A10C engine model

[bkthunder]

I dunno. I still dont know if there really is an issue. If we have something modeled by documents ED had, then its really not an issue.

 

What the discussion is pointing at, is that the documents ED used to model the engine refer to engine performance when the engine is NOT installed on the airplane.

 

So the numbers in the sim match the data posted by Yo-yo, but the data posted by yo-yo refer to an uninstalled engine.

 

There are several documents that have been referenced, in which SOP indicate that ITT temps are higher than the ones we have, and these are not classified.

 

 

I understand, we are missing the numbers in between, like fuel flow, Nf etc, for the installed engine, but I agree with what Kansas CS said. We are raising a fair and IMO well documented concern, it should be ED's job now to hunt for all the specific info they need to refine the engine model. Of course if the community is able to find such info, then they should be provided to ED, but this shouldn't be only a responsibility of the community.

Edited August 13, 2016 by bkthunder
Bloody iPad "auto-correct"....

[KansasCS]

Obviously no one has the pedigree and volume of data needed for Yoyo. That doesn't mean it isn't out there and probably a lot easier to get a hands on by employees of ED, who have the license to model the hawg. Or was the data given a one time glimpse, never to be updated?

Of course they have a lot on their plate, no one is denying this or putting ITT numbers above any other project going on.

But the fact that this discussion is still going and was reopened sort of hints at the possibility that the engine code is off a little. Why else discuss it if it has been proven otherwise?

What is stopping ED from acknowledging a deviation, jotting it down on a list of lesser important stuff and following up on it when permissible?

 

 

 

 

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[David OC]

I agree, ED could definitely look into it down the track if more information presents itself and perhaps perfect it... For now you could rewrite the procedures as they do IRL to suit this simulation at hand which is, not in real life. The simulation certainly does make my heart beat faster tho, even if it is only a simulation.

Edited August 13, 2016 by David OC

[majapahit]

If the A10c feels underpowered, especially loaded and when climbing out of a bomb run, is what I think to experience,

 

perhaps with all this number crunching in this thread here, perhaps it is not the simulation of the engines power rating where a lot data is available or perhaps reasonable estimations can be made,

 

perhaps it is an error in the drag factor of the load out, the calculus of this or the simulation of this.

 

These days I simply fly (with limited time window available) with ‘unlimited ammo’ setting and then load as little possible, flies way better.

 

?

[KansasCS]

If the A10c feels underpowered, especially loaded and when climbing out of a bomb run, is what I think to experience,

 

perhaps with all this number crunching in this thread here, perhaps it is not the simulation of the engines power rating where a lot data is available or perhaps reasonable estimations can be made,

 

perhaps it is an error in the drag factor of the load out, the calculus of this or the simulation of this.

 

These days I simply fly (with limited time window available) with ‘unlimited ammo’ setting and then load as little possible, flies way better.

 

?

That is a), not realistic and frankly quite unsatisfactory for a lot of people and b), beside the point.

Yoyo, or any other dev for that matter won't change flight models based on feeling. Only hard evidence.

But just because that evidence is incomplete, doesn't mean it's wrong.

From what I understand, various sources that have since been deleted in this thread cite higher temps as the norm, whereas Yoyo's documents do not.

If, as sithpawn said, it is up to the community to come up with solid and comprehensive sources that prove the current modelling is wrong, then I guess we are at an impasse. Crewchiefs, pilots and manuals can state ~865°C all they want. If it's not a comprehensive datasheet that states every last parameter, it will be most likely disregarded.

[Buznee]

Just a note. At least on the civil side engine performance and therefore aircraft performance charts for turbine aircraft are based off of minimum guaranteed "specification" installed thrust/power by the engine manufacturer. A new engine will develop higher thrust/power for a given ITT engine limit. As the engine is utilized it degrades in performance due to many losses such as erosion of the blades, increase of blade tip to shroud clearances, degradation of material properties, bearing wear, and engine abuse. This causes a reduction in the the thrust/power for a given ITT. During the design and requirements definition phase, the aircraft manufacturer will ask the engine manufacturer to guarantee a minimum specification power for a certain set of conditions in the proposed flight envelope. Once the engine is installed on the aircraft, the achieved installed thrust/power and installed losses are quantified by the aircraft manufacturer in the testing phase and confirmed to have met the requirements (or not). This data, normalized to the minimum specification power, is utilized to develop the performance charts in the flight manual. Therefore what you see in the charts is most likely based off of minimum guaranteed power/thrust. You would hope that the actual aircraft performance with healthy engines should be better. On the sim side this would all depend on the modeling of the engines. For example on the huey there is an option that allows you to increase the engine health in percent which simulates and engine that provides greater power for a given ITT.

