29 Mar 2024, 21:36 [ UTC - 5; DST ]
|
Username Protected |
Message |
Username Protected
|
Post subject: Re: MU2 Pre-buy speed 36 ktas below book Posted: 27 Dec 2021, 13:13 |
|
|
|
|
|
Joined: 11/08/12 Posts: 6239 Post Likes: +3738 Location: San Carlos, CA - KHWD
Aircraft: Piaggio Avanti
|
|
Username Protected wrote: … keep asking for actual info on flight manual veracity, which should be of general interest to everybody. My MU2B-40 Solitaire (-10 engines) makes very close to book numbers in cruise.
_________________ -Jon C.
|
|
Top |
|
Username Protected
|
Post subject: Re: MU2 Pre-buy speed 36 ktas below book Posted: 27 Dec 2021, 13:42 |
|
|
|
|
|
Joined: 11/25/16 Posts: 1819 Post Likes: +1382 Location: 2IS
Aircraft: C501
|
|
Username Protected wrote: That would depend on how high you are, and how much energy was lost, turning onto each leg, but if IAS has not changed in 60 seconds, it is probably not going to change much more. A turbine airplane that is at a very high altitude, high angle of attack, and lower indicated airspeed, is going to take much longer to stabilize than a B-55 at low angle of attack. In my case, an Aerostar and I'll probably do this at 10K, 15K and 20K. So 10 mins per leg would be more than sufficient?
|
|
Top |
|
Username Protected
|
Post subject: Re: MU2 Pre-buy speed 36 ktas below book Posted: 27 Dec 2021, 13:45 |
|
|
|
|
|
Joined: 04/02/18 Posts: 270 Post Likes: +134 Location: 20GA
Aircraft: RV-4
|
|
Username Protected wrote: That would depend on how high you are, and how much energy was lost, turning onto each leg, but if IAS has not changed in 60 seconds, it is probably not going to change much more. A turbine airplane that is at a very high altitude, high angle of attack, and lower indicated airspeed, is going to take much longer to stabilize than a B-55 at low angle of attack. In my case, an Aerostar and I'll probably do this at 10K, 15K and 20K. So 10 mins per leg would be more than sufficient?
It shouldn’t take anywhere near that long, each leg only needs to be held long enough for airspeed to stabilize. Once it does, write down GS and track, then turn to the next heading.
|
|
Top |
|
Username Protected
|
Post subject: Re: MU2 Pre-buy speed 36 ktas below book Posted: 27 Dec 2021, 13:51 |
|
|
|
|
Joined: 01/12/10 Posts: 397 Post Likes: +768 Location: Dallas, Texas
Aircraft: Piaggio P180, TTx
|
|
Username Protected wrote: Folks, I recently test-flew an MU-2K in very good shape and got 253 ktas at 25,000' vs 289 ktas flight manual prediction for identical weight/alt/temp at max cruise power.
I know there are a thousand pitfalls in measuring performance and I promise to come back and report when, as I expect, this data point is confirmed/refuted. But for now, rather than present all the data for in-depth analysis, I'd really like to know from MU-2-experienced persons: do MU2s generally fly on book speeds, or a few knots slow, or all over the place..... or even if no one ever really checks them against the flight manual, so we don't really know.
For reference -- I hear that Beech flight manuals are pretty accurate, and I can verify that a Mooney 252 that I owned flew dead on book, within 1 knot and 0.1 gph.
Thanks in advance --
Charley Brown Charley I had a K model withOUT the original engines (NOT the -10 engines) and it consistently did 280 Knots on 85GPH fuel flow. Something is very wrong or a gear door is sticking out lol...
|
|
Top |
|
Username Protected
|
Post subject: Re: MU2 Pre-buy speed 36 ktas below book Posted: 27 Dec 2021, 14:37 |
|
|
|
|
Joined: 10/05/09 Posts: 286 Post Likes: +130 Location: Portland, Oregon
Aircraft: MU-2F
|
|
It would be good to know how heavy you were as well. My plane (F model with -1 engines) will be at ~250KTAS when leveling off at FL250 after taking off with full fuel, but will speed up to ~260KTAS as the tip tanks empty. Best speed I have seen so far is 272KTAS at FL240 at -32C. We were using just over 60gph at the time and EGTs were just below the bottom of the yellow arc.
|
|
Top |
|
Username Protected
|
Post subject: Re: MU2 Pre-buy speed 36 ktas below book Posted: 27 Dec 2021, 15:39 |
|
|
|
|
Joined: 05/05/09 Posts: 4946 Post Likes: +4785
Aircraft: G44, C501, C55, R66
|
|
Username Protected wrote: It would be good to know how heavy you were as well. My plane (F model with -1 engines) will be at ~250KTAS when leveling off at FL250 after taking off with full fuel, but will speed up to ~260KTAS as the tip tanks empty. Best speed I have seen so far is 272KTAS at FL240 at -32C. We were using just over 60gph at the time and EGTs were just below the bottom of the yellow arc. My F wouldn't go to FL240 will full gas and 3 people but I did see 275kts TAS once out west int he winter at 220. Really an amazing airplane.
|
|
Top |
|
Username Protected
|
Post subject: Re: MU2 Pre-buy speed 36 ktas below book Posted: 27 Dec 2021, 15:40 |
|
|
|
|
Joined: 08/24/13 Posts: 8410 Post Likes: +3662 Company: Aviation Tools / CCX Location: KSMQ New Jersey
Aircraft: TBM700C2
|
|
Username Protected wrote: On a normal IFR Pitot Static check do they run the Airspeed up to verify accuracy?
