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JohnsonPBX

How symmetric is thrust when hand flying?

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Hello. Just purchased the Queen yesterday morning and even though I haven't had the time to properly fly her (was in a rush to go to work and only tested her for like 10 minutes, and then when I came back home I just did a circuit at my local aerodrome because I've been more into reading the introduction and forum topics), the very few minutes I had with her majesty were just royal. Sound is amazing and performance-wise it's a joy.

 

The very moment when the aircraft first initialized immediately brought me back to the first time I loaded the 747-400X on my very first, very low-end computer and it would barely reach 10FPS on a default scenery... I was like "please, not again" but bam, I was glad to realize that those days seem to be long gone for good.

 

Now to the point: I have a Saitek Pro Flight Yoke, with its throttle quadrant, plus an additional throttle quadrant for quad-engine configuration. My plan is to use the outer levers, left and right, for spoilers and flaps respectively, and then the inner ones (two from each quadrant) for engine thrust levers.

 

I noticed that in one of the quadrants (the one I bought separately) the inner levers, which are supposed to be engines 1 & 2, are not properly synchronized with engines 3 and 4, located on the other, included quadrant. That is something I will have to find a work-around for (maybe cleaning its potentiometers and try and calibrate via FSUIPC, tips are accepted).

 

This then led me to wonder, how symmetric is thrust when a pilot hand-flies a 747? Keeping in mind that he has to control all four levers with one hand, and due to its shape all four levers will not be exactly alligned at all times. Will there be a slight discrepancy among each engine, does the thrust system have a mechanism to link all levers and move them exactly together or does the plane/system automatically correct any offset?

 

Thank you in advance for your replies!

 

Offtopic: I don't know if anyone mentioned it already, but did anyone notice the visual effect (don't know what it's called) of hot air blowing out of the engine nozzles? Maaaan...

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Document on using FSUIPC to sync multiple throttle levers here:  http://fsuipc.simflight.com/beta/CALIBRATING_MULTIPLE_THROTTLES_etc.pdf

 

There's also a hotkey in FSUIPC that will sync all the throttles to the value of lever #1. 

 

In the r/w, the throttles have a much longer throw than most joystick throttle quads, so a little misalignment of the power levers isn't too big a deal.  There's no linkage that keeps them together--you grab a heapin' handful of throttle and work 'em.

 

But...the percentage of time the throttles are on A/T in a B744 is probably in the high 90s...ground ops and landings are the only time the A/T isn't engaged in a normal flight.  I've got a few thousand hours in the old C-141 Starlifter...our A/T system only worked at cruise, so we manhandled those big power levers a lot.

 

Regards

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Hello Bob,

 

Thank you for your response! Now everything is more clear to me. I tried the document you highlighted and the results were pretty satisfactory. Nonetheless, on my Saitek throttle quadrant (separate unit) there is a lot of axis spiking, which means that sometimes the calibrating (Sync position) tool doesn't work as intended, as the output of the lever movements is always different on every full up/down cycle.

 

Tonight as I get back home I will try and clean the potentiometers, well know to be bad quality from Saitek.

 

Anyway I've had both units for almost 5 years now and never cleaned them, so I'll see how they behave after a cleaning.

 

Thanks!

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I've got a few thousand hours in the old C-141 Starlifter...our A/T system only worked at cruise, so we manhandled those big power levers a lot.

 

I knew I liked you, didn't know you flew the C-141.  I fell in love with her immediately on my first assignment as an E-2 at Norton AFB (San Bernardino International now) in 1968.  My security clearance was still in the works so I got temporarily posted as an maintenance helper at the GCA trailers a few hundred feet from the runway.  Needless to say it was a very busy time, and I loved it.  I later flew on a couple getting free "space-A" rides around the country, and finally able to fly the C-141 simulator at McChord AFB WA months before I started USAF-funded college and commissioning.  She was a beautiful aircraft.  That time in the GCA trailers cemented my love affair with all things aviation.  My detour occurred in college when I failed the eye test so I became a private pilot instead of an Air Force Trash Hauler.

