Short Field Takeoffs

drgwentzel

Pre-takeoff checklist
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Flyers,

I was just wondering how the group feels about the process we are taught on short field takeoff's. I was never a fan of holding the brakes and going to full power before release. It always seemed to me that a good brisk rolling start from the taxiway and application of full power had more promise than the usual system.

At brake release the acceleration is lack-luster and anti-climatic on a good day and down right disappointing on average. The plane relucantly inches foward like a 90 year-old pushing himself out of a low sitting bed first thing in the morning.

This short field method is ubiquitous in our flight training from the very beginning of our instruction. It somehow evokes images and emotions in me that prior to this post were poorly understood.

The images are clear to me now, as is the headshaking smirk that always reveals itself on my face during this ceremony. Picture if you will: We mount our steed with anticipation and trepidation and line it up on the end of the runway. We breathe deeply and sense the shortness of the field, grandness of the trees in our path and a butterfly in our stomach.

As taught we dutifully set our flaps and press our feet firmly on the brakes. With one last inhalation we bring in full power and the engine obediently hollers to life. From outside the airplane the sight must be truly spectacular. The Lycoming’s 200 horses are roaring, growling, spitting and snorting. The airframe is shaking and shuddering. Like a wild stallion it rises up on its hind legs, whinnying and bucking. Its front extremity punches, jabs and hoof-paws at the turf demanding liberation to assault the runway and sky before it.

From within the cockpit something different is taking place. The 50-something pilot in the left seat is experiencing a more poignant response. There is a bit of nostalgia being played out before him. He is no longer the past-prime individual that entered this trembling contraption. He finds himself the 17 year-old boy that still lurks inside him, veiled from sight, like a black sheep brother that demands some explanation or apology. This youngster is not in an airplane, but strapped in the seat of his muscle car of the same era. His friends are outside waiting keenly and cheering him on as his left foot is pressed firmly on the brakes, while the opposite has the accelerator determinedly smashed against the floorboard. The engine is screaming and sneering, the car is trembling and the rear tires are protesting an ominous cry. On the release of the brakes, the car lurches forward, the occupant is pressed into the seatback and the G-forces provide the thrill that screaming tires, burning rubber and cheering spectators demand.

This musing and reminiscence rife and ripe with promise, expectation and desire never comes to fruition in our short field technique. But I do have to say that despite my disappointment on brake release, I must remember that unlike my intrepid Cessna, the 1972 Camero could never break its bond with the Earth.

Gene Wentzel – ‘71 Cessna Cardinal RG
 
With a Constant Speed prop, holding the brakes and running up to full power makes sense as the prop adjusts and changes pitch as the airplane picks up speed down the runway.

With a fixed pitch prop, you won't see full RPM until you're rolling.

When you're flying out of a very short field with a low powered airplane, you'll want every inch of runway coupled with a full power takeoff. If you run to full throttle with the brakes on, you'll find out if the engine's good at that high power setting.

In my old Chief the engine will sputter until warmed up (and the Lycoming engine manual suggests that the engine should be run a bit longer until it "no longer hesitates"). So I'll run it up full throttle and make sure I see and hear what I expect before commencing the takeoff roll.
 
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Get an observer, pick a point about halfway to your takeoff distance, and determine your IAS at that point using both methods. (also good practice for applying the "50-70 rule" in the real world--you should be seeing approximately 70% of your liftoff speed) Don't forget to hang your tailskid off the end of the runway for the "full power to brake release" method.

Or, count runway lights to your liftoff point (they're 200 feet each, btw).

My experience on my 1500-ft strip, with my extremely underpowered Maule is that there is a substantial difference, favoring the "full power to brake release" technique. By "substantial", I mean the difference between continuing the takeoff and having to abort due to lack of airspeed on a hot day.

Proper aircraft attitude makes a big difference as well...using a tail-low technique (which most people tend to recommend, for some reason) results in as much as a 300-ft increase in takeoff distance over bringing the tail up to a level attitude at the optimum time.

David
 
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Proper aircraft attitude makes a big difference as well...using a tail-low technique (which most people tend to recommend, for some reason) results in as much as a 300-ft increase in takeoff distance over bringing the tail up to a level attitude at the optimum time.

David

Really??

All I ever heard was to let the tail come up on its own -- too early and you don't have enough rudder authority, too late and you're dragging the ground.

:dunno:
 
Really??

