Brabham BT46B 'fan-car', A working ground effect car! Options

[chief32s]

Outstanding.

I can't wait to see the video Graham.

ATB
Al.

[Graham Lane]

Wait no more!



This was Andy's first drive with it, so a little bit ragged. Quick though, I couldn't keep up with the camera!

[Deslotted]

Thats Dead set awesome.
Congratulations. Andi , I'm so pleased for You mate.
You had a go, You created a huge amount of interest and you pulled it off.
My Hat is off to you, that thing is shiftin'. I can't think of what else to say.

[conti_rowland]

So I want to tell you the full story.

We race at a guy called Walter Merulli's - that's his track in the video. He's an ex (and maybe future) Italian champion and he knows EVERYTHING about cars, tuning, etc. etc. Great guy.

The track is 4 lane Ninco (deeper than Scaly so I can't run the deeper guide on my old track).

On the way over (40 mins drive) I got to thinking about where this thread was going and realised that actually it must be pretty obvious to everyone that sticking a great big horizontal electrically driven fan under a slot car is going to make it faster in the curves just like a magnet.

I thought back to my initial post and realised that that is not what I want to do or what i'm about. What I wanted to achieve was a scale representation of the Brabham BT46B which had a fan in the back driven by the motor which sucked air from under the car. That's what I tried and I decided that if it didn't work I wasn't going to stick big fan motors underneath. That might be cool and i'd love to see people try it but its not what I want to do.

So I got to Walters and there were just 4 of us there playing aorund last night so I had all the time I needed to test.

I got straight on with the Brabham to get used to the drive and the track. I was putting in 11.3s laps which was disappointing as just last week over a 80 lap race I had a best of 10.17 with my Group C Slot.it Porsche.

However the inital comment from Walter who had been sceptical a week or so back when I first mentioned the project (he's a die hard traditional championship racer!), was "have you got a magnet in that". It did feel strange to drive int he corners.......

I got down though after some time to 10.4s and eventually one 10.248 before getting out the Porsche to set some comparative times. With that I lapped regularly at 10.3 before setting a best of 10.17.

I was pretty stoked actually the difference from 10.248 to 10.17 is less than 1% so I knew that a car I made with simple tools was similar to a production car well tuned.

At that point Walter looked up and took notice. He had a go. He took it straight down to the 9.7's but wasn't particulalry impressed given he can lap Group C's in a lot less than that.

I carried on testing and at a certian point took out the fan for comparative times. The car seemed quicker, it was quiter, the acceleration was better and on the straights the top speed was really fast due to the larger diameter tyres.

At that point I was beating Graham's Classic class car (Graham is about 5% quicker than me on any lap usually) and more or less equal to his Group C, losing something gradually to him but less than I normally do in my Group C. The car looked and felt fast but realistically I wasn't beating my earlier times.

Walter had a go and said it was quick and was impressed. Lapping in 9.6's.

Then we put the fan back in and on the first exploratory lap Walter shook his head and said, no its 'nettamente' (means absolutley) slower, then was shocked that his very next lap was a 9.51!!!!!

So that was enough for him, he carried on lapping for a bit in those times and then did some exploratory cornering and then stopped and said. "It works, I did a 9.5!"

And there it is folks, the car is slower in acceleration and top speed on the straights in a way that both driver and onlooker can 'feel' but the 1/10ths, 1/100ths and 1/1000ths made in every corner with the ground effect gives both me and Walter a 1% lap time increase AND the car is competitive with a tuned production car with the same motor.

I have to say I was pretty surprised. I hadn't expected it after my intial tests. The fact is that although there are the stories about how when Lauda blipped the throttle the whole car dipped on the skirts due to the suck, it seems in slot racing terms one doesn't need that much suck to help the car.

It seems to me that just creating the negative pressure under the car was enough to give it an edge in the corners which once totalled was sufficient to overcome the extra drag in the straights.

AMAZING.

Now you could say 1% is not a great deal but i'm not sure. I wasn't expecting to be a second a lap quicker look at how in real F1 cars after 200km arrive 1 second apart that's much less than 1%. If in a race of 20 minutes I did 0.1 seconds better on each lap and each lap is 10s then i'd do 120 laps to the next guys 118.8 laps. That is a large and very real advantage!!!!!

Happy racing folk........

[Slots-O-Fun]

For this effort you deserve to go straight to Slot Racing's Hall of Fame. Thank you for sharing.

[Graham Lane]

Wot, no fotos!





Look at the rubber dust it has sucked up!!!!



...and one of Walter at his.....work station!



...then he has another one where he trues tyres, cleans motors, etc.

