Landracing Forum
Tech Information => Steering - Suspension - Rear End => Topic started by: maguromic on November 04, 2008, 09:48:02 PM
-
Just curious what some of the stream liners are running for suspension. Are they straight axle style with shocks or as some I have seen independent suspension? What are the advantageous running a independent system versus straight axle style with shocks on a liner? I thought I saw on Sumner's page some where the Speedway Motors liner and it had a indipendent front suspension.
I don't want to get into a debate over solid mounted versus suspension, so can we keep this thread on suspension?
-
Just curious what some of the stream liners are running for suspension. Are they straight axle style with shocks or as some I have seen independent suspension? What are the advantageous running a independent system versus straight axle style with shocks on a liner? I thought I saw on Sumner's page some where the Speedway Motors liner and it had a indipendent front suspension.
I don't want to get into a debate over solid mounted versus suspension, so can we keep this thread on suspension?
(http://purplesagetradingpost.com/sumner/bvilleother/Suspension-8.jpg)
Sum
-
Thanks Sum, thats the picture I was referring to.
Tony
-
It looks to me like they severely limit the suspension travel. The gold block at the front appears to have four adjustable suspension stops set rather close to zero travel. In any other form of racing a solid stop would be considered very upsetting for the suspension and would probably cause severe sudden handling issues.
Pete
-
Peter---I know you didn't ask for soild---but the suspension travel needed on a coarse that the faster cars are INTRESTED in running on is practacatically nothing---figure how far a car travels in a 10th of a second at 300+ and figure the reaction capability of even the electronic shocks--- :-P
-
Peter---I know you didn't ask for soild---but the suspension travel needed on a coarse that the faster cars are INTRESTED in running on is practacatically nothing---figure how far a car travels in a 10th of a second at 300+ and figure the reaction capability of even the electronic shocks--- :-P
Nice one Chapeau Bleu ( yeah that's you Sparky :wink: :wink:)absolutely...something in my mind keeps me coming back to this....despite little track experience, limited engineering know-how when it comes to shock absorber technology and no idea what soild means ,during the build of our car I argued a lot with people about the relevance of springs and shock absorbers to what we were doing and I'm thinking more like 200,let alone 300. I kept seeing a wheel failing to follow the ground because the spring rate and the dampening could not form a relationship that would track it at such high speeds....and as I've always said ...............
NO SCIENCE IS BETTER THAN BAD SCIENCE
-
You could be right that no type of active suspension could react to the active dynamics at 300 mph. But it isn't all about high frequency reaction. Look at the tracks from the Burkland liner. Low frequency dynamics, in this case bouncing, also come in to play. Any suspension beats nothing. Even if this surface was laser flat, long vehicles can still bounce through the reaction to throttle, brake, steering and parachute.
Shock absorbers absorb . . . shock. Damper is a better word. Take the shocks off of your car and drive around. A small bump sets off a reaction that goes on a long time. The shock on the streamliner helps damp out those reactions.
(http://www.landracing.com/forum/index.php?action=dlattach;topic=4720.0;attach=6665;image)
-
Dean, you are correct virtually everything has a natrual frequency---In walking the 1 mile to the 3 several times, I have seen more uneven tire marks on the salt apparently caused by torsional roatation of the chassis----some apparently caused by some pretty well know cars---front and rear not--- 411
-
I agree with Sparky that torsional oscillations can certainly occur in land speed cars. Most landspeed cars have frames that are very strong in bending, i.e. when acting like a bridge, but not much stiffness in torsion. The pics of the tire marks from the Burkland car would certainly seem to show some sort of torsional oscillation. The JCB streamliner did consider torsional stiffness if you look at the large CNC machine cover plate that covered the engine bays.
Rex
-
I've done some thinking on building a small streamliner and the approach I've considered was to use a beam axle at each end suspended by preloaded elastomer pucks. They could be rubber, urethane etc. This would give very limited travel and be somewat self damping if the right material is chosen. One puck above and one puck below would allow the very limited travel without the jarring stops. Just my thoughts.
Pete
-
I've done some thinking on building a small streamliner and the approach I've considered was to use a beam axle at each end suspended by preloaded elastomer pucks. They could be rubber, urethane etc. This would give very limited travel and be somewat self damping if the right material is chosen. One puck above and one puck below would allow the very limited travel without the jarring stops. Just my thoughts.
