102 mph on the first test at the drag car race event yesterday

[Sigurd Ruschkow]

Last saturday I did my first test run at the drag car race event. I was allowed only one race during the whole day.

I got a bad start, but the grip was excellent and I raced 500m totally straight.

Speed was 163,69 km/h (102 mph).

Here is the receipt from the speed measurement equipment. My nick name is "Sigge".
Speed = "hastighet"
Time = "Tid"

http://w1.877.telia.com/~u87744635/CarProjectWeb/images/P3 040925 Scan 2.gif


Sigurd

[Speedtester]

Sweet! Nice job! I'm sure you will achieve even a higher top speed in the coming months.

Keep up the good work.

Tony.

[Piggy89373]

Excellently done!! It's good to see all your hardwork pay off.

[mgs9]

Yea. Way to go Siggie

[okalmnd]

Great job!

I can't get over the fact that they let you race a local drag strip. 1/8 mile run... too cool.

So... How was the first guess at gearing? Were you topped out or still pulling at that point? (Then again, could you even SEE it that far down the track? Where were you standing?)

[rpmmaxxed]

Great Job man. Im looking forward to see how much farther you go. KEEP IT UP BRO.

[Sigurd Ruschkow]

With the gearing we had and the motor and the nr of cells, we should have done 150 mph.
It is a puzzle still, why we did not go any faster.

The guys at the major drag car raceway are very nice guys! Hats of for them!

I positioned myself at 200m from the start position and could hardly see the car. I pushed the brakes when I thought the car was at bit pass the 402 m mark. I could not see it.



Sigurd

Great job!

I can't get over the fact that they let you race a local drag strip. 1/8 mile run... too cool.

So... How was the first guess at gearing? Were you topped out or still pulling at that point? (Then again, could you even SEE it that far down the track? Where were you standing?)

[NotWalkinBlind]

Sig, perhaps you could use a helper to see the car... the helper holds the transmitter and operates the throttle at your bidding... and you use one hand to operate the steering and the other hand to hold a pair of binoculars so you can see the car at all times.

[beetlebz]

or tripod mounted binocs. ive never seen them used, but it cant be a horribly bad idea, budget providing.

[studysession]

Good job! Just checked out the new pics on the site. Nice. ;)

[okalmnd]

Hey Sigurd! I just looked at your site again... Wind tunnel testing??!?!? and at the "The Swedish Defense Research Agency, Department of Experimental Aerodynamics." Hat's off to ya.

Honestly, I hope your work doesn't intimidate too many people and scare them away from competing. You're setting the bar pretty high. Of course, it still needs to go fast, and who know's what the others are up to...

Side note--Did you manage to record some drag forces and calculate a Cd? I'm curious what the actual numbers work out to compared to some of your CFD work. Or was the testing strictly for visualizing flow?

Can't wait for some more info. Keep up the great work.

[studysession]

I showed his sites to a few people at work and they were very impressed with your car. Cheers.

[Sigurd Ruschkow]

I have no intention to intimidate anyone. Wind tunnel testing is not
necessary. Trial and error will also work. As will hard and deep thinking.
I like to understand how things work and a wind tunnel really shows what happens around the car regarding airflow.

I am just enjoying what I do and what other people can help me with.
Wind tunnel testing was a great experience. It was my first wind tunnel testing ever.

The wind tunnel testing was mainly done for seeing what happened around the rear of the car. Would the air stay put around the curve at the rear? What about turbulence? How would the Gunry flap change the air flow?
Those questions were all answered by our test.

To do what you mention means using a wind tunnel that has a moving floor so one can check the downforce in a correct way. Not many wind tunnels have such a moving floor that can move around 200-300 km/h.

What kind of info would you like to see?


Sigurd

Hey Sigurd! I just looked at your site again... Wind tunnel testing??!?!? and at the "The Swedish Defense Research Agency, Department of Experimental Aerodynamics." Hat's off to ya.

Honestly, I hope your work doesn't intimidate too many people and scare them away from competing. You're setting the bar pretty high. Of course, it still needs to go fast, and who know's what the others are up to...

Side note--Did you manage to record some drag forces and calculate a Cd? I'm curious what the actual numbers work out to compared to some of your CFD work. Or was the testing strictly for visualizing flow?

Can't wait for some more info. Keep up the great work.

