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Is It Possible To "land Using Only The Knobs"?  
User currently offlineMrSkyGuy From United States of America, joined Aug 2008, 1214 posts, RR: 3
Posted (4 years 8 months 3 weeks 1 day 23 hours ago) and read 4543 times:

Please read the entirety of my OP below before replying to the question directly in the subject.

The question is slightly rhetorical, because I'm pretty certain it's possible.. however unlikely. But consider the hypothetical first. If by some bizarre chain of events the aircraft's physical flight controls were disabled [in a medium to large Boeing/Airbus aircraft] including the rudder pedals, yoke and throttles but with controllable flight being capable through the "knobs" [the autopilot interface controls = hdg knob, alt knob, pitch knob and AT only], would the flight crew be capable of flying the aircraft to a safe landing? (and for the purpose of the mental exercise, exclude any auto-land capabilities including LOC/GS or APP) Consider the flare and the attitude of the aircraft crossing the numbers and the gentle nature of flying the aircraft via the HDG bug/knob vs. the more responsive manual controls.

What brought this to mind was the events which surrounded Phillipine Airlines Flight 434, where the bomb exploded and disabled the flight controls. Control was initially maintained via the autopilot, but the autopilot's ability to control the aircraft eventually failed and the crew resorted to using variable thrust to control/land the aircraft (in a superb feat of airmanship). What if the bomb had disabled only the physical flight controls, leaving the AP knobs? Or would they have resorted to variable thrust? Perhaps both?

[Edited 2010-02-05 21:29:51]


"The strength of the turbulence is directly proportional to the temperature of your coffee." -- Gunter's 2nd Law of Air
22 replies: All unread, jump to last
 
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 1, posted (4 years 8 months 3 weeks 1 day 21 hours ago) and read 4405 times:

Quoting MrSkyGuy (Thread starter):
If by some bizarre chain of events the aircraft's physical flight controls were disabled [in a medium to large Boeing/Airbus aircraft] including the rudder pedals, yoke and throttles but with controllable flight being capable through the "knobs" [the autopilot interface controls = hdg knob, alt knob, pitch knob and AT only], would the flight crew be capable of flying the aircraft to a safe landing?

Yes. You'd basically fly the equivalent of a visual approach using the AP controls. I've done this in sims before. You need to set up really far out (an extremely stabilized approach) but, once you do, you just fly it all the way on to the ground.

Quoting MrSkyGuy (Thread starter):
What if the bomb had disabled only the physical flight controls, leaving the AP knobs?

There's a terminology problem here...the flight controls are the moveable surfaces on the wings and tail. If you disable those, the AP doesn't work either. You're talking about disabling the pilot inceptors (the input devices).

Tom.


User currently offlineFLY2HMO From , joined Dec 1969, posts, RR:
Reply 2, posted (4 years 8 months 3 weeks 1 day 21 hours ago) and read 4354 times:

Quoting MrSkyGuy (Thread starter):
Consider the flare and the attitude of the aircraft crossing the numbers and the gentle nature of flying the aircraft via the HDG bug/knob vs. the more responsive manual controls.

The more gentle responses are not necessarily a good thing, specially at low speeds. You need a greater control input for a given motion at a slow speed vs a fast speed. The AP should compensate for it but it's still noticeable to an extent, depending on plane and AP system of course.


User currently offlinemcdu From United States of America, joined Apr 2005, 1474 posts, RR: 17
Reply 3, posted (4 years 8 months 3 weeks 1 day 21 hours ago) and read 4306 times:

You do realize the AP is manipulating the flight controls via servos. It manipulates the same control surfaces as the manual control surfaces as they yoke and rudder. Thus in your example of "frozen" controls the lack of manual input ability also equals the lack of AP input. The best example of this is UA 232 where all hydraulic power was lost. The aircraft was only left with steering via thrust inputs versus any control input. One of the biggest issues is the aircraft trimmed speed state. The speed for approach and landing is much higher than the speed for cruise. Aerodynamically, the aircraft will attempt to maintain its trimmed speed; ie it will nose down to chase the trimmed speed if power is reduced and it will nose up to chase the trimmed speed if power is reduced. This is called "phugoid". In the case of 232 the aircraft was at cruise trimmed speed. If you watch the video of 232 you will notice the nose drop as they near the runway. This was the result of the crew reducing the power in hopes of touching down. The phugoid caused the nose to drop and they had a bit of roll that resulted in the rolling crash.

