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sried, Thanks for the link, it does have a good spreadsheet to learn from but the code is buried in an xll and dll file. The dll has two functions ddydx Returns the second derivative of the interpolated curve at the given X using the defaults of Interpolate dydx Returns the first...

sried, Yes, now I get it, the conic won't work I need to use a cubic spline instead. Now I will focus on figuring out how to do that. I ordered a book on splines, I hope I can figure it out from that. Jonathan T. Schmidt http://www.schmidtmotorworks.com

How about if I use a general conic equation from five points? x y 0.0 0.1 0.25 0.2 0.5 0.3 0.75 0.7 1.0 0.9 (32 * x^2)+(-120* x*y)+(100*y^2)+(12*x)+(1) = 0 Can someone show me how to write an equation to get the: velocity in y axis acceleration in y axis jerk (change in...

Norm, thanks for the spreadsheet. I guess it is time to elevate my excel knowledge. Jonathan T. Schmidt http://www.schmidtmotorworks.com

Cronic, thanks for the spreadsheet, what do you think about the use of more than three points? Jonathan T. Schmidt http://www.schmidtmotorworks.com

sried "You could connect the position points using a Cubic Spline Interpolation. This has the advantage that third order equations exist continously which can be differentiated to give smoothed values for velocity, acceleration and jerk." I think you are on to something, the more I look at...

That is exactly what I was looking for, thanks. Also thanks for posting "h= increment" I was trying to figure out what the characters represented. Any other tips would be appriciated. Jonathan T. Schmidt http://www.schmidtmotorworks.com

I am trying to write some functions to calculate the velocity, acceleration, and jerk (change in acceleration) of some valve motion data. The data is typically about 220 points The x axis is evenly spaced with an increment of 1 The y axis is provided in a list of "position data" I would like...

sreid, I'm not familiar with end fences. Do you mean a plate parralel to the ground fit to the top and bottom of the side surfaces? In drag racing they use something called "spill plates" on the ends of the wings, is the design something like that? I am suprised about the suggestion "chopped...

I have entered a gravity powered car race like soap box derby for adults. The size of the car is a maximum of 4 x 4 x 9 feet. I would like to know what the lowest drag airfoil shape is that I can try to apply wherever possible. The average speed will be about 40mph with max at about 60mph. I...

"And lastly, the 8 exhaust rockets can add as much as 2,000 pounds of downforce at take off." Are you saying that there is significant down force from the exhaust gases? I doubt that it would be anywhere near 2,000 lbs. Jonathan T. Schmidt http://www.schmidtmotorworks.com

The concept is simple: 1. Raising the float causes the fuel to come through the booster with less throttle. 2. Reducing the air bleed size causes the fuel to come through the booster with less throttle. Jonathan T. Schmidt http://www.schmidtmotorworks.com

I am considering building a gravity racer and I wonder if ot is better to have suspesion or not? How would I determine the optimum weight? Any suggestions for steering geometry parameters? Caster, Camber, trail, scub radius etc. Jonathan T. Schmidt http://www.schmidtmotorworks.com

NX4 has it Jonathan T. Schmidt http://www.schmidtmotorworks.com

There is a company developing a system just like you describe with diesel injectors. They presented at AETC a few years ago. I don't remeber the name of the company but I think they were in Colorado. Jonathan T. Schmidt http://www.schmidtmotorworks.com

Yes, I am also looking into S7, I have heard of D2 but i have never seen it or machined it that I know of. I will check it out tonight. Jonathan T. Schmidt http://www.schmidtmotorworks.com

"FEA can be quite economical these days." Yes, I used FEA to remove weight anywhere that I could. Jonathan T. Schmidt http://www.schmidtmotorworks.com

Jason, I think it would be easier to have an expression that controls the configuration ie configuration=1 Then have conditional expressions for the mating distance based on the value of "configuration". You may also have component suppression expressions that are conditional based on the...

"It seems that EPD's design is lighter than the aluminium ones and is a highly optimized design, are they that expensive that manufacturing your own is of any benefit?" I intend to compete with EPD with a similar but slightly improved design. Jonathan T. Schmidt http://www.schmidtmotorworks.com

"I still dont see how you are going to reduce weight with higher strenght material though. Care to enlighten me anyone?" Because the cross section required to accomplish the same strength is less when higher strength material is used. This seems rather obvious to me, is there something more to...