Landracing Forum
Tech Information => Technical Discussion => Topic started by: hawkwind on March 19, 2007, 02:16:46 AM
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Im after pics and recources /plans etc of the small engine sized (G H I ) streamliners , what was successful ,what was not ,starting planning stage for a streamliner and as I only have the resources for one shot only Im keen to do it correctly
Cheers
Gary
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Y es I have looked at the links section and pics on this site , but I don't know there history or success as a certain red machine has trumped the lot
Gary
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Are you speaking of a car or a bike ?
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Jack I assumed G, H & I gave the game away , one of those 4 wheel thingies , why a car ,simple , by the time its complete I will be to old for motorcycles LOL
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The car streamliner is undergoing quite a revolution again.
The famous John Vesco car was the first of the narrow liners and was so revolutionary that is was only allowed to run for time only until the Wizards saw the writing on the wall.
The Don DiBring car suddenly went so fast that is was the subject of a lot of unsuccessful noise to make him do an unheard of backup run at El Mirage.
When he repeated the outstanding performance at Bonneville it left the former critics only talking to them selves.
The Costella liners have taken the next performance step.
My idea is to get a really small curl that is even more aero than a shaved head guy and get the "Good Old Boys" talking to themselves again.
The more money, plans, and science you apply the more the Hot Rodder wants to knock you off and they do.
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hey, lave us shaved head guys out of this.
I know nothing about aerodynamics.
look at my sig line!
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EYES ONLY !
SPEED SECRET TO FOLLOW :
Brian is a nice guy and all but it is more likely I would put him in a door slammer. :wink:
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Long and skinney seems to be the pattern.
Jack and Rick have certainly made a favorable impression.
Make certain that the nose isn't a wing.
FREUD
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Also try not to make the side profile a wing, you don't want to fly if you get sideways.
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Im after pics and recources /plans etc of the small engine sized (G H I ) streamliners , what was successful ,what was not ,starting planning stage for a streamliner and as I only have the resources for one shot only Im keen to do it correctly
Cheers
Gary
The Costella Streamliner #988 and the McBride & Moreau Streamliner #286 start both very successful in 1996 with a very similar, very small streamliner. From 1996 to 2001 the record was pushed from both teams from 178 mph to
248 mph (I/GS and I/FS) under SCTA/BNI - Jim True run FIA with the Costella to 253 mph, which is only 5 mph under the current Blown FIA record.
Meanwhile, Rick Yacoucci is using the Costella streamliner very successful with bigger engines up to 360 mph with 92 ci blown engine and 316 mph in I/BFS.
Both cars shows possible solutions for a very fast concept. The different between the Costella and the McBride & Moreau concept is, that the Costella concept works only without suspension and a flat, very close to the ground positioned, floor.
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One thing everyone forgot to say.....and we learned it in the late 70s and early 80s and even have a commemorative rule....
FRONT WHEEL STEERING!
and above all, build it like your life depends on it if you crash....
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Stainless, why would you try to confuse the issue with something as backward as front wheel steering.
It's a lot easier to parallel park if it has rear wheel guidance.
FREUD
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Stainless, Also remember the fastest car in the world is rear steering. :roll:
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Hawkwind
Think long and hard about how you're going to do the body . That part of the build takes an unbelievable amount of time .
John Burk
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Stainless, Also remember the fastest car in the world is rear steering. :roll:
The car you mention didn't do much steering with the rear wheels but they acted as a rudder as it flew along the ground.
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Jack, I guess that is why they had Andy, a RAF pilot, guide the car. :-D
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Two schools of thought here.
Costella & Yacoucci are the class of the field for G, H, and I. You couldn't go wrong just copying them.
On the other hand, I would guess you are building this for DLRA, not SCTA. All the records are wide open. Get your self a Briggs & Stratton lawn mower engine, save a bunch of money, and set a record. :-D
Ok, Ok.
(http://pages.sbcglobal.net/dean4/_images/DSCN1595a.JPG)
No, not a giant camera man, it's that small. Lay flat on the ground and lift your head up just far enough to see. That's the idea. LSR Plans? Never have been, never will be. Stretch it out long to avoid stacking anything to get it as low as possible. Aero is the subject of many very long books.
Motorcycle engines are the horsepower choice here. You didn't mention if you were going blown or unblown, gas or fuel. Ain't no such thing as too much horsepower. If it's gas you need a high compression engine. If it's fuel you need lots of nitromethane. And a big budget. If it's blown you need a bigger budget. You are super rich, right?
Spend a couple of days looking at these:
http://www.yacoucci.com/gallery/Neb (http://www.yacoucci.com/gallery/Neb)
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Jack, I guess that is why they had Andy, a RAF pilot, guide the car. :-D
You got it !
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Two schools of thought here.
Costella & Yacoucci are the class of the field for G, H, and I. You couldn't go wrong just copying them.
On the other hand, I would guess you are building this for DLRA, not SCTA. All the records are wide open. Get your self a Briggs & Stratton lawn mower engine, save a bunch of money, and set a record. :-D
Ok, Ok.
