Couple of Notes

[christrott]

I just started flying the DC-8's again with some frequency for the VA and I noticed a few things that I didn't think to look into previously that could explain some of the "odd" behaviors some are getting with respect to Rate of Climb, overpowered flight, and such.

1) On all my installed aircraft (DC-8-50s, 60's, and 70's), none of them have the flight surfaces (wings, tail, hstab) properly setup. They have no sweep, root chord of the wing is wrong, and the position of the surfaces vertically are wrong. This would explain not only the climb performance (straight wing has much better climb than swept) it would also explain why I was getting 5+ degrees of body angle even when properly loaded at the right altitude for the weight. This is *NOT* a knock against you guys, I may have done something to screw up my flight dynamics at some point, but I suspect that this may have been something introduced in the past that no one caught.

2) I downloaded the newest gauge pack recently and I've had several issues with the DC-8-50 (no INS) panel now like the fuel flow gauges aren't recording fuel usage, the transponder isn't working, and the click areas for the radios are really off. I think this may have something to do with the panels themselves, but I'm wondering if you guys changed something in the last 6-8 months since I re-installed all my DC-8 stuff for me to look at specifically.

3) I know that this may be VERY low on the list, but as I mentioned over in the Lockheed forum, the EPR gauges on the DC-8's don't seem to be properly calibrated. When I set to the expected fuel flow, the plane flies the expected cruise speed, but the EPR is down around 1.4 instead of 1.6+.

4) There is either a problem with the TAS gauge or the OAT/TAT gauge because the TAS showing doesn't match the temperature showing. For example, I was cruising from Munich to Shannon the other night (real time) and the OAT was showing around -20*C (+15* ISA) but my TAS was still showing 470 when it should have been showing somewhere around 490 if the temperature was right.

I'm not asking for fixes to the issues per say, but if someone could help me with where I should look to fix #2, #3 and #4, I can dig in with FS Panel Studio and fix it myself if it's possible. If #3 and #4 aren't easy fixes, then that's fine and I'll just mark it up as "known issue" and wait for when you guys decide to take the time whenever that may be.

[Herman]

Christrott;

With regards to your #1 statement.

I just uploaded the HJG DC-8-50 in Aeronaves livery and all looks normal ie. wing sweep, tail sweep, HS stabalizer sweep.

Are you sure you installed a DC-8?

Perhaps a Christmas office party has affected your vision a bit. ;D

Herman

[christrott]

Sorry, I guess I wasn't clear, I'm talking about the Flight Dynamics entries defining the flight surfaces. The visual model itself is excellent (in fact it's perfectly scale as my cargo modifications prove since I didn't have to do any "adjusting" to get it all to fit as I have with other aircraft).

[Herman]

So sorry. I just assumed that you were referring to the visual appearance of the aircraft.

I have'nt flown the 8's for a while, so I'll take one up to see if I get similar performance results.

Herman

[aerofoto - HJG Admin]

WELL .... I have mentioned .... several times over past months in fact .... that we do have new DC8 FDE which I've been trying to get uploaded for quite a while now .... but which has also had to constantly deferred in favor of the other new aircraft projects (B727, CARAVELLE, DC9, and L1011) which we've been fortunate enough to uploaded over the past almost 2 years.

Such delays can't be helped .... of course !

Just how much this DC8 FDE update is actually going to influence the curent flight peformance of all the DC8's I've yet to determine myself .... but .... "ALL" DC8 models will be implicated by this update .... when I can get the darned thing uploaded.

One thing I can say .... definitively .... is that the engine spooling rates of all of the DC8 models will be slowed .... to about what it should be (it's currently way too fast) .... and to roughly what is currently reflected per the current engine spoolup performances of the B707/B720's. These engine spoolup perfotrmances will vary between turbojet, fanjet, and modern turbofan engine types .... just as it currently does among the B707/B720's.

This DC8 FDE update will also be a good opportunity to correct that aircraft base pack issue/anomaly which Herman mentioned in is HU of yesterday.

That's about all I can tell everyone, at the moment, about the DC8 FDE update.

I wouldn't focus too much upon what may be observed per the current/original DC8 FDE .... other than the fact it represents all that we've got at the moment .... because all that will change "EVENTUALLY". ;D

A seperate FDE update will also become availavle for each of the C135 aircraft types too, but, has similarly been delayed by the same "other priorities".

Mark C
AKL/NZ

[Mike Monce - HJG]

I was actually thinking that in the next few weeks to get a head start on the DC8 FDE as Mark mentioned that it was on our "to do " list.

IF the aircraft geometry is that far out of line, then it may take awhile to get the whole thing back in shape. Wing sweep is important as it also affects the CG placement, believe it or not.

Mike

[Herman]

Here are some flight test results that I got with the HJG DC-8-50 latest V5 version.

In the aircraft cfg file the wing sweep shows 30.00 which is correct. No sweep is shown for the tail surfaces.

The aircraft GTOW was 314,000lbls, 315 is Max.

I used Standard temperature and pressure values at sealevel.

The Air Canada flight manual for the DC-8-50 called for the following TO perameters with 25deg. flaps.
EPR= 1.87
V1= 137knts
V2= 151knts
V2= 162knts

For the climb to 10,000ft. I used EPR of 1.60 to maintain 250knts with a climb rate of 2000ft\min.

