Here are some pics and videos of a 1/5 scale brushless car going 90.1 mph
Wednesday, March 26, 2008
Team Novak headed to the 2007 World’s Fastest R/C Car Challenge (W.F.R.C.C.C.) with almost twice as much preparation as the year before. Virtually, one entire Friday was spent tightening screws and checking bearings. It’s not the epic workload you would expect to prepare fast cars. However, with just a few hours – and some off-the-shelf items – the Novak Crew was able to push their cars past the 100 mph mark several times over the day, even on repeated back to back to back runs.
So everyone is up to speed, here is a little background on the W.F.R.C.C.C. The wonderful folks at Radio Controlled Car Action magazine decided last year to start hosting the event. They rent out the quarter-mile drag strip at the California Speedway in Fontana and let us R/C nuts loose on it with whatever we can come up with. There are some basic ground rules. For example, no rockets or push cars allowed, but the main goal is to have fun at high speeds.
We kicked off Saturday morning with a brief drivers’ meeting and photo session. This year, there was an attempt to have two measuring systems. In addition to last year’s Stalker Radar System, the folks from Model Drag Racing Association (M.D.R.A.) came out to setup their timing lights. Unfortunately, some quirks prevented the system from performing, so the radar gun was used.
This year, our intention was to mainly run HV systems in our two Touring Cars. One TC is a standard XRAY T2 sedan (car No. 1) that had basically been sitting in the garage since last year. The second is an XRAY FK05 sedan (car No. 2) with a custom motor plate and a very special pinion-gear adaptor, made by Novak’s in-house machinist Dean Sowa. We also brought along our old faithful Kyosho 777 buggy with HV system installed and one Team Losi XXXBK2 off-road buggy to test some GTB/Velociti speeds.
First out was our XXX buggy, and well, it was not spectacular. We stripped a spur gear on the first run and did not have a spare with us. We shelved the car for the day.
Next, we brought out my off-the-shelf sedan and HV system using two 2S Lipoly packs from maxamps.com. Austin and Clint over at Max Amps were very helpful getting us chargers and a selection of battery packs for the event. Max Amps sells everything we used at its Web site.
The first runs are usually “shake down” runs, and we don’t max out on anything. We just want to get the car down the track at a decent speed to make sure nothing is going to go wrong. Pass No. 1 was 93 mph. We drove the car back to the start section and clocked in at 99 mph. Not bad for the test runs. We continued to add pinions to the car and ran it some more. The most important aspect at gaining speed is the car’s initial acceleration.
There is so much power being put to the ground that smooth and precise throttle application is very crucial. It’s a balance of trigger speed and how much track is left. You would think it would be easy to drive in a straight line.
Most of the day was spent fine tuning the car. We started with the same body we ran last year to 105 mph. However, it was proving problematic this year. We tossed it for a body that had some more straight-side sections. This seemed to help stabilize the car quite a bit. We crashed all our cars numerous times throughout the day, mainly in the shutdown area of the track. The racing surface of the drag strip had been recently cleaned and sprayed with VHT and had excellent traction. But the shutdown area was left untouched and, in turn, was very dirty. This made the cars very hard to control as they slowed down.
At one stage, car No.1 was destroyed, breaking the suspension, the wheel and damaging the body very badly. Luckily, we had enough parts on hand to repair it.
Car No. 2 did not fair nearly as well. We had intended to run this car from a total of 6S Lipoly. But in the shake down runs, it hit a rock and was propelled into the wall at, what I would assume was, 70-90 mph easily. The crash damaged the custom motor plate and rendered the car unusable. However, it hit 106 mph with a 4S battery and HV 6.5 motor. This car had nearly 1:1 gearing.
The crash, though bad, helped us focus on the remaining vehicles we had left. Bob was able to get his buggy on the track, and, at the normal recommended usage, it went 54 mph with a 6.5HV setup. With the 4.5 HV setup, we saw more than 60 mph.
