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Author Topic: Scaled down LSR  (Read 10174 times)

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Offline bbarn

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Re: Scaled down LSR
« Reply #15 on: January 05, 2010, 02:45:36 PM »
Rob,

My model would be a bit shorter than yours, 1/12 scale should put it around 28-30 inches, I forget exactly what the length is and I didn't bring my laptop today:




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Offline Rex Schimmer

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Re: Scaled down LSR
« Reply #16 on: January 05, 2010, 04:09:45 PM »
Rob and bbarn,
Buy the book "The Leading Edge" and read it many times. I can't remember the authors name, but I will get it for you when I get to my hotel. He addresses so many things that are important to LSR racers. The book is about aerodynamics of sun powered race cars, which are pretty slow, but as long as you run sub sonic everything he discusses applies to LSR cars. I carry this book with me almost all of the time and when I have a "bright" aero idea for my lakester I look up the idea in this book. I know I have read it 10 times.


bbarn,
Really like your concept, non flat bottom and good aero shape in the plan view.

Rex
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Offline Rex Schimmer

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Re: Scaled down LSR
« Reply #17 on: January 05, 2010, 08:11:32 PM »
Rob and bbarn,
The book is: The Leading Edge by Goro Tamai published by Robert Bentley. Probably get it from Amazon.
 Best book on practical aero I have found.

Rex
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Offline bbarn

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Re: Scaled down LSR
« Reply #18 on: January 05, 2010, 08:15:09 PM »
Thanks Rex, there is still a bit to do yet before I can call it ready for testing. Rob and I need to get together and measure for the cockpit dimensions. Once I have the cockpit designed I can determine the best location for it, it will either be directly in front of the forward wheels or directly behind them. With that in place, I can finalize the positions for the rest of the internals, then the air intake and forward canard wings should complete the model.
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Offline bbarn

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Re: Scaled down LSR
« Reply #19 on: January 05, 2010, 08:16:32 PM »
Quote from: Rex Schimmer on January 05, 2010, 08:11:32 PM
Rob and bbarn,
The book is: The Leading Edge by Goro Tamai published by Robert Bentley. Probably get it from Amazon.
 Best book on practical aero I have found.

Rex


Thanks Rex, I'll look it up I looked it up. ISBN-13: 9780837608600 for others that are interested.
« Last Edit: January 05, 2010, 08:26:48 PM by bbarn »
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Offline Dr Goggles

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Re: Scaled down LSR
« Reply #20 on: January 05, 2010, 09:05:43 PM »
 ....as I've pointed out before , don't be operating machinery or a vehicle after you've been reading that book.....in fact the last time I had surgery I had a pre-med read of Tamai, they didn't just think I was asleep ,they thought I was in a permanent vegetative state and they started harvesting my organs........as you can guess they didn't give 'em all back.

In all seriousness , it is a very,very in depth book and there is still some debate about its applicability to what we do* , just like the bible, gospel to some ,a good story to others.

*encompassing aero efficiency, safety, practicality , cost, and dare I mention ,style....

OK, let the wild rumpus start.


BTW Barn ,gutsy effort.
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Offline bbarn

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Re: Scaled down LSR
« Reply #21 on: January 05, 2010, 09:17:17 PM »
No guts, no glory  :?
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Offline Peter Jack

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Re: Scaled down LSR
« Reply #22 on: January 05, 2010, 10:54:56 PM »
Bbarn, why not put the front wheels one behind the other? That would narrow up the frontal area.

Pete
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Offline bbarn

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Re: Scaled down LSR
« Reply #23 on: January 05, 2010, 11:14:17 PM »
with the tandem arrangement, we felt that if one tire went it could/would take the other with it. In this arrangement, we are going to separate the two tires with some thick shielding to prevent a cascading failure. It's not out of the question to run them tandem, but with the risk of one going out and taking the other as well as the complication of steering, this seems to be the way we are leaning right now.

I'm also looking at adding some camber to the fuselage to lower the nose a bit further. If I can get it down far enough, there will be minimal tire/fairing showing. Right now the frontal area is somewhere around 2.7 ft2, I still have to recheck those numbers since I have made some changes since those numbers were calculated.
« Last Edit: January 05, 2010, 11:17:20 PM by bbarn »
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Offline Peter Jack

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Re: Scaled down LSR
« Reply #24 on: January 05, 2010, 11:30:44 PM »
Good thinking. I've seen them offset just over the width of the wheels. That should prevent the cascading crisis. Just a suggestion.

Pete
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Offline robfrey

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Re: Scaled down LSR
« Reply #25 on: January 05, 2010, 11:40:29 PM »
Quote from: Dr Goggles on January 05, 2010, 09:05:43 PM
....as I've pointed out before , don't be operating machinery or a vehicle after you've been reading that book.....in fact the last time I had surgery I had a pre-med read of Tamai, they didn't just think I was asleep ,they thought I was in a permanent vegetative state and they started harvesting my organs........as you can guess they didn't give 'em all back.

In all seriousness , it is a very,very in depth book and there is still some debate about its applicability to what we do* , just like the bible, gospel to some ,a good story to others.

*encompassing aero efficiency, safety, practicality , cost, and dare I mention ,style....

OK, let the wild rumpus start.

Sounds like it's over my head. Does it talk about ground effect at all and it relationship to drag?

BTW Barn ,gutsy effort.
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Offline bbarn

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Re: Scaled down LSR
« Reply #26 on: January 05, 2010, 11:44:09 PM »
I'll order it tomorrow and we'll see.
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Offline bbarn

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Re: Scaled down LSR
« Reply #27 on: January 06, 2010, 04:45:39 PM »
Quote from: Peter Jack on January 05, 2010, 11:30:44 PM
Good thinking. I've seen them offset just over the width of the wheels. That should prevent the cascading crisis. Just a suggestion.

Pete

If I stagger the wheels, how am I reducing frontal area? All that will do is make the steering more complicated and give me the same forward profile.  :wink:
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Offline Peter Jack

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Re: Scaled down LSR
« Reply #28 on: January 06, 2010, 08:59:28 PM »
You're probably right. When I looked at the drawing originally the front view of the fairing looked rather stout but when I look at it now you may only gain a small amount. I really do like the overall shape.

Pete
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Offline willieworld

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Re: Scaled down LSR
« Reply #29 on: January 06, 2010, 09:53:58 PM »
better recheck that number    my  guess would be 6 sq ft                                                willie buchta
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