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Author Topic: Frontal Area / Cd numbers  (Read 24078 times)

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Offline robfrey

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Re: Frontal Area / Cd numbers
« Reply #150 on: May 14, 2019, 02:05:20 PM »
Like I said. I like the way you think BIG!
I also like your approach about designing the whole car, then deciding if you will actually build it. Not many people think this way.
You are certainly welcome to hang out in our pits this year. After seeing more closely on how the game is played, it will probably influence your design a bit even if it is witnessing what we do wrong. You can just as much from that.
Tom Burkland influenced our design quite a bit just from his emails about what he was experiencing driving down the salt. It was invaluable.


Rob Freyvogel
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Offline Simspeed

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Re: Frontal Area / Cd numbers
« Reply #151 on: May 14, 2019, 06:45:27 PM »
Like I said. I like the way you think BIG!
I also like your approach about designing the whole car, then deciding if you will actually build it. Not many people think this way.
You are certainly welcome to hang out in our pits this year. After seeing more closely on how the game is played, it will probably influence your design a bit even if it is witnessing what we do wrong. You can just as much from that.
Tom Burkland influenced our design quite a bit just from his emails about what he was experiencing driving down the salt. It was invaluable.

Rob Freyvogel
#496
AA/BFS

Thanks Rob...thanks also for the pit invitation; I'd be honored to visit with you just as I will be with others like Stainless who have offered the same during Speed Week.  I'm anxious to see first hand what it takes to be competitive on the salt.  I'm sorry if what I said in any way infers that I think you or anyone else is doing it wrong, I don't believe that for a minute.  I only have fanciful ideas about going fast based on my limited understanding of aerodynamic theory and time spent behind the welding mask...which admittedly was many years ago.  I believe what I believe but in no way do I mean to be disrespectful to those who know what they know and have proven it through the years.  Thanks...

Offline Simspeed

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Re: Frontal Area / Cd numbers
« Reply #152 on: May 14, 2019, 06:58:32 PM »
Here's a body redesign using the contemporary drooped nose look.  I like Sparky's take on yaw effect from the taller slab sided nose.  This is a proven design that when molded out of carbon fiber should be structurally sound hanging off the nose of the chassis.  I think tubing hung out to the nose will flex too much under load in this application.

Offline Interested Observer

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Re: Frontal Area / Cd numbers
« Reply #153 on: May 14, 2019, 07:03:07 PM »
However enamored you are with flashed refrigerant cooling systems, to avoid designing into a dead end corner it would be good to verify that the system will remove the required amount of heat and do so at the required rate.

Offline Simspeed

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Re: Frontal Area / Cd numbers
« Reply #154 on: May 14, 2019, 07:07:24 PM »
However enamored you are with flashed refrigerant cooling systems, to avoid designing into a dead end corner it would be good to verify that the system will remove the required amount of heat and do so at the required rate.

Right you are IO...start with a design and test before committing it to steel and aluminum.  Thanks...

Offline jacksoni

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Re: Frontal Area / Cd numbers
« Reply #155 on: May 14, 2019, 07:51:06 PM »
I think there are a lot of possible improvements here. I think you know most of those here are Bonneville /SCTA racers and think in terms of SCTA rules for running in venues governed by them. FIA/FIM may well be way different and allow other formats of construction. A streamliner in the former setting requires minimum 4 wheels (can have more) but they do not need to be in rectangular configuration. Your vehicle is looking more like a motorcycle streamliner. As has been stated if your eventual goal is just a wheel driven vehicle run somewhere for the ultimate wheel driven record, you are not bound by SCTA rules. Bolivia comes to mind.
Jack Iliff
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Offline Simspeed

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Re: Frontal Area / Cd numbers
« Reply #156 on: May 14, 2019, 10:04:54 PM »
I think there are a lot of possible improvements here. I think you know most of those here are Bonneville /SCTA racers and think in terms of SCTA rules for running in venues governed by them. FIA/FIM may well be way different and allow other formats of construction. A streamliner in the former setting requires minimum 4 wheels (can have more) but they do not need to be in rectangular configuration. Your vehicle is looking more like a motorcycle streamliner. As has been stated if your eventual goal is just a wheel driven vehicle run somewhere for the ultimate wheel driven record, you are not bound by SCTA rules. Bolivia comes to mind.

I watched the video series of the Ack Attack in Bolivia and that track is something else for sure.   Most likely that's where new ultimate records will be set.  Logistically it's a nightmare.  The team sponsor better have deep pockets because it's going to cost a ton to race there.

Your point about non standard wheel locations Jacksoni crossed my mind too when I considered the design for V.4.0.  I toyed with a four wheel diamond pattern which worked well with the body restrictions but the chassis layout for that just didn't work out for the small cross section. Stretching the current design allows for a third pair of drive wheels which would give a 3000 hp Kw equivalent requiring 4 more generators and probably a third 4 rotor IC.  Far fetched stuff but doable with a big enough bankroll.  Thanks...

