More flight test questions...

[123Fly]

Hi,
My recruiter said to know what happens to the controls of the plane when the engine stalls, any ideas? Also, what are the different types of fuselage? What my recruiter is telling me to study closely correlates with what seems to be test 3. Are the tests extremely different, or is it likely I am going to be taking test 3 if he has said things such as, "know how many Apollo missions their have been, know about wingtip vortices, hypoxia, ..."
I appreciate any help.

 

[Fly Navy]

IF the engine stalls? Well on a typical light piston aircraft, nothing. They still work. They're not dependent on engine power. Now, what happens to the controls if the wing stalls is another story.

 

[123Fly]

What's the other story? Maybe I got it wrong.
Thanks.

 

[Fly Navy]

What's the other story? Maybe I got it wrong.
Thanks.

Depends on the wing and how they engineer it. The idea is to have the wing root stall first, so that you still have aileron authority into the stall. If the wing tip stalls first, you loose aileron control. A lot of factors that I doubt are on the ASTB... but I could be wrong...

 

[HAL Pilot]

When a plane stalls, it is because the wing has lost the lift required to keep it flying. If the wing area around the controls stalls, the controls (i.e. the ailerons) lose their effectiveness. This lose of effectiveness is because the air flow accross the controls is lost. To prevent this from happening, wings are designed so the stall first at the base by the fuselage. As the plane goes deeper into the stall (i.e. wing loses more lift), the area of the wing that is stalled moves outwards towards the tips. If the stalled area moves all the way to the tips, you lose aileron effectiveness and can not control the roll of the aircraft.

The pitch of the aircraft is controlled by the elevator of the horizontial stabilizer (the smaller rear wing at the tail of the aircraft). It too reliies on airflow accross it to be effective. The airflow accross the elevator gets distrubed as the plane enters a stall and detaches from the surface of the elevator. In essence, the elevator justs flaps in the wind and it has no effect on the pitch of the aircraft. Luckily (or rather through good design), this too happens latter on in the progression of the stall and you have to be really deep into the stall to lose elevator effectiveness.

To get a wing to stall, you have to exceed it's maximum angle of attack. The angle of attack is the angle the wing makes with the direction of the airflow hitting it's forward or leading edge.

Most planes have a stall indicator of some type (horn, light or stick shaker) plus the first signs of approaching a stall is usually readily apparent to a trained pilot from the way the aircraft buffets. To stop a stall from happening or recover from the stall you simply lower the nose and add power. This decreases the angle of attack and increases the airflow accross the wing - providing more lift.

This is a very basic explanation for the non-pilot.

 

[Fly Navy]

Thanks HAL Pilot for tackling the long version.

And you don't need to add power. You might not be able to. Only requirement is to break that AOA

 

[123Fly]

Oh, the controls i.e. the ailerons, that makes sense. Thanks.

 

[HAL Pilot]

And you don't need to add power. You might not be able to. Only requirement is to break that AOA

Yaeh I know, but most flight training (at least civilian) says to add power. We teach that even if the power is already at max as a memory/procedures thing. This is true even in the 121 world where instead of lowering the nose below the horizon, we lower to the horizon (or just above) and go to takeoff power to fly out of the stall. Where light aircraft pilots are taught to recover with minimal altitude loss, 121 (and civilian bizjet) pilots are taught to recover with no altitude loss.

I realize a manuevering military aircraft may already be at max power when exceeding max AOA, or may not want to add power because of the manuever/engagement he's in.

Like I said - I geared my answer towards the novice or non-pilot.

 

[Fly Navy]

Like I said - I geared my answer towards the novice or non-pilot.

Well, even for a novice pilot... what if your engine is dead? Can't add power. Or, if you're in a bingo glide... can't add power ... well you can, but might not want to. That's what I was getting at.

 

[Lonestar155]

In a stall aren't you suppose to drop the nose of the aircraft first and then apply power? In a prop plane esspecially if you add full power you are creating the four left turning tendancies of an aircraft.

 

[squeeze]

In a stall aren't you suppose to drop the nose of the aircraft first and then apply power? In a prop plane esspecially if you add full power you are creating the four left turning tendancies of an aircraft.

stall recovery techniques vary
but usually require breaking the stalled AOA and adding power. to correct for the p-factor business, thats why prop planes have a lot of rudder authority.

 

[nugget81]

Check out the website below and read Chapter 4 for stalls. There will be a test on Friday...

http://www.faa.gov/library/manuals/aircraft/airplane_handbook/

BTW, What exactly is the "maximum angle of attack"? I thought it was called the "critical angle of attack"....

 

[mules83]

BTW, What exactly is the "maximum angle of attack"? I thought it was called the "critical angle of attack"....

It is the same thing to my knowledge, just people have different ways to say it. The correct term is "critical angle of attack"

 

[HAL Pilot]

It is the same thing to my knowledge, just people have different ways to say it. The correct term is "critical angle of attack"

If I said the wing exceeded its critical angle of attack, the average non-pilot layman would probably be confused. So I said maximum to make it clearer for the layman.

If I was posting for a pilot or SNA, I would have used many different terms and explainations.

In a stall aren't you suppose to drop the nose of the aircraft first and then apply power? In a prop plane esspecially if you add full power you are creating the four left turning tendancies of an aircraft.

If I was teaching a civilian to fly a Cessna, for stall recovery I would teach:
1. Lower the nose to or below the horizon
2. Apply maximum power (throttle and mixture both full forward simultaneously)
3. Level the wings
4. Use rudder as necessary to keep the ball centered
I would also teach him to do these things in this order, but as near as possible to do all simultaneously.

The only worry I would have concerning left turning tendencies is for the stall to be uncoordinated and to develop into a spin. However, once you lower the nose, you've broken the stall. Even though you may be descending and speeding up, you will not enter a spin if you've broken the stall. So worst case from the left turning tendencies as you add power is uncoordinated flight - not a killer. Further, by the time you get into an aircraft with either an engine big enough to have significant tendencies or a multi-engine where a lost of an engine can exaggerate these tendencies, you will have your stall recoveries down and this won't be a problem for you.

Well, even for a novice pilot... what if your engine is dead? Can't add power. Or, if you're in a bingo glide... can't add power ... well you can, but might not want to. That's what I was getting at.

I would teach a novice pilot (per the FAA guidlines) the above 4 steps. It is a procedure/memory thing. If the engine is dead pushing the power forward won't help, but it won't hurt either and it keeps them following a procedure. And, many times in light piston aircraft, this is actually enough to restart a dead engine - especially if the thing that caused the failure was a fuel problem (carb, mixture, etc.). Further, novice pilots don't have bingo profiles. They know max glide speed/configuration for the aircraft they are training in, but at their level breaking the stall is more important than trying to break the stall while maintaining a profile. Per the FAA, teach a private student to handle the most threatening problem first, than they can resume whatever else is going on (i.e. setting up for best glide).

 

[Fly Navy]

I would teach a novice pilot (per the FAA guidlines) the above 4 steps. It is a procedure/memory thing. If the engine is dead pushing the power forward won't help, but it won't hurt either and it keeps them following a procedure. And, many times in light piston aircraft, this is actually enough to restart a dead engine - especially if the thing that caused the failure was a fuel problem (carb, mixture, etc.). Further, novice pilots don't have bingo profiles. They know max glide speed/configuration for the aircraft they are training in, but at their level breaking the stall is more important than trying to break the stall while maintaining a profile. Per the FAA, teach a private student to handle the most threatening problem first, than they can resume whatever else is going on (i.e. setting up for best glide).

I'll defer to your experience level over mine on this one. I can agree to that.