Short Field Takeoff (any bush pilot around?)

[LV-ARG]

I'm trying to get some opinions based mainly on actual flight experience rather than "book says" kind of responses. Im not saying their are wrong or we shoulnt fly by them but I'm simply not what im looking for now.

The thing that actually pushed me into creating this thread was after watching this video http://www.flyaoamedia.com/blog/aviation/my-scariest-moment-as-a-pilot/

Bonanza, 3 on board, half tanks, Approach flaps I believe.

I'm trying to figure out what is the most efficient thecnique for sorting obstacles at the end of the runway. My understanding about this is that climb performance [ROC & Climb angle] will suffer (diminish) when using any flap setting other than "up". The purpose of using flaps on short field takeoff is only for shortening the TO run (good for short grass strip with no obstacles ahead, or even concrete with no obstacles). But in the case of a concrete runway with trees at the end, wouldnt have been better to T/O with the flaps up?

What would you advise for a short grass strip with trees at the end? I think the standard soft field landing technique (say 10º for a 172) combined with rasing the flaps on ground effect after accelerating to no flaps Vx would give you the best chance to sorting ostacles at the end. Grass certainly adds a good amount of drag and takeoff run, so the sooner we lift, the sooner well experience a faster acceleration. So far so good, but after reaching Vx on ground effect if flaps are detrimental for climb performance, why wouldnt you raise them?. Of course, you have got to be on your toes to counteract the initial sinking of the airplane as you raise them, but in the overall takeoff woulnt it be better for clearing obstacles? Anyone ever tried this?, dont discuss if this is good or bad airmanship or flying technique, this is just a performance issue.

Im also interested in opinions about rolling takeoff vs full power on the brakes for short field. Any insight from guys operating consistently on short strips would be really appreciated.

 

[elmetal]

op:

 

[Mike H]

What does the POH say? Do it that way

 

[casey]

What would you advise for a short grass strip with trees at the end? I think the standard soft field landing technique (say 10º for a 172) combined with rasing the flaps on ground effect after accelerating to no flaps Vx would give you the best chance to sorting ostacles at the end.

pretty much the exact opposite of this. Try it sometime on a long enough runway that you can lift off and then land and stop. Raising the flaps in ground effect after liftoff is going to put you right back on the runway.

 

[mhcasey]

Always follow what the manual says.

But some food for thought...my understanding is that you want to get the most excess thrust in the quickest possible time. Typically that means accelerating on the runway to Vx (max excess thrust) and rotating/increasing pitch to maintain that. In a typical tricycle, a 3 point attitude will probably get you there the fastest. I kind of doubt that is true for a daildragger with tundra tires or a float plane. The condition of the runway (or beach, or grass, or whatever) will significantly affect drag.

Flap settings should always be in accordance with the flight manual. As an example, if I'm in ground effect with takeoff flaps flying speed in the T-38, if I suddenly retract the flaps I'm probably either going to abruptly impact the ground, or be waiting a hell of a long time in ground effect to get no flap flying airspeed, so I'll probably abruptly slam into the obstacle at the end of the runway.

 

[Cessnaflyer]

I've been to this airport and it isn't a very difficult airport. I did notice though that the windsock was showing a tailwind as they went buy it. That could have been the majority of the mistake.

 

[MikeD]

As an example, if I'm in ground effect with takeoff flaps flying speed in the T-38, if I suddenly retract the flaps I'm probably either going to abruptly impact the ground, or be waiting a hell of a long time in ground effect to get no flap flying airspeed, so I'll probably abruptly slam into the obstacle at the end of the runway.

You'd be waiting a bit, but not too long. AB takes care of that. Hence why the gear and flaps have to come up quickly on takeoff what with the acceleration.

 

[Cessnaflyer]

One thing I noticed on watching it again is that they retracted the gear before clear of obstacles. The Bonanza I flew the POH said that for short-field takeoff the gear was to remain extended until clear of obstacles. This is most likely because of the extra drag caused by the gear doors opening while the gear is retracting. The single engine Cessna's also have similar procedures to keep the gear hanging until clear.

 

[SmoothLanderJ]

I've been to this airport and it isn't a very difficult airport. I did notice though that the windsock was showing a tailwind as they went buy it. That could have been the majority of the mistake.

That was a close one! Good thing they can laugh about it now...

 

[ppragman]

I'm trying to get some opinions based mainly on actual flight experience rather than "book says" kind of responses. Im not saying their are wrong or we shoulnt fly by them but I'm simply not what im looking for now.

