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Old 05-29-2007, 12:01 PM   #1366
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hey jon,
glad to see you experimenting with areo on these little cars.

I tried the exact same thing way back in the day, hayday of pan cars, while running mod at the old ranch pit shop. I really don't remember any effects of this device. I think to get any real benifet, a larger under wing would be necessary, because although the scale of the car is reduced to 1/10th, the air molecules remain at 1 to 1 and thus need a larger surface to create a noticeable affect.

I did try the under wing again recently at the encino velo drome. with a underbody wing and a lexan fasten on top of the battery tray to keep the aire from entering the roff and trunk area. this is with a stock car body designed for velo racining. I also kept the rear bumper on hoping the under wind would direct the air under the bumper creating less turbulece out the back. well this worked until i got to 50 mph, then the rear started lifting. a high speed slide at 50 is not to much fun. I have gone back to an open back with a larger wing on top.

another reason I took the lower wind out is that it is very vulnerable to rear hits. my wing was destroyed when I got hit from behind at 50mph, during a spin out.

I look forward to your results, which I am sure will be better than mine.

yours,
wayne
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Old 05-29-2007, 12:37 PM   #1367
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note that I added some red text and one more photo to my previous post describing an additional ground effects part.

Wayne-Thanks for the report. I don't know if I can go much bigger but I can add side dams to hold in the vacuum. I saw these on the Nissan P35 at the rear. I imagine a lot of the Vacuum created will be spoiled by air coming in the sides. One advantage of my wing and also Christian Bresser's car from Germany is that it starts in front of the rear pod. I should be able to notice some change in steering balance if there is any effect. If you have time make a little sketch of what you did from a side view. It is hard to understand why it caused lift. I suspect it was from the part over the battery tray.

kc steringa - I'll check out the Mulsannescorner.com I think I have been there some already.
John

Last edited by John Stranahan; 05-29-2007 at 01:15 PM.
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Old 05-29-2007, 01:50 PM   #1368
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@john,do you use a cooling fan on the mamba??,i'm running the mamba in the dutch/german rc-lemans serie's and having problems with thermal shutdown!.on a rol out of 30 mm to 28 mm.this with the 7700 mamba motor.i can run it about 4 minutes depp on the temp outside and the grip on the frontaxle (understeer makes less runtime for me).and any tips for the settings(throtle curve,start power,timing?)
thanx
are the pancar racers also group-c enthousiasts???
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Old 05-29-2007, 02:42 PM   #1369
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kc steringa -The wide pan car racers use some group C GTP bodies and GT1 bodies so you might consider them group C enthusiast. I have always been as this seemed to be the ultimate race car, faster than F1 on many tracks.

I do run a Trinity fan on the Mamba and have pushed it very hard at over 35 average amps draw without a thermal shutdown in the pan car (with a 2s2P with 8000 mA-h available 7.4 Volts)

The only time it shut down was with 4s (14.8 Volt!!!) and a Novak 6.5 R. It would shut down after two laps with this setup. The LRP TC spec which I am urgently waiting on may be an improvement. Use fans, gear lower, rig up venting air from outside the body. I use the engine air intake on some of my GTP bodies to cool the speed control which on my car is mounted centered and high.

I run my Mamba with 100% brakes, max punch, linear response. I turn the brakes down to a suitable level at the radio. I don't adjust much else as the pan car is already a car in which sensitive rolling on of the throttle is required. The throttle finger is already trained.

I found the Mamba motor to be a little inefficient due to lack of a stack or core. You can run LRP or Novak motors with it. This should lower your speed control temperatures some. My motor temp went down 20 degrees with this change.

Last edited by John Stranahan; 05-29-2007 at 03:07 PM.
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Old 05-29-2007, 03:11 PM   #1370
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Somthing interesting I just found out about the Sphere TC is that it can tell you the temp on a scale of 1-12, 12 being very cool and 1 being ready to thermal. I thought I would say that because that's something that I don't think is on LRP's site unless I missed it. More specific details on in the latest RCCA magazine in the Cactus Classic article.
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Old 05-29-2007, 04:39 PM   #1371
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LRP talk about their thermal monitoring at least in their catalogue, donīt know of the website. The Sphere Competition 2007 and the Competition TC Spec is using this monitoring and it seems working very good.
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Old 05-29-2007, 04:50 PM   #1372
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Technicraft used to make rear pod plates for the 10L with a diffuser
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Old 05-29-2007, 06:12 PM   #1373
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Quote:
Originally Posted by InspGadgt
Technicraft used to make rear pod plates for the 10L with a diffuser
I used one of those way back (probably still have it somewhere). Never noticed anything performance change either, other than spur gears didn't get mangled from other cars rear ending mine......
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Old 05-29-2007, 06:31 PM   #1374
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John, can you clarify your Mamba Punch Control setting? The way you wrote above, it sounds to me like you are on the strongest level of current limiting.
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Old 05-29-2007, 07:32 PM   #1375
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Adam-I have the punch control set at 0% or disabled. I get max punch when I want it. I have drag brake at 30%. I have found that not having maximum punch available, even on a slippery off-road track, always leaves you wanting more punch on some parts of the track that may have more traction either from increased aerodynamic downforce, a slightly different surface, or inertial downforce from Upramps or landings off-road. You are better off to train the throttle finger and eyes.

