Methods for altitude changes

Thanks. I've visited that site before; the author becomes very abstract at
times, but it is useful information.

Personally, as an engineer and generally 'theoretical' guy, I enjoy
the abstraction... but I understand what you're saying.

By pitch climbing do you mean with the yoke, or with trim adjustments?

Yoke. Changing pitch attitude almost always induces phugoid
oscillations, with the yoke, those oscillations are trivial (almost
subconscious) to damp. Trim provides no such mechanism (without
grabbing the yoke anyways), so its generally a bad idea to fly with
it.

For any pitch attitude change, the general rule of thumb is pitch,
power, trim off pressure as necessary, in that order.

If I have nose-down trim applied to go fast at my low altitude, it seems I
should be able to trim slightly upwards and change altitude easily, then trim
back for level flight at the new altitude. If I already have nose-up trim
applied, this may not work, and eventually I'll have to add power.

It sounds like you're trying to fight the simulated phugoid
oscillation by using trim to make very low amplitude adjustments...
This just increases the period of the oscillations, it in no way
prevents them from occurring.

Power is a good, 'side effect free' mechanism of doing fine trimming
of your aircraft's altitude. In fact, I know instructors who advocate
only ever using the power to make the final 'lock' onto a new cruise
altitude, no matter what.

For example, the mechanism you would use to level off from a cruise
climb would be as follows:

500 feet below target altitude, push the nose forward gently to bring
airspeed up to cruise airspeed. Once you've reached cruise airspeed,
go ahead and trim to hold the attitude, but allow your power surplus
to continue pulling you up the last hundred feet or so to your target
altitude, only backing off the power the moment you reach it.

The descend-to-altitude is the same procedure, only with reduced power
instead (set up the aircraft in cruise attitude before you hit your
target altitude at a reduced descent power setting, and allow the
aircraft to settle onto target altitude before increasing power back
to cruise power)

I can see the theoretical advantages to this approach, but I would be
lying if I said I used to religiously (I still don't keep that far
ahead of the aircraft).

On Apr 7, 8:11 am, Mxsmanic wrote:
Suppose you're in your small aircraft and you want to climb from 4000 to 6000,

As with all things aviation, it depends.

Under IFR, they like you to climb quickly, at least 500 fpm. That
often requires mixture rich, maybe rpm increase, plus more manifold
pressure via throttle (unless you're already maxed out above 5000 ft).

On the other hand, if you've been yakking with a passenger and
suddenly realize you're 200 ft low, just pull the yoke.

For serious climbing, use power and rich mixture, then reduce MP,
prop, and mixture as needed at desired altitude.

"EridanMan" wrote in message
ups.com...
snip

Yoke. Changing pitch attitude almost always induces phugoid
oscillations, with the yoke, those oscillations are trivial (almost
subconscious) to damp. Trim provides no such mechanism (without
grabbing the yoke anyways), so its generally a bad idea to fly with
it.


You bring up a good point on phugoids. I have flown everything from J-3
cubs to F-4E (but no heavy time) and the difference in phugoid tendancy is
HUGE. On the Air Force jets, the trim in on the stick, so I didn't fly just
trim. I am currently flying a Taylorcraft which must have a highly damped
phugoid. I find I can fly it with only trim to make gradual changes in
altitude. In other planes, this can't be done as you mention.

Danny Deger

For any pitch attitude change, the general rule of thumb is pitch,
power, trim off pressure as necessary, in that order.

If I have nose-down trim applied to go fast at my low altitude, it seems
I
should be able to trim slightly upwards and change altitude easily, then
trim
back for level flight at the new altitude. If I already have nose-up
trim
applied, this may not work, and eventually I'll have to add power.

It sounds like you're trying to fight the simulated phugoid
oscillation by using trim to make very low amplitude adjustments...
This just increases the period of the oscillations, it in no way
prevents them from occurring.

Power is a good, 'side effect free' mechanism of doing fine trimming
of your aircraft's altitude. In fact, I know instructors who advocate
only ever using the power to make the final 'lock' onto a new cruise
altitude, no matter what.

For example, the mechanism you would use to level off from a cruise
climb would be as follows:

500 feet below target altitude, push the nose forward gently to bring
airspeed up to cruise airspeed. Once you've reached cruise airspeed,
go ahead and trim to hold the attitude, but allow your power surplus
to continue pulling you up the last hundred feet or so to your target
altitude, only backing off the power the moment you reach it.

The descend-to-altitude is the same procedure, only with reduced power
instead (set up the aircraft in cruise attitude before you hit your
target altitude at a reduced descent power setting, and allow the
aircraft to settle onto target altitude before increasing power back
to cruise power)

I can see the theoretical advantages to this approach, but I would be
lying if I said I used to religiously (I still don't keep that far
ahead of the aircraft).

EridanMan writes:

It sounds like you're trying to fight the simulated phugoid
oscillation by using trim to make very low amplitude adjustments...

I try it sometimes, on the theory that the more precise changes possible with
tiny bits of trim might prevent me from overcorrecting, whereas gross movement
of the yoke seems more likely to take me past the correct adjustment.

This just increases the period of the oscillations, it in no way
prevents them from occurring.

If the period becomes long enough, the oscillation is gone for all effective
purposes.

Sometimes I cheat and turn on the autopilot to trim out the oscillations. I
also sometimes use the autopilot to trim and then adjust power until the AP is
giving me neutral trim (which gives me more trim authority and hopefully
reduces drag, although it also means that I can't necessarily fly at high
speeds).

