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Author Topic: Spectre Streamliner  (Read 13466 times)
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dieselgeek
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« on: January 12, 2007, 04:13:50 PM »

Hello -

I figured it would be useful to get suggestions on our propsed streamliner buildup, so I got the OK to post up drawings of our project for Speedweek 07...   

A little background info:  We (Spectre Performance) brought our Ferrari F40 to the salt last year and became hooked on landracing.  Bonneville was great for product testing and marketing for us...  so we want to come back next year.  Recently, we had a chance to pick up a well-built streamliner (the 6969 car of Jr. Kurtz, usually driven by Kenny Hoover) the "Plastic Express."  We brought it home to our shop in Ontario, CA. (California)

After talking to the builder Roy Fjastad, he recommended we close the rear wheels or taper the rear end for better aero.  My main concern here is improved aerodynamics, as our powerplant isn't going to be as powerful as what they ran in the car previously.  We're not looking to set the world (or ourselves) on fire; we want to have fun and learn just like most of you.  A record would be nice, 200mph club entry would be even nicer...

I have a few design engineers on staff, and in their free time they came up with the below drawing for starters.  While we do not have the budget for full-on wind tunnel testing (maybe next year?), we *do* have the ability to print scale models if people think scaled testing is worthwhile?  I also have the ability to do some fluid modelling in FloWorks (coming online in the next week or two).


Anyways, here's a preliminary drawing.  I welcome any input I can get from you aero guys!

Thanks,
-Scott Clark




* concept drawing.jpg (127.33 KB, 1365x905 - viewed 679 times.)
« Last Edit: January 12, 2007, 04:16:04 PM by dieselgeek » Logged
Sumner
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« Reply #1 on: January 12, 2007, 05:32:52 PM »

Hi Scott.  I should be out working on the lakester or doing taxes or maybe figuring out how I'm going to Megasquirt my pickup, so I could be asking you lots of questions, but your new project hooked me smiley.  First I think you guys are going to really have fun with this one and knowing you I'll bet sooner or later you will have a record.

Ok here are my 'gut' feelings what could maybe help and you had better consult with an expert since I have only stayed at Holiday Inn once in my life wink

     

Hope you have or will have a long trailer, since you would need it for this.  I would extend the nose a slight amount and take out that dip by the front tire and extend the nose down into one teardrop shape.

At the back I reversed your angles and made the steeper angle in front of the back tires and then made the rear a more gentle slope to the back and don't chop it off if you can help it.  Seems like I have read you can have about a 2 1/2 to 1 slope back there and still keep the air attached.

I'll let someone else jump in now that knows what they are talking about.

c ya,

Sum
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PorkPie
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« Reply #2 on: January 13, 2007, 11:51:43 AM »

Scott,

it's not necessary to extend the rear end so as Sum shows - no effect on the aerodynamic, but you guys have to do, the rear end shape has to be turned around - what I mean, from there where you bump the body shape out to get space for the engine and wheels the big tapperd angle had to be - the rear the small angle, you got it exactly opposite around - the most areodynamic shape mistake are done by streamliner builder......so you be are not alone.

Also the nose, you can make it in a round circle like the whole front body is wide - not a circle going over into a angle shape, another curved area into the straight body shape. This increase the airpressure on the front.

See ya
« Last Edit: January 13, 2007, 01:16:25 PM by PorkPie » Logged

Pork Pie

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Sumner
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« Reply #3 on: January 13, 2007, 12:11:32 PM »

Scott, it's not necessary to extend the rear end so as Sum shows - no effect on teh aerodynamic,

The reason I extended the rear was to get the right slope on the rear like you mentioned and leaving the rear open leaves something on the table.  Mike is going away from the open back on the Ack Attack and I think he said that will be like gaining 50 hp or so over the drag from the flat rear.  Tom seems to think it is important also.

but you guys have to do, the rear end shape has to be turned around - what I mean, from there where you bump the body shape out to get space for the engine and wheels the big tapperd angle had to be - the rear the small angle, you got it exactly opposite around -

PorkPie that is what I did in my drawing.  I cut the back angle off and turned it around and cut and pasted it in front of the wheels.  Then took the front angle and put it on the back.  Since that angle is now less it makes the car longer if you run it out.

If you re-read my post again I think you will see we are saying the same thing, just in a different version of English  wink, except you think the squared off back isn't hurting the car and I think it will.  I also realize compromises have to be made.

I think in the front we are also basically saying the same thing.

c ya,

Sum
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« Reply #4 on: January 13, 2007, 12:22:06 PM »

Sum,
where you add the parachute?

the parachute open back is necessary - and if so, use them to Kamm - if you use the 6 degrees tappered you got not the problem.

the Ack Attack got his problem not on the rear end, he got it on a other spot.

I add the mod sketch that you can see what I meant


* streamliner mod.jpg (109.68 KB, 907x635 - viewed 615 times.)
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« Reply #5 on: January 13, 2007, 12:39:56 PM »

Sum,
where you add the parachute?

the parachute open back is necessary - and if so, use them to Kamm - if you use the 6 degrees tappered you got not the problem.

the Ack Attack got his problem not on the rear end, he got it on a other spot.

I add the mod sketch that you can see what I meant

Well while you were doing that I re-did the front from the top view and ended up with what you did.

   

I also think the air will detach at the front the way it is now and needs to either be more rounded in the side and "top" view or the transition into the body needs to be reworked.

The chute would be taken care of like what Tom, Seth, Maning, Wheeler or like what I'm planning on doing and on what Mike is going to do.  I still believe the squared off back is giving up something.  The rest we agree on.  I think what you did in front of and behind is exactly what I had done in my first drawing  smiley.

