Flying a pattern with only trim?

M

MultiMediaWill

Pre-takeoff checklist
Joined
Oct 29, 2012
Messages
246
Display Name
Display name:
Will
Is it possible to fly a pattern in a 172 only touching the yoke to turn and using the trim only for elevator?
 
Last edited:
Nope. Can't flare adequately that way. Not enough nose-up trim. In many aircraft, you'll be close to full nose up trim on final with good approach speed and full flaps. In a Cessna or Piper even without flaps, you can't trim slower than best glide.

And crosswind landings are gonna be real fun with no aileron.
 
If a control failure made that necessary, yes, you could get it safely on the ground. With skill, luck, maybe a bit of practice. And, of course, you can also steer the Cessna with the doors.
 
PBristolJr said:
Yes, you can do it without touching the yoke at all, just use the rudder to turn.
Click to expand...

You certainly can do it with a C150. My CFI demonstrated such a pattern one evening - from a standing start to the flare - but he did use the yoke for the flare. It was his way of showing this 17YO that his death grip was unnecessary. I soloed soon after.
 
MAKG1 said:
Nope. Can't flare adequately that way. Not enough nose-up trim. In many aircraft, you'll be close to full nose up trim on final with good approach speed and full flaps. In a Cessna or Piper even without flaps, you can't trim slower than best glide.

And crosswind landings are gonna be real fun with no aileron.
Click to expand...

Wrong, and wrong. In fact in my training I was required to do it with trim and runner only before getting signed off.

And there is no need to flare. Just keep the nose wheel from hitting first at an appropriate airspeed. In my PA28 and my PA24 I can trim to way way way below best glide, and in the PA24, I actually trim to flare - though I don't actually flare. But I have zero back pressure on the yoke on final, and I still have about 25% more nose up trim I can use.
 
As Captain Tupolev's chief engineer told him about going to 105% on the reactor in The Hunt for Red October, "Possible, but not recommended." As noted above, the biggest risk is pranging the nosewheel on touchdown.
 
MultiMediaWill said:
Is it possible to fly a pattern in a 172 only touching the yoke to turn and using the trim only for elevator?
Click to expand...

I flew with a wise, old CFI who has roughly 6500 hours in a 172 and one day with me in the left seat he showed me a lap around the pattern without touching the yoke at all. He used just power and rudder and touched the trim wheel twice. He's the same guy who had me do a pattern with a towel covering the entire panel.
 
Last edited:
Can someone explain how the rudder would effectively turn you? Also wouldn't you be asking for a spin on base to final using rudder only?
 
MultiMediaWill said:
Can someone explain how the rudder would effectively turn you? Also wouldn't you be asking for a spin on base to final using rudder only?
Click to expand...

It moves the nose of the plane. Rudders turn boats don't they? I've never seen ailerons (waterons?) on a boat, and those turn. The thrust moves you the way the nose points. Second question: Only if you're an idiot.
 
Get out the weight and balance and figure out how much weigh you need to add to the baggage to get the CG to the aft limit. Then you'll have enough elevator trim.
 
MultiMediaWill said:
Can someone explain how the rudder would effectively turn you? Also wouldn't you be asking for a spin on base to final using rudder only?
Click to expand...

Simply put, the rudder pushes one wing forward into the airstream (relative wind), which causes the other to be partially blocked by the fuselage. More airflow equal more lift, less airflow equal less lift, ergo bank. Yes, you want to take it easy on the rudder.
 
Ron Levy said:
As noted above, the biggest risk is pranging the nosewheel on touchdown.
Click to expand...

I think a no-flaps landing would go a long way in preventing this. Should permit you to achieve a higher deck angle on touchdown with your limited elevator authority.
 
Would this be a good thing to practice in case of full control failure?
 
MultiMediaWill said:
Would this be a good thing to practice in case of full control failure?
Click to expand...



You're more likely to lose engine control due the chicken **** mixture control breaking and horribly old/worn throttle cables that are ignored.
 
The other end of the mixture control is a single solid core wire attached the carburetor mixture arm via a bolt with a hole drilled into it and a nut that jams the wire from coming out of the bolt. That wire vibrates against the side of the steel wound sheath which wears a weak spot into the wire. Eventually they will break.
 
MultiMediaWill said:
Would this be a good thing to practice in case of full control failure?
Click to expand...

Very unlikely, but it's good to practice things like this so you can really see the relationship between pitch, power, and airspeed especially during climbs and descents.
 
I know the OP mentioned 172's but Red Stewart used to fly over the airport, throw both sticks out of his J-3 and come back to make a greaser of a landing.
 
EdFred said:
Wrong, and wrong. In fact in my training I was required to do it with trim and runner only before getting signed off.

And there is no need to flare. Just keep the nose wheel from hitting first at an appropriate airspeed. In my PA28 and my PA24 I can trim to way way way below best glide, and in the PA24, I actually trim to flare - though I don't actually flare. But I have zero back pressure on the yoke on final, and I still have about 25% more nose up trim I can use.
Click to expand...

Umm, in that PA28, when you do engine-out practice, where is the trim?

And are you loading the thing to full aft CG, perhaps? Not a common configuration for a student and instructor.