(http://pages.sbcglobal.net/dean4/_images/DSCN1595a.JPG)
No, not a giant camera man, it's that small. Lay flat on the ground and lift your head up just far enough to see. That's the idea. LSR Plans? Never have been, never will be. Stretch it out long to avoid stacking anything to get it as low as possible. Aero is the subject of many very long books.
Motorcycle engines are the horsepower choice here. You didn't mention if you were going blown or unblown, gas or fuel. Ain't no such thing as too much horsepower. If it's gas you need a high compression engine. If it's fuel you need lots of nitromethane. And a big budget. If it's blown you need a bigger budget. You are super rich, right?
Spend a couple of days looking at these:
http://www.yacoucci.com/gallery/Neb (http://www.yacoucci.com/gallery/Neb)
super rich ROFLMAO , I have several engines that are capable of some reasonable HP and lots of other motorcycle bits and pieces that can be used for a stream liner , I can also make or do most things myself (jack of all trades master of none ) ,though the steering is a new experience, yes I will basically copy copy copy anything that is a proven performer,but I do want to try out some of my own ideas as well , Thaks all for your comments
Gary
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That picture included the "Prosthetic Trailer" that delighted so many. :roll:
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Super rich? All of Jacks liners have been built with very limited budgets. It would be safe to say that some roadster engines cost more than what he spent on his liners. What makes him different from most, is his innovation, fabrication skills and his practical understanding of aerodynamics. As jack would say ?I like to cheat the air?
If you saw the new liner he is building, all this would seem very clear.
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Stainless, Also remember the fastest car in the world is rear steering. :roll:
The car you mention didn't do much steering with the rear wheels but they acted as a rudder as it flew along the ground.
Jack, if it was so easy :wink:they not need a driver like Andy Green.
Yes the car was pushed by two big jet engines, but the reality was, that Andy had a hard time to get the car straight, due to this that the two engines was parallel built into the frame....not the correct way, especially on ground.
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No, not a giant camera man, it's that small. Lay flat on the ground and lift your head up just far enough to see. That's the idea. [/quote]
This car looks very small, but if the racer I'm involved - the McBride & Moreau - than the Costella car is bigger than our streamliner...............no joke
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My racer...just tide
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Hi Gary, Just a thought, why not contact Costella and see if he wants to partner in a car in your "neck of the woods", This year he will have 4 streamliners, 1 lakester, and 1 Berkely, running all under his name and his partners. You would have a winning designed car and you could put your resources into engine development. Also," in the near future," there may be one of those streamliners available. You never know what future brings.. Just another resource you might want to check out.
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The guy that traveled Super Sonic on the ground in the 50s (rocket sled in New Mexico) wants to know how much of the total power of the SSC vehicle was used to just keep it on the ground for 90% of the distance measured as in the rules?
How much contribution did the the operator make and was it more flying than driving ?
One of them lives just 2 doors away so I can just yell the answer.
While he has slowed down a lot these days, I will want that much head start. :wink:
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The guy that traveled Super Sonic on the ground in the 50s (rocket sled in New Mexico) wants to know how much of the total power of the SSC vehicle was used to just keep it on the ground for 90% of the distance measured as in the rules?
How much contribution did the the operator make and was it more flying than driving ?
One of them lives just 2 doors away so I can just yell the answer.
While he has slowed down a lot these days, I will want that much head start. :wink:
Jack,
you mean Stapp who went a little bit over 600 mph....which was 20 percent under the sound barrier.....
To your question....they need no power to keep the Thrust SSC on the ground, more, the 10 ton weight cause the problem that the car stuck with the rear wheels in the powder fine sand when the car went through the sound barrier - the sound wave smashed the mud so fine under the car that it changed to sand, like fine sugar......
Ps. the sled went later super sonic - but only with monkey's on (up to 900 mph) - the fastest the sled went was close to 2000 mph. Today they go much faster......
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.............. Ain't no such thing as too much horsepower...........
Actually I think Rick has more HP than what he has run, but the transmission is becoming the weak link along with the links on the chain,
Sum
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The answer to a chain that is enclosed and getting too hot is.....
The Shock Wave that occurs when a vehicle goes Super Sonic is equal on all sides.
How much power was used to disturb that much earth at those speeds?
Big boom on bottom makes the vehicle fly up big time if it is contained.
A lot like a bullet tends to go the direction away from the containment.
An aircraft will get additional lift as it nears the ground and stuff. :wink:
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The answer to a chain that is enclosed and getting too hot is.....
The Shock Wave that occurs when a vehicle goes Super Sonic is equal on all sides.
How much power was used to disturb that much earth at those speeds?
Big boom on bottom makes the vehicle fly up big time if it is contained.
A lot like a bullet tends to go the direction away from the containment.
An aircraft will get additional lift as it nears the ground and stuff. :wink:
To push the Thrust SSC through the sand.......100 000 HP
Shattering the mud had a other reason......I know them.......but therefore you had to be at Black Rock during the attempt
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Did it take power away from the ability to just move forward ?
