and rod ends. These are CRC Titanium Axles.Note that the CRC prostrut front end should perform the same as this one. I have reviewed it and have pictures earlier in the thread as well as building tips for a smooth front end. This one may be more rugged.
Pic #3. This is the left side suspension. Front of car would be to the left. Note the top of the kingpin tilted back. This is the caster setting. Note also the axle trails the kingpin slightly (by 1/8 inch center to center) This adds to the caster and may reduce turn in. Reduce your caster to get it back. The fact that the axle trails means that it is ineffective in bending your kingpin any more. Instead the steering block just flexes.
There is an extended upper arm part that will allow the use of this front suspension without cutting the A-arm. The part is CRC 33277. It is made of graphite and moves the reactive caster blocks inward a bit. I have one on the way for a look.
John
Last edited by John Stranahan; 11-05-2008 at 07:02 AM.
10-30-2008, 11:01 AM
#337
Front Diffusers on the wide pan or velodrome Oval
Most late build GTP cars and our current crop of LMP Lemans cars have a front diffuser built in. This was added or improved after a disasterous series of full size cars taking flight. I recall my wide pan car doing the same in its early days. I would be in a race, In the middle of a swarm of nitro 1/10 scale, ready to make a pass early in the sweeper and the car would go airborne at about 53 mph. A lot of times it would do one backflip land on the tires and I could continue. At this point the car was stable in practice, no blowovers, but had trouble in traffic. A bump was always involved.
I constructed a series of front diffusers of varying utility. At first I did this for some high speed runs with B4maz. There is a photo series below. The first on the left was made of .030 Lexan. It increased the blowover speed by 10 mph to 63 mph. Thus it was effective, but on the track it was easily damaged and dragged the ground. I made the second from foam. It seemed to work as well as the first but was butt ugly. The third works better than either. I tested yesterday. This last model goes the full width of the front end. On a bump that launched the car with the foam model into an even glide back to the ground catching about 3/4 inches of air (just like my touring car takes this bump) the new diffuser equipped car did not leave the ground at all. Nowhere on the straight did I catch air. Steering on the sweeper was much improved. So much so I tapped the inside board several times. The flexible plastic shrugged it off. Steering on my slow speed hairpins was even improved. Mathijs; One of you guys racing in Europe should give this a try. I was very pleased with the great steering traction. Toward the end of the session they started moving a huge mound of dirt with the bobcat. Things got dusty. I crashed hard from lack of traction on one rear tire. I broke an arm, but the diffuser survided intact. The fit is near perfect on a straight front body like this Peugeot 905B. A little dremmel work is needed on the side dams of the wing. They should parallel the ground. The back edge of the wing is spaced down with some collars from body posts.
Some other wide pan tests. Try BSR pink rears. I got better forward traction than with RC4less = GRP pinks.
A little cooling duct that blows air onto the speed control really cools it down in hot weather.
John
Most late build GTP cars and our current crop of LMP Lemans cars have a front diffuser built in. This was added or improved after a disasterous series of full size cars taking flight. I recall my wide pan car doing the same in its early days. I would be in a race, In the middle of a swarm of nitro 1/10 scale, ready to make a pass early in the sweeper and the car would go airborne at about 53 mph. A lot of times it would do one backflip land on the tires and I could continue. At this point the car was stable in practice, no blowovers, but had trouble in traffic. A bump was always involved.
I constructed a series of front diffusers of varying utility. At first I did this for some high speed runs with B4maz. There is a photo series below. The first on the left was made of .030 Lexan. It increased the blowover speed by 10 mph to 63 mph. Thus it was effective, but on the track it was easily damaged and dragged the ground. I made the second from foam. It seemed to work as well as the first but was butt ugly. The third works better than either. I tested yesterday. This last model goes the full width of the front end. On a bump that launched the car with the foam model into an even glide back to the ground catching about 3/4 inches of air (just like my touring car takes this bump) the new diffuser equipped car did not leave the ground at all. Nowhere on the straight did I catch air. Steering on the sweeper was much improved. So much so I tapped the inside board several times. The flexible plastic shrugged it off. Steering on my slow speed hairpins was even improved. Mathijs; One of you guys racing in Europe should give this a try. I was very pleased with the great steering traction. Toward the end of the session they started moving a huge mound of dirt with the bobcat. Things got dusty. I crashed hard from lack of traction on one rear tire. I broke an arm, but the diffuser survided intact. The fit is near perfect on a straight front body like this Peugeot 905B. A little dremmel work is needed on the side dams of the wing. They should parallel the ground. The back edge of the wing is spaced down with some collars from body posts.