Pete
...that kind of describes our front end.....but there is some axle flex that is undampened which I'm not completely happy with.
-
man.... somehow we got on the suspend or not to suspend subject again
kent
-
man.... somehow we got on the suspend or not to suspend subject again
kent
Getting back to suspension, does any body know what the front hubs on the Speedway liner from or for what spindle they were fabricated for? Or was it front wheel drive?
-
I have seen alternating salt divots, on extremely good salt years as well as not so smooth, left by cars that have may have front supensenion that do not have the benefit of suspension and shock absorbing punematic tires profide. Something is causing the alternating pattern. Either the suspension cannot handle the extremely sharp high frequency inputs and it sets up an ocilation or the chassic is rotational flexing or BOTH. I have also seen the same alternating pattern left by rear tires leaving chirp marks under power as alternating spinning tires, that are aparently lifting completely off the ground. This is due to tire hop allowed by chassis ocilation or something in the suspension not preventing axel ocilation side to side.
-
John Mckichan designed and machined the hubs and wheels. The hubs use needle roller bearings with a thrust bearing for end play. With synthetic grease there is no sign of heat, even after a 300+ MPH pass.
As far as the control arm travel mentioned. The stops are set to "0" for transport. Don't remember how much travel for racing.
Ron Gibson, Omaha NE
-
Maybe way off subject, but Nitro Funny Car racer Tim Wilkerson tested in Florida this past weekend with front suspension with competitive times.
But it's only a 300 mph car.
-
lol---think he might like to try for 5 miles, on SALT :?
-
You could be right that no type of active suspension could react to the active dynamics at 300 mph. But it isn't all about high frequency reaction. Look at the tracks from the Burkland liner. Low frequency dynamics, in this case bouncing, also come in to play. Any suspension beats nothing. Even if this surface was laser flat, long vehicles can still bounce through the reaction to throttle, brake, steering and parachute.
Shock absorbers absorb . . . shock. Damper is a better word. Take the shocks off of your car and drive around. A small bump sets off a reaction that goes on a long time. The shock on the streamliner helps damp out those reactions.
(http://www.landracing.com/forum/index.php?action=dlattach;topic=4720.0;attach=6665;image)
These irregular tire marks came from this little episode:
(http://chevyasylum.com/bsf2008/shootout/burkland/part3/080924_0107r8.jpg)
Rear wheels off the ground.
(http://chevyasylum.com/bsf2008/shootout/burkland/part3/080924_0108r8.jpg)
Front wheels off.
(http://chevyasylum.com/bsf2008/shootout/burkland/part3/080924_0277r8.jpg)
Tracks show that there were times when there were NO tires on the ground.
(http://chevyasylum.com/bsf2008/shootout/burkland/part3/080924_0316r8.jpg)
Solid steel suspension.
(http://chevyasylum.com/bsf2008/shootout/burkland/part3/080924_0320r8.jpg)
Single disk brake.
Conclusions are left as an exercise for the reader.
RtR
-
Ray,
Those are absolutely awesome pictures!! The detail pics of the Burkland car are certainly of great interest also. When you say "single disc brake" does this mean that the large disc and double calipers is the only brake that the car has? as it certainly appears so. I have looked at the Burkland car several times but never had the opportunity to look at the details that you show in the pictures. There certainly does not appear to be any brakes on the rear drive gear system and I would suppose that if the front and rear are mechanically connected then only one brake assembly would be needed. And I guess that it is really only for stopping from 100 mph down. I suppose I could believe that there could be some drive train dynamics that may contribute to "hopping" that the car is doing but there are so many things that can be involved it would be just conjecture on my part. Tom and his dad are damn good engineers and their car is certainly a tribute to their efforts, I can only wish them more success in the future.
Again, a big thanks for the awesome pictures!!
Rex
-
They have one rear brake on the output shaft of the Liberty transmission. I looked at the liner at Speedweek becuase I am in the process of building a liner myself and wanted to get some ideas. I am not going to be using suspension but am pre-loading the chassis. We will see how it works.
