World's Fastest R/C Car, anyone?

[Billfred]

Alright, so my interest in FIRST started with my interest in remote-controlled cars. (I'm working right now on building the longest, but that's another thread.)

I picked up a copy of Radio Control Car Action, and on the back page they issued a challenge. Build the world's fastest R/C car. For the rules (IIRC--I'll make sure later that I'm not missing anything), anything goes, as long as it's under two feet long, have some sort of 3D cockpit (something that it looks like a driver could sit in if it were full-size) uses driven wheels for propulsion (sorry, rocket guys), and has an FM radio with a fail-safe. (I'm pretty sure they'd live with an IFI system, even if it wasn't the best way of doing it.)

It'll be sometime after 6/1/05 out at Irwindale Speedway.

Now, with all of us fielding robots with four-speed eight-motor shift-on-the-fly gearboxes, you just KNOW that a couple of FIRST teams could whip up a mind-blowing car. The electric world record is 111 mph on 24 cells and a two-turn brushless motor.

Anyone mildly interested?

[Astronouth7303]

I don't think many of us have expieriance with fast, just powerful. (Correct me if I'm wrong). But I'll help through IM, if you ask.

[Elgin Clock]

The electric world record is 111 mph on 24 cells and a two-turn brushless motor.

Anyone mildly interested?Is that speed scale mph?? Like how when new remote controilled cars come out for the holidays they say it has a scaled speed of 60mph.

Or is 111mph, an actual speed. Did a remote controlled car really go 111mph?
Wow.. That's 1.85 miles per minute..

Whoa!!!

[Astronouth7303]

It's like the land speed record. you point it and hope for the best! :D

[greencactus3]

Is that speed scale mph?? Like how when new remote controilled cars come out for the holidays they say it has a scaled speed of 60mph.

Or is 111mph, an actual speed. Did a remote controlled car really go 111mph?
Wow.. That's 1.85 miles per minute..

Whoa!!!
yes, thats not sclaed speed. its actual speed... a 10:1 rc car scaled at 60mph is pretty slow i think.. not sure this is correct, but around 6mph??
that would be slow.
some rc cars go 70 outta the box..
how hard would it be to control 111mph rc car? i wouldnt even want to try it.
actually, i would, but id probably destroy it...
and rc cars at toys r us and whatever that come out at holidays are definitly NOT fast. get a nitro car... wish i had one...


and i am deeply interestred..

[Tristan Lall]

Try a 600 cc motorcycle engine, converted to run nitromethane! I could see 200+ HP being possible. (But the conversion probably wouldn't be easy....)

[ZACH P.]

Try a 600 cc motorcycle engine, converted to run nitromethane! I could see 200+ HP being possible. (But the conversion probably wouldn't be easy....)


Lol, do you have a source for the nitromethane? 'Cause if you do...

[Tristan Lall]

No, I've never had the chance to get my hands on any. Nor do I know how such a conversion would be done--but I would imagine that a motorcycle drag racer would have something to say about this.

[Bcahn836]

That car would be very unstable. If you hit a pebble at that speed the car is going to roll, flip and cartwheel and never stop.

[Astronouth7303]

That car would be very unstable. If you hit a pebble at that speed the car is going to roll, flip and cartwheel and never stop.
Not to mention the nitro going boom.

[Billfred]

Well, that's the advantage of doing it at Irwindale: they keep that sucker clean!

And yes, that's straight-up, just-like-you-drove-it-in-your-car 111 mph.

Personally, I don't think it'd be that hard for FIRST teams to adapt to speed. I mean, we build for torque, since that's what's required to move a hundred-pound mobile goal. Change the gearing up, and while it won't be able to push much, it'll scream like anything.

Although the charges against the Nikko cars and the like would make for an interesting challenge...world's fastest Nikko, anyone?

[team222badbrad]

Yes that speed record is actual speed. This hobby is very expensive first off! Today many rc cars are very complex and yet simple pieces of fun! Some RC cars have 3 speed trannies and very small high powered engines.

I would not attempt to use the Mini Innovation First contoller (EDUBot). First off this would be very heavy! Second their is no need to use one! Third if your car crashed at 50 MPH is would no longer exist.

My RC truck (tmaxx) costs $400 bucks for the truck. Not to mention the batteries and chargers another $40. You also need other support equipment.
The fuel alone cost $23 a gallon. Imagine paying that much for it at the pump! yikes!

If you need anything just let me know.

Here is my truck. It goes 40 MPH out of the box. www.traxxas.com

[Ryan F.]

Drill motor, no gearbox, battery, and a set of wheels. Need I say more?

[sanddrag]

Drill motor, no gearbox, battery, and a set of wheels. Need I say more?Not enough torque. Need I say more? Actually, I shouldn't jump to such a conclusion. You never said what size wheels you were using. But assiming you wanted to go 112 mph, you would need a wheel approximately 2" in diameter on the 19670 rpm drill shaft. Now, at stall the wheel would only be able to exert approximately 7.9 lbs of force on the ground. As motor speed goes up, torque goes down. So, I reckon moving at 112 mph (near 19670 rpm), you will have very little torque, certainly not enough to counter the air resistence.

