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Computing aircraft gross weight


scrapple
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To do things right, the rotation and takeoff speeds and approach and landing speeds are based on aircraft gross weight. Is there a magic button I can press in the cockpit to get the gross weight? Or do I have to compute the number using actual math? :(

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let me guess

to much PMDG 737NGX;)

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If I'm not mistaken, Mission Planner only gives initial gross weight. You would still have to do math if you started from ramp.

 

But from ramp and 30 minutes of ground operations you only burn 500lbs of fuel per the -1-1 manual, and subtracting 500lbs from you initial gross weight isn't that hard....hell I did this without even using a calculator, just the -1-1 charts:

 

UcMOD6vCPuQ

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OK, thanks for the info.

 

I can see that computing your TAKEOFF weight wouldn't be much of an issue. I assume in real life the pilot knows that number before he even gets in the plane.

 

The more difficult issue would seem to be computing the LANDING weight, since this would depend on a number of variables that you can't compute ahead of time: how much fuel is left, how many cannon rounds you have left, and how many of the various ordnance types (GBU-12, etc.) you have still hanging off the plane. Plus it would have to be computed while you're flying the plane. So, in real life does the pilot, sometime prior to landing, actually compute the gross weight by adding all this up, or do they do a quick estimate, or do they not do anything and just count on their AOA indexer to keep them at the right approach speed?


Edited by scrapple
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To do things right, the rotation and takeoff speeds and approach and landing speeds are based on aircraft gross weight. Is there a magic button I can press in the cockpit to get the gross weight? Or do I have to compute the number using actual math? :(

 

 

MLW+Enroute Burn=MTOW

 

TOW-RWT=max fuel on board to land

 

In the real world, we are given our weights on a load close out from an electronic weight and balance (EWBS). Our company mandates that we still figure our MTOW by hand and compare that with what was sent via ACARS. If no EWBS is available, then we have to do the WB by hand, so yes there is a lot of math involved. No magic button per say.

 

If you're talking fighters, if the take of trim is set, the airplane will actually begin to rotate on its own and all the pilot has to do is add a little back pressure and when there is enough lift, it will fly off of the ground.


Edited by strikeeagle

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Chris

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I also follow the AoA indexer on landing. In the video I made it was a bit of guesswork. The time/distance/fuel burn for descent requires gross weight; ok no problem. But then I find out that after my descent it puts me at ___nm from final approach, so then I have to figure out fuel burn between the time I finish my descent and get to final approach.

 

I wish there were a more detailed, real-world explanation of how it should be done. The manual can be vague at times.

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MLW+Enroute Burn=MTOW

 

TOW-RWT=max fuel on board to land

 

In the real world, we are given our weights on a load close out from an electronic weight and balance (EWBS). Our company mandates that we still figure our MTOW by hand and compare that with what was sent via ACARS. If no EWBS is available, then we have to do the WB by hand, so yes there is a lot of math involved. No magic button per say.

 

If you're talking fighters, if the take of trim is set, the airplane will actually begin to rotate on its own and all the pilot has to do is add a little back pressure and when there is enough lift, it will fly off of the ground.

exactly what the man says

;)

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Hit Alt ' to bring up the reload screen

There you will find the max load weight and actual.

Why not do the same thing the real life pilots probably do? Let the crew chief figure it out. :music_whistling:

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Hit Alt ' to bring up the reload screen

There you will find the max load weight and actual.

Why not do the same thing the real life pilots probably do? Let the crew chief figure it out. :music_whistling:

 

That's takeoff weight though, which is easy. How about your weight after you've flown around a bunch, shot off some rounds and dropped some bombs? That's a bit tougher :)

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Just fly the airplane. The A-10C was not certified under FAA regulations as a commercial aircraft. This aircraft was built as a combat attack aircraft, not a penny pinching, FAA/lawyer number satisfying aircraft. rotate at 150 and land at 150.. that should do it, one pilot, not much gas, i have never had a problem. Numbers do not make it fly, a pilot does. Do you understand what a pilot is?

