- #1
Frodo
Gold Member
- 201
- 91
- TL;DR Summary
- Variation of propeller thrust as air flow varies from backwards to forwards
The Blackbird wind powered car travels directly downwind faster than the wind speed powering it. Typically a 10 mph wind from directly behind it will cause it to travel at about 30mph.
I am trying to analyse how the car accelerates from rest. I know how it travels faster than the wind speed so I do not need that explained.
When the car is stationary the wind coming from behind will act on the "frontal" area and apply a force so the car will begin moving if this force exceeds the resistance to motion.
Once the car moves the propeller rotates because it is driven from the wheels. The propeller is now rotating but the incident wind is from behind. I am interested in what thrust the propeller will be generating in this region.
I am therefore looking for a study showing the thrust produced by a propeller when the incident wind is from behind, and comparing it with the thrust produced when the incident wind is from the front.
I have searched the web and read a number of NACA reports but none tackles this question.
Thank you.
I am trying to analyse how the car accelerates from rest. I know how it travels faster than the wind speed so I do not need that explained.
When the car is stationary the wind coming from behind will act on the "frontal" area and apply a force so the car will begin moving if this force exceeds the resistance to motion.
Once the car moves the propeller rotates because it is driven from the wheels. The propeller is now rotating but the incident wind is from behind. I am interested in what thrust the propeller will be generating in this region.
I am therefore looking for a study showing the thrust produced by a propeller when the incident wind is from behind, and comparing it with the thrust produced when the incident wind is from the front.
I have searched the web and read a number of NACA reports but none tackles this question.
Thank you.