If you lose manual controls you would lose the AP. Now if you removed the yokes from the flight deck and only had the AP controls? Then yes you could land the aircraft with AP. You would need to operate with a deft touch for the flare using V/S mode. My recommendation would be to configure early (gear down, final flap setting) have one pilot maintain lateral control with HDG Select and the other maintain Vertical control with VS. With emphasis on the VS mode to be a touchdown in the 100-200FPM range.


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 4, posted (4 years 8 months 3 weeks 1 day 9 hours ago) and read 3983 times:

Quoting mcdu (Reply 3):
The speed for approach and landing is much higher than the speed for cruise.

Other way around...cruise is higher than approach/landing.

Quoting mcdu (Reply 3):
This is called "phugoid".

Actually, no. Phugoid is a stable oscillatory pitch mode that occurs at constant thrust and constant trim (it's a lightly-damped trade between gravitational and kinetic energy). The same speed-seeking behavior that causes pitch-up/down with thrust changes is also responsible for phugoids, but the change due to thrust changes isn't the phugoid.

Quoting mcdu (Reply 3):
You would need to operate with a deft touch for the flare using V/S mode.

I wouldn't bother...just set up a really shallow glideslope and fly it all the way on to the runway.

Tom.


User currently offlinemcdu From United States of America, joined Apr 2005, 1474 posts, RR: 17
Reply 5, posted (4 years 8 months 3 weeks 1 day 7 hours ago) and read 3905 times:

Quoting tdscanuck (Reply 4):
Actually, no.

I disagree. But the basis of the original question is absurd. If you lose aileron and elevator control you lose A/P control.


Phugoid
A 'phugoid' (pronounced ) is an aircraft motion where the vehicle pitches up and climbs, and then pitches down and descends, accompanied by speeding up and slowing down as it goes 'uphill' and 'downhill.' This is one of the basic flight dynamics modes of an aircraft (others include short period, dutch roll, and spiral divergence).


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 6, posted (4 years 8 months 3 weeks 1 day 6 hours ago) and read 3895 times:

Quoting mcdu (Reply 5):
I disagree.

Fair enough, but the definition you posted agrees with what I said, not the pitch change due to thrust change. The basic flight dynamics modes all come out of a linearization of the complete equations of motion for the aircraft and that linearization is predicated on (among other things) constant thrust.

Quoting mcdu (Reply 5):
But the basis of the original question is absurd. If you lose aileron and elevator control you lose A/P control.

The wording wasn't good...the question was still OK. The OP is really asking if you can land the plane without the pilot inceptors (yoke and rudder pedals).

Tom.


User currently offlineMrSkyGuy From United States of America, joined Aug 2008, 1214 posts, RR: 3
Reply 7, posted (4 years 8 months 3 weeks 1 day 6 hours ago) and read 3862 times:

Quoting mcdu (Reply 5):
I disagree. But the basis of the original question is absurd. If you lose aileron and elevator control you lose A/P control.

Thanks for the delicate use of words.. it was, afterall, a hypothetical. I was asking you to consider the circumstances within the boundaries of the situation purely for the thought process of how control-ability would be maintained.. not to shoot my already swiss-cheese technical question full of more holes.

hy·po·thet·i·cal (hp-tht-kl) also hy·po·thet·ic (-thtk)
adj.
1. Of, relating to, or based on a hypothesis: a hypothetical situation. See Synonyms at theoretical.
2.
a. Suppositional; uncertain. See Synonyms at supposed.
b. Conditional; contingent.
n.
A hypothetical circumstance, condition, scenario, or situation: OK, let's consider this possibility thenjust as a hypothetical.

Quoting tdscanuck (Reply 6):
The OP is really asking if you can land the plane without the pilot inceptors (yoke and rudder pedals).

Precisely.



