F15 AFM no flap simulation

[GGTharos]

The purpose of flaps at landing is to decrease airspeed at approach and landing AoA.

 

Descent rate remains the same per nm since you're flying on the same glideslope. In terms of time (feet/min), since you are travelling slower on the same glideslope, descent rate decreases.

[Chipwich]

The purpose of flaps at landing is to decrease airspeed at approach and landing AoA.

 

Descent rate remains the same per nm since you're flying on the same glideslope. In terms of time (feet/min), since you are travelling slower on the same glideslope, descent rate decreases.

 

 

https://www.faasafety.gov/files/gslac/courses/content/35/376/Use%20of%20Flaps.pdf

[GGTharos]

Quote from the very same text:

 

Never retract the flaps to correct for an undershoot, since

that will suddenly decrease the lift and cause the airplane to sink even more rapidly.

 

So, putting flaps down increases sink rate ... pulling flaps up increases sink rate. What's one to do with those flaps?

 

Your interpretation of what's written there is poor. You're conflating pilot technique for light aircraft with things that flaps actually do - which is decrease airspeed for a given AoA (or otherwise interpreted, reduce the stalling speed of the aircraft)

 

You're not getting a faster sink rate when you're going slower on the same glide slope.

 

The purpose of flaps is to decrease approach and landing speed for a given landing technique - from the physics standpoint, it increases wing lift and drag.

Edited September 6, 2016 by GGTharos

[GGTharos]

You, the pilot, control the glidepath. The glidepath thus remains the same, as per landing technique. If you want to discuss the physical effects of deploying flaps without controlling the aircraft, I think that's another discussion.

 

In case it still isn't clear, an F-15 approach is performed at 21 units AoA, with a 3 degree glideslope with or without flaps.

 

As a result, approach speed is reduced by a certain amount. You can do the math of the effect flaps have on descent rate yourselves in this case.

[Bushmanni]

I think that the point Chipwich was trying to make is that if you extend flaps, that the glide angle will become steeper if you maintain the same speed (and thrust setting).

If you want to steepen the glide with the help of flaps it can be assumed that thrust is already at idle and any amount of flap deflection will increase the ROD if you maintain the same speed.

 

You don't fly the plane with flaps but with elevator, rudder and ailerons. While it's true that you would need to descent (steer the plane into a steeper dive using previously mentioned control surfaces) steeper to maintain same airspeed at the same thrust setting flaps aren't built primarily for that purpose. While the pdf gives an interesting point about the effects of flaps it doesn't describe a landing technique. Interpreting it like that will make your life unnecessarily complicated.

[Bushmanni]

This was originally about the purpose of the flaps.