HJG Boeing 707-120 take-off related anomolies

[parkway]

At the risk of becoming a nuisance, I need to mention a couple of problems which appear to affect only me, but maybe someone else too.
1. MI doesn't kick in. In about a dozen attempts the MI has lit up only twice. What is the proper procedure for enabling this system? Should the engines be at idle or run up when switching on? How long do I wait before I put the passengers on a bus (7 minutes didn't do it, nor did powering down and back up again)?
2. Aircraft doesn't track on the runway properly. On take-off run it veers right as with a flat tire and requires constant adjustments to keep it on the runway.
As you may deduce I am new to jets, but not to FS (Simmer since 1980's) I have no T/O problems with other HJG aircraft. I have B707-120B (concerns recently resolved), DC8-50, DC8-62 and Convair 880M

[aerofoto - HJG Admin]

Call it "WATER INJECTION"system, or "WATER METHANOL INJECTION" system .... not MI .... or you're going to be at risk of folk not maybe understanding what you're trying to communicate.

If you're indeed using the B707-120 1959 panel with the early B707-120 aircraft .... OR .... the B707-138 1959 panel with the early B707-138 aircraft .... THEN you should have no problems whatsoever .... other than either "PILOT ERROR" or hardware calibration issues being likely the causative of any issues

These aircraft and panels have been "VERY WELL TESTED" prior to release .... and have not been further upgraded within the past approximately 24 months .... simpl because there's been no need to. No other similar issues have been reported "that I can immediately recall" either.

1. MI doesn't kick in. In about a dozen attempts the MI has lit up only twice. What is the proper procedure for enabling this system? Should the engines be at idle or run up when switching on? How long do I wait before I put the passengers on a bus (7 minutes didn't do it, nor did powering down and back up again)?

It must be remembered/borne in mind that early P&W JT3C type turbojets which powered B707-120 and B707-138 are very slow to spool up .... slower than later P&W JT3D fanjet engines which powered their corresponding B707-120B and B707-138B aircraft counterparts. This is a characteristic of these early jet engines and something we studied from realworld records in order to implement the most realistic performance both FS and our own current abilities to permit with these aircraft/panels/FDE.

Your engines should be running at idle speed prior to T/O power being applied .... with the aircrafts brakes locked "ON".

The 4 Water Injection switches can be selected "ON" prior to setting T/O power .... OR .... they can be activated partway during the engine spool up to reach T/O power .... in FS it really doesn't make much difference. I do, however, recommend the following procedures ....

Power advance should be to the maximum range of your throttle controller device .... power levers "all the way up". That can be done with a turbojet engine whereas with fanjet/turbofan engines power needs being set more cautiously/precisely).

It will take approximately 20 seconds for the engines to spool up to N1 97% (that "IS" normal for these enines) .... and it will take up to approximately 40 seconds for all 4 Water Injection lamps to illuminate/light-up .... and when they do these will not all illuminate/light-up at once, but rather, will vary slightly .... with all 4 lamps being illuminate by the passing of up to 40 seconds or so duration. Again .... this is from an engine idle, brakes "ON", power up to T/O.

Once all 4 Water Injection lamps have illuminated .... THEN release your brakes and commence you T/O roll.

"IF" your waiting "several minutes" for these Water Injection lamps to illuminate .... then that's "ODD" .... and I've never, ever, heard of such a delay. "IF" they're not illuminating at all .... then all I can suggest is that you might have a controller device calibration issue to contend with .... in that it may not be giving you "FULL POWER" when you believe it to have been set. I can't advise further than this I'm sorry.

Prior to even commencing T/O .... and at MGTOW .... you should have 30 degrees of flap set .... and a few units of elevator trim set also. Even on a long RWY (like the default MSFS KSEA RWY 13R/16L) your T/O roll will be slow .... and long .... requiring in excess of 3/4 of the RWY length to get airborne. The higher weight KC135-A is even more demanding/challenging.

ALSO .... the Water Injection lamps will extinguish, automatically, after about 3 minutes .... aftyer T/O .... simulating the thrust augmentation solution becomming exhausted. You will then note engine thrust indicastions, per the gauges, reducing slightly .... this is quite normal without the boost. These switches can then be selected "OFF", manually, and the power can either be left up (again that can be done with a turbojet engine, but, watch the EGT's) or reduced slightly depending on what sort of climb profile you intend to follow up to cruising altitude. On the way up to cruising altitude you may be forced to "STEP CLIMB" .... especially if you are heavy. My own testing of all vintages of these panels and aircraft over the past 5 years confirms that the following is the best procedure by which to fly both the early B707-120 and B707-138 with their respective 1959 type panels ....