"The strength of the turbulence is directly proportional to the temperature of your coffee." -- Gunter's 2nd Law of Air
User currently offlinealwaysontherun From Netherlands Antilles, joined Jan 2010, 464 posts, RR: 0
Reply 8, posted (4 years 8 months 3 weeks 1 day 6 hours ago) and read 3855 times:

I may be off topic here, but I believe there is a system that was designed to land automatically without any hydraulics, just using difference thrust levels for rolling the plane, steering the plane and obviously controlling flight level.
A little bit like in the hypothetical situation posted by the OP, the type that could ruin your day.

I could be wrong here, but I saw it done in a simulator (on TV,jejeje!), and this system was developed after the Sioux City DC-10 crash, correct?

Please correct me, but I am under the understanding that this system is not installed on any commercial airliner, because of cost$$$ and the extreme unlikeliness of this type of distress.

Anyone care to develop this system with "facts" perhaps?

### "I am always on the Run"###



"Failure is not an option, it comes standard in any Windows product" - an anonymous MAC owner.
User currently offlinecobra27 From Slovenia, joined May 2001, 1020 posts, RR: 0
Reply 9, posted (4 years 8 months 3 weeks 1 day 6 hours ago) and read 3850 times:

I tried autoland on Microsoft simualtor with knobs only. it worked with 100 ft/min descent rate in the flare.
And as far as i know airplane can land with that 100 ft descent rate, but its not to good for them


User currently offlineFLY2HMO From , joined Dec 1969, posts, RR:
Reply 10, posted (4 years 8 months 3 weeks 1 day 5 hours ago) and read 3814 times:

Quoting cobra27 (Reply 9):
.
And as far as i know airplane can land with that 100 ft descent rate, but its not to good for them

100fpm isn't too bad, not for larger planes at least. IIRC, depending on plane of course, stuff won't break until over 1000fpm, but don't quote me on that. The engineers here will know better.

Quoting alwaysontherun (Reply 8):
Anyone care to develop this system with "facts" perhaps?
http://www.nasa.gov/centers/dryden/news/FactSheets/FS-076-DFRC.html


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 11, posted (4 years 8 months 3 weeks 1 day 4 hours ago) and read 3781 times:

Quoting alwaysontherun (Reply 8):
Please correct me, but I am under the understanding that this system is not installed on any commercial airliner, because of cost$$$ and the extreme unlikeliness of this type of distress.

It's safer and easier to put that engineering effort into making sure you never end up in that situation. Also, with the heavy preponderance of twins now, it's that much more difficult to implement good pitch control using thrust only.

Quoting FLY2HMO (Reply 10):
100fpm isn't too bad, not for larger planes at least. IIRC, depending on plane of course, stuff won't break until over 1000fpm, but don't quote me on that. The engineers here will know better.

It depends on the aircraft; specifically on the length of the oleo compression. What actually hurts the airplane is acceleration (g's). You need to get from whatever your descent rate is at touchdown to 0 fpm within the vertical limit of the oleo. A very large strut with a very large stroke can absorb a higher descent rate at a constant acceleration than a short stroke strut.

Tom.


User currently offlinebri2k1 From United States of America, joined Dec 2004, 988 posts, RR: 4
Reply 12, posted (4 years 8 months 3 weeks 1 day 3 hours ago) and read 3764 times:

It's not that absurd to me. What do you think UAVs are? The autopilots on normal pilot-controlled aircraft aren't designed to produce the rate of control surface change that would be required for equivalent performance and safe flight in all flight regimes, but obviously with a stabilized approach and an autoland, there is no more (possibly even less) danger than with pilots flying. Some UAVs are controlled by pilots manipulating controls on the ground that translate to control surface movements on the aircraft, but others are controlled by pre-programmed flight plans, somewhat like what you might be able to input using an FMS. I don't consider it too far-fetched.


Position and hold
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 13, posted (4 years 8 months 3 weeks 1 day ago) and read 3701 times:

Quoting bri2k1 (Reply 12):
The autopilots on normal pilot-controlled aircraft aren't designed to produce the rate of control surface change that would be required for equivalent performance and safe flight in all flight regimes,

That's not generally true on FBW airplanes. Autopilots are often limited in the amount of control they can command (e.g. 30 degrees bank) but, in a FBW control system, it's the flight controls (which are the same for the AP or the human) that figure out what the surfaces actually do. It's entirely possible for the AP to get *more* rate of control surface change than the human, just depending on what the AP asks for, especially if you have feed-forward control laws.