Aside from that, I am fully willing to help with this project in any way possible if anyone will be working on it in the southern california area. While I've been fading from the hobby in recent years, I do have many years experience with RC cars and have 9 cars , both nitro and electric and have cutsom built frames before. This sounds like a fun challenge and I'm certainly willing to work with anyone who wishes to enter.

[Matt Reiland]

Now, with all of us fielding robots with four-speed eight-motor shift-on-the-fly gearboxes, you just KNOW that a couple of FIRST teams could whip up a mind-blowing car. The electric world record is 111 mph on 24 cells and a two-turn brushless motor.

Anyone mildly interested?
Hmmmm, My last car, (Kyosho Inferno Kani II) was pretty darn quick (~50mph with the OZ 2.5hp engine) but it was actually an off road car with a high stance and only a single speed. IF you wanted a really fast car, here is what one would have to do.

1.First, ditch the IFI control system, it is too big, too short of a range, and not useful for an RC car. Get a PCM radio that can cut your throttle if it gets out of range so you don't kill the person 3 blocks down the street from you when it goes by in a blur.

2.Create a Custom aluminum chassis based on a comercially available RC road car probably 1/8 scale which already hit over 70mph
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXGAJ2&P=0

3.Take two .21-.26 race engines (~2.5-3 hp ea) and link them together like the Ofna Titan Twin. http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXFJB9&P=0
I can't see how you could get that much horsepower out of electric for even a fraction of the weight with the motors and batteries. (Take a look)
http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXEPH9&P=0
OVER 3 HP at 39,000 RPM!

4.Take the Automatic 3 speed from the Kyosho Mad Force http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXCGR3&P=0
and send it into a small custom high speed gearbox driving the front or rear wheels, such that the gearing uses the motors on the top end.

5.Tune in the steering servo for extremely dull steering input so that a tiny movement at 100mph doesn't launch it 30ft off course.

6.Add in a well supported body with some downforce so it doesn't take off like a jet.

If you can do all that, my guess is it will be pretty fast!!!!!

[sanddrag]

Matt you make it sound so easy. :) It will be quite difficult to make all those components work together but it can indeed be done. As for the horsepower of that engine, I've read sever articles claiming that the way manufacturers come up with that rating is different between each company and it is not a uniform system of measurement/testing. Your 6 step plan would make a pretty fast car. How fast? I don't know. One thing is that nitro engines can not run at WOT for too long or they'll break the con rod or sieze or blow a gasket or whatnot, not to mention possibly overheat. But it might be possible for just getting to top speed and back down really quick. It would depend on the gearing. Also, the speed and power you can get on them depends largely on several factors such as air temperature and humidity, fuel composition, etc. You would need some really good tires and a body and components because of the forces involved with such high speeds.

Even with all the challenges, I would like to try this.

What does everyone think of a dragster style car with just a really fast electric motor with a pinion, an axle with a spur and wheels, a _______ load of batteries?

Or would a pan car type car be better or would a sedan?

Is larger better or no?

So many questions.

[Max Lobovsky]

Try a 600 cc motorcycle engine, converted to run nitromethane! I could see 200+ HP being possible. (But the conversion probably wouldn't be easy....)
needs to be under 2 ft long

[Max Lobovsky]

Not enough torque. Need I say more? Actually, I shouldn't jump to such a conclusion. You never said what size wheels you were using. But assiming you wanted to go 112 mph, you would need a wheel approximately 2" in diameter on the 19670 rpm drill shaft. Now, at stall the wheel would only be able to exert approximately 7.9 lbs of force on the ground. As motor speed goes up, torque goes down. So, I reckon moving at 112 mph (near 19670 rpm), you will have very little torque, certainly not enough to counter the air resistence.

Well, there is a really simple explanation to why you are almost definitley wrong in your reasoning. Unless the drill is much less efficient in (input/output and output/weight), then a direct drive configuration is probably precisely what you are looking for. If a motor, batteries, and chasis can go at 111 mph, then a motor with an output/weight ratio anywhere near the ones used in the 111 mph car would, in at least some configuration, be able to travel at 111 mph also. Using your calculations, we see that to achieve this with just a drill motor and a wheel, we need to actually use larger wheels and therefore less force at the wheel because that is using the free speed which is no where near the peak power output (and therefore a very bad output/weight ratio). Using the formula for drag in a non-compressing fluid:
D=(1/2)*CD*A*r*V2
we see that the drag force of such a car (assuming it is a sphere with radius 10cm)
= (1/2)*(0.5)*3.14*(0.1 m)2*(1.2 kg/m3)*(49.6m/s)^2 = 23.2 N or ~5lb.

The drill at max power is at ~10k rpm therefore requiring about 4" wheels and outputting about 7.9/(2*2) = ~2 lb. (divided by 4 because double size wheels and half stall torque). $@#$@#$@#$@#, maybe I should have made those calculations before starting to write this :). Seriously though, I think this result shows that is reasonable to have the drill motor going at 111 mph on direct drive, especially because of the highly overestimate drag (a sphere the size of a basketball?).

[sanddrag]

I somewhat screwed that up didn't I? :D :o Of course you can never get more power out of a motor and gearbox than you can out of just the motor itself. But what I was thinking is that the drill motor wouldn't have enough power to reach those kinds of speeds. But perhaps it is indeed possible. The RC motors spin at more like 28,000 rpm but the drill motor I believe has more torque.

