BeechTalk - BT

Username Protected · **Posted:** 30 Sep 2015, 08:13

Username Protected wrote:

As far as the "extreme danger" on climb in a twin. I don't know what to say. I don't have any personal experience. All I know is that my 10,000 hr+ commercial pilot/flight instructor explained it to me this way, as well as my class instructor from flight school. Said that IF the one engine failed IN CLIMB that you literally could not react fast enough to stop from ending up upside down.

Gerry,

Either your instructor misspoke or maybe you misheard. That statement is disconnected from reality.

Best,

Username Protected · **Posted:** 30 Sep 2015, 08:19

Username Protected wrote:

As far as the "extreme danger" on climb in a twin. I don't know what to say. I don't have any personal experience. All I know is that my 10,000 hr+ commercial pilot/flight instructor explained it to me this way, as well as my class instructor from flight school. Said that IF the one engine failed IN CLIMB that you literally could not react fast enough to stop from ending up upside down.

Gerry,

Either your instructor misspoke or maybe you misheard. That statement is disconnected from reality.

Best,

Username Protected · **Posted:** 30 Sep 2015, 08:24

Gerry,

There is a step by step procedure for departures that, if followed, keeps you off your back and provides a predictable outcome based on weight, temp, and runway length. If you keep the power up OEI and let it bleed airspeed below VMC, yes bad things happen. That is why you follow the procedure.

Best,

Username Protected · **Posted:** 30 Sep 2015, 08:32

Username Protected wrote:

Gerry,

There is a step by step procedure for departures that, if followed, keeps you off your back and provides a predictable outcome based on weight, temp, and runway length. If you keep the power up OEI and let it bleed airspeed below VMC, yes bad things happen. That is why you follow the procedure.

Best,

I have no doubt. And I wasn't trying to suggest that twins aren't safe. This discussion is a departure of where I was originally going with an earlier discussion. How bout we end it here and move on.

The original discussion was talking about gyroscopic forces in climb in the Evo if someone were to use a TPE331 engine. With the engine spinning 30,000 rpm and the prop another 2,000 all in the same direction as well as adding a high angle of attack makes the TPE a not so ideal engine for the plane. Sure you could keep the angle of attack lower to minimize this effect, but then you are taking away one of the best parts of the Evo plane which is fast climbs to reduce fuel use during that part of flight. (or so it was explained to me by the engineer) Which (as it was explained to me) is why the PT6 has a counter rotating prop vs power section, reducing the gyroscopic effect leaving you to only needing to counter the asymmetric thrust of the prop.

Username Protected · **Posted:** 30 Sep 2015, 09:07

Gerry, I'm still voting with my original color scheme and a parachute........

I'm hoping that you come to your senses before they slap some paint on that bad boy.

When you flying it here. I want a ride bad!!

Username Protected · **Posted:** 30 Sep 2015, 09:12

Username Protected wrote:

Gerry, I'm still voting with my original color scheme and a parachute........

I'm hoping that you come to your senses before they slap some paint on that bad boy.

When you flying it here. I want a ride bad!!

It's going to paint in about a week. I think the orange will look good and it will be more unique. Lot's of blue Evo's already :peace:

. I'd love to give you a ride sometime. I'm sure I will be doing trips to Orlando shortly after the plane is done. Perhaps you could meet me there sometime?

Username Protected · **Posted:** 30 Sep 2015, 09:14

Username Protected wrote:

Gerry, I'm still voting with my original color scheme and a parachute........

I'm hoping that you come to your senses before they slap some paint on that bad boy.

When you flying it here. I want a ride bad!!

It's going to paint in about a week. I think the orange will look good and it will be more unique. Lot's of blue Evo's already :peace:

. I'd love to give you a ride sometime. I'm sure I will be doing trips to Orlando shortly after the plane is done. Perhaps you could meet me there sometime?

Username Protected · **Posted:** 30 Sep 2015, 09:23

Username Protected wrote:

It's going to paint in about a week. I think the orange will look good and it will be more unique. Lot's of blue Evo's already :peace:

. I'd love to give you a ride sometime. I'm sure I will be doing trips to Orlando shortly after the plane is done. Perhaps you could meet me there sometime?

