Sign in to follow this  
Followers 0
tkyler

The Horses Mouth - MU2 Props and Feathering

8 posts in this topic

Seems a Twitch streamer had a few comments about the Moo prop model and pointed some disparaging language in my direction.  My response attached as a matter of record.  I don't plan to discuss this further FYI.  I provide this for any of this streamers followers who might want to know my response on the topic.

 

Horses Mouth - XA MU2 Prop Feather.pdf

Edited by tkyler
1

Share this post


Link to post
Share on other sites

Hmm dont know much but thanks for all the efforts you put in.  Just one question, and i will dig a bit deeper. The flight idle position, is it a beta mode. The throttle control seems to start at flight idle, and needs to go into beta, to go to ground idle. Is this correct or one of the limitations you speak of.

 

Thanks again it is a challenge.

0

Share this post


Link to post
Share on other sites

I just want to say thank you for all your efforts and a very nice aircraft in X-Plane.  It is easy for people to criticize without knowing what really is possible or not possible without breaking something bigger at the end of the day, especially on an ever changing x-plane.  If someone thinks they have a solution pass it through to developers (in a nice way as possible suggestion) BUT thinking one knows more than the developer because you found something to me is very arrogant and a total lack of understanding what goes in behind the scenes in development.  Also those "genius" people, thinking they know everything, will never be good in a full product development because they do not see the whole picture and never will.  Just my 2 cents.

Once again thanks for a great aircraft and keep on doing the things you are doing. 

0

Share this post


Link to post
Share on other sites
On 10/30/2017 at 2:59 AM, mjrhealth said:

The flight idle position, is it a beta mode. The throttle control seems to start at flight idle, and needs to go into beta, to go to ground idle. Is this correct or one of the limitations you speak of.

The flight idle is not a beta mode, it is "the lowest range of prop governer mode"   The reason the throttle is where it is for now is due to my trying to obtain flat pitch props at startup.  In V10...if I initialized the levers to be between flight idle and ground idle, as per the manual, then Austin's code (using his flight model) would always feather the props, due to the way he modeled the beta/reverse regimes.   

Ground idle is indeed in the beta range.   The ground idle throttle position manually sets the prop pitch to a position that results in some positive thrust.  This thrust, in reality, is not insignificant and can result in quite a fast taxi speed.  A method some Moo pilots use during taxi, is to keep the levers at ground idle, and as the taxi speed build, apply brakes while simultaneously moving the levers towards reverse as needed.   I don't like using the term, "in reverse" because it implies a single state of some amount of reverse thrust.  As you move the levers aft from the ground idle position, you're changing the prop pitch such that they begin to generate negative thrust and full aft results in maximum negative thrust.  There is some point between ground idle and full reverse that will yield no thrust.  It is possible to operate in this range between ground idle and reverse, using the levers to control taxi speed.  The reason we did not do this in reality is because the positive thrust in this range was just too little....and we were impatient.  So we put it in ground idle, let the thing accelerate quickly to a decent speed and then slapped it in to reverse...back and forth. Not unlike driving in slow-moving, stop and go traffic.

On another note, It looks as though Austin has played with with turbine algorithm and I was unawares of some of the changes.  I am going to revisit this shortly to see if I can get things more closely aligned with the real thing regarding the lever action.

-tkyler

Edited by tkyler
1

Share this post


Link to post
Share on other sites

Hey Tom,

Thanks for your willingness to explain both the real MU-2 and your creation.  I think we sometimes forget this is a simulation and as such there are always compromises. I'm having a blast learning to flying her properly.  It sure is a handfull in a cross-wind, but I love the challenge! Keep up the great work!

0

Share this post


Link to post
Share on other sites
6 hours ago, tkyler said:

The flight idle is not a beta mode, it is "the lowest range of prop governer mode"   The reason the throttle is where it is for now is due to my trying to obtain flat pitch props at startup.  In V10...if I initialized the levers to be between flight idle and ground idle, as per the manual, then Austin's code (using his flight model) would always feather the props, due to the way he modeled the beta/reverse regimes.   

Ground idle is indeed in the beta range.   The ground idle throttle position manually sets the prop pitch to a position that results in some positive thrust.  This thrust, in reality, is not insignificant and can result in quite a fast taxi speed.  A method some Moo pilots use during taxi, is to keep the levers at ground idle, and as the taxi speed build, apply brakes while simultaneously moving the levers towards reverse as needed.   I don't like using the term, "in reverse" because it implies a single state of some amount of reverse thrust.  As you move the levers aft from the ground idle position, you're changing the prop pitch such that they begin to generate negative thrust and full aft results in maximum negative thrust.  There is some point between ground idle and full reverse that will yield no thrust.  It is possible to operate in this range between ground idle and reverse, using the levers to control taxi speed.  The reason we did not do this in reality is because the positive thrust in this range was just too little....and we were impatient.  So we put it in ground idle, let the thing accelerate quickly to a decent speed and then slapped it in to reverse...back and forth. Not unlike driving in slow-moving, stop and go traffic.

On another note, It looks as though Austin has played with with turbine algorithm and I was unawares of some of the changes.  I am going to revisit this shortly to see if I can get things more closely aligned with the real thing regarding the lever action.

-tkyler

Thanks for explanation. I tend to just flip into beta, and it taixs fine than use a little power to slow down as required. Could be worth while adjusting the Prop taxi indent so when the levers are in teh indent you can go into beta. At current you have to move levers a tad forward, But it is just something users will have to get to know.

0

Share this post


Link to post
Share on other sites

LOL< what a clown that guy is!  Straight from his horse's a$$ if you ask me, does the word 'narcissist' ring a bell?  Nice article Tom, loved it!
Was wondering what regulated blade angle, on power loss.  Thanks!

0

Share this post


Link to post
Share on other sites
On 11/1/2017 at 11:22 PM, tgw said:

......Was wondering what regulated blade angle, on power loss.  Thanks!

Sorry man, this one totally slipped by me.    The Moo utilizes what is called a NTS (negative torque sensor) system.    When the engine is driving the prop, the torque is in "one direction" and when the engine fails (power loss), the wind will then cause the prop to drive the engine and the torque will be in the "opposite direction"...or rather, 'negative torque'.  When that happens, the NTS system, which is a hydro-mechanical system, will cause the feather valve to open and allow the blade to rotate towards feather via the feather spring.  As the blade rotates towards feather, the wind force driving the blade will dimension and the negative torque ceases (it doesn't actually, but thats another discussion on how the NTS system works).  Anyhow...this cessation of negative torque on the NTS system usually happens before the blade has fully feathered though.  As such, the Mitsubishi documentation does not refer to the NTS system as an 'automatic feathering system', but rather a 'drag reduction' system.   To fully feather the prop to its minimal drag configuration, you still have to pull the condition lever back all the way to dump the remaining oil in the prop governor.

So to recap, in an engine failure, the prop would "mostly feather" rather quickly via the NTS system, but still have some drag....and you, as a saavy pilot would figure this out quickly and move the appropriate condition lever to full aft, and get that full feather / minimum drag configuration.

I've been playing with some new XP11 datarefs and think I can squeeze all this functionality in.  I'm having an issue with the engine start sequence currently and need some feedback from laminar.  Once I get past that, I'm going to test my NTS implementation and once I get that going, should be ready to issue a patch, 

-tkyler

Edited by tkyler
0

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0

  • Recently Browsing   0 members

    No registered users viewing this page.