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Post by lnouvo on Feb 25, 2010 0:36:24 GMT
Hi all
From few days I'm flying HJG DC-8-62 and did not find any manual for correct pilot practice. I have a good practice of recent jets and find the settings by my own, or thru manuals, but with the DC-8, without A/T, I get some difficulties wih the descent at least.
Flying at FL360 @ 480 Kts, shutting gas off, should I want to keep a constant ROD, it seems not to be able to get more than 1000'/mn without getting the horrible overspeed horn shout. Should I want to use the constant IAS control, ROD speed gently yaws from minus 2000, to plus 2000, and after 150 NM I'm still not at FL 100 to reduce speed under 250 Kts.
Is this in accordance with real aircraft? Because it gets rather difficult to go along some actual STARs.
With a B 737 for instance, descent @ 2500'/ mn and 280Kts is easy, and from FL 360 is about 120 Nm only.
What's the trick to get a faster descent?
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Post by Dee Waldron - HJG on Feb 25, 2010 3:02:58 GMT
Pilotage. Control your airspeed with pitch, control your altitude with power. And no, that's not backwards.  Get the airplane in the correct attitude configuration before starting that descent. Practice it, and then report back.  Dee |
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Post by aerofoto - HJG Admin on Feb 25, 2010 10:05:16 GMT
Good advice Dee
I do have some FS figures regarding this .... but .... these aren't not close to me/accessible at the moment, so, I can't quote precisely.
HOWEVER ....
"IF" I'm flying at FL310, I always, as a matter of personal preference, start my descent at 150 miles (DME) from my intended airport destination.
I generally reduce power to "almost" idle immediately prior to commencing descent .... and I then start descending at around 2,000 FPM at first .... and gradually reduce this on the way down (it's here I need my precise altitude/ROC adjustment notes, but, can't access them at the moment) .... so that by the time I'm passing 10,000 FT I'm usually descending at no more than 1,000-750 FPM, with speed well under control, and are at around 30 miles (DME) from my destination airport.
With regard to B707/720, CV880. CV990, and DC8 aircraft in particular .... descents do require planning !
Without my FS flight notes that's the best I can advise at the moment .... apart from "practice makes perfect".
Mark C
AKL/NZ
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Post by lnouvo on Feb 25, 2010 15:55:51 GMT
Tks for your replies. I've just have to try various pitch configurations just before BOD, take notes of them, practice descent, observe what happens, and ...report.
Att aerofoto : should you find your notes back, please let me know.
Does anybody knows where to get copies (or extract) of DC-8 manuals?
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Post by Herman on Feb 25, 2010 16:24:25 GMT
Hi Inouvo;
Following the above advice should be helpfull.
For the DC-8 manuals check the DC-8 Performance thread under this section on page 2. It will give you the directions where to get this information.
Herman
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Post by aerofoto - HJG Admin on Feb 25, 2010 20:15:00 GMT
They're not lost or anything .... it's just that I'm trying to run a business, and organize .... and test .... things "HERE", as well as balancing all of this with home life .... and which somrtimes gets to be awkward !   ;D Here's my own FS performance observations in respect of descending the CV880/CV990 .... which should be similar to the DC8's except in respect of my quoted engine power references. PLEASE NOTE: I've constantly quoted EPR values (and which is wrong to do so .... I know) instead of N1's etc .... only because the EPR's are more easily read. You could try these profiles in respect of altitude/ROD changes and see how you get along. Again .... the DC8's, if managed properly, should fly/descent similarly, without overspeeding, and, to arrive at 10,000 by more-or-less 30 miles from any destination airport. Just for starters at least  .... try applying these CONVAIR descent profiles to the DC8's, and adjust them accordingly if necessary, and see how you get along And remember too .... these are FS performance observations using our models/FDE and not realworld procedures ;D Apart from my DC8 PANEL INSTALLATION & HANDLING NOTES (on the ABOUT HJG AIRCRAFT forum page) the best public documents available are the following .... DC8 PERFORMANXE & LIMITATIONS by Matt ZAGOREN .... available from FS.COM and ABSIM.COM .... search for the following file name .... dc8perf.zip (2mb)Covers .... DC8-20-50-61-62 AIR CANADA DC8 MANUAL by Jim HALINDA (2 files).... available from FS.COM .... search for the following file names .... dc8perfcharts.zip (3mb) Covers .... DC8-40-50-61-63 And .... dc8manual.zip (35mb) I use all of these myself ! Mark C AKL/NZ |
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Post by christrott on Feb 26, 2010 2:18:27 GMT
One more item to note - the maximum gear extension speed on the DC-8 is (if I remember) 255+ knots IAS, so if you do need to "get down" in a hurry, just put the gear down. Mind you, the passengers will think you're crazy, but flying the DC-8-73F in the modern ATC environment of VATSIM, I often find myself putting the gear down around 12,000 feet and leaving them down until landing because ATC starts me down late so I just carry a little power to keep the speed up at a reasonable speed and can easily maintain 2000 - 2500 FPM in the descent.
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Post by Dee Waldron - HJG on Feb 26, 2010 3:07:06 GMT
One final thought... Ages ago when I was learning how to fly, they taught us "the six Ps" (or was it 5?). Do they still teach that in ground school?