The day was starting to wind down. We were confident in car No.1 at this stage and started to add more gearing to the motor. We were able to surpass 100 mph and were very pleased. Unfortunately, we had taken this setup to its limit. The ESC was only designed for a 4S, which was what we were using. The pinion and spur were both giving us the tallest gearing available. So, what to do? Since we work at Novak, we decided it would be OK for us to try some things beyond the recommendations of the products. The only real option we had to go faster was to increase the voltage we were using (This is not recommended and most likely will damage your HV setup).
We did this by running a 2S battery pack and a 3S battery pack, totaling a 5S pack. The HV is designed to operate the ESC and the BEC for the RX/Servo from one of the packs. The second pack simply for powering the motor. For this setup to work, you must be very careful connecting the two different voltage packs. If done incorrectly, your ESC will not run the motor properly and can damage it very quickly.
The first test of this was done with Bob’s 1/8-Scale buggy. It pushed the heavy buggy up past 72 mph. That’s a fast 1/8-Scale! The ESC was very hot at the end of the passes. Because the ESC survived, we decided it would be safe to try it in the sedan setup as well.
With an unrecommended 5S battery pack connected to our HV powered sedan, we set out to improve our speed. If you think 101 mph is fast for an R/C car, anything above that is crazy. The car lost a lot of stability and was noticeably more difficult to keep in a straight line. The first pass with the 5S was 108 mph. The back up pass was 118 mph! We attempted a third pass, but one of the RP30 tires finally let go. These tires are designed for maybe 40-50 mph so to ask them to do twice that, well, we expected them to fail. The problem was when the tire let go. It threw the car airborne and into the concrete barrier. The crash damaged most of the parts in the front end, and we didn’t have enough replacements. Panic set in. What to do?
John from HPI came to the rescue with some foam tires to try. Our confidence in foam tires is not very high because they don’t seem to have the traction needed to get up to speed. Also, we had seen foam tires fail at much lower speeds. But it was worth a try, right? What about the damaged parts, you ask? Luckily for us, we bought some Krazy Glue at the gas station in the morning and were able to glue most the parts that broke back together with no real problems.
With time winding down, we set out to back up our 118 run or at least get close. To our surprise, the foam tires were easier to drive with and performed significantly better in the shutdown area of the track. We saw a first run of 108 mph, a second of 112 mph and a third run of 116 mph. On our fourth run, one of the tires let go and sent the car skyward again. The car was fine, so we changed tires and went back out. We mustered up a final 109 mph pass right smack dab into the foam-scoring block of the drag strip. That ended our day in a spectacular fashion. Needless to say, the parts that were glued together were no longer glued together. The day was over, and everyone had put in their best runs.
In the end, our 118 mph pass was the third fastest run of the day. Nic Case and his little orange land missiles topped the charts with a 127 mph and a 119 mph pass. Nic was one of the other drivers that was consistently in the 100 mph Club. Jim “Rainman” Schauer also showed what a real dragster can do and was able make a few 100 mph plus runs.
John Schultz from HPI was also on hand running his Nitro Savage but had his electric powered PRO4 on hand with him as well. He had a GTB/3.5R Novak Brushless System installed and wanted to kill some time with it. Well, he killed a few records, too. John’s race-prepared car (not speed-run prepared) pushed well past 85 mph. His final speed was 87.5 mph using a MaxAmps 7.4v 4,000 mah Lipoly pack. He started his runs using a simple 6 cell NiMH pack that looked fairly old and raced over 70 mph the whole time. This is not official, but I believe he was the only car not using multiple battery packs. Most drivers there ran at least 12 volt setups.
Now, we cannot express how simple and easy our setup was. To be able to walk into a hobby shop and purchase each and every item we used to build your very own 100 mph R/C car is a very impressive feat. Anyone reading this article could easily do what our team did. Even simpler is the setup that Mr. Schultz has: a standard TC with a standard Novak BL System and regular packs to go 70-80 mph. The total prep time on our fastest car was only a few hours of actual work.
