Chandelle, speaking of tight turns

wrote in message
ups.com...

It was a long time ago, but I seem to remember being in an Aerobat and
started a loop by diving and getting to maybe 140 kts before the pilot
pulled back. The question nagging at me is, if in something like an
Arrrow or a Mooney, if you were in a cruise at 140 knots would you
have enough speed to pull back into a half loop to make a fast 180
degree change in turn in a tight space?

I suppose I could calculate if one maintained 2 gs worth of
backpressure what would happen (it would be a funny half loop, turn
radius would get tighter and tighter as speed decreases and gravity
started pulling at the tail instead of at the wheels, but real life
experience is better than calculations, if anyone has such experience.


Assuming 140 knots and full power, I think most 4 place singles could
complete an eliptical loop. Your right, maintaining back pressure and
tighting the radius around the top would be necessary, but it could save
your butt in a box canyon or downtown NY.

I have actually done it in a 150, 172 and 182, no problem. But don't try it
without a real emergency or the proper training and equipment. It can also
kill some gyros.

when you did it, did you wait until manovering speed before pulling
all the way back? I'd worry, in the Mooney, if the pilot in command
(he loves being called that) pulled back to the stops at cruise. If
you kept your wits about you, I'd guess firm back until I think 130
knots, then to the aft limit in that airplane, would probably only
break a gyro or two, and not the backbone of the airplane. I don't
know if its gyros are rated for more than 60 degrees back or pitch.

I think the numbers would work out that we'd be well above stall at
the top still pulling positive gees, then a roll to upright, with
altitude in the bank. Be fun to try it in a simulator, but my personal
PIC would not do it in the airplane unless there was building in front
of him.

wrote in message
oups.com...
when you did it, did you wait until manovering speed before pulling
all the way back? I'd worry, in the Mooney, if the pilot in command
(he loves being called that) pulled back to the stops at cruise. If
you kept your wits about you, I'd guess firm back until I think 130
knots, then to the aft limit in that airplane, would probably only
break a gyro or two, and not the backbone of the airplane. I don't
know if its gyros are rated for more than 60 degrees back or pitch.

First things first, don't over stress the aircraft under any circumstances,
it shouldn't be necessary. You shouldn't need more than 2.5 Gs max, if that
much. But keep the Gs on. As the aircraft slows, maintaining those Gs
assures you the tightest possible loop radius, and is the quickest way over
the top. In this case, unlike demonstration aerobatics, you want an
elliptical loop. You shouldn't hit the stops until you get very near the
top, and very slow, if even then. Nine times out of ten these days, you
won't hurt the gyros, but there is no guarantee unless they are designed for
such duty or can be caged.


I think the numbers would work out that we'd be well above stall at
the top still pulling positive gees, then a roll to upright, with
altitude in the bank. Be fun to try it in a simulator, but my personal
PIC would not do it in the airplane unless there was building in front
of him.


I'd recommend some fundamental aerobatic training to ALL pilots. Just make
sure you have the proper equipment, and a good instructor. Nothing can
prepare you more for the unexpected, and make you feel more at easy during
your routine piloting. And an Immelmann as you describe, is a good move to
practice often.

The issue would be knowing the required airspeed in level flight to
have enough energy to get to the top of the loop without having the
airplane fall out of the sky. It seems to me, based on no experience,
I'd want to see the yoke pulled back as far and as fast as the
airframe can tolerate m-- that's why I suggested a couple or 3 gees
until manouvering speed, then all the way back. It would keep the
loop's quasi diameter as small as possible, it would be egg shaped
with lot tighter radius near the top, but I think it would be better
to have airspeed, not altitude, when you're almost topping out and
want to roll upright.

I'll offer to buy he who likes to be my personal pic some time in a
rated airplane with an instructor to have some fun with this. It's
been 20 years since he's been upside down in an airplane.

His flying habit, in real life, is to go everywhere under instrument
flight rules, which pretty much keeps him (and me) out of canyons. As
his personal SIC I can tell you I know what a sectional looks like,
but like enroute charts a lot better, and sure like to fly uncoupled
ILS approaches from the right seat. I do wonder what it would be like
to have the airspeed, GS and LOC needles in front of you, rather than
way over to the left. If I was in the left seat it would take a while
before I'd stop including the left wing in my scan ("Yes, the red nav
light is on, dammit!").

Thanks for your insights. I suppose thinking about these things is
worth doing, even for experienced pilots.

Tina

wrote in message
oups.com...
The issue would be knowing the required airspeed in level flight to
have enough energy to get to the top of the loop without having the
airplane fall out of the sky. It seems to me, based on no experience,
I'd want to see the yoke pulled back as far and as fast as the
airframe can tolerate m-- that's why I suggested a couple or 3 gees
until manouvering speed, then all the way back. It would keep the
loop's quasi diameter as small as possible, it would be egg shaped
with lot tighter radius near the top, but I think it would be better
to have airspeed, not altitude, when you're almost topping out and
want to roll upright.

