banner
banner

28 Mar 2024, 09:18 [ UTC - 5; DST ]


Concorde Battery (banner)



Reply to topic  [ 1769 posts ]  Go to page Previous  1 ... 98, 99, 100, 101, 102, 103, 104 ... 118  Next
Username Protected Message
 Post subject: Re: Citation 501sp
PostPosted: 31 Jul 2021, 20:14 
Offline


User avatar
 Profile




Joined: 02/15/21
Posts: 2512
Post Likes: +1240
Username Protected wrote:
I understand the relatively recent emphasis on AOA's by FAA. I went through Flight Safety for Lears and Citations, but a long time ago, and AOA's were not in the training programs.
.
I operated a Lear 24 from a 3,000 dirt strip, and never felt that an AOA was any help. None of the Douglas and Boeings I flew had AOA's.

And God forbid that anybody should need to know what the best glide AOA is in a multi-engine turbojet. ;)

Hi Paul,

Trying to minimize what I have to store in my brain was my whole reason for this exercise. The manual says best glide is 120KIAS @8,500lbs + 3KIAS for every 500lbs over 8,500. If I am be-bopping along in cruise, and both engines quit, I like the idea of only having to look at the AoA gauge and pitch for a single value, regardless of current weight. It saves me from knowing my weight at all times (though maybe i should be constantly calculating this while flying?) and having to calculated a glide speed during a very stressful time.

I also like the heads-up AoA indicator that is on the dash. It really helps me keep my head out of the cockpit on short final.

Chris, since you already have a 501, maybe you can go out and test the AOA gauge. If it's safe to do so, perform a flaps-up, power-off glide at 120KIAS @8,500lbs + 3KIAS for every 500lbs over 8,500 and see what the AOA reads.

Also make a note of the TAS (or at least the altitude and temp to later derive TAS) and vertical speed so we'll know the glide angle.

If the AOA is not reading 0.6, then fly at 0.6 and take new TAS and vertical speed readings and see if it's better or worse than flying the recommended airspeed.
_________________
Aviate, Navigate, Communicate, Administrate, Litigate.


Top

 Post subject: Re: Citation 501sp
PostPosted: 31 Jul 2021, 20:33 
Offline


User avatar
 Profile




Joined: 03/28/17
Posts: 6624
Post Likes: +7925
Location: N. California
Aircraft: C-182
Username Protected wrote:
I understand the relatively recent emphasis on AOA's by FAA. I went through Flight Safety for Lears and Citations, but a long time ago, and AOA's were not in the training programs.
.
I operated a Lear 24 from a 3,000 dirt strip, and never felt that an AOA was any help. None of the Douglas and Boeings I flew had AOA's.

And God forbid that anybody should need to know what the best glide AOA is in a multi-engine turbojet. ;)

Hi Paul,

Trying to minimize what I have to store in my brain was my whole reason for this exercise. The manual says best glide is 120KIAS @8,500lbs + 3KIAS for every 500lbs over 8,500. If I am be-bopping along in cruise, and both engines quit, I like the idea of only having to look at the AoA gauge and pitch for a single value, regardless of current weight. It saves me from knowing my weight at all times (though maybe i should be constantly calculating this while flying?) and having to calculated a glide speed during a very stressful time.

I also like the heads-up AoA indicator that is on the dash. It really helps me keep my head out of the cockpit on short final.


I understand what your objective is Chris, but there is quite a difference of opinion between you and Mike, and even a question of the manual's accuracy. Then we have to have confidence that the AOA is in calibration throughout the flap range..

To achieve a particular maneuvering speed, it can be keyed to an additive to basic ref speed. For example, let's say the basic ref for your plane. meaning the plane's approach speed with two crew onboard is 100 knots and one knot is added for each additional 200 pounds onboard, fuel or pax, usually just adding 1 knot per pax in light jets. This is done all the time without getting out a speed chart or relying on an AOA..

