Sign in to follow this  
Slick9

Realair Duke Turbine v2...

Recommended Posts

I just started flying this plane and I love it.  There is a little bit of a lack of information out there, so I have a few questions in the hopes that there are some experienced DuKe Turbine drivers out there.

 

enroute from KMIC to KCMI this weekend, I suffered a right engine failure. I didn't have the oil doors open because I was in cruise @ FL290, and I wasn't paying attention to the oil temps (thought they only had to be watched on climb out at slow speeds).   Anyway, the initial diversion was fine from altitude. As i got down to around 3,000 feet i started experiencing extreme yawing motion.  In order to turn into the good engine I almost had to be in a 90 degree bank (just trying to line up with the runway).  I had the prop on the bad engine feathered and was only on approach flaps.  Is this normal behavior with this aircraft or am i doing something wrong?  

 

Also wanted to check and see if it's normal to pull the Prop RPM lever back during cruise to reduce the rpms to about 2000?

 

FInally, I've seen people say they're getting about 60 to 66 gph with this bird, my typical cruise set up is about 88-90% of NG, RPMs pulled back to 2000, fuel flow of about 25 to 26 gph, this gives me ground speed of 275 to 300 knots, wind dependent.  Does this sound normal?

 

And finally I've been looking for a larger selection of repaints for the aircraft but have only found very few.  I've checked the library here and at flightsim, any other ideas on where i might find more repaints?

 

Thnx for your time!!!

 

 

Richard Bansa

Share this post


Link to post
Share on other sites
Help AVSIM continue to serve you!
Please donate today!

Been a while since I've flown the turbine

 

But I recall Zane Gard (former user here) who has actually flown the real N157JT - say that 1900 rpm was normal cruise

 

I can't recall the torque but VMO is 198 kias -gets you around 250/260 KTAS at FL250.

 

Also FL290 would typically be too high because it creates a pressure differential higher than allowed (can't recall what that number is - maybe 4.7 psi)

 

And if you're trying to sim realistically you need supplemental O2 above FL250 which the Duke doesn't have - although you can always pretend as I sometimes do.

 

Your issue about single engine approach seems

odd - I've never experienced something so drastic... How unbalanced was the fuel?

Share this post


Link to post
Share on other sites

 

 


As i got down to around 3,000 feet i started experiencing extreme yawing motion. In order to turn into the good engine I almost had to be in a 90 degree bank (just trying to line up with the runway).

 

You don't say, but are you compensating for the yaw induced by the remaining engine with rudder?  With the right engine failed, you'd need to be compensating with a lot of left rudder.  The old expression is "dead foot, dead engine", basically meaning that you'll be using a lot of the opposite foot to compensate.  If you know this and are doing so, then nevermind.  :-)

 

Scott

Share this post


Link to post
Share on other sites

You don't say, but are you compensating for the yaw induced by the remaining engine with rudder?  With the right engine failed, you'd need to be compensating with a lot of left rudder.  The old expression is "dead foot, dead engine", basically meaning that you'll be using a lot of the opposite foot to compensate.  If you know this and are doing so, then nevermind.  :-)

 

Scott

 the other important one is "...raise the dead...."

Share this post


Link to post
Share on other sites

Watch your airspeed when on one engine and slow , sounds like you might have gotten too slow and dropped below minimum controllable airspeed with an engine out.... this is very easy to do in the T Duke.

Share this post


Link to post
Share on other sites

 

 


the other important one is "...raise the dead...."

 

Never heard that one, but I like it.

 

 

 


Watch your airspeed when on one engine and slow , sounds like you might have gotten too slow and dropped below minimum controllable airspeed with an engine out.... this is very easy to do in the T Duke.

 

Excellent point.

 

Scott

Share this post


Link to post
Share on other sites

Thanks for the replies guys!!!

 

Ryan I was reading a post by a real tduke driver. He said that even though his tduke is only certified to FL250 he routinely goes to FL300. He does carry a bottle of supplemental oxygen, but he noted that even at FL300 the pressurization diff tops out at the 4.7 max, that was the same result I got in the sim, even at FL 290 the diff was 4.7 and the cabin altitude stopped at 10,500. But we'll pretend I have a bottle of supplemental O2.