The slower and closer you get to the top, the faster you can bring the nose
over. That's what elliptical is all about. And for the purpose we're
discussing, you really don't need to do your roll at the top. You have
already changed directions 180 degrees, you could do your roll on the
vertical down line.


I'll offer to buy he who likes to be my personal pic some time in a
rated airplane with an instructor to have some fun with this. It's
been 20 years since he's been upside down in an airplane.

I would recommend it for BOTH of you. With good equipment, and quality
instruction, it's a good experience for any pilot, and a lot of fun as well.


His flying habit, in real life, is to go everywhere under instrument
flight rules, which pretty much keeps him (and me) out of canyons. As
his personal SIC I can tell you I know what a sectional looks like,
but like enroute charts a lot better, and sure like to fly uncoupled
ILS approaches from the right seat. I do wonder what it would be like
to have the airspeed, GS and LOC needles in front of you, rather than
way over to the left. If I was in the left seat it would take a while
before I'd stop including the left wing in my scan ("Yes, the red nav
light is on, dammit!").

Thanks for your insights. I suppose thinking about these things is
worth doing, even for experienced pilots.

Tina

"Maxwell" wrote in message
...

wrote in message
oups.com...
when you did it, did you wait until manovering speed before pulling
all the way back? I'd worry, in the Mooney, if the pilot in command
(he loves being called that) pulled back to the stops at cruise. If
you kept your wits about you, I'd guess firm back until I think 130
knots, then to the aft limit in that airplane, would probably only
break a gyro or two, and not the backbone of the airplane. I don't
know if its gyros are rated for more than 60 degrees back or pitch.

First things first, don't over stress the aircraft under any
circumstances, it shouldn't be necessary. You shouldn't need more than 2.5
Gs max, if that much. But keep the Gs on. As the aircraft slows,
maintaining those Gs assures you the tightest possible loop radius, and is
the quickest way over the top. In this case, unlike demonstration
aerobatics, you want an elliptical loop. You shouldn't hit the stops
until you get very near the top, and very slow, if even then. Nine times
out of ten these days, you won't hurt the gyros, but there is no guarantee
unless they are designed for such duty or can be caged.

I would offer a different opinion... My big fear with new acro pilots is the
inverted accelerated stall. A 140 knot loop in an Arrow or Mooney is going
to get slow on top. Probably very close to stall speed. The way to keep the
speed higher at the top of the loop is with a fairly aggressive pull at the
beginning of the loop - say 3.5 g's, easing off as airspeed slows. Trying to
use the elevator to tighten the loop at the top is likely to result in a
stall, and possible inverted spin.

For what it is worth, I often float over the top of a loop at 60 knots,
which is about 10 knots above stall speed. At that point, the elevator is
more or less neutral, and the airplane is performing a -2g arc. One of the
g's comes from aerodynamic lift and the other comes from gravity... That's
only a .5 G different arc than the beginning of the loop, which was a 2.5 g
arc: 3.5 aerodynamic g's in the "up" direction minus 1 g from gravity...

KB

Kyle Boatright wrote:
"Maxwell" wrote in message
...
wrote in message
oups.com...
when you did it, did you wait until manovering speed before pulling
all the way back? I'd worry, in the Mooney, if the pilot in command
(he loves being called that) pulled back to the stops at cruise. If
you kept your wits about you, I'd guess firm back until I think 130
knots, then to the aft limit in that airplane, would probably only
break a gyro or two, and not the backbone of the airplane. I don't
know if its gyros are rated for more than 60 degrees back or pitch.
First things first, don't over stress the aircraft under any
circumstances, it shouldn't be necessary. You shouldn't need more than 2.5
Gs max, if that much. But keep the Gs on. As the aircraft slows,
maintaining those Gs assures you the tightest possible loop radius, and is
the quickest way over the top. In this case, unlike demonstration
aerobatics, you want an elliptical loop. You shouldn't hit the stops
until you get very near the top, and very slow, if even then. Nine times
out of ten these days, you won't hurt the gyros, but there is no guarantee
unless they are designed for such duty or can be caged.

I would offer a different opinion... My big fear with new acro pilots is the
inverted accelerated stall. A 140 knot loop in an Arrow or Mooney is going
to get slow on top. Probably very close to stall speed. The way to keep the
speed higher at the top of the loop is with a fairly aggressive pull at the
beginning of the loop - say 3.5 g's, easing off as airspeed slows. Trying to
use the elevator to tighten the loop at the top is likely to result in a
stall, and possible inverted spin.

