Minimum throttle limit

[Stanley777]

Hi everyone,

 

I cannot recall where I read this. Wherever it was, someone commented that the "minimum throttle limit" --which, as you may know, controls the amount of reverse thrust -- is typically set too low by default in the aircraft.cfg file. This person noted that the usual amount of -0.25 is not low enough. A more realistic number would be in the range of about -0.35 to -0.55 (or numbers around that, I don't remember exactly).

 

I took up this person's advice and have started to change this setting in my aircraft.cfg files to be -0.45.

 

So, is this correct? Should the value in min_throttle_limit be made more negative thatn -0.25?

 

Thank you.

 

Stanley

[mallcott]

Doesn`t sound correct in wither case.

[Stanley777]

Hi mallcott,

 

Thank you for your reply.

 

By default, the value is -0.25. Are you saying that that value is incorrect, or that any value between -0.35 and -0.55 is incorrect?

 

Stanley

[napamule2]

There is no 'incorrect' value. You use the value that gives you the result you want. Or at least you can hope it does. What is missing here is the relationship with the air file entry (section 313 of 1101 (Flight Dynamics) section. If section 313 is missing your adjustment will 'fall back' to DEFAULT reverse thrust. To make adjustments you need section 313 and set it ('Reverse Thrust)to = -50'. Then the value in aircraft cfg will 'take'. -0.25 is usually the default, even for the F-18. With a value of -0.39 you get more reverse thrust. With a value of -0.55 you will be backing up '0 to 60' in 6 seconds - something you might not want - of course (but can 'use' with Lear Jet?). For the heavies, that high value (-0.55) might afford you quicker stopping 'power' if you are landing on a (too) short runway, or with a heavy load (ie: C-130 at North Pole and on ice runway). Not documented anywhere. Talking from experience. Ultimately YOU control how much reverse thrust is 'used' (ie: by how long you hold down the F2 key or panel levers). So the value 'helps' but can't 'hurt' ALL BY ITSELF or ON IT'S OWN. Capiche? Comprende? Multe Bueno. Chao. Adios. Arividerchi. Cheers.

Chuck B

Napamule

[Stanley777]

Hi Chuck B,

 

Thank you for your most instructive reply.

 

Now, I have not made an exhaustive review. From a preliminary inspection, however, not even one of my default FSX Steam Edition aircraft has Section 313 entitled "Reverse Thrust Throttle Percent = -xx" in their respective .air file. On the other hand, of the third-party aircraft that I have so far searched, every one of them does have that line.

 

(Incidentally, I am not seeing that line within 1101, but as a standalone line.)

 

But I don't understand this issue. Let's say that Section 313 were present and it said, for example, "Reverse Thrust Throttle Percent = -25". Then, if you changed the line in the aircraft.cfg file to -.40, which reverse thrust power would you be getting -- 25 percent or 40 percent?

 

I will be on vacation for a few days. So I look forward to reading your response, but I will not be replying right away.

 

Thank you.

 

Stanley

[mallcott]

.air file is modified by .cfg file

 

But the fundamental error is in thinking that ANY aircraft engine can deliver more then 25% of its total thrust in reverse.

It can't. No prop, no jet. Nothing.

 

The simplistic notions of the .cfg file represent total thrust in the opposite sense to the normal direction - that is to say backward.

 

The technical explanation is probably beyond you and discussion in this topic, but that 0.25 represents a summary of the directional thrust available in direct opposition to the normal thrust line of the engine - prop or jet. No jet can fully reverse its flow, and reverse thrust is provided by buckets or vanes that redirect the thrust out the back end - so the flow is not reversed through the full 180 degrees, but usually little more than 90, so the effective thrust in reverse is a consequence of some forward thrust from the engine, less the impact of the reversed flow, adjusted by the angle. for props, the prop only provides efficient thrust in one direction.

 

So whatever you're trying to `fix` it's based on flawed logic. You can do what you want as Napamule says, it's your sim, but it's just plain wrong.

[napamule2]

You can leave the 'real' discussion out of this as we KNOW Sim reverse thrust is not as 'real'. No 'logic' is involved here either. It's pure mechanics. And it's not wrong. What is wrong is that MS did not finish the job on a LOT of things. The fix is not in the model but related to the cfg and air files. So fix we must.

 

All we need is sufficient information to not mess it up but improve it as much as is possible.

 

You have any objections about doing that? So I guess it's also 'plain wrong' to tweak the contact points because that is not how it's done in 'real'? You got any 'technical explanation' about doing, or not doing, THAT operation (also mechanical)?

 

You would do what? Require a math formula to 'dial in' the wheel size, thread composition, and/ or tire pressure variations, along with atmospheric temp and pressure thrown in for good measure before ALLOWING us to make any changes to cnt pts? You would, wouldn't you. Cheesh!

Chuck B

Napamule

PS: Stanley, I goofed on 313 being inside 1101. It's a 'Gray Matter' problem (hehe).

[mallcott]

Actually, I`m not even sure that the .air files elements you refer to are even read in FSX.

Perhaps you`re confused by the difference between FSX and FS2004. That old grey matter, eh?

 

Merry Christmas.

[napamule2]

Please, PLEASE, PLEASE! be more specific. You are saying (that you KNOW) that section 313 in air file is NOT READ by Sim engine? Really? How did you determine that? Or, are do you just wanting (to fix it with your mouth) and thus make it 'LOOK' like you (actually) know what the hell you are talking about. Air file elements? Section 313 can be in both FS9 and FSX air file. So I suppose because MS left section 313 out that THAT is how you 'gather' that it is not 'read' by Sim. Does not compute. You don't even know how to edit the air files do you? It don't sound like it TO ME. Others might believe you know everything about the air files. But making assumptions won't work (with me). So I say you are 'full of it' so bug off. And your (blatant) statement: '.air file is modified by .cfg file' is TOTALLY FALSE!!! Why do you do that? To annoy people? Not very 'professional'. Go soak YOUR gray matter.

Chuck B

Napamule