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Post by Deleted on Jun 17, 2012 23:08:01 GMT -5
Some of the cars had special tasks to perform on public roads in Germany. The Auto Union and the Mercedes ran in prewar speed contests on a closed off section of the Autobahn. So these are GP cars that I will be showing you but not racing in their normal context. Every year for the past four years a online hobby store in Cincinnati lays out 200 feet of straight track to have an unofficial land speed record race. You have 165 feet to accelerate(scale mile) before the speed traps. Last year I entered a 1934 Auto Union type A streamliner that ran a respectable 38 mph with a FF-050 motor. The top speed was just over 52 mph with a twin NSR 46K King motored jet airplane bodied car. This year I will enter a Carrera Auto Union streamliner in the manufacturers class that has a braced chassis a NSR 40 K FC130 motor geared 16/23 sporting modified Penelope PiItlane wheels with the stock Carrera tires glued on. The stock class and the modified class require you to run commercially available 1/32nd scale parts in the cars. My modified car will be the Carrera Mercedes Streamliner with a 50 K NSR King motor with the braced chassis, ball bearings on each axle, gear 16/23 with the wheels tires borrowed from the Auto Union. The unlimited class is a run what you brung event with the only rules are you cannot use anything flammable like an Estes rocket propulsion or blow a five amp fuse between the controller and the track. The Mercedes will also be entered in that event with custom low drag machined aluminum wheels that are as tall as possible to fit under the body. The cars can use magnatraction to hold them on the rather bumpy track laid out on a warehouse floor. Any of you who know me realize that not only can I make good looking car I can make very fast cars that work. I spent a week rebuilding a lathe to make the wheels on and another week making some fine looking scrap. The machined wheels with the O ring tires have less than .002 runout in each direction. Not too shabby for a guy who just started using a lathe for something serious that has very strict tolerances. Both cars have no vibration in the drivelines up to about three quarters throttle free running which is close to what the tires will be turning loaded. Here are some shots of the cars and chassis's The Auto Union. The Mercedes. Wish me luck for next weekend. Ken
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Post by Deleted on Jun 17, 2012 23:27:48 GMT -5
For those that are wondering, the O ring drive tires on the Mercedes will have to be replaced each run due to wear and the stretching of the rubber from centrifugal force. There is .025 of the drive tire proud of the wheel. The front tires will have to be replaced every other run
The Mercedes final drive is 2.66 inches per motor revolution.
The Auto Union final drive is 2.32 inches per motor revolution.
My scientific wild ass guess is that the Mercedes will achieve 80% of rated motor RPM and the Auto Union will achieve 70% of rated motor RPM at the timing trap.
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Post by Mark Huber on Jun 18, 2012 10:03:31 GMT -5
Very impressive Ken. I wonder if we should create a special "spaceship" category for cars like this. These stream liners are awesome. So, for those of us who are somewhat mathematically challenged, just how fast do you expect these cars will go... in mph?
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Post by Deleted on Jun 18, 2012 11:41:12 GMT -5
Mark, I would never admit to being mathematically challenged if I were a banker. These numbers are based on best guess estimates of motor out put to load placed on it. I have no way of testing drag in the geartrain or wind drag at speed. This is a once a year event that there is no testing available for before the race.
So the Auto Union has a 40 k motor and I am guessing it will have reached 70% of rated RPM at the 165 foot mark.
40,000 x .7 = 28,000 RPM 28,000 RPM x 2.32 inches per revolution = 64,960 inches per minute. 64,960 inches per minute = 5413 feet per minute 5413 feet per minute = 61.51 MPH which is just short of my goal of 100 KPH
The Mercedes with it much bigger more powerful motor I am guessing will reach 80% of it's rated RPM at the 165 foot mark with the lower rolling resistance wheels.
50,000 x .8 =40,000 40,000 RPM x 2.66 inches per revolution= 106,400 inches per minute. 106,400 inches per minute = 8866 feet per minute 8866 feet per minute = 100.75 MPH
The Guinness record for a 1/32 slot car is something like 32 MPH. The local record is 52 mph for an unlimited class car.
I have loaded my two guns and I have three shots each for the event. I built them as best I can and we shall have to see how close my guesses were.