So to calculate your final approach speed ref with just crew and fuel onboard, you look at your fuel totalizer; i.e. it says 2000 pounds of fuel; 1 knot per 200 pounds means adding 10 knots knots to your basic ref, or 110 knot approach speed. Best glide speed is an additive to ref , so now that you have your ref, add the additive and bug the speed. Just keep in mind that the basic ref speed is based on landing flaps, and the additive for best glide is based on that speed, but flown with flaps up. It's not as much of a mental gymnastic exercise as it sounds, probably 5 seconds of mental calculation.

In the end, if you have all engines flame out, you are going to run the memory items, then get out the Quick Reference Handbook for that, and it should have a speed chart, and many planes keep a running gross weight making it a simple exercise but without a running gross weight, you get your speed as calculated above knowing the best glide additive..

Top

 Post subject: Re: Citation 501sp
PostPosted: 31 Jul 2021, 21:49 
Offline

 Profile




Joined: 12/30/18
Posts: 5
Post Likes: +4
Aircraft: b58
Ya, not a 501 but real deal & lived to talk about it. Worth a few minutes.

https://youtu.be/sKxgne1J2pU


Top

 Post subject: Re: Citation 501sp
PostPosted: 31 Jul 2021, 23:21 
Offline


 Profile




Joined: 11/06/20
Posts: 1276
Post Likes: +1270
Location: Tulsa, OK - KRVS
Aircraft: C501SP
Username Protected wrote:
I understand what your objective is Chris, but there is quite a difference of opinion between you and Mike, and even a question of the manual's accuracy. Then we have to have confidence that the AOA is in calibration throughout the flap range..

Hi Paul,

Thank you for insight. But just to be clear, the disagreement is between Ian and Mike. I read the Operating Manual that mentioned .6 (best endurance) and .35 (best range), and was asking BT braintrust for their thoughts.

Ian,

Yes, actual testing would certainly put this to bed. I have a trip to NorCal on 13 August. We could test this when cleared to descend. Will have the family aboard so I don't want to do anything crazy, but it shouldn't be too radical.... I will talk to my instructor/mentor to see if he's game.


Top

 Post subject: Re: Citation 501sp
PostPosted: 01 Aug 2021, 00:32 
Offline


 WWW  Profile




Joined: 12/03/14
Posts: 19252
Post Likes: +23612
Company: Ciholas, Inc
Location: KEHR
Aircraft: C560V
Username Protected wrote:
Yes, actual testing would certainly put this to bed. I have a trip to NorCal on 13 August. We could test this when cleared to descend. Will have the family aboard so I don't want to do anything crazy, but it shouldn't be too radical.... I will talk to my instructor/mentor to see if he's game.

Set some low power setting and try 0.35-0.40 and see what airspeed and descent rate you get in steady state, then try 0.60 and see what airspeed and descent rate you get.

I predict you will get lowest descent rate at 0.6 and best glide range at 0.40 or so.

0.6 might be a bit uncomfortable in a regular descent as it is quite slow, even flaps up, so all this may have to be done on a non trip flight.

Mike C.

_________________
Email mikec (at) ciholas.com


Top

 Post subject: Re: Citation 501sp
PostPosted: 01 Aug 2021, 11:09 
Offline


User avatar
 Profile




Joined: 03/28/17
Posts: 6624
Post Likes: +7925
Location: N. California
Aircraft: C-182
Username Protected wrote:
I understand what your objective is Chris, but there is quite a difference of opinion between you and Mike, and even a question of the manual's accuracy. Then we have to have confidence that the AOA is in calibration throughout the flap range..

Hi Paul,

Thank you for insight. But just to be clear, the disagreement is between Ian and Mike. I read the Operating Manual that mentioned .6 (best endurance) and .35 (best range), and was asking BT braintrust for their thoughts.

Ian,

Yes, actual testing would certainly put this to bed. I have a trip to NorCal on 13 August. We could test this when cleared to descend. Will have the family aboard so I don't want to do anything crazy, but it shouldn't be too radical.... I will talk to my instructor/mentor to see if he's game.


Sorry for the names mixup Chris.