Above 10000ft and to 24000ft I used EPRof 1.7 to maintain 300knts and 1500ft\min. climb.

Above 24000ft to FL280 I used EPR of 1.7 to maintain M.68 at 1000ft\min climb.

I leveled off at FL 280 because I figured that that was probably the proper cruising altitude for the weight of the aircraft.

At FL280 and M.80 my EPR was1.6

I am guessing that the DC-8-50 FDE is probably very close to the real thing,but then I could not confirm this with any former pilots who operated these aircraft.

I had no problem with tuning the radios. My mouse arrow was right over top of the numbers to change them.

My RAT temp gauge reading was -10deg celcius which is probably correct for standard atmospheric conditions.

Herman

[christrott]

Thanks for the responses guys.

Mike - I believe the CoG is actually set right looking at my aircraft in ACM, but remember I'm using my cargo modifications from the forum on these aircraft as well and I don't remember if I changed the default CG location in that. Changing the wing location will only resolve the "nose high" situation that some have reported because it'll shift the CoL to the correct position.

Herman - at FL280, the TAT should be much lower, somewhere around -40. If you want to check, the Matt Zagoren charts for the DC-8 have the expected TAS and TAT for a given altitude listed.

[Herman]

Yes of course,the OAT should be closer to -40celsius.
( lapse rate normaly being 2 degs.\1000ft. )
The gauge expresses RAT; whatever that means, perhaps Real Air Temperature?

AS far as the cruise attitude in the DC-8-50 is concerned.....I found it to be normal....2.5 deg. nose up....at M.80

I'll take a spin in a series 63 to see how it performs.

Herman

[Herman]

As Mark has mentioned the DC-8's, in particular the 60 series, are in need of extensive changes in a few areas to reflect more accurate perameters.

The biggest differences I saw between the DC-8-50 and DC-8-63 was in the EPR settings and fuel flows. The DC-8-50 was I believe closer to what it should be.

For example fot the DC-8-50 at a cruise altitude of FL310 and M.80 the EPR was about 1.68 and fuel consumption about 3,700lbs.\hr\engine.

For the DC-8-63 at the same altitude EPR was 1.06 and a fuel consumption of 1,350lbs.\hr\engine. Quite a big difference.

As far as climb and cruise attitudes both aircraft were about the same, about 5deg. and 2.5deg nose up respectively at their normal climb and cruising speeds of M.68 and M.80.

The fuel flow meters were working OK on both aircraft in as much that they were moving during thrust changes.

Herman

[jimhalinda]

According to flightsim.com, RAT=Ram Air Temperature is the OAT plus the temperature rise due the complete slowing down of the air stream in the temperature sensor.

So I'd expect it to be higher than OAT, although I have no idea by how much.

Regards,

Jim

[jimhalinda]

Oh, and as a big fan of the DC-8, please HJG, I know you've been busy but I'd love to see improved FDEs for your DC-8s! I find the 707s more challenging (and rewarding) to fly, and if the DC-8s can be made more realistic, please make the updates available!

Regards,

Jim

[christrott]

Okay, I just re-downloaded the DC-8-50F file, and verified that what I have is the same as what's available for download -

[airplane_geometry]
wing_area=2758.000000
wing_span=139.666667
wing_root_chord=19.750000
wing_dihedral=6.498413
wing_incidence=1.0
wing_twist=0
oswald_efficiency_factor=1.00000
wing_winglets_flag=0
wing_sweep=0.000000
wing_pos_apex_lon=4.000000
wing_pos_apex_vert=0.000000
htail_area=559.000000
htail_span=47.500000
htail_pos_lon=-93.583333
htail_pos_vert=0.000000
htail_incidence=0.000000
htail_sweep=0.000000
vtail_area=352.000000
vtail_span=21.391587
vtail_sweep=0.000000
vtail_pos_lon=-88.500000
vtail_pos_vert=5.833333
elevator_area=139.750000
aileron_area=117.160000
rudder_area=59.840000
elevator_up_limit=27.501974
elevator_down_limit=20.626481
aileron_up_limit=19.480565
aileron_down_limit=14.896903
rudder_limit=23.491270
elevator_trim_limit=19.480565
spoiler_limit=59.988681
spoilerons_available=0
aileron_to_spoileron_gain=0.000000
min_ailerons_for_spoilerons=0.000000
min_flaps_for_spoilerons=0.000000

(Important parts highlighted)

[christrott]

Also, for the panel stuff - it seems I had an old version of the panels somehow (everything was dated March 2007 instead of November 2007) so I've fixed that now. Hopefully that'll fix the engine indications.

RAT & TAT are the same thing. In fact, if you look, the gauge is actually named "dc8sw!_tat" and the base bitmap says TAT. Either way, the RAT/TAT gauge is supposed to read what the real air temperature is outside as an OAT gauge when moving a speeds greater than Mach 0.20 is unreliable and subject to surface heating error caused by the airflow.

[aerofoto - HJG Admin]

Hopefully that'll fix the engine indications.

"NO" .... it won't/shouldn't.

This won't be addressed until the new FDE is available .... that versioj I've been talking about, but, had to defer so constantly in favor of other projects.

When I get time !

Other than basic engine parameter indications .... this new FDE will also result in changes to engine spooling rates too (currently all DC8 engines spool way to quickly) so far as I'm aware .... and as I hinted above !

Mark C
AKL/NZ