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eurofighter typhoon

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Re: eurofighter typhoon

Postby Algernon » Mon Sep 27, 2010 11:38 am

DFaber wrote:Great, I hope to try this soon. Additionally I like to collect yours and algernons (both really excellent) work and put it in Git sometime this week. This will replace the previous one and I will do some renaming. Please use this one for future development. Many thanks to you all.

No, thank you! :)

I haven't had much time to look at the aircraft as weekends are the busy time for me at work, but if we're committing changes to GIT and working towards a release, I am going to tweak the autopilot's altitude modes as at the moment, the pitch at which it changes altitude is too great and this causes inaccuracy at low speeds (a particular problem for the already difficult Auto Approach function).

Almursi has kindly merged together some old and new sounds, there are a few that need to be replaced, mainly landing gear, originally from Seahawk I believe - I intend to make this more subtle (as I imagine it would be in a modern aircraft). The sound of the gear will be less important once the gear indicator in the cockpit is working I think.
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Re: eurofighter typhoon

Postby Algernon » Mon Sep 27, 2010 3:30 pm

My work on the electrical systems and sounds are all now leading me towards the point that I really want to think about shutting down/starting up the engines. But I understand YASim does not natively support this, from looking at other YASim aircraft the N1 and N2 properties - which many other systems in the aircraft use - do not go below their preset idle speeds. But I really really want to be able to start the engines from scratch, so I'm wondering how we could do it.

I'm guessing a Nasal engine management system which overwrote the engine's properties during engine start-up/shut-down would be rather too hackish...?
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Re: eurofighter typhoon

Postby HHS » Mon Sep 27, 2010 3:48 pm

Algernon wrote:I'm guessing a Nasal engine management system which overwrote the engine's properties during engine start-up/shut-down would be rather too hackish...?


It would be maybe too hackish, but that's not your fault!

If I compare YASim with JSBsim I see JSBSim is far further in many things especially regarding engines simulation, and developement is still going on. While YASim.. well.... :(

The problem is, that it may be that you not only has to hack a engine management ( which is o.k., as the modern engines uses FADEC anyway, an own system), but all other related systems as well.
Fuel system, engine oil etc, etc....

For Helis I see the only way by simply completly rewrite a whole engine in nasal as solution....
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Re: eurofighter typhoon

Postby Algernon » Mon Sep 27, 2010 4:48 pm

HHS wrote:If I compare YASim with JSBsim I see JSBSim is far further in many things especially regarding engines simulation, and developement is still going on. While YASim.. well.... :(

Yeah, this is what I'd gathered from my research too. I have been working on the assumption that it's virtually impossible to get accurate enough information on an aircraft as current as the Typhoon to create a JSBsim FDM, because the information is classified. If this is indeed true, it doesn't leave us many more options.
The problem is, that it may be that you not only has to hack a engine management ( which is o.k., as the modern engines uses FADEC anyway, an own system), but all other related systems as well.

I will look into the possibility of a FADEC system, that I do not imagine would be too tricky (as I would only make in complex enough to support the aircraft's instrumentation for now) although as you say, I'll also certainly have to model fuel management, oil temps/pressures etc. too... What does everyone else think?
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Re: eurofighter typhoon

Postby Johan G » Mon Sep 27, 2010 5:10 pm

I've sometimes wondered about the possibility of having some generic nasal code for engine simulation (mainly for YAsim). It would be nice with a few variants (props, turboprops, turboshafts, jets and rockets) as a base to connect modular subsystems to like electrics, hydraulics etc.
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Re: eurofighter typhoon

Postby Algernon » Mon Sep 27, 2010 5:24 pm

I would really like that, not least because a pet wish of mine for our Eurofighter is to have zero hydraulic power when engines (and APU) are not operating, resulting in the canards drooping forwards (as in real life) - presumably, a simple script to disconnect flight surfaces from the FDM and move them to parked positions when hydraulic pressure decreases could do this.

I say 'simple' with a healthy degree of optimism!! ;)
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Re: eurofighter typhoon

Postby HHS » Mon Sep 27, 2010 5:27 pm

The concorde already has nasal scripts which should do nearly exactly the same.
But I have never seen it yet working. But it is worth a look.
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Re: eurofighter typhoon

Postby DFaber » Mon Sep 27, 2010 6:18 pm

Algernon wrote:I'm guessing a Nasal engine management system which overwrote the engine's properties during engine start-up/shut-down would be rather too hackish...?


No it isn't. A modern (and also not so modern) Aircraft engine is far too complicated for a FDM to cover all use cases and possible techniques. A piston engine can be liquid cooled, air cooled, even convection cooled, cooled by airflow over cylinders controlled by cowl flaps, cooled by airflow provided by a fan, ....
Cylinders can be in line, radial, double and triple radial, 4 -12, even 24 cylinders in double rows or two engines coupled by a gear working on one shaft.

Jet engines can be started by APU. The first jets were started by a motorcycle engine, later by compressed air.