[okalmnd]

I have no intention to intimidate anyone. Wind tunnel testing is not
necessary. Trial and error will also work. As will hard and deep thinking.
I like to understand how things work and a wind tunnel really shows what happens around the car regarding airflow.
Sigurd,

Sorry to imply that you are trying to intimidate people. That was not the intention. My post was purely intended as a compliment. With the sponsors and resources you've used (Catia, CFD software, wind tunnel work) I'm convinced that your work will be rivaled by many others competing. That's all :)



What kind of info would you like to see?

Other info... Hmm... I may ramble on and get a bit long winded *sorry*

Most of my interest is in continued runs and development. Have you had any other runs? Other gear ratios? What gear ratio and tire diameter did you use on your first run?

I know you indicated gearing was targeted for 150mph--what motor RPM did you base this on? Is the motor power (3000 Watts?) based on input power or actual dyno measurement at the shaft? 32 Cells at 80 amps is roughly 3000 watts, but obviously suspect to a voltage drop and motor efficiency losses. I'm not current on the brushless technology, but I wonder if efficiency numbers can be higher than about 60-70% when pushing huge amp draw numbers.

Like you, I enjoy the work and technology behind making a project like this work. I’ve had some fun crunching numbers as a kind of “feasibility analysis” for a few ideas of my own. I’ve thought about jumping into this competition, but lack the time and resources right now. (yeah, just an excuse, I know—but there’s still some time.)

[Sigurd Ruschkow]

I have added a section on the web page that I think answers your questions.

Go to www.ExtremeSpeedElectricRCCar.com and either read the news from today or go to the Speed Theory page and click on Motor and Gearing.

If there is anything else you are interested i , let me know.


Sigurd

Sigurd,

Sorry to imply that you are trying to intimidate people. That was not the intention. My post was purely intended as a compliment. With the sponsors and resources you've used (Catia, CFD software, wind tunnel work) I'm convinced that your work will be rivaled by many others competing. That's all :)




Other info... Hmm... I may ramble on and get a bit long winded *sorry*

Most of my interest is in continued runs and development. Have you had any other runs? Other gear ratios? What gear ratio and tire diameter did you use on your first run?

I know you indicated gearing was targeted for 150mph--what motor RPM did you base this on? Is the motor power (3000 Watts?) based on input power or actual dyno measurement at the shaft? 32 Cells at 80 amps is roughly 3000 watts, but obviously suspect to a voltage drop and motor efficiency losses. I'm not current on the brushless technology, but I wonder if efficiency numbers can be higher than about 60-70% when pushing huge amp draw numbers.

Like you, I enjoy the work and technology behind making a project like this work. I’ve had some fun crunching numbers as a kind of “feasibility analysis” for a few ideas of my own. I’ve thought about jumping into this competition, but lack the time and resources right now. (yeah, just an excuse, I know—but there’s still some time.)

[studysession]

Looks good!

[DragonRail]

I was reading throught this thread and decided to post some of our test runs in prep for the Fastest RC Car challange next year.

We are testing at Piedmont Dragway, A local 1.8 mile drag stip here in NC. We are running 28 cells (undisclosed size) and a cobalt drag motor. ( these motors are used by us in IEDA Drag Races, and run 1.58 sec @ 86 mph, in 132ft)

We set the gearing for max speed at 330 ft and calculated the power we needed based on our dragsters.

So far we have been able to reach 127mph at the 330 mark. While this is a good test run, I think 135mph + will be needed to win the challange next year.

Good luck

Bob
www.ieda-dragracing.com
www.rcdrags.com

[Sigurd Ruschkow]

Bob - 127 mph in only 330ft is a real accomplishment! 127 mph on any track length is a real achievement!

28 cells in a drag car. What kind of drag car do you use?

and 28 cells on a cobalt motor!! I used 10 cells on my cobalt motor and that drag car screamed!
Do you use a standard cobalt motor that is normally used for 6-10 cells? or do you have a modified high-voltage one?


Sigurd

[DragonRail]

Sigurd,
I build custom Drag motors ( DragonFire motors (http://www.bndrc.com/dragonfire.asp) ) They use a 6 magnet design that produces the most torque of any elictric rc motor in the world.

The arms are custom wound and bound with kevlar.

We use these motor in RC Drag Racing with 20 cells. I use a Grand Motorsports Dragster chassis and custom 1300 batteries.

