A HANS device combined with a real tailfin would be a big leap in safety

[Franklin]

A real tailfin as in a BIG vertical stabilizer mounted BEHIND the gearbox. Even better would be a tailfin combined with a clamshell-type airbrake.

"...As tragic as it was, the recent accident at Walt Disney
World Speedway that left Indy Racing League driver Sam Schmidt paralyzed
from the neck down did not come as a complete surprise to Dr. Steve
Olvey.
Olvey, a critical care physician who serves as director of medical
affairs for Championship Auto Racing Teams (CART), said the open-wheel
racing community has been "lucky" that more drivers involved in the same
rear-impact collision as Schmidt have not suffered the same fate.
"We have known for a long time -- both in CART and the IRL as well
as Formula One -- from our studies with the crash recorders and the
types of accidents we've been having lately that rear-impact is the
biggest cause of cervical neck injury," Olvey said.
"We have had severe (spinal) fractures, but the sport has been
extremely fortunate that there hasn't been more paralysis. There were
two in Formula One (Clay Regazzoni and Didier Pironi) and those, to my
knowledge, are the only two in open-wheel racing since 1967."
Two, that is, until Schmidt's unfortunate accident Jan. 6 during
an open test session on the one-mile oval in Lake Buena Vista, Fla.
Although Schmidt's accident will no doubt bring the issue of auto
racing safety into the spotlight, Olvey said it is because of strides in
safety that Schmidt was able to survive such a violent crash.
"Most rear-impact (accidents) severe enough to cause cervical
fractures to the extent that they cause paralysis can also be fatal
because of a type of injury called the distraction injury," Olvey said.
A distraction injury, Olvey said, can occur upon violent
deceleration, such as in a crash. The force can cause the skull to
separate from the spinal cord because the driver's body is restrained in
the car and the head is propelled forward at the same speed the car was
traveling before it stopped.
"This has been the mechanism for a couple of the fatal crashes
over the last 15 years," Olvey said. "(Schmidt's crash) is the type of
crash that ... very likely may have been a fatal accident years ago but
because of safety changes in both CART and IRL cars, that has been
improved because of attention to the headrest, the padding in the seats,
the shape and design of the seats and the headrests.
"All these things have been improved in the cars so that the risk
of fatal injury has actually decreased -- although (CART) had two fatal
crashes last year."
The injuries that killed rising star Greg Moore and Gonzalo
Rodriguez in 1999 were not spinal-cord related.
While advances in safety have made open-wheel cars -- as well as
other forms of race cars -- more forgiving in crashes, technological
advances actually have changed the way open-wheel cars crash.
In the 1980s, Olvey said foot, ankle and leg fractures were the
most common injuries among open-wheel drivers involved in accidents
because the majority of crashes were frontal impact.
"What happened was that the cars, in the corners, were going at
slower speeds than they are now and they would do a complete 360-degree
revolution and then hit the wall frontwards," Olvey explained.
At that time, both CART and Formula One undertook measures to
strengthen the nose cones of the cars.
As speeds increased in the late '80s and early '90s, Olvey said,
he started noticing more hip and femur fractures because the cars began
going faster into the corners and spinning only about 270 degrees before
hitting the wall.
CART and F-1 responded by strengthening the sides of the cars,
adding energy-absorbing materials to the cars' side pods and drivers'
cockpits.
In the past five or six years, as speeds continued to increase,
the cars began spinning only 180 degrees before making contact with the
rear of the car, Olvey said. Hence the rash of rear-impact crashes.
In addition, because the cars are traveling faster, they scrub off
less speed before hitting the wall, resulting in a more violent impact.
"

[TimD]

In theory, the tailfin/airbrake is a good idea, but it would take careful research.

There would be a plane during the transitional state at which such a device would take on lift properties.

