Constant Speed Prop and Steep Turns

[kontiki]

I recently got my high performance endorsement in a C182-T. During the checkout the CFI tried to explain how the CS prop made it a lot easier to fly a steep turn, because it didn't slow down. So you didn't need to add any power.

It was a mauch easier steep turn to fly, the airplane held altitude much more easily. It was easier than in the Arrow too, but the 182 has 230 HP, while the Arrow 200.

Ive got a few hours in a complex Arrow already, so the CS prop really isn't new, but I really didn't follow her explanation.

Can someone explain how single engine steep turns with a fixed pitch are different from a CS prop, single engine?

Thanks

 

[dmspilot]

Your instructor doesn't make any sense. They aren't different.

 

[gismo]

Your instructor doesn't make any sense. They aren't different.

There is a difference but the CFI overstated the effect (or the OP misunderstood what the CFI meant). With a CS prop the RPM won't drop during the turn and therefore the power won't be reduced either. But because the increased g loading requires a more lift with associated increased AoA and induced drag, the airplane will still slow down if you don't increase power, just not as much as it does with a fixed pitch prop. When the pitch is fixed the RPM decreases when the airspeed drops and that causes the engine to produce less power so it's sort of a double whammy (less power produced, more power required).

But if you want to maintain a constant speed equal to your speed in level flight while entering and completing a turn, you will need to add pretty much the exact same power increase with either prop.

 

[flyingmoose]

There is a difference but the CFI overstated the effect (or the OP misunderstood what the CFI meant). With a CS prop the RPM won't drop during the turn and therefore the power won't be reduced either. But because the increased g loading requires a more lift with associated increased AoA and induced drag, the airplane will still slow down if you don't increase power, just not as much as it does with a fixed pitch prop. When the pitch is fixed the RPM decreases when the airspeed drops and that causes the engine to produce less power so it's sort of a double whammy (less power produced, more power required).

But if you want to maintain a constant speed equal to your speed in level flight while entering and completing a turn, you will need to add pretty much the exact same power increase with either prop.

Yes that.

 

[NineThreeKilo]

Uhh what?

I fly a C208B 900 caravan, it's got a CS 110" 4 blade prop and steep turns are way easier in a fixed prop 7ECA. Just becuse the prop stays at a certain percentage of RPM doesnt make the turn easier per say, yea in a decent it's nice to dial the speed in and not really worry about overspeed, but in a steep turn.....

What's your CFI's background and experience??

 

[Skylane81E]

Uhh what?

I fly a C208B 900 caravan, it's got a CS 110" 4 blade prop and steep turns are way easier in a fixed prop 7ECA. Just becuse the prop stays at a certain percentage of RPM doesnt make the turn easier per say, yea in a decent it's nice to dial the speed in and not really worry about overspeed, but in a steep turn.....

What's your CFI's background and experience??

Little more of a difference between your two examples than a 172 and a 182 chief.

Easiest steep turns I have ever done were in a PA31-350, lots of power, very stable and no p factor as the AOA increased

 

[flyingmoose]

Uhh what?

I fly a C208B 900 caravan, it's got a CS 110" 4 blade prop and steep turns are way easier in a fixed prop 7ECA. Just becuse the prop stays at a certain percentage of RPM doesnt make the turn easier per say, yea in a decent it's nice to dial the speed in and not really worry about overspeed, but in a steep turn.....

Why? An airplane is an airplane. The caravan and the 7eca turn the same way. CS or not, airspeed control is still going to be power related. Maybe its a more docile airframe you are trying to say? idk.

What's your CFI's background and experience??

Is this where we get out our pitchforks and do a good ol fashion internet lynching of a CFI who might of said something?

 

[dell30rb]

Is this where we get out our pitchforks and do a good ol fashion internet lynching of a CFI who might of said something?

Still the OP's instructor did not make much sense. For a FP plane you roll into the turn, add backpressure and throttle for a level turn maintaining airspeed.

In a CS prop airplane, you roll into the turn, and add backpressure and throttle. I don't see how its any easier.

Matter of fact, i'd say the fixed pitch is almost easier to deal with because you can hear your power changes.

 

[Geico266]

It amazes me how some CFIs make things overly complicated.

Fly the airplane.

 

[Skylane81E]

Still the OP's instructor did not make much sense. For a FP plane you roll into the turn, add backpressure and throttle for a level turn maintaining airspeed.

In a CS prop airplane, you roll into the turn, and add backpressure and throttle. I don't see how its any easier.

Matter of fact, i'd say the fixed pitch is almost easier to deal with because you can hear your power changes.

You add throttle? I just turn the plane

 

[Jaybird180]

You add throttle? I just turn the plane

And therein lies the rub...it's a matter of technique. I was taught to do it without adding throttle, I didn't like the result and decided to add power during my student solo practice. Found the correct sight picture that way too.

 

[poadeleted20]

You add throttle? I just turn the plane

Depends on technique. Some people feel the need to slow to maneuvering speed before stating the steep turn. Then, when they get the turn established, the added drag of extra AoA needed to increase total lift component to make up for the loss of vertical component due to bank angle causes the aircraft to decelerate nearly to stall speed (depending on actual bank angle and aircraft characteristics) in its accelerated condition. Then they need to add power to get back to a speed which provides an adequate stall margin. Personally, I just leave the throttle where it was in cruise and let that extra drag decelerate me to maneuvering speed as I increase AoA along with bank angle to maintain altitude in the entry.

