UPDATES!! Man I forgot I put this thread on here. Tnanks for bumping it. Here are the Industrial Designers rednerings. Next week we start laying up the frame, and milling our buck for our body....we still have to pick a body design. Take a look.
Above is my favorite, it would be a pain to make but man it looks bad
Here is a rendering of the fishbone graphic that will go on the hood. The first rendering is the color scheme we are going to do with our brands on the side.
I'll take pics when I can of our frame build up.
*Edit* I forgot two. The last one has most of our Fishing Reel Brands on it. *Edit*
[This message has been edited by Curlrup (edited 07-24-2008).]
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08:25 PM
lurker Member
Posts: 12353 From: salisbury nc usa Registered: Feb 2002
Nope we make fishing reels. However, I have friends in places that have a wind tunnel. I might send a scale model out to them and see if they could throw it in for a couple of minutes.
Your designs look really sweet but your designer is still thinking "car". The designs look like an exotic sports vehicle not a gravity racer IMHO
The soapbox racer needs to have a body more like an airplane. You really need to be slipstream without the little features that make an exotic body look cool.
This website gives one of the most successful designs and it is dirt simple in aeronaughtic terms
Alot of the success/failure has to do with surface tension, balance, and rolling resistance. I think your paper designs need to be wind tunnel compared to the more classic design to see if they are actually a superior performer. Trying to help here so please forgive the criticism.
Arn
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12:44 PM
Curlrup Member
Posts: 2590 From: Havre De Grace, MD Registered: Apr 2007
Your designs look really sweet but your designer is still thinking "car". The designs look like an exotic sports vehicle not a gravity racer IMHO
The soapbox racer needs to have a body more like an airplane. You really need to be slipstream without the little features that make an exotic body look cool.
This website gives one of the most successful designs and it is dirt simple in aeronaughtic terms
Alot of the success/failure has to do with surface tension, balance, and rolling resistance. I think your paper designs need to be wind tunnel compared to the more classic design to see if they are actually a superior performer. Trying to help here so please forgive the criticism.
Arn
No, I agree the design dubbed as my favorite has a lot of extra bends and lips on it that it doesn't need and would proably hurt the aerodynamics. I think we are going with the last design with a more aero friendly nose. That design is simple to produce, and doesn't have extra crap to slow it down. Any and all critisism is welcome on this one so thank you.
Also we have ordered high pressure 20 inch wheels that we will be filling in the spokes with urethane foam and covering with carbon fiber to make disks out of them. We should be able to make a very hard pneumatic tire with these wheels.
[This message has been edited by Curlrup (edited 07-24-2008).]
I am originally from Akron, Ohio. Home of the Soap Box Derby. I raced these when I was a little kid (late 1970's). One of the things we did was find a light weight driver (me). This gave us an advantage cause we could then strategically place weights wherever we wanted to get into the weight requirements. You are best to add weight in the back end of the car if you can. What this does is gives the car a little extra push/momentum once the hill flattens out at the bottom near the finish line. Another thing I did as a driver was... There was a very slight embankment on the side of the track. I would gradually drive the car up the embankment till I reached about 3/4 way down the track, then I would gradually come down the embankment to the end. It added a little extra speed at the end along with the weight placement.
seat-of-the-pants aerodynamics: the purpose of the bodywork is to minimize aerodynamic drag. the raindrop is probably the most efficient shape in terms of volume/surface area. look at some of the symmetrical NACA airfoils. within your length limit, go with the skinniest, lowest lift foil you can stuff your driver, suspension and wheels into. my guess is you'd want the pointy "tail" a little above the chord line, so whatever low pressure is generated is between the foil and the ground, sort of reverse lift
[This message has been edited by lurker (edited 07-24-2008).]
Jimmy that is really interesting info. Having the weight at the back is new to me. Is this track specific or do you think it would apply to most tracks?
And, if you have a rear weight bias, how much difference? or do you know?
Arn
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04:19 PM
Curlrup Member
Posts: 2590 From: Havre De Grace, MD Registered: Apr 2007
Nope this is a charity race for bragging rights and grins. There are rules I believe I posted them on the first page. Very um....loose rules. The thing is we are up against NORDAM an aerospace composites company, Spirit Aerospace, and Lufthansa. They are competeing to win and blow the doors off everyone. So we are trying to be the surprise arse kickers in this.
Jimmy that is really interesting info. Having the weight at the back is new to me. Is this track specific or do you think it would apply to most tracks?
And, if you have a rear weight bias, how much difference? or do you know?