All I ever heard was to let the tail come up on its own -- too early and you don't have enough rudder authority, too late and you're dragging the ground.

:dunno:

I think you would have pretty good rudder authority from the beginning of the roll with airflow from the prop providing it. It isn't the same as on landing when the engine is at or near idle.
 
Flyers,

I was just wondering how the group feels about the process we are taught on short field takeoff's.

...snip...

But I do have to say that despite my disappointment on brake release, I must remember that unlike my intrepid Cessna, the 1972 Camero could never break its bond with the Earth.

Gene Wentzel – ‘71 Cessna Cardinal RG
Beautiful.
 
Really??

All I ever heard was to let the tail come up on its own -- too early and you don't have enough rudder authority, too late and you're dragging the ground.

:dunno:
I think it varies from model to model...in my Maule (underpowered and under-winged), neutral elevator for a second or two (so I'm not adding drag with down elevator--a Maule tail is HEAVY), and then right up to a level attitude seems to work best.

What little I've flown in a Husky (plenty of power and wing) seems to indicate that a quick pop up to level attitude with almost immediate rotation will get you in the air the shortest, with a neutral elevator "floating" the tail (the technique recommended by the AFM, IIRC) a very close second with MUCH less effort. But I haven't spent a lot of time in the airplane, so I really can't speak with a lot of authority there.

A neighbor growing up (who passed away just last year at the age of 95, I think) used to give rides in an Aeronca C-3 (his first "factory" airplane) out of a square cow pasture...the key there was to get it up on one wheel along one fence line, make the turn along the other fence line, get it into ground effect, and bounce it over the pasture fence. Touched down on the other side about half the time, he said, but flew out of it from there.

I really don't think there's a "one size fits all" answer for max performance operations in taildraggers. Start with the manufacturer's recommendation, if there is one...otherwise the Airplane Flying Handbook says:

As the takeoff roll progresses, the
airplane’s pitch attitude and angle of attack should be
adjusted to that which results in the minimum amount
of drag and the quickest acceleration. The tail should
be allowed to rise off the ground slightly, then held in
this tail-low flight attitude until the proper lift-off or
rotation airspeed is attained. For the steepest climb-out
and best obstacle clearance, the airplane should be
allowed to roll with its full weight on the main wheels
and accelerated to the lift-off speed.
...which really leaves a LOT of room for interpretation.

Bottom line is that some serious experimentation in your airplane will likely yield substantial differences in takeoff length from one technique to another.
 
when i was flying a 7ECA citabria i found that a tail low method (which is recommended in the book) for takeoff resulted in significantly shorter takeoff distances than lifting the tail up to a "level" attitude and accelerating. In the Super Cub it didnt really matter, I don't think I was good enough to land anywhere short enough to make a difference on technique used to get out.
 
It always seemed to me that a good brisk rolling start from the taxiway and application of full power had more promise than the usual system.

I've never been in a truly short field with a taxiway :D.

Deb
 
I think it varies from model to model...

Bottom line is that some serious experimentation in your airplane will likely yield substantial differences in takeoff length from one technique to another.

Amen. Henry and I both fly Luscombes however, they are different models. He lifts the tail on take off on short fields because it's the configuration that will get him off the ground quicker.

I take off three point. It's the configuration that gets me off the ground quicker. In my airplane, the tailwheel will not come up until it's ready to fly anyway.

http://www.youtube.com/watch?v=5T-ts-FAgqo

This is not a true short field, and it's downhill, but it shows how the my Luscombe works in that takeoff configuration.

BTW, we don't hold the brakes either. They are only good up to about 1700 rpm. Henry's old Firestone Shinns wouldn't hold that much.

Deb
 
The FAA's short field technique sucks. They completely ignored the laws of physics when coming up with their "great" technique.
 
I was just wondering how the group feels about the process we are taught on short field takeoff's. I was never a fan of holding the brakes and going to full power before release.

I like to know I'm getting full static rpm, oil pressure and everything else
is looking good before I launch on a short field.

RT
 
The FAA's short field technique sucks. They completely ignored the laws of physics when coming up with their "great" technique.

Would you describe your technique, then?
 
I like to know I'm getting full static rpm, oil pressure and everything else
is looking good before I launch on a short field.

RT

Do you lean for max RPM?
 
I have thought about this, and wondered if rolling into the takeoff wouldn't provide more airspeed sooner.

