Va and negative g's & fun non-acrobatic maneuvers

"darryl" wrote in message
m...
"Anyone" wrote in message
...
Get acro instruction in a Pitts, Decathlon, etc. Doing what you want in
a
172, while maybe possible, is dangerous and quite honestly, a little
sad.
It's like trying to race a Geo Metro. I've got nothing against the 172,
it's just not well suited for what you want. The FBO I rent from rents
a
Decathlon for $10/hr more than their SP's. I'm sure you can find one
for
about what you pay for the 172.

BTW - your comment "stall horn, give it good nudge forward on the
stick"...
a 172SP doesn't have a stick, it has a wheel. Sticks are for acro's, a
172
isn't an acro.




"Koopas Ly" wrote in message
om...
Me again,

Va seems to be only intended to protect against excessive positive
load factors. What about negative g's?

Can I find a Va for negative design load factors (-1.52 g) for the
C172SP anywhere?

Reason I am asking is that I want to try the "floating pencil" trick
next time I fly but I don't want to shove the stick fully forward for
fear of breaking something. I am not looking to induce negative g's,
only zero g's and zero lift. Any pointers on entry speed and power
settings? Is it easier to perform if you induce a gradual +1 g steep
climb similar to a departure stall maneuver, then upon hearing the
stall horn, give it good nudge forward on the stick? I've heard that
your airspeed may indicate well below stall, but again, your stall
speed does approach zero as your load factor goes to zero.

Likewise, would you prefer to pull 2 positive g's in a pull-up
maneuver or a, say, 60 deg. bank? Frankly, I am not too familiar with
the former so I might do something undesirable. Aside from my stall
speed going up to something like 68 kts. clean (Va ~ 100 kts), you'd
see your airspeed quickly dwindling while pulling up. I think it'd be
fruitless to add in power since heck, you're not maintaining altitude
and besides, you probably don't have any excess power anyway to do
that. Neither am I familiar with the mechanics of loops so it'd be
wiser to leave that alone. Perhaps the 60 deg. bank is more
reasonable to have some fun. Would you try to hold altitude with
backpressure and power or just leave the plane to dive and speed up in
the spiral, with a recovery before Vne? I think the maneuver would be
more innocuous with power-off a-la-emergency-descent style. Again,
I've never done a 60 deg. bank...so I should probably leave that alone
too until I try it with a passenger...oops..i mean CFI.

Seriously, if someone has something to suggest that's fun and safe,
within normal operating range and category, please suggest. It's a
buddy's bday soon and he wants to go up. Again, I am not looking for
doing anything aerobatic.

Alright, I can see the flames and derision coming from the mainland

May you have a peaceful week with no stress,
Alex

Aside from the 172 not being stressed for fooling around like this it
is a pain in the backside. Not quite like a truck, more like going
to a sports car race in a SUV. A good plane to get aero in would be
a 150 aerobat (did they make a 152 aerobat?) I'm assuming you've
been flying mostly Cessnas. The feel and controls will be familiar
and you will have to finesses it to get clean manuvers.
You can avoid the trouble of "taming a taildragger" and still learn
some good stuff and have some fun.
You can go for the Serious Iron later if you get addicted.
Darryl
46 Taylorcraft

You can avoid the trouble of "taming a taildragger"
It'll make him a better pilot if he learns. If he can't control the plane
well enough to land a taildragger he shouldn't be doing acro. Trikes are
for kids and wheels are for cars. Taildragger with a stick is the only way
to go.

'46 Taylorcraft - nice, very nice.

"darryl" wrote in message
m...
Aside from the 172 not being stressed for fooling around like this it
is a pain in the backside.

A 60 degree turn and a 0g bunt?

Paul

Can I find a Va for negative design load factors (-1.52 g) for the
C172SP anywhere?

I think I calculated Vs for a negative AOA to be about 60 knots in a
172. That would put Va at about 74 knots.

Like many speeds in an airlane, maneuvering speed, Va, is related to
the wings-level, stall speed Vso by the square root of the g-load.
There is a positive side and a negative side.

For example, for Normal category, positive g operations, where the
design limit is +3.8-g, Va = 1.95 x Vso. (Note: this relationship
applies to CAS, so you must use the airspeed calibration figures in
the POH to move back and forth between IAS and CAS to find the actual
number you should see on the airspeed indicator).

If you know the wings-level, -1.0-g stall speed of the airplane (which
will in all likelihood be greater than the upright Vso), then you can
find the inverted Va, which will be 1.23 x the inverted Vso. Of
course, the inverted operating envelope is quite small.

As for your "trick" -- sure, it's something that can be done from a
steep climb followed by a pushover as the speed decays. But EVERYTHING
that is not bolted down in the airplane will float, not just the
pencil -- flashlights, flight bags, dirt, towbars, etc. And if the g
is too light, the engine may balk...

I'd recommend trying it with an instructor in an aerobatic airplane
instead.

Rich
http://www.richstowell.com


(Koopas Ly) wrote in message . com...
Me again,

Va seems to be only intended to protect against excessive positive
load factors. What about negative g's?

