Feathered vs Windmilling Prop

[seagull]

I have never seen tgrayson post BS.

It might be worth your time and effort to go back through the thread and review what he is saying. This: "The argument that drag is reverse thrust means that the C-172 you fly has thrust reversers." ...tells me that you're not really tuned in to what he's getting at.

Just a friendly suggestion.

True. I would be very careful and have my research complete before challenging tgrayson on any objective issue. He is extremely meticulous in ensuring he has considered all the possible counter arguments. I am not sure I have ever caught him on anything, online or in person. He doesn't pretend to know everything, and will not offer an opinion unless he is very sure, in my experience.

 

[chuckles1225]

But there are centrifugal stop pins that prevent it from feathering below a certain RPM.

True, but I don't think that is what he was referring to when he said "locked" in feather. I do not know of any aircraft out there that have a physical mechanism to lock props in feather... the air does a good enough job by itself. If anyone knows of an aircraft that has a feather-locking system please enlighten me.

 

[PFGiardino]

wow, where did you go to flight school?

Something amiss? I learned about beta mode in a book. Never flown a turboprop...

 

[Douglas]

For the TGray
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[shdw]

True. I would be very careful and have my research complete before challenging tgrayson on any objective issue. He is extremely meticulous in ensuring he has considered all the possible counter arguments. I am not sure I have ever caught him on anything, online or in person. He doesn't pretend to know everything, and will not offer an opinion unless he is very sure, in my experience.

:yeahthat: And what steve said. I have only been here a year and have engaged in many discussions with him. Through research and some guidance from him and other posters, (sidetrack, where is fish on this topic) I learned that I certainly didn't understand things as well as I thought. In fact, in every case but two I was able to directly verify his information being correct from multiple sources.

For what it is worth, I posted a few times on this thread saying how I wouldn't complicate it like this. That does not mean I believed this is wrong. I understand his explanation and know it to be correct, I just felt it was too in depth for a private pilot. I would lean more towards its necessity being in commercial training.



And doug: :rotfl:

 

[Chief Captain]

So on turboprops with a beta setting on the prop control, the prop is really just windmilling? :hugerolleyes:

and drag is really just reverse thrust? :evenbigger rolleyes:

You're trolling, aren't you?

The argument that drag is reverse thrust means that the C-172 you fly has thrust reversers. Clearly that's not the case, now, is it?

Changing blade angle is ONE WAY of reversing thrust- turboprops use this method. Turbofans also have reverse thrust, and their blades are fixed (just like your 172) want to guess how they reverse thrust?

He didn't say that reverse thrust means a windmilling prop, he said that a windmilling prop creates reverse thrust.

 

[Chief Captain]

I put together an animated power point that makes visualizing the whole aerodynamic process a lot easier. If you do download it make sure you actually view the slide show and not just look at the slides individually in the editing mode, as they won't make any sense.

http://www.mediafire.com/?ndmdmrgjmzq

That is a VERY good slideshow. Would you mind if I used it to teach this topic?

 

[Matt13C]

True, but I don't think that is what he was referring to when he said "locked" in feather. I do not know of any aircraft out there that have a physical mechanism to lock props in feather... the air does a good enough job by itself. If anyone knows of an aircraft that has a feather-locking system please enlighten me.

Ah I figured there was some sort of lock that kept it from spinning.

 

[Mike H]

Yes, thank you.

Drag isn't reverse thrust, reverse thrust is drag. By definition. Any force that acts parallel and opposite the flight path is drag.

True, but that's not what you implied when you said:

Windmilling props generate reverse thrust. The faster they windmill, the greater the reverse thrust.

Glad to see you admit your error.

 

[tgrayson]

Glad to see you admit your error.

Why are you trying to be so obnoxious to someone who is trying to share knowledge with you? It reflects very poorly on you.

Both of my statements you quoted are equally correct.

 

[tgrayson]

I would be very careful and have my research complete

Thanks, I owe you another $5.

 

[tgrayson]

I put together an animated power point

Well done.

 

[chuckles1225]

That is a VERY good slideshow. Would you mind if I used it to teach this topic?