Our speeds in 132' are 86mph with ETs in the 1.5 to 1.6 second range.

Check out www.rcdrags.com to see some of the videos of the killer fast cars.

Bob

[e_lm_70]

I have added a section on the web page that I think answers your questions.

Go to www.ExtremeSpeedElectricRCCar.com and either read the news from today or go to the Speed Theory page and click on Motor and Gearing.

If there is anything else you are interested i , let me know.


Sigurd

Hi Sigurd,

You mention : "radar guns only measures accurately only when the moving object to be measured is coming straigh" , so you are assuming that you are making error on mesuing the speed...

Can you try to mount a GPS in the car (I guess 80g will not cause any arm in your set-up) ... in this case you will have a more accurate result (if you enable the tracing mode you can see also how was progressing the acceleration), and you could compare with the speed gun result.

e_lm_70

P.S: I hope the 4g limit acceptable for most GPS is not a problem :rolleyes:

[studysession]

Give the guy some credit. He does not need to mount any GPS on the car. The GPS's are not 100% accurate either.

I think that is asking to much of Sigurd myself. JMO

[e_lm_70]

Give the guy some credit. He does not need to mount any GPS on the car. The GPS's are not 100% accurate either.

I think that is asking to much of Sigurd myself. JMO

????????

A wrong angle on mesuring the speed with the speed gun means 50% error if you are 45 deg from car line ... and 100% error if you are 90deg from car line ... so the possible error is huge !

The GPS state to be extremly accurate on speed mesurement:
GPS accuracy:
Position: < 15 meters, 95% typical*
Velocity: 0.05 meter/sec steady state
And there is no space for make human error on using it !

If the calculated speed should have been 250km/h but you just get 175km/h, it would be interesting to know if there is a huge error on the mesurement, or there is a quite big errror in the estimation.

Considering that a 1/10 brushed dragster is stated to be able to go over 200km/h ... my guess it is that there is a possible mesurement error ...

e_lm_70

[Scomp87]

geez y'all are so ignant.

okay, so if sigurd is taking the velocity from angle @ (@ is the angle) , then sigurd's velocity on the radar gun is actually less than the actual.

real velocity = H
velocity on gun = a
angle = @

a = Hcos@

since the cosine of @ will be less than 1, unit circle propeties people. Then (a) is less than (H)

so even if sigurd does have an error, he actually wants a greater error, it means he's actually hitting higher velocity!

[Sigurd Ruschkow]

My guess the car was doing around 200 km/h.

Next year we will try to have some kind of roof above the race track so the angle will be very small,
and thus we will get a very accurate speed of the car.

A GPS is useless at these speeds and these accelerations. Most boat racers who race SAW know that. The problem is not the accuracy of the GPS
it is the short time intervall the GPS has to measure the steady state speed.



Sigurd

geez y'all are so ignant.

okay, so if sigurd is taking the velocity from angle @ (@ is the angle) , then sigurd's velocity on the radar gun is actually less than the actual.

real velocity = H
velocity on gun = a
angle = @

a = Hcos@

since the cosine of @ will be less than 1, unit circle propeties people. Then (a) is less than (H)

so even if sigurd does have an error, he actually wants a greater error, it means he's actually hitting higher velocity!

[studysession]

Sigurd -

regardless of what everyone else here posts - I would still be excited with your result. Good luck!

[Chris LaPanse]

The best way is a speed trap where it has two sensors a short distance (~10 feet) apart, and it calculates speed based on time between the sensors. That is how they do it in drag racing.

[e_lm_70]

A GPS is useless at these speeds and these accelerations. Most boat racers who race SAW know that. The problem is not the accuracy of the GPS
it is the short time intervall the GPS has to measure the steady state speed.


Strange,

I use my Garmin 201 for mesure speed up to 190km/h and I didn't find any problem (used inside a real car).

The only limit of the GPS it is that they make a mesurment every seconds, so you need to keep the top speed for 1 second (better a couple) in order to get an accurate result. In case you can't keep the top speed in a sustained mode, then you get as result the best avarage speed inside a second time frame. That could be different then the top instant speed.

If you have a GPS around, it would be nice to use it for compare the result from the speed gun.

Anyhow, sorry for the little bit out of topic ...

And me to I'm very curios to hear news about your improvements.

e_lm_70