Can I find a Va for negative design load factors (-1.52 g) for the
C172SP anywhere?

Reason I am asking is that I want to try the "floating pencil" trick
next time I fly but I don't want to shove the stick fully forward for
fear of breaking something. I am not looking to induce negative g's,
only zero g's and zero lift. Any pointers on entry speed and power
settings? Is it easier to perform if you induce a gradual +1 g steep
climb similar to a departure stall maneuver, then upon hearing the
stall horn, give it good nudge forward on the stick? I've heard that
your airspeed may indicate well below stall, but again, your stall
speed does approach zero as your load factor goes to zero.

Likewise, would you prefer to pull 2 positive g's in a pull-up
maneuver or a, say, 60 deg. bank? Frankly, I am not too familiar with
the former so I might do something undesirable. Aside from my stall
speed going up to something like 68 kts. clean (Va ~ 100 kts), you'd
see your airspeed quickly dwindling while pulling up. I think it'd be
fruitless to add in power since heck, you're not maintaining altitude
and besides, you probably don't have any excess power anyway to do
that. Neither am I familiar with the mechanics of loops so it'd be
wiser to leave that alone. Perhaps the 60 deg. bank is more
reasonable to have some fun. Would you try to hold altitude with
backpressure and power or just leave the plane to dive and speed up in
the spiral, with a recovery before Vne? I think the maneuver would be
more innocuous with power-off a-la-emergency-descent style. Again,
I've never done a 60 deg. bank...so I should probably leave that alone
too until I try it with a passenger...oops..i mean CFI.

Seriously, if someone has something to suggest that's fun and safe,
within normal operating range and category, please suggest. It's a
buddy's bday soon and he wants to go up. Again, I am not looking for
doing anything aerobatic.

Alright, I can see the flames and derision coming from the mainland

May you have a peaceful week with no stress,
Alex

"Rich Stowell" wrote in message
om...
Like many speeds in an airlane, maneuvering speed, Va, is related to
the wings-level, stall speed Vso by the square root of the g-load.


I have a horrible premonition that we're about to rehash
the "Overweight takeoff" thread again.....

--
Dr. Tony Cox
Citrus Controls Inc.
e-mail:
http://CitrusControls.com/

(Koopas Ly) wrote in message . com...
Me again,

Va seems to be only intended to protect against excessive positive
load factors. What about negative g's?

Can I find a Va for negative design load factors (-1.52 g) for the
C172SP anywhere?

Reason I am asking is that I want to try the "floating pencil" trick
next time I fly but I don't want to shove the stick fully forward for
fear of breaking something. I am not looking to induce negative g's,
only zero g's and zero lift. Any pointers on entry speed and power
settings? Is it easier to perform if you induce a gradual +1 g steep
climb similar to a departure stall maneuver, then upon hearing the
stall horn, give it good nudge forward on the stick? I've heard that
your airspeed may indicate well below stall, but again, your stall
speed does approach zero as your load factor goes to zero.

It can be done from cruise speed. Pull up into a shallow climb,
then start pushing forward, increasing pressure until the pencil comes
off the panel. It'll feel like negative G's but isn't. The only stress
on the airplane occurs when you pull out of the shallow dive created
by the maneuver. You don't have to get the nose way up or down at all,
and it doesn't require abrupt, or anywhere near full, control inputs.
Kids love it.
MAKE SURE EVERYTHING IS TIED DOWN IN THE CABIN. Floating cargo
can depart through a window or it can come down hard on the pullout
and damage something.


Dan

In article , Dan
Thomas wrote:

MAKE SURE EVERYTHING IS TIED DOWN IN THE CABIN. Floating cargo
can depart through a window or it can come down hard on the pullout
and damage something.

And the dust and dirt from the floor will get in your eyes.

EDR wrote in message ...
In article , Dan
Thomas wrote:

MAKE SURE EVERYTHING IS TIED DOWN IN THE CABIN. Floating cargo
can depart through a window or it can come down hard on the pullout
and damage something.

And the dust and dirt from the floor will get in your eyes.


We keep our airplanes clean.

I'm wondering how this maneuver risks breaking or stalling the
airplane, as some earlier posters indicated. Done this numerous times,
and the carbureted engine didn't cough, either. It's only for a second
or two. G forces on pullout are minimal. People who level off too fast
from a climb can get the same effect. Rough air on a warm day, or a
windy day in the mountains, can be much worse. Should we avoid flying
then, too?

Dan

People flying inverted usually manage to find dirt they never knew about.

Paul

"Dan Thomas" wrote in message
om...
EDR wrote in message
...
And the dust and dirt from the floor will get in your eyes.

We keep our airplanes clean.

Paul Sengupta wrote:

People flying inverted usually manage to find dirt they never knew about.

Once they find it, they know about it, though. I hear that it seems to wind up
in the eyes.

George Patterson
Some people think they hear a call to the priesthood when what they really
hear is a tiny voice whispering "It's indoor work with no heavy lifting".