B707-120 (using B707-120 1959 panel

MGTOW 257,000 LBS.

4X P&W JT3C-6 turbojet engines rated at 11,200 LBS thrust e/a .... 13,500 LBS thrust e/a with water/methanol injection.

Activate 4 Water/Methanol Injection switches. Set maximum T/O thrust. Do not release brakes to commence T/O roll until all 4 WI anunciator lamps have illuminated .... at approximately EPR 2.55.

PLEASE NOTE: Water/Methanol injection/boost is available for approximately 3 minutes only during T/O and C/O.

Initial ROC 1,000-1,500 FPM.

After gear and flap retraction maintain full power. Increase ROC to 2,500 FPM until passing 8,000 FT. Assume the following schedule for best climb performance ....

- 8,000 FT reduce ROC to 2,000 FPM until 18,000 FT
- 18,000 FT reduce ROC to 1,800 FPM until 20,000 FT
- 20,000 FT reduce ROC to 1,500 FPM until 25,000 FT
- 25,000 FT reduce ROC to 1,200 FPM until 28,000 FT
- 28,000 FT reduce ROC to 1,000 FPM until 30,000 FT
- 30,000 FT reduce ROC to 750 FPM until 30,500 FT
- 30,500 FT reduce ROC to 500 FPM until 30,750 FT
- 30,750 FT reduce ROC to 250 FPM until 30,900 FT
- 30,900 FT reduce ROC to 100 FPM until 31,000 FT
- 31,000 FT ALT CAPTURE/TOC .... target airspeed 323 IAS

Maintain full power for the following FL310 cruise performance .... and adjust engine thrust to maintain cruise MACH accordingly during flight.

-----------------------------------------------------------------------------------

B707-120 (using B707-138 1959 panel)

MGTOW 257,000 LBS.

4X P&W JT3C-6 turbojet engines rated at 11,200 LBS thrust e/a .... 13,500 LBS thrust e/a with water/methanol injection.

Activate 4 Water/Methanol Injection switches. Set maximum T/O thrust. Do not release brakes to commence T/O roll until all 4 WI anunciator lamps have illuminated .... at approximately EPR 2.55.

PLEASE NOTE: Water/Methanol injection/boost is available for approximately 3 minutes only during T/O and C/O.

Initial ROC 1,500-1,800 FPM.

After gear and flap retraction maintain full power. Increase ROC to 2,500 FPM until passing 16,000 FT. Assume the following schedule for best climb performance ....

- 16,000 FT reduce ROC to 2,000 FPM until 18,000 FT
- 18,000 FT reduce ROC to 1,800 FPM until 20,000 FT
- 20,000 FT reduce ROC to 1,500 FPM until 27,000 FT
- 27,000 FT reduce ROC to 1,200 FPM until 28,000 FT
- 28,000 FT reduce ROC to 1,000 FPM until 30,000 FT
- 30,000 FT reduce ROC to 750 FPM until 30,500 FT
- 30,500 FT reduce ROC to 500 FPM until 30,750 FT
- 30,750 FT reduce ROC to 250 FPM until 30,900 FT
- 30,900 FT reduce ROC to 100 FPM until 31,000 FT
- 31,000 FT ALT CAPTURE/TOC .... target airspeed 323 IAS

Maintain full power for the following FL310 cruise performance .... and adjust engine thrust to maintain cruise MACH accordingly during flight.

Looking at the other points you've raised now ....

2. Aircraft doesn't track on the runway properly. On take-off run it veers right as with a flat tire and requires constant adjustments to keep it on the runway.

Any of the following factors could come into play here ....

- FS isn't perfect. It may not, in some cases, load an aircraft on the the RWY centerline with precision .... and this may be difficult to detect until after commencing your T/O roll and until you may notice the aircraft slowly veering off/over the centerline. Any such movement should be very minor, if evident at all though. Careful rudder application will correct this.

