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Car Action World's Fastest RC Car Challenge! What car are you going to build to break the world speed record for RC cars?

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  #201  
Old 05-21-2004, 07:06 AM
Sigurd Ruschkow Sigurd Ruschkow is offline
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You are well informed, LaPanse!

However, do not forget that Jörg used a 2250/7 and that was the lowest wind
to buy back in 2003. Today, 2004,
there is a new line of Lehner's, the HiAMP series, and with those Lehner can make a 2250/5,
and with that you WILL spinn more than 50 000 rpm under load.

It is awesome!

Now, 50 000 rpm is useles if you put that rpm on the wheels. You will 300 + mph with a 1:5 scale


Sigurd

Quote:
Originally Posted by Chris LaPanse
There would be much more load while driving a car directly (no gears) than when driving a prop directly, so you would need a 14, 15 or mabye even 16 turn motor. Besides, if it could do 160 at 25000 rpm, imagine what it could do at 50000 rpm.


Also, a 2250 DOES NOT turn 50000+ rpm under load. The 120 mph boat driven by Joerg had "only 48000 prop RPM. Still, it would be incredible to see what these cars could do.
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  #202  
Old 05-21-2004, 08:01 AM
DaFF DaFF is offline
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Lower wind, more volt is way more efficient than higher wind less volt, granted you feed those babies until they are pretty close to the rpm limit.

Don't forget as well that in a car, there is no cold water available, thus no way of cooling down the motor efficently like you guys in boat do.

The more efficient setup will run way cooler.

DFF
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  #203  
Old 05-21-2004, 02:12 PM
Sigurd Ruschkow Sigurd Ruschkow is offline
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Lower wind is what I stated.
Max rpm is 50 000.

We never water cool our stuff when racing high speed SAW.



Sigurd

Quote:
Originally Posted by DaFF
Lower wind, more volt is way more efficient than higher wind less volt, granted you feed those babies until they are pretty close to the rpm limit.

Don't forget as well that in a car, there is no cold water available, thus no way of cooling down the motor efficently like you guys in boat do.

The more efficient setup will run way cooler.

DFF
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  #204  
Old 05-21-2004, 04:05 PM
DaFF DaFF is offline
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Sorry, I am reading again my last statement and I screwed-up !

Contrary to most believe,

HIGHER wind ( or less Kv number if you wish) running under more volt is way more efficient than LOWER wind ( or higher Kv number ) with less volt, granted you feed those babies until they are pretty close to the rpm limit.

There was someone called Optimaman ( our BL guru !! ) that was explaining this in plain english.

"From Optimaman:

Biggest misconception of brushless...MUST READ BEFORE BUYING ANOTHER MOTOR


"I believe the biggest misconception in brushless motors is that "higher Kv is faster".

Yes, it's faster given the same voltage, but if you have the ability to mix and match your cells to alter voltage, you can get every motor to rev to the physical limits of the motor (the rotor breaking apart due to centripetal force).

So, you can get a slow motor to go the same RPM as a "fast" motor.

Generally "slower" motors are more efficient also so you will build up less heat which means higher efficiency - longer battery and magnet life.

Now, let's say you get a 6000 rpm/volt motor vs. 3000 rpm/volt motor. You would have to put 2x the voltage on the slow motor to get the same rpm.... but the 6000 rpm motor needs 2x the amp draw to get the same torque as the slower motor.

Because you need 2x the amp, that means you need two times the capacity battery pack...and a little more due to the fact it's LESS efficient!!!

SO, for brushless, slower motors (to a point) are more powerful because they are more efficient.

Once again, here I go again... a brushless motor is only as powerful as it is able to dissipate heat. If you put 1000 watts into a motor, and it's 80% efficient, you've got a 200 watt soldering iron - if it can't dissipate the heat fast enough, you'll destroy the motor.

If you put 1000 watts into a motor that's 90% efficient, you only need to dissipate 100 watts... So, let's put 2000 watts into this motor - at 10% loss, you're losing 200 watts to heat. Of course I'm simplifying and not mentioning other parameters... but I'm doing it do illustrate a point here.

See, you want to get the MOST efficient motor possible and simply raise the voltage to get the speed you want.

So, if you want to buy your next BL motor, go slower and higher voltage."

Read this thread:

http://www.radiocontrolzone.com/foru...d.php?t=160008

DFF
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  #205  
Old 05-21-2004, 04:16 PM
Interstate Interstate is offline
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DFF, that does make sense, but if you have the less efficient motor running on the same amount of cells (suppose that our cars have reached their maximum capacity for cells) as the more efficient motor, the less efficient motor will be spinning faster, correct?
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  #206  
Old 05-21-2004, 04:31 PM
DaFF DaFF is offline
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You are correct.

But usually, the number of cells is limited by the size of the chassis.

For this, you have two options:

1- Obviously a longer chassis !

2- Use of Lipo.