[RichD]

The fan from a computer graphics board would be the thing to use. There needs to be a perfect seal between the intake side of the fan and the bottom intakes (avoiding the slot). It probably would be best to have the openings on the bottom of the chassis just forward of the motor so the airflow would also cool the motor. If the motor was just sitting in a vacuum it would run hot. One problem with using a motor driven fan is that you would get maximum downforce on the straights, where you don't need it, and and minimum downforce in the corners, where you do. If one was to take the motor and fan from a graphics card and use the track voltage to charge up a fairly large supercapicitor you might be able to get more downforce in the corners.

[Phil Kalbfell]

I think the graphics card fan will be way too big.

[Kustomart]

Hi there all..

Andi & Graham, great build/project, well done... I have been following the progress of this build with much intrest, and it has made me very curious...

One of the early posts, there where some photos posted, and a toy "Fan Car" was mentioned, so I purchased one of these "Fan Cars", just to see how they work..

As I did not want to interfere, or confuse your build, I thought I would leave posting my findings, until you had come to some conclusion/end, with your build/project.

I am sure you will be intrested to see how these "Fan Cars" work.. I dont think the Info, would have helped you with your F1 Car, but it might be usefull for a future project.
Here are some photos of the workings..

First of all, the bodies are made of very light plastic, the one I received looks a bit like a Hummer.


This is a view of the underside of the Fan Car, showing the Fan "Ducting" and the "Skirts".


This photo shows the chassis/ducting section and the small fan on top.


This is a good close up view of the "Fan" which spins and sucks air "up" from the underside, through the ducts and holds the car onto a flat surface.


The white strips in this photo are made of a fine but tough, cotton type material, which seems to hold the air in, even Upside down. The small grey wheels, drive the car forward.


Now this is the most intresting Photo, as it shows the "Fan Car" working "Upside down" holding itself onto a piece of Scalextric sport track, "over" the slot, even with "slots" in the bottom of the sport track. "Its not a trick shot" honest...


For the size of the fan, the suction it produces is quite amazing. The complete "Fan Car" including the body, weigh's around 52 gramm, and the Fan dia is approx 24mm. On a full charge the "Suction" lasts for about 8 to 10 mins.

Seeing how the car sticks to a piece of Scalextric sport track "upside down", I thought I would try and build a "Fan Car/ Scalextric" Hybrid Slotcar.
I will use the "Fan Car" chassis section/fan assy, and mate it to a suitable Scalextric plastic chassis (probably a sidewinder) but keep the "Fan Car" Hummer body. This is mainly due to the overall height of the lower chassis section to the top of the fan, as it is approx 30mm... Thats why I thought it would not be suitable for your F1 project, to tall.

When I start the project/build, I will start a new thread on the Forum, It should be intresting to see how it turns out.
I hope the photos are of intrest to you, and given you some Ideas. If anyone has any further questions, please ask.

All the best.. Martin De'Ath.

[alaskaracer1]

Awesome car!! Cool how you did the fan and gearing.

[gluebomber]

Excellent stuff here - again, nicely done.

There was a thread floating around on one of the forums (not sure where) that explored the larger horizontal fan concept - not at all a scale approach but still interesting.

Don't know if it was ever finished but do remember someone saying it would be D3 legal...

[chief32s]

Martin, you are one step ahead of me. I have one of these cars on order, to do exactly what you have now done, and dissassemble it and see how it works. That inverted shot over the slot shows the potential of this system (even if for an outlawed vehicle).

Great stuff. I can't wait to see what you come up with. But you are correct. This thread belongs to the excellent motor driven fan, Brabham BT46B fan car so wonderfully brought to us by Andy (conti_rowland)

Can't wait to read and contribute to the new thread.

Al.

[Mr Croker]

[conti_rowland]

Interesting indeed, it was my guess that those cars were different. I look forward to your thread too.

I've been wondering where to take this one.

I think i'll finish the car and play with gear ratios, skirts etc. And see if finally i can find a good fan.

I'll jeep you posted but anyway just want to say a huge thankyou to everyone who has contributed and was supportive.

Andi

[andi4x4]

Only just found this thread - outstanding stuff Andi ! I have to say, I had my doubts when I started reading the first page, but, you have proved and given the evidence that this does actually work !

Only one thing I would like to say -

If you have a look at a true fan/turbine type assembly, you will find that the outer edges of the blades come much closer to the inside of the round casing in order to prevent air escaping off the ends of the blades. If you could refine your design to close the gap between the blade ends and plastic ring, you may notice a small improvement. Precision is very much the name of the game with micro fans/turbines !

All the best with you future development - Here's to the first sub 9 second lap !