Arn
I dont think it is track specific. I would venture to say that it would have the same affect on all tracks. The best way I can explain the weight in the back is... it's kinda like someone pushing you from behind once the track flattens out. It's been a long time since I raced and I was really young then but I remember doing a lot of testing to figure out how much weight to put where. We put some in the front and some in the back. More in the back though. We tried different lb placements and decided which one worked better. I guess it would depend on the weight of the driver. Lets say all cars w/out driver were all the same weight. Then you add the drivers at various different weights. Some may add 10lbs to the front and 30 lbs to the back while others may be 15 lbs front and 25 in the back. Its all about testing to see which works best. Determining how much weight to use and where to use it is going to take a lot of testing with a driver in the car. Basically like setting up a Indy car.
I only raced for 1 year but I remember it being a lot of fun seeing I was only 10 years old and was a race car driver. LOL
I'm of an opinion that if the elongated tear drop is the most aerodynamically efficient form then a prone driver position is the logical choice.
If you could take the driver's head out of the air stream altogether, and put the width of the driver's shoulders in the widest part of the tear drop, you would have some pretty good efficiency. Single brake on the rear wheel and aluminum arms for the front suspension and steering with a foot operated brake lever. Hmmm.....
There is also some advance in the material used for downhill ski suits. It is supposed to be more slippery than regular fabric. This could really help.
Gee this sounds like a neat project. Now I'm jealous
Arn
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11:04 AM
Jul 30th, 2008
Curlrup Member
Posts: 2590 From: Havre De Grace, MD Registered: Apr 2007
Here is a screen shot of our frame, minus the front control arms. It is going to be made from some very light weight aluminum extrusions we have here at work. Did I mention we are trying to do this on the cheap where we can? The control arms will be carbon fiber,and the body shell will be fiber glass, and carbon fiber.
I have a 1/10th scale model printing on my 3D printer right now. I figured it would be a good thing to have a nice 3D representation for fabbing. We start fabbing tomorrow evening.
I am fascinated by this!! Just one thought, which might be so stupid (after all, it is ME posting it ), but should there be NO downforce at all, because that increases drag, and perhaps apply a tiny bit of lift, to lighten the load on the wheels...it would have to be calculated to arrive at a perfect balance. I would have thought a small amount of 'lift' would actually overcome the drag coefficient caused by it, by lowering the 'weight on the wheels'...The weight would still be there, and be directed into forward momentum, unrestricted by 'contact with the ground' drag? After all, a glider going downwards in the air would do so far quicker than a glider sliding down the same angle of inclination with its wheels on the ground? In this way, you would actually be able to use gravity as a form of propulsion, rather than a braking form of energy? Perhaps even build in two winglets which could be elevated or lowered, should the lift become too little, or too strong. Nick
[This message has been edited by fierofetish (edited 07-30-2008).]
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09:52 AM
Curlrup Member
Posts: 2590 From: Havre De Grace, MD Registered: Apr 2007
I am fascinated by this!! Just one thought, which might be so stupid (after all, it is ME posting it ), but should there be NO downforce at all, because that increases drag, and perhaps apply a tiny bit of lift, to lighten the load on the wheels...it would have to be calculated to arrive at a perfect balance. I would have thought a small amount of 'lift' would actually overcome the drag coefficient caused by it, by lowering the 'weight on the wheels'...The weight would still be there, and be directed into forward momentum, unrestricted by 'contact with the ground' drag? After all, a glider going downwards in the air would do so far quicker than a glider sliding down the same angle of inclination with its wheels on the ground? In this way, you would actually be able to use gravity as a form of propulsion, rather than a braking form of energy? Perhaps even build in two winglets which could be elevated or lowered, should the lift become too little, or too strong. Nick
Interesting thought.....however would a gravity racer gain enough speed to produce enough lift to do that?
[This message has been edited by Curlrup (edited 07-30-2008).]
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11:10 AM
Curlrup Member
Posts: 2590 From: Havre De Grace, MD Registered: Apr 2007
here is the official engineer response from our project engineer and driver, about your thoughts on lift.
Can't get enough lift to counter the imposed drag. The surface area would need to be huge to lift the car and rider enough to lighten the wheels. By imposing lift you create what is termed "incident" drag and "separation" drag. For our speeds (even if we could hit 80mph) a neutral body without lift is preferred (sorry).
So there you go. Neutral is the way to go.
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11:28 AM
DtheC Member
Posts: 3395 From: Newton Iowa, USA Registered: Sep 2005
I am originally from Akron, Ohio. Home of the Soap Box Derby. I raced these when I was a little kid (late 1970's). One of the things we did was find a light weight driver (me). This gave us an advantage cause we could then strategically place weights wherever we wanted to get into the weight requirements. You are best to add weight in the back end of the car if you can. What this does is gives the car a little extra push/momentum once the hill flattens out at the bottom near the finish line. Another thing I did as a driver was... There was a very slight embankment on the side of the track. I would gradually drive the car up the embankment till I reached about 3/4 way down the track, then I would gradually come down the embankment to the end. It added a little extra speed at the end along with the weight placement.
