|
Post by emanuele on Mar 15, 2013 10:42:27 GMT
Yesterday I've flown for the first time the excellent HJG's DC-8-63F, experiencing some flying problems, especially concerning the engines power. In fact, I could climb at 280kts and 2400 ft/min of V/S with 20% of thrust, and to descent at 280 kts I have to be in idle and less than 1000 ft/min of V/S. At 1000 ft/min IAS incresed to 300 kts. I don't remember exactly, however aircrat was not heavy. So, this morning I've started to search infos in this forum, finding some gripes concerning power problems attributed to the FDE. Replies of developers was that the problems are caused by error in flying. Then I've found a thread where there is reported a document, writed by Aerofoto and named "DC8 BASIC FLYING GUIDES" but I don't found it, neither with the "Search" function of the forum. So, can you confirm me that my climb and descent problems are caused by wrong flight and can inform me where I can find that document?
Thank in advance for any help, with my best regards
|
|
|
Post by Dan K. Hansen on Mar 18, 2013 22:06:33 GMT
|
|
|
Post by aerofoto - HJG Admin on Mar 19, 2013 7:54:27 GMT
Are you using HJG supplied panels for this aircraft .... OR .... default MSFS supplied panel options .... OR .... other DC8 panel options provided by non-HJG authors ? For correct perfornmance indications .... HJG (only) panel options "must" be used. Due to critical gauge/FDE/panel relationships/interactions (calibrations) .... authentic/accurate performance cannot be guarunteed using any other non-HJG supplied files .... AND ADDITIONALLY .... it is also essential to ensure that the correct aircraft panel versions are used with each of the various aircraft base pack options as well. For any the current HJG DC8-62 and -62 aircraft base pack options .... one must use either of the following 2 HJG DC8 panel options only .... DC-8-62/63
DC-8-62/63 (INS)"FALSE" .... or otherwise "REDICULOUS/UNBELIEVABLE" panel instrument indications (performances generally) can often be the result of incorrectly paired panel/aircraft base pack file options .... AND .... the gauges in non-HJG supplied panel options likely will not indicate authentically either. Whilst I "FREELY ACKNOWLEDGE" that some aspects of the current HJG DC8-62, -63, -72, and -73 (only) FDE's do, indeed, comprise of issues requiring attention (a project I've been attending to .... slowly .... "AS TIME PERMITS ME TO DO SO" .... over the past 24 months. It must be understood that these are the only simulations within the HJG inventory which have not, yet, been subjected to the same degree of fine tuning as has been applied to other HJG simulations .... since all previously applied DC8 FDE editing has, primarily, been focused around panel compatibilities only) .... EVEN SO .... there's no way that any of the current HJG DC8-63 SERIES simulations will/should be able climb at 2,400 FPM and with just 20% power .... even if one was incredibly light/empty .... unless one is using HJG DC8-63 SERIES simulations with the wrong aircraft base pack FDE and/or DC8 panel options."IF" airspeed does ever becomes a problem during a climb (with any simulation) .... then it can/should be kept under control by increasing the ROC .... which, still, typically, shouldn't ever see one climbing (with a full load) in excess of more than around 3,000 FPM .... at the very most. HOWEVER .... a DC8-70 SERIES PFE once told me that with an "exceptionally light load" and in the "right operating conditions" too (probably not practice-able in FS) .... DC8-70's have, sometimes, been known to be capable of performing an "initial ROC" of around 6,000 FPM .... believe it or not !!!! This doesn't mean that these simulations should be flown in this particular manner though ;D To me .... this might indicate that you're probably commencing your descent both too close to your destination and/or at too high an airspeed to start with also. The same DC8-70 SERIES PFE also once told me that there used to be a saying among the real world DC8 community in that .... "DC8's can go down fast, but, not slow down fast". Descent .... in particular .... needs to be planned. One is well/best advised to slow down .... considerably .... before ever commencing ones descent .... with airspeed, ROD, and distance to run each being closely monitored all the way down .... and with the airspeed then being adjusted/controlled accordingly primarily through the ROD. Doing this successfully .... and despite (some) acknowledged FDE issues (being corrected by me .... slowly) can require a TOD of up to 150 DME from any destination airport (depending on the altitude of ones destination airport of course) .... and with engine thrust, and consequentially airspeed also, being reduced, considerably, before ever commencing the descent Apart from the "DC8 PANEL INSTALLATION & HANDLING NOTES" posting (as linked to above by Dan) I've not, yet, ever released my "DC8 BASIC FLYING GUIDE/S" .... although the above referenced information does, provide, some manner of "very basic guidence". NONE THE LESS .... I'm well established with writing a "BASIC FLYING GUIDE" for each of the DC8 family, but, posting any of this information