Canyon Turns

Robert Moore wrote:

Yep! We fought this battle for about two weeks last year.
There were two groups, one was the slow down and use flaps
with a shallow angle of bank and the other group (me) quoting
the aerodynamic textbook solution of flying at maneuver speed
and using about 75 degrees angle-of-bank.

Well, I'm almost certainly going to be at max angle of climb by the time I decide
I need to turn around, so maneuvering speed is out of the question. I'll be starting
my turn with 24 degrees of flaps at 70 mph.

George Patterson
Battle, n; A method of untying with the teeth a political knot that would
not yield to the tongue.

Before you try this you should know that the load rating for your 172 with
the flaps down is 2.0G and the load factor in a level 60deg turn is 2.0g.

Mike
MU-2


"Casey Wilson" wrote in message
...

"Brian Burger" wrote in message
ia.tc.ca...
On Thu, 11 Mar 2004, Casey Wilson wrote:

My apologies for coming in late, if this has already been mentioned.
How
about a chandelle or wing-over?
http://www.skyjackmotorsports.com/IAC24/aresti.html

Cool Aresti diagrams, but... if you're really, honestly in need of a
canyon turn, you're unlikely to have the excess airspeed you need to
pull
a wingover or chandelle off, and if you're turning away from rising
terrain you might not have the altitude needed to trade for the needed
airspeed either...

Sparky Imeson's "Mountain Flying Bible" points this out at least three
times; he's in favour of the 60-degree bank, with flaps up to full as
appropriate, and power as needed. Personally, doing these turns in a
172N
starting at ~80 KIAS, I've gotten the plane turned around inside the
long
dimension of a high school running track that was below us - that's
about
200-250ft, give or take.

Thanks for the book tip, Brian. First, about the mountain flying. All
my experience has been in the Southern Sierra Madre, south of Mt. Whitney,
generally, although I've poked the nose over a few other ranges and
ridgelines. Maybe I'm too conservative, but I don't fly "up" a canyon
blind.
I have to pretty much know what's up there before I let the ridgelines get
above the wings. Same thing going down-canyon -- I've got to know where it
opens up.
As far as the chandelle and wing-over, I was looking for opinions.
Now
you piqued my interest in horsing the club's 172S into a 60-degree-bank
turn
with full-flaps. I don't remember doing that with flaps. I've got a date
with my CFII next week. I wonder if the club has parachutes....
Just to pick a nit... the straight sections of the high school track
(presuming it is around a football field) is closer to 400 feet. Still a
darn tight turn, though.

That "mathematically correct" minimum radius turn, at the load factor limit
(3.8 g, 74.7 deg bank) at Va, is not realizeable in practice. For the Cessna
172 I once calculated you'd have (I forget the altitude and gross weight),
under those circumstances, a rate of descent of about 3400 fpm. Unless the
canyon's narrowing AND the floor's rising (relative to your flight path),
you might be allowed some descent in the few seconds of the turn, but not
THAT much!

John.

--
John T Lowry, PhD
Flight Physics
5217 Old Spicewood Springs Rd, #312
Austin, Texas 78731
(512) 231-9391

"G.R. Patterson III" wrote in message
...


Robert Moore wrote:

Yep! We fought this battle for about two weeks last year.
There were two groups, one was the slow down and use flaps
with a shallow angle of bank and the other group (me) quoting
the aerodynamic textbook solution of flying at maneuver speed
and using about 75 degrees angle-of-bank.

Well, I'm almost certainly going to be at max angle of climb by the time I
decide
I need to turn around, so maneuvering speed is out of the question. I'll
be starting
my turn with 24 degrees of flaps at 70 mph.

George Patterson
Battle, n; A method of untying with the teeth a political knot that
would
not yield to the tongue.

In article k.net,
"Mike Rapoport" wrote:

Before you try this you should know that the load rating for your 172 with
the flaps down is 2.0G and the load factor in a level 60deg turn is 2.0g.

I do believe the load limit is 3G with the flaps down.

--
Dale L. Falk

There is nothing - absolutely nothing - half so much worth doing
as simply messing around with airplanes.

http://home.gci.net/~sncdfalk/flying.html

Ary your sure? From memory, the requrement is 2.0G (from a Barry Schieff
book). In my flight manual (not a 172) the limit is listed as 2.0G.

Mike
MU-2


"Dale" wrote in message
...
In article k.net,
"Mike Rapoport" wrote:

Before you try this you should know that the load rating for your 172
with
the flaps down is 2.0G and the load factor in a level 60deg turn is
2.0g.

I do believe the load limit is 3G with the flaps down.

--
Dale L. Falk

There is nothing - absolutely nothing - half so much worth doing
as simply messing around with airplanes.

http://home.gci.net/~sncdfalk/flying.html

In article k.net,
"Mike Rapoport" wrote:

Ary your sure? From memory, the requrement is 2.0G (from a Barry Schieff
book). In my flight manual (not a 172) the limit is listed as 2.0G.