I think that the weight in the back advantage may have stemmed from the fact that (from around here) the start, was from a raised ramp with a gate. The cars went down a small ramp. With the weight in the rear, the car had a sleight advantage. The center of mass was held higher up, at the starting ramp. It had more potential energy, to be converted over the space of the ramp. Once the ramp portion was over IMHO there was no advantage.
Thanks so much for having given my thoughts the courtesy of considering them!! I understand the reply, and am glad it wasn´t silly enough to dismiss out of hand without consideration! I wish you good luck in your project...sounds like you guys have a LOT going for you!! Nick
quote
Originally posted by Curlrup:
Nick,
here is the official engineer response from our project engineer and driver, about your thoughts on lift.
Can't get enough lift to counter the imposed drag. The surface area would need to be huge to lift the car and rider enough to lighten the wheels. By imposing lift you create what is termed "incident" drag and "separation" drag. For our speeds (even if we could hit 80mph) a neutral body without lift is preferred (sorry).
So there you go. Neutral is the way to go.
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11:58 AM
Curlrup Member
Posts: 2590 From: Havre De Grace, MD Registered: Apr 2007
Our designer started work on the body. It is a work in progress you can see the outlines of the front wheels and the shrouds that will go around them. Plus I think that scoop out of the side will be modified, looks like it will create drag. We will do some software similations on it before we start milling a buck.
Oh and teh back wheel will be enclosed the body will swoop back into a taper, and a point.
[This message has been edited by Curlrup (edited 07-30-2008).]
From the look of pic 2 there appears to be an area between the wheel and the fuselage that air can collect or compress in. It sort of looks like a piece of pie shape. Is that just the drawing or is it a design characteristic?
The reasons it is not 20 feet long are mill size, time for lay up, and transport. We want to fit in a truck bed, also our biggest mill for that buck has I believe a 48 inch travel in the y and 30 something in the x, so we need to mill the buck in pieces and glue them together. Plus I do have a budget on this and 20 feet of fiber glass and carbon fiber would cost a fortune.
Also our project engineer has already determind that all of the sharp edges on th ebody need to be removed, the scoops in the side need to be removed, and as far as the wheel pods I think we shall have to see where the designer goes with it, and tweak from there. It's comin together the same way we develope fishing reels. The designer draws it up and makes it look cool, the engineer makes it function. The design will be changing as the engineer goes through it. I do like where it is going though.
It is kinda bobsledish isn't it....Hmmmm it will change.
[This message has been edited by Curlrup (edited 07-30-2008).]
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05:03 PM
Aug 3rd, 2008
Gokart Mozart Member
Posts: 12143 From: Metro Detroit Registered: Mar 2003
Ever thought of a removable nose cone for travel? You could fab up 4-6 ft of nose cone pretty easily and attach it with small fasteners once you arrive.
Oh man I should soooooo put a badge on it. You know my car is famous around work. People LOVE my car. They would get a kick out of a badge on it. How much are those again? Like $35 from the Fiero Store?? Actually could make a custom one. I do have two cnc mills, Pro E, and skills to program Master CAM, and run a CNC mill. Something like the Zebco logo with the Pegasus. Sweet.
Oh man I should soooooo put a badge on it. You know my car is famous around work. People LOVE my car. They would get a kick out of a badge on it. How much are those again? Like $35 from the Fiero Store?? Actually could make a custom one. I do have two cnc mills, Pro E, and skills to program Master CAM, and run a CNC mill. Something like the Zebco logo with the Pegasus. Sweet.
The nose badges are $24.95 from the Fiero Store. I bet you could probably get someone to send you a decent used one for free if you put a post in the mall section.
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10:19 PM
DtheC Member
Posts: 3395 From: Newton Iowa, USA Registered: Sep 2005
Our designer started work on the body. It is a work in progress you can see the outlines of the front wheels and the shrouds that will go around them. Plus I think that scoop out of the side will be modified, looks like it will create drag. We will do some software similations on it before we start milling a buck.
Oh and teh back wheel will be enclosed the body will swoop back into a taper, and a point.
Scout out the course? A small dip might 'High Center' a racer that was too close to the Ground? Maybe make a test sled, just a 2x4 that's the same length, and a down and dirty bodged up set of wheels? Test for any unforsean bottoming out Issues? A little bottom scrape would kill a butt load of a lead?
If your 'start' is from a ramp you may get a little 'extra jump' from having a longer nose? Let the center of gravity work over a longer distance, while on the ramp?
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10:33 PM
PFF
System Bot
lurker Member
Posts: 12353 From: salisbury nc usa Registered: Feb 2002
The nose badges are $24.95 from the Fiero Store. I bet you could probably get someone to send you a decent used one for free if you put a post in the mall section.
We talked about a badge today and decided to take the Quantum biohazard logo, print it out (3D Printer) , and chrome it. Much cheaper, and much easier.
You can see the "biohazard" logo on the side of this reel here