Anywhoo, we can sit here and engineer this all day but I think untill one of us gets off our chair and starts making it we'll never know if its possible.

/me rummages through old RC parts :)

EDIT: /me kicks self for selling carbon fiber pan car chassis I once had.

[Max Lobovsky]

Anywhoo, we can sit here and engineer this all day but I think untill one of us gets off our chair and starts making it we'll never know if its possible.

Haha! Yes! That's the real engineer attitude! I wonder what sorta power source you can use that can give you such a high power/weight ratio (not energy/weight, lithium would suck in this case). Considering it runs for only a few seconds, maybe even capacitors?

[Billfred]

Nah...it has to still be able to run afterward.

The 111 mph record run, IIRC, was done on about 24 sub-C cells, all wedged into an Associated L3O. So I don't think that using Sub-C cells is a death sentence...unless you're dealing with some insane high voltage (like a hybrid car's batteries).

[Tristan Lall]

needs to be under 2 ft longI thought someone would bring that up.

If I really wanted to be picky, I'd point out that there was no (stated) restriction on how wide the thing was--so mount it in a transverse arrangement.

Also, if you slightly tilted a standard v-twin or a very compact 4 , you should be able to make it fit within 2'. Problem solved.

And if that's too big, use an 85 HP competition go-kart engine. (Uses 100 octane racing fuel, no less, so it's a little safer....)

[ebmonon36]

I think that the speed record is for cars using the rc car race people sanctioned (im forgetting the acronymn) parts so I think go cart engines are out. The one that set this record if I recall correctly was build by Associated employers and could have gone much faster if it hadn't crashed into the wall at the track they were racing it on. :)....it would put my Kyosho Turbo Ultima (circa 1987ish) to shame.
Eric

[sanddrag]

it would put my Kyosho Turbo Ultima (circa 1987ish) to shame.
Eric You ever heard of a Panda Danny Thomson's Stadium Racer? Probably not. It has a little Thunder Tiger .10 engine adapted for the truck. It is the most POS RC car I have ever owned. Its brake is a piece of cork bonded to a brass strip that is bent over by the servo and rubs on the clutch bell. I bought it because it was only $50 brand new in the box and it was old and rare. It has a really cool body though...

Ah, I love RC cars. They are so much fun sometimes.

Just a quick story on the importance of failsafe mechanisms. I was once driving my Traxxas Nitro Stampede with my JR XR3 FM radio. The AA battery holder in the radio had a crack, but once it was put in the radio it all seemed to sandwhich together okay and it still worked fine. Well, this one particular day, I had the engine all tuned up for maximum performance. Just as I was making a full speed run dead center down my street, the craked part of the battery case in the remote breaks even further, the transmitter batteries lose contact with the terminals, the radio loses power, and the servos stay in their WOT and dead ahead positions and the truck takes off screaming dead down the middle of the street at 30+mph. It goes a full block until it comes to the intersection where it crosses the street and runs head on into a curb at full speed. But that is not all. It bounces off and makes a right and goes up the other street. At this point, I can't see it because it is no longer on my street but I can hear it's engine still screaming at WOT. After it goes up a block, it hits a curb again, somehow makes a U turn and starts heading back down the block it went up. Finally the front end is falling apart and it veers to the right back into the curb it hit the first time where it finally flips over. I thought that when flipped over, it would run out of gas and the engine would shut off, but no. From being so shaken up, the fuel is all filled with air bubbles and the engine is runing in an extremely lean condition. As I ran up to it, one tire was stuck against the curb but the other was in the air and it looked like a pizza cutter it was spining so fast. It must have been stretched out to 10" in diameter. The engine was screaming at such a high pitch and rpm I thought it was going to blow. It was the loudest sound I had ever heard in my life. When I was finally able to shut off the engine by putting my thumb over the air filter, there was the greatest silence I had ever heard in my life. Luckily, it somehow managed not to hit any houses, parked cars, mobile cars, animlas, or people.

And that my friends is why it is important to have failsafe mechanisms.

[Scooter]

If it were me, I'd take a .46 size engine off of one of my r/c airplanes and strap that in with a little centrifugal clutch, and gear it down....just a little....these motors have decent torque and a uber high top end rpm of 20k rev/min. If you put that to a big set of wheels, you'll have one heck of a car. I would also do the steering so that it has a very small range of movement, thus increasing the controlability of the car (you could also set in dual rates on your x-mitter).

Whaddya think? Could it work?
-Bill

[Greg Needel]

just FYI here are the offical rules of the challenge

http://www.rccaraction.com/rc/news/car_challenge.asp


and here is the set up for the car that has the current record

http://www.rccaraction.com/rc/articles/need_speed.asp


I aslo found this RC fourm with alot of information in their thread

http://www.radiocontrolzone.com/forums/showthread.php?t=167401


my brain has been running circles around this project since i heard about it

[sanddrag]

If it were me, I'd take a .46 size engine off of one of my r/c airplanes I think Thunder Tiger already makes a truck with a .70 helicopter engine. It goes fast, but not 112+ fast. Perhaps that's because it is a monster truck and geared for torque.

