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PUGZCAT
recumbent enthusiast

Canada
281 Posts

Posted - 04/28/2012 :  09:28:15  Show Profile  Reply with Quote
Jgarb do you still have the Cheetah? If so recruit another 6'3" mega powerful rider, do a seat mold of his butt, cut the old seat out, install the new seat, update the tires, show up at Battle Mountain to race.
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Adam C
recumbent enthusiast

USA
227 Posts

Posted - 05/02/2012 :  14:00:38  Show Profile  Visit Adam C's Homepage  Reply with Quote
quote:
Originally posted by Jgarb

Adam. I came across your postings and information on the cheetah and I appreciate your interest. There were several things which you guys were speculating on that I thought would try to answer.

For the flying 200m record the course is a critical determinant in the top speed which may be achieved. It sounds like the site at battle mountain is extremely well suited to getting a hpv to top speed. We chose the road at Alamosa because of altitude and slope. Our top speed was partially limited by a restriction that we placed on ourselves . To a certain degree we were outsiders to the ihpva and we were concerned that individuals within the organization would try to find fault or suggest that we had cheated in some way in breaking Gardener's revered record. We decided that we would limit our total course length to the requirements of the Dupont prize. This is a really big deal since Chris had to pedal all out for the entire distance. On a much longer road a rider has the opportunity to pedal, recover without significantly dropping speed and the accelerate again. I am positive that Chris could have gone significantly faster on a longer course. The team had discussed going to the road at one point but in the end we were to spread out and doing thing with our families to be able to coordinate an effective effort.

Note that subsequent to our record there were , as we expected, accusations of cheating by other teams. Some even implied that we had gotten an aerodynamic push (not sure about the aerodynamic theory on that one). I believe that a year after our record Goldrush, varna, and Matt weaver all went to the site we used. I'm not sure that any of them exceeded 60 mph.

I do not want to discredit the work that was done by Gardener on gold rush. He set a great historical standard and was an inspiration to our effort. The Varna Diablo is an example of fantastic engineering, the product of years of work and learned experience.

Let me know if you have other questions about the cheetah. I'll try my best to answer but after 20 years my recollection of physical numbers will be sketchy at best

Jon Garbarino

Btw I don't have the log right in front of me but I believe we exceeded 65.48mph at least 3 times during our attempts. It may be in the report filed by the IHPVA witnesses in attendance (IHPVA archives maybe?)



Greetings Jon,

Great to hear from you. Thank you for the insights on the Cheetah. I have a few questions for you.

1) I quoted an article with this quote:

"Under Selig's influence, we decided to optimize the fairing aerodynamics rather than minimize its frontal area..."

Can you expand on this. Doesn't minimizing frontal area optimize fairing aerodynamics? What were the cheetah team's thoughts on this?

2) Do you think the semi-recumbent riding position can produce 80 mph (with a powerful rider of course)?

3) Given a longer run up how much faster could Chris Huber have gone in your opinion?

4) Do you think taking the Cheetah fairing and scaling it down to fit a much smaller rider could potentially produce a fast HPV?

5) What are your impressions, if any, of the Rob English's Mango HPV?

6) Where is the Cheetah today? Is it ridable?

Edited by - Adam C on 05/02/2012 15:23:49
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BlackMariah
Starting Member

USA
13 Posts

Posted - 08/01/2012 :  10:20:40  Show Profile  Reply with Quote
Off the top of my head here are some questions and thoughts that this discussion of the Cheetah brings to mind. The Alamosa Course had some problems, I am told. The road surface was probably not as smooth as Battle Mountain's where an annual automobile race had given Nevada's Department of Transportation incentive to do their best before we ever got there.

The altitude at Alamosa was pushing it for human respiration especially if the rider wasn't a resident of Colorado or in training there. Was Chris Huber acclimated? I know that Gardner flushed the Gold Rush with oxygen prior to Freddy's runs at a similar altitude. Battle Mountain is a good compromise altitude for many 'engines'.

The short wheelbase of the Mango was part of its undoing. The Kingsbury design was more oriented towards circuit racing and had more lock-to lock travel. It was lightweight for the many accelerations of that sort of venue. I was there when it went airborne, and though Rob is a very good rider, he was not able to hold as rock solid a straight line as Sam must do with his larger wheel between his legs limiting the steering. The advantage of that situation is also that Sam's very small changes in drive vectors produce a shorter overall line through the traps. The higher weight of the Varna helps to smooth its trajectory, and perhaps the head bubble, despite its supposed aerodynamic deficiencies, may also help pointing accuracy with it's slight extra drag providing the characteristics of the fletching on arrows. Again, a compromise requiring smaller frontal area than the ideal wind tunnel tested shape might suggest for that power level.

I have studied the video of the Cheetah and it seems to me it was more susceptible to side winds, though that could also be responses to road irregularity and the struggle for control at the highest output level of the rider. It also could be the aerodynamic theory at odds with the practicality. While Gardner's early Gold Rush versions followed a laminar flow theory meant to carry the laminar flow as far to the back as possible, he quickly 'hot rodded' the design to make it work better for the rider. It still depended on a fairly high expansion ratio rather than the dirigible ideal to maintain what laminar characteristics remained. It ended up being a less than perfect compromise that led to Gardner buying one of Matt weaver's larger volume machines, and then Freddy finding out just how refined the Varna's had become for riders of his size or smaller. We are still in search of the perfect machine for the size of rider that standard bicycling has made most common at the highest levels of competition.

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Jeff Wills
human power supergeek

USA
1214 Posts

Posted - 08/01/2012 :  18:56:34  Show Profile  Visit Jeff Wills's Homepage  Reply with Quote
quote:
Originally posted by Adam C

6) Where is the Cheetah today? Is it ridable?



Adam, I trust you've found the answer to this question.


__________________
Jeff Wills
All my bikes:
http://home.comcast.net/~jeff_wills/Gallery/index.html

Edited by - Jeff Wills on 08/01/2012 18:57:10
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