Some other wide pan tests. Try BSR pink rears. I got better forward traction than with RC4less = GRP pinks.
A little cooling duct that blows air onto the speed control really cools it down in hot weather.
John
Last edited by John Stranahan; 10-31-2008 at 03:50 PM.
10-30-2008, 04:48 PM
#338
hello, i need help on whats the recommended roleout or Spur/pinion combo for a brushed 19T motor for this car?
thanks
thanks
10-30-2008, 05:32 PM
#339
s13 evo- I have not used that combo. Someone else may help. Try a 2.37 spur pinion ratio on 6 cell, or 3.07 rollout on 4 cell. These are my 13.5 numbers which may be similar.
Orion Graphite Edition 3800 mA-h LiPo
Our small oval group has to decided to add a faster class using a Novak SS13.5 spec motor and a spec Orion 3800 graphite edition LiPo battery. I have my example in now and have tested it. Here are the reasons why the pack was selected.
Safest Chemsitry
Hard Pack
Long time in the business of LiPo.
It was not selected for best voltage or runtime which, like a previous Orion battery I tested, is well off the pack, but it has improved. The capacity compared to specs sucks. For spec racing this is of little concern. We want a battery that has a consistent voltage (and capacity) from pack to pack. I ordered a pack with Traxxas connectors; it was hard to tell what this meant. It means the pack comes with an adaptor that plugs an Orion round Plug into the battery and by short pigtail converts it to a Traxxas connectors. These adaptors are available separately. What I wanted was a battery with pigtails coming out of the hard case. I don't need two sets of plugs especially if one is an Orion plug.
Orion 3800 mA-h Graphite Edition (brand new, average of 2 equivalent cycles)
3455 mA-h with 7.05V average at a 20A discharge.
I was also able to test a 5000 Worley Parsons Cell from FMA direct which I have been torturing in the 3.5 powered touring car for over 60 cycles now.
4527 mA-h at 7.17 V average over a 20 A discharge. This is about a 9 % loss in runtime and only a 2% loss in voltage down from 7.35 V. These cells are just giving super performance over a huge number of cycles when charged at 1C. They still feel great in the TC. Here are some results from all the cells I have owned.
I had an oportunity to test my two new LiPo's from FMA direct. I also looked at some photographs and pack construction details which lead us to believe the original source is Saehan Enertech. Data on cycle life and performance of this cell is reported to me to be good. These packs are slightly long for some cars.
Cell Pro Revolution 7.35 V at a 20 A discharge. Pack temp was reasonable at 110 F rising from 70F. Capacity was 4977 mA-h. I am extremely pleased. Track performance mirrored these good numbers. This is the best average voltage I have measure for a LiPo. Certainly a larger capacity battery tends to measure better, but these are not that much bigger than max amps which were about 4200 mA-h when new. Here are some numbers on some other packs I have tested for comparison. Now if you run softsided packs and can squeeze in this very long 150 mm long pack then I would recommend this pack so far. It does have a hard plastic and fiberglass thin protective plate on the top and the bottom to give a little protection to the edges.
Now I want to tell you that I have tested a NiMH pack that had this same average voltage with powerful mod motors vs a LiPo ballasted to the same weight that only had 7.25 V average. The LiPo had a lot more punch. It just delivers the big amps better. This cellpro pack has the most punch that I have ever seen in the touring car.
AmpMax Pack A 746 seconds at 20 Amps, 4144 mA-h, 7.16 V average
AmpMax Pack B 735 seconds at 20 Amps, 4083 mA-h, 7.19 V average
Orion 3200 mA-h 2S1p Avionics LiPo when new
20A discharge, 574 seconds, 3194 mA-h, 6.87 V average
The guts of this pack are identical to the graphite edition 3200 mA-h pack.
Apogee Magnum 3800 Lithium Manganese LiPo
Pack C 20 Amp discharge, 6.94 V average , 3744 mA-h tested when new. This was my most recently purchased pack.
Pack A and B tested better when new but deteriorated to about this voltage fairly rapidly with only a few months of age and use. The capacity deteriorated to about 3100 mA-h at present after a few months of hard use.