Many years of physics classes have me thinking that every mph of velocity carried into the takeoff roll should reduce the takeoff time and distance.

I have never tested this theory, but I did see this video on youtube the other day. It seems the pilot of this Bo is a believer in the rolling takeoff.

http://www.youtube.com/watch?v=wE6_4vW1fxQ

I dunno. He seems to be moving pretty well at the 20 ft mark, and is near rotation speed by the time he passes the camera.

OTOH, perhaps the difference in takeoff time/location is so small, that the reward does not outweigh the risk of collapsing the nosegear under sideload stress, nor the fact that he almost put his wingtip in the trees, or the other Bonanza parked 1/2 way down the the runway.



Flyers,

I was just wondering how the group feels about the process we are taught on short field takeoff's. I was never a fan of holding the brakes and going to full power before release. It always seemed to me that a good brisk rolling start from the taxiway and application of full power had more promise than the usual system.
 
Not publicly.

Why, if it's way better than the FAA procedure?

I'm curious, because I'd like to know a procedure that works better. Then again I tend to fly out of long strips with planes that have enough power and aren't runway hogs, so it's never really an issue for me.
 
Why, if it's way better than the FAA procedure?

I'm curious, because I'd like to know a procedure that works better. Then again I tend to fly out of long strips with planes that have enough power and aren't runway hogs, so it's never really an issue for me.

Because, I know somewhere, somehow, someone will stumble upon this, not do exactly as I stated, and somehow I'll find myself in court.
 
Consider how fast your rolling taxi to takeoff is. Now consider how much distance it takes to accelerate to that speed. That's the maximum distance you can save. Now subtract from that the difference between being able to taxi out to the very edge of the runway, versus doing a rolling turn onto the runway, because you lose this.

Unless you're really planning on hauling ass around whatever final turn you need to make to get onto the runway, then I don't think you're saving a whole lot of distance by doing it.
-harry
 
OTOH, perhaps the difference in takeoff time/location is so small, that the reward does not outweigh the risk of collapsing the nosegear under sideload stress, nor the fact that he almost put his wingtip in the trees, or the other Bonanza parked 1/2 way down the the runway.

Consider how the Bonanza main gear deploys and how the fuel is fed in a Bo and you'll see that that guy is an accident waiting to happen.
 
Please explain to those of us that don't fly Bos.


Excessive side load on a gear that is designed to close inward is just dumb.

Bonanza tanks are rubber bladder cells -- at less than full amounts it would be possible to unport and disrupt the fuel supply (especially if the installation was imperfect, causing wrinkles in the material). Given how much is in the system (line, pump, etc) the uport would cause a nice power loss at about 100' AGL or so.
 
Looking at the performance charts (not the "Normal Procedure" section), I see that both my Warrior III and 172P manuals call for full power before brake release for a short-field takeoff. Could it possibly be that the instructors whose advice you so readily discard are following the manufacturer's recommendations?

Bob Gardner
 
Dan, I can see your point but... In my personal opinion I thought it was a well executed rolling takeoff. He was close to the parked plane as he zipped by but probably a good pilot as opposed to being lucky. IMHO

Ben, Flame suit on, Haas. :dunno:
 
I've never been in a truly short field with a taxiway :D.

Deb

+1. The shortest fields I've been in with my cherokee required back-taxi.
 
I like to know I'm getting full static rpm, oil pressure and everything else
is looking good before I launch on a short field.

RT

Why not check that part way into your takeoff roll when there's still plenty of room to stop? I'm not suggesting that checking this before brake release is wrong, just that IMO there's not much benefit either.
 
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Looking at the performance charts (not the "Normal Procedure" section), I see that both my Warrior III and 172P manuals call for full power before brake release for a short-field takeoff. Could it possibly be that the instructors whose advice you so readily discard are following the manufacturer's recommendations?

Bob Gardner

Perhaps the manufacturers need a remedial physics lesson on moments of intertia.
 
Excessive side load on a gear that is designed to close inward is just dumb.

Bonanza tanks are rubber bladder cells -- at less than full amounts it would be possible to unport and disrupt the fuel supply (especially if the installation was imperfect, causing wrinkles in the material). Given how much is in the system (line, pump, etc) the uport would cause a nice power loss at about 100' AGL or so.