Power is a good, 'side effect free' mechanism of doing fine trimming
of your aircraft's altitude. In fact, I know instructors who advocate
only ever using the power to make the final 'lock' onto a new cruise
altitude, no matter what.

See above. I've also tried setting neutral trim (in steps or in one
adjustment) and then using power to find a setting that will keep me at the
desired altitude with that trim. It seems to be more difficult but the
aircraft is very stable once in that configuration.

500 feet below target altitude, push the nose forward gently to bring
airspeed up to cruise airspeed. Once you've reached cruise airspeed,
go ahead and trim to hold the attitude, but allow your power surplus
to continue pulling you up the last hundred feet or so to your target
altitude, only backing off the power the moment you reach it.

That sounds like a plan. I don't know if I've tried it (I may have done so
unconsciously, but I'll have to try it explicitly).

I can see the theoretical advantages to this approach, but I would be
lying if I said I used to religiously (I still don't keep that far
ahead of the aircraft).

I suppose it depends to some extent on how much time you have on your hands.
If you're going to be in cruise for a long while, it's more practical than if
you know you're going to have to change altitude regularly (as over terrain of
widely varying elevations at lower altitudes).

--
Transpose mxsmanic and gmail to reach me by e-mail.

Paul kgyy writes:

For serious climbing, use power and rich mixture, then reduce MP,
prop, and mixture as needed at desired altitude.

_Always_ rich for a climb? At altitudes above a few thousand feet MSL, it
seems that a rich mixture just slows me down.

--
Transpose mxsmanic and gmail to reach me by e-mail.

"Mxsmanic" wrote in message
...
Paul kgyy writes:

For serious climbing, use power and rich mixture, then reduce MP,
prop, and mixture as needed at desired altitude.

_Always_ rich for a climb? At altitudes above a few thousand feet MSL, it
seems that a rich mixture just slows me down.


When was the last time you cleaned the plugs in your DESK?

In rec.aviation.piloting Mxsmanic wrote:
EridanMan writes:

It sounds like you're trying to fight the simulated phugoid
oscillation by using trim to make very low amplitude adjustments...

I try it sometimes, on the theory that the more precise changes possible with
tiny bits of trim might prevent me from overcorrecting, whereas gross movement
of the yoke seems more likely to take me past the correct adjustment.

Pilots in real airplanes learn to fly using the yoke to control the
airplane and the trim to remove yoke pressure.

Since simulators that simulate yoke pressure cost as much as real
airplanes, you will never be able to do it.

This just increases the period of the oscillations, it in no way
prevents them from occurring.

If the period becomes long enough, the oscillation is gone for all effective
purposes.

Sometimes I cheat and turn on the autopilot to trim out the oscillations. I
also sometimes use the autopilot to trim and then adjust power until the AP is
giving me neutral trim (which gives me more trim authority and hopefully
reduces drag, although it also means that I can't necessarily fly at high
speeds).

Power is a good, 'side effect free' mechanism of doing fine trimming
of your aircraft's altitude. In fact, I know instructors who advocate
only ever using the power to make the final 'lock' onto a new cruise
altitude, no matter what.

See above. I've also tried setting neutral trim (in steps or in one
adjustment) and then using power to find a setting that will keep me at the
desired altitude with that trim. It seems to be more difficult but the
aircraft is very stable once in that configuration.

In real aircraft you set the power to an appropriate value, adjust the
attitude for level flight, and trim off the pressure.

500 feet below target altitude, push the nose forward gently to bring
airspeed up to cruise airspeed. Once you've reached cruise airspeed,
go ahead and trim to hold the attitude, but allow your power surplus
to continue pulling you up the last hundred feet or so to your target
altitude, only backing off the power the moment you reach it.

That sounds like a plan. I don't know if I've tried it (I may have done so
unconsciously, but I'll have to try it explicitly).

I can see the theoretical advantages to this approach, but I would be
lying if I said I used to religiously (I still don't keep that far
ahead of the aircraft).

I suppose it depends to some extent on how much time you have on your hands.
If you're going to be in cruise for a long while, it's more practical than if
you know you're going to have to change altitude regularly (as over terrain of
widely varying elevations at lower altitudes).

In a real airplane that burns real gas that costs real money, you climb
to a cruise altitude that allows for all the terrain and stay there.

--
Jim Pennino

Remove .spam.sux to reply.

In rec.aviation.piloting Mxsmanic wrote:
Paul kgyy writes:

For serious climbing, use power and rich mixture, then reduce MP,
prop, and mixture as needed at desired altitude.

_Always_ rich for a climb? At altitudes above a few thousand feet MSL, it
seems that a rich mixture just slows me down.

In a real airplane with a real engine that generates real heat and
costs real money to overhaul there are conciderations beyond how
fast you go.

--
Jim Pennino

Remove .spam.sux to reply.

In a real airplane that burns real gas that costs real money, you climb
to a cruise altitude that allows for all the terrain and stay there.

Hell, I dunno, I think in a real plane that burns real gas, his
inadvertent decision to toddle along at Vy would actually give him
pretty good gas milage

But yeah, I missed that bit.

writes:

Pilots in real airplanes learn to fly using the yoke to control the
airplane and the trim to remove yoke pressure.

That is only one of several ways to trim.

Since simulators that simulate yoke pressure cost as much as real
airplanes, you will never be able to do it.

See above. It's important to be flexible.

In a real airplane that burns real gas that costs real money, you climb
to a cruise altitude that allows for all the terrain and stay there.

That does not seem to be the consensus here.

--
Transpose mxsmanic and gmail to reach me by e-mail.