Tell me again how the surface was disturbed and not just the tracks that provided the limited directional stability.
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Supersonic pressure wave demonstration:
http://www.micom.net/oops/Some%20days%20you're%20good2.mpg (http://www.micom.net/oops/Some%20days%20you're%20good2.mpg)
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I seen dem boys from Hill and Nellis show us what fast really looks like during private time on the salt.
One a dem turk our piture when he went by wit da window on da bottom and sent it to me.
He was going a lot slower dat time.
The next day I got to meet him when he was running back from a 20 mile trip across the salt.
We found his gallon of drinking water at the 5 marker before we met him and thought we should leave it alone.
"Sometimes you eat the Bear and sometimes the Bear eats you."
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I believe "rear" steer worked great for the fastest vehicle in the world and some of the slowest...Hysters/Forklifts....It's the spot in the middle that's tough.
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Imagine how many feet you would run over at the swap meet if your wagon steered in the rear.
There , I said it and now Fritz is gonna do it.
The trouble just never ends. :wink:
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Did it take power away from the ability to just move forward ?
Tell me again how the surface was disturbed and not just the tracks that provided the limited directional stability.
The acceleration slows down to nearly zero..........................
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The answer to a chain that is enclosed and getting too hot is............
I'm going to follow the lead of Mike and the Ack guys. I think they have the answer......
Sum
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The answer to a chain that is enclosed and getting too hot is............
I'm going to follow the lead of Mike and the Ack guys. I think they have the answer......
Sum
There ya go!
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Jack, I remember when you told me that the LSR did not have to go in a straight line and you were going to tether your car and go around in a circle. To do the return run you planned to put the bridle on the other side and go around in the opposite direction
Have you found a big enough stake yet?
Does your centrafuge still squeak going CCW?
FREUD
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SPEED SECRET TO FOLLOW:
Half the fun of LSR is just telling Freud stuff.
Tether racing is a pretty big sport in LA .
I still have my Thimble Drome Prop Rod and the Roadster.
The cast roadster was built in 1948 and still in the box, having never been run.
My kid has a 4 stage D sized rocket powered car we built and it freights.
Lattin has a whole collection of those Nitro burners.
Arncha glad ya axed ? :wink:
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Let me see if I can stir things up a bit. I certainly don't have all the answers but Bryan Savage and I came out in 1988 with a small motorcycle engined streamliner with a stock Kawasaki Ninja 1000R engine with a turbo on it.
How soon you guys forget. My philosophy on the design was simple. Keep the frontal area minimal, punch a hole in the air once and then leave it alone. No swoopy wheel bumps or any of that high drag stuff.
We were the first 60 inch car in the two club and the first 60 inch car over 250 MPH and all on the event gasoline with a very mild powerplant.
Some famous person said " If you don't blow your own horn, someone will use it as a spitoon" Maybe it was Pliney the Elder or Ben Franklin.
I have been lurking and enjoy the messages. Good luck to you all and be safe.
Howard Nafzger
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Good to see you here Howard, Hope your back is doing better.
Oh and no..... some of us never forget. :wink:
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Yep Howard, it's like deja vue all over again. A lot of us remember when little motors were supposed to be slower than the big motors. That's probably why we broke that rule and went faster than they thought we could. Jim Burkdall and his dad's Bluebird with the 3/4 liter also really flew in the mid 80s.
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Howard, the best to you. I remember you and Bryan very well, real class, both of you. You have been the inspiration to alot of people. Hope to see you at the salt. I think you would enjoy the Salt Talks at the end of the road on Sunday, a good time with all the racers. Oh and thanks again for the clutch parts that helped us set our record, you will always be remembered.
John
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Let me see if I can stir things up a bit. I certainly don't have all the answers but Bryan Savage and I came out in 1988 with a small motorcycle engined streamliner with a stock Kawasaki Ninja 1000R engine with a turbo on it.
How soon you guys forget. My philosophy on the design was simple. Keep the frontal area minimal, punch a hole in the air once and then leave it alone. No swoopy wheel bumps or any of that high drag stuff.
We were the first 60 inch car in the two club and the first 60 inch car over 250 MPH and all on the event gasoline with a very mild powerplant.
Some famous person said " If you don't blow your own horn, someone will use it as a spitoon" Maybe it was Pliney the Elder or Ben Franklin.
I have been lurking and enjoy the messages. Good luck to you all and be safe.
Howard Nafzger
Hello Howard,
good to read a note from you. Yes, your streamliner was the first which was so "slimline". We done this concept at last to the extreme - the shape from the Kawasaki engine - plus 1/5 inch clearance - this is at last the outside cross section. And don't forget the shoe size on the front end of the car :wink:
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Don Di Bring would be surprised to hear all that. :wink:
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Don Di Bring would be surprised to hear all that. :wink:
Alright, Don Debring used 1981 90 ci to go 269 mph. He also packed a interested design concept together.
Meanwhile Rick Yacoucci run 360 mph (final speed) with 93 ci - call it evolution.....
