Author Topic: questions on seperation and opinions  (Read 4589 times)

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Offline Chris Horoho

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questions on seperation and opinions
« on: February 21, 2011, 07:41:43 PM »
well i have been working on a MC streamliner design with my father

I have heard many different degrees and such but curious to what you all think of this concept

I went with a form of 7 deg from top to bottom and unsure of sides but might be close to 6-7 (ill have to find out when i get more time)

but here are some screen shots to get some thoughts and opinions of the concept so far



the shape in the rear is for 2 chutes and below that is for the exhaust
"Pinky"

Offline Peter Jack

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Re: questions on seperation and opinions
« Reply #1 on: February 21, 2011, 08:18:29 PM »
I would be worried about the tail taking you for an unintended and maybe disastrous ride in the slightest cross wind with it extending so far back from the rear wheel. Nice drawings.

Pete

Offline Rex Schimmer

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Re: questions on seperation and opinions
« Reply #2 on: February 21, 2011, 08:39:50 PM »
Chris,
I would think that going with one of the standard NACA symmetrical wing profiles in revolution would be the way to go with your project. Lot of big government money spent on these shapes to make them low drag and to ensure that the air stays attached and if you look at the 66000 series they are designed to have "long runs of laminar flow" which is exactly what you want for low drag.

I actually think your tail is probably pretty close as one of the basic rules is to keep the aero center of pressure behind the mass center of gravity and I would say your concept does a pretty good job of that.  Keep us up to speed on your project looks neat. Any other details? engine(s) etc.

Rex
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Offline Chris Horoho

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Re: questions on seperation and opinions
« Reply #3 on: February 21, 2011, 08:47:59 PM »
Chris,
I would think that going with one of the standard NACA symmetrical wing profiles in revolution would be the way to go with your project. Lot of big government money spent on these shapes to make them low drag and to ensure that the air stays attached and if you look at the 66000 series they are designed to have "long runs of laminar flow" which is exactly what you want for low drag.

I actually think your tail is probably pretty close as one of the basic rules is to keep the aero center of pressure behind the mass center of gravity and I would say your concept does a pretty good job of that.  Keep us up to speed on your project looks neat. Any other details? engine(s) etc.

Rex
face down (not exactly more like standard but lowered MC riders position) with a 600-650 HP hayabusa engine
methanol is projected fuel and a w/a 70mm turbo setup
overall length is 24 or so feet
the front nose was corrected with a lower intake but lost file before saved so had to start from old file and didnt readjust it yet
24" front wheel with a 28" rear wheel
still working out the details but i went with this setup as it just felt right to me and my father in our ideas
 
"Pinky"

Offline Chris Horoho

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Re: questions on seperation and opinions
« Reply #4 on: February 21, 2011, 08:53:49 PM »
another of the ideas is capping off the 2 chute tubes with a 4 way cover that opens 4 ways but unsure how much it will help as seeing ack had issues with there chute cover ??
still in the air on it but will design it in at this time

thank you peter on the drawings comment
i am making sure we have every part of this designed before we lay one weld down
then will proto it out before making the real deal
we have a human body in cad that we have used to help in the design but lost it so need to reload it into the design

by the way is will have some smoothing done to it when its finished up and built
"Pinky"

Offline Rex Schimmer

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Re: questions on seperation and opinions
« Reply #5 on: February 21, 2011, 09:19:57 PM »
Chris,
Since you are doing everything in CAD maybe you can input your shape data into one if the new CFD sights and run some aero info. The site that I am thinking of is www.symscape.com. Your shape is so "pure" ,no big things sticking out from it, I would think that a CFD analysis would really be informative. You can read about the Symscape CFD info in the 2011 Jan issue of Racecar Engineering. I think you can get it on line.

Rex
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Offline Chris Horoho

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Re: questions on seperation and opinions
« Reply #6 on: February 21, 2011, 09:23:03 PM »
if i remember right my cad cam has CFD built in but my father is far more experienced with this specific cad cam then i am

but thank you for the link ill look into it
still tryin to learn what all the info will tell em in those programs
« Last Edit: February 21, 2011, 09:26:01 PM by Chris Horoho »
"Pinky"

Offline Jonny Hotnuts

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Re: questions on seperation and opinions
« Reply #7 on: February 22, 2011, 11:11:35 PM »
The wheel diameter looks very small in relation to the vehicle. A vehicle of this nature is built around available tires capable continuous high speed running. Your choices in OD of suitable tires are a minimum of 25". To be able to see over a tire of this size (*any any suspension-steering devices) with your given configuration would mean the overall vehicle height would be substantial in relation to other vehicles running in the same class resulting in a large wetted area and increased skin drag (*you will also have a good deal of skin friction on the large vertical tail surface area).
You may also have issues conforming to the roll cage requirements and also have problems with vehicle evacuation with the forward lay down position, but this is just speculation on my part and may not be an issue.


