Variations in soft field landings

"Jim Carter" wrote in message
et...
back when we had 40 - 50 - or 60 degrees of flaps available we didn't
always raise them even for short field landings. At 60 degrees and full
back elevator the O-1 would almost hover to a landing, brakes were kind of
ornamental at times.

The point is it all depends on the aircraft you're flying, the surface
friction, and where you want to turn-off. There shouldn't be a pedantic
mantra that you follow regardless of circumstance.

--
Jim Carter
Rogers, Arkansas

B I N G O !

Plus what works in airplane A is likely to be very costly in airplane B...

Examples. In a Cessna 120, the best short field technique I've found is to
simply plant the mains as soon as you get down to the ground (and over the
threshold) and lean on the brakes. If you try to 3-point, all you are going
to do is float if you are even a teeny bit fast. In a Luscombe, as I
understand it, that technique will get you stopped quickly but cost you a
prop and engine overhaul. Try it in a Cessna 150 and you are going to
wheelborrow and stand a chance of doing some significant damage.

If you have a Johnsen bar for the flaps and fixed gear, it MIGHT make sense
to retract. If you have electric flaps that take 15 - 20 seconds to retract,
and the flap lever is right next to the gear - well - I could probably think
of dumber things to do, but I'd have to work at it.

Learn to fly whatever airplane you are flying. They all have their
differences. That's why there is more than one kind.

--
Geoff
The Sea Hawk at Wow Way d0t Com
remove spaces and make the obvious substitutions to reply by mail
When immigration is outlawed, only outlaws will immigrate.

"Robert M. Gary" wrote in message oups.com...
: On Apr 25, 5:20 pm, "Maxwell" wrote:
: "Maxwell" wrote in message
:
: m...
:
: I was taught to lift the flaps immediately upon touch down on soft field
: landings. My instructors stated getting more weight on the brakes as soon
: as possible, would facilitate a quicker stop than leaving the flaps down
: for drag, and loosing some braking power to the extra lift.
:
: However, during my last BFR, the instructor corrected me very sharply. He
: insisted you get more drag from the flaps by leaving them down until you
: slowed to taxi speed, than the benefit of more weight on the brakes.
:
: What is the general consensus of the group? Flaps up or down, after
: touchdown on a soft field landing?
:
: Yes, my mistake guy. I did mean short field landing.
:
: Well that makes more sense. Different POH's recommend flaps up or not
: touch the flaps. Getting the flaps up will make the landing shorter
: but has caused many pilots to accidently raise the gear, so many CFIs
: say don't touch anything on roll out. Personally, I raise the flaps
: because I take my Mooney to real soft fields in Mexico. However, for
: those that use it as an academic exercise it may be more important to
: make sure your student doesn't grab the gear switch (which is hard to
: stop as a CFII).
:
: -Robert, CFII
:


Raising the gear will definitely shorten the landing roll.... ;-)

Blueskies wrote:

Raising the gear will definitely shorten the landing roll.... ;-)

Technically though, when on the ground, you are not raising the gear; the
gear stays just where it is, more or less, on the ground. You are however
lowering the fuselage.

:-)

--Sylvain

Sylvain wrote:
You are however
lowering the fuselage.

Has a nasty habit of raising your premiums in the process.

Thus, I submit Gnu's Law, that insurance cost is inversely proportional
to height above ground.

TheSmokingGnu

On Wed, 25 Apr 2007 16:54:23 -0500, "Maxwell"
wrote:

I was taught to lift the flaps immediately upon touch down on soft field
landings. My instructors stated getting more weight on the brakes as soon as
possible, would facilitate a quicker stop than leaving the flaps down for
drag, and loosing some braking power to the extra lift.

However, during my last BFR, the instructor corrected me very sharply. He
insisted you get more drag from the flaps by leaving them down until you
slowed to taxi speed, than the benefit of more weight on the brakes.

What is the general consensus of the group? Flaps up or down, after
touchdown on a soft field landing?


Hopefully here won't be a consensus. It depends on the airplane,
pilot, and technique.

The short field landing which you are describing, rather than soft
field usually has a recommendation in the POH which may, or not give
the shortest landing possible including roll out. However that
landing was done using the best possible application of normal
techniques with a very good pilot who knew the specific make and model
far better than the average pilot.