But an airplane engine is an interesting idea. They rev almost as high as the car engines but come in much larger displacements. It may be difficult adapting a clutch though.

[team222badbrad]

It may be difficult adapting a clutch though.

I would not bother even using a clutch! I would just make the thing direct drive. You would just have to implement some kind of remote kill switch (micro servo?)

If I were to build anything I would definitaly built a car with an engine not a motor!

Batteries are too heavy

[Maxzillian]

Oooooo, it's about darn time they decided to hold an official competition. :) I've personally been on the r/c scene for the last 5-6 years and have seen some pretty darn crazy creations. The following being two of my toys I've hand built... although the latter has been in the works for 4 years and still isn't done and the former has a little touch up work that needs to be finished such as strengthening the rear suspension and making battery mounts to hang the packs off the side of the chassis to keep the center of gravity down.
http://www.mtsquad.com/phpbb2/viewtopic.php?t=116
http://www.mtsquad.com/phpbb2/viewtopic.php?t=59

Anywho, I can't see a drill motor propelling one of those cars past 111. The brushless motor used in the record holding car would hit RPMs past 60,000 and still have power to spare. Hence why the latest craze on the r/c scene has been brushless motors. Compared to brushed motors they're over twice as powerful, more efficient, and more reliable. However, being a nitro guy myself I always ignore the new electric gadgets. ;) Without a doubt, if you were to build a speed car, you'd need a on-road racing engine. Considering that the newest ones touch 3-4hp and still managed over 35k, I think they'd have enough power. The problem is taking that power and harnessing it in the most efficient of ways. So, and I almost hate saying this, the best drivetrain would be a belted drivetrain. With kevlar belts, it'd just barely be reliable enough to handle that much power. However, I personally think that a 2 wheel r/c vehicle would be the way to go. If you think about it, it's the most aerodynamic, stable (at high speeds), and efficient chassis design to use considering how little rolling resistane there would be. The only problem would be keeping the bike upright during the run while keeping it in a straight line. Perhaps a gyro to control a set of balance weights and some wires hanging off the side to act as training wheels? Either way, that's my two cents on the subject.

[Salik Syed]

forget piston engines :D
grab yourself a micro turbo prop engine...and connect it to the drive shaft.... search for wren micro turbines and you'll find it.

[RogerR]

they said that turbine power is allowed, and that made me wonder...what if you used a solid fuel rocket motor to spin a turbine? the only issue that i wonder about is rule #6

6. The vehicle must remain operable after its speed runs. Sacrificial motors or power systems that are inoperable after a run are not permitted.
would a spent rocket motor be considered a "sacrificial motor"?

the whole question is hypothetical, since i wouldn't know how to go about making this...i'm obviously out of my element.

[sanddrag]

Oooooo, it's about darn time they decided to hold an official competition. :) I've personally been on the r/c scene for the last 5-6 years and have seen some pretty darn crazy creations. The following being two of my toys I've hand built... although the latter has been in the works for 4 years and still isn't done and the former has a little touch up work that needs to be finished such as strengthening the rear suspension and making battery mounts to hang the packs off the side of the chassis to keep the center of gravity down.
http://www.mtsquad.com/phpbb2/viewtopic.php?t=116
http://www.mtsquad.com/phpbb2/viewtopic.php?t=59That 6x6 is really awesome. Here's my coolest ride. http://team696.org/images/Mvc-018s.jpg I custom made the tube chassis. I did it when I was really young and I don't have it together anymore. The frame cracked in a few places over the years (I raced it you know) and I wanted to put it back into its original form. I also made a tube rockcrawler style chassis for my Clodbuster that is all together but I never got around to doing electronics and paint.

[Bcahn836]

Our school actually has a R/C car club, one of our teacher mentors is really into these cars. They race in the school parking lot and go off road with the T-Max then go back inside fix them and do it again. All of the members bring their own cars and just have fun. And most of them are on the robotics team which is cool.

[Maxzillian]

Sanddrag: Thanks. :) I love the sand rail. Personally I've wanted to build one for some time now but I never did get around to collecting the right parts for such a project. Now I can't tell from the picture so I'll guess. Is yours based off a rc10?

I wish our school had a r/c car club, but there really isn't enough inthusiasts in our school let alone the entire community to support such a thing. I personally know 3 people who have r/c cars, but none of them do it very often.

[sanddrag]

Sanddrag: Thanks. :) I love the sand rail. Personally I've wanted to build one for some time now but I never did get around to collecting the right parts for such a project. Now I can't tell from the picture so I'll guess. Is yours based off a rc10?I'm glad you like it. I was going to put an interior of sort but I could not find properly scaled seats and didn't have the expertise to make them. It was based on Losi XXT.