No, it is not part of the 2 year check. But you do need to connect to the pitot lines when running up the altitude, so most techs will look at it and _should_ let you know if it is off much. Some OEM airframe inspections include an airspeed check.
|
|
Top |
|
Username Protected
|
Post subject: Re: MU2 Pre-buy speed 36 ktas below book Posted: 27 Dec 2021, 18:12 |
|
|
|
|
|
Joined: 03/17/08 Posts: 6053 Post Likes: +12366 Location: KMCW
Aircraft: B55 PII,F-1,L-2,OTW,
|
|
Username Protected wrote: On a normal IFR Pitot Static check do they run the Airspeed up to verify accuracy? I had them do it on my new Garmin panel just to make sure everything was reading right.
I guess I recall them doing it on our M-model, but we had the A/P disconnect plumbing in the pitot lines and they didn't match left to right. A static check confirms the indicator and the tubing, but the installation error can be significant and it varies with AOA, hence the difference between IAS and CAS. A pitot tube under the wing is in a higher pressure area. To be accurate the rule of thumb is that the pitot tube needs to be 1/2 the wing chord distance in front of the leading edge to get ahead of the pressure wave in front of the wing.
_________________ Tailwinds, Doug Rozendaal MCW Be Nice, Kind, I don't care, be something, just don't be a jerk ;-)
|
|
Top |
|
Username Protected
|
Post subject: Re: MU2 Pre-buy speed 36 ktas below book Posted: 27 Dec 2021, 19:58 |
|
|
|
|
Joined: 08/01/11 Posts: 6692 Post Likes: +4355 Location: In between the opioid and marijuana epidemics
Aircraft: 182, A36TC
|
|
We’re the flaps now r gear down?
_________________ Fly High,
Ryan Holt CFI
"Paranoia and PTSD are requirements not diseases"
|
|
Top |
|
Username Protected
|
Post subject: Re: MU2 Pre-buy speed 36 ktas below book Posted: 27 Dec 2021, 20:41 |
|
|
|
|
Joined: 03/22/14 Posts: 103 Post Likes: +65 Location: KMYF/ Kamiah, ID
Aircraft: C525, AC90
|
|
Username Protected wrote: On a normal IFR Pitot Static check do they run the Airspeed up to verify accuracy?
No, it is not part of the 2 year check. But you do need to connect to the pitot lines when running up the altitude, so most techs will look at it and _should_ let you know if it is off much. Some OEM airframe inspections include an airspeed check.
My airspeed check was not done until I requested it. When I added the GI275 backup I found the g600 was off. The backup analog, co pilot, and GI275 all matched. The G600 was off. (3 percent slow). Twin turbine AC90. There is no way to adjust the G600 airspeed, so the air-data computer would need to be replaced or debugged. If the MU2 has a G600, that’s just another variable to check.
_________________ MEL, Comm. Instr. C525(S) type
|
|
Top |
|
Username Protected
|
Post subject: Re: MU2 Pre-buy speed 36 ktas below book Posted: 27 Dec 2021, 20:46 |
|
|
|
|
Joined: 10/07/18 Posts: 2650 Post Likes: +1764 Location: Columbus, Ohio
Aircraft: Baron 58, Lear 35
|
|
Username Protected wrote: To be accurate the rule of thumb is that the pitot tube needs to be 1/2 the wing chord distance in front of the leading edge to get ahead of the pressure wave in front of the wing. The MU2s I’ve worked on have the pitot tubes on the side of the fuselage, about even with, or slightly forward of, the lower edge of the windshield.
|
|
Top |
|
Username Protected
|
Post subject: Re: MU2 Pre-buy speed 36 ktas below book Posted: 28 Dec 2021, 00:56 |
|
|
|
|
Joined: 01/17/21 Posts: 87 Post Likes: +42
Aircraft: C550
|
|
Had a K model with -6 engine’s & consistently got 270 to 275 true in the low 20’s .
|
|
Top |
|
Username Protected
|
Post subject: Re: MU2 Pre-buy speed 36 ktas below book Posted: 28 Dec 2021, 02:42 |
|
|
|
|
|
Joined: 06/02/15 Posts: 2691 Post Likes: +1690 Location: Fresno, CA (KFAT)
Aircraft: T210M
|
|
Username Protected wrote: When you retest.
1) load it heavy as possible and try whatever takeoff config gives you the longest ground roll
2) do speed runs at low, Middle and high altitudes
3) do a vy climb and note results
I suspect the end result will be a borescope but unless it’s instrumentation the possibilities are power and drag. Above might help determine which If the engine(s) are the problem, would TQ, ITT, FF, and Ng not make book?
_________________ Tom DeWitt Previous: TBM850/T210M/C182P APS 2004
|
|
Top |
|
|
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot post attachments in this forum
|
Terms of Service | Forum FAQ | Contact Us
BeechTalk, LLC is the quintessential Beechcraft Owners & Pilots Group providing a
forum for the discussion of technical, practical, and entertaining issues relating to all Beech aircraft. These include
the Bonanza (both V-tail and straight-tail models), Baron, Debonair, Duke, Twin Bonanza, King Air, Sierra, Skipper, Sport, Sundowner,
Musketeer, Travel Air, Starship, Queen Air, BeechJet, and Premier lines of airplanes, turboprops, and turbojets.
BeechTalk, LLC is not affiliated or endorsed by the Beechcraft Corporation, its subsidiaries, or affiliates.
Beechcraft™, King Air™, and Travel Air™ are the registered trademarks of the Beechcraft Corporation.
Copyright© BeechTalk, LLC 2007-2024
|
|
|
|