Testing the AOA vs airspeed in a best glide test won't be completely accurate because of the residual thrust of the engines at idle, but I don't know how close it might be. I don't remember if the JT-15D has a flight idle and a ground idle.

Chances of having a dual engine failure are slim to begin with, and then if it happens there may be an airport close enough where max distance isn't required.

When considering a dual engine failure, maybe more important than knowing the max range AOA or airspeed, is knowing the effects on systems. What did you lose, what do you have left, what are the landing implications. That's where knowing the systems is important and worth putting in the study time..

Knowing the re-light envelope is important too to try to get them back if they meet the windmilling parameters.

Top

 Post subject: Re: Citation 501sp
PostPosted: 01 Aug 2021, 16:30 
Offline


User avatar
 Profile




Joined: 02/15/21
Posts: 2512
Post Likes: +1240
Username Protected wrote:
Sorry for the names mixup Chris.

Testing the AOA vs airspeed in a best glide test won't be completely accurate because of the residual thrust of the engines at idle, but I don't know how close it might be. I don't remember if the JT-15D has a flight idle and a ground idle.

Chances of having a dual engine failure are slim to begin with, and then if it happens there may be an airport close enough where max distance isn't required.

When considering a dual engine failure, maybe more important than knowing the max range AOA or airspeed, is knowing the effects on systems. What did you lose, what do you have left, what are the landing implications. That's where knowing the systems is important and worth putting in the study time..

Knowing the re-light envelope is important too to try to get them back if they meet the windmilling parameters.

Good point, Paul, but perhaps a zero thrust condition could be extrapolated as follows:

Fly at 10% thrust and 0.6 AOA and note airspeed and vertical speed. Then fly at 20% thrust and 0.6 AOA and note AS and VS. From this the airspeed and vertical speed at 0.6 AOA and zero thrust can be estimated.

_________________
Aviate, Navigate, Communicate, Administrate, Litigate.


Top

 Post subject: Re: Citation 501sp
PostPosted: 01 Aug 2021, 18:10 
Offline


 Profile




Joined: 04/24/18
Posts: 727
Post Likes: +340
Location: NYC
Aircraft: ISP Eagle II SR22 g2
Username Protected wrote:
Sorry for the names mixup Chris.

Testing the AOA vs airspeed in a best glide test won't be completely accurate because of the residual thrust of the engines at idle, but I don't know how close it might be. I don't remember if the JT-15D has a flight idle and a ground idle.

Chances of having a dual engine failure are slim to begin with, and then if it happens there may be an airport close enough where max distance isn't required.

When considering a dual engine failure, maybe more important than knowing the max range AOA or airspeed, is knowing the effects on systems. What did you lose, what do you have left, what are the landing implications. That's where knowing the systems is important and worth putting in the study time..

Knowing the re-light envelope is important too to try to get them back if they meet the windmilling parameters.

Good point, Paul, but perhaps a zero thrust condition could be extrapolated as follows:

Fly at 10% thrust and 0.6 AOA and note airspeed and vertical speed. Then fly at 20% thrust and 0.6 AOA and note AS and VS. From this the airspeed and vertical speed at 0.6 AOA and zero thrust can be estimated.


How would you calculate % of thrust?

Top

 Post subject: Re: Citation 501sp
PostPosted: 01 Aug 2021, 18:23 
Offline


User avatar
 Profile




Joined: 02/15/21
Posts: 2512
Post Likes: +1240
Username Protected wrote:
Good point, Paul, but perhaps a zero thrust condition could be extrapolated as follows:

Fly at 10% thrust and 0.6 AOA and note airspeed and vertical speed. Then fly at 20% thrust and 0.6 AOA and note AS and VS. From this the airspeed and vertical speed at 0.6 AOA and zero thrust can be estimated.


How would you calculate % of thrust?

Hi Israel,

We can probably find a fuel flow or N1 chart somewhere.

If my dad were still around, he'd probably rig up something with a kitchen scale.