Mike
MU-2

Yeah, my info manual for the 172P shows 3g with flaps down..pretty sure
it's the same for the 172S

--
Dale L. Falk

There is nothing - absolutely nothing - half so much worth doing
as simply messing around with airplanes.

http://home.gci.net/~sncdfalk/flying.html

When you NEED a canyon turn, you usually are already at slow airspeed,
due to the fact that you have been trying to climb (and can't outclimb
the terrain, so you want to turn around). I teach using best angle of
climb (Vx), go over to one side of the canyon, and make only as steep
a turn as necessary to turn before you come to the other side of the
canyon.

Use of flaps, in my opinion, unecesarily complicates things. But it
can be done with or without flaps. Like Mike R pointed out, max wing
loading goes down with the flaps down, and mountains do have
turbulence, so lots of turbulence would suggest not using flaps.

You can practice this by doing the turns "above" the canyon, and when
you get proficient, drop down "into" the canyon. Use the steepest bank
angle you dare. It is suprising how small a canyon you can be in, and
still be able to turn around. You may want to get some instruction in
"steep turn stalls".

If you want true, scary, thrilling and dangerous mountain flying, the
wilderness airstrips in Idaho await you. There are primitive airports
in the bottom of some BIG canyons and you can pretty much forget about
staying over an emergency putdown area, they don't exist. Don't try it
on a hot summer afternoon, morning and after 6 pm are best. Get some
local instruction, and you will be flying patterns down in the bottom
of 4000' deep canyons landing on bumpy, short grass fields. Yikes!
Takeoffs are just as exciting.

OK I guess that the requirment is a *minimium* of 2.0G and some airplanes
are higher.

Mike
MU-2

"Dale" wrote in message
...
In article k.net,
"Mike Rapoport" wrote:

Ary your sure? From memory, the requrement is 2.0G (from a Barry
Schieff
book). In my flight manual (not a 172) the limit is listed as 2.0G.

Mike
MU-2

Yeah, my info manual for the 172P shows 3g with flaps down..pretty sure
it's the same for the 172S

--
Dale L. Falk

There is nothing - absolutely nothing - half so much worth doing
as simply messing around with airplanes.

http://home.gci.net/~sncdfalk/flying.html

"Mike Rapoport" wrote in message
hlink.net...
Before you try this you should know that the load rating for your 172 with
the flaps down is 2.0G and the load factor in a level 60deg turn is 2.0g.


What's a "level 60 degree turn"?

This is based on my experience flying a small, single engine, GA plane
around Colorado and Idaho.

From my experience, you usually wont be at manuevering speed for a
canyon turnaround, because you are trying to climb. You can't climb
fast enough to outclimb the terrain. You are trying climb out
somewhere around Vx to Vy.

I suppose it all depends on what you are doing. The times when I have
NEEDED a small radius turn I was in a narrow canyon, flying a pattern
to an unimproved strip. In another case, I went up a canyon that ended
at a mountain, not at the airport. (I went up a dead end canyon,
mistakingly thinking there was an airport there.) It was hot, bumpy, I
was heavy, and I was slow.

I suppose if you are flying high speed manuevers in canyons and want
to turn around, then turning at Va might be an option. But that is not
how most of us fly in the mountains. Most of us are either climbing
out of an airport, and can't outclimb the terrain, or are headed up a
canyon, it's not working out due to steep terrain and downdrafts, so
we have to turn around. We are flying at speeds closer to Vy and Vx,
not at Va. If I could get Va, I'd pull up until at Vx and might not
need to turn around.

Most small planes will barely climb at Va. My Husky has a Va of 94. At
gross weight on a hot day, I would not be climbing much at that speed,
maybe 50-100 fpm. And a Husky climbs well (but not at Va it doesn't).
The Cessnas I have flown are similar (though most don't climb as well
as my Husky).

If you are talking about flying fighter jets in the mountains, zooming
around the canyons, you have LOTS of power, then I would suspect it is
different. Get enough power, your climb problems are over, just go
straight up!

Robert Moore wrote in message .7...
"Marc Lattoni" wrote

Today we did canyon turns, not at 30, not at 45 but more than 45
degrees. Sort of standing the airplane on its wingtip as we turn.

Yep! We fought this battle for about two weeks last year.
There were two groups, one was the slow down and use flaps
with a shallow angle of bank and the other group (me) quoting
the aerodynamic textbook solution of flying at maneuver speed
and using about 75 degrees angle-of-bank.

Quoting from "Aerodynamics For Naval Aviators":

"The aerodynamic limit of turn radius requires that increased
velocity be utilized to produce increasing load factors and
greater angles of bank"

"The maneuver speed is the minimum speed necessary to develop
aerodynamically the limit load factor and it produces the
minimum turn radius within aerodynamic and structural limits."

Bob Moore