As for this world's fastest challenge, I took a look around the Tower Hobbies website and here's what I came up with. The HPI Proceed looks like a very suitable platform for such a high speed car. I found that the Trinity Novarossi and Sirio racing engines have a claimed maximum RPM of an astonishing 44,000 and around 3 hp. With one of those engines and the optional gear set, the Proceed would have a theoretical top speed of around 134 mph. Now, in realityit would probably be considerably lower, more near the record of 111 mph. If there is some way to get another engine into a Proceed or make it use a 3 speed (like from the Kyosho Mad Force), it is possible to make a potentially wining car. Or maybe there's even a way to get two two speeds in series for four but I have a feeling for such a large space three would be sufficient. One disadvantage of the Proceed is that the engine is mounted transverselly, making it difficult to run a twin setup. Maybe something more like an 1/8 scal off road buggy chassis where the engine is inline and it would be easier to add a second one. Ofna has a car called the Ultra GTP that is like this but made for on road. I think Ofna even has a monster truck with two engines called the Twin Titan. Perhaps the engines could be swapped out and it modified for on-road racing?

The only bad thing about this contest is that RC cars cost so dang much and I haven't even heard of any sort of monetary prize. (Of corse having an RC car that goes over 100 mph would be a prize in itself)

[Maxzillian]

Honestly, the car shouldn't need a ton of power. The way you can get around that is by making a car with great aerodynamics and very little rolling resistance. So basically a car with narrow sedan tires or even foamies and a body that is as low as possible. However, if you do want to go ahead with the twin engine idea, I'd have to agree on using a 1/8 scale buggy. They have plenty of room for such a setup and I've seen it done several times before (the most memorable being Greg Vogal's Nitro USA-1 with twin engines and the ability to hit 67 mph). :)

[sanddrag]

(the most memorable being Greg Vogal's Nitro USA-1 with twin engines and the ability to hit 67 mph). :)OMG I remember that! You read RCCA? That truck was so awesome. And he used those HG lexan shock bodies - it was like right when they came out. He was such a cool guy, does he still work for them?

Anyone remember Chris Chianelli? (sp?) He used to do the "Back Lot" He then went to work for DIY on his own RC TV show and now I guess he has his own line of Megatech products. He was awesome too. Too bad no more Back Lot though. Wow, I have so many old issues of RCCA. Probably like 100.

[Billfred]

OMG I remember that! You read RCCA? That truck was so awesome. And he used those HG lexan shock bodies - it was like right when they came out. He was such a cool guy, does he still work for them?

Anyone remember Chris Chianelli? (sp?) He used to do the "Back Lot" He then went to work for DIY on his own RC TV show and now I guess he has his own line of Megatech products. He was awesome too. Too bad no more Back Lot though. Wow, I have so many old issues of RCCA. Probably like 100.
They still have backlot--just not his backlot.

(On the other hand, I guess you could compare the two to a 196X Pontiac GTO to a 2004 Pontiac GTO. But still...)

[team222badbrad]

Speaking of RC are any of you going to purchase the new Traxxas Revo when it comes out? I would but I just dont have $500 to spend.

http://www.traxxas.com/REVO/

[Billfred]

If Dave won't say it, I will--that's pimp.

Thing is, I'm an electric guy. Nitros just are too much of a headache for me, between the noise, the smell, the cleaning, the tuning, the fuel...yikes!

When they come out with an E-REVO, I'd probably be all over it. (Is it Revo or REVO?)

[Maxzillian]

Sanddrag: yeah, I have just about every magazine RCCA has put out from 1997 to 2002-03, but I stoped subscribing after then since many of the articles they put out now is just recaps of old articles. RCCA used to be a great information source, but lately it hasn't been up to par. I only wish Chris was still a part of RCCA, his backlot sections and articles were simply perfect. As for the REVO, I'd love to own one, but I'd rather build the truck myself. ;)

[team222badbrad]

This is an interesting article I found in todays local newspaper:

http://www.timesleader.com/mld/timesleader/8950817.htm

Posted on Fri, Jun. 18, 2004

Earning a living is hard, sure, but this is ridiculous

By MARK GUYDISH

WILKES-BARRE - "Yeah," Walter Letanski said on the store phone shortly after the robbery. "Your mother does have a broken wrist and an ankle sprain. They sent her up to get a cast. It's broken in two places."
The snatch-and-run saga that left Karen Letanski sprawled on the ground outside the family store happened with lightening speed, but the effects will last for months.

"Three guys in their 20s came in," explained Walter, owner of Walter's Hardware on Coal Street, on Thursday afternoon. "Two were at the counter talking to my wife. The third guy was over in the hobby department."

Walter was near the back of the store. His wife grew suspicious when one of the men talking to her made eye gestures, apparently to the man behind her.

That man then grabbed a gas-powered, remote-control model truck and ran out the door, with Karen following. The two other men charged out behind her, hitting her in the back and knocking her down. "I heard my wife scream," said Walter, who would not disclose his wife's age.

It was not going to be an easy escape, though.

A customer in the parking lot saw the commotion and followed the three in his vehicle as they ran up a side street, hopped in a car and sped off. The customer continued to follow, Walter said, until the culprits went the wrong way on a one-way street.

One of the three men had been in the store before, about a month ago, Walter said. He came in with another person - not one of those who robbed the store Thursday - and that person tried to buy a model car with a check. But a call to the bank revealed the check was no good, so the men left.

The previous visit, the bouncing check and the parking lot witnesses gave police "a lot of good leads," Walter said, increasing the odds the men will be caught. He praised Wilkes-Barre police for their speedy response.

The toy the men stole? A Horizon Hobby HPI Nitro monster truck worth $400. If it's not recovered, that's money out of Walter's profits. The insurance deductible is more than twice the car's value.