Even though residual thrust will affect glide angle, there shouldn't be much change in airspeed as thrust varies between zero and residual thrust at a constant angle of attack in unaccelerated flight.

So we should easily be able to know the airspeed at zero thrust at 0.6 AOA as it should be pretty much the same as the airspeed at residual thrust at 0.6 AOA.
_________________
Aviate, Navigate, Communicate, Administrate, Litigate.


Top

 Post subject: Re: Citation 501sp
PostPosted: 01 Aug 2021, 20:26 
Offline


User avatar
 Profile




Joined: 03/28/17
Posts: 6624
Post Likes: +7925
Location: N. California
Aircraft: C-182
Of course if there was a dual engine flame out in the flight levels, an emergency descent would likely be the procedure, rather than best glide. ;)


Top

 Post subject: Re: Citation 501sp
PostPosted: 01 Aug 2021, 21:15 
Online


User avatar
 Profile




Joined: 06/02/15
Posts: 2688
Post Likes: +1687
Location: Fresno, CA (KFAT)
Aircraft: T210M
Username Protected wrote:
Of course if there was a dual engine flame out in the flight levels, an emergency descent would likely be the procedure, rather than best glide. ;)


Yup. That’s the biggest flaw in the ForeFlight and other displays with a “glide range” ring.

_________________
Tom DeWitt
Previous: TBM850/T210M/C182P
APS 2004


Top

 Post subject: Re: Citation 501sp
PostPosted: 01 Aug 2021, 22:09 
Offline


 Profile




Joined: 11/06/20
Posts: 1276
Post Likes: +1270
Location: Tulsa, OK - KRVS
Aircraft: C501SP
Username Protected wrote:
Testing the AOA vs airspeed in a best glide test won't be completely accurate because of the residual thrust of the engines at idle, but I don't know how close it might be. I don't remember if the JT-15D has a flight idle and a ground idle.

Chances of having a dual engine failure are slim to begin with, and then if it happens there may be an airport close enough where max distance isn't required.

When considering a dual engine failure, maybe more important than knowing the max range AOA or airspeed, is knowing the effects on systems. What did you lose, what do you have left, what are the landing implications. That's where knowing the systems is important and worth putting in the study time..

Knowing the re-light envelope is important too to try to get them back if they meet the windmilling parameters.

But if we're just comparing .6 vs .35 on glide distance, why do we care about residual thrust as long as it is the same in both tests? Someone could just go to 17,500, throttle to idle, pitch for .6, record parameters (TAS, VS, etc). Descend for a few thousand feet, then go back to 17,500, pointed the same way so winds should be the same, and do it again at .35. Then just compare the two.

But yes, knowing all of those other systems things like losing hydraulics (gear, speedbrakes), electrical (flaps), bleed air for pressurization, etc are definitely part of it. I have read through the Operating Manual twice now. Several more to go before type rating in mid-October.


Top

 Post subject: Re: Citation 501sp
PostPosted: 01 Aug 2021, 22:29 
Offline


User avatar
 Profile




Joined: 02/15/21
Posts: 2512
Post Likes: +1240
Username Protected wrote:
Testing the AOA vs airspeed in a best glide test won't be completely accurate because of the residual thrust of the engines at idle, but I don't know how close it might be. I don't remember if the JT-15D has a flight idle and a ground idle.

Chances of having a dual engine failure are slim to begin with, and then if it happens there may be an airport close enough where max distance isn't required.

When considering a dual engine failure, maybe more important than knowing the max range AOA or airspeed, is knowing the effects on systems. What did you lose, what do you have left, what are the landing implications. That's where knowing the systems is important and worth putting in the study time..

Knowing the re-light envelope is important too to try to get them back if they meet the windmilling parameters.

But if we're just comparing .6 vs .35 on glide distance, why do we care about residual thrust as long as it is the same in both tests? Someone could just go to 17,500, throttle to idle, pitch for .6, record parameters (TAS, VS, etc). Descend for a few thousand feet, then go back to 17,500, pointed the same way so winds should be the same, and do it again at .35. Then just compare the two.

