Bumped by Community user
Bumped by Community user
Bumped by Community user
Chris
• 133
• 5

I have an object that is launched from the side of a plane (it is a flare).

The question is: what does the flare do while it is proximate to the plane? Will it hit the tail?

After accounting for the motion of the aircraft, I have the motion of the flare decently understood and plotted, according to wind resistance without accounting for the propeller wash.

Then it occurs that the flare will be in the prop wash of the aircraft while it is in motion near the plane.

Understanding that the prop wash will be turbulent, and assuming that I find a way to estimate the wind speed of the prop wash, what will be the effect on the force of wind resistance due to the prop wash?

I.e., how will the turbulence of the prop wash mitigate the increased wind resistance due to the airspeed of the prop wash?

To expand on this, and the flexibility of the answer, the parameters are:

• The velocity of the prop wash is an estimate of the upper bound of the average velocity of the prop wash
• The purpose of this is to verify that an object coming out of the side of the plane will not hit the tail
• It is necessary simply that I establish an upper bound on what the wind resistance conditions are going to be, as I already have a code written for the position estimate, relative to the aircraft geometry, speed, altitude, etc.

My current solution is as follows (not ready to post as an answer):

1. Get an upper bound on power output of the engine (~1900 kilowatts for the turboprop in question here)
2. Multiply the watts by the reciprocal of the forward velocity of the aircraft and reciprocal of area affected by the propeller to get a force per sq meter
3. Solve for $$v_w$$ in the equation $$F = \rho v_w (v_w - v_o)$$$$F = \rho A_{prop} v_o (v_w - v_o)$$, which is a correction to the estimate in response 3 of the linked forum thread.
Chris
• 133
• 5

I have an object that is launched from the side of a plane (it is a flare).

The question is: what does the flare do while it is proximate to the plane? Will it hit the tail?

After accounting for the motion of the aircraft, I have the motion of the flare decently understood and plotted, according to wind resistance without accounting for the propeller wash.

Then it occurs that the flare will be in the prop wash of the aircraft while it is in motion near the plane.

Understanding that the prop wash will be turbulent, and assuming that I find a way to estimate the wind speed of the prop wash, what will be the effect on the force of wind resistance due to the prop wash?

I.e., how will the turbulence of the prop wash mitigate the increased wind resistance due to the airspeed of the prop wash?

To expand on this, and the flexibility of the answer, the parameters are:

• The velocity of the prop wash is an estimate of the upper bound of the average velocity of the prop wash
• The purpose of this is to verify that an object coming out of the side of the plane will not hit the tail
• It is necessary simply that I establish an upper bound on what the wind resistance conditions are going to be, as I already have a code written for the position estimate, relative to the aircraft geometry, speed, altitude, etc.

My current solution is as follows (not ready to post as an answer):

1. Get an upper bound on power output of the engine (1900 watts~1900 kilowatts for the turboprop in question here)
2. Multiply the watts by the reciprocal of the forward velocity of the aircraft and reciprocal of area affected by the propeller to get a force per sq meter
3. Solve for $$v_w$$ in the equation $$F = \rho v_w (v_w - v_o)$$, which is the estimate in response 3 of the linked forum thread.
Chris
• 133
• 5

I have an object that is launched from the side of a plane (it is a flare).

The question is: what does the flare do while it is proximate to the plane? Will it hit the tail?

After accounting for the motion of the aircraft, I have the motion of the flare decently understood and plotted, according to wind resistance without accounting for the propeller wash.

Then it occurs that the flare will be in the prop wash of the aircraft while it is in motion near the plane.

Understanding that the prop wash will be turbulent, and assuming that I find a way to estimate the wind speed of the prop wash, what will be the effect on the force of wind resistance due to the prop wash?

I.e., how will the turbulence of the prop wash mitigate the increased wind resistance due to the airspeed of the prop wash?

To expand on this, and the flexibility of the answer, the parameters are:

• The velocity of the prop wash is an estimate of the upper bound of the average velocity of the prop wash
• The purpose of this is to verify that an object coming out of the side of the plane will not hit the tail
• It is necessary simply that I establish an upper bound on what the wind resistance conditions are going to be, as I already have a code written for the position estimate.

My current solution is as follows (update in progressnot ready to post as an answer):

1. Get an upper bound on power output of the engine (1900 watts for the turboprop in question here)
2. Multiply the watts by the reciprocal of the forward velocity of the aircraft to get a force
3. Solve for $$v_w$$ in the equation $$F = \rho v_w (v_w - v_o)$$, which is the estimate in response 3 of the linked forum thread.