But that's not important, of course. His wife is. He fears she'll be hobbled by the injuries for months.

Which also makes work at the store harder. She's part of the staff, along with his kids. "We really have a family business here," he said, his voice trailing off for a moment.

Then he picked up again. He described the three robbers as white men of average height - 2 or 3 inches shy of 6 feet - and thin.

"It would have been better if it had been my son," at the counter when the thieves struck, Walter said. "They wouldn't have knocked him down."

A customer interrupted, asking for help and guiding Walter to the boxes of gas-powered, remote-control vehicles.

"My son wants one with four-wheel drive," she said.

Obviously, he wants to get his the honest way.

Mark Guydish, a Times Leader staff writer

Walter Letanski, owner of Walter's Hardware on Coal Street in Wilkes-Barre, recounts the theft of a remote control model car Thursday afternoon. Two of the three thieves knocked his wife down when they ran, breaking her wrist.

[Billfred]

This is when you just let them go. I mean, a swiped Savage will hurt you, but so will a few grand in medical bills.

Let them win the battle--then win the war.

[trhgammer]

have any of you thought of using dual egines on a car because you could probaly get twice as much speed out of them. You could make a tank that is twice as big so that the car stays balanced. But hooking them both up could be difficult. But the only problem I can see is weight because more weight the slower the car can go. Oh and I was wondering if any one has checked out the traxxas jato if so could you tell me anything about it's performance.

[sanddrag]

There's a couple cars on the market with dual engines, but I think they are all monster trucks. The hardest part is getting them both tuned to run the same. More weight doesn't necessarily mean less speed, it means less acceleration.

[santosh]

Dual Engine that reminds me of the Jep hurrican 2 hemi engines. But back on topic. Who won the competition this year/got the fastest car?

[team222badbrad]

I have not seen the Jato on the track, but I have looked at the truck before it was released at a hobby show. It looks pretty cool, but I am not sure this would be the best vehicle to mod for speed.

How about going for a bigger engine rather than running 2 engines?

The only vehicles I have seen with twin engines are monster trucks such as the Giga Crusher.

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXHJB2&P=ML

My Losi LST has a .26 engine weighs 13 pounds and goes about 39 MPH.

I am sure you could get the 5 pound Jato to go much faster with a bigger engine, the only downside is that you would have to greatly mod the transmission, if not build your own. ;)

Find the most powerful engine with the highest RPM.

The other problem with the Jato is that there is not much room for a bigger engine as far as I can see, I could be wrong here.

The truck seems pretty balanced also, however, the engine is mounted to the left side of the truck.

[mechanicalbrain]

the fastest rc i believe was a corvette (the car not a model) running on remote control!

[Jeff K.]

I was reading this older issue of Extreme RC Cars and in the "Racers' Rides" Section, which was the cars of the subscribers. One guy had built a 1/8 on-road car that started as an Inferno 7.5 using a mill, lathe, and CNC machines. It has a Hacker C50 Maxx motor and 12 cells powering it. It also has a custom 3-speed gearbox and has been radared at 92 mph.

Maybe instead of nitro, howabout dual brushless?

[sanddrag]

Maybe instead of nitro, howabout dual brushless?Great idea, but may I suggest tripple brushless? :D

[Jeff K.]

Great idea, but may I suggest tripple brushless? :D

LOL OOH Shweeeet:D

Geared way up at like, almost 2:1...but it would have little to no torque and would take a long track to reach top speed...Or am I wrong? I don't know much about brushless, but I have a 10 turn motor on my Team Associated TC4 with a gear ratio of about 5:1...I may be wrong but it takes just 15 feet to reach top speed.

I'm thinking about maybe going brushless soon, does anyone have like, any reasons why I maybe shouldn't?

[sanddrag]

I'm thinking about maybe going brushless soon, does anyone have like, any reasons why I maybe shouldn't?Cost! They aren't cheap. But they sure are smooth and reliable.

[Kyle Love]

Don't they have racing ones that go around 120-150?

[sanddrag]

Don't they have racing ones that go around 120-150?Maybe scale mph but certainly not real mph. The fastest so far is Cliff Lett's 114 mph run. The fastest out of the box is a claimed 80 mph which is this car http://www.racing-cars.com/usa/products.asp?recnumber=292

[mechanicalbrain]

i guess my remote controlled corvette doesnt count? :( i seriously wish i had video.

[Jeff K.]

Maybe scale mph but certainly not real mph. The fastest so far is Cliff Lett's 114 mph run. The fastest out of the box is a claimed 80 mph which is this car http://www.racing-cars.com/usa/products.asp?recnumber=292

I was reading it. It's not 80 mph "out of the box."

For Top Speed it says:


Top Speed: 80 mph (With optional gearing U2567)


So well...technically it's not 80 mph right out of the box, but it can reach 80 mph and possibly even more if you play around with the gearing. But Schumacher makes great onroad touring cars.

[ShaneP]

Wow, I didn't realize that so many of you guys/gals had RC cars. They are truly wonderful machines, that can carry the same technologies as the full-sized scale racing cars.

I subscribe to RC Car Action and RC Nitro. Both are great mags. However, I haven't heard too much about the speed contest latly. Last I knew it was delayed until after June and hadn't heard too much about it after that.