We must take a few moments to thank everyone that helped us with our efforts. Thank you to Bob, Charlie and Dak for going to the event and walking up and down the drag strip all day.
Thanks also to:
Jay Kimbrough for the last minute delivery of 88-tooth spur gears! http://www.kimbrough-products.com
Clint and Austin from Max Amps for providing battery packs and chargers at the last minute.
Sunday, March 23, 2008
Chris talking about his project:
First of all, my name's Chris. I posted about this speed car project on the old forum, but as it's gone, I thought I'd re-post it here. I'm hoping to break the 150mph barrier - not an easy task - so here is the "story so far" as it were on my car.
It'd get a pillow and some slippers if I were you, because you might just fall asleep lol...
My car is going to be called "LiteSpeed"...reason being, that the major emphasis is going to be put on it
being a super-lightweight machine to get the best possible power/weight ratio. She's going to be based on the Tamiya F103GT chassis *design*, albeit using only a few Tamiya parts. The F103GT is a very lightweight, RWD direct-drive 190mm chassis; think a scaled-up 1/12th scale pan car, but with touring car proportions and you're very close! This design is ideal. It's got plenty of space for an outrageous power setup, a super-efficient drivetrain design, and many other advantages which make it perfect for an insane speed car!
After doing a fair of research and brain-aching thought, I realised that it'd be much cheaper and easier to build the car from scratch using upgrade and custom parts instead of buying the stock kit. I'd only be using a small number of parts from Tamiya anyway...so there wasn't a whole lot of point in shelling out for the standard shebang. Instead (and after more research!) I discovered that 3racing make carbon-fibre chassis kit for the F103GT which looked perfect for the task of serving as the base of the vehicle. Not only does it use decent grade materials, but the price was ridiculous; under £50 for the whole kit; not at all bad. 28) The main plus-point of this kit was the weight savings of 30% over the stock FRP parts, with greater rigidity to boot. I'll be stripping the anodizing off the aluminium bits though, as blue just doesn't do it for me.
Unfortunately, a finger-twitch caused me to tragically order the kit, as well as some other bits of eBay. Such a shame, but I'll have to live with the mistake. Sigh.
Anyhoo...before you nod off to sleep, here are some images of the chassis as it sits now:
What's that transparent thing sticking out of the back? That's a polycarbonate diffuser. I won't go into super-dull details, but combined with a polycarbonate underbody that I'm going to make, it will help keep the chassis glued to the ground once she gets past 80mph. It works by causing an area of low-pressure under the rear of the car when it's at speed, pulling the chassis down without excess drag...just like on an F1 car. The underbody will keep the air flowing smoothly under the car, preventing it from getting up inside the chassis and causing aerodynamic mayhem. That probably makes less than no sense at all... but all will become clear!
Along with these parts, the bodyshell will play a crucial role in keeping the car fast, and not airborne. At these kinds of speeds a normal touring car shell just isn't up to the job, and neither are many others. Even the oval shells are useless, as many are assymetrical. I spent hours and hours, scouring the web for the right solution with a lot of guidance from aero-guro, Glypo and eventually found this gem:
It's called the "McAllister Dodge Charger HS". After some email chit-chat with the owner and a whole lot of aero-analysis with Mr Glypo, it should be perfect for the job. Turns out it's designed as a velodrome racing shell, and those cars reach 90mph...so it should be a great starting point at least.
Of course, the car won't go anywhere without a power system...and I put a lot of thought into this one (that means absolutely nothing of course, but it *should* be up to the job!). LiteSpeed will be packing a relatively massive Neu 1515 1.5D 2700kv motor with a pair of NeuEnergy 3S 4100 30/60C LiPo packs wired in series to create 6S. I opted to go for a lower-voltage, high-amperage setup as this would be lighter than a more common HV setup. Geared at a ratio of 2:1, it would theoretically high 197mph unloaded. Power output should peak at almost 4,500W, and it turns out that the car will have a power/weight ratio of 2,200bhp per metric ton. In comparison, a Bugatti Veyron has 536bhp/ton.