In one particular (Formula 1) case, in the days of those very, very high wings, Jackie Oliver had a Lotus wing suddenly collapse on him at maximum speed. When the aerofoil section bowed backwards, it suddenly produced massive lift, picking the tail of the car up, and putting it into an instant snap spin that he had no way of correcting, let alone anticipating.

But that's not to dismiss the idea. I think it may have mileage in it. Do you know of any r&d which is being undertaken on this? I can't imagine the problem is insurmountable.

[enzo]

HANS devices have already been ruled as required in F1, and drivers in CART & IRL have been evaluating them over the last couple of years. Expect to see them made mandatory soon.

A tailfin would be useless to a spinning car. Think for a second about it : a car travels thru a corner at a certain yaw angle, utilising every bit of aero downforce & in the case of a tailfin, every bit of lateral aero sideforce, that is available. Lose any of the factors that allow that speed, and a spin commences. Will the tailfin stop that spin ? NO - remember, the car is already using all the lateral force that the fin generates at any given angle. At best, it will only slow the rate of rotation slightly, but not enough to make any real difference in the results of the crash. To not upset the cars handling due to excess weight transfer, etc, the fin would have to be weightless, the mounts weightless, etc. A truely useless piece......

If you guys want a real laugh as to how little Frankie really knows about aerodynamics, look at his 'land speed car' on his web site ! TOO FUNNEY !!!!!

[jamie928]

Enzo.....whats the URL for Franklin's page?
BTW shouldn't Franklin be posting these at the Tech forum???

[enzo]

For some reason I couldn't find it again yesterday, even by selecting what I thought was the correct entry from the 'history' file. I'll try again today.

It was also posted in one of the 7g forum threads earlier, before he was banned from there.

[Franklin]

The propster is my land speed trials car that Enzo thought was "TOO
FUNNEY", even though he can't even spell FUNNY. ("If you guys want a
real laugh as to how little Frankie really knows about aerodynamics,
look at his 'land speed car' on his web site ! TOO
FUNNEY !!!!!")

The propster is also one of the few amateur-built sandwich composite
monocoque racecars in the whole wide world. A dragster-style car built
for land speed trials events, it was constucted by carving sheets of
polyurethane foam to fit in between the frame members of a conventional
steel-tubing spaceframe and then covering the foam with a fiberglass
cloth used in cigarette boats. This greatly enhanced the torsional
rigidity and energy absorbing characteristics of the frame while
eliminating the need for a mold.

I have learned from first hand (and sad) experience that sandwich
composite construction makes possible one thing that cannot be
accomplished with other fabrication methods -- a cockpit that is BOTH
lightweight and virtually indestructible. On July 9th, 1989 I observed
Craig Arfons attempt on the World Water Speed Record at Lake Jackson
Sebring, Florida. Craig drove a lightweight turbojet hydroplane with a
fiberglass and kevlar sandwich composite hull. The boat became airborne
at a speed variously estimated as 250 to 400 mph. I watched them recover
the entire front two-thirds of the hull as a single piece. If one of the
anchors for Craig's safety harness had not failed, Craig probably would
have survived.

VW Bug/Airplane/Propster Comparison

1965 VW Bug:
(Specifications)
Weight - 2,050 pounds (as tested)
Frontal area - 19.9 square feet
Engine - 1,192 cc, 40 horsepower
(Road Test Results)
Drag at 60 mph - 105 pounds
Top speed - 72 mph
Quarter mile - 22.9 seconds at 54.5 mph
Acceleration - 0-30 in 7.5 seconds
0-40 in 12.2
0-50 in 18.8
0-60 in 29.4
0-70 in 47.8
50-70 in 26.9

With 19.9 square feet of frontal area and drag of 105 pounds at 60 mph that works out to about a .6 drag coefficient. With a .6 drag coefficient, the 1965 Bug needed 30 horsepower at the rear wheels to go 72 mph. (The literature I've read on the open-cockpit open-wheel version of the 1937 Auto Union grand prix car gives a .6 drag coefficient for it, so apparently for a fully enclosed car the Bug has a fairly draggy shape.)