One thing short field landings have in common is a STEEP final where
energy/speed is bled off in the round out. In some planes this means
carrying considerable power on the final just prior to the round out.
Dragging it in with the ability to set it down and stop on a postage
stamp is not a normal short field unless you are a bush pilot landing
on sand bars, or dragging it in over your neighbor's bean field. Even
then a good portion of the final (in ground effect) should be
considered as part of the landing.

There is one thing in normal short field landing I've heard with which
I disagree and that is holding the yoke back all the time. I plant
the mains on, immediately let the nose gear down, get on the brakes,
and THEN bring the yoke back again.

Something to remember in planes with electric flaps is the time it
takes to retract them and how much added lift you get during the
retraction. With most planes most of us are flying the last portion
of flap extension adds drag without adding lift. So when removing
flaps we remove drag, then add lift for a time before the flaps have
retraced enough to reduce the lift. I've found some planes where the
POH recommends raising the flaps can be almost brought to a stop
before the flaps are all the way up. That means in the latter portion
of the ground roll it didn't matter if the flaps were up or down. In
some of those cases raising the flaps adds lift right when you want to
get rid of it and removes drag right when it will do the most good.

One plane or rather group of planes where the retraction of the flaps
can be quite effective in shortening the rollout is the Cherokee
family that has the Johnson bar flaps (Mechanical). Actually it's the
only plane I've flown where the difference is quite noticeable.

"I believe" which is a personal opinion based only on my experience in
the specific 150s, 172s, Cherokees, Debonairs, and Bonanzas I've
flown, that it is possible to make the shortest landing possible by
leaving the flaps at full and a lot of practice. OTOH With the 150s
and 172s I doubt if most pilots are going to be able to see much if
any difference whether the flaps are raised or left down.

Roger (K8RI) wrote:


There is one thing in normal short field landing I've heard with which
I disagree and that is holding the yoke back all the time. I plant
the mains on, immediately let the nose gear down, get on the brakes,
and THEN bring the yoke back again.


Then you're too fast to start with. A short field landing is a
bang-bang play. Bang, the mains hit, then bang the nose wheel hits.
Stick position is irrelevant and won't really affect what happens with
the nosewheel because if you have your speed right any additional drag,
such as the mains hitting, means she's all done flying. The nose is
coming down and nothing short of a lot of power is going to change that.





Something to remember in planes with electric flaps is the time it
takes to retract them and how much added lift you get during the
retraction. With most planes most of us are flying the last portion
of flap extension adds drag without adding lift. So when removing
flaps we remove drag, then add lift for a time before the flaps have
retraced enough to reduce the lift.




Not correct. From full flaps, retracting any amount of flaps will
always reduce the total amount of lift the flaps are providing. On your
typical Cessna the majority of the lift comes in the first 20 degrees
with not a lot of added drag. But going from 20 to 40 degrees does add
lift, that's why the stall speed is lower at 40 flaps than at 20. So
reducing any flaps reduces lift, it raises the stall speed thereby
putting more weight on the wheels.

In article ,
"Blueskies" wrote:

"Robert M. Gary" wrote in message



Raising the gear will definitely shorten the landing roll.... ;-)

Trouble -- it will then take full power to taxi. ;)

Newps wrote:

I've found best performance to be a carrier type landing. Fly it into
the ground at minimum speed, as soon as you hit lock the brakes, stick
full back and hit the flap switch. Let up slightly on the brakes every
now and again, I've found just a little slippage is better than totally
locked. Non pavement only, of course.

Depends on the surface. If it is snow or sand, locking the wheels and
keeping them locked is best. If it is a harder surface that you can't
"plow" up, then incipient lock-up is best. Just like ABS on cars. It
works well on dry and wet pavement, but doesn't perform nearly as well
on snow or sand as compared to non-ABS brakes that can be locked.

Matt

Thus, I submit Gnu's Law, that insurance cost is inversely proportional to
height above ground.

Ooops. You mean directly proportional to the height above the ground.
--
Jim in NC

"Bob Gardner" wrote in message
news
It's the old "my instructor said..." story instead of reading the book.
The Airplane Flying Handbook says, on page 8-20, "If flaps are used, it is
generally inadvisable to retract them during the after-landing roll
because the need for flap retraction is usually less important than the
need for total concentration on maintaining full control of the airplane."

Gotta wonder (1) why the flaps-up instructor doesn't go by the book, and
(2) why you swallow his story without asking for documentation for his
method.


Gotta wonder what page Bob, my copy doesn't specify under short field
landings. And a lot of inquiring minds here seem to disagree.