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Post by aerofoto - HJG Admin on Mar 22, 2013 19:28:29 GMT
WELL .... as I've already mentioned a couple of times now .... I acknowledge that there "IS" an issue with the DC8-63 FDE .... which "DOES" result in difficulties such as that which you're experiencing/reporting. The only way to currently address these particular difficulties (before my FDE revisions are released) is to use the workaround which I promoted yesterday .... 1. Increasing the ROC if airspeed starts getting out of control during the climb .... along with flying with a much higher or full payload. 2. Start descending early .... 150 DME before your destination airport (less than that will simply not going to get down in time) .... and before ever commencing the descent engine power must be reduced, to result in a roughly 290 KIAS airspeed whilst still in level cruise (this need to be done before 150 DME tOD descent point), and then start going down .... and be prepared to monitor, and adjust, the ROD throughout your descent in order to keep the airspeed under control. This will still require a shallower than normal descent right throughout most of the descent. As a result of the current FDE discrepancy for this particular aircraft (remember I did also mention (above) that the DC8 FDE's have "not" been fine tuned to the same extent as those for other HJG simulations .... in fact these have been remained virtually untouched since around 2004 .... save for minor "panel compatibility" (only) related editing) .... there's "NO WAY" you'll ever get down in time if you don't start down from around 150 DME. Because of the same FDE discrepancy .... 120 DME is still too close/cutting things "pretty fine" .... AND .... using the customary 3 to 1 rule simply "will not" get you down to where you need to be within 10 DME of your destination airport. "EMAMANUELE" .... I have sent you a PM which may help  Mark C AKL/NZ
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Post by walterleo on Mar 23, 2013 10:02:33 GMT
 Hi Mark: One as I often forgets, that DC-8´s as early russian airliners had no airbrake usable in flight. But if speed/distance to airport starts to be a problem, one can use the gear to slow down in a descent. But its a "russian" method not an elegant one. Maybe Emanueles PAXs will wright angry letters to her airline in this case. But the real DC-8 could use the outer reversers inflight. And this was quite a racket for Paxs sitting near the wings.  Walter
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Post by aerofoto - HJG Admin on Mar 23, 2013 10:27:55 GMT
"YES" .... that's all very true in respect of ....
(1) inflight deployment of the wing spoilers being forbidden on all DC8's (in fact the DC8 is the only member among the family of first generation 4-engine jetliners to which this rule applies .... history having recorded at least 2 "very nasty" accidents resulting from inadvertent inflight deployment of the wing spoilers) .... and are, therefore, only available for ground deployment upon touchdown after landing.
(2) high-speed extension of the landing gear, as an "emergency" means means of slowing these aircraft down, is actually written into the real-world flight manual for all DC8's.
(3) On all DC8's (with the exception of SHIP ONE 1959 which was not, originally, fitted with engine thrust reversers) the use of inflight reverse thrust (on the inboard # 2 and # 3 engines only) is available on as a means of increasing the descent rate without accelerating too much .... HOWEVER .... a DC8 PFE has told me that this practice, on all DC8's (particularly the SUPER 70's) is now "banned" .... since both the vibration and pylon/wing oscillation imposed by the use of inflight reverse thrust had resultred in some of these aircraft actually shedding engine nacelle cowlings.
Still .... the greater part "EMANUELE's" problems "DO" stem from the AIR data discrepancy I've mentioned above .... and the only real work-around is that which I've been advocating above .... which results/imposes a much longer and shallower descent.
Mark C
AKL/NZ
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Post by Dee Waldron - HJG on Mar 23, 2013 10:33:16 GMT
Sadly, the thrust reverse trick will not work in FS. The FS program does not allow for reverse thrust in flight. Using the landing gear as an air brake is in fact, part of the -8s FM (Flight Manual). Personally, I've never used the AP for descents. But I am a hands-on kind of guy. That's just me! In this way, I never have any problem flying the -8 and making it do what I want it to do, instead of chasing after it! Dee |
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Post by Deleted on Mar 23, 2013 17:05:22 GMT
I am baffled If reverse thrusters are banned in all DC-8s, how do they slow down on runway without burning rubber tires???
