[NOT ACCRUATE STATEMENT] thrust-to-weight ratio is below 1

[prof_laser]

Latest Open Beta. No Mods. Track attached.

 

The Viper is known to have a TWR > 1 (one of its selling points, according to the shop). I tested this with a Viper, no external stations, all pylons removed, fuel set to 15% and enabled unlimited fuel. In this configuration, flying roughly at sea level with 200 kts (and default meterological conditions), then going full afterburner and pointing the nose straight up, the aircraft does hardly accelerate (read: not at all).

F-16C TWR test.trk

[Rainmaker]

Are you comparing this to an EM chart from a flight manual or a marketing statement?

[prof_laser]

http://www.deagel.com/Propulsion-Systems/F110-GE-129_a001736003.aspx

 

Thrust of the used engine: 29,000 pounds.

dry weight of the F-16C in-game: 20,192 pounds.

[Rainmaker]

Yep, you are going about your “theorized testing” in many of the wrong ways. That’s not really how that works.

[Quid]

http://www.deagel.com/Propulsion-Systems/F110-GE-129_a001736003.aspx

 

Thrust of the used engine: 29,000 pounds.

dry weight of the F-16C in-game: 20,192 pounds.

 

Engine thrust is highly dynamic. Sitting on a stand, it's a lot higher than when you drop it into the aircraft and it's trying to suck air through a small inlet. For that matter, thrust increases as airspeed increases, and decreases as altitude increases. It is also affected by variable inlet designs, the angle of attack (disrupting/decreasing airflow, etc.) If you think you're going to get a 1:1 T/W at 30,000 feet at .9M in a Viper, you're dreaming.

 

There's an open-source document about the F100's performance from the 2008 International Congress of the Aeronautical Sciences which should give you an idea of how thrust varies, including a chart showing thrust from sea level to 50,000 feet and .6M-2.0M. The F110 isn't going to be the same, but the same principles apply:

 

http://www.icas.org/ICAS_ARCHIVE/ICAS2008/PAPERS/286.PDF

 

tl;dr, you're not even remotely going to have a 1:1 T/W at all points in your envelope, even in an F-16.

[prof_laser]

Hey, thanks for the explanation. Although, your explanation doesn't really correspond to the testing conditions (see track file). It's not FL300 at mach 0.9. While I totally get that TWR depends on the momentary state of the aircraft in the air, the test is so stripped down (empty A/C, sea level), that it doesn't seem plausible to me that it won't accelerate (EDIT: under the conditions mentioned).

Edited October 4, 2019 by prof_laser

[Quid]

Hey, thanks for the explanation. Although, your explanation doesn't really correspond to the testing conditions (see track file). It's not FL300 at mach 0.9. While I totally get that TWR depends on the momentary state of the aircraft in the air, the test is so stripped down (empty A/C, sea level), that it doesn't seem plausible to me that it won't accelerate.

 

The point is, you've leveled a complaint that your jet isn't always at 1:1. That document shows that you will not always have a 1:1, that "static thrust" is meaningless, and your complaint is based on a misinformed concept about how aircraft and engines function.

[Sn8ke_iis]

OP,

I get what you are saying and that it might be counter-intuitive. I think you are confusing the physics of a rocket engine with an air breathing jet engine. The compressor blades can't produce the thrust you want at that altitude and airspeed. It won't be constant like a rocket.

 

For the effect I think you are looking for: take off, clean up the gear, accelerate to about 350 or so at normal take-off 8-12 degrees. Then you can kick on the burners, give them a couple seconds to ignite and the nozzles to position properly, then pull back to 60+ degrees and she will climb like a rocket.

 

:pilotfly:

[Strikeeagle345]

This makes sense considering you aren't getting the full thrust from the engine. We aren't hitting full AB.... See below.

 

The jet isn't hitting full afterburner. Nozzles are hitting 40% instead of 95%, fuel flow is at a 1/4 of what it should be, rpm is at 100% -101% instead of 105%-107%.

 

Can't sustain a 9G turn either. There is an issue. I reported this in bug and they moved it to controls issue. But this is happening across all controllers.

 

Link to report: https://forums.eagle.ru/showthread.php?t=250824

[Strikeeagle345]

update:

 

CVW-11 did some testing against the performance charts and it seems accurate. The things I noted above seem to just be off from what they should be in full AB.

[BlackLightning]

I don't own the F16 module but I like physics and I'd like to give you my .02.

 

According to this simplified model, if thrust/weight>1, then you can accelerate vertically and it seems to me that the OP is keeping this model in mind when he states that he expects the F16 to gain speed vertically.

On the other hand, we all know that horizontally, like you can see in the picture linked above, thrust works against drag and I see no reason for which drag shouldn't affect vertical speed, too.

So, I think that if thrust/(weight+drag)>1, then you can accelerate vertically.

 

It also seems sensible to me that thrust depends on the conditions. I expect speed to put air into the engine with higher pressure and so I think that the higher the speed, the higher the thrust (maybe things change in the transonic and supersonic ranges). There are supersonic prototipes which can work with just ram air! Air density affects thust, too, because the denser the air, the more oxygen it contains. On the other hand, air dansity and speed affect drag, too...

[gitbse]

It's a known problem, discussed in other threads. The engine is only burning ~~1\3 of what it should at full wet power. Seems it's only getting to full milk, or stage 1 ab.

 

Which totally makes sense from the few hours I have in it so far. It will not have near 1:1 without full AB, but it's still damn fast. Sp, its gonna be scary when properly tuned.