Tom.


User currently offlineMusang From United Kingdom, joined Apr 2001, 865 posts, RR: 7
Reply 14, posted (4 years 8 months 3 weeks 14 hours ago) and read 3618 times:

Quoting alwaysontherun (Reply 8):
but I believe there is a system that was designed to land automatically without any hydraulics, just using difference thrust levels for rolling the plane, steering the plane and obviously controlling flight level.

An MD-11 (the one in the purple MDC colours) was used in this project. If I remember correctly, successful landings were made using thrust and trim as opposed to flight control inputs, proving technical feasibility.

On an arguably related topic, one of the early concerns (although not within Airbus!) related to Airbus' FBW was how the aircraft could be controlled if all five Flight Control Computers (forgive the terminology, I've never flown one) failed. The way I heard the story, after no doubt experimenting in the sim, an A320 was landed a few times using only trim and thrust so as to prove to a critical pilot community (at the time) that it was possible. This was by test pilots intimately familiar with the type though. One wonders how ordinary line pilots would manage.

I look forward to those with more Airbus knowledge than me elaborating on the story.

Quoting mcdu (Reply 3):
it will nose down to chase the trimmed speed if power is reduced and it will nose up to chase the trimmed speed if power is reduced. This is called "phugoid".

The second "reduced" no doubt should be "increased". The pitch/thrust relationship is not called phugoid. What tdscanuck said, with the addition that a phugoid doesn't have to be self-damping. See below.

Most aircraft are dynamically stable in pitch, or have positive pitch stability, and the induced oscillations will decrease over time i.e. smooth out (maybe over several minutes) back to constant pitch/altitude flight.

A neutrally pitch stable aircraft keeps oscillating up and down without reducing the amplitude of the oscillations. Not inherently dangerous, but undesireable. The vertical flight path approximates a sine wave, or displays sinusoidal motion.

Having negative pitch stability or being dynamically unstable in pitch, means the oscillations will, if left alone, increase in amplitude. Clearly a bad thing.

The point is, all three of these are examples of phugoidal motion. [The Advanced Pilots Flight Manual, Bill Kershner, p 126] In a +vely stable case, a thrust change and its resultant pitch change would induce phugoid motion, which would eventually damp itself out. Clearly an advantageous characteristic in a transport aircraft. The word Phugoid refers to the geometric shape of the curve.

Quoting MrSkyGuy (Reply 7):
not to shoot my already swiss-cheese technical question full of more holes.

Don't beat yourself up! T'was a good, thought provoking question.

Regards - musang


User currently offlinealwaysontherun From Netherlands Antilles, joined Jan 2010, 464 posts, RR: 0
Reply 15, posted (4 years 8 months 3 weeks 12 hours ago) and read 3587 times:

Quoting tdscanuck (Reply 11):

It's safer and easier to put that engineering effort into making sure you never end up in that situation. Also, with the heavy preponderance of twins now, it's that much more difficult to implement good pitch control using thrust only.

Point taken, preventing it is always better.
I did not know that it was that much more difficult (expen$ive?) for a twin, compared to 3 or 4 holers.
Is there no chance of a manufacturer supplying this technology as a 2nd (or 3rd) backup within more advanced FBW technologies?

Does Air Force 1 have this at all?

With regards to preventing you from ever losing all flight controls, are hydraulic lines reinforced these days, or just better positioned where an impact to the aircraft can not take out all hydraulics at once?


### "I am always on the Run"###



"Failure is not an option, it comes standard in any Windows product" - an anonymous MAC owner.
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 16, posted (4 years 8 months 3 weeks 9 hours ago) and read 3517 times:

Quoting alwaysontherun (Reply 15):
I did not know that it was that much more difficult (expen$ive?) for a twin, compared to 3 or 4 holers.

The problem on a twin is that you've got no way to decouple thrust and pitch. On a trijet, because of the vertical separation of the engines, you can produce a pitch moment without changing total thrust. On a twin or quad, you have to simultaneously change thrust and pitch moment...it's not an insurmountable problem, but it makes it considerably more difficult.