-
Ray,
Those are absolutely awesome pictures!! The detail pics of the Burkland car are certainly of great interest also. When you say "single disc brake" does this mean that the large disc and double calipers is the only brake that the car has? as it certainly appears so. I have looked at the Burkland car several times but never had the opportunity to look at the details that you show in the pictures. There certainly does not appear to be any brakes on the rear drive gear system and I would suppose that if the front and rear are mechanically connected then only one brake assembly would be needed. And I guess that it is really only for stopping from 100 mph down. I suppose I could believe that there could be some drive train dynamics that may contribute to "hopping" that the car is doing but there are so many things that can be involved it would be just conjecture on my part. Tom and his dad are Dodge good engineers and their car is certainly a tribute to their efforts, I can only wish them more success in the future.
Again, a big thanks for the awesome pictures!!
Rex
I'm glad you enjoyed the photos. I was fortunate enough to be there for last year's Streamliner Shootout and follow the Burkland's and the other teams in their FIA/FIM record attempts and I agree with you about the engineering expertise that both Tom and Gene have shown. Their record for the flying mile is a testament to that as are all the other high speed passes they've made.
Luke's Daddy posted about the brake on the output shaft of the transmission. I didn't know about this, but it kinda makes me feel a little better for some reason. The other side of the front suspension has no brake rotor:
(http://chevyasylum.com/bsf2008/shootout/burkland/part3/080924_0313r8.jpg)
A quick note on this. I asked Tom about what appeared to be burned spots on the rotor on the left front of the liner. He told me that it wasn't nearly as bad as it looked and was more of an accretion of pad material on the rotor rather than hot spots that might have resulted in warping the rotor. I don't know enough about it to comment any further.
There are quite a few photos from the Shootout here:
http://chevyasylum.com/bsf2008/shootout/Welcome.html (http://chevyasylum.com/bsf2008/shootout/Welcome.html)
Re: your statement about brakes being good from under 100 mph: That's pretty much what Tom Burkland told me. To take this a little further, the reason this whole little "incident" happened is (in my opinion) because of the FIA rules stating that only one hour is allowed for a turnaround and that the hour begins when the lights are tripped at the end of the measured segment (Mile, Kilometer...whatever) and the lights beginning the return run must be tripped before 60 minutes elapse. Having said that, the Burklands decided to save some time in that hour by leaving the braking (chute, air brake panels and friction brakes) until "the last minute." That way they'd have more time to get the liner prepped for the return run.
There were a couple of things that I don't believe they expected to happen: First, I really think they expected BOTH chutes to open. That would have helped a lot, but as shown in my photo, only one opened up completely. I don't know if the 2nd one got fouled in the lines or what, but there was only one chute open as Tom approached the pit/turnaround area.
Second, I don't think they expected to have trouble shutting the motors down. As the liner was approaching the pit area, I could hear pretty dramatic downshifting, apparently in an effort to use compression braking to slow the liner. I suppose it helped, but it was still goin pretty fast as it entered the pit/starting/turnaround area. I've read estimates ranging from over 100 mph to around 75 MPH as entry speed. I don't know, because I was kinda riveted in place with my eye looking thru the lens of my camera. I DO know that I got somewhat splattered with salt that was being dug up as the liner went past my location (fairly closely...I spose I wasn't smart enough to move back a bit):
(http://chevyasylum.com/bsf2008/shootout/burkland/part3/080924_0111r8.jpg)
The liner finally came to a stop at what seemed to me to be just short of "running out of room""
(http://chevyasylum.com/bsf2008/shootout/burkland/part3/080924_0113r8.jpg)
In the photo above, he's almost stopped but you can see the semi in the background. That's on I-80. It seemed to me to be a little closer than I would have liked...I don't know about anyone else. And then there was that little issue with the motors continuing to run. Apparently killing the ignition didn't do the trick and the fuel pump shutoff failed. At least that's the story I got. It sat idling (dieseling on alcohol?) for 3 minutes according to the time stamps on my photos. Tom tried to cover the air intakes as did some other people by leaning across them and using their bodies to seal them off but it didn't work. Finally a CO2 fire bottle was found and shot into the main intake:
(http://chevyasylum.com/bsf2008/shootout/burkland/part3/080924_0189r8.jpg)
That killed the motors. As I understand it, there were some problems with the cylinder heads afterward. I don't know if the cold CO2 damaged them or not, but I was told that some repair work was necessary before making their next (and successful) record attempt. Needless to say, they didn't make the 1-hour turnaround deadline on that run.