All these cases cannot be provided only by FDM. There will always be the need to create special code, either in cpp, or Nasal. Well, I prefer Nasal. The Bf109 and F4U use a nasalized engine managment, calculating various engine parameters every 0.2 seconds (Cylinder head temperature, oil temperature, coolant temperature, more to follow) and it kills the engine if any of these are not healthy.

Creating a nasal engine startup sequence for the eurofighter (and other jets) is logical, not hackish. You have my full support, Algernon


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Re: eurofighter typhoon

Postby almursi » Wed Sep 29, 2010 6:47 am

Hi, It seems that I'll be back to have some free time, and what I see is that it take a while to tune the contributions. Especially because I have enough work still pending in the cockpit, to finish the landing gear stick/status lights, hook and canopy (at least). So it take even a few days to have it ready and finish is my proposal to 1.4.3 final.
That Algernon want to start with the engine control seems great, but I fear that as we incorporate things more difficult is it all in tune, so maybe we will slow down now :mrgreen: . Greetings
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Re: eurofighter typhoon

Postby Algernon » Wed Sep 29, 2010 9:32 am

I've also had a couple of busyish days - sorry I haven't yet got back to you by email, almursi. Are you saying that, following a little more work, we could actually produce a release for the aircraft? Because if so, I agree this would be the way to go.

From my perspective, both the jobs I want to tackle next - AFCS and DECMU (Eurofighter FADEC) - are big and scary!! So I would like to focus on tuning of the autopilot and perhaps working out the bugs in the cockpit (Upper Left Panel buttons bugs - very annoying) ready for this next release. Would that be an Alpha or Beta release? What I will also do is create a webpage on the FGUK website (fguk.co.nr) as a Eurofighter Typhoon hangar page, and I will also make the page template available for anyone who wishes to translate it into another language and host it elsewhere.
For this, I would really appreciate some screenshots of the aircraft from those of you with better graphics acceleration than me that I could use in my web design.

Creating a nasal engine startup sequence for the eurofighter (and other jets) is logical, not hackish. You have my full support, Algernon

Well that is great to know, thank you Detlef :) I have already started some experiments, my Eurofighter now has a gearbox thanks to some very simply Nasal code. My Nasal skills are at present very limited - apart from web design, my coding abilities never got much further than writing beginners BASIC on the Commodore 64 - but I'm anxious to learn and hopefully my basic code will become more sophisticated over time as more experienced developers make suggestions or offer advice.
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Re: eurofighter typhoon

Postby almursi » Wed Sep 29, 2010 3:36 pm

Algernon wrote:I've also had a couple of busyish days - sorry I haven't yet got back to you by email, almursi. Are you saying that, following a little more work, we could actually produce a release for the aircraft? Because if so, I agree this would be the way to go.


Hi, that's why I titled "Pre 1.4.3" for contributions to fine tune and strengthen the release on "Final". I have much to talk with you, just in the tuning of the sounds and the autopilot, but when I finish with the cockpit :). Regards.
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Re: eurofighter typhoon

Postby Algernon » Wed Sep 29, 2010 5:19 pm

Yep, we need to have that discussion - I have another sound project I've just been asked to work on, so I will be setting up my edit suite before the weekend. I will try and have the autopilots tuned up properly by then, so final job for me (for this release anyway) will be the sound. I have a lot of ideas to make it more realistic.

As for the release, I'm pretty excited: FGUK will happily host the file on our webspace (a bit more permanent that a file sharing website), and I've started work on this page for the FGUK hangar - anybody is welcome to use the page code if they want to use it to link to the file elsewhere, for example to translate it or something like that. Normal GPL conditions apply. :)
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Re: eurofighter typhoon

Postby DFaber » Wed Sep 29, 2010 6:11 pm

Hi almursi, algernon,

am I ok to put a unified 1.4.2 in Git? Then you can review if I did anything wrong. I like to adjust the blackout/redout settings a bit to adapt it to a Pilot wearing a G-suit.

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Re: eurofighter typhoon

Postby Algernon » Wed Sep 29, 2010 6:32 pm

DFaber wrote:am I ok to put a unified 1.4.2 in Git? Then you can review if I did anything wrong. I like to adjust the blackout/redout settings a bit to adapt it to a Pilot wearing a G-suit.

Oh thank goodness, I keep meaning to mention this and have thus far always forgotten, as my graphics acceleration is so poor I can't run the G-load graphics. It really needs to be starting to black/red out at 10g plus, and then hopefully the AFCS can be tuned so we get the highest performance, but limited before the pilot begins to feel the effects. I have heard in several places that the G-suit makes indefinite 9g possible without pooling.

I'm quite happy for the version to go into Git, do I need to submit anything?
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Re: eurofighter typhoon

Postby DFaber » Wed Sep 29, 2010 6:58 pm

Algernon wrote:I'm quite happy for the version to go into Git, do I need to submit anything?


Not if you don't want to ;-) I'll adjust the G-suite and wait another day until I put it in Git.

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