You can say that Don kicked the idea on - but if you say so, the grand father of all this streamliner was than the Autolite from Mickey Thompson.
What Howard brought in 1988 was the consequence from all the idea's putting in his streamliner.
The Hoffmann & Markley streamliner was copy of the Autolite - but also this package was not so tide as it's now used from the Costella NT 2 or the McBride & Moreau streamliner.
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The first of the narrow liners goes back to John Vesco.
It is being restored now for his grandson to drive. :wink:
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The first of the narrow liners goes back to John Vesco.
It is being restored now for his grandson to drive. :wink:
Depends on what you call "narrow"........
Narrow is for me the questions, how much space is between the maximum necessary - most the engine or the driver - and the outside cross section - and by the Vesco liner was still enough space to get two piston more on both sides in.......
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Hey Speed Limit 1000, you have a picture of car 1976 from 1976?
I think Ben Jordan's 1976 was Don Debring's idea car, although he told Ben he had ideas to improve it, he built his larger to accommodate the motor, trans and 3rd member. Put the driver in the middle to add height for the motor. We borrowed that idea back from Don when we built the lakester.
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I was NOT the first one with a narrow liner. Not trying to make that claim. I don't spend much time on forums. Peace. Have your own heroes. I knew I could stir things up but I read all the chatter about motorcycle engined streamliners and not one mention of one of the most successful ones to date.
We raised a three year old record by 110 MPH so I thought it was worth pointing out.
I will go away now.
Howard
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Let me see if I can stir things up a bit. I certainly don't have all the answers but Bryan Savage and I came out in 1988 with a small motorcycle engined streamliner with a stock Kawasaki Ninja 1000R engine with a turbo on it.
How soon you guys forget. My philosophy on the design was simple. Keep the frontal area minimal, punch a hole in the air once and then leave it alone. No swoopy wheel bumps or any of that high drag stuff.
We were the first 60 inch car in the two club and the first 60 inch car over 250 MPH and all on the event gasoline with a very mild powerplant.
Some famous person said " If you don't blow your own horn, someone will use it as a spitoon" Maybe it was Pliney the Elder or Ben Franklin.
I have been lurking and enjoy the messages. Good luck to you all and be safe.
Howard Nafzger
Yep, you stirred the pot a little, and make everyone think but you noticed no one disputed your firsts... You went about the same speed as Don with 30 fewer inches. But don't go away, lurk, swoop and stir... :roll:
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On this my thing is narrower than yours, what Jack D claims re the Vesco liner is accurate- considering the TIME. With contemporaries plus or minus some years the likes of So Cal, the Shadoff Special, Hill- Davis, Herbert's "Beast", Goldie Gardner, Athol Graham, Mickey's 4 engine, the MG driven by Hill and Moss, etc., seeing Vesco's compared to those others you would have to say-at least I did, "That sure is a narrow little sucker!"
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I was NOT the first one with a narrow liner. Not trying to make that claim. I don't spend much time on forums. Peace. Have your own heroes. I knew I could stir things up but I read all the chatter about motorcycle engined streamliners and not one mention of one of the most successful ones to date.
We raised a three year old record by 110 MPH so I thought it was worth pointing out.
I will go away now.
Howard
If Seldom Seen Slim corrects spelling and punctuation, who corrects word choice?
Second to last sentence should read "We shattered" not "We raised" don't you think? :-D
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If Seldom Seen Slim corrects spelling and punctuation, who corrects word choice?
Second to last sentence should read "We shattered" not "We raised" don't you think? :-D
[/quote]
I think that would be Jack D.
:evil: :evil:
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Howard Im using the very same type of motor for my streamliner project ,though its not standard anymore :-)
Im looking at Jonny Allens M/C liner and it looks very narrow to me and that was way back 56?
Question I,ve read that a length / width ratio of 6:1 is optimal for good aerodynamics can any one confirm this
Gary
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You might want to size up a pursuit fish and see why they are faster than what they catch and eat.
Another proven design that is easy to copy for a car is a cruse missile.
Both have evolved into pretty efficient shapes.
You are going to be the big part so design and build the accommodations for you to survive first and that will dictate the starting point.
Allen's bike liner looks like a fish for a reason.
It is not so revolutionary as it is evolutionary.
"Being first is good, being the best is better." :wink:
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You might want to size up a pursuit fish and see why they are faster than what they catch and eat.
Another proven design that is easy to copy for a car is a cruse missile.
Both have evolved into pretty efficient shapes.
You are going to be the big part so design and build the accommodations for you to survive first and that will dictate the starting point.
Allen's bike liner looks like a fish for a reason.
It is not so revolutionary as it is evolutionary.
"Being first is good, being the best is better." :wink:
And every square inch that you don't have in frontal area... CD=0.0
Going faster is simple, see what the fastest guys did and then improve on it... :wink: I said it was simple, not easy :roll:
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OK, don't ask me how my post ended up inside Jacks quote unless it was divine intervention...WWJD
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Howard Im using the very same type of motor for my streamliner project ,though its not standard anymore :-)
Im looking at Jonny Allens M/C liner and it looks very narrow to me and that was way back 56?
