|
Post by thisnametooktolong on Feb 19, 2011 3:56:25 GMT -7
Best track conversion table?
I recently purchased a 35 foot best track for my son with the champ timer. Besttrack was great. I received the track Via UPS so fast I thought they had Monica Lewinski personally escorting the packaging Via UPS ground. (Keeping the drivers happy and hammered down). This has made a huge help in tuning for the pack and District race. My question is; is there a conversion table or formula to convert the time of 35 foot track to the PDDR track? The car that I am running is turning 2.63s on the Bestrack 35 footer out of the box.
A little background. My son’s car is a huge compromise. The Pack track is some where between 50 and 2000 years old. The two outside lanes are so beat that they cannot be used. The two inside lanes are about as bumpy as a NYC street in the winter time, complete with pot holes. Building the car to be fast yet very stable was a huge concern. Therefore, no rail riding, and the center of mass is center of the stock wheel base. It is a three wheel car. The front end is tapered 1/16 more than the back, with the long BSA end as the front. ( gotta clear those center misaligned rails). The wheels are BSA stock size shape and width machined on a Taig micro lathe. The axels stock BSA shaped straightened and polished only. (No speed groves) angle of the back wheels about 1 deg. There is no visual drift to the car on a level surface in 10 feet. (Runs straight right along the tile floor).
Pack race #1, but they do not have a timer, just a simple win loose for two used lanes. It is a 30 foot track and the third place winner was more than 3 car lengths behind. The District race is a monster ply-metal (plywood with a metal top finish) track. Ivan set a track record on that monster 50’ race lane track of 3.9007, with a 4 run average of 3.904. ( start to finish is actually 50 feet the slowest cars finished 5.5+ and a Ebay ___ car at just over 4, an ABC car was even slower) My youngest son’s car that is a working wrist watch turned the track in 3.980 average. (3rd place) I attribute the second place finish to applying fresh graphite at check in. The winning time average was 3.902. You see I took a SWAG at the actual track conditions we where facing and thought that you don’t take a top fuel dragster to a street race. And you don’t take a mustang to a mud drag race. It seamed to work. Each of my boys far outperformed many, more advanced cars.
|
|
|
Post by thisnametooktolong on Feb 19, 2011 11:58:26 GMT -7
Scott Thank you;
But, I would like to say that I was not grandstanding in any way over any of the internet venders. That is why I went into so much detail about how different the tracks are. The pack race is on the equivalent of a 300 foot Mud drag. The pack race is a Pink slip race in a new industrial park. My FastTrack is a NHRA sanctioned track. We started building the cars in December. After completion, we raced last years looser car against the cars from this year on the best track. Last years car was at least 2 /10ths faster than this years.
Back to the drawing board: I had no idea how good or bad the track was going to be at district. But I did know that it was older, home built and plymetal. We had to survive the pack dirt road and the rules. I built an overlay out of mazonite and plastic porch railing. I then simulated bumps with a ball hammer. The lanes where curvy and misaligned. We then set out to build the fastest cars on each track. (a compromise of course)
In the end, I think that my youngest finishing first in den out of 36 kids by more than 40 inches aint that bad. I played it to safe over all. My oldest made it out of the den by maybe six inches. In any event I thought that having the kids survive nearly two months of tinkering with there fingers intact was outstanding. 2nd and 3rd overall aint that bad out of more than 150 competitors. My youngest went for pretty and my oldest (8) understands that frontal area can make a huge difference. His car is only ¼ in thick in the front and less in the back. I went through many lead pouring and cuttings to make it happen. (Wood is funny)
I know for a fact that the ___ car was not dropped. I was in the mall bathroom as my friend and child opened the shipping box @ districts. It was a matter of track, design, and luck, not bad engineering, or production tolerance. Lanes change, graphite is broken in and out, graphite choice, and the A/C hits that lane harder than the other lane.
Earlier you suggested that I send in my oldest son’s car for a proxy race. NOPE I know that it will loose like a 25 year old bench legged beagle chasing a rabbit. In the end I consider my son winning over ___ a triumph over the expensive car over the right car for the track. NOT a triumph over ___. He does not build swamp buggies, that is all there is to it!
PS, to re coupe the money that I have laid out, I was thinking of building tuned cars for different tracks on line. I don’t think any one does that ……. Yet!
BestTrack…. Rocks!
|
|
|
Post by Advance The Man on Feb 20, 2011 9:31:25 GMT -7
I've wondered how much graphite goes into oiled cars off the track. Most graphite scout folks throw so much of it on, that it must be inevitable. Ouch, that would be bad and so would the performance... The thought of graphite getting into the bores of one of my oil cars makes me throw up in my mouth a little bit... John could throw wheels on a stalk of celery and beat me, so those results didn't sound right... but now it makes sense. I can picture what a good oil prep with a little dose of graphite would look like..... paste.... Come on ThisNameTookToLong, come race with us! You have 3 weeks to put a car together and send it to ___'s March Madness Race.
|
|
|
Post by thisnametooktolong on Feb 20, 2011 17:26:00 GMT -7
You could see the swirls of graphite in the air surrounding the track at the district race just like a dirt track Roundy Round. This car my son and I made is for a road full of pot-holes and is finishing the 35 foot Best Track in 2.63 sec using graphite and no oil. I will have to make one to Win on a smooth as glass track and send it in for proxy racing. I am thinking my Best Track time would have to be in the 2.3s to not look like a fool. I can do that, it’s not rocket science.