I've never flown a PA24, so I can't comment on that. But in a PA28 (tried in Warrior and Archer) with nothing in back, the trim is all the way up at best glide, hands off, power off, with no flaps. Same deal in all the Cessnas I've tried (several 172s, 177, 182).
 
DesertNomad said:
I flew with a wise, old CFI who has roughly 6500 hours in a 172 and one day with me in the left seat he showed me a lap around the pattern without touching the yoke at all. He used just power and rudder and touched the trim wheel twice. He's the same guy who had me do a pattern with a towel covering the entire panel.
Click to expand...


Our instructors were separated at birth. :)
 
alfadog said:
Simply put, the rudder pushes one wing forward into the airstream (relative wind), which causes the other to be partially blocked by the fuselage. More airflow equal more lift, less airflow equal less lift, ergo bank. Yes, you want to take it easy on the rudder.
Click to expand...
Not correct

EdFred said:
It moves the nose of the plane. Rudders turn boats don't they? I've never seen ailerons (waterons?) on a boat, and those turn. The thrust moves you the way the nose points. Second question: Only if you're an idiot.
Click to expand...
So wrong one wonders if sarcasm is involved.

All of these airplanes have wings with dihedral. When you use rudder to yaw these planes, dihedral causes one wing to experience a higher angle of attack than the other which causes a roll in the direction of the yaw. Then as in any turn, lift vector of the rolled wing causes a turn in the flight path.

Works on gliders as well as airplanes so the thrust idea is nonsense.

Think about the fuselage blocking relative to low wing, high wing or even a parasol wing and the impact of any 'blocking' effect becomes suspect. I once read someone attribute such an effect to some mid-wing fighter jet but that immediately suggests wing sweep might be involved which further complicates such an example.

Many thousands of model aircraft, planes and gliders, have been turned solely with a controllable rudder. Wing dihedral is the critical element in such designs.

So for the bonus round, describe how a model airplane with only rudder control can be looped. :idea:
 
MultiMediaWill said:
Can someone explain how the rudder would effectively turn you?
Click to expand...
Application of rudder yaws the plane, advancing the outside wing and retarding the inside wing. That creates a difference in airspeed between the two wings, with more speed on the outside wing. Since the two wings are at the same angle of attach, the extra speed on the outside wing creates more lift on that wing, rolling the plane around its longitudinal axis.

Also wouldn't you be asking for a spin on base to final using rudder only?
Click to expand...
Not as much as using ailerons only. While there is a bit more drag on the outboard wing due to the greater airspeed, the fact that the rudder is applied in the direction of the turn pretty much coordinates the turn. While there is still a bit of a skid, it's not nearly as out-of-coordination as using aileron with no rudder at all. This is pretty easy to test yourself in flight by first rudder-rolling with ailerons neutral, and then aileron-rolling with the rudder centered, and comparing how far out of center the ball is in each case. If you're concerned about a spin, just keep your speed up near cruise when you try this, since you can't spin without stalling first.
 
MultiMediaWill said:
Would this be a good thing to practice in case of full control failure?
Click to expand...
Certainly, but be spring-loaded to the grab-the-yoke position, especially as you get close to the ground lest you plant the nosewheel and damage the aircraft. It might take a few tries ending in a hands-on-yoke go-around before you get it to the point where you can land it gently enough not to hurt anything this way.
 
It's a good exercise anyway. Controlling roll with the rudder is how you recover from a dipped wing in a stall. It is not good to try this with aileron. It's also convenient for looking stuff up when you get no response on a frequency or when you have to refold a chart or do something else with both hands (call to nature? not something I do while airborne, but some people do).

There is a transient when you try to turn that way. The aircraft lags the roll a little, so you'll be a bit out of coordination, but then it will correct to pretty close.
 
Ron Levy said:
Application of rudder yaws the plane, advancing the outside wing and retarding the inside wing. That creates a difference in airspeed between the two wings, with more speed on the outside wing. Since the two wings are at the same angle of attach, the extra speed on the outside wing creates more lift on that wing, rolling the plane around its longitudinal axis.
Click to expand...
There are a few ways to demonstrate this does not have a significant effect. Many RC planes are designed with zero dihedral so that a rudder induced yaw has little or no roll effect. There are full scale airplanes designed simularly.

However, it may be an effective way to teach the way a rudder-only turn can be performed with a trainer. The logic works consistent with the way most trainers react.
 
Bill Watson said:
There are a few ways to demonstrate this does not have a significant effect. Many RC planes are designed with zero dihedral so that a rudder induced yaw has little or no roll effect. There are full scale airplanes designed simularly.
Click to expand...

It absolutely does have effect. Yawing a plane with will momentarily make one wing go faster than the other, which means more lift on one wing creating a roll.

Ive flown many airplanes (not trainers) with no dihedral and have been able to turn / create a roll easily with only the rudder.

This explanation was right on:

Ron Levy said:
Application of rudder yaws the plane, advancing the outside wing and retarding the inside wing. That creates a difference in airspeed between the two wings, with more speed on the outside wing. Since the two wings are at the same angle of attach, the extra speed on the outside wing creates more lift on that wing, rolling the plane around its longitudinal axis.
Click to expand...
 
I had a weed hopper ultralight back in the day. It had no ailerons, just rudder and elevators. It flew very well.
 
You must log in or register to reply here.
Back
Top