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Jason1145

Tamiya Club Official Top 10 Fastest RC'ers List

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We could work out roughly what three parasitic losses will be and estimate what might be possible.

Speculation based on estimates and guesswork is fun. We call it engineering :)

 

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2 hours ago, speedy_w_beans said:

4S.  That plus a 9400kV motor should produce a lively result or an interesting failure.

Basic math says it will go 160 mph on 4S.  The reality is something will break or the car will crash well before that.  Too much is just enough.

I've been bored with RC for most of this year; this thread really renewed my interest again with a fun challenge.

Limiting rpm for an 1150 bearing in grease is around 48000rpm. ;) No idea if you'll exceed that. It's about 56000rpm if you wash out the grease and replace with light oil.

This should be interesting to watch :)

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1 hour ago, Lawsy said:

We could work out roughly what three parasitic losses will be and estimate what might be possible.

Speculation based on estimates and guesswork is fun. We call it engineering :)

 

Nah, speculation is for scientists. Engineers build it and try it ;)

 

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3 hours ago, speedy_w_beans said:

Basic math says it will go 160 mph on 4S.  The reality is something will break or the car will crash well before that.  Too much is just enough.

Basic aerodynamics will cause most body designs to start lifting at 50 mph or less.  Better plan your aero!

We should have an achievement award for most sustained airborne time!   Flat surface only.

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On 12/16/2016 at 7:53 AM, Jason1145 said:

Just had a thought....we have a 2wd as the fastest car so far...... kind of odd as it is generally harder to keep the front end down on compared to a 4wd car.... but then again the 2wd has a lot less resistance through the drivetrain compared to a 4wd!

Also a 2wd takes a bit more room to get up to speed due to needing to ease the power on gradually for risk of flipping it..... whereas a 4wd can get up to full throttle pretty quickly which should make finding running spots a lot easier with less space required.

I beg to differ, the TA05 at the top of the board is 4wd :lol: 

2wd should have less resistance than a 4wd but it's not like it's direct drive 2wd, like in a pancar/F1. 

I would say the buggies here are having instability more because of high center of gravity and weight.

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1 hour ago, MadInventor said:

Limiting rpm for an 1150 bearing in grease is around 48000rpm. ;) No idea if you'll exceed that. It's about 56000rpm if you wash out the grease and replace with light oil.

This should be interesting to watch :)

Yes, the bearings in my car are oiled (not greased)...

38 minutes ago, firefoxussr said:

Basic aerodynamics will cause most body designs to start lifting at 50 mph or less.  Better plan your aero!

We should have an achievement award for most sustained airborne time!   Flat surface only.

That's been my experience in the past, too.  An RJ Speed Sport 3.2 pan car gets VERY light at 50 mph!  The basic shape of the Mini Cooper is such that I may have to remove the rear window to let air flow up and out of the shell.

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47 minutes ago, firefoxussr said:

I beg to differ, the TA05 at the top of the board is 4wd :lol: 

2wd should have less resistance than a 4wd but it's not like it's direct drive 2wd, like in a pancar/F1. 

I would say the buggies here are having instability more because of high center of gravity and weight.

Ah it was the DT03 was top for so long it's still stuck in my head!

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8 hours ago, MadInventor said:

Nah, speculation is for scientists. Engineers build it and try it ;)

 

 
 
 
 

Well, yes I guess we do, don't we...

7 hours ago, firefoxussr said:

Basic aerodynamics will cause most body designs to start lifting at 50 mph or less.  Better plan your aero!

We should have an achievement award for most sustained airborne time!   Flat surface only.

 
 
 
 

The thing our cars lack is any amount of front aerodynamic aids, and to be honest, I don't know how we could properly implement something without adding massive drag and remove the effect of the rear ring (which would make this pointless). I believe ensuring there is positive rake would be one thing to try, but you would need to be quite careful to stiffen the front I think. A lot of internal limiters, and an additional collar to preload the springs (front and rear) would probably do the trick... I haven't bothered with this yet as I don't think my DB01 is fast enough, but maybe if I end up getting a 3S I could test this.

6 hours ago, Jason1145 said:

Ah it was the DT03 was top for so long it's still stuck in my head!

My DT01 consistently hit 63km/h with the 3930kV motor, 17T pinion... If it didn't have two bent axels, I could drop the 5700kV and 19T pinion in that thing and aim for 90. I can't imagine stopping the DT01 from these speeds... From 80km/h, even the DB01 feels like trying to brake on ice in an emergency (doesn't everything?), however, in reality, it stops like it was driven into a brick wall. The DT01 never stopped well, though. It felt like stopping on ice from walking pace, let alone 65! I'd need another 100 metres to stop it from 90.

 

In other related news; I'm a moron.

I was chasing cars with the DB01 yesterday... It's a quiet street so this means only 1 or 2 cars per minute when it's busy (if that). This doesn't make chasing cars any less idiotic, though.

This is a momentously stupid thing to do, especially if you forget that you've tightened the slipper clutch and reduced torque reduction to better control acceleration during speed runs... Up until this point, I could gently roll onto the power and catch cars within a few seconds with ease without stressing the driveline at all. But for whatever reason, I was truly ham-fisted on the power on the next run. Maybe I was talking and got distracted, but it was certainly not intended. Through a purely accidental, yet perfect balance between initial clutch chirp, longer gearing, torque and available grip, this thing accelerated with such brutal ferocity that I nearly ran under the rear tyre of the last car I chased down, missing by 200mm or less. It was like they were joined by an elastic tow rope. I've launched this thing hard before, but this was something else entirely; the perfect fluke resulting in the perfect launch. Although it was awesome, it nearly ended my DB01. 