The thing that actually pushed me into creating this thread was after watching this video http://www.flyaoamedia.com/blog/aviation/my-scariest-moment-as-a-pilot/

Bonanza, 3 on board, half tanks, Approach flaps I believe.

I'm trying to figure out what is the most efficient thecnique for sorting obstacles at the end of the runway. My understanding about this is that climb performance [ROC & Climb angle] will suffer (diminish) when using any flap setting other than "up". The purpose of using flaps on short field takeoff is only for shortening the TO run (good for short grass strip with no obstacles ahead, or even concrete with no obstacles). But in the case of a concrete runway with trees at the end, wouldnt have been better to T/O with the flaps up?

What would you advise for a short grass strip with trees at the end? I think the standard soft field landing technique (say 10º for a 172) combined with rasing the flaps on ground effect after accelerating to no flaps Vx would give you the best chance to sorting ostacles at the end. Grass certainly adds a good amount of drag and takeoff run, so the sooner we lift, the sooner well experience a faster acceleration. So far so good, but after reaching Vx on ground effect if flaps are detrimental for climb performance, why wouldnt you raise them?. Of course, you have got to be on your toes to counteract the initial sinking of the airplane as you raise them, but in the overall takeoff woulnt it be better for clearing obstacles? Anyone ever tried this?, dont discuss if this is good or bad airmanship or flying technique, this is just a performance issue.

Im also interested in opinions about rolling takeoff vs full power on the brakes for short field. Any insight from guys operating consistently on short strips would be really appreciated.

Ex-Bushrat here

Ok, in my experience, your best bet for clearing the proverbial obstacle is to get the nose wheel about an inch off the ground during the takeoff roll with the flaps in the takeoff setting-so hold full back pressure until you feel the nose rise an inch then provide forward pressure to keep the nose wheel at an inch. If you have manual flaps (because otherwise its too difficult to do with electric flaps) you can go to full flaps as soon as you're right below flying speed, then with a dash of back pressure and the application of full flaps you can break ground. Now the next part is critical, you want to stay as close to the ground as possible and get those flaps out as rapidly as possible. As soon as you break ground, your airspeed will rapidly increase (those tires cause quite a lot friction, more than you'd think), so work your flaps out to maintain a constant distance above the runway, aim for Vx, then fly Vx until the obstacles are cleared, then retract the flaps.

With electrically actuated flaps (at least this is what I did in the 207 in kodiak) select the flap setting that is recommended by the manufacturer for short field performance. Then, pull the nosewheel off the ground an inch during the roll, then leave it there until speed is starting into the white arc, gently rotate and remain in ground effect to accelerate. After starting your climbout (once you've got to Vx), if you need to clear the trees at the end and you can tell you're not going to make it, go to full flaps, or some intermediate flap setting some distance after realizing you won't make it but before hitting the trees to eke it over the trees. Make sure there's some lower terrain (like a river or something) beyond the trees that you can dive down onto in order to ovoid being in slow flight over tall trees at 100'.

The technique of pulling the nosewheel off the ground an inch during the roll can be dangerous because if you over rotate, the increase in drag will greatly increase the ground roll. Not good. I've played with this quite extensively in the last 2000hrs or so in the PA32, 207 and 206, and these are my conclusion for those airplanes. As for the manual, the manual may or may not provide the best technique in light singles. The manual's recommendations are just a starting point. Remember, the test pilot flying the thing for engineers did everything in a brand new, unmodified light aircraft and interpolated the rest. Additionally, the tires didn't have to last that long between changes. Also remember that the techniques and procedures outlined in the AFM aren't an exact science, there's wide scale interpolations going on in there, and actual real world performance may be quite different from what the manufacturer predicts. In my experience, I've only had a few airplanes that would perform better than what the manufacturer predicted in a few instances. The stock early model 206, and the 207 with the STOL kit were the only airplanes where you could consistently beat engineered performance data (the other airplanes I've flown you could do it, but at least I could never do it consistently enough to bet my life on it. My advice? Go out to the airport, and try out the best techniques that you can do in the airplane you are flying. Write it all down, write down the Denalt for the day, write down what the manual predicts, then write down what you can do. Sometimes you can do better, sometimes you do worse, just make sure you're consistent with whatever super short field you do.

You've got to practice this stuff, do it with various load configurations and various settings. Find what you feel comfortable with, and don't do anything until you know what you're going to do.

As for the application of power, it depends, but my all around favorite technique for both pavement and for softfields is to taxi back to the numbers and go to full power in the turn to line up. This can add a bit of sideload, so make sure your airplane can do it (most cessna singles can).