I just installed HJG DC-8 cargo planes and would love to know the answer to question above before I fly those for first time.
Aharon
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Post by eastern1004 on Mar 23, 2013 17:31:16 GMT
"Next time you're lined up for take-off, pump that yoke back and forth and let me know when you get to flying speed."This guy was a ledgend in commercial aviation.
Legendary ignorance anyway!
Do the same thing with the yoke whilst FLYING and the point PROVES ITSELF!
AND if you turn off the autopilot and try to attain straight and level
you will find that 0 ft / min is attained by using the THROTTLE! Which also proves the point!
After attaining 0 ft/min advance the throttle, then come back here and tell us what the airplane did!
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Post by Herman on Mar 23, 2013 18:39:45 GMT
Aharon...they are talking about deployment of reverse thrust while airborne..not after landing.
Herman
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Post by acourt on Mar 23, 2013 18:51:47 GMT
I am baffled If reverse thrusters are banned in all DC-8s, how do they slow down on runway without burning rubber tires??? He's referring to the inflight use of reverse thrust. You can still use it all you want on the ground To clarify terms, jets are generally equipped with three systems: speedbrakes, flight spoilers, and ground spoilers. They are, however, generally the same pieces of metal moving out on the wing. Speedbrakes are used for speed control, increasing rate of descent, and such, inflight. Flight spoilers are used for roll control. Ground spoilers are used for aiding braking during landing. I know it's semantics, but technically one doesn't use the "spoilers" to help slow down in flight. You use speedbrakes. You also don't use "speedbrakes" on landing. That's ground spoilers. Confusing enough? ;D Here's an example... In a DC-9, I need to expedite my descent. I move the speedbrake handle aft, raising the spoiler panels on top of the wing. They only extend some of their available travel so as to not kill all the lift on the wing. Later on, I've slowed down to maneuver in the traffic pattern. I'm using the ailerons for roll control. But if I move the yoke far enough (more than about five degrees of yoke movement), I get some help from the flight spoilers. If I'm rolling right, the right spoiler panel will raise slightly, reducing the lift on that wing, and increasing my rate of roll. Once the gear are down, I pull the speedbrake handle up, arming the ground spoilers. On touchdown, all four spoiler panels raise to their maximum travel, killing much of the lift on the wings, putting most of the aircraft's weight on the ground for better braking. Whew... Anyway, the DC-8s spoilers don't have a speedbrake function in flight. So you're at the whim of nature, physics, and your excellent descent planning. As far as the argument (first heard by Orville and Wilbur) of whether power or pitch controls altitude and airspeed, most pilots know the real answer: altitude and airspeed are controlled by coordinated use of both power and pitch. Trying to use one without the other will only lead to trouble. |
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Post by walterleo on Mar 23, 2013 19:25:55 GMT
Hi:
Still one more braking method:
The so called 360 comes handy if Cap. or ATC or weather work against an elegant descent. With the consent of ATC one can make one or more full turns, loosing altitude and done correctly loosing speed also. As PAX I have experienced 2 times that in an airliner. In a MD 80 of China Eastern to loose altitude after overflying a thunderstorm and the airport below clearly visible for 3 or 4 360s. And in an Austrian Fokker 70 over the outer-marker for LOWW reason not clearly visible, but they came in quite high. As virtual pilots we can use that trick also if our planning was at fault, no reason for loosing faith in aviation.
Walter
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Post by Deleted on Mar 23, 2013 22:45:33 GMT
opppppssssss my apologies Good to know that I can use reverse thrusters after touchdown.