Quoting alwaysontherun (Reply 15):
Is there no chance of a manufacturer supplying this technology as a 2nd (or 3rd) backup within more advanced FBW technologies?

I wouldn't say "zero", since it's technically possible, but I can't see how it would ever survive a cost-benefit analysis. The flight control system is already required to be essentially infallible in order to get certification in the first place, so the statistical benefit of such a system is basically zero...there's no way to justify the extra investment.

Quoting alwaysontherun (Reply 15):
Does Air Force 1 have this at all?

Air Force 1 is a 747-classic, which means it doesn't have FBW anyway. The only way to implement such controls is via the pilots...that said, I bet AF1 has really really really good pilots.

Quoting alwaysontherun (Reply 15):
With regards to preventing you from ever losing all flight controls, are hydraulic lines reinforced these days, or just better positioned where an impact to the aircraft can not take out all hydraulics at once?

Hydraulic lines are not reinforced to withstand external impacts. The goal is met by separation of systems, redundancy, locating systems out of likely impact areas, and hydraulic fusing.

Tom.


User currently offlinealwaysontherun From Netherlands Antilles, joined Jan 2010, 464 posts, RR: 0
Reply 17, posted (4 years 8 months 2 weeks 6 days 9 hours ago) and read 3309 times:

Quoting tdscanuck (Reply 16):
Air Force 1 is a 747-classic, which means it doesn't have FBW anyway.

Yeah, okay! I knew that, but I guessed that it is not your classic "classic", with some additional toys and tools to play with. I guess they upgrade technology as they go.

Quoting tdscanuck (Reply 16):
that said, I bet AF1 has really really really good pilots.

I assume it is a job that is really really really hard to get!
A million of hours without incidents on the 747 classic to start with, and a perfect security record. If you so much as spent "1 hour in detention" at primary school, you are out. Am I warm?



Quoting tdscanuck (Reply 16):

Hydraulic lines are not reinforced to withstand external impacts. The goal is met by separation of systems, redundancy, locating systems out of likely impact areas, and hydraulic fusing.

Okay, so I guess the hydraulic lines to the empennage run on both the right and the left side of the plane, yeah?
More one way valves to prevent it from draining too quickly, I guess.
Is there any record of a major hydraulic failure on a modern jet, where all systems were affected at once?
Is it as infallible as it is supposed to be?

Cheers,

### "I am always on the Run"###



"Failure is not an option, it comes standard in any Windows product" - an anonymous MAC owner.
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 18, posted (4 years 8 months 2 weeks 6 days 7 hours ago) and read 3251 times:

Quoting alwaysontherun (Reply 17):
Okay, so I guess the hydraulic lines to the empennage run on both the right and the left side of the plane, yeah?

They should, yes. Most large aircraft have three systems (some have four) and they should be well separated in the fuselage and empennage.

Quoting alwaysontherun (Reply 17):
More one way valves to prevent it from draining too quickly, I guess.

Yes. That's what hydraulic fuses are for. You have one-ways (check valves), volume- and rate-sensitive fuses, and standpipes to help ensure that failures in a non-critical area of the system don't jeopardize a critical function.

Quoting alwaysontherun (Reply 17):
Is there any record of a major hydraulic failure on a modern jet, where all systems were affected at once?

The DC-10 in Sioux City is the classic case, as was the Airbus that got hit by a SAM in Baghdad. But Im' not sure if you're classifying those as "modern jets."

Quoting alwaysontherun (Reply 17):
Is it as infallible as it is supposed to be?

Intrinsically, I think they hydraulic system is. You need to split out external factors...for example, if you suffer total power failure (no engines, no APU) it's not the hydraulics' fault that they can't provide power. The overall air transport system is not as infallible as it's supposed to be (if it met the target, we'd basically never have crashes) but it it way (way way way) more infallible than it needs to be.

tom.


User currently offlinealwaysontherun From Netherlands Antilles, joined Jan 2010, 464 posts, RR: 0
Reply 19, posted (4 years 8 months 2 weeks 6 days 6 hours ago) and read 3240 times:

Quoting tdscanuck (Reply 18):

The DC-10 in Sioux City is the classic case, as was the Airbus that got hit by a SAM in Baghdad. But Im' not sure if you're classifying those as "modern jets."

