1 hour ago, martinboehme said:

 

As I say, this is just what works for me. Would appreciate insights from others on how they operate the piston Duke.

I don't fly dukes but I do work air traffic and the piston dukes I see typically cruise from 17k to the low 20s for a long flight.  I've never seen a piston duke in the high 20s.  There's honestly not many pistons in that altitude stratum.  All your turbocharged twins typically fly high teens to occasionally low 20s.

12 minutes ago, ryanbatc said:

I don't fly dukes but I do work air traffic and the piston dukes I see typically cruise from 17k to the low 20s for a long flight.  I've never seen a piston duke in the high 20s.

Thanks for the insight!

I imagine this may have to do with the fact that the pressurized cabin on the Duke (and probably most pressurized piston twins) only allows a relatively low differential pressure. IIRC a cabin altitude of 8,000 ft can only be sustained up to FL 220. So rather than use supplemental oxygen ("I got a pressurized airplane so I don't have to wear a cannula!"), I imagine many operators stay lower than the airplane is theoretically capable of and accept the slightly higher fuel burn and slightly lower speed.

Or are there any other reasons not to exploit the 30,000 ft ceiling? 

32 minutes ago, ryanbatc said:

I don't fly dukes but I do work air traffic and the piston dukes I see typically cruise from 17k to the low 20s for a long flight.  I've never seen a piston duke in the high 20s.  There's honestly not many pistons in that altitude stratum.  All your turbocharged twins typically fly high teens to occasionally low 20s.

Yes, mid-teens to low twenties would be typical for a turbocharged pistion. Even though the Duke is pressurized, above FL280 or so the cabin altitude would be above 10,000 feet, meaning the pilot (at least) should use supplemental oxygen.

I suppose if going that high would allow one to take advantage of a booming jet stream tailwind, it might be worth it, but otherwise I think most operators of piston Dukes would choose a lower max cruise altitude. Cabin heating becomes an issue as well when OATs drop into the -30C range or lower.

27 minutes ago, martinboehme said:

Or are there any other reasons not to exploit the 30,000 ft ceiling? 

I think the plane actually cruises fastest at fl240. I will usually only go above that for either testing a new aircraft or to find the best weather. Especially favourable winds and storm cloud avoidance.

2 hours ago, martinboehme said:

As I say, this is just what works for me. Would appreciate insights from others on how they operate the piston Duke.

It makes sense to me to start leaning the mixture above, say 10,000ft (for best climb power). At least by 20,000ft to prevent the complete loss of power when passing through CA. When MP starts to drop this is imminent, hence leaning then is much too late, as the engines will fail within seconds of the MP drop. 

I would lean ROP for best power. Then, at cruise I might lean ROP/LOP depending on whether I prefer max power or best fuel economy. The manual explains very well how to do this using the EDM. 

On descent I guess it makes sense to enrichen below 10,000ft. 

23 minutes ago, Cpt_Piett said:

It makes sense to me to start leaning the mixture above, say 10,000ft (for best climb power).

Why though? The engine is still "seeing" the same manifold pressure that it saw at sea level, and will continue to do so for at least another 10,000 feet. As far as the engine is concerned, nothing has changed - so why change the mixture?

24 minutes ago, Cpt_Piett said:

When MP starts to drop this is imminent, hence leaning then is much too late, as the engines will fail within seconds of the MP drop. 

This hasn't been my experience. From the point where MP starts to drop, it was almost another  4,000 more feet until the engine quit (when I didn't lean). That should be enough time to start leaning.

If you're climbing at full power and start leaning before critical altitude, then you're reducing your detonation margin. That can't be good? 

1 hour ago, martinboehme said:

Why though?

I'm not an expert on these aircraft. Still got a lot to learn. I get the impression that you are more knowledgeable, which of course is fine. Great discussions in this thread, anyway. 

Edited May 18, 20242 yr by Cpt_Piett

On 5/10/2024 at 1:51 AM, mmcmah said:

Has anyone successfully landed a Duke using an ILS? I activate Approach mode when approaching the FAF, it lights up and then the the plane kind of loses track of both the localizer as well as the glideslope. This is with the TDS GTN750xi and Nav1 tuned to the right frequency.

 

On 5/10/2024 at 10:01 AM, ryanbatc said:

SU14 or beta 15?  As I understand the default autopilot logic doesn't have an APR mode during VLOC operations.  And when I mean I default I mean the old before WT made a new system.  Sometimes you have to fly on HDG mode longer than I would irl before engaging APR. 

or it could be the bug associated with the GNS in su14.

I tried my first ILS approach in the Turbine Duke tonight using the TDS GTN750 and also could not get it to couple to the approach using APR mode in VLOC.

Is it supposed to be able to couple to the approach?

The greatest airplane of all time that ever was released to bring flight simulation to the absolute next level!! After perfectionizing a few details here and there in the cockpit and interior (because I have a very exclusive taste in carpets, and the heater know labels where a bit misaligned) she is now now ready to roll out in her full piston glory.

The new master cooler rotating switch. Based on real Beechcraft 60 cockpit photos and cooler than ever before!

 

Edited May 20, 20242 yr by JetCat

1 hour ago, regis9 said:

 

I tried my first ILS approach in the Turbine Duke tonight using the TDS GTN750 and also could not get it to couple to the approach using APR mode in VLOC.

