Coopere
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- Feb 11, 2015
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Ok looking to defer to someone with way more experience than me on the proper ,if any, short field and soft field technique for a Piper Aztec.
Reason? I'm looking to fly into an odd field. First 1000ft is paved ashfault remainder of 1350 is turf/grass. Total field length is 2350
Field elevation of 625 and the expected oat will be 15c
The kicker is the displaces threshold 27 is displaced 1000ft, 09 displaced 200...
Airport data below.
Rwy 09/27 2350x125 turf/asphalt
Rwy 27 first 1000x50 asphalt,
remainder 1350x125 turf Thld 27 displ
1000´ Thld 09 displ 200´
In writing this up I realize I may take some flak, I am well aware that this won't be possible on some days depending on temperature and weight but mostly due to winds.
A departure off 27 (ashfault then grass) should be possible provided good winds
Conversely a landing on 09 should be possible as well winds favouring. (Grass then ashfault)
Remembering training days in the 172 short field called for max power, brakes held, 10 degrees of flap (depends on 172 model) elevator control slightly tail low, climb speed 57kias until obstacles cleared then retract flaps slowly after reaching 60kias then accelerate to vy 79kias
The procedure above however amended to follow the speeds for the aztec would work on an ashfault runway, basically no flap max power brakes holding release rotate at 80mph climb out accelerating past blue line 102 for vx 107 mph until obsticals cleared then accelerate to vy 120 however their is no official short field technique in my aztec flight manual or Poh
One thing that is noted however only in the performance graph is take off over 50ft obstical is the following and it doesn't explain much.
Distance over 50ft obstical 0 degree flaps
Lift off speed 80mph
Barrier speed 97mph
0 wind
Paved level runway
Conversely in the 172 a soft field technique isn't published but from memory it was simply hold the control coloum full aft use as little brakes as possible get the aircraft airborne as soon as possible then accelerate in ground effect prior to climb out.
I don't think the above procedure at all works in the aztec due to the flying tail as apposed to a regular elevator in the 172. The stabilator in the Aztec can provide a tremendous amount of lift induced drag causing a braking effect effectively reducing the acceleration that is needed for liftoff. However one also doesn't want the nose wheel on the grass creating drag from that either.
I'm hoping someone can provide some insight on grass takeoffs and techniques used. I've read Some use 1/4 flaps however it clearly states in the flight manual 0 flaps for short field and I'm inclined to follow what's published as much as possible.
This will be a very difficult field to goto, if things don't look and feel right on the day of the trip I have no issues aborting and going elsewhere.
On the book numbers I've come up with a slightly conservative 1500ft ground roll, the issue I have is the transition from pavement to grass this will add distance for sure...
In looking at all the numbers the landing as with most times will be easier the takeoff however is far far more difficult and I'm aware that it might not be possible at all.
Thanks guys
Reason? I'm looking to fly into an odd field. First 1000ft is paved ashfault remainder of 1350 is turf/grass. Total field length is 2350
Field elevation of 625 and the expected oat will be 15c
The kicker is the displaces threshold 27 is displaced 1000ft, 09 displaced 200...
Airport data below.
Rwy 09/27 2350x125 turf/asphalt
Rwy 27 first 1000x50 asphalt,
remainder 1350x125 turf Thld 27 displ
1000´ Thld 09 displ 200´
In writing this up I realize I may take some flak, I am well aware that this won't be possible on some days depending on temperature and weight but mostly due to winds.
A departure off 27 (ashfault then grass) should be possible provided good winds
Conversely a landing on 09 should be possible as well winds favouring. (Grass then ashfault)
Remembering training days in the 172 short field called for max power, brakes held, 10 degrees of flap (depends on 172 model) elevator control slightly tail low, climb speed 57kias until obstacles cleared then retract flaps slowly after reaching 60kias then accelerate to vy 79kias
The procedure above however amended to follow the speeds for the aztec would work on an ashfault runway, basically no flap max power brakes holding release rotate at 80mph climb out accelerating past blue line 102 for vx 107 mph until obsticals cleared then accelerate to vy 120 however their is no official short field technique in my aztec flight manual or Poh
One thing that is noted however only in the performance graph is take off over 50ft obstical is the following and it doesn't explain much.
Distance over 50ft obstical 0 degree flaps
Lift off speed 80mph
Barrier speed 97mph
0 wind
Paved level runway
Conversely in the 172 a soft field technique isn't published but from memory it was simply hold the control coloum full aft use as little brakes as possible get the aircraft airborne as soon as possible then accelerate in ground effect prior to climb out.
I don't think the above procedure at all works in the aztec due to the flying tail as apposed to a regular elevator in the 172. The stabilator in the Aztec can provide a tremendous amount of lift induced drag causing a braking effect effectively reducing the acceleration that is needed for liftoff. However one also doesn't want the nose wheel on the grass creating drag from that either.
I'm hoping someone can provide some insight on grass takeoffs and techniques used. I've read Some use 1/4 flaps however it clearly states in the flight manual 0 flaps for short field and I'm inclined to follow what's published as much as possible.
This will be a very difficult field to goto, if things don't look and feel right on the day of the trip I have no issues aborting and going elsewhere.
On the book numbers I've come up with a slightly conservative 1500ft ground roll, the issue I have is the transition from pavement to grass this will add distance for sure...
In looking at all the numbers the landing as with most times will be easier the takeoff however is far far more difficult and I'm aware that it might not be possible at all.
Thanks guys