Orlando's so close I could even drive there.....I'm in.

Username Protected · **Posted:** 30 Sep 2015, 10:32

Username Protected wrote:

You're missing the point on the gyroscopic forces on a twin. Because there are two engines on the edges of the plane they sort of "cancel" each other out.

I don't see why that would be the case. A pitch up would cause a yaw moment in each engine, and with them turning the same direction, the yaw would be in the same direction, so they would add.

I've never noticed gyroscopic forces in my plane or any turbine airplane. They simply aren't that significant.

Quote:

All I know is that my commercial pilot/flight instructor explained it to me this way. Said that IF the one engine (specifically the right or left engine, can't remember which) failed in initial climb at high angle of attack that you literally could not react fast enough to stop from ending up upside down.

Either you didn't hear them correctly, or they made stuff up to fill in their ignorance. A teacher who says "I don't know" is superior to one that makes stuff up to never say that.

Quote:

As far as the gyroscopic forces on a single, when the internals of the engine and prop are all spinning in the same direction AND you include asymmetric thrust

How did the single get asymmetric thrust?

Quote:

that is where the TPE is a problem on a single with high power to weight ratio. This concept was explained to me by the engineer that helped design the Evolution.

I don't believe this. Sounds like something made up to justify engine choice.

In standard propeller rotation (clockwise from pilot's seat), a pitch UP causes a yaw RIGHT. But engine TORQUE and P-FACTOR causes a YAW/ROLL LEFT, so the gyroscopic forces are actually help cancel the torque and P factor effects.

Here's commentary on that, without any math:

http://www.rapp.org/archives/2008/09/gy ... recession/

Mike C.

Username Protected · **Posted:** 30 Sep 2015, 10:58

Username Protected wrote:

Quote:

that is where the TPE is a problem on a single with high power to weight ratio. This concept was explained to me by the engineer that helped design the Evolution.

I don't believe this. Sounds like something made up to justify engine choice.

In standard propeller rotation (clockwise from pilot's seat), a pitch UP causes a yaw RIGHT. But engine TORQUE and P-FACTOR causes a YAW/ROLL LEFT, so the gyroscopic forces are actually help cancel the torque and P factor effects.

Here's commentary on that, without any math:

http://www.rapp.org/archives/2008/09/gy ... recession/

Mike C.

Look, I'm sorry but if you have data to support your argument then that's one thing. I spoke to an engineer on this very topic. An engineer that has designed and built and airplane. I'm sorry to say I'm more inclined to believe what he says. I just simply don't know enough about you and your credentials on the matter to change my mind simply because you don't believe it.

Edit: The engineer specifically looked into adding the option to install a TPE331. That is why he had the information on the engine and the potential gyroscopic issues that he did. It wasn't because he wanted to eliminate an engine. He wanted to make it an option but discovered it may not be a good choice given the particular aircraft. Again, this issue will only effect certain types of aircraft. Such as the Evo. Most other aircraft may not have much issue.

Username Protected · **Posted:** 30 Sep 2015, 13:54

In a single engine P factor can be called asymmetric thrust. Compared to asymmetric thrust in a twin it's very minor.

It has something to do with the thrust vector moving around the prop disk at high angles of attack.

Not sure where you are going with the twin engine stuff?

Username Protected · **Posted:** 30 Sep 2015, 15:02

Username Protected wrote:

In a single engine P factor can be called asymmetric thrust. Compared to asymmetric thrust in a twin it's very minor.

It has something to do with the thrust vector moving around the prop disk at high angles of attack.

Not sure where you are going with the twin engine stuff?

I forget, lol

Username Protected · **Posted:** 02 Oct 2015, 14:51

Username Protected wrote:

In a single engine P factor can be called asymmetric thrust. Compared to asymmetric thrust in a twin it's very minor.

It has something to do with the thrust vector moving around the prop disk at high angles of attack.

Not sure where you are going with the twin engine stuff?

It's very possible I was off base with the twin stuff. I need to learn when to stop sometimes lol.