Question I,ve read that a length / width ratio of 6:1 is optimal for good aerodynamics can any one confirm this
Gary
If you're using an airfoil, it is related to the Reynolds number, not really the length/width ratio. If you're not using an airfoil, better have some good software or time in a wind tunnel.
Reynolds number ~ velocity x length (where length in the airplane world is the chord length)
It is possible to make a relatively short vehicle low drag,there are several human powered vehicles that have done so. Unfortunately most of them have been very short wheel base and had very bad high speed handling as a result.
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Quote from: Howard on March 26, 2007, 10:13:53 PM
" . . . . . We were the first 60 inch car in the two club . . . . . ."
Question: What is a 60 inch car?? Does it refer to the approximate displacement of 1 litre? Or is there some other reference?
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Quote from: Howard on March 26, 2007, 10:13:53 PM
" . . . . . We were the first 60 inch car in the two club . . . . . ."
Question: What is a 60 inch car?? Does it refer to the approximate displacement of 1 litre? Or is there some other reference?
61 ci = 1 litre class = I/BFS in SCTA
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The Reynolds number is a little more that velocity X length also included is the the kinematic viscosity which is the dynamic viscosity of the fluid, air in our case, divided by the density of the fluid, again air in our case. So when you multiply the length by the velocity and divide by the kinematic viscosity, and if you get your units right, you end up with a dimensionless number that is the Reynolds number for that length. Now you can use any length dimension on your car and what you get then is the Reynolds number for that point, and obviously as you go farther to the rear of the car the length dimension increases of the Reynolds number increase porportionally. So far what we have is just a number that doesn't really mean anything without some extra information that typically is found out in a wind tunnel or testing. What we want to know is at the point that the length is picked and at the velocity that we have used, is the boundry layer laminar or turbulent? If, thorough testing, we can find the velocity at our selected length, at which the boundry layer becomes turbulent then we can calculate the Reynolds number for that point on the car and know for any Reynolds number above that we will have turbulent flow. So what has this really gotten us, not much unless we start comparing different car shapes then we can use the calculated Reynolds number to compare the efficiency of the shapes. Also if we happen a pile of money and can do wind tunnel testing with a scale model, obviously a 25% model will reguire either a higher velocity or more dense fluid (air) to be able to have the same Reynolds number at the selected point as a full size car. So when wind tunnel testing the Reynolds number is very important so that we can "scale" the information from the model in the wind tunnel to the real car.
As the speeds of landspeed racing vehicles is pretty fast I doubt that there is any place other that right at the very nose of the car that the boundry air flow is laminar, so we are typically working with turbulent flow and the real trick is to keep it attached.
Rex
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I was NOT the first one with a narrow liner. Not trying to make that claim. I don't spend much time on forums. Peace. Have your own heroes. I knew I could stir things up but I read all the chatter about motorcycle engined streamliners and not one mention of one of the most successful ones to date.
We raised a three year old record by 110 MPH so I thought it was worth pointing out.
I will go away now.
Howard
Howard,
may be my English was to bad.
What I liked to say was that you was (I say now may be) the first who used a so package - slimline streamliner with a very small displacement (60 ci) so successful - your 259 mph was a real good number nearly 20 years ago.
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Rex is pretty much right on with this, note I used a ~ not an = :) (typically ~ means proportional to)
One way to look at is to start with a vehicle length and intended speed, and find an airfoil that is low drag at that Reynolds number.
If you're designing a vehicle from a blank sheet of paper you need to start working out some basic dimensions.
I've briefly brought up this point before, but any wheeled vehicle will never retain a true airfoil shape, since there will be holes for wheels, air intake, parachutes and exhausts.
Anything in the rear is mostly irrelevant as the flow is probably non-laminar long before it reaches the back.
I think you're better off using a non-laminar flow airfoil than a laminar airfoil due to this, but I don't have a wind tunnel to prove this.
This is where I disagree with him, I don't think it's a matter of fast, it's a result of holes, projections and a not entirely smooth surface causing the flow to be non-laminar not the speed.
After all, there are lots of composite aircraft that maintain laminar flow at high speed, at least up until the wings are covered in bugs or it starts to rain.
Some of the recent motorcycle streamliners did an excellent job of dealing with these issues, trap doors for parachutes and doors to cover landing gear.
I've seen water tunnels before, and there are lots of issues with them to keep the flow laminar to even be able to test a scale model, but since water is denser than air makes a good medium to keep the Reynolds number correct for a scale model.
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The mysterious Reynolds number!
How I somewhat got a grasp of it is when I read that the bumblebee is swimming in MOLASSES when he flies- relative to us in the same environment.
"WETTED AREA" is another item one needs to keep as small as possible-if there is a flaw in Coslella's designs it may be too much of that. (Don't get me wrong, the guy's a wizard).
Rex's comment on laminar flow is right on (probly nil). In a conversation with Top Fuel aerodynamic wing guru Mike Mageira a couple weeks ago he made the same comment.