To bad these changes aren't as easy to do as it is for us to give advice wink.

c ya,

Sum
 
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« Reply #6 on: January 13, 2007, 01:14:19 PM »

The Tom Burkland/Sam Wheeler solution is fine but shows the problems.

Both are air brakes - Sam got a very small one and can be easy controlled to open exact parallel. Also he needs only a very small chute for his streamline bike.

Tom Burkland got a lot of weight in front (reduce the sideway force effect) of the air brake and also a exteme construction to get it open parallel. Tom's tappered* on the rear end is too much to Kamm, but he got enough power to take not care to this aerodynamic lack.

Using a air brake means

1. parallel open with the same size of brake pattern.
2. solid mechanic behind to hold the force constant
3. just behind the rear wheels (for four wheel vehicle) like Tom Burkland*

By the way, I hope my red lines can be seen on the mod sketch
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« Reply #7 on: January 13, 2007, 01:31:28 PM »

Scott
Welcome to the land of special construction.
I'm in agreement with your sketches and Pork Pie recommendations relative to changes to Roys old liner.
Liners tend to be so complex in many ways, having a small flat rear panel "Kamm effect" I don't think will hurt in a great way.  Particularly that the car is designed for "big" v8 power.  My  aero/design counsel is much more concerned about departure angle (7 degrees included angle) (or Pork Pie 6 degrees)).  I think that angle should be used aft of the wheels as well.  That means extending the rear a little, but that is one of the easier changes with a rather large return.  On my car when done that extension makes the flat rear panel only 6" wide.   I think that car enters the air rather nicely as it exists.  It should be a very nice ride and provide you with many enjoyable years of racing.


Rick
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« Reply #8 on: January 13, 2007, 01:40:07 PM »

This is great!!  exactly the kind of input I was seeking...


The skin on the car, as it sits now, is complete from the nose to the firewall behind the driver's cockput.  Fitment of our engine and turbos will require reworking the rear, so we decided it was a good opportunity to improve aero aft of the driver.

I'm getting our designer, Vincent, signed on and will let him elaborate or ask questions.   For now, keep it up!  We'll make revisions and post them up next week.


Sumner, anytime you're ready to 'squirt that pickup, you let me know!

-scott
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« Reply #9 on: January 13, 2007, 01:47:05 PM »

Scott

Are you going to do the rear skin in aluminum as was originally done by Mel Swain?
He did the skin and basic chassis of my car and the work is just outstanding.  As I evolve into a liner, I'm hoping to be able to afford his work, but it is doubtfull.  This kind of work "ain't cheap"
Panel fit is just so good.
 

Rick
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« Reply #10 on: January 13, 2007, 02:22:44 PM »

Scott

Are you going to do the rear skin in aluminum as was originally done by Mel Swain?
He did the skin and basic chassis of my car and the work is just outstanding.  As I evolve into a liner, I'm hoping to be able to afford his work, but it is doubtfull.  This kind of work "ain't cheap"
Panel fit is just so good.
 

Rick


The plan is to do the skin in exactly the same fashion as the original car in an effort to maintain what's an absolutely excellent body already.  The skin comes off and goes back on easily, everything lines up perfectly, one guy can have it all off or back on in 15 minutes...!

We hired Dean Westmoreland, an australian with much top fuel experience, and he has a resource to do the new tailsection in the same fashion.  I wasn't aware who skinned it the first time (thanks!) but it's quite evident they were expert at forming aluminum.



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« Reply #11 on: January 13, 2007, 03:16:40 PM »

I know Roy's streamliner very well.

When he was coming out with the car in 1996 I done a series of picture, was a very clean work with the frame coating...

The nose shape on the sketch is different to the real car...

To the 6 or 7 degrees - there is a discussion under the aerodynamic specialists for the last 60 years, why there is different - 7 degrees for aeorplane and 6 degrees for ground running verhicles.

To Kamm it had to be around 6 degrees for vehicles - it could be up to 6,2 degrees to Kamm.

I discussed this with the specialist in the Vaihingen University Wind Tunnel - the place where Kamm worked as a Professor for Aerodynamic.

Our opinion was that may be the bouncing airflow along the car makes the different. undecided

A plane, due to this that the air is complete around the plane body, creates a little bit different airflow.

A vehicle on the ground, like a streamliner, got the effect from the bouncing airflow along the streamliner body - this is also the reason for the different effects of flat or round bottom (depense on the distance from the body to the ground).

Rear end 6 inches wide - this is about 15 cm - this has to be enough for a parachute tube - so where is there a problem wink
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Pork Pie

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« Reply #12 on: January 13, 2007, 03:35:12 PM »

Oh it's not a problem Thomas.  To the contrary, it makes the rear very simple and practical.  I have considered light aircraft air brake devices, but dismiss due to complexity, and the fact that I do not plan on trying to go 400 MPH.....I think that will never be my ambition.
6 or 7 degrees included angle I think is probably just achedemic as we will see little difference in our application as you say because of ground effect.  Our concern will be to make boundry layer stay, or reattach because of the rather large wetted surface.
(long skinny car)
We are in agreement Pork Pie

Rick
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« Reply #13 on: January 13, 2007, 03:38:16 PM »

Rear end 6 inches wide - this is about 15 cm - this has to be enough for a parachute tube - so where is there a problem wink

Looks to be about 12-16 inches wide in your drawing and the first drawing.

Sum
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« Reply #14 on: January 13, 2007, 03:58:04 PM »

Sum
I think in Scott's drawing the rear skin is wider than 6 inches.
I was just suggesting that it change to be about the parachute tube dimension.  In my case that is two 6" tubes for the chutes.


Rick
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