If you read what Optimaman was saying, you want to shoot for the higher voltage, less Kv, more efficient motor.

Since Lipo are 3.7 volt instead of 1.2 volt each and are way smaller, it is easy to understand the reason why Brushless + lipo is a killer setup.

DFF
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  #207  
Old 05-21-2004, 04:39 PM
Interstate Interstate is offline
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I was not aware that lipos were 3.7volts! But I still disagree that a motor with a higher RPM per volt rating would be the better option for this purpose. Why? Because these cars aaren't going to be doing a 30 min. main. They will simply be doing a high speed run. So if you've already got the torque, why not go for more revs then?
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  #208  
Old 05-21-2004, 09:24 PM
Maseeh Maseeh is offline
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Hey Steve, I am going to be entering this event because around the time it is taking place, My family is heading towards Los angeles. I want to enter my Stock Rs4 3 Evo, Which I know will not be beating any record. Would I look like a fool and a complete "Newbie" to bring it down there and have some fun with it?
Are is this for serious racers only, I hope to see ya there, Please let me know!
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  #209  
Old 05-21-2004, 09:42 PM
Interstate Interstate is offline
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It'd be a nice promo for HPI at least; you could get a true speed of an absolutely stock RS4 3Evo. Email HPI, see if they'll send you some freebies for promoting them.
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  #210  
Old 05-21-2004, 10:09 PM
Maseeh Maseeh is offline
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Alright
Of course I will be in the individual group
Interstate will you be running in this?
I was thinking about purchasing a engine, but I thought about it. I would just like to enter it bone stock, I will call Hpi tomorrow, Not really for promotions.
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  #211  
Old 05-22-2004, 12:05 AM
Chris LaPanse Chris LaPanse is offline
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Yes, that is exactly what I'm saying. I was suggesting using a high turn motor that would only turn 25000 rpm under load (32-36 cells) and use it's higher torque and greater efficiency to DIRECTLY (no diff, no tranny, no spur, just motor-axle-wheel) turn the wheels. Also, Joerg's boat WAS running water cooling-to the ESC. However, you are right in that there are no water cooled motors. I think the biggest problem with getting these things (electric ones anyway) to go fast is the ESC. The boat guys burn up water cooled controllers all the time at SAWS. There is a big cloud of smoke, and you're screwed. Now, this would be even easier to do without water cooling. Basically, the motors will be able to handle MUCH more power/current than the ESC's, so I think they will be the biggest limiting factor. Maybe some people will even run parallel ESC's-two for each motor. It will be interesting to see what happens this year with the cars. Who knows? This might turn into am annual event like the LA SAWS for boats. That would be incredible; to see boats and cars competing for the records. Finally, what will be very funny is if the boat record for RC surpass the full size prop powered boat record (205.494 mph):
In the past 4 years, the RC record has gone up at a rate so that, if it continues, it will surpass the full size record in 5 or 6 years. Cars still have a lot longer to go.
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  #212  
Old 05-22-2004, 09:49 AM
Fastcar Fastcar is offline
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G Force, you will see some drag cars... mostly funny cars becasue of the length rule that counts out rails..
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  #213  
Old 05-22-2004, 02:17 PM
Spoon37 Spoon37 is offline
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This is a cool idea..... I dont think I'll be making it tho ...from the UK Cali is a bit of a drive....lol

fastest monster would be interesting, problem is ideally a stable high speed monster would be easily over 24" a stocker TXT is 22" long.

but a monster can take alot of cells and can have the gearing to suit high speed. Its probably been mentioned as I havenmt taken the time to read the whole post, but twin motors does NOT mean 2x top speed - in fact top speed is rarely better than 1 motor, the difference is twice the torque means you get there alot faster, if you are allowed a run up/rolling start then a single motor would be better. the only exception is that with 2x the torque acting one one spur you can gear up quit liberally for more speed.

plus with a good BL motor and a heap load of cells crammed into a slammed TXT would work nicely - it would proabaly need the cells to be at least as low as the axles tho.....

I just cant get my head round the aerodynamic drag issue, the TXT tranny is too tall, so you could use an E-maxx 2 speed(better gearing for high speed too, and more adjustable due to changable spurs), but the E-trans is heavy. but evene so the trans would stick up - maybe if the 'cockpit' area was set over this it would work?? it'd probably look like a car out of the video game "rollcage" tho.

I know I am normally an advocate of the wild dagger when it comes to MT's and whilst they are low and can take 2 motors at a light wieght the gearing is just not adjustable enough to do much more than about 50+, plus it driveshafts are weak.....then again no one has ever done a dual BL dagger to my knowledge, I'm sure one with enough RPM might propel it to incredible speed.....

then again the schumacher XTR-3 will do 80(ish) MPH from its light rwd chassis and big block w/ 3 speed.....how fast could it go with a better(read higher RPM) motor and custom high speed gearing?

hmm you got me thinkin now....lol

oh and BTW chris lapense: there are water cooled motors, I have seen water cooled 800-900 size motors for boats of course - however they are not the sort of motor that would reach the sort of speed we would need.....they actually arent all that fast which kinda begs the question why bother water cooling them......they wont get all that hot when running, there just wouldnt be air flowing over them when enclosed on a boat.....