 

I think Allen was right about my speed dropping too low for single engine ops. My fuel tanks were balanced to within a few pounds so that shouldn't have been an option - I was riding the rudder pretty hard but the plane was just hard to control, but now that I think of it, I was using dual engine ops speed on my approach.

 

Richard

Share this post


Link to post
Share on other sites

I do a lot of my flying in SoCal (pilot edge) and it's tough to keep the differential within tolerance - but the Midwest especially this time of year is doable.

Share this post


Link to post
Share on other sites

I've seen people say they're getting about 60 to 66 gph with this bird, my typical cruise set up is about 88-90% of NG, RPMs pulled back to 2000, fuel flow of about 25 to 26 gph, this gives me ground speed of 275 to 300 knots, wind dependent. Does this sound normal?
[/quote

 

The 60 to 66 gph figures are of course 'combined' fuel flow; e.g., the total fuel burn from both engines.     Are you perhaps confusing these figures with individual engine fuel flow?    

Share this post


Link to post
Share on other sites

I've seen people say they're getting about 60 to 66 gph with this bird, my typical cruise set up is about 88-90% of NG, RPMs pulled back to 2000, fuel flow of about 25 to 26 gph, this gives me ground speed of 275 to 300 knots, wind dependent. Does this sound normal?

[/quote

 

The 60 to 66 gph figures are of course 'combined' fuel flow; e.g., the total fuel burn from both engines.     Are you perhaps confusing these figures with individual engine fuel flow?    

 

I'm getting 25 to 26 gph per engine for a total burn of around 50 gph...

Share this post


Link to post
Share on other sites

I'm getting 25 to 26 gph per engine for a total burn of around 50 gph...

 

What is the OAT when you are seeing 50 gph?      On the Beechtalk forums, a real turbine Duke pilot had this observation:

 

"Cruise power is really a function of how much your willing to spend? Generally you'll need to start reducing torque to keep ITT in check when you get up above FL250. Depending on OAT I can usually have 1000 lbs of torque +- 50 lbs to keep the my fuel flow around 33-34 gph per side for 66-68 total. I've found 2000 prop rpm is a happy number. If it's warmer than standard you may be ITT limited in the climb above FL260 but rarely do I see that. At those fuel flows at FL270-280 I will see between 265-270 kts true, indicating about 170-175. If it's cool enough and want to push more fuel thru it, push the levers forward until you limit the torque at 1200 or ITT at 760. It's generally not a problem to make the RTD go over 280 kts true, you'll just be running the ITT near the limit and burning 75-80 gph."

 

Share this post


Link to post
Share on other sites

What is the OAT when you are seeing 50 gph?      On the Beechtalk forums, a real turbine Duke pilot had this observation:

 

"Cruise power is really a function of how much your willing to spend? Generally you'll need to start reducing torque to keep ITT in check when you get up above FL250. Depending on OAT I can usually have 1000 lbs of torque +- 50 lbs to keep the my fuel flow around 33-34 gph per side for 66-68 total. I've found 2000 prop rpm is a happy number. If it's warmer than standard you may be ITT limited in the climb above FL260 but rarely do I see that. At those fuel flows at FL270-280 I will see between 265-270 kts true, indicating about 170-175. If it's cool enough and want to push more fuel thru it, push the levers forward until you limit the torque at 1200 or ITT at 760. It's generally not a problem to make the RTD go over 280 kts true, you'll just be running the ITT near the limit and burning 75-80 gph."

 

 

The OAT for the whole trip hovered around -40F.  I read this excerpt on another forum, and those figures were part of what made me start wondering about the numbers I was seeing.   My torque was around 650 lbs per engine w/ about 2080 prop RPM, now granted I did have tail winds of around 25kts so that helped with the speed, but my fuel flow seems off.

 

Richard

Share this post


Link to post
Share on other sites

That post you quoted is running them at 1200 lbs torque if I'm reading it correct per engine, where as you are lumbering along at 650 lbs torque?  That would be the fuel difference if I'm following the thread properly.

 

1200 lbs torque per side is what gets the 75-80gph mentioned, that's almost twice the power you are pushing.

 

Maybe I'm confused though ha, typing this while finishing up some work stuff, ignore if I'm misunderstanding.