 

[LV-ARG]

Ex-Bushrat here

Ok, in my experience, your best bet for clearing the proverbial obstacle is to get the nose wheel about an inch off the ground during the takeoff roll with the flaps in the takeoff setting-so hold full back pressure until you feel the nose rise an inch then provide forward pressure to keep the nose wheel at an inch. If you have manual flaps (because otherwise its too difficult to do with electric flaps) you can go to full flaps as soon as you're right below flying speed, then with a dash of back pressure and the application of full flaps you can break ground. Now the next part is critical, you want to stay as close to the ground as possible and get those flaps out as rapidly as possible. As soon as you break ground, your airspeed will rapidly increase (those tires cause quite a lot friction, more than you'd think), so work your flaps out to maintain a constant distance above the runway, aim for Vx, then fly Vx until the obstacles are cleared, then retract the flaps.

With electrically actuated flaps (at least this is what I did in the 207 in kodiak) select the flap setting that is recommended by the manufacturer for short field performance. Then, pull the nosewheel off the ground an inch during the roll, then leave it there until speed is starting into the white arc, gently rotate and remain in ground effect to accelerate. After starting your climbout (once you've got to Vx), if you need to clear the trees at the end and you can tell you're not going to make it, go to full flaps, or some intermediate flap setting some distance after realizing you won't make it but before hitting the trees to eke it over the trees. Make sure there's some lower terrain (like a river or something) beyond the trees that you can dive down onto in order to ovoid being in slow flight over tall trees at 100'.

The technique of pulling the nosewheel off the ground an inch during the roll can be dangerous because if you over rotate, the increase in drag will greatly increase the ground roll. Not good. I've played with this quite extensively in the last 2000hrs or so in the PA32, 207 and 206, and these are my conclusion for those airplanes. As for the manual, the manual may or may not provide the best technique in light singles. The manual's recommendations are just a starting point. Remember, the test pilot flying the thing for engineers did everything in a brand new, unmodified light aircraft and interpolated the rest. Additionally, the tires didn't have to last that long between changes. Also remember that the techniques and procedures outlined in the AFM aren't an exact science, there's wide scale interpolations going on in there, and actual real world performance may be quite different from what the manufacturer predicts. In my experience, I've only had a few airplanes that would perform better than what the manufacturer predicted in a few instances. The stock early model 206, and the 207 with the STOL kit were the only airplanes where you could consistently beat engineered performance data (the other airplanes I've flown you could do it, but at least I could never do it consistently enough to bet my life on it. My advice? Go out to the airport, and try out the best techniques that you can do in the airplane you are flying. Write it all down, write down the Denalt for the day, write down what the manual predicts, then write down what you can do. Sometimes you can do better, sometimes you do worse, just make sure you're consistent with whatever super short field you do.

You've got to practice this stuff, do it with various load configurations and various settings. Find what you feel comfortable with, and don't do anything until you know what you're going to do.

As for the application of power, it depends, but my all around favorite technique for both pavement and for softfields is to taxi back to the numbers and go to full power in the turn to line up. This can add a bit of sideload, so make sure your airplane can do it (most cessna singles can).

hey, thanks a lot for your response.

Any opinion or thoughts about a situation where it would be advisable to use A) over B)?
a) Accelerating on ground effect to an airspeed higher than Vx and zooming over the obstacle at the last moment vs the standard and well known b) Accelerating to Vx on ground effect and then climbing at Vx?

I remember being told by a FI that manual flaps had the advantage you could go from the approved takeoff setting to some higher flap deflection by momentarily yanking the flap lever and allowing the airplane to "jump" off a very muddy or "heavy" field. So of course Ive never seen such a soft field technique described in any POH, but it might work and (again) im just trying to get insight from actual flight experience.

Side note: I want to make myself clear one thing. I only fly by the book and use the techniques outlined in there because I do not know any better. However, I'm interested in knowing if there are better techniques that simply arent pubished on the POHs maybe due to liability related stuff.

 

[Low&Slow]

I did notice though that the windsock was showing a tailwind as they went buy it.

No, they definitely had a headwind.
In the beginning of the clip, as they taxi towards the turnaround end of the runway, the grass and trees appear to be blowing away from them, opposite the direction of departure. When they turn around and get into position and hold, you can see a small flag in front of a big pine tree on the right side of the runway that is indicating a headwind of ~18-20 kts, and there is also a sock on the roof of a building a little bit further to the right of the flag that is swinging to and from a direct headwind and a crosswind headwind. As they begin to roll down the runway, there is another windsock about 1/2 - 3/4 of the way down the runway that is also indicating a headwind.

