Random Thoughts - Part Deux [NO POLITICS]

[NoHaveMSG]

Originally Posted by Spuds

Why specifically airspeed? I would think you would want to see static pressure on various surfaces more than anything else.

I would like to do pressure in the future but airspeed is the easiest to calibrate. Suction cup to front of car, note speed, note A/D reading. I figure it is a start with my limited ability.

[Spuds]

Originally Posted by NoHaveMSG

I would like to do pressure in the future but airspeed is the easiest to calibrate. Suction cup to front of car, note speed, note A/D reading. I figure it is a start with my limited ability.

If you are saying that you calibrate it in front of the car, then put it under the car, it is still going to be inaccurate. Calibration only accounts for that specific location of the pitot tube. It will still show precise data you can compare against multiple runs, but it won't be accurate to actual airspeed.

[NoHaveMSG]

Originally Posted by Spuds

If you are saying that you calibrate it in front of the car, then put it under the car, it is still going to be inaccurate. Calibration only accounts for that specific location of the pitot tube. It will still show precise data you can compare against multiple runs, but it won't be accurate to actual airspeed.

Yeah your right, difference in static pressure will skew it quite a bit. Maybe I just need to go back and rethink just using pressure transducers and forget airspeed.

[Spuds]

Originally Posted by NoHaveMSG

Yeah your right, difference in static pressure will skew it quite a bit. Maybe I just need to go back and rethink just using pressure transducers and forget airspeed.

Airspeed exiting the back of the car (assuming some sort of diffuser?) would be interesting data. Other than that, I would recommend pressure transducers on surfaces or strain gauges on whatever mounts for a diffuser/splitter if you have them. The biggest problem you are going to have is turbulence under the car. Idk the scale of that vs how take will affect the baseline, but be prepared for smoothing difficulties. That is one benefit of the strain gauge technique, it basically averages and damps for you.

[p1l0t]

Airspeed indicator measures the difference between ram air and static airpressure. The difference in the calibrations based on location might tell you something...

Sent from my SM-G975U using Tapatalk

[Spuds]

Originally Posted by p1l0t

Airspeed indicator measures the difference between dynamic pressure and static pressure. The difference in the calibrations based on location might tell you something...

Sent from my SM-G975U using Tapatalk

FIFY. (Yes I know I am an ass)

Edit, this is wrong...

[NoHaveMSG]

Originally Posted by p1l0t

Airspeed indicator measures the difference between ram air and static airpressure. The difference in the calibrations based on location might tell you something...

Sent from my SM-G975U using Tapatalk

That was my initial plan, I knew the data wouldn't be clean but to the point that Spuds brought up, it may be far enough off make it difficult to correlate.

All good info from you and @Spuds

I will likely start a build thread for my car this year even though it is pretty much built, just to document stuff like this. It may be backyard hackery but it's fun to play around with so why not.

[p1l0t]

Originally Posted by NoHaveMSG

That was my initial plan, I knew the data wouldn't be clean but to the point that Spuds brought up, it may be far enough off make it difficult to correlate.

All good info from you and @Spuds

I will likely start a build thread for my car this year even though it is pretty much built, just to document stuff like this. It may be backyard hackery but it's fun to play around with so why not.

My car is basically stock but I have thread just to keep track of everything, lol. (I have had other cars much more modified so starting a thread for the car is the first thing I do)

Sent from my SM-G975U using Tapatalk

[p1l0t]

Originally Posted by Spuds

FIFY. (Yes I know I am an ass)

You're not an ass, but actually you are wrong. See total (ram) air pressure vs static air pressure is was gives you the dynamic pressure. So when I said it compares ram air vs static I was 100% correct. If I said it measured dynamic pressure I would simply not mention the comparison (ratio).

Sent from my SM-G975U using Tapatalk

[Spuds]

Originally Posted by p1l0t

You're not an ass, but actually you are wrong. See total (ram) air pressure vs static air pressure is was gives you the dynamic pressure. So when I said it compares ram air vs static I was 100% correct. If I said it measured dynamic pressure I would simply not mention the comparison (ratio).

Sent from my SM-G975U using Tapatalk

Doh. Yes, total pressure is static+dynamic.

Now I'm just a dumbass lol. But really I should have known that since that's kind of my degree...

[p1l0t]

Originally Posted by Spuds

Doh. Yes, total pressure is static+dynamic.



Now I'm just a dumbass lol. But really I should have known that since that's kind of my degree...

I got a Master's in Aeronautical Science and I forgot probably 90% of it. Then again I chose to fly planes instead of some of the more involved jobs...

Sent from my SM-G975U using Tapatalk

[weederr33]

I'm in that mood today where I hate everyone and everything. That is all.

[p1l0t]

Originally Posted by weederr33

I'm in that mood today where I hate everyone and everything. That is all.

Don't get mad, get even.

Sent from my SM-G975U using Tapatalk

[nextcar]

Originally Posted by weederr33

I'm in that mood today where I hate everyone and everything. That is all.

But...