Properly set up, the Bonanza gear will handle much greater side loads than a high power rolling turn on grass will generate, and IME they see much worse side loading when some pilots are landing. As to unporting the fuel tank, that issue can be eliminated by feeding the engine from the tank on the inside of the turn, something any Bonanza pilot well versed in turning takeoffs would be aware of and doing. And IMO the bladders themselves have nothing to do with this, the amount of dihedral and aspect ratio of the tanks are the pertinent factors. Finally, some Bonanzas have "baffled" tanks meaning that there is a small portion of the tank that's relatively isolated from the rest which holds fuel near the outlet even when lateral forces are pulling most of the fuel away.

That said, I'm not at all certain that a takeoff involving a 180 degree turn at the start would be more effective than a smaller (or no) turn and the answer might well depend on how soft the ground was as well as the density altitude. As someone else mentioned earlier, it would be interesting to run some tests to see how effective this is.

Also FWIW, most Bonanzas don't have enough power to get the prop off the low pitch stops until reaching around 30 KIAS so I don't see much advantage in waiting for the RPM to "stabilize" before releasing the brakes when starting aligned with the runway. This may not be true for Bonanza that have had engine upgrades (or other airplanes).
 
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Why not check that part way into your takeoff roll when there's still plenty of room to stop? I'm not suggesting that checking this before brake release is wrong, just that IMO there's not much benefit either.


If the field's that short, it's usually narrow with trees or other hazards nearby.

I'm monitoring the sounds and feel of the takeoff, but can't say I do a full engine monitor scan other than "green, top of the arc" (all I have is Oil temp & pressure and RPM). I'm usually a bit more concerned with keeping it straight and looking for my decision point.

Not the same as a runup actually looking at the gauges to get a more precise read.

:dunno:
 
Why not check that part way into your takeoff roll when there's still plenty of room to stop? I'm not suggesting that checking this before brake release is wrong, just that IMO there's not much benefit either.
If you're not making proper rpm or oil pressure, there's no sense in beginning the takeoff...I'm not suggesting NOT checking after brake release, but why even start a takeoff that you know you can't complete?
 
The reason the POH says to set the brakes and go to full power is because that is a condition that is KNOWN and easy to duplicate. There simply is no way you could provide performance charts if people were starting their takeoff roll with different levels of energy.

When it comes to actually departing as short as you can - it entirely depends on the situation. There are times where you can get a good run at the runway and have lots of energy that you wouldn't have had if you came to a stop. There are other times where you simply won't gain anything. There are some airplanes that make this easier. There are other airplanes I'd have no interest in throwing in lots of power while trying to align with the runway.

I tend to roll into the takeoff on a short field if I can find a good position that permits it. I glance at the oil pressure and RPM once the power comes up. At Gastons, for example, I have verified that I can get off the runway earlier IF I get a good angle on the runway from the 2nd set of airplanes. That said, I don't like doing it unless there aren't many people around and I really need that extra energy. Else, putting in full power while pointing at a bunch of people in lawn chairs isn't the best plan. If I don't need the energy I still roll onto the runway but don't throw in a bunch of power until I'm aligned.
 
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Properly set up, the Bonanza gear will handle much greater side loads than a high power rolling turn on grass will generate, and IME they see much worse side loading when some pilots are landing. As to unporting the fuel tank, that issue can be eliminated by feeding the engine from the tank on the inside of the turn, something any Bonanza pilot well versed in turning takeoffs would be aware of and doing. And IMO the bladders themselves have nothing to do with this, the amount of dihedral and aspect ratio of the tanks are the pertinent factors. Finally, some Bonanzas have "baffled" tanks meaning that there is a small portion of the tank that's relatively isolated from the rest which holds fuel near the outlet even when lateral forces are pulling most of the fuel away.


All good points -- but it depends on the field. All the grass fields around here (just west of the Alleghenies) are rough (and get rougher in late summer, early fall).

East of Blue Mountain, the grass fields are pillow soft.

Side load can be increased dramatically when any retractable hits a groundhog hole. The Bo gera is tough, no doubt, but it's meant to collapse in and up -- in the same direction the load will be pushing in a fast turn.

The Bonanzas I've flown have been the '47 -35 and a 1980 A36 with tip tanks. On both I was warned about fuel unporting. The E-185 had a strange fuel return setup that returned surplus fuel from the carb to the left tank. Thus all takeoffs were done with fuel on Left.
 
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This is most confusing...what angular rate concerns you?

Maybe MOI was the wrong term, but more the accelleration of something from a dead stop vs something already moving.
 
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