is pointless until the new FDE's have been completed .... and then thoroughly studied .... as it's during these testing processes that I compile such notes/guides as I've done for most other HJG simulations. Part of the reason why this hasn't, yet, been done, by me, for any of the DC8's due to the fact that the DC8-10 through 40 family, the DC8 50 family, the DC8-60 family, and DC8-70 family also .... each fly "so differently from each other" that the preparation of such "BASIC FLYING GUIDES" for these aircraft requires quite a radically different approach to it in order for each type to be represented/guided properly. Most other families of HJG aircraft simulations do each fly similarly .... but differently all the same too .... BUT .... this's actually so more more true of the B707 and DC8 family in particular. This's also .... "vaguely" .... representative of the fact that realworld pilots flying B707's and DC8's often needed to be "TYPE RATED" in order to become licensed to fly each successive generation/advance of these particular family of aircraft. I "WILL .... EVENTUALLY" .... make these new notes/guides available, but, they'll still be a while, yet, in comming Mark C AKL/NZ
|
|
|
Post by emanuele on Mar 21, 2013 8:39:08 GMT
Dear Dan, thank your reply, I've already read that thread and, I hope, applied all the reported instructions. Dear Mark, many many thanks for your infos. I can tell you that I use HJG panel for the 63 model, downloadable from this page: simviation.com/hjg/panels/douglas.htmAbout the base pack I use this one: simviation.com/hjg/aircraft/douglas/dc-8-63f.htmHowever, I will check that all files are saved in the right folders and used in the right mode. About the climb, as I've already written, in my first flight I was not heavy, I think about the half, or 70% of the Max Gross Weight. So, it could be this factor to permit me to climb so fast and with so little power. The descent... of course I've started to go down a bit too late compared to the optimun TOD, for the simply fact that I use FS ATC.... with all the problems that this involves. In the next flight I will try the "rule ot three" (I'm not sure that this is the right english name... it's the rule to subtract the airport altitude to the aircraft altitude and multiply the result by three, this is the TOD). Concerning your guide, don't worry, I understand that the free time for this hobby is never enough. ;-)) Thanks again!
|
|
|
Post by aerofoto - HJG Admin on Mar 21, 2013 19:25:36 GMT
In your particular case ....
The only thing I can think of that might result in this sort of flight behavior (above) is if you were "POSSIBLY" (even inadvertently) using a DC8-70 SERIES AIR.FILE with your DC8-63 simulation.
There "aRE" (as I've acknowledged in the past) some minor issues with the current HJG DC8-62, -62, -72, and -73 AIR data.
In the case of the Dc8-62 and -63 these issues result in a tendency for these particular simulations to be a little bit more (too much) "slippery" than the rest of the HJG DC8 family .... with the DC8-73 (only as I recall) also suffering from an inverted N1/N2 engine gauge inactivation (the N1's start to exceed the 2's from a certain altitude) issue.
In the case of "slipperiness" .... the DC8-63, still, should not be able to climb at 2,400 FPM at just 20% power .... even with a roughly 70% payload .... HOWEVER .... and as I mentioned in my first reply posting, "IF" airspeed ever becomes an issue during climb (too fast) then the the ROC should be adjusted (increased) in order to try and keep it under control (this applies to any simulation .... HJG or otherwise) .... AND .... in the case of descent, the ROD decreased in order to keep it under control also, but which will, if commencing descent from cruising altitude (31,000 FT or greater), impose the need to begin descending from a greater distance (at least 150 DME from the destination airport) due to the necessary shallower descent angle then required.
Until I release the new DC8 FDE edits I've been working on (which do, now, result in vastly superior/more realistic flight behavior), the above are the best work-around in respect of the current minor impositions/discrepancies .... short of you, possibly/maybe, having an AIR.FILE mix up of the type I suggested earlier.
Mark C AKL/NZ
|
|
|
Post by emanuele on Mar 22, 2013 11:05:44 GMT
Dear Mark, first of all I confirm you that I'm using DC-8-63F_2k4.air file, extracted from the HJG_Douglas_DC-8-63F_v5.zip base pack. So, yesterday I've flown for the second time the the DC-8-63F and I was able to reduce the climb problems with a more weight. Now I can climb at 2400 ft/min, at 280-290 kts with 40-50 % of N2. But the descent is still too slippery. I had to descent from 32000 ft to 1000 ft and I've started at 100 NM from the destination (32000 - 1000 = 31*3 = 93 NM). But also in this case I had to descent with a ROD of 1000/ft to maintain 290-300 kts at idle. With this ROD I am arrived too high so I had to increase the ROD to 2000 ft/min and descent with first step of flap extracted. Hovewer, what I tell you absolutely is not a criticism to your FREE work, but also to understand what I'm wrong. Many many thanks!
