In the car world they use frontal area x Cd. In the aircraft world drag is measured in flat plate equipment. I think we are actually in the aircraft world and are flying aircraft at zero elevation but we do need to factor in ground effect.
Btw, these are Tom Bs words, not mine and I have to agree with him.
IE frontal area on the Carbiliner is deceptive. I can’t remember what the number is but it was pretty big. The fuselage is actually fairly small even at its thickest point but frontal area is based total shadow cast from front or back. The cross section of the car near the thickest part of the wing and wheel pants are a bit less than the thickest part of the fuselage. These two areas of the car are very different shapes but pass though the same section of air at different times.
It is not “Area Ruled” perfectly but it is not horrible either. We could have done better and I am trying to keep track of the changes for Mark II.
I like the idea of using nitrous as an intercooler. Just inject it right after the turbos. I would not spray it on an intercooler.
I would start off on Methanol as many guys don’t run any cooling system at all and get away with it when running meth. You just need to run it very rich and you will need a killer ignition system to light that wet mixture.
I have thought many times of getting rid of the heavy intercooler and running about 600 hp of nitrous right after the turbos (300 for each).
I would probably not use it until 4th and 5th gear.
Rob Freyvogel
#496
AA/BFS
All I know about aerodynamics is what I learn from reading and the experiences of others such as yourself Rob. Based on my reading the objective for my LSR project is to reduce frontal area to the least possible number using the best Cd geometry I can come up with. My wheel options are limited, and also limit the body geometry because I have to fit the elec. motors inside the wheel envelop, so thin cross section and profile aluminum wheels are all I see so far that will work. I started with M/T 16" profiles which fit the car shape but didn't leave room to plumb the motor coolant. The wheel profiles as currently drawn fit the car and give plenty of room for the elec. motors. Vertical stability is another challenge.
I remember back when I was a kid on the farm we'd shoot a quick burst of butane gas from the tractor tank to chill our soda bottles for lunch (propane didn't come along until later). Had to be really careful because the ice cold gas would freeze the Dr. Pepper and explode the glass bottles in a heartbeat. We need something similar to cool the intake charge between the turbos and the engine intake.
I spent the better part of yesterday researching the subject and I've come up with a plan to design just such a system using non-flammable refrigerant gas. No compressor, no condenser, no dryer, just high pressure liquid refrigerant, digital thermostatic expansion valve(s) and expansion tank(s) where the compressed air passes between the turbo and engine and an accumulator tank.
I'm looking to combine the methanol fuel tank with turbo-air routing in my currently design with finned refrigerant lines into an air-fuel-refrigerant intercooler to chill fuel, air, and extract heat through the refrigerant gas simultaneously. The methanol would chill first from direct liquid contact with the refrigerant lines, then extract heat from intake tubing before being burned in the engine. The refrigerant lines would also be in welded contact with the intake charge lines to suck heat through thermal conduction. The system would be programmed through the engine management controller to trigger refrigerant flow through the system based on thermal metering of the air intake and discharge ports at the intercooler tank.
Hot refrigerant gas would exit the intercooler and fill an accumulator tank during the run. Between runs the high pressure liquid refrigerant tank and the accumulator tanks would be recharged and/or drained ready for the next run. The system wouldn't be super light but it would definitely be lighter, more effective, and dependable than carrying several hundred pounds of iced water on every run. My design has limited room...I have to combine systems where possible to make everything fit.