Last edited by Spoon37; 05-22-2004 at 02:23 PM.
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  #214  
Old 05-22-2004, 06:49 PM
Chris LaPanse Chris LaPanse is offline
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Let me make myself clearer. There ARE watercooled motors, just not at the SAWS. What that line in my previous post should read is "there are no watercooled motors being used at the SAWS. Also, i've seen a modded Stampede do 60, and i've heard of one doing 70. However, the MT class will certainly be interesting.
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  #215  
Old 05-22-2004, 08:03 PM
Interstate Interstate is offline
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Maseeh, If my schedule can fit it in, and more importantly, my parents let me go. I've got a super nitro that if I put in a new crankshaft, and some gearing, I could get about 80MPH. I'd like to go just to see the vehicles, and perhaps show off mine; i.e. the only thing stock are the ball bearings, most screws, and upper turnbuckles. I'd like to see how unique my super is compared to some of the others... P{retty sure I'm the only one with this engine.
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  #216  
Old 05-22-2004, 09:55 PM
Jaste Jaste is offline
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You could do it at IMS (indianapolis motor speedway). the front straight is definatly large enough, population wise it is roughly in the center of the US.
They would probably put up some money for publicity purposes too.
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  #217  
Old 05-22-2004, 11:24 PM
cretin cretin is offline
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careful. people will start to comment on the location and sooner or later, they'll have to delete posts if not the entire thread.
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  #218  
Old 05-22-2004, 11:28 PM
KMac KMac is offline
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Quote:
Originally Posted by Jaste
You could do it at IMS (indianapolis motor speedway). the front straight is definatly large enough, population wise it is roughly in the center of the US.
They would probably put up some money for publicity purposes too.

You wouldn't like the result when you hit the yard of bricks at the start/finish line.
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  #219  
Old 05-24-2004, 06:44 PM
2005Mustang 2005Mustang is offline
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Howdy

I didn't see any rule for getting assitance from another vehicle? So I guess towing your Kyosho USA-1 down the road with a Porsche doing 200MPH would be ok

Last edited by 2005Mustang; 05-24-2004 at 06:47 PM. Reason: wrong site
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  #220  
Old 05-24-2004, 11:49 PM
RacerGordo RacerGordo is offline
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that would break the size requirement... and the cost issue is up there too
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  #221  
Old 05-25-2004, 12:38 PM
CENthasizer CENthasizer is offline
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Ok, i dont have a problem with the Cali location (i live in Cal ) but looking at the article on "the need for speed" with the TC3 and the 111mph L30, i would like to quote

"Team Associated’s objectives with this car were to break through the 100mph barrier and to possibly set a new overall RC world speed record. As expected, the Team met its objectives by putting in back-to-back 100mph-plus runs. It wasn’t until the car blazed past the radar at 111mph and wiped out on the large, banked corner that they decided to call it a day. After the run, Cliff reported that the motor still had plenty of revs left and could have gone even faster if space had allowed."

IF SPACE HAD ALLOWED, this too was at the Irwindal speed way right? I just wanted to bring that up not to cause trouble, but these guys who were trying to set a speed record could have gone even faster, if space had allowed.
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  #222  
Old 05-25-2004, 03:44 PM
DualBL DualBL is offline
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EXACTLY.
that's what I had said in an earlier post, but no one seemed to notice..
-Nick
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  #223  
Old 05-25-2004, 07:58 PM
Soupisgoodfood Soupisgoodfood is offline
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Here's my idea. Get 8 7T modifieds, mount some skinny, pizza-cutter-like wheels directly on the end, set them up in 2 groups of 4 (like a train carriage) . You'd need to make custom suspension of course to allow room for the motor.

The unsprung weight shouldn't be too much of a problem considering it's just straight line speed that's important.

My only concern is the punishment the motors would take. Electric motors are fairly robust things, but do you think it would be too much stress on the bearings etc? Perhaps using more convential capped foams would be better (but more drag).

As far as electrics. Perhaps 2 ESCs, each with 32 cells.
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  #224  
Old 05-25-2004, 08:33 PM
Interstate Interstate is offline
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I think someone already said foams can't handle triple digit speeds.
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  #225  
Old 05-25-2004, 11:27 PM
Soupisgoodfood Soupisgoodfood is offline
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"Jaco Caps Tires" --> http://www.rccaraction.com/articles/need_speed2.asp
I thought capped tires were basicaly foams with rubber over the top? Or are they more like a slick with a foam insert? Hmmm... When you put it like that, they sound pretty much the same.
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