- Veering off the centerline can also be caused by a fuel imbalance .... if your fuel load has been adjusted improperly prior to T/O. This will result in quite an acute angle RWY drift than described above and is most often the cause of this.

- Again .... it's also possible than any RWY drift, at all, may be the result of joystick/controller device calibration issues .... which more often than not are the cause of any RWY drift during T/O. There is also a high degree of probability that joystick/control device calibration can be causative of RWY drift. Try cycling your joystick/controller device throuigh all axis of elevator, aileron, and rudder control prior to commencing T/O.

- "IF" you have an excessively strong cross-wind component set within your weather scenarios .... then that's not going to help either and is something that will require fairly constant rudder input in to correct RWY drift during T/O.

I don't know if this might help in the case of jet flying (it probably won't, but, there's absolutely no harm in your trying this anyway) .... go to SETTINGS/REALISM/FLIGHT MODEL .... reduce to the absolute minimum just those 3 slider for "P FACTOR. TORQUE, and GYRO" only .... and then set the 2 remaining sliders for "GENERAL, and CRASH TOLERANCE" up full .... just to see if this helps resolve your RWY drift issue.

Mark C
AKL/NZ

[aerofoto - HJG Admin]

Thinking about this further .... another thing we need to be sure about too is in regard to the following ....

You must use your the B707-120 panel with the B707-120 aircraft base pack "ONLY".

Do not do what some folk have done, in the past (to try'n save space) .... in that they have apparently tried installing all of their B707/B720 files into a single aircraft base pack/container .... and then relying on a single AIRCRAFT.CFG file to try and pull everything together within FS.

I'm not suggesting you've done this, but, I want be sure it's not the case. Taking shortcuts in regard to the installation of any of these files is a sure recipe for wrong or failed aircraft/panel related performances.

Each B707/B720 class of aircraft is different both in its structural configuration and performance .... therefore these all require separate aircraft base pack files/FDE. For these, and other reasons too, most B707/B720 files also require different/separate panels as well.

If you have been unfortunate enough to "mix your files up" then this may also account for why the Water Methanol Injection system annunciator lamps in your B707-120 panel won't illuminate .... or are taking several minutes to illuminate .... simply because the panel may be configured with the wrong aircraft base pack FDE to start with.

VERY IMPORTANT .... but .... just a simple thought only !

Just a bit more on this too .... though George is probably best person to elaborate.

Those Water Injection system annunciator lamps require that a specific engine speed first be be attained before they can illuminate. I'm note sure if this engine run speed is based around EPR, N1, N2, or EGT .... but .... it "IS" a very high value which is normally only attainable by those early turbojet type engines. Again .... if you've got your panel mated to the wrong aircraft base pack/FDE .... then you might not, easily, be able to attain these very high engine run speed values .... and which will result in the lamps either not illuminating or taking a very long time to do so.

I can't think of any more to add !

Mark C
AKL/NZ

[jimhalinda]

I too have occasionally seen the water injection take its sweet time to light up all four lamps. But then other times it works fine.

I don't fly the -120 much, so I've only seen it once or twice.

But i do know there's some sophisticated programming in these panels, and other third party applications can cause problems.

For example, I have a full paid version of FSUIPC, and the weather radar uses it. It works fine.... unless I'm running Autower, a free third party app that automatically switches tower view to the closest tower as you fly. I can't have this and WX radar at the same time. Nobody's fault, just two different programmers unknowingly competing for FSUIPC resources I guess (can you tell I'm in software?)

I also occasionally have other odd behaviours that are probably caused by some combination of addons I'm using, but it's not easy to figure out what's clashing with what.

Just my two cents.

Jim

[aerofoto - HJG Admin]

I too have occasionally seen the water injection take its sweet time to light up all four lamps.

I trust your feedback Jim .... but .... only for the sake of the original posters query, it's perhaps important for me to clarify .... in case I wasn't sufficiently clear above .... as follows ....

The illumination of those Water Injection lamps is not, and is not intended to be, an instantaneous light-up reaction achieved immediately upon the setting high power .... which I suspect is what some folk are possibly thinking.

These engines do require very high power to be attained .... first .... and the JT3C6 turbojet "IS" a slow spooler .... requiring some 20 seconds to achieve full power .... with another delay beyond this duration in order for the Water Injection system to boost thrust by that additional 10-14% .... and at which point those lamps then illuminate to confirm this has been achieved.