I stopped chasing cars at this point...

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13 hours ago, Lawsy said:

The thing our cars lack is any amount of front aerodynamic aids, and to be honest, I don't know how we could properly implement something without adding massive drag and remove the effect of the rear ring (which would make this pointless). I believe ensuring there is positive rake would be one thing to try, but you would need to be quite careful to stiffen the front I think. A lot of internal limiters, and an additional collar to preload the springs (front and rear) would probably do the trick... I haven't bothered with this yet as I don't think my DB01 is fast enough, but maybe if I end up getting a 3S I could test this.

I stopped chasing cars at this point...

g1381607942542682026.jpg

And yeah aero is only for jumping as far as I can tell on buggies.  And it'll only induce drag at higher speeds, so the best idea would be an adjustable front mounted wing.  But that seems against the spirit of this when we start adding aero pieces not found on the kit.

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Dug my old m-03 out the other day, it always seemed fast but we are talking maybe 12 turn motor, a decent esc and 7.2, going back a few years. Was thinking what to do with it, heres an idea!

j3MyIWY.jpg

 

It not the prettiest.

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In land speed racing, weight is your friend. It's considered to be "free downforce." I'm sure that is the same case with rc.

Wings give downforce, but they also add drag. Weight has little effect on top speed. 

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First test run on the DT-03 and I have issues

IMG_20161221_130608_zpsdpqezfxv.jpg

 

17T Pinion, WW2 wheels and tyres and a 4370Kv motor. No film until I get a winning run

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10 hours ago, emory70 said:

In land speed racing, weight is your friend. It's considered to be "free downforce." I'm sure that is the same case with rc.

Wings give downforce, but they also add drag. Weight has little effect on top speed. 

It's free in the aerodynamic sense.  But there is a penalty to be paid in power requirement.   That said the assumption here is the car has more power than is useable without additional downforce, be it weight or aero.   I'd argue that the drag generated at these speeds is less but would be exponentially more as speed increased: see drag curve.

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1 hour ago, Nobbi1977 said:

First test run on the DT-03 and I have issues

IMG_20161221_130608_zpsdpqezfxv.jpg

 

17T Pinion, WW2 wheels and tyres and a 4370Kv motor. No film until I get a winning run

OMG that's pure cheating chucking on big ol WW2 wheels to gain massive tyre circumference! Love it! ;p

You can eventually try the 19t pinion too right?

What issues you got? (Can't see photo at work)

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15 minutes ago, Jason1145 said:

OMG that's pure cheating chucking on big ol WW2 wheels to gain massive tyre circumference! Love it! ;p

You can eventually try the 19t pinion too right?

What issues you got? (Can't see photo at work)

only 18mph

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43 minutes ago, Jason1145 said:

Did you run a 1s lipo?!?!?!?

No checked that. The house fire when I charged it would have given me a heads up.

A few things to check and try over Christmas to see if I have something wrong. I need a program card for the ESC really. Apart from the lack of speed the £25 combo setup is quite good, very little cogging at low speed.

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8 hours ago, Nobbi1977 said:

No checked that. The house fire when I charged it would have given me a heads up.

A few things to check and try over Christmas to see if I have something wrong. I need a program card for the ESC really. Apart from the lack of speed the £25 combo setup is quite good, very little cogging at low speed.

Sorry for an almost insulting suggestion, but it happened to me while trying to fix my nephews old RC car. It was unreasonably slow and I was ripping my hair out as to why...

Have you checked the radio endpoints?  

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2 hours ago, Lawsy said:

Sorry for an almost insulting suggestion, but it happened to me while trying to fix my nephews old RC car. It was unreasonably slow and I was ripping my hair out as to why...

Have you checked the radio endpoints?  

I did not check anything to be honest, it was cold and the kids were complaining. 

It is a multi model radio so I do not think it is that but it could be a setting somewhere. I am going to try two other cars as a baseline later so we shall see.

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On Wed Dec 21 2016 at 2:03 AM, nomad said:

 

j3MyIWY.jpg

 

It not the prettiest.

I don't know, I quite like the look! 

 

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On Mon Dec 19 2016 at 10:24 AM, speedy_w_beans said:

4S.  That plus a 9400kV motor should produce a lively result or an interesting failure.

'Lively' is one way to put it!

What is the thinking with regards to voltage and brushless motors?

Keep them below the magical 100k rpm or will 4S voltage make a 9400 just go fizzzzzz? 

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Blitzer Beetle ready for another speed run attempt... a freshly charged 3s lipo, re-glued rear tyres and I've reduced the added weight on the front bumper since the last 80KPH speed run - to see if too much weight was slowing it down.... computer power cables coming in handy.

Kp45dFK.jpg

mDhQP2Q.jpg

uU29lmK.jpg

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Speed Run Entry

Blitzer Beetle, 3s lipo, 5200kv motor, 15t pinion, Dirt Hawg 2.2 rear tyres

84 KPH / 52.2 MPH

 

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Well done on the full beans run and I like the xmas special thing going on lol. Great effort. That kerb looked far too menacing lol!!

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Yeah I missed that kerb a couple times.. damp road with brutal rear wheelspin was a pain to control on such a narrow road lol... still can't make first place arrgghhh :)

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