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Post by Mark Huber on Jun 18, 2012 12:53:01 GMT -5
From the Guinness web site: The fastest slot car was a Scalextric Honda F1 replica, which reached a speed of 983.88 scale mph (1,583.4 scale kph) when it was controlled by Dallas Campbell (UK) of The Gadget Show at the Chatsworth Rally Show, Chatsworth, UK, on 6 June 2008.
"Scale MPH" is the standard measurement for speed records on slot cars. Since the majority of cars are built to a 1/32 scale, their speed is measured over a distance that is 1/32 of a mile (165 feet). In standard speed terms, this car managed an impressive 30.94 MPH - meaning it would be breaking the speed limit in residential areas in the UK![/i] So, why aren't you guys inviting the folks from Guinness? Just think of the T shirts you could have made! Just wondering. www.guinnessworldrecords.com/set-record/
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Post by Deleted on Jun 18, 2012 13:10:45 GMT -5
Hi Mark this is a local group and the rules may not be consistent with the rules used for the record run. Our speed is the top speed recorded after traveling 165 feet and the record is for the average speed of the car as it traveled the scale mile 165 feet. I think the certification costs are prohibitive for a Guinness record for a small local group without major sponsorship and we would have to change the timing format to what they were running in the UK. It is just for bragging rights anyway. I keeps people from getting to serious about it. . . .
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Post by Chris Wright on Jun 18, 2012 13:15:46 GMT -5
And you're not serious about it?
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Post by Peter Seager-Thomas on Jun 18, 2012 13:19:15 GMT -5
An interesting project. I don't imagine Carrera expected this of their models!
Well done.
Peter.
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Post by Deleted on Jun 18, 2012 13:50:52 GMT -5
I do take every car I build seriously and build to win with out of the box thinking. I have read upon the prewar world speed record events that took place during the off season. The work done by the engineers and the mechanics were amazing with the technology they had at the time. The Mercedes still holds one of the top five speeds ever recorded on a public highway 75 years later. The Auto Union the Rosemeyer had his fatal accident in was a car that they had accidentally stumbled across ground effects with long before it was ever used again in a GP race car. Look at this photo of the Auto Union right before the crash, you can see the elements of ground effects in use. Peter, yes Carrera never expected to have their cars run at these speeds but for a hobbiest like my who enjoys the history of the cars what other body would you use for a speed record car. The wheelbase is long, the body is streamlined and there is room for tall thin tires under it. It is the perfect choice. Here is a photo of the machine work I did on the rear Penelope Pitlane wheels to mount the taller thinner Carrera tires. I have never made a part like that before and it turned out great on each try.
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Post by Mark Huber on Jun 18, 2012 14:05:36 GMT -5
I thought I'd add this to the thread. I love posters, and this one is stunning if somewhat poignant, given what happened.
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Post by nuvolari on Jun 19, 2012 2:49:38 GMT -5
...Every year for the past four years a online hobby store in Cincinnati lays out 200 feet of straight track to have an unofficial land speed record race... Hi Ken, The event sounds interesting, some photos are always welcome to see Keep us posted? Cheers, Danny
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Post by Deleted on Jun 19, 2012 7:49:25 GMT -5
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Post by Mark Huber on Jun 19, 2012 9:41:34 GMT -5
Ken,
The last few moments of that video make me wonder what might happen if your Mercedes reaches maximum velocity and takes flight. Is the body shell made out of Kevlar?
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Post by David Lawson on Jun 19, 2012 10:52:52 GMT -5
I thought I'd add this to the thread. I love posters, and this one is stunning if somewhat poignant, given what happened. There is a memorial to Bernd Rosemyer in a nice quiet garden area at Donington, my wife and I sat and thought about this great man when we last visited the museum. David
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Post by Deleted on Jun 19, 2012 10:53:18 GMT -5
Mark both cars have enough magnet that they will stick on the track upside down. The game is to balance the amount of magnetic attraction with the amount of drag added. The guys will remove magnets to gain speed till they come off the track. The warehouse floor is not very smooth and the Carrera track does have some bumps in it. The other reason the cars come off the track is that they have a tire come unglued that will cause them to shake horribly. I did my tire testing on 30 K Dremel tool. The O ring tires will expand but not come off the wheels due to the high shoulder around it. The O rings are .093 and the groove for them in the wheel is cut .060 deep. I also stretch a 2 or 3 size too small O ring over the wheel so it has a better chance of staying on.
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