I did have a few ideas for breaking the speed record, but didn't have the resources to make them come true. Of coarse there is always the route of taking and boat load of batteries and hooking them up to a low turn brushless motor. I would say Lithium polymer batteries would best suite this application. But, it would be rather interesting to see a nitro break the record.

Have any of you seen a tether car in action? They are capable of reaching speeds of over 200 mph. That is realtime speed, not scale. In other words just as fast as some of the fastest full size cars on the road these days. the catch is that they need a "push start" to get going, but once they do they rocket up to 200mph in not much time.

Here is a vid of them in action(scroll down almost to the bottem of the page):
http://www.radiocontrolzone.com/cars/video.asp

If you were to take either a brushless motor or a nitro engine to get a tether car configuration up to speed, that would take place of the human "push start." You would need the primary drive system to get the tether configuration up to about 80mph before it could take off on its own. 80mph is how fast the "push start" gets the tether car going to before it is on its own.

Hopefully the weight of the tether configuration in the car wouldn't weigh it down so much that the primary drivie system couldn't get up to speed(80 mph). It sounds logical, but this would call for a great R & D in aerodynamics and chassis distrabution to accomplish this. Anyone confused? :D

I have always been interested in this hobby, and because of it I had already had a good resource of info about robotics. I say this to encourage people to look into this hobby. It is not only to have fun, but 3/4 of the time you find yourself working on them, matinenceing them, or learning about them, rather than running them. It definately is a worth-while experience.

[Mr.G]

Lithium polymer batteries are great. They have twice the power per weight of other batteries, but they cann't supply the high currents needed for that type of sprint race. They are best suited for endurance type racing.

[MikeJ675]

With the requirements, there's a lot of possibilities...

40" length is a lot to work with.

Some of the motors commonly used in robot combat could be 'interesting' if used properly.

S28-150 Magmotor

This is a smaller, lighter version of the popular S28-400. Same diameter and powerful magnets, just in a shorter, lighter package! And would you believe a whopping 3 horsepower from a 3.8lb motor?

3" Diameter, 4" long
1/2" diameter shaft with 1/8" keyway, 1.75" long
24V (can be run higher)
3 horsepower
1970 oz-in Torque
Max current 285 Amps
82% Efficiency
6000 rpm
3.8 lbs
Neodymium magnets

There have got to be fun ways to use one or two of these...

For the truly insane-
ETEK motor by Briggs & Stratton

This is one of the most powerful DC motors available. There is nothing like it out there. Many of the most powerful spinner robots out there have been using this motor with great success (including Nightmare, Son of Whyachi, Moebius and many more). WARNING: this motor is NOT an ordinary motor, and should be handled with GREAT care. It is very capable of serious power and should always be completely secured before applying any power to it.

24V to 48V (has been run up to 72V)
72rpm per volt (3456rpm @ 48V)
20.8 pounds
7.91" diameter
5.64" length
7/8" shaft with 3/16" keyway and 3/8-16 Tapped center
Torque constant: 1.14 in-lb/Amp (0.13 Nm/Amp)
Max motor current: 330A for 2 minutes

could you imagine the power of this thing at 72v?(estimated 15hp at 48v)


Assuming a new supply is found, the AME D-pack motor is amazing in power to weight and cost to weight(the only downfall being the HUGE stall current)

12v stats(they will run at 24v)
Angular-velocity constant: 592 rpm/V
Peak power: 4.78 hp
Stall current: 1240 A
Stall torque: 2770 ozf·in

with any of these, though, the problem is getting the power to the ground. High traction tires and some creative gearing solutions could easily provide the means of getting to the speed you want.

[sanddrag]

Even direct driving a large 6" wheel on the Magmotor wouldn't get you into the recordbooks. You'd have to actually gear it up.

[Andy A.]

My prediction for the flat out, fastest car at the track will be a factory sponsored 'car'.

It'll probably be a 2 foot long dragster looking deal. Power will be from 1-2 high voltage brushless motors, possibly hand made or modified specifically for this car. Battery packs will be made up of sub-c cells or smaller, but not Lithium chemistry. Nickle will carry the day. The tricks will be in reducing rolling friction and weight as far as possible, and maximizing gearing. The winner will have two gears. A relatively low accelerating gear that could top out around 60-80 and a taller gear, 1:1 or higher to push over 115 mph.

High speed stability should be interesting. The crashes will be pretty spectacular. I don't expect the winner to waste much weight on a brake. How to stop it?

The winning independent car will probably look a lot like the factory winner, only slower.

-Andy A.

[mechanicalbrain]

one thing i thought was cool was a college built a all electric car that tops off at 300 mph! :ahh: i saw a film it was absolutely amazing!

[Jeff K.]

Battery packs will be made up of sub-c cells or smaller, but not Lithium chemistry. Nickle will carry the day. The tricks will be in reducing rolling friction and weight as far as possible...

-Andy A.

I'm just wondering, why not Lithium Polymers or Lithium Ion battery packs? Lithium is the same weight or less than NiMH or NiCD for almost twice the ampheres. It's lighter so higher top speed...or is it just because of the safety involved with Lithium?
I have a friend that runs a micro with Lithium and he always has to be careful with it. I think it's because he's scared of them catching on fire or maybe blowing up.:ahh:

[Andy A.]