|
|
|
Post by Dee Waldron - HJG on Mar 22, 2013 12:28:01 GMT
My I suggest some basic flying skill might be in order here. You need to get the airplane in the correct attitude. It was once said on this very forum by a real DC-8 captain: "You cannot go down and slow down at the same time!" Basic flying skill: Control altitude with power, and control airspeed with pitch. So before you start your descent, reduce power and then pitch the nose up slightly with long trim, just a touch up should do it. Now you can control the ROD by adding or reducing power. A little practice, and report back. Dee
|
|
|
Post by emanuele on Mar 22, 2013 12:39:24 GMT
Dee, what do you refer with "long trim"? If I pitch up the trim, airplane climbs. When I have to start the descent I set thottles in idle, and when start to set a negative vertical speed on AP, it move the trim down, pitch down. I can try also to descent manually, disconnecting the AP, but if i pitch up the trim and reduce speed, I think that aircraft will stall. Have I misunderstood?
|
|
|
Post by walterleo on Mar 22, 2013 13:44:22 GMT
Hi Manuelle:
There is a basic common misunderstanding that an airplane goes through the air like a knife trough butter. An airplane flies by the lift created by its wings controlled by the control surfaces. It maintains altitude by the power of its engines pushing it forward but it can do that at various speeds in a jet between ca. 1000km/h and ca. 300 km/h. This is done by changing the angle of attack (AoA). With flaps which create more lift it will fly at the same altitude between 400 and ca 230 km/h. A stall occures only if you exceed the permissible angle of attack. If you reduce power and maintain your attitude it will fly the same speed but descending. Means you can stall the airplane also descending, if the forward push of its engines is not enough to maintain the speed and you force the airplane to maintain its present attitude against its inherent tendency to lower the nose and gain speed again. When Dee is referring to "long trim": Big airplanes have more than one trim system. Normally the angle of attack of its horizontal stabilizers are changed according the actual weight and center of gravity, the trim of the elevator does in a big airplane the fine tuning. If you find somewhere Wolfgang Langwisches book "Stick and Rudder" buy it, whole generations of pilots got their flying wisdom from that.
Kind regards
Walter
|
|
|
Post by emanuele on Mar 22, 2013 14:08:03 GMT
Ok Walter and thank you for your infos. I know those, but this means that in the DC-8 it is possible to descent manually only, controlling the vertical speed by the power and the speed by the trim that controls fine tuning of angle of attack, but is not possible to descent using the AP Vertical Speed control (that manage the trim)?
|
|
|
Post by Herman on Mar 22, 2013 14:58:34 GMT
In addition to what has already been said, probably your best solution is to do what Mark has already mentioned...start your descend early. No need to stick precisely with the 3 to 1 rule.
If you are using ATC, just request a descend, and don't wait until they request it.
From what I recall I did'nt have a problem with the DC-8's meeting the descend profile ( about 2000ft\min.) and ATC instructions but I do recall having to adjust my rate of descends in order to meet the 250kt. speed restriction below 10,000ft.
And you can always do a 360 deg. turn if you find that you are unable to make the approach and landing safely.
I believe on the RW DC-8's it was possible to use a bit of reverse thrust on the inboard engines to provide some sort of speed braking, but I think it was used sparingly because it resulted in considerable airframe vibration which was a bit uncomfortable for the passengers.
Herman
|
|
|
Post by emanuele on Mar 22, 2013 16:33:24 GMT
|
|
|
Post by bluestar on Mar 22, 2013 18:05:23 GMT
Basic flying skill: Control altitude with power, and control airspeed with pitch. Dee 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. Billy
|
|
|
Post by walterleo on Mar 22, 2013 18:32:05 GMT
Hi Emanuele:
Descent by autopilot:
The DC8 AP has as I remember the facility of holding airspeed or mach without using the attitude wheel: You fly with Mach 0,8 at 30.000 feet and you are 120 NM away from your airport of destination. Let the plane fly at altitude hold and pull back the power to idle, the plane decelerates to Mach 0,7 you push the mach hold button of the AP (NOT THE AUTO-THROTTLE). Slowly the airplane will lower its nose until descent around -2200/2500 ft/min. Wait for an airspeed of around 270 kts, change to speed hold and you will reach 10.000 ft ca 40 NM from your airport, with the attitude wheel reduce the descent until speed is below 250 kts, Speed hold another time and maybe a little power. In that way you should be down at 2000 ft and 250 kts ca 20 NM away from airport. Reduce attitude to 200 kts flaps 10 gear down power up to hold 180 kts second notch of flaps maneuver for glide-slope intercept, when glide-slope alive flaps 3 notch, when glide-slope going to middle full flaps and trim to hold the glides. It should come out in this way, that only small power changes are necessary to maintain around 145 kts and -700 ft/min. Happy landing
Walter
Please don't nail me on the exact numbers, but more or less it should work this way, check with Aerofotos flying guide.
Walter
|
|
|
Post by emanuele on Mar 22, 2013 18:57:07 GMT
Dear Walter, I have only to thank you for these infos. I will try!
ps: I've checked my DC-8, all seems to be ok.
|
|