[KansasCS]

There is no chart in there illustrating ITT as a function of throttle lever or rpm.

It just says that in emergency fuel flow override, the engine can reach a higher thrust but also heats up and should be maintained below 865°C.

That is it.

[SkateZilla]

Do NOT post links to Classified Manuals.

Edited August 14, 2016 by SkateZilla

[millmax]

I've ejected, and my wingmen have ejected, while flying in canyons in enemy territory after loosing one engine. Even with stores jettisoned you'll have a really hard time trying to climb a mountain pass up ahead. Being able to override fuel flow and gaining thrust would be of tremendous use for us, even though it might lead to an engine write off after landing (depending on the temperatures reached during override, of course).

I hope this illustrates a real world example that members would appreciate implemented, even though A-10 might have a feature complete status.

[NineLine]

Do NOT post links to Classified Manuals.

 

And just to be clear on the whole document thing... ED knowns how to use the internet, they are looking for stuff beyond what you can find on the net, that goes with any aircraft they work on...

[Raistlen007]

And just to be clear on the whole document thing... ED knowns how to use the internet, they are looking for stuff beyond what you can find on the net, that goes with any aircraft they work on...

 

Can you please clarify what we could submit that would be helpful?

 

If we can't link to any USAF document because they're "classified" and ED can see them anyway... and HUD video is dismissed because "you can't recreate the exact conditions" and A-10 pilot input is dismissed because "muscle memory is not a substitute to data" and expertise of ground crew is dismissed because "not hard data"...

 

I would seriously, no sarcasm, like to know what would be helpful here?

 

Because right now I feel like this is an artificially constructed catch-22.

[Enduro14]

Can you please clarify what we could submit that would be helpful?

 

If we can't link to any USAF document because they're "classified" and ED can see them anyway... and HUD video is dismissed because "you can't recreate the exact conditions" and A-10 pilot input is dismissed because "muscle memory is not a substitute to data" and expertise of ground crew is dismissed because "not hard data"...

 

I would seriously, no sarcasm, like to know what would be helpful here?

 

Because right now I feel like this is an artificially constructed catch-22.

 

+1

[NineLine]

Can you please clarify what we could submit that would be helpful?

 

If we can't link to any USAF document because they're "classified" and ED can see them anyway... and HUD video is dismissed because "you can't recreate the exact conditions" and A-10 pilot input is dismissed because "muscle memory is not a substitute to data" and expertise of ground crew is dismissed because "not hard data"...

 

I would seriously, no sarcasm, like to know what would be helpful here?

 

Because right now I feel like this is an artificially constructed catch-22.

 

Actual testing data, wind tunnel testing, actual engine manuals with all parameters needed for the FM, generally most stuff you wont find on the internet. Stuff that would help you recreate the engine generally dont float around on the net. Companies dont like sharing that with anyone, specifically if that anyone is say a competitor for military contracts. Generally ED would have to sign some sort of NDA I would imagine to get this data... not just google it.

 

Pilot info and videos are ok to an extent, but without knowing all conditions, it can be a lot of guessing. A-10 pilots are not dismissed, but going from the real thing to a simulator with plastic controllers and no real feeling of flight can make the FM feel very different to them. A F-15 pilot was instrumental in working the F-15 PFM, but he worked along side ED employees to get the best info out of him, and he flew the FM a lot.

 

SO no sarcasm, but most of us wont be able to get ED anymore than they can get themselves, and those that can, probably are not allowed to share it. Let me know if I need to explain that better, hope that made sense...

[KansasCS]

So why have a bug thread on flight performance?

No one can tell if something is off and the ones that do tend to lack the data or the rights to prove their claim.

 

 

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[jester_]

So why have a bug thread on flight performance?

No one can tell if something is off and the ones that do tend to lack the data or the rights to prove their claim.

 

+1

 

In my experience, anything anyone submits as evidence for a change or even just a review is "not evidence" or "not valid" for whatever bizarre and extraneous reason here.

[NineLine]

So why have a bug thread on flight performance?

No one can tell if something is off and the ones that do tend to lack the data or the rights to prove their claim.

 

 

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Because if I don't allow these discussions I am the evil dark Lord of censorship, but when I do I get comments like jester who obviously didn't read anything I said, or understand it at least... So on that note....

 

Closed.