 

[EdFred]

You add throttle? I just turn the plane

How do you maintain your airspeed and maintain altitude without adding power?

 

[Skylane81E]

How do you maintain your airspeed and maintain altitude without adding power?

I don't, I find the airspeed decay acceptable

 

[poadeleted20]

How do you maintain your airspeed and maintain altitude without adding power?

The PTS calls for doing this maneuver at maneuvering speed, so if you start at cruise, you don't need to add power -- the plane decelerates from cruise to Va as you load the wing without changing throttle. Makes for a much simpler entry and exit.

 

[dell30rb]

You add throttle? I just turn the plane

The G's you pull in a steep turn adds induced drag to the plane. Gotta add throttle or you'll slow down.

 

[EdFred]

I don't, I find the airspeed decay acceptable

For the commercial ride, the examiner may not.

 

[dell30rb]

The PTS calls for doing this maneuver at maneuvering speed, so if you start at cruise, you don't need to add power -- the plane decelerates from cruise to Va as you load the wing without changing throttle. Makes for a much simpler entry and exit.

I thought per the PTS you need to maintain entry airspeed + or - 10kts

Task A: Steep Turns (ASEL and ASES)
References: FAA-H-8083-3; POH/AFM.
Objective: To determine that the applicant:
1. Exhibits satisfactory knowledge of the elements related to
steep turns.
2. Establishes the manufacturer’s recommended airspeed or if
one is not stated, a safe airspeed not to exceed VA.
3. Rolls into a coordinated 360° turn; maintains a 45° bank.
4. Performs the task in the opposite direction, as specified by
the examiner.
5. Divides attention between airplane control and orientation.
6. Maintains the entry altitude, ±100 feet, airspeed, ±10 knots,
bank, ±5°; and rolls out on the entry heading, ±10°.

 

[EdFred]

The PTS calls for doing this maneuver at maneuvering speed, so if you start at cruise, you don't need to add power -- the plane decelerates from cruise to Va as you load the wing without changing throttle. Makes for a much simpler entry and exit.

From the Commercial PTS:

1. Exhibits satisfactory knowledge of the elements related to steep turns.
2. Establishes the manufacturer’s recommended airspeed or if one is not stated, a safe airspeed not to exceed VA.
3. Rolls into a coordinated 360° steep turn with at least a 50° bank, followed by a 360° steep turn in the opposite direction.
4. Divides attention between airplane control and orientation.
5. Maintains the entry altitude, ±100 feet, airspeed, ±10 knots, bank, ±5°; and rolls out on the entry heading, ±10°

Establishes the speed, THEN start the turn. Not let the speed bleed down during the turn.​

 

[Skylane81E]

For the commercial ride, the examiner may not.

Good thing I'm a private pilot

I have done them at a constant speed, does require more work, and a throttle application, but very do-able.

 

[EdFred]

Good thing I'm a private pilot

I have done them at a constant speed, does require more work, and a throttle application, but very do-able.

I will have to go do some in the Comanche at 45°, but I'm pretty sure my speed will drop more than 10kts - which is still a bust.

 

[dmspilot]

Check the Airplane Flying Handbook and Private and Commercial PTSes. An FAA steep turn requires you to enter at or below maneuvering speed and add power to maintain a constant airspeed.

 

[dell30rb]

I will have to go do some in the Comanche at 45°, but I'm pretty sure my speed will drop more than 10kts - which is still a bust.

I'd think so. But for the private most examiners are just concerned that you stay coordinated and make a decent turn. If you can do it without climbing 200 feet or entering a sprial dive that is.

 

[poadeleted20]

Glad to see a few people actually read the PTS.

 

[wabower]

Since I know that maintaining speed will be required for future ratings and that the process isn't all that complicated to learn, I teach them the same way no matter which rating is involved. Whether it's recency, primacy, consistency or whatever it's always the same.

I strongly believe that teaching all pilots to all pilots to instinctively nudge the power lever when entering a steep turn would significantly lessen the accidents from moose turns and other rubber-necking.

 

[Silvaire]

The bottom line for the OP - Constant Speed prop means engine RPM is constant, not airspeed.

 

[oldShar]

"From the Commercial PTS:
Quote: 1. Exhibits satisfactory knowledge of the elements related to steep turns.
2. Establishes the manufacturer’s recommended airspeed or if one is not stated, a safe airspeed not to exceed VA.
3. Rolls into a coordinated 360° steep turn with at least a 50° bank, followed by a 360° steep turn in the opposite direction.
4. Divides attention between airplane control and orientation.
5. Maintains the entry altitude, ±100 feet, airspeed, ±10 knots, bank, ±5°; and rolls out on the entry heading, ±10°"

That's probably a good benchmark for showing whether one can control airspeed, but otherwise why would one slow to Va?

A Normal Category plane that can't handle a 60-65* banked turn isn't airworthy and a pilot that allows signficant G-load variances during the turn is ham-fisted

 

[EdFred]

"
That's probably a good benchmark for showing whether one can control airspeed, but otherwise why would one slow to Va?

Because that's what the PTS says. Same reason we do ground reference maneuvers at certain altitudes - because that's what the PTS says.