Offline Peter Jack

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Re: Frontal Area / Cd numbers
« Reply #157 on: May 14, 2019, 10:29:41 PM »
I'm just speculating here (That seems fair game in this particular thread!  :-D) but I would think that the more drive axles you put adjacent to one another you're going to run into ever diminishing returns unless you can add significant weight so there is no loss of tractive force. The more weight you have, the more difficult it becomes to accelerate. It's just another thing to think about. Drive at both ends is probably a better approach but it's difficult with the shape you're attempting to maintain.

Keep thinking!  :-D :-D :-D

Pete
« Last Edit: May 14, 2019, 10:35:33 PM by Peter Jack »

Offline Peter Jack

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Re: Frontal Area / Cd numbers
« Reply #158 on: May 14, 2019, 10:40:26 PM »
How efficient can electric motors and generators be made in comparison with conventional mechanical driveline components? I really like the idea of rotary engines as long as I have a really good hearing protection system if I'm around the vehicle.  :-o :-o :-D

Pete

Offline Peter Jack

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Re: Frontal Area / Cd numbers
« Reply #159 on: May 14, 2019, 10:45:51 PM »
Now you've got my mind working, and that's dangerous. I would think this vehicle might benefit from a very limited travel suspension system such as elastomer donuts to aid with traction. Just another comment from the peanut gallery.

Keep everyone thinking. It's good for the mind!

Pete

Offline Simspeed

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Re: Frontal Area / Cd numbers
« Reply #160 on: May 14, 2019, 10:52:43 PM »
How efficient can electric motors and generators be made in comparison with conventional mechanical driveline components? I really like the idea of rotary engines as long as I have a really good hearing protection system if I'm around the vehicle.  :-o :-o :-D

Pete

From what I've read of mfg. specs 97 to 98% efficiency is top of the line Peter.  That's pretty amazing really in my opinion.  When we consider gear losses and the like for mechanical drive systems I'd think there's not much difference really.  If anything the electrical drive systems may be more efficient all things considered.  

Yes, I wanted to drive from either end but like you say its tough to do with this envelop.  As with anything there are diminishing returns in adding more drive wheels. Tracking wheels one behind the other will also lead to traction issues I'm sure.  That's why I wanted to stagger them in a diamond pattern but I couldn't figure out how to make that work in this application.  Thanks...

Offline Simspeed

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Re: Frontal Area / Cd numbers
« Reply #161 on: May 22, 2019, 07:01:55 PM »
With research input from Don (Raceengineer) I've studied the angular diffusion issue with the long canopy.  I've come to the conclusion the canopy shown previously is infeasible so another solution is needed. The images below show a shielded cockpit where a real time camera system is used to show forward vision during a run.

I found a company (https://www.orlaco.com/)that manufactures HD vision systems for all types of real time commercial applications including forward and rear view cameras.  MirrorEye is used in the trucking industry and forward vision systems are designed for earth movers and forklifts.  There are lots of other mfgs of course but this company has component systems available that could work in this application.

This is also the body geometry that I'm having a CFD analysis done on.  I'm going test the CFD with and without the lower skirts to see what the difference is.  Any thoughts?

Offline tortoise

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Re: Frontal Area / Cd numbers
« Reply #162 on: May 22, 2019, 08:17:15 PM »
The world record holding streamlined bicycle [Aerovelo - 89.59 mph] uses a video screen like you're thinking of. Another fast bike does the same, and also positions the rider facing backwards.
« Last Edit: May 22, 2019, 08:50:05 PM by tortoise »

Offline Sumner

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Re: Frontal Area / Cd numbers
« Reply #163 on: May 23, 2019, 12:05:00 AM »
I might be mistaken but I don't think the camera idea would ever fly with SCTA/BNI.  Now I realize you aren't going to set an international record at their meets but you might need all the time you can get on the salt to prep for an international record.  George has sure used those meets to his advantage.  I'd at least consider an alternative that would meet SCTA requirements even if it slowed the car at those meets,

Sumner

Offline jacksoni

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Re: Frontal Area / Cd numbers
« Reply #164 on: May 23, 2019, 05:52:29 AM »
Ah,  new and better technology (good cameras and video) causing trouble again. I am pretty sure SCTA had outlawed periscopes. A TV screen instead of a canopy to see out is likely not far behind. I agree with Sumner. The practice time etc could be invaluable. See all the issues all the fast cars have keeping things together before the big numbers happen (Target 550 and even George seem to wring stuff off pretty regularly)

What happens when the lights go out...….
« Last Edit: May 23, 2019, 08:40:10 AM by jacksoni »
Jack Iliff
 G/BGS-250.235 1987
 G/GC- 176.245  2018
 G/GMS-182.144 2019