For what it is worth, I often float over the top of a loop at 60 knots,
which is about 10 knots above stall speed. At that point, the elevator is
more or less neutral, and the airplane is performing a -2g arc. One of the
g's comes from aerodynamic lift and the other comes from gravity... That's
only a .5 G different arc than the beginning of the loop, which was a 2.5 g
arc: 3.5 aerodynamic g's in the "up" direction minus 1 g from gravity...

KB


I would agree with this as well. Pulling in tight at the apex of a loop
can easily result in a positive g snap roll, as the angle of attack is
increasing through the vertical line. Add to this that as the lift
vector passes below the horizon through the apex an additional positive
g is available, you can easily pull into a snap this way. The preferred
method would indeed be a brisk pull into the maneuver keeping the g down
so as to avoid a high induced drag index, then easing off the g past the
pure vertical line.
As for the inverted spin; it's possible if things get away from you at
the apex, but with the stall being produced by tighter positive g
instead of a push into a negative side snap, the result would most
likely be an erect spin entry if you botched the snap recovery.
Dudley Henriques

"Kyle Boatright" wrote in message
. ..

For what it is worth, I often float over the top of a loop at 60 knots,
which is about 10 knots above stall speed. At that point, the elevator is
more or less neutral, and the airplane is performing a -2g arc. One of the
g's comes from aerodynamic lift and the other comes from gravity...
That's only a .5 G different arc than the beginning of the loop, which was
a 2.5 g arc: 3.5 aerodynamic g's in the "up" direction minus 1 g from
gravity...

KB

With respect, I am a little confused as to what you are saying here.

Please clarify what you mean by a -2g arc?

IIRC, I normally see 0g to -.5g when 'floating' over the top of a loop and
with this low g loading the aircraft will have a very much reduced stall
speed.

I see no reason to add (or subtract) extra gravity to the g meter reading
when calculating load or estimating resulting stall speed.

I do not mean to be argumentative here, but I seem to be missing something.
Are you talking about the resultant radius of the arc?

Happy landings,

"Private" wrote in message
news:C7Cii.84525$NV3.39360@pd7urf2no...

"Kyle Boatright" wrote in message
. ..

For what it is worth, I often float over the top of a loop at 60 knots,
which is about 10 knots above stall speed. At that point, the elevator
is more or less neutral, and the airplane is performing a -2g arc. One of
the g's comes from aerodynamic lift and the other comes from gravity...
That's only a .5 G different arc than the beginning of the loop, which
was a 2.5 g arc: 3.5 aerodynamic g's in the "up" direction minus 1 g from
gravity...

KB

With respect, I am a little confused as to what you are saying here.

Please clarify what you mean by a -2g arc?

When the airplane is inverted and the G meter reads 1, the airplane is
accelerating downward at 2 G's. I used the (-) sign to try and convey the
direction of acceleration relative to the starting point of the loop.


IIRC, I normally see 0g to -.5g when 'floating' over the top of a loop and
with this low g loading the aircraft will have a very much reduced stall
speed.

No doubt about that.


I see no reason to add (or subtract) extra gravity to the g meter reading
when calculating load or estimating resulting stall speed.

And you're right about that too - stall speed and the G meter are directly
related, but a loop's arc is also influenced by gravity.


I do not mean to be argumentative here, but I seem to be missing
something. Are you talking about the resultant radius of the arc?

Yep. When you're upside down pulling 1 G towards the center of the loop,
mother nature adds another G due to gravity and you perform a 2 G arc in the
downward direction...


Happy landings,

More like bouncy ones recently, but that's another story. ;-)

KB

On Sat, 30 Jun 2007 00:38:38 -0000, wrote:

when you did it, did you wait until manovering speed before pulling
all the way back? I'd worry, in the Mooney, if the pilot in command
(he loves being called that) pulled back to the stops at cruise. If
you kept your wits about you, I'd guess firm back until I think 130
knots...

Pull back too abruptly and (aside from the possibility of an
accelerated stall) you'll lose more energy, since induced drag goes up
with the square of lift, which follows AOA. The best is to find just
the right balance between getting it up and over fast enough to carry
some momentum all the way to the top, and creating enough drag to kill
that momentum.

, then to the aft limit in that airplane, would probably only
break a gyro or two, and not the backbone of the airplane. I don't
know if its gyros are rated for more than 60 degrees back or pitch.

Usually in gyros not made to go all the way around, they'll just
tumble, and for the next half hour or so they'll show, say, a 45° bank
while you're in straight and level flight... but they settle down
eventually. A few times probably won't hurt 'em, but it's not good as
a regular practice.

-Dana
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