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Land at 150? Try that at Batumi with a wet runway and you won't stop in time. AFAIK you're supposed to fly the AoA indexer, which will put you at correct approach/landing speed, which varies based on gross weight.

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Numbers do not make it fly, a pilot does. Do you understand what a pilot is?

 

Said no pilot ever.

 

There is great info to be found on these forums which has helped me get up and running with the A-10.

 

Sadly though, there is some seriously stupid stuff like the above scattered around.

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MLW+Enroute Burn=MTOW

TOW-RWT=max fuel on board to land

 

Huh?

 

"Anyway, moving right along.."

 

Take-off weight = Ramp weight - Taxi fuel (incl. APU burn). 500lbs. Seems like a reasonable estimate in most cases.

Landing weight = Take-off weight - Fuel used - Stores expended

 

It's not rocket science...


Edited by chaos

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Huh?

 

"Anyway, moving right along.."

 

Take-off weight = Ramp weight - Taxi fuel (incl. APU burn). 500lbs. Seems like a reasonable estimate in most cases.

Landing weight = Take-off weight - Fuel used - Stores expended

 

It's not rocket science...

 

 

What, you don't agree with my math? I have to compute MTOW for every flight. My company and the FAA mandates it. Besides, I thought he was talking about some other sim.

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If the A-10A's -1-1 is anything to go by, you're supposed to have everything planned out, but it looks way too dogmatic to me. What if you come home with ordinance left? Or more fuel than planned? I don't see much mentioned in regards to variables like these, and it's not like the pilot can whip out the manual and a ruler to check his performance charts while flying home...

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Wow, a 2 page thread for something so simple?

 

Rotation & take off speeds are calculated using mission planning software. And there are a few applications made for DCS that will do this for you. Flaming Squirrel provided a link to one such program.

 

But a rough rule of thumb is 110 knots + 2 knots per 1000 lbs above 25000 lbs. So 130 knots at 35000 lbs, 150 knots at 45000 lbs. Rotation speed is 10 knots below takeoff speed.

 

Approach speed is simple mental arithmetic.

 

25,000 lbs + fuel + ordnance = gross weight

 

Approach speeds are just as easy to calculate.

 

110 knots + 2 knots per 1000 lbs of fuel/ordnance for full flap approach speed

120 knots + 2 per 1000 lbs of fuel/ordnance for no flap approach

145 knots + 1 knot per 1000 lbs of fuel/ordnance for single engine approach

 

Spoiler

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Only simple if you know about it. From the looks of things those "mental arithmetic" shortcuts aren't mentioned in the manuals and only taught orally by people who are in-the-know.

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They are not exactly shortcuts, the approach speed calculations I wrote above are exactly what the charts say just in text form. And the takeoff rule of thumb is just rounding up the numbers on the chart so it's easier to do in your head.

 

Nothing that couldn't be worked out by anyone bothering to read and understand the performance charts from the -1.

 

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Are the speed calculations mentioned anywhere in the -1, or is it up to the individual to extract that data from the chart? I didn't see it in the -1 (only the charts) and I seem to have missed my college math class where they taught us how to extract data from flight performance charts...

 

One of my big gripes with any of the high-fidelity sims--DCS and BMS-- is that if you want to do things right, there isn't a whole lot of information out there written down. Sure you have the DCS A-10C manual, but that just covers the basics. Then there's also the real A-10 -1. But if you don't have the required aviation knowledge to "work out [something] by bothering to read and understand the performance charts" you can't. No matter how many times you read or re-read it you just won't get it. And that required knowledge seems to only be available to people lucky enough to have actual flying experience or know someone who has said experience.

 

I have tried to read and understand the performance charts and I simply can't because I do not have that required knowledge. The only thing I can do is work out a problem using the charts and given variables.


Edited by Nealius

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Mines easy. I don't usually land with ordinance. If I have a bomb or 2 left when I return it's usually because I'm damaged. That's what the little red button is for :thumbup:.

Even if you aren't damaged, it's not necessary to bring the bombs home. They're free so chuck them.

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