F1 in Schools Help - basizeland's project

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flynfrog
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Joined: 23 Mar 2006, 22:31

Re: F1 in Schools Help

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you might try only tapering the tail of the rear wheels in one dimension and get them closer to the ground

flameracing
flameracing
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Re: F1 in Schools Help

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there is no way to be sure
im just saying i think the other design is better
to anylise in further you would need to test it in a vwt or the real thing
i like salty peanuts

basizeland
basizeland
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Re: F1 in Schools Help

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@Mep I changed the channel through the car to what i think you meant by adding a venturi channel to it but im not sure whether it is what you meant and i think that i have closed it up too far.

Here are a few pics of it
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Flynfrog I will try your idea tonight when I get sometime

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flynfrog
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Re: F1 in Schools Help

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I would also do the opposite of what you just did

I would keep the peak of the nose of the car on the center line. you are creating a high pressure area with no where for the air to go.

basizeland
basizeland
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Re: F1 in Schools Help

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@flynnfrog is this what you meant by the complete opposite

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basizeland
basizeland
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Re: F1 in Schools Help

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hey Flynnfrog i quickly updated the section behind the rear wheels to slope downward is this what you meant.

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syguy
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Re: F1 in Schools Help

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I think the convergent-divergent (venturi) region is pointless - just speeds up the flow to then slow it down (even likely separate) - this will add drag. Whenever you change the velocity of a fluid you incur a penalty - drag. Having changed the direction of the flow where necessary - in your case around the CO2 canister housing and the wheels you want to transition the geometry behind the object smoothly and gradually along a streamline (i.e., like the trailing edge of an airfoil).

Bringing the rear fairing closer to the ground, as you have, seems like a good idea. The ideal shape for a car is a half airfoil - the ground acts almost like a symmetry plane, and so then you have the equivalent of an airfoil in a free stream flow - the best shape to minimize drag.

I wonder if it's worth considering a more airfoil-like shape for the front spoiler - the central portion appears to be sharp at the front and blunt at the back - to me this seems the wrong way round.

Another area to look at is the housing for the CO2 canister - maybe try making a smooth transition (fairing) from the housing opening to the nozzle. Or if that isn't possible try some slots in the housing to let flow out of the convex region.

Just thoughts.
Symscape, Computer-Aided Engineering for all

tok-tokkie
tok-tokkie
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Joined: 08 Jun 2009, 16:21
Location: Cape Town

Re: F1 in Schools Help

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As suggested you must try the infusion of glue on sample pieces. Note the mass before & after as well as the relative strength. If you can do it in a vacuum it will be much easier for the adhesive to penetrate - vacuum out all the air, dip the part & hold it there for a while, then release the vacuum before lifting the part out of the bath. Presumably you only need to strengthen the front section that breaks when the car hits the towel.
I am not certain about Q-Bond & what makes it set. Two part epoxy - very fluid as used in carbon fibre lay up may be an alternative. I have seen cyanoacrylate used to make wood VERY tough - but I can't remember where.

moil23
moil23
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Re: F1 in Schools Help

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This hasnt got much to do with the current topic but I entered this year and we got to the nationals. This was our car and as we are hoping to re-enter next year i was wondering if you could aid us with our car, this is what it looks like
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Thanks in advance for any and all advice. :D

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flynfrog
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Re: F1 in Schools Help

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basizeland wrote:@flynnfrog is this what you meant by the complete opposite

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sorry I should have been more descriptive you should try not to have a venturi area in between the sidepods this is adding drag.

the second picture is closer I would get rid of the cutout in the side pods as long weight is not a problem.

basizeland
basizeland
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Re: F1 in Schools Help

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I have removed the venturi area from the middle of the car and have removed the cutout from the bottom of the sidepods.

I am not sure whether i should remove the cutout from the top aswell and I added a bit behind the front wheels to try and clean the air from the front wheels, I'm not sure whether it is worth having these there and if they are a good thing to have should I add them to the front of the rear wheels

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flynfrog
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Re: F1 in Schools Help

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mep
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Re: F1 in Schools Help

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Yea that comes close to the idea I had. I wouldn't give up so fast with that. We should discuss this a bit more. Flynfrog basically might be right than you get a bit more drag by changing the speed of the air. But we try to regain that with low pressure zones. I would also say that’s more the reduced cross section who adds drag than changing the speed of air and reducing the cross section isn't even necessary because it was already reduced. Keep in mind that your Co2 canister also reduces cross section of the tunnel so a complete straight tunnel as flynfrog drawed it can’t be good.
Whenever you change the velocity of a fluid you incur a penalty - drag. Having changed the direction of the flow where necessary - in your case around the CO2 canister housing and the wheels you want to transition the geometry behind the object smoothly and gradually along a streamline (i.e., like the trailing edge of an airfoil).
Even with your old design you changed speed and direction of the air because you had to guide it around the wheels. What you basically want is high pressure behind your wheels and low pressure in front of them. So we apply Bernoulli’s Law who says that high speed causes low pressure and low speed causes high pressure. This could reduce the drag you already had even when it increases it on the first glance. Moreover your cars profile got more streamline and therefore reduces the possibility of a stall especially at the rear. Remember you want smooth transitions you don’t want a sudden change or a edge.

Look at the results of your simulation. You have high velocity at the rear in the channel of the car(red arrows).

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And therefore you have low pressure behind your car what causes also drag (blue area).
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Maybe its not even necessary to decrease the cross section at the smallest point further but the expanding rear section looks definitely better than your old design. Best thing would be to test it with a simulation. I would be interested in seeing the results. because this is the best way to learn for all of us.

A step back:
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You should also think about what you want to do behind your front wheels. From your simulation it’s visible that there is some air flowing from the inside of the tunnel to the outside behind the wheel. I tried to explain a few times that you should care about that area.

basizeland
basizeland
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Joined: 23 Sep 2009, 09:38

Re: F1 in Schools Help

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I will try and make the changes suggested tonight but I was bored last night so I played around with the car for a bit and I extended the side pods right down. Im not sure whether this would be any better but I thought that I would post some pics and see what you guys thought.
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tok-tokkie
tok-tokkie
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Joined: 08 Jun 2009, 16:21
Location: Cape Town

Re: F1 in Schools Help

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This is Campbell's 1935 Bluebird. It had to carry an engine so could not have the tunnel through the middle which your design has but, otherwise, I am struck by the similarity in design.

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I think your rules do not allow the sidepods to conform to the curve of the tyres. If they could then that would reduce drag - Flyingfrog?