Thanks for the notes on diffusers. Mine does have the advantage that it can scoop up the underchassis air and act as a wing even if the ground effects are minimal. I might see some effects from the top surface. It is not too heavy or complex at the moment. That .040 Lexan is pretty tough stuff even in the crashes. It is about 3 times the body side thickness.

Manning-If you find it post a pic.

EricRC10-I noticed that the LRP has that ability to monitor its temperature. I also note that the first generations of these controllers have lots of safetys that don't work at the exact time that you need them, and constantly irriate you at times when you don't. Stopped rotor protection did not work. I had a complete meltdown. In another case I effectively cooled the motor in my touring car and then the speed control caught on fire. The thermal protection failed. The Novak high motor temperature shutdown is the most irritating as it seems to be too low. Maybe that extra knowlege of internal speed control temp will be helpful in not relying on the safetys that don't seem to work.

Insane Speed Run
If that ground effects works then I am going to lower the rear of the body one hole and then go do an insane speed run with Nick when he is ready to test his 12s LiPo (44Volts) Castle Controlled direct drive pan car. Very direct. Wheel adaptor to the motor shaft. We are scouting suitable sites. I will run my pan in 2s2p (two 2s batteries in parallel) trim with the Novak 3.5R just to test the course and get the best line. I have spotted a place with .3 miles available, new black asphalt and a nice drivers stand right in the middle. Now what is the range on a spektrum system attached to an M8 from 10 feet off the ground on a drivers stand?

New Mamba Max Firmware
Note New mamba max firmware seems to be available version 1.09 as well as a new Castle link Program.

Note that I tried to resurrect some of my antique non spektrum radio equipment to see if the Mamba glitched with the spektrum only. Sadly I could not get any of the radio equipment working after some trouble. Old airtronics M8 stuff.

John
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Pantoura, 1/10 Pan Car, 2S LiPo, Brushless, Tips and Tricks.-ground-effects-c-resized.jpg  

Last edited by John Stranahan; 05-29-2007 at 09:35 PM.
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Old 05-29-2007, 08:22 PM   #1376
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This is the coolest thread on the whole site!
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Old 05-29-2007, 09:20 PM   #1377
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John, the Spektrum module is supposed to go 3000 Feet, according to the manual.
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Old 05-30-2007, 06:31 AM   #1378
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john,it seems that you have interferrence from the spectrum module???.iam using a futaba ff 3 pcm tranny(stone age) .without any problems.the settings you are using are almost the same as mine.i hope i can use the orion/peak motor(3.5) this month.anyone here tried this motor????.and the fan for the mamba is orderd so nomore thermel shutdowns i hope.
ps i know a couple of site's where you can download groupc/imsa race's.im not posting them here just pm me if interested
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Old 05-30-2007, 09:03 AM   #1379
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Jon,
re: the rear lift above 50, I can only think this was caused by the top wing being to small, I used a 5 inch instead of the 6 inch wing. I was hoping by placing the smaller wind further back hanging over the rear of the trunk it would cut drag, but I think it cut down force. also keeping the rear bumper on created lift. I cut it out and the car was much better except for turn 2, it would push up. that is how I hypothesized that I need more down force. and now will go to a bigger rear wing. I may go back to a lower wing by pacing a 5 inch wing upside down. It will also protect the pod from rear hits during competition.

When I ran the lower valence in onroad racing, it was to many years ago to remember what effect it had. However I do remember I had a pushing issue. so maybe it did create more down force. and at the time I was unabel to adjust the areo balance.

I got reinspired recently when i read an thread about areo and a 1/10 scale windtunnel that measured downforce etc. I believe i saw somewhere here in the rctech forums. also there is a lab that will conduct this testing, for a small fee, something like 100 buck and they would provide all the testing.

I think a windtunnel can be built easily, but a strong fan would be needed.
the car can be place on 2 digital scales to measure fron and rear downforce.

I will be running again at the Encino
Velodrome in July and I will give you a report. I am very optimistic on the cars performance.

later
wn
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Old 05-30-2007, 10:04 AM   #1380
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A lot of the rear DF depends on the body - for instance, the Peugot has great rear DF IF you cut out the two slots - which act to create a bit of vacuum and suck air farther down into the body and allow the rear "wing" (spoiler, really) to create the DF.

The older GTP style bodies are nothing compared to the newer ones. The HotBodies Toyota and the Protoform Peugot really seem to do the best as far as balancing drag and downforce.
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