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Good Comment string, :-)
Howdy Howard - been a long time! :-) Ya still live in AZ? I am often in contact with Tom Monroe and he is in NC.
Roger the comments that Rex shared on laminar Vs turbulent flow. Laminar airflow is something that we might call it at times, but it is as elusive and believeable as the Easter Bunny, the Tooth Fairy, or Santa Claus. :-D
The attachment oh the attachment of airflow is the key to the kingdom. :wink:
Unfortunately too many folks interchange the words "laminar" and "attached" or substitute clean and attached for laminar. 8-)
Regards to All,
HB2
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:? Geeze Rex, Ouch!! tryin to understand that....man, my head hasn't hurt this much since 9th grade Algebra. :-o :-)
Pat
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g`day Howard, could you or somebody please post a photo of your streamliner 8-), as we down under can have a look at it,,
thankyou in advance, stay`tee....
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:? Correct me if I?m wrong. But, doesn?t ground effects come into play in the design? Round bottom verses flat bottom? If you have a narrow round bottom (streamliner) you wouldn?t have the air compression factor (otherwise known as air drag). The liner that is wider and has a flat bottom would seem to be at a disadvantage from the unwanted ground effects. Also, would it not matter that you could conceivably design a 2 ft tall x 3 ft wide w/frontal area of 6 ft2 and a 3 ft tall x 2 ft wide with the same frontal area. All other things being equal, the second design would be faster than the first design. Right?
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Terry
Honest answer - I really don't know. Concerning ground effects - I haven't seen any design that can do away with those pesky wheels and tires. No matter how wide/narrow or low/high you make it there seems to always be wheels and tires sticking out the bottom. My guess is a flat bottom (think Neb Therom II and III) gives a better chance of covering the tires. Or . . maybe not . .
I have run across some interesting streamliner aero info about a little liner build in Sweden a few years back. Google it at Dreamliner III. Somewhere in their web site they have an engineering paper concerning stuff I can't even pronounce let alone understand . . .
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:? Correct me if I?m wrong. But, doesn?t ground effects come into play in the design? Round bottom verses flat bottom? If you have a narrow round bottom (streamliner) you wouldn?t have the air compression factor (otherwise known as air drag). The liner that is wider and has a flat bottom would seem to be at a disadvantage from the unwanted ground effects. Also, would it not matter that you could conceivably design a 2 ft tall x 3 ft wide w/frontal area of 6 ft2 and a 3 ft tall x 2 ft wide with the same frontal area. All other things being equal, the second design would be faster than the first design. Right?
Absolutely beautiful sidecar by the way! I'm working on drawings for a streamliner and want to run a sidecar first before having to deal with landing gear, yours makes me not want to put a wheel on a stick!
In theory what you propose would be a better design to avoid the effects of the ground. If you look at the evolution of HPV (human powered vehicles) they started out as attempts to get as low to the ground as possible, and then started realizing the headaches with this approach and evolved to a higher body and streamlined wheel pants. When I get home I'll show links to make this clearer. All other things equal is often difficult to do in reality, especially if it's for a practical vehicle and not a wind tunnel model.
What you proposed would be a good university project, so if you have a mechanical engineering university with a wind tunnel, may be worth pitching it to them. I would not be suprised if this has been covered in a masters thesis somewhere, so maybe if I get a bit of time will try to sort it out with solid data.
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Terry,
Most of the present day publications on aero that I have give information relating the ground clearance of a streamlined vehicle and it is a ratio of the height above the ground to the length of the vehicle. What you will find is that the Cd, based upon the frontal area of the car, actually increases as the ground clearance decreases once you get below a minimum height. If you look at these numbers you think that Costello'd Neb Therom cars are obviously in violation of this minumum ground clearance height, but damn they are fast!!
I have my own idea why Jacks cars can violate this "rule" and be so fast and one day I will get a chance to see if it is right. Got to get my street roadster done first!!!!
As far as your question regarding two cars with the same frontal area and Cd but one is wide and the other is high it would depend on ground clearance as to which one is the most affected by ground affects. Get the book "The Leading Edge" by Goro Tamai, a little deep in some place and it is about solar powered cars but it is very applicable to land racing cars.
Rex
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If you look at these numbers you think that Costello'd Neb Therom cars are obviously in violation of this minumum ground clearance height, but damn they are fast!!
I have my own idea why Jacks cars can violate this "rule" and be so fast and one day I will get a chance to see if it is right. [/quote]
There is no trick behind and the reason is known - this car is simple not effect from the bouncing (airflow) wave.
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...........What you will find is that the Cd, based upon the frontal area of the car, actually increases as the ground clearance decreases once you get below a minimum height. If you look at these numbers you think that Costello'd Neb Therom cars are obviously in violation of this minumum ground clearance height, but damn they are fast!!..................