Because the Neu 1515 is so large - in both diameter and length - the stock motor mod plates just aren't up to the job. They aren't big enough, strong enough, have enough gearing options...and a 1515 just plain won't fit. The only reason why I have some stock plates bolted on in the above pictures is so that the diffuser can be attached for show). So...I broke out the CAD, and spent quite a few hours thinking hard and wearing my mousemat out. These parts were the result:
The first image is the motor mount plate, and the second is obviously the plate for the other side of the pod. Becuase the Neu is so long, I've had to drastically change the design of the non-mount plate so that the motor can will pass through/over it, regardless of the motor's position due to gear ratio. I've also gotten rid of the plastic bearing inserts that the stock parts use to alter ride-height on the rear axle, in favour of a fixed bearing holder (less slop). It was difficult to make room for long motor slots so that the gearing is widely adjustable without extending the car's wheelbase or it needing a modified T-plate, but I got there eventually! After which I went around trimming off every last gram of weight. Strength isn't a huge issue here, as the plates only havw to hold the large motor in a solid mesh...they won't be subject to abuse. I'll have them machined from 7075 aluminium to ensure good strength and minimum flex, though I'm not decided on where to get this done yet.
The last thing to talk about now is the Controlling Electronics really.
Key to the stability of the car will be a Futaba GY401 heading-hold gyro. This thing will help keep the car tracking straight and true under serious acceleration, greatly reducing the risk of spinning out. In turn, this will be hooked up to a fast, good quality servo. Something that's around 0.8 sec transit speed would be ideal, but I'm undecided on that yet. Speedo will probably be a Mamba Monster Max, with its huge amp rating, and the whole thing will be reigned in by my Nomadio React radio.
If anyone's been bored enough to read all that through, then thankyou! lol. Progress will be (and has been) slow due to having to spent money on other projects, but I'm really hoping to have her done by the September event.
Thanks for looking.
Litespeed looks good. I cant wait to see the results.
Monday, March 17, 2008
Video from the UK speed event practice
We visited the second installment of the worlds fastest rc car championships again to get yet more practice before the worlds later in the year! Lots of good speed passes plus one smashed at 67mph into a concreate barrier! Worth the watch! www.modellinc.com
savagefreak (chris the mechanic)
Savage K.28 2 speed - 45.52mph
Traxxas Rustler VXL - 73.67mph
X1-CR Falcon .28 CPP'd - 74.60mph
tamiya tt-01 MM'd - 66.20mph
Inferno Twin C6 Engines - 73.31mph
Inferno OS .28 - 67.11mph
Fusion - 74.00mph
Ziggys V1RRR - 82.35mph
Electric Bike - 27.74mph
Nitro Bike - 51.89mph
Great coverage from the guys over in the UK! I cant wait to see higher speeds and better weather next time.
Sunday, March 16, 2008
Chewed up spur gear after a fast pass.
Sunny broke the record for the fastest Rustler today. His setup:
Traxxas Rustler w/VXL 3500kV, MM ESC and 4S Li-Po 82mph
Finally broke the 80mph barrier... twice. Once geared 40/68 and the second time geared 40/76. I stripped the 68T spur soon after the 82mph run. I feel that more speed is possible with that set-up.
Friday, March 7, 2008
Monday, March 3, 2008
"Countryhick" in Brisbane, Australia has made this awesome electric Serpent 950. This is what he says:
Here is my setup so far
CAR: Serpent 950
MOTOR: NEU 1512 2.5D/S (2000 Kv.)
SPEED CONTROL: MGM 16018
BATTERIES: 3 X NEU 5000Mah (6s)
GEARING: (1st gear 20t P / 48t S) (2nd gear 23t P / 45tS)
BRAKE: Mechanical (standard setup)