Author Topic: Unsprung A arm front ends:  (Read 3663 times)

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Offline Rex Schimmer

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Unsprung A arm front ends:
« on: April 23, 2009, 08:41:31 PM »
Anyone know the reasoning for the un-sprung A arm front ends not being allowed?? Rule book section 3T.

My guess is some bad experiences but I would like to know.

Rex
Rex

Not much matters and the rest doesn't matter at all.

Offline RichFox

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Re: Unsprung A arm front ends:
« Reply #1 on: April 23, 2009, 08:43:28 PM »
So I have been told. Some dragster type chassis folded up I guess. That's pretty much how all these rules get in there.

Offline Glen

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Re: Unsprung A arm front ends:
« Reply #2 on: April 23, 2009, 08:58:41 PM »
The rule came into effect when the  old Kaplan-Karr lakester got sideways and the A-frame tore off the frame at the attach points and caused the car to crash. This was at El Mirage. SCTA/BNI also started to disallow older dragster chassis as they were thin wall CM steel tubing. They recommended mild steel and specified tube diameter and wall thickness shortly after that.
The car had been purchased and was being run by Mike Wesche who was unhurt.
Glen
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South West, Utah

Offline interested bystander

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Re: Unsprung A arm front ends:
« Reply #3 on: April 23, 2009, 10:09:37 PM »
IMHOP the call to ban tripods was a rush to judgement.

Saying that though, I'd be REAL concerned about a Lakester using available streamline tubing for that structure -The readily available  (w/o checking Aircraft Sruce etc.) as I recall, has a max wall thickness of .049.

In the case of Carr/Kaplan, I believe that was an older car that came from the dragstrip. Racing and TRAILERING takes its' toll.

It's probably unfair in some of the smaller classes, but better leave things alone and encougage beefy construction thruout.

A .250 wall by 1 5/8 or 1 3/4 axle with an aero fairing over it would keep my confidence up if I were a builder/driver and it'd  be pretty slippery.
« Last Edit: April 24, 2009, 12:14:26 AM by interested bystander »
5 mph in pit area (clothed)

Offline jdincau

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Re: Unsprung A arm front ends:
« Reply #4 on: April 23, 2009, 10:49:04 PM »
.035 and .049 wall
A quote from Aircraft Spruce's catalog

"The prices for streamline tubing have increased sharply. The only manufacturer of streamline tubing, Columbia Summerill, have encountered problems with cracking on the trailing edge intermittently for many years and it has been a worrisome problem for builders. In an effort to control the situation, Columbia Summerill have installed sophisticated inspection equipment in their plant to assure that no cracked tubing gets into the field again. The cost of the equipment is reflected in the prices
for the tubing which must be shared by all."
Unless it's crazy, ambitious and delusional, it's not worth our time!

Offline Freud

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Re: Unsprung A arm front ends:
« Reply #5 on: April 23, 2009, 11:06:43 PM »
Interested Bystander, the money you spent on your makeover was well worth it.

I assure u, there will be few people hanging out to drink your beer after dark.

Don't call your Mother. She won't recognize your voice.

Always concerned about you,

Shy Old FREUD
Since '63

Offline interested bystander

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Re: Unsprung A arm front ends:
« Reply #6 on: April 23, 2009, 11:24:20 PM »
Thanks, Freud for the compliments on my makeover. A few stiches, lipo and botox do wonders to keep up my 70-plus image.

After all the commotion over my old avatar, thot I'd come up with a more personal one!
5 mph in pit area (clothed)

Offline Freud

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Re: Unsprung A arm front ends:
« Reply #7 on: April 23, 2009, 11:29:13 PM »
Believe me, YOU DID.

FreuD
Since '63

Offline John Burk

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Re: Unsprung A arm front ends:
« Reply #8 on: April 24, 2009, 12:35:21 AM »
Dragster A-frame front ends look strong but the offset load stresses the tip it like the middle of an L shaped connecting rod .

Offline Rex Schimmer

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Re: Unsprung A arm front ends:
« Reply #9 on: April 24, 2009, 01:04:25 AM »
I am working on the front end design for my lakester and am thinking about using mostly aero tubing and very little suspension travel. Is it Lee Kennedy that I should contact for approval?

Rex
Rex

Not much matters and the rest doesn't matter at all.

Offline Glen

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Re: Unsprung A arm front ends:
« Reply #10 on: April 24, 2009, 10:24:25 AM »
Rex, it's Steve Davies

page 163 in the 09 rule book. Phone and e-mail for him.
Glen
Crew on Turbinator II

South West, Utah