Is it supposed to be able to couple to the approach?

Works just fine.  I have no idea what happens with the VLOC button, I just select the ILS frequency after picking the approach in the PROC page.  I never press the GPS/VLOC button.  It's worked perfect for me on ILS or RNAV/LPV glidepaths down to minimums each time.

I'm not noticing any change in sound when using the beta range. Not sure if this is intended?

2 hours ago, Orlaam said:

I have no idea what happens with the VLOC button, I just select the ILS frequency after picking the approach in the PROC page.  I never press the GPS/VLOC button.  It's worked perfect for me on ILS or RNAV/LPV glidepaths down to minimums each time.

I think it needs to be kept in GPS mode when an autoflight ILS approach is selected in GPS after having followed the mangenta line.

VLOC is in action when using the good old NAV1 and NAV2 radios or that superawesome Black Square KNS-80 / 81 devices.

But not 100% sure because this Yedi still learning the richly layered ways of GA-flying is. (No Yoda smiley in the smiley menu that´s sad!) I have done an ILS-autoland only once a few months ago in a GA-plane with a GNS530 and I have no idead how this is done with a GTN750. But luckily there are so many great YouTube tutorial videos for avid aviators and the GTN750 fits perfectly in the Turbine Duke so it is worth learning. 🙂

On 5/18/2024 at 8:09 PM, martinboehme said:

Why though? The engine is still "seeing" the same manifold pressure that it saw at sea level, and will continue to do so for at least another 10,000 feet. As far as the engine is concerned, nothing has changed - so why change the mixture?

This hasn't been my experience. From the point where MP starts to drop, it was almost another  4,000 more feet until the engine quit (when I didn't lean). That should be enough time to start leaning.

If you're climbing at full power and start leaning before critical altitude, then you're reducing your detonation margin. That can't be good? 

Exactly. The whole point of the turbocharger is to NOT to have to do ANY mixture fiddling until AFTER critical altitude. The fact the airplane is less likely to die on you if you do fiddle below CA is simple evidence of a major flaw in the modeling. You should never need to level off DURING a climb or descent to fine tune the mix for safety. 

I've issued a NOTAM to my one man airline stipulating the Duke B60 factory and grand models must NOT be flown above FL 180 for safety until the planes are rectified. The turbine model is to be used for higher cruising which makes more sense anyway as it's a no brainer using that for the longer flights. 

On an approach using any coupled vertical guidance I've noticed the ap completely ignores glide scope altitude override logic. Would like this to me confirmed as realistic or a bug? 

In every other add on in every sim my procedure has been (from IRL recommendations) to dial in the missed approach altitude as soon as the glide scope is captured on an ILS or Lnav + V approach. It is then possible to set the MA altitude regardless of whether it's currently set under or over present altitude as glide scope coupling OVERRIDES normal vertical profiles. In the Dukes setting any MA altitude during glide scope coupling final approach phase KILLS the approach. I've had the planes level off if set below and actually start climbing again if set above and then of course that's your approach knackered. 

Btw the only time your MA would be lower than current altitude during actual glide scope capture would be if you pressed APPR a little early as FAF is almost always BELOW MA. 

If you want to test this just press APPR above current altitude setting as soon as you are receiving the relevant guidance and the plane WILL level off at set alt instead of following glide scope down to threshold. 

OR. Press APPR below glide path as is normal procedure (but it doesnt always happen that way in busy cockpit) then after your plane is below current set ap altitude dial set MA. Plane (in my case) will then start climbing! 

I don't think I've had any other plane do this except very basic default planes. Once on glide path ap should IGNORE any change to altitude dial unless you cancel APPR. Most poh texts read dial ma after gs capture in the checklists for that reason. 

10 minutes ago, sloppysmusic said:

Exactly. The whole point of the turbocharger is to NOT to have to do ANY mixture fiddling until AFTER critical altitude. The fact the airplane is less likely to die on you if you do fiddle below CA is simple evidence of a major flaw in the modeling. You should never need to level off DURING a climb or descent to fine tune the mix for safety. 

My logic behind leaning did not have anything to do with critical altitude. Although the turbocharged piston CAN be flown up to CA without any leaning, I thought (perhaps erroneously) that it would make sense to lean for best power or best fuel economy - well before CA. 

Of course, when approaching CA, it would make sense to start leaning, to prevent loss of power. 

This is also a reply to @martinboehme 😉 

Edited May 20, 20242 yr by Cpt_Piett

16 minutes ago, sloppysmusic said:

The fact the airplane is less likely to die on you if you do fiddle below CA is simple evidence of a major flaw in the modeling. You should never need to level off DURING a climb or descent to fine tune the mix for safety. 

I've been paying more attention to this over the weekend, and I have seen zero evidence of this. The engine's power remains at maximum through 20,000 ft and beyond, with no chance of quitting at full throttle. In the nicest way possible, can you just lean the mixtures above the critical altitude and mind your throttles on the way down like the rest of us are seemingly doing? On the descent, air pressure will always be increasing so once you've set descent power engine performance should only increase from there.

There's just no reason to be afraid of this aircraft dying on you, in my experience. I haven't had it happen once without trying to make it happen because of this thread.