Dee
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Post by ky2i0 on Feb 26, 2010 3:55:19 GMT
Back in 1978 I was a passenger on a World Airways DC-8-?? I do know it was a strech and had a cargo door on the left side. The flight was a charter from McGuire AFB WRI to RAF Mildenhall, England. When we started our decent, the captain reversed the inboard engines. I am not joking. The inboard engines were reversed. I know as I was looking out the window and saw the clamshels close behind them ans the captain ever told us that the engines were reversed. Maybe this is what you have to do to get the plane to desend right.
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Post by aerofoto - HJG Admin on Feb 26, 2010 6:50:02 GMT
That'll be correct .... under some operating conditions ! The DC8 "was" capable and certified for inflight reverse .... on the 2 inboard engines only. Used, as I understand, to increase descent rate .... since the wing spoilers on DC8's can't be extended inflight in order to achieve this. I state "was" .... above .... because I remember John DETRICK telling me that ATI stopped using inflight reverse, particularly on their DC8 SUPER 70 aircraft .... due to excessive vibration which did, apparently, result in aircraft loosing engine cowlings. Whether or not other operators followed suite too I know not .... but .... probably not. Despite many past attempts and our investigations unfortuately inflight reverse thrust is not possible within our DC8 simulation ! "YES" .... that's another authorized procedure to slow DC8's down too .... but .... I guess .... one that's only used (realworld) as a last resort. Again .... I don't have access to my own DC8 FS notes at the moment, but, so long as descents are planned in advance and managed well .... all the way down .... then I don't recall running into speed problems. I suspect that what Chris is saying .... in relation to VATSIM ATC .... is probably borne of the fact that VATSIM ATC is probably more accustomed more to catering for modern rather than geriatric jetliners profiles like the DC8  Mark C AKL/NZ |
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Post by skyking on Feb 26, 2010 23:01:29 GMT
Uhhh.....that 255 kt thing for the gear was related to the DC-SEVEN.....NOT any DC-8. DC-8 Gear Speeds for Max Operating and Max Extended are 230KIAS/.65MACH. But, you're right on the reverse in-flight thing. Inboards ONLY. On the CFM DC-8s, it was not recommended because of the sudden jolt that could scare passengers. And there WAS a big jolt on the -71. Everyone tried it when they came out to "see for themselves" just what it was like. It was NOT unsafe. But with proper planning and not allowing ATC to fly your airplane, none of these things were needed to get the airplane down. Rarely did you need more than 2500FPM in descent. 4000 was considered max for passenger comfort. I thought 2500 was max for "MY" passenger comfort. |
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Post by lnouvo on Feb 28, 2010 23:22:35 GMT
Tks to all.
I pick several ideas :
1) program reduction of ROD by steps all along the descent, instead of waiting for overspeed horn
2) reverse inboard engines (if FS & HJG allows it!)
3) drop down gear under 255 Kts (I already used this procedure on other jets, when too close of the airport, my FS damage setting beeing turned off !).
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Post by skyking on Mar 1, 2010 0:50:49 GMT
If you start down early enough, you won't need to worry about much. And again.....gear speed on the DC-8s is 230 NOT 255. A good "rule of thumb" is three times your altitude plus ten miles. In other words if you're at FL300, start down at 90+10, or 100 miles out. I always tried to start down at 3X plus 20 miles, especially in the CFM powered DC-8-71. They had more residual thrust. I'd try and stay away from the gear and reverse thing if possible. You can always do a 360 and get down too.
Have fun.
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Post by aerofoto - HJG Admin on Mar 1, 2010 1:14:53 GMT
"INUOVO" .... once again .... "IF" you plan your descent properly/correctly .... in advance (perhaps along the lines of my CV880 and CV990 descent profiles as presented above) ..... then you should not run into any speed related problems during descent .... and therefore should not end up "ringing the bell", or requiring gear extension at high speeds, or even end up having to do a 360 orbit either. "REMEMBER" .... planning, and staying in front of the aircraft/simulation, is an essential element which must be mastered in order to be able fly these aircraft/simulations well .... particularly in respect of the descent process .... as unlike is the case with B707/720, CV880, CV990, and most other jetliners too, the wing spoilers on DC8's cannot/"MUST NOT" be deployed inflight and are therefore unavailable to assist the descent. "REMEMBER ALSO" .... inflight reverse thrust is not available within our simulation. It "IS" available in the realworld DC8 .... we know that .... but even so .... I've never flown, realworld (AIR NEW ZEALAND -52's, and HAWAIIAN AIRLINES -62's and their -63), on any DC8 when this option has actually been employed. Inflight reverse, on the inboard engines (only), is available, if needed, for sure, but, that by no means implies it always has to be used as a constant procedure .... unless really necessary ! Cruising at FL310 .... I generally always start down at around 150 miles (DME) from my destination airport, reducing power as I go down, as well as adjusting my ROD too .... only if I sense it necessary to do so .... and have never, yet, screwed/botched a descent/approach/landing. Keep on practicing mon amie .... and I'm sure you'll eventually master things quite adequately ! Mark C AKL/NZ |
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Post by lnouvo on Jun 6, 2010 17:24:24 GMT
Hi all
Recently discussing with a retired DC8 & 707 pilot about the critical descent procedure for the DC8, he let me know that he had an easier control by adjusting the pitch setting from the beginning of the descent, down to the final approach.
Unfortunately he is not a flightsimmer at all, and reluctant to come to our "game", and did not tell me more about his procedure.
Do you know it? I tried to do that with a DC8 - 33, but did not find a pitch gauge. Therefore, how do you set and adjust it?
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;D
.... try applying these CONVAIR descent profiles to the DC8's, and adjust them accordingly if necessary, and see how you get along 