Aharon
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Post by Dee Waldron - HJG on Mar 24, 2013 7:40:43 GMT
>>I've heard this argument about airspeed being controlled with pitch as opposed to power. To quote one of the first captain's I flew with on the B707 - "Next time you're lined up for take-off, pump that yoke back and forth and let me know when you get to flying speed." This guy was a ledgend in commercial aviation.<< Maybe legendary in his own mind, but obviously didn't know anything about stick and rudder aerodynamics... The story he told you is actually an old joke about the difference in training between military jet-jocks and civil pilots. Heard it before... As mentioned previously in this thread, the fact of the matter becomes instantly apparent once the airplane is moving into the relative wind. My advise still stands: Turn off the AP and fly the darn airplane! Dee |
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Post by acourt on Mar 24, 2013 12:04:27 GMT
Emanuele,
Here's another way to plan your descent. You'll need to at least know what type of rate of descent you can maintain without overspeeding the airplane.
1) Determine the planned rate of descent. We'll use 1,000 feet per minute as an example.
2) Determine your ground speed. You can calculate it or use the GPS. We'll use 497 knots as an example.
3) Determine your ground speed in miles per minute. It's knots divided by 60. You don't need to be exact, so you can round the numbers. 497 becomes 500. Now drop the last digits, and you have 50 / 6. The answer is between 8 and 9 miles per minute. It's generally better to be leveling off early rather than late, so I'll use the higher number.
4) Now you have the magic number. Need to lose 10,000 feet? 10 times 9 equals 90 miles. Set the new altitude, and dial the VS down to 1000 fpm. Make sure not to overspeed.
Caveats:
1,000 fpm is a little slow. A descent at that rate from FL330 takes almost 300 miles. That's a little rough on fuel.
As you descend, your true airspeed and ground speed will change. By the time you get down to 10,000 feet, you'll be down to 4 or 5 miles per minute. Recalculate accordingly.
The math is easy for other rates of descent. Two thousand feet per minute takes half the time of 1,000 fpm, while 1,500 fpm is halfway between those. So if 1,000 fpm is 8 miles per minute, 2,000 fpm is 4 miles per minute, and 1,500 fpm is 6 minutes. Five hundred fpm is 16 miles per minute.
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Post by acourt on Mar 24, 2013 12:10:33 GMT
what do you refer with "long trim"? It's short for longitudinal trim, also known as pitch or elevator trim. The longitudinal axis of the airplane runs from the nose to the tail, and is controlled by the elevator. (Or the throttles, if you're a military pilot ;D. Flame suit ON!) Edited to fix the quote. |
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Post by emanuele on Mar 26, 2013 14:36:01 GMT
Many many thanks for all you replies, especially for your rule Acourt! And Mark, WELL .... as I've already mentioned a couple of times now .... I acknowledge that there "IS" an issue with the DC8-63 FDE .... which "DOES" result in difficulties such as that which you're experiencing/reporting. I was referring to the DC-8s' files installed in my PC, thinking I have done something wrong and not absolutely to your work. |
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Post by bluestar on Mar 26, 2013 15:55:20 GMT
>>I've heard this argument about airspeed being controlled with pitch as opposed to power. To quote one of the first captain's I flew with on the B707 - "Next time you're lined up for take-off, pump that yoke back and forth and let me know when you get to flying speed." This guy was a ledgend in commercial aviation.<< Maybe legendary in his own mind, but obviously didn't know anything about stick and rudder aerodynamics... The story he told you is actually an old joke about the difference in training between military jet-jocks and civil pilots. Heard it before... As mentioned previously in this thread, the fact of the matter becomes instantly apparent once the airplane is moving into the relative wind. My advise still stands: Turn off the AP and fly the darn airplane! Dee Mr. Waldron, My comment was meant to add a little humor to the conversation. The captain I was talking about had 30,000 hours and almost 20,000 hours in B747s when he retired. I feel he had a very good understanding of stick and rudder. He was one of the best sticks I ever flew with and more importantly he was a good teacher and person. Grace and Peace, Billy |
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