Mayfield
Gold Supporter
- Joined
- Oct 30, 2003
- Messages
- 2,256
- Location
- Avondale, Arizona
- Aircraft
- Aero SP AT-4 (Gobosh 700X), TAG Titanium Explorer
My friend Vance Breese's wonderfully written posts about his flights and the recent posts about a forum member landing his gyro, inspire me to start this discussion.
Timing is everything.
How high do I flare? How fast?
It depends!
What is our job when we land?
Our job is to arrest our descent with such precision that our main wheels touch the ground, softly, with almost no ground speed or vertical speed.
We do this by managing the energy state of the aircraft.
I know there are many ways to look at this energy state, so bear with me while I go over a little primer.
Let's assume we are approaching touchdown at 60 MPH at a 500 FPM rate of descent. That's 88 FPS forward and about 8.3 FPS vertically.
Just a glance at those numbers tells us that we are doing a power approach in our gyroplane. It's about a 10 to one slope. If we were power off and maintained 60 MPH airspeed our rate of descent would be about 1320 FPM if we maintain a 4 to 1 slope.
In both scenarios, it's our job to “use up” the energy of our descent to zero out horizontal and vertical velocity just as the main wheels touch.
When we pull back on the stick we both change the rotor thrust vector and, albeit temporarily, increase rotor thrust. We begin to use up the energy stored in the system.
Although I would like to pretend I can zero out horizontal and vertical velocity at the same time, I don't think that's a reasonable expectation.
Which one do we zero out first? The vertical velocity of course.
How fast do we pull back on the stick? It depends!
If we have a really good sense of how the energy exchange between vertical rate and rotor thrust change happens, we can do an exquisitely gentle pull starting quite high, 20 feet or more, and stop the sink a few inches to a couple of feet above the surface. It is imperative we do the initial pull gently or we will level off too high or balloon.
If we made a powered approach, we can now slowly reduce throttle even further. As throttle is reduced your kinesthetic senses will detect sink toward the surface. Your job, at this time is to arrest that sink with increasing back pressure on the stick. You want to pull just quickly enough to maintain the few inches of altitude as airspeed bleeds away.
If your timing is good you will run out of back stick and ground speed just as the main wheels touch. It's actually not very important if you have a little engine power still applied. The rapidly increasing drag has put you so far behind the power curve by now that the aircraft will land. If throttle is still applied at this time, reduce throttle to idle.
A power off approach is only different in that you need to arrest a greater descent rate. The flare may start higher, but still gently.
Now the disclaimers.
The “numbers” above are approximations. If you choose to apply any of these procedures, I encourage you to engage the many fine instructors on this forum. Flesh out and discuss these concepts. If we disagree, we can be civil.
I am absolutely not disagreeing with anything your instructors have taught you. They know you, your equipment, your skill level and aptitude.
The above paragraphs provide very broad-brush strokes.
I hope we can discuss "landing the gyro" and maybe get a little out of the discussion.
I have used several hundred words to say “Pull back on the stick just fast enough to level off. Continue back pressure at a rate that will maintain your altitude as airspeed bleeds away until the aircraft can't stay in the air.”
Jim
Timing is everything.
How high do I flare? How fast?
It depends!
What is our job when we land?
Our job is to arrest our descent with such precision that our main wheels touch the ground, softly, with almost no ground speed or vertical speed.
We do this by managing the energy state of the aircraft.
I know there are many ways to look at this energy state, so bear with me while I go over a little primer.
Let's assume we are approaching touchdown at 60 MPH at a 500 FPM rate of descent. That's 88 FPS forward and about 8.3 FPS vertically.
Just a glance at those numbers tells us that we are doing a power approach in our gyroplane. It's about a 10 to one slope. If we were power off and maintained 60 MPH airspeed our rate of descent would be about 1320 FPM if we maintain a 4 to 1 slope.
In both scenarios, it's our job to “use up” the energy of our descent to zero out horizontal and vertical velocity just as the main wheels touch.
When we pull back on the stick we both change the rotor thrust vector and, albeit temporarily, increase rotor thrust. We begin to use up the energy stored in the system.
Although I would like to pretend I can zero out horizontal and vertical velocity at the same time, I don't think that's a reasonable expectation.
Which one do we zero out first? The vertical velocity of course.
How fast do we pull back on the stick? It depends!
If we have a really good sense of how the energy exchange between vertical rate and rotor thrust change happens, we can do an exquisitely gentle pull starting quite high, 20 feet or more, and stop the sink a few inches to a couple of feet above the surface. It is imperative we do the initial pull gently or we will level off too high or balloon.
If we made a powered approach, we can now slowly reduce throttle even further. As throttle is reduced your kinesthetic senses will detect sink toward the surface. Your job, at this time is to arrest that sink with increasing back pressure on the stick. You want to pull just quickly enough to maintain the few inches of altitude as airspeed bleeds away.
If your timing is good you will run out of back stick and ground speed just as the main wheels touch. It's actually not very important if you have a little engine power still applied. The rapidly increasing drag has put you so far behind the power curve by now that the aircraft will land. If throttle is still applied at this time, reduce throttle to idle.
A power off approach is only different in that you need to arrest a greater descent rate. The flare may start higher, but still gently.
Now the disclaimers.
The “numbers” above are approximations. If you choose to apply any of these procedures, I encourage you to engage the many fine instructors on this forum. Flesh out and discuss these concepts. If we disagree, we can be civil.
I am absolutely not disagreeing with anything your instructors have taught you. They know you, your equipment, your skill level and aptitude.
The above paragraphs provide very broad-brush strokes.
I hope we can discuss "landing the gyro" and maybe get a little out of the discussion.
I have used several hundred words to say “Pull back on the stick just fast enough to level off. Continue back pressure at a rate that will maintain your altitude as airspeed bleeds away until the aircraft can't stay in the air.”
Jim
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