But yes, knowing all of those other systems things like losing hydraulics (gear, speedbrakes), electrical (flaps), bleed air for pressurization, etc are definitely part of it. I have read through the Operating Manual twice now. Several more to go before type rating in mid-October.

Yes, that's probably correct that the residual thrust is not going to greatly bias the results as far as which angle of attack gives a better glide; it's just that the actual glide ratios will be a bit too optimistic in both cases.
_________________
Aviate, Navigate, Communicate, Administrate, Litigate.


Top

 Post subject: Re: Citation 501sp
PostPosted: 01 Aug 2021, 23:25 
Offline


User avatar
 Profile




Joined: 03/28/17
Posts: 6624
Post Likes: +7925
Location: N. California
Aircraft: C-182
As near as I can tell the debate with Mike C. and Ian is which AOA is best glide . .6 or .35.

I'm going out on a limb and saying .35 is best glide, and .6 is the AOA for approach. ;)

This would conclude my studying of the issue so I could fry my brain trying to understand something else. :D

From a Citation study guide:


Please login or Register for a free account via the link in the red bar above to download files.


Top

 Post subject: Re: Citation 501sp
PostPosted: 01 Aug 2021, 23:37 
Offline


User avatar
 Profile




Joined: 02/15/21
Posts: 2512
Post Likes: +1240
Username Protected wrote:
As near as I can tell the debate with Mike C. and Ian is which AOA is best glide . .6 or .35.

Mike is saying best glide is at about 0.40.

And I still maintain 0.6 is correct for approach, with flaps in approach position.

_________________
Aviate, Navigate, Communicate, Administrate, Litigate.


Top

Display posts from previous:  Sort by  
Reply to topic  [ 1769 posts ]  Go to page Previous  1 ... 98, 99, 100, 101, 102, 103, 104 ... 118  Next




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

Jump to:  

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

.gallagher_85x50.jpg.
.tempest.jpg.
.concorde.jpg.
.SCA.jpg.
.avfab-85x50-2018-12-04.png.
.pdi-85x50.jpg.
.Genesys_85x50.jpg.
.daytona.jpg.
.sierratrax-85x50.png.
.aircraftassociates-85x50.png.
.midwest2.jpg.
.dbm.jpg.
.stanmusikame-85x50.jpg.
.traceaviation-85x150.png.
.aeroled-85x50-2022-12-06.jpg.
.airmart-85x150.png.
.chairmanaviation-85x50.jpg.
.CiESVer2.jpg.
.kingairnation-85x50.png.
.jandsaviation-85x50.jpg.
.bullardaviation-85x50-2.jpg.
.ei-85x150.jpg.
.blackwell-85x50.png.
.pure-medical-85x150.png.
.Wentworth_85x100.JPG.
.ssv-85x50-2023-12-17.jpg.
.aviationdesigndouble.jpg.
.avionwealth-85x50.png.
.bpt-85x50-2019-07-27.jpg.
.one-mile-up-85x100.png.
.temple-85x100-2015-02-23.jpg.
.lucysaviation-85x50.png.
.tat-85x100.png.
.AAI.jpg.
.cav-85x50.jpg.
.camguard.jpg.
.Wingman 85x50.png.
.headsetsetc_Small_85x50.jpg.
.kingairacademy-85x100.png.
.Latitude.jpg.
.wilco-85x100.png.
.blackhawk-85x100-2019-09-25.jpg.
.Marsh.jpg.
.Rocky-Mountain-Turbine-85x100.jpg.
.geebee-85x50.jpg.
.saint-85x50.jpg.
.boomerang-85x50-2023-12-17.png.
.kadex-85x50.jpg.
.jetacq-85x50.jpg.
.aircraftferry-85x50.jpg.
.wat-85x50.jpg.
.shortnnumbers-85x100.png.
.MountainAirframe.jpg.
.Foreflight_85x50_color.png.
.centex-85x50.jpg.
.planelogix-85x100-2015-04-15.jpg.
.ABS-85x100.jpg.