Share this post


Link to post
Share on other sites

Found this video on youtube that gives a real good insight on what it's like, and how to,  to fly the "duke"

 

Jlund

Share this post


Link to post
Share on other sites

Wow so all these owners must have supplemental oxy with them....  as I understood the service ceiling was FL250... apparently not so.  I wonder how many actually have the supplemental...

Share this post


Link to post
Share on other sites

1900 RPM and 1000 ft lbs @ 190 kts IAS is my standard cruise and at that I burn a well documented average of 63 GPH. I log burn for all of my flights and have tweaked my performance table at Fltplan.com such that my flight plan from there and my actual burn is +/- 2%~3%. 

 

Here is my kneeboard for TDv2. This based on -10°C OAT, which is a good year round norm for the low to mid FL2xx range. Of course warmer or colder OAT will affect actual.

 

This is an earlier version than what I currently use. I would need to cut a new .pdf to upload with my current but the most notable change is that I have corrected the (2) VFE flaps notations: 15° flaps @ 174 kts IAS or below; 30° flaps @ 134 kts IAS or below.

 

****************

Removed the kneeboard I originally posted tonight and replaced it below with my current version. Took me a bit to convert the pdf to jpeg, upload it to my photo server, and link to it.

Share this post


Link to post
Share on other sites

Here is my current kneeboard, and my sheet of Vref speeds for the TDv2.

 

NOTE: The fuel flow references are Per Engine !!!

 

Turbine%20Duke%20Operation%20V2-X3.jpg

 

 

Turbine%20Duke%20Vrefs-L.jpg

Share this post


Link to post
Share on other sites

I actually have a copy of the STC flight manual for the Turbine Duke put out by Rocket Engineering in Spokane, but it really is sketchy about actual cruise performance figures.     I'm guessing an engine operating manual put out by Pratt and Whitney would yield far more actual data like inflight fuel flows, etc.    

Share this post


Link to post
Share on other sites

 

 


I actually have a copy of the STC flight manual for the Turbine Duke put out by Rocket Engineering in Spokane, but it really is sketchy about actual cruise performance figures.     I'm guessing an engine operating manual put out by Pratt and Whitney would yield far more actual data like inflight fuel flows, etc.    

 

Good way to compare the real life Turbine Duke to this model, but the fuel burn question was about the performance characteristics of this model.

Share this post


Link to post
Share on other sites

looking at Frank's numbers as well as other figures, I guess I've been under utilizing the power of the turbine engines by running them at only 650 lbs of torque and 85-89% of NG, however the good things with that is with good tail wind you can stretch the range by a few hundred miles.  

 

Regarding cruise altitude and supplemental oxygen - on one forum that I was reading one of the Tduke owners who regularly cruises around FL300 said he believed the FAA certification of the duke to only FL250 had to do with attempting to boost survivability of an explosive decompression. He said he knew his Duke could safely handle pressurization up to FL350 and as far as he was concerned in an aircraft the size of the Duke, an explosive decompression at FL250 would be just as fatal as one at FL350.  Another Tduke owner had replaced the original pressurization system in his aircraft with a Beech Queen Air pressurization system.  All very interesting.

 

Richard

Share this post


Link to post
Share on other sites

That is interesting actually....  I'm not saying I don't sometimes pretend I have supplemental... but typically I don't take the T Duke above FL250...  Now the Legacy....   :wink:

Share this post


Link to post
Share on other sites

FL350? Not enough reward for the risk, or for the investment, considering outlay and then stress on airframe and power plants from the additional hours of climbs, which over time increase costs.  Bragging rights? 

Share this post


Link to post
Share on other sites

You know something? to further this discussion on TDv2 fuel burn performance at cruise....  If you have a F1 GTN GPS in your RealAir Turbine Duke v2 you can either look at the FF gauge in the engine gauges stack, point your mouse at one of the FF gauges to read the tool tips, or better yet navigate to this Fuel Planning page of the GTN and you can easily see your FF when in any phase of flight.  (see red oval in image below).  Here I am just beginning to slow before beginning my initial descent from FL240 into Daytona for tonight's twin 150 mile qualifying races and staying for this weekends Daytona 500.  So my FF seen here is in the first stage of reduction while still at level flight.

 

2016-2-18_16-1-11-811-X2.jpg

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