Scorpion Lithium Cobalt Dioxide Pack 3200 mA-h
20 A discharge, 612s, 3400 mA-h, 7.19 V
This pack maintained voltage and capacity extremely well with use and time.
An improvement to the very long leads on the original pack improved this voltage to 7.25 V
John
Orion Graphite Edition 3800 mA-h LiPo
Our small oval group has to decided to add a faster class using a Novak SS13.5 spec motor and a spec Orion 3800 graphite edition LiPo battery. I have my example in now and have tested it. Here are the reasons why the pack was selected.
Safest Chemsitry
Hard Pack
Long time in the business of LiPo.
It was not selected for best voltage or runtime which, like a previous Orion battery I tested, is well off the pack, but it has improved. The capacity compared to specs sucks. For spec racing this is of little concern. We want a battery that has a consistent voltage (and capacity) from pack to pack. I ordered a pack with Traxxas connectors; it was hard to tell what this meant. It means the pack comes with an adaptor that plugs an Orion round Plug into the battery and by short pigtail converts it to a Traxxas connectors. These adaptors are available separately. What I wanted was a battery with pigtails coming out of the hard case. I don't need two sets of plugs especially if one is an Orion plug.
Orion 3800 mA-h Graphite Edition (brand new, average of 2 equivalent cycles)
3455 mA-h with 7.05V average at a 20A discharge.
I was also able to test a 5000 Worley Parsons Cell from FMA direct which I have been torturing in the 3.5 powered touring car for over 60 cycles now.
4527 mA-h at 7.17 V average over a 20 A discharge. This is about a 9 % loss in runtime and only a 2% loss in voltage down from 7.35 V. These cells are just giving super performance over a huge number of cycles when charged at 1C. They still feel great in the TC. Here are some results from all the cells I have owned.
I had an oportunity to test my two new LiPo's from FMA direct. I also looked at some photographs and pack construction details which lead us to believe the original source is Saehan Enertech. Data on cycle life and performance of this cell is reported to me to be good. These packs are slightly long for some cars.
Cell Pro Revolution 7.35 V at a 20 A discharge. Pack temp was reasonable at 110 F rising from 70F. Capacity was 4977 mA-h. I am extremely pleased. Track performance mirrored these good numbers. This is the best average voltage I have measure for a LiPo. Certainly a larger capacity battery tends to measure better, but these are not that much bigger than max amps which were about 4200 mA-h when new. Here are some numbers on some other packs I have tested for comparison. Now if you run softsided packs and can squeeze in this very long 150 mm long pack then I would recommend this pack so far. It does have a hard plastic and fiberglass thin protective plate on the top and the bottom to give a little protection to the edges.
Now I want to tell you that I have tested a NiMH pack that had this same average voltage with powerful mod motors vs a LiPo ballasted to the same weight that only had 7.25 V average. The LiPo had a lot more punch. It just delivers the big amps better. This cellpro pack has the most punch that I have ever seen in the touring car.
AmpMax Pack A 746 seconds at 20 Amps, 4144 mA-h, 7.16 V average
AmpMax Pack B 735 seconds at 20 Amps, 4083 mA-h, 7.19 V average
Orion 3200 mA-h 2S1p Avionics LiPo when new
20A discharge, 574 seconds, 3194 mA-h, 6.87 V average
The guts of this pack are identical to the graphite edition 3200 mA-h pack.
Apogee Magnum 3800 Lithium Manganese LiPo
Pack C 20 Amp discharge, 6.94 V average , 3744 mA-h tested when new. This was my most recently purchased pack.
Pack A and B tested better when new but deteriorated to about this voltage fairly rapidly with only a few months of age and use. The capacity deteriorated to about 3100 mA-h at present after a few months of hard use.
Scorpion Lithium Cobalt Dioxide Pack 3200 mA-h
20 A discharge, 612s, 3400 mA-h, 7.19 V
This pack maintained voltage and capacity extremely well with use and time.
An improvement to the very long leads on the original pack improved this voltage to 7.25 V
John
Last edited by John Stranahan; 10-30-2008 at 05:43 PM.
10-30-2008, 08:49 PM
#340
thanks john , will try that ratio out
10-31-2008, 03:27 PM
#342
Thanks. My suggestion is to get that HPI wing as it is such a good fit to the body and made of a material that bounces back into shape after a bump.