Thanks a lot. You absolutely may use it with your students.

 

[Chief Captain]

Thanks a lot. You absolutely may use it with your students.

Much appreciated.

 

[Chief Captain]

True, but that's not what you implied when you said:

"Windmilling props generate reverse thrust. The faster they windmill, the greater the reverse thrust."

Glad to see you admit your error.

What was the error? I'd like to think that most anybody on this board saw that the statement was perfectly valid.

 

[Mike H]

Why are you trying to be so obnoxious to someone who is trying to share knowledge with you? It reflects very poorly on you.

I'm merely trying to make sense of... whatever it is you're yammering on about

Both of my statements you quoted are equally correct.

So then you're saying a C-172 DOES have a thrust reverser when the prop is windmilling?

Wow, just wow.

 

[SteveC]

Actually I was fairly serious when I wrote:

I have never seen tgrayson post BS.

It might be worth your time and effort to go back through the thread and review what he is saying. This: "The argument that drag is reverse thrust means that the C-172 you fly has thrust reversers." ...tells me that you're not really tuned in to what he's getting at.

Just a friendly suggestion.

Really, there's no sense in getting worked up about a topic like this on an internet forum. If you don't understand what he's saying feel free to ask questions to get further clarification.

Right now the road that you are traveling is counterproductive on a website that is known for presenting opportunities to network with people that can help you in your career. You can look back through this thread and find numerous examples of people telling you that tgrayson is indeed someone that you can rely on for good solid information. Bashing on him in this manner does nothing except hurt your own credibility.

If you want to keep shooting yourself in the foot, well no skin off my teeth I guess.

*shrug*

 

[chuckles1225]

So then you're saying a C-172 DOES have a thrust reverser when the prop is windmilling?

Wow, just wow.

No sir, he is saying that a windmilling propeller on a C-172 produces an aerodynamic force acting opposite the direction of flight, *similar* to a thrust reverser on a turbine engine. Anybody who has lost engine power in a ME airplane knows what this force feels like. You sure seem committed to undermining tgrayson's explanation, yet you have not included any scientific reasoning into your posts, nor have you offered an alternative explanation.

 

[shdw]

I'm merely trying to make sense of
Wow, just wow.

Ok, my last try and I mean no disrespect with any of this. If your attempt is to make sense of this scenario, things like this don't help:

"whatever it is you're yammering on about"
"Wow, just wow."
":hugerolleyes:"
":evenbigger rolleyes:"
"You're trolling, aren't you?"
"Glad to see you admit your error."

These are personal attacks, they demonstrate no attempt on your part to understand the situation. You can compare them to an elementary school child cracking a momma joke when his peer makes an argument he cannot understand.

When you don't understand something, a better course of action is to question it. That demonstrates a willingness to learn and is certainly better received than a momma joke.

Finally, if you understand it but disagree with it, explain why. Present an argument and follow up with information that you feel is relevant to the discussion.

_______________________BREAK_______________________

Let's look at what was said, and see if it can be understood.

"Windmilling props generate reverse thrust. The faster they windmill, the greater the reverse thrust."

What wasn't said is, "reverse thrust is just a windmilling prop." That is how you read it though. Instead, it was explained that a windmilling prop has the same exact effect of an engine that has reverse thrust. If that doesn't help maybe this will:

Causes: Prop in beta range | Windmilling prop | Jet reverse thrusters
Result: Reverse thrust is generated



Your second question fell on this, "drag is really just reverse thrust." Now I have skimmed the forum again and do not see how you came to this conclusion. My assumption is you have issues with the definition of drag.

Drag: The force that acts parallel and directly opposite the path of flight.

The result is, any force that one puts on the aircraft that aligns itself in this manner, is drag. Reverse thrust, spoilers, moving the control surfaces, changing AOA, sticking your hand out to give some guy the finger, and so on all contain a vector force that acts parallel and directly opposite the flight path. The end result is drag, so reverse thrust is drag.

Hope that helps, and please take the advice of many here. It will be better for all of us.

 

[minitour]

Intake drag.

...

-mini