Sonerai II airplane (two-seater)
(Specifications)
Weight - 950 pounds max. gross
Engine - 1,700 cc VW, 65 horsepower
Propeller - 52-in diameter, 44-in fixed pitch
(Flight Test Results)
Minimum take-off roll - 900 feet at max. gross weight
Take-off speed - 65 mph
Top speed - 175 mph indicated airspeed at 4,000 rpm
Cruise speed - 130 mph at 3,200 rpm

So the Sonerai, even with 500 cc more engine displacement and over 1,000 pounds less weight, was still only going about 10 mph faster in the quarter-mile than the 1965 Bug even though ultimately the Sonerai was over 100 mph faster than the Bug.

The propster has an 1,800 cc engine and a frontal area of 10.4 square feet (about half that of the Bug). With me in it, it weighs about 1,000 pounds (pretty close to max. gross on the Sonerai). I'm not sure if its been reaching 50 mph in the quarter, but it's at least 40 mph.

Sunday (Oct. 3, 1999), I finally got in some good trial runs with the propster. The first two runs were around 40 mph while the third run was a little over 50 mph. Adjustments to the steering helped a bunch (backing front tire pressure down from 40 pounds to 25 pounds, cranking in about an eighth more toe-in, and changing how I gripped the butterfly). I could hit a dip in the road and steer through it without feeling like the car was going to get away from me. The brakes worked great. After about 7/10ths of a mile, the propster was hitting a little over 50 mph. I talked this over with the guy who built the prop (and who has also raced Formula Vee airplanes). He said that's pretty typical of this engine and prop combination. With a prop pitched for a 140 to 150 mph top speed, the prop keeps the engine at a relatively constant rpm until about 100 mph THEN the engine starts cranking up.

The propster uses an 1,800 cc VW engine. According to the literature I've read on propellers, about 50% of the acceleration of the air takes place at the propeller disk while the other 50% of the acceleration occurs BEHIND the propeller. So it would seem that with the air continuing to accelerate for a distance behind the propster, the potential is there for the prop to have a noticeable effect on drag reduction. (At 2,500 rpm the prop will pass behind each part of the car 40 times a second while at 3,000 rpm it will be 50 times a second.) Although there is no universally agreed upon theory for calculating rolling resistance, one formula I used says on pavement a 1,000 pound car will lose 2 horsepower to rolling resistance at 50 mph and 4 horsepower at 100 mph.

I've seen drag coefficients of .57 quoted for the Porsche 917/30 Can-Am car and .6 quoted for the late thirties Auto Union grand prix cars (rear engine open wheel open cockpit). I've also seen a drag coefficient range of .55 to .65 quoted for early seventies Formula One cars, and a drag coefficient of .6 for a current Indy car in superspeedway configuration. Although the drag coefficient could be less due to the effect of the propeller slipstream, using a drag coefficient of .65 for the propster results in a 46 horsepower loss to aerodynamic drag at 100 mph.


[This message has been edited by Franklin (edited 26 April 2000).]

[This message has been edited by Franklin (edited 26 April 2000).]

[This message has been edited by Franklin (edited 26 April 2000).]

[Crash Test]

What the hell was this? I am i in the Indy forum or have freelance terrorists taken over the ste from Craig and turned it into a plane forum or something?

[Franklin]

Enzo, Are we supposed to believe that the same physics and aerodynamics which keep airplanes (including fighters) going straight will stop working simply because a vehicle is on the ground instead of above it?

Vertical stabilizers have been used continuously at Bonneville for over 50 years on streamliners and lakesters.

Vertical stabilizers were on the first cars to set land speed records of over 300, 400, 500, 600, and 700 miles per hour.

[This message has been edited by Franklin (edited 26 April 2000).]

[Nuvolari]

At my age, I have a drag coefficient of about ten.