Small frontal area, no air under the car, low Cd, and good HP works good as long as the course is good. Rough course equals a parked car.
c ya,
Sum
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I realize that nobody knows me here, so I expect some disagreement with the following:
First, below the velocity at which we encounter compressability (~500 mph at Bonneville) the following factors, in order, are the source of drag of LSR vehicles that I have seen:
1. Separation
2. Wetted area
3. Laminar flow percentage
Separation is easy to spot once someone has made the conceptual leap that it exists. Look at any vehicle from the back and throw water at it. If it hits anything but a highly swept surface, there is separation. There are other sources, namely abrupt pressure recovery areas. We have to have wheels, but the treatment of the rear face of the tires is the largest source of curable separation. Second is the aft bumper - chute area. The rule: aft facing blunt areas are the largest drag contributor. This is well understood in aerospace, but only the best LSR vehicles have covered their parachutes with proper fairings. Stagnation (another form of separated flow) occurs on all of those forward facing abrupt transitions, like canopies. Make the canopy part of the aerodynamic shape of the vehicle, not an add-on.
Wetted area is next. Size matters, smaller is better. This begs the question that the original poster had of fineness ratio (length over cross section). The lowest drag form with no protuberences (wheels) has a fineness ratio of about 2.5 (a football). A 2.5 body has drag of less than 20% of a vehicle with a fineness ratio of 9 (typical LSR) with identical volume. Some of that comes from more laminar percentage, most of it from a reduction in wetted area. As a consequence, a low fineness ratio vehicle with more frontal area and less wetted area will have less drag than a high fineness ratio vehicle with more wetted area. The low fineness ratio will also allow more volume for less drag. Frontal area has no, repeat no, direct relation to drag.
Read that twice.
The relation of "frontal area" to drag died in aerospace science about 46 years ago with the Navy's towed mine detector experiments.
Finally, laminar run can reduce drag by significant amounts. It requires a positive pressure gradient to the transition point and TOTAL smoothness. Canopy joints, wheels, pesky access panels (no matter how well sealed) trip the boundary layer to turbulent. For LSR, it's far easier to fix the separation and the fineness ratio.
Bottom line, minimizing separation, minimum wetted area, and a fineness ratio of 4 to 5 should yield the lowest drag. If a tail is needed for stability, put it on a boom like a proper tail and leave the body fineness ratio blunt. Supersonic has a completely different set of rules.
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Frontal area has no, repeat no, direct relation to drag.
I believe you meant to say no direct relation to coefficient of drag.
If not, you're wrong unless they rewrote all the physics books. :)
Believe it or not, it is often easier to make a large vehicle with low cD than a small vehicle.
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Frontal area has no, repeat no, direct relation to drag.
I believe you meant to say no direct relation to coefficient of drag.
I don't think so. The point being made is that to enclose a given volume of stuff, the lowest drag form is not the longest and narrowest, but a fatter one with less surface area. The problem with this, of course, is that the short wheelbase is liable not to be very stable-handling. The Nebulous Theorem cars finesse this problem cleverly by being essentially two fatter bodies, one at each end of the car, connected by a real skinny, low surface area tube. This principle could be carried quite a bit further.
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Frontal area has no, repeat no, direct relation to drag.
I believe you meant to say no direct relation to coefficient of drag.
I don't think so. The point being made is that to enclose a given volume of stuff, the lowest drag form is not the longest and narrowest, but a fatter one with less surface area. The problem with this, of course, is that the short wheelbase is liable not to be very stable-handling. The Nebulous Theorem cars finesse this problem cleverly by being essentially two fatter bodies, one at each end of the car, connected by a real skinny, low surface area tube. This principle could be carried quite a bit further.
Maybe I'm too dense to get what he's saying, but every physics book and aerodynamics book clearly states the power to overcome drag is proportional to (frontal area)*(coefficient of drag)*(velocity cubed). If this weren't true, there would be no sense in cramming your body in an awkward narrow confined space.
The evolution has been from short and fat to long and skinny, and until I see the trend reverse highly doubt the claims. A pair of rather famous Indians seems to prove my point :) Note I'm not saying that you have to have a long vehicle to have a low cD or low drag, but it sure is difficult to have low overall drag with large frontal area.
One nice thing about long vehicles as opposed to short and stubby is that it's easier to separate the engine from the driver compartment with a good firewall, as opposed to trying to share the same space.
The human powered vehicle (HPV) Mango is a really good example minimal surface area, but they had to rework the front steering to make it have even ok handling from what I understand. At least it had minimal cross section area to get blown around in the wind.
Scroll down to the Mango bike, at 6 foot tall I'm amazed a person can squeeze in this, much less turn their legs to pedal :)
http://www.recumbents.com/WISIL/whpsc2002/resultstuesday.htm
http://www.recumbents.com/WISIL/whpsc2002/photos_tues/whpsc2002-demo-mango.jpg
Good sense of the size here:
http://www.recumbents.com/WISIL/whpsc2002/photos_tues/whpsc2002-demo-mango2.jpg
The yellow HPV in back is the Barracuda, an older but very successful HPV, the blue HPV in front is a camera bike, no canopy to see thru (camera is in the white tail fin).
http://www.recumbents.com/WISIL/whpsc2002/photos_tues/whpsc2002-demo1.jpg
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Maybe I'm too dense to get what he's saying, but every physics book and aerodynamics book clearly states the power to overcome drag is proportional to (frontal area)*(coefficient of drag)*(velocity cubed). If this weren't true, there would be no sense in cramming your body in an awkward narrow confined space.