 

[tgrayson]

Any opinion or thoughts about a situation where it would be advisable to use A) over B)?
a) Accelerating on ground effect to an airspeed higher than Vx and zooming over the obstacle at the last moment vs the standard and well known b) Accelerating to Vx on ground effect and then climbing at Vx?

NACA (pre-NASA) tested the zooming takeoff many year ago, but didn't find that it held any advantage over the takeoff at MCA, at least when the obstacle was close in. And it was more sensitive to pilot technique than the MCA takeoff.

 

[boondr]

You could try this method

[YT]UxfpGPWtoOY[/YT]

 

[Cessnaflyer]

No, they definitely had a headwind.
In the beginning of the clip, as they taxi towards the turnaround end of the runway, the grass and trees appear to be blowing away from them, opposite the direction of departure. When they turn around and get into position and hold, you can see a small flag in front of a big pine tree on the right side of the runway that is indicating a headwind of ~18-20 kts, and there is also a sock on the roof of a building a little bit further to the right of the flag that is swinging to and from a direct headwind and a crosswind headwind. As they begin to roll down the runway, there is another windsock about 1/2 - 3/4 of the way down the runway that is also indicating a headwind.

After watching again yeah I see they had a headwind. Looks like it just must have been the wind coming from down the ridge to the left of the aircraft keeping them down.

Here is the airport they took off from. http://skyvector.com/?ll=48.531188058919106,-121.7575945361513&chart=1&zoom=1

 

[cmill]

hey, thanks a lot for your response.

Any opinion or thoughts about a situation where it would be advisable to use A) over B)?
a) Accelerating on ground effect to an airspeed higher than Vx and zooming over the obstacle at the last moment vs the standard and well known b) Accelerating to Vx on ground effect and then climbing at Vx?

I remember being told by a FI that manual flaps had the advantage you could go from the approved takeoff setting to some higher flap deflection by momentarily yanking the flap lever and allowing the airplane to "jump" off a very muddy or "heavy" field. So of course Ive never seen such a soft field technique described in any POH, but it might work and (again) im just trying to get insight from actual flight experience.

Side note: I want to make myself clear one thing. I only fly by the book and use the techniques outlined in there because I do not know any better. However, I'm interested in knowing if there are better techniques that simply arent pubished on the POHs maybe due to liability related stuff.

The general technique we use on floats, is that you're better off flying it in the air than trying to drive it on the ground. If the plane is ready to fly then we use the yank the flaps technique. We'll do our take off roll with flaps 20, and if we absolutely have to get off and we dont have the room, we'll yank them to 40 and pull back on the yolk at the same time. If things are very dire we'll climb out at Vx. Its very hard on the plane, so we dont do it all that often.

Floats and wheels are different, but the concept is the same. You're better off climbing in the air than building up speed on the ground. Using less runway means more time in the air. The big difference between the two is that a plane on floats will hit a certain speed and not go any faster, due to the suction of the water. A heavy plane, poor technique, high temps, or any combo of, could cause a plane to never leave the water, so it becomes necessary to force it into the air. I dont have a lot of experience with single on short paved strips, but ive always been told to get the thing in the air and climb climb climb.

On a side note, we fly a baron and a navajo out of our strip (3200 ft) and we keep it on the ground as long as possible, but there are other considerations working into that.

 

[FlyGuy9k4]

Holy crap to that video haha.

Funniest part- 1:30- "OK- things we will NOT be doing again".... i've had a few of those moments, so it's ok to laugh a bit ... now. lol

:beer:

 

[LV-ARG]

NACA (pre-NASA) tested the zooming takeoff many year ago, but didn't find that it held any advantage over the takeoff at MCA, at least when the obstacle was close in. And it was more sensitive to pilot technique than the MCA takeoff.

Do you have any document or report about that study?

My thought process on why staying on ground effect a little bit more than whats required to fly off safely may be better is as follows:

Accelerating to a point somewhat faster than Vx (maybe Vy+5) could mean that the airplane has acquired more energy (kinetic + potential) than it would have done if a climb would have been started after reaching Vx in the same time frame. Ground effect allows for the airplane to accelerate faster (and even faster below Vy when induced drag is predominant), so why not take advantage of that increased peformance? Of course cruising at 3ft for a very long time wont do any good because its all about parasitic drag at higher speeds, and you would be using too much horizontal distance without really building too much energy (accelerating from 80 to 85 kts will use a whole lot of runway) but maybe accelerating to Vy, zooming, and then climbing at Vx could be better.