I actually meant the generation after that, I thought the 2 cases you mentioned were the classic "lessons learned" cases, on which the improved design was based.

Quoting tdscanuck (Reply 18):
but it is way (way way way) more infallible than it needs to be.

Impressive stuff!

Thanks Tom, I will leave you in peace.
(until something else pops up in my mind).

### "I am always on the Run"###



"Failure is not an option, it comes standard in any Windows product" - an anonymous MAC owner.
User currently offlineANITIX87 From United States of America, joined Mar 2005, 3308 posts, RR: 13
Reply 20, posted (4 years 8 months 2 weeks 6 days 5 hours ago) and read 3216 times:
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Quoting alwaysontherun (Reply 19):
Thanks Tom, I will leave you in peace.

Then I'll take over instead.

Quoting tdscanuck (Reply 16):
The problem on a twin is that you've got no way to decouple thrust and pitch. On a trijet, because of the vertical separation of the engines, you can produce a pitch moment without changing total thrust. On a twin or quad, you have to simultaneously change thrust and pitch moment...it's not an insurmountable problem, but it makes it considerably more difficult.

On a slightly unrelated note, how would a quad do? The engines are all on the wings but with sufficient dyhedral (or anhedral) could you obtain significant pitch control? I doubt it'd be as much as a tri-jet but would it be noticeably improved versus a twin? Similarly, for a t-tail twin, would the placement of the two engines at the back (and their pitch upwards for airflow reasons) allow good pitch control via thrust? Or would this be just as difficult as a twin with wing-mounted engines?

TIS



www.stellaryear.com: Canon EOS 50D, Canon EOS 5DMkII, Sigma 50mm 1.4, Canon 24-70 2.8L II, Canon 100mm 2.8L, Canon 100-4
User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 21, posted (4 years 8 months 2 weeks 6 days 4 hours ago) and read 3211 times:

Quoting alwaysontherun (Reply 19):
I actually meant the generation after that, I thought the 2 cases you mentioned were the classic "lessons learned" cases, on which the improved design was based.

That's what I suspected you meant...in that case, I can't think of any cases of total hydraulic failure in the modern generation. That's not to say it hasn't happened, but there's no obvious cases like there are for the prior generation.

Quoting ANITIX87 (Reply 20):
On a slightly unrelated note, how would a quad do? The engines are all on the wings but with sufficient dyhedral (or anhedral) could you obtain significant pitch control?

The amount of pitch control would depend entirely on the vertical separation between the inboard and ouboard engines...in theory, it would work, but the details would be aircraft specific.

Quoting ANITIX87 (Reply 20):
I doubt it'd be as much as a tri-jet but would it be noticeably improved versus a twin?

Given that it's zero on a twin, I have to suspect there'd be some noticeable improvement.

Quoting ANITIX87 (Reply 20):
Similarly, for a t-tail twin, would the placement of the two engines at the back (and their pitch upwards for airflow reasons) allow good pitch control via thrust? Or would this be just as difficult as a twin with wing-mounted engines?

I think it would probably be worse...nobody pays much attention to the vertical placement of the CG, but I suspect that the rear-mounted engines have less vertical separation from the CG than on a wing-mounted engine. The angle on the tail engines to match local airflow is so small that the vertical component of thrust would be pretty tiny...although it's on a long moment arm. I don't have enough numbers to hand to answer definitively.

Tom.


User currently offlineANITIX87 From United States of America, joined Mar 2005, 3308 posts, RR: 13
Reply 22, posted (4 years 8 months 2 weeks 6 days 4 hours ago) and read 3207 times:
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Quoting tdscanuck (Reply 21):
but I suspect that the rear-mounted engines have less vertical separation from the CG than on a wing-mounted engine.

That makes too much sense for me to have thought of it on my own.

Thanks.

TIS



www.stellaryear.com: Canon EOS 50D, Canon EOS 5DMkII, Sigma 50mm 1.4, Canon 24-70 2.8L II, Canon 100mm 2.8L, Canon 100-4
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