I'm just wondering, why not Lithium Polymers or Lithium Ion battery packs? Lithium is the same weight or less than NiMH or NiCD for almost twice the ampheres. It's lighter so higher top speed...or is it just because of the safety involved with Lithium?
I have a friend that runs a micro with Lithium and he always has to be careful with it. I think it's because he's scared of them catching on fire or maybe blowing up.:ahh:

Ever wonder why lithium catches on fire so often?

Lithium based batteries do have great energy density. The problem with using them on an R/C car like this is that they are very limited in how much current they can deliver over a short time.

NiMH don't have those same restrictions. Current draws can get pretty high with out starting a fire. This is good when your using low turn motors with high speed gearing.

-Andy A.

[mechanicalbrain]

yeah does anyone know what the Milliamp per minute output for lithium batteries compared to similar batteries of different composition.

[sanddrag]

yeah does anyone know what the Milliamp per minute output for lithium batteries compared to similar batteries of different composition.If they were of different composition then they wouldn't be similar right. :D But maybe you mean similar voltage and capacity.

[mechanicalbrain]

If they were of different composition then they wouldn't be similar right. :D But maybe you mean similar voltage and capacity.
Yes i do, but thank you for pointing out my lack of ability at articulating my thoughts clearly at 2 in the mourning. :D

[sanddrag]

Yes i do, but thank you for pointing out my lack of ability at articulating my thoughts clearly at 2 in the mourning. :DI don't mean to find flaws, I just want to make sure I understand. :)

So anyway about the lithiums, the only thing I really know about them is that they are much more expensive and are used in long period low current applications like cell phones.

[mechanicalbrain]

im almost positive i read an article about a company making a lithium power hand saw (im bad with tool names. its the one that is used for wood cutting. it has a flat area that the blade extends from, and the blade is cicular. looks like a jigsaw.)

[Cory]

im almost positive i read an article about a company making a lithium power hand saw (im bad with tool names. its the one that is used for wood cutting. it has a flat area that the blade extends from, and the blade is cicular. looks like a jigsaw.)

A circular saw? Most portable power tools use NiCad batteries.

[Jeff K.]

Well...
A 7.4V 4950 mAh LiPoly packs can be the same size as a 7.4V 3300 mAh NiMH pack, maybe a 3800 mAh because they're the same size too, but the LiPo pack will be a few grams lighter.
http://www.maxamps.com/contents/media/l_Lipo%20VS%20GP.jpg

I know that the chance of catching fire because of the large amount of current going through the system. They have been rated at around 50 Amps discharge, while most NiMH packs are rated at 20-30 Amps discharge. But really, the LiPo packs are used just to save weight and for longer run times because a motor usually sucks just 25-30 Amps and so a 4950 mAh Lipo will last probably 1.303 times longer than a 3800 NiMH. A NiMH pack would probably last ~15-20 minutes, while a LiPo would last 20-26 minutes. Once I really think about it...A LiPo wouldn't actually mean much in this kind of competition as it's not going to be endurance. It's more or less just a sprint race to see the top speed, but a LiPo of lesser ampheres could be used just for weight.


And Mechanicalbrain, are you talking about a table saw?

[mechanicalbrain]

hehe. yeah a cirular saw and im 94.2376% (to the dot) sure it was lithium and had a super long battery life which is why it was in a article in the magazine. it had to do with new lithium battery technology. ^ thanks thats exactly what i was wondering!

[Mr.G]

Here is the best battery info I have ever read on Lipo Batteries. I fly a micro helicopter and this is the best battery supplier. The Doc is long, but very good reading especially for our group.

http://www.fmadirect.com/support_docs/item_1115.pdf

I hear FIRST was going to us Lipo's next year in robotics. I guess the are now wanting to compete with robot wars and have fire and smoke. JK

One other thing Lithium is that stuff your science teach used to keep locked up because is self ignites in the presence of Oxygen. Ours cut a small piece off and made it ignite, then a girl freaked out and they ended up evacuating the whole school. It was a little bigger piece then normal. He got in big trouble for that one.

[Jeff K.]

One other thing Lithium is that stuff your science teach used to keep locked up because is self ignites in the presence of Oxygen.


Oh yeah, I forgot about that. We actually did something similar in Chemistry...okay so we watched in on TV, but he dropped a small piece of Lithium in a petri dish of water and when it had being quite an exothermic reaction. All of the elements from Group 1A will react the same way, Sodium, Potassium, Rubidium, Cesium, and maybe Francium...I'm not sure about the last one though, does anyone know if it is or not?

So is its reactiveness the reason why they are a safety hazard if one of the packs were to get damaged and the Lithium was exposed to the air?

[mechanicalbrain]

I wanted to post these two things for general amusement and i thought this would be a good thread although neither is directly related.
One: the worlds fastest car clocked at over 300 mph.
http://www.buckeyebullet.com/

Two: found this and thought it was just plain cool. Its a turbine jet powered gokart.
http://www.big-boys.com/articles/jetcart.html

[Don Wright]

Correction:

the worlds fastest electric car clocked at over 300 mph.