But sometimes you can decrease cD by 11% by increasing frontal area by 10%. Thanks for the HPV link.
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Blue Foam,
Everything you have said is correct for the condition of complete laminar flow over the entire streamline body. If you have this condition the main contributor to drag is the friction between the streamline bodies skin and the fluid and also the pressure drag generated by the fact the the boundary layer is thickening as you go toward the rear of the streamlined body and as the streamlines combine at the end of the body there is a region of low pressure that is the thickness of the combined boundary layers. So in this case, complete laminar flow, shortening the length of the body will reduce the total drag by reducing the surface area, "wetted area" of the body and by reducing the depth of the boundary layer at the rear of the body thus reducing the generated pressure drag and a decrease in the frontal area will have almost no affect as long as the streamline shape has complete laminar flow front to rear. For bodies in high density fluids, i.e. water laminar flow can be maintained at relatively high speeds because the fluid density is high which make the Reynolds number fairly low.
BUT!!! ALL OF THIS DOES NOT APPLY TO LANDSPEED RACING CARS!!!
BECAUSE: LANDSPEED RACING CARS DO NOT HAVE LAMINAR FLOW!!! All of them are operating at Reynolds numbers that are in the multiple millions! At the speeds that they are running actual laminar flow probably only exist on the very front few inches of the body! The rest is turbulent flow! and if we are good at body design it will be attached, and with turbulent flow the amount of drag generated by skin friction on the "wetted area" is actually reduced and the major contributor to drag is the ability of the body to maintain attachment of this turbulent flow. Any place that it becomes unattached pressure drag will be generated.
Rex
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" Theoretical projects produce theoretical results."
NEXT ?
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Rex
I've been reading what you guys have been saying long enough that I think even I'm beginning to understand it.
John N
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I don't. Probably good we got a Street Roadster.
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It's also worth taking a long hard look at the underbody design of the JCB car and reading what they found during their CFD research. You can and should do all you can to reduce profile and skin friction drag but it all needs to considered in conjunction with rolling drag. JCB found that 60% of their aero drag was skin, 40% profile drag. With a design that was essentially zeroed in terms of downforce (to make sure it didn't fly but also didn't absorb power overcoming downforce) attention turned to rolling drag. What they found was that rolling resistance was in fact higher than their overall aero drag! So you can have the cleanest body shape in the world and still not perform as you might expect. Part of that rolling resistance is the friction of tyres on salt (which you need for drive and control) but a significant part of it turned out to be something that Ron calls 'spray drag' - designers of record breaking boats know all about this. Essentially it's the mixture of salt, dust and disturbed air under the car that increases drag and also affects the ability of the tyres to get a good clean grip with minimal drag from the surface. The air flowing under the car accounted for about half the total aero drag as well as trying to control the spray drag. The carefully sculpted underside and slightly raised nose were all designed to minimise this affect. As Ron says, the photographers are interested in the top view but the real technical challenge is on the underside! After the successful runs he was the one poking around underneath, delighted to find that it was as clean as a whistle.
Robin
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JCB found that 60% of their aero drag was skin, 40% profile drag.
. . . with turbulent flow the amount of drag generated by skin friction on the "wetted area" is actually reduced and the major contributor to drag is the ability of the body to maintain attachment of this turbulent flow.
Am I misreading Rex or does Robin's statement contradict his?
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Lets start with Carl's truck.
Why was it so fast ? :wink:
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Lets start with Carl's truck.
Why was it so fast ? :wink:
Power, weight, round on the front and clean rear end (last version)
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Lets start with Carl's truck.
Why was it so fast ? :wink:
Power, weight, round on the front and clean rear end (last version)
YUP!
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What Robin said regarding the 60/40 split of the total drag on the JCB car is a statement of the aero efficiency of the JCB car, i.e. the body shape maintains attached flow over most of its length therefore the only drag is the friction drag of the turbulent air going over the skin of the car and it has very little pressure drag (that is the drag caused by the creations of unattached turbulent air, vorticies, behind the car which are at high velocity and therefore low pressure) So yes on a very "aero" car skin friction can be the major component of the total vehicle drag. Viscous friction between the skin and the air is reduced by attached turbulent air flow BUT it is not eliminated.
To go fast at B'ville is done by either having a car like Stan's roadster and applying lots of good old American horse power or by trying to "cheat" the wind and build a more streamlined car. Of course the really fast guys, do both and are the guys hold the records.
Rex
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Lets start with Carl's truck.
Why was it so fast ? :wink:
Power, weight, round on the front and clean rear end (last version)
And here I thought it was the black smoke coming out the back, or was that just a smoke screen 8-) :roll: :wink:,
Sum