|
|
|
Post by txchemist on Feb 21, 2011 8:33:51 GMT -7
Actually, it is rocket science. The current world record if run on a 35ft track would be a bit over 2.48. If your car had zero drag and zero friction, you could do 2.43 on a best track 35 ft.
|
|
|
Post by 2FAST4U on Feb 21, 2011 10:59:05 GMT -7
Actually, it is rocket science. The current world record if run on a 35ft track would be a bit over 2.48. If your car had zero drag and zero friction, you could do 2.43 on a best track 35 ft. I HAVE THE PDDR TRACK SET UP AT A 35 FOOT RIGHT NOW... the times for a pure stock car are at 2.45's - 2.46's i put ZO7 on the track to see what it would do WHICH IS A NEEDLE CAR WITH THE HOLESHOT XS2'S WITH TEFLON INSERTS ON OIL WHICH RAN A 2.835 FASTEST TIME ON THE 42 FOOT SET UP... ON THE 35 FOOT SET UP IT RAN 2.400 3 in a row... JUST MY
|
|
|
Post by thisnametooktolong on Feb 21, 2011 11:41:44 GMT -7
TX chemist Finally some one that knows, it has been so many years I forget the formula. But I think your number for a frictionless environment is wrong.
32/33 degree angle, From the start of the radius to the center of mass of the car is 81 inches. The radius is what 40 inches? And the entire length of the race from start pin to finish timer is 29’ 10 inches. For a total race of 358 inches. (That is what a 35 foot best track actually is. They are 35 foot but that includes wasted space at the top and the timer is not drilled at the end)
Doesn’t it go sine of the angle time’s 32 gives you the percent of G? So figure only ½ of the radius is close enough for a total ramp of 101?
I can’t even see the numbers on a calculator anymore. If you could get the theoretical number back to me I would appreciate it.
|
|
|
Post by txchemist on Feb 21, 2011 14:25:36 GMT -7
Glenn, That data helps quite a bit. Using both cars (pure stock and needle car) and making some best fit windage for the formulas, I can get close to actual now. Slightly off all around, but a good average for both types of cars. Your needle car can then be changed to assume the axle shrinks to zero, the wheel weight and inertia go to zero, and the air resistance goes to zero. Not much to improve because they never can go to zero, but if they did there here are the estimates. Attachments:
|
|
|
Post by Route 66 Racing on Feb 21, 2011 15:14:37 GMT -7
How do take the rate of deceleration into account when evaluating the differences in length?
|
|
|
Post by thisnametooktolong on Feb 21, 2011 15:51:32 GMT -7
Great post Txchemist,
But are your 35 foot estimates for a true 35 foot or a best track 29’10 inch track at a 33 degree angle?
|
|
|
Post by txchemist on Feb 21, 2011 16:43:24 GMT -7
Route 66- do two equations, one for the ramp with acceleration, and then continue with one for deceleration on the flat. Then add to get total time.
|
|
|
Post by txchemist on Feb 21, 2011 17:19:40 GMT -7
not using 33 degrees, 26.88 is typical best track in program, but I think PDDR is 27.1 degrees I can't find post except from FatBoy with that number, so that can make everything different, but 33 is too steep I believe.
|
|
|
Post by thisnametooktolong on Feb 21, 2011 19:04:21 GMT -7
You could possibly be correct about the angle; I have so many numbers banging around in my head at this time. I need to assemble the track again and check it. Another thing that should slow down my time is that there is a 1 inch change in level between the living room that was built in 1860 and the family room that was built in 1894. I have jacked and leveled each room, but the family room is about 1 inch higher. That change in level is taking place over the 3rd section of track partially in each room. I should just go to the hardware store and build a leveling kit for it. But for my testing purposes, I don’t think it is necessary. The idea is to build the fastest car that we can. We only use it for comparison of improvement or FUBAR engineering. Without the rubber feet on the carpets, I can actually assemble the darn thing in about 6 min flat. To hold the sections together, we use small spring loaded wood working clamps. The only reason we do that is because this old farm house shakes when the wash machine is out of balance.
|
|
|
Post by CDB Racing on Feb 21, 2011 19:20:54 GMT -7
I've wondered how much graphite goes into oiled cars off the track. Most graphite scout folks throw so much of it on, that it must be inevitable. YEP, Happen to an oil car I ran on our pack track. Others were running graphite and yes, it looked like a dirt track with the graphite flying off the car. I told the dad he had too much graphite on his car and he did not believe me until car started speeding up the more he ran it. I had to re-prep the wheels to get the graphite out. I hope it does not slow it down. My son's scout car - Graphite and not a very aerodynamic car ran one 2.58 on a 35' best track.
|
|
|
Post by Route 66 Racing on Feb 21, 2011 21:12:10 GMT -7
2DB,
That was kinda of my point, different tracks can't be accurately compared to the level being discussed. We've tracked every run we've made on more than ten tracks the past three years, identified the pertinent data relative to each of these tracks input this info into a really cool spreadsheet, ran the pivot tables only to learn two things. First the data is non-linear, even between similar track types, which means every track and car is slightly different. Second, I wish I had spent all of the time invested in spreadsheets into improving wheel, axle and alignment for the cars I was building. What the data will do is get me within .05 or so, and that is a little helpful say at Districts time when your changing tracks and trying to figure out if this year's set of wheels is at least in the ballpark. Other than that, looking forward to the new season, trying some new things, staying mid-pack (I wish), and I wish everyone a fast race year.
Route 66 Racing
|
|