CRC World GT Spec Tires
I just got in a set of these tires pictured below. They come in a plastic box taped shut with a glued on extendable tag to hang from a pegboard peg. See the pic. Nice looking tires. Jeff and I both liked the appearance with the blue ring embedded in the tread.
I trued the tires down to 2.260 inch as is my habit these days. I noticed about .020 inch of out of round on the new tires. This is not too much. No doubt they come off a machine perfectly true but then the nylon wheel may absorb some moisture and warp slightly. They fit the Hyperdrive arbor well. No troubles here.
I have two pan cars at the moment. One wide pan (235mm) LiPo, 3.5 brushless, and one narrow oval pan (200mm), Lipo 13.5 brushless. This second car more closely mimics World GT specs. It likes the same tires now as it did with 4 cell power.
The first test was on the oval on a prepared (sugared) asphalt course. My typical tires are XXpink/purple rear and XXpink fronts on the oval. At first I had some push with the spec tires. The rear tires were great, I had good rear cornering grip, excellent zip out of the corners, so forward traction was great as well. I added some more steering throw and got the front to start gripping. The car was making good laps. I could easily have tuned out some rear grip to balance these tires perfectly.
I put on my XXPink/purple rears and it loosened the car just a tad. I could remove some steering throw and the car was making better laps. Now these are just experiments for me to guess the hardness relative to BSR tires. I guess the rears are about XXPink and the fronts are about purple or slightly less.
Better news to come.
Now I put the tires on the wide pan which I ran yesterday with BSR pink Rears and GRP purple fronts. The car with the CRC Spec tires front and back drove great! better than before. Here are some improvements. Although acceleration at the beginning of the straight was not as good as with BSR pinks, the acceleration in the last third was better. I ended up at higher speed. Cornering was just excellent. Acceleration on short straights was great. The car was less twitchy in the transitions from left to right and from coast to brake to coast than with the pink rears. I plan to switch to these spec tires on the wide pan. On the next set I will leave the rear untrued which will suit our track a little better. The fronts at 2.260 were perfect in every way.
The retail price is excellent compared to non spec tires that are available. You certainly should try a set on any pan that you own.
That front diffuser worked remarkably well. It is a keeper. I plan to run against some Nitros this weekend with the new tires and new diffuser.
pics:left CRC World GT spec tires. Right: This ain't your daddy's pan car. Rear view of the 3-link wide pan car with Panhard Bar at rear.
John
CRC World GT Spec Tires
I just got in a set of these tires pictured below. They come in a plastic box taped shut with a glued on extendable tag to hang from a pegboard peg. See the pic. Nice looking tires. Jeff and I both liked the appearance with the blue ring embedded in the tread.
I trued the tires down to 2.260 inch as is my habit these days. I noticed about .020 inch of out of round on the new tires. This is not too much. No doubt they come off a machine perfectly true but then the nylon wheel may absorb some moisture and warp slightly. They fit the Hyperdrive arbor well. No troubles here.
I have two pan cars at the moment. One wide pan (235mm) LiPo, 3.5 brushless, and one narrow oval pan (200mm), Lipo 13.5 brushless. This second car more closely mimics World GT specs. It likes the same tires now as it did with 4 cell power.
The first test was on the oval on a prepared (sugared) asphalt course. My typical tires are XXpink/purple rear and XXpink fronts on the oval. At first I had some push with the spec tires. The rear tires were great, I had good rear cornering grip, excellent zip out of the corners, so forward traction was great as well. I added some more steering throw and got the front to start gripping. The car was making good laps. I could easily have tuned out some rear grip to balance these tires perfectly.
I put on my XXPink/purple rears and it loosened the car just a tad. I could remove some steering throw and the car was making better laps. Now these are just experiments for me to guess the hardness relative to BSR tires. I guess the rears are about XXPink and the fronts are about purple or slightly less.
Better news to come.
Now I put the tires on the wide pan which I ran yesterday with BSR pink Rears and GRP purple fronts. The car with the CRC Spec tires front and back drove great! better than before. Here are some improvements. Although acceleration at the beginning of the straight was not as good as with BSR pinks, the acceleration in the last third was better. I ended up at higher speed. Cornering was just excellent. Acceleration on short straights was great. The car was less twitchy in the transitions from left to right and from coast to brake to coast than with the pink rears. I plan to switch to these spec tires on the wide pan. On the next set I will leave the rear untrued which will suit our track a little better. The fronts at 2.260 were perfect in every way.