I timed this FS response in a quick test this morning .... and got the standard response I've always seen in terms of time/duration .... and which I've quoted above.

Mark C
AKL/NZ

[parkway]

Many thanks for your very helpful comments. The problem I was having with the water injection system was in fact due to my not jamming the throttle all the way home. Once that was done, the the engines spooled up as required and the lamps lit on queue, No.1 first and then the other three together.
As far as the runway tracking problem goes, I think it is, as suggested, something to do with the weight adjustment. By not tampering with other than the centre fuel tank, the aircraft ran straight; but I am still working on this.

[aerofoto - HJG Admin]

YEP .... that's the story "PARKWAY" .... power levers all the way up .... "MAX THRUST".

That should actually be standard procedure with all of the early turbojet powered aircraft .... represented by B367-80, B707-120, B707-138, B707-220, B707-320, B720-020, KC135-A (SERIES), CV880-22, CV880-22M, DC8 SHIP ONE 1959, DC8-10, DC8-20, and DC8-30.

Only B367-80, B707-120, B707-138, KC135-A (SERIES), DC8 SHIP ONE 1959, and DC8-10 aircraft panels feature the Water/Methanol thrust augmentation system though.

All of the other turbojet series aircraft mentioned above, having more powerful engines, didn't require such thrust augmentation.

Hope that helps you understand things better

If you want a better idea of how to manage fuel loadings .... then please refer to Harerton DOURADO's excellent FUEL MANAGEMENT TUTORIAL .... which is downloadable from the BOEING PANELS page/B707 PANELS section.

Mark C
AKL/NZ

[jimhalinda]

There's my cause, Mark - I seldom push the throttles right to the max, I always try to get as close to 100% N1 without anything going into the red, so to speak. ALthough on the 707-120, depending on altitude and temperature I guess, sometimes I must have been able to use full throttle.

I agree with the legendary Chuck Yeager who didn't believe in 'reduced power' takeoffs - he wondered why a pilot wouldn't want every bit of available power for every takeoff.

Having said that, I try not to just firewall the throttles, as I worry that it isn't "realistic"... but in the case of these underpowered water wagons, I guess it's allowed! From now on I will cheerfully max out on the -120s!

Regards,

Jim

[aerofoto - HJG Admin]

I seldom push the throttles right to the max, I always try to get as close to 100% N1.

Probably the right procedure for the FANJET and TURBOFAN engines which followed the turbojets which require more care/preciosin .... but .... according to contemporary reports I'm reading (written by a retired QANTAS captain .... athough I think he's now left the launching pad and shot back into space/passed on), QANTAS pilots, flying the JT3C-6 turbojet powered B707-138 before they were all upgraded to JT3D-1 fanjets and B707-138B standard (similar to the B707-120/120B), apparently used to push all 4 thrust levers up .... "to the MAX". This retired captain states in his momoirs .... "the only thing that then needed to then be watched was the EGT's".

I guess we're now living in an age of aviation technology where these old performances, procedures, and limitations are all possibly starting to become less familiar if not forgotten with the subsequent passing of time

Mark C
aKL/NZ

[George Carty - HJG]

Firewalling the throttles is correct for JT3Cs but not for JT4A engines (707-220, 707-320, DC-8-20, DC-8-30). The JT4A's take-off EPR is about 2.55 under standard conditions.

[aerofoto - HJG Admin]

Thanks for your clarification there George

What George is stating here folks (for those interested) is that the JT4A series turbojets have quite bit more power/thrust than those of the earlier JT3C models.

And for this reason .... the JT4A series turbojets did not require the Water.Menthanol thrust augmentation of the JT3C and earlier series turbojet engines.

Mark C
AKL/NZ

[Herman]

Parkway....sorry that I am a bit late with this, but I did want to mention something regarding your tracking problem.

It is not realistic to expect an aircraft to track perfectly straight down the runway center line during takeoff or for that matter after touchdown, without taking some corrective actions using the rudder control.

There are a couple of things, other than proper equalized loading, that will effect your tracking during the takeoff run.

1. Wind direction and speed would be your major consideration.
Unless the wind is straight down the runway you will require
rudder inputs in order to keep aligned. With strong crosswinds
you also require some aileron correction to equalize wing lift.

2. Engine power settings must be equalized.

Herman