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Hey Dan...yup, I was at Norton for five years.  When we first moved there, we stayed in the TLFs near the approach end of 06...couldn't have been more than 1000 ft from those GCA sheds.  Still remember getting woken up at 0600 that first morning by the low rumble of the daily 807 departure.  I knew that grand old bird well, both as an IP and as a maintenance officer in a MAC cross-flow program.

 

In 2007 I was attending a regional conference hosted by 12th AF HQ at Davis Monthan AFB in Tucson, and one of the perks was an executive tour of the AMARC (boneyard).  Driving in the back gate, one of the C-141s that had been assigned to my OMS flight--red Norton tail flash still affixed--came out the other way on three flatbed trucks after having been guillotined for the smelter.  I will admit to watering up a bit over that.

 

Cheers

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In 2007 I was attending a regional conference hosted by 12th AF HQ at Davis Monthan AFB in Tucson, and one of the perks was an executive tour of the AMARC (boneyard). Driving in the back gate, one of the C-141s that had been assigned to my OMS flight--red Norton tail flash still affixed--came out the other way on three flatbed trucks after having been guillotined for the smelter. I will admit to watering up a bit over that.

 

Heck, I just teared up with you.

 

My last assignment was a Chief of Logistics with a combat communication unit that belonged to 12thAF and I was at Davis Monthan several times, this was just before Desert Storm so it was late 1980s.  I got a nice tour of the boneyard. Later in life I flew the C-414 Chancellor into KTUS and became a tourist in Tucson. What a great place to spend a long weekend or even a week.

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Note that the plane has an engine trim feature. Basically, if AT is armed and 4 levers are quite close then all N1's are internally aligned to the highest one. We modelled this.

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Note that the plane has an engine trim feature. Basically, if AT is armed and 4 levers are quite close then all N1's are internally aligned to the highest one. We modelled this.

Just curious if you guys modeled that all engines aren't built the same so they all have different thrust?

Haven't had a chance to RTFM yet

 

Shane

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Of course. Different performance, different databases for v-speeds, altitude etc etc etc.

 

You can find out by say observing climb rates, same speed same weight.

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Of course. Different performance, different databases for v-speeds, altitude etc etc etc.

 

You can find out by say observing climb rates, same speed same weight.

Very cool! 

 

shane

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Note that the plane has an engine trim feature. Basically, if AT is armed and 4 levers are quite close then all N1's are internally aligned to the highest one. We modelled this.

 

Where is the full name?  :wink:

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Note that the plane has an engine trim feature. Basically, if AT is armed and 4 levers are quite close then all N1's are internally aligned to the highest one. We modelled this.

That's a nice feature! Thanks for letting us know.

 

Going a little bit off-topic, I was supposed to disassemble my Saitek Throttle Quadrant (separate unit) in order to clean its potentiometers and thus eliminate axis spiking. I did manage to clean them, but in the process of disassembling I accidentally removed some wires. Asked my uncle to help me solder them back, he did but as I didn't pay attention to the soldering pattern beforehand, now two of the axes are inverted, LOL. It's been very tricky but the solution is easy. Tonight he'll re-arrange the wires and I should be all set to go.

 

Therefore, I haven't been able to properly fly the queen as I'm trying to sort hardware out first. I have been, however, reading the introduction (only 30 pages left now) during my spare time at work. Once I finish, I'll start reading the tutorial. Hopefully by tonight I'll have everything ready to start enjoying the power of those four engines; I'll let you guys know how it goes.

 

Thank you for your replies!

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In the real world aircraft, he EEC's synchronize the throttles when misaligned.

The difference between the throttes may be as much as 1 knob, that is the round knob on top of the levers which the pilot keeps his hand on. Only Quasimodo has hands that may keep the throttles more misaligned, so it should do for all other pilots.

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