The retail price is excellent compared to non spec tires that are available. You certainly should try a set on any pan that you own.
That front diffuser worked remarkably well. It is a keeper. I plan to run against some Nitros this weekend with the new tires and new diffuser.
pics:left CRC World GT spec tires. Right: This ain't your daddy's pan car. Rear view of the 3-link wide pan car with Panhard Bar at rear.
John
Last edited by John Stranahan; 10-31-2008 at 04:26 PM.
11-01-2008, 01:21 PM
#343
CRC World GT Spec Tires
I have put a full hour of run time on the CRC World GT Spec Tires on the 3-link Wide Pan. Thats 12 heats worth of racing with 3.5/LiPo. Wear is good. Here are some numbers. The Fronts wore down .090 inch in 12 heats worth of running or .0075 per 5 minutes. The rears wore just a bit less at .065 or .005 inch per 5 minutes. This is good for this car and should be quite a bit less with 13.5/4 cell.
The performance of the wide pan was just super today. It slaughtered all the opposition 1/10 nitros that were there. It was faster than my similarly powered TC5 today. Traction was medium-high by intent. No rubber bits on the body to indicate high traction.
I got my good wear pattern on the front and the back of the pan car with World GT Spec tires. Ripples surrounding the circumference which are most evident just after you sauce the tires. This is an indication of very good hookup. I rarely see this on the back.
Mathij(Pro Ten Holland) has been encouraging a slightly harder tire on the rear (I have been running pink rears). This one fits the bill exactly. A little harder but still grippy on forward traction. Again, Try a set of these.
Pic is of the rear suspension on the 3-link wide pan car
John
I have put a full hour of run time on the CRC World GT Spec Tires on the 3-link Wide Pan. Thats 12 heats worth of racing with 3.5/LiPo. Wear is good. Here are some numbers. The Fronts wore down .090 inch in 12 heats worth of running or .0075 per 5 minutes. The rears wore just a bit less at .065 or .005 inch per 5 minutes. This is good for this car and should be quite a bit less with 13.5/4 cell.
The performance of the wide pan was just super today. It slaughtered all the opposition 1/10 nitros that were there. It was faster than my similarly powered TC5 today. Traction was medium-high by intent. No rubber bits on the body to indicate high traction.
I got my good wear pattern on the front and the back of the pan car with World GT Spec tires. Ripples surrounding the circumference which are most evident just after you sauce the tires. This is an indication of very good hookup. I rarely see this on the back.
Mathij(Pro Ten Holland) has been encouraging a slightly harder tire on the rear (I have been running pink rears). This one fits the bill exactly. A little harder but still grippy on forward traction. Again, Try a set of these.
Pic is of the rear suspension on the 3-link wide pan car
John
Last edited by John Stranahan; 11-02-2008 at 03:46 PM. Reason: Corrected Wear Rate on the Rear. They wore even less.
11-01-2008, 01:36 PM
#344
Right Rear Steer on The Oval
I have my first report by private message by a fellow that occasioally uses right rear steer on the oval. A combination of factors might lead to its use. First you have on a left offset pod. This tightens the rear. Then there must be higher than normal traction which tightens the car enough so that it is steering poorly. Then you might try a little right rear steer to loosen the car. This is on asphalt.
Note that putting in this right rear steer causes corner exit hooking. So if this problem crops up and is unmanageble back off the right rear steer a little.
John
I have my first report by private message by a fellow that occasioally uses right rear steer on the oval. A combination of factors might lead to its use. First you have on a left offset pod. This tightens the rear. Then there must be higher than normal traction which tightens the car enough so that it is steering poorly. Then you might try a little right rear steer to loosen the car. This is on asphalt.
Note that putting in this right rear steer causes corner exit hooking. So if this problem crops up and is unmanageble back off the right rear steer a little.
John
11-02-2008, 01:44 AM
#345
It also has less rolling resistance and therefore the car has more top speed and consumes less current than with the softer rear tire.
Please note that most of us run 235mm nitro high downforce bodies which can drain 5300mAh Lipo in 5 minutes when running a 4.5 motor.
I am one of the last still running with regular Pro10 bodies (peugeot MD and HD).
Some of the drivers running Lola bodies have been experimenting with purple rears (BR) with some succes. This gives a little roll back to get car which was taken away by the huge downforce bodies.
I'll try the Spec tires when they become available here.