I would recommend deciding on a suitable front tire and buying a similar sized junk tire and building a mock up to confirm rider/body relationships. As good as 3d design programs are (even with bipeds) they can not always convey needed viewing angles for the rider/pilot and the ability to realistically fit in the model.

Good luck

~JH









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(when Im not working on the car, I am ususally playing classical guitar)

Offline Dr Goggles

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Re: questions on seperation and opinions
« Reply #8 on: February 22, 2011, 11:42:08 PM »
I would recommend deciding on a suitable front tire and buying a similar sized junk tire and building a mock up to confirm rider/body relationships. As good as 3d design programs are (even with bipeds) they can not always convey needed viewing angles for the rider/pilot and the ability to realistically fit in the model.
Good luck

Sage advice.

From where I sit I can offer this opinion.( notice I said sit and clearly stated opinion)

Suited up and strapped into a closed vehicle is a pretty poor approximation of comfortable. when it is hot, worse still humid, it goes from poor to abysmal. When you are forced to wait, it does happen, delay on the track or you just plain got ready too early it can affect your ability to act rationally, or even quickly. These are key ingredients when travelling on a slick surface at high speed with the very real chance you may need to operate safety gear.

Lying on your chest is not a comfortable way to wait. When I say lying , I mean strapped down in an insulated suit with a helmet on.

There are other issues. I don't have the proper terminology but it is more difficult to balance in this position as well , the easiest position is sitting up ....as your ears get closer to your centre of gravity it gets less easy to determine......

My final point is the march of time. I weighed 158lb's from the age of sixteen to forty, Jack Dolan suggested it might be smart to design the car for someone bigger, alas.

I shot from 158 to 188+ in less time than it takes to say "Upsize !" At nearly 46 I'm still just under 190 .....it makes everything a little harder to do and a little less comfortable in the confines of a cabin designed for someone a few sizes smaller..

When you're sitting on the line you want to be focused, clear headed and have all your faculties at your disposal.
Few understand what I'm trying to do but they vastly outnumber those who understand why...................

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THE LUCKIEST MAN IN SLOW BUSINESS.

Offline Chris Horoho

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Re: questions on seperation and opinions
« Reply #9 on: February 23, 2011, 09:10:41 AM »
i understand your opinions on the face down
but the head will still be the highest point as its similar to riding a top fuel motorcycle so to speak
and im looking at a 24" front wheel and a 28" rear wheel
the frontal area is approx 4.8 as its 2' wide and 3' tall
"Pinky"

Offline Chris Horoho

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Re: questions on seperation and opinions
« Reply #10 on: February 23, 2011, 07:25:01 PM »
with a 24" tire and 3" ground clearance loaded with rider in place that will give rider approx 15" of space above tire to view
i feel this is adequate space 
"Pinky"

Offline Peter Jack

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Re: questions on seperation and opinions
« Reply #11 on: February 23, 2011, 08:41:40 PM »
Chris, just remember you're going to need a full cage, a full harness to hold you in tightly and some way of keeping your arms and legs inside the structure in case of an accident. Then you're going to have to prove that you can exit the vehicle in a reasonable space of time, maybe 20 seconds, without outside help. The challenges should prove interesting!

Pete

Offline Chris Horoho

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Re: questions on seperation and opinions
« Reply #12 on: February 24, 2011, 04:30:32 PM »
Chris, just remember you're going to need a full cage, a full harness to hold you in tightly and some way of keeping your arms and legs inside the structure in case of an accident. Then you're going to have to prove that you can exit the vehicle in a reasonable space of time, maybe 20 seconds, without outside help. The challenges should prove interesting!

Pete
i dont feel i will have any issues with that but hey we will see
the canopy will be above the rider not in front of the rider
"Pinky"