I'll take a minute to get on a soapbox here. It's my opinion that the 1 hour turnaround limit was the underlying cause of three different incidents at that meet. Poteet/Main's fire that completely burned up the engine compartment of the Speed Demon stemmed from an EGT sensor that blew out of an exhaust header tube and burned through an oil line; The Mormon Missile's fire caused by propylene glycol coolant igniting (which was only part of a series of issues that resulted in a very serious fire) and the Burklands' close call with I-80 in an attempt to make the most of the time allotted. If the FIA's turnaround time was the same as the FIM's (2 hours) both the Speed Demon and the Missile could have been fired up and checked for problems before the return run was attempted. There wasn't enough time to do this in the 1 hour allotment. And I doubt that the late braking would have been attempted if an additional hour had been available to the Burkland team. Maybe, maybe not....hard to say, but I know that the short time frame was the reason for the attempts to minimize slow-down time.
It's my belief that the 1-hour time limit is unrealistic, dangerous and should be changed to bring it into "equality" with the FIM time period. I don't know how I can take it any further than stating my opinion here, but I really think that change should be made.
YMMV,
RtR
-
In the top photo it looks like a brake caliper and rotor inboard of the A arm.
DW
-
The picture you have labeled with no rotor, the one with the guy sticking his hand under the frame, has a brake caliper visible at the top, same as the other side.
-
Well, what a dummy! I've looked at that photo a dozen times and never saw it that way. Thanks for pointing it out.
RtR
-
Burkland car: As I heard it, the nut holding the fuel shutoff handle on the control cable came undone -- so when the handle was pulled the fuel did NOT shut off, ergo the continued running/dieseling.
And when I questioned one of his crew about the apparent "downshifting" I was told they use a (brnad name but I forget) transmission that doesn't downshift.
My comments..take 'em for what they cost you. Looking forward to this year's shootout -- with TWO photographers* plus me and the little digital. I see that Apple now has software to remove much of the shakiness from handheld video cameras, including phone cameras. That's gonna be a big help for lackeys like me.
* Got enough photographers now -- no more need apply. The event is going to be open to the public, though, I do believe. Come on out and see the show. It's somethig you'll remember forever.
-
Very cool pictures! :cheers:
I agree with the turnaround issue. Whatever the reason for a 1 hr rule, if it's causing injuries or deaths, it's a bad rule.
-
Very cool pictures! :cheers:
I agree with the turnaround issue. Whatever the reason for a 1 hr rule, if it's causing injuries or deaths, it's a bad rule.
Remember that the two wheelers have two hours, yes TWO hours to perform the required runs to get the FIM record..doesn't seem fair.
J
-
A few things....Ray,great pics. I`m guessing that car does not use any form of "free-wheeling" if it has a brake on the trans. shaft. Any one know how many degrees of steering it has? Those rod end/steering knuckles have to limit it to about nil. Jerry :-o
-
enough to go straight--when pointed straight-- not being a WA---I was told that was more or less the design parameters.
-
Burkland car: As I heard it, the nut holding the fuel shutoff handle on the control cable came undone -- so when the handle was pulled the fuel did NOT shut off, ergo the continued running/dieseling.
And when I questioned one of his crew about the apparent "downshifting" I was told they use a (brnad name but I forget) transmission that doesn't downshift.
<snip>
Thanks for the info on the fuel shutoff handle. That's something I didn't hear.
I read that the transmission was a Liberty. I don't know if the version in the 411 has the ability to downshift or not. It could have been variations in wheel speed as the wheels left and then returned to the salt. My ears interpreted it as someone double-clutching to downshift, but that's only conjecture, I spose.
I can't agree with ya enough about coming out to see the show. Wow! Talk about sensory overload. Even though there were periods of inaction while teams were preparing for a run or in a wind hold, there was still enough happening in the pit area that I could take that time and walk around, shoot photos, talk to people and never be bored in the least. And to see the smiles on the faces of Rocky and Ack and George and Ron when they held a record-setting time slip in their hands was fantastic. I'm havin a hard time waitin until SW. But maybe I otta get back to my website projects so I'll be ready for it when it gets here.
RtR
-
Just by the pictures I can only surmise that there is a brake I cannot see on the end of the transmission for the rear wheels (we do see a picture of the rear drive hubs with no brakes apperant) and a disc on each front wheels as shown with suspension/steering components. This would be 3 brakes....