I'm thinking of editing/overhauling the air file for the Hawker and fix some issues I find with the way thrust and fuel use is modelled.

 

My aim will be to:

 

Fix spool up time to be longer, especially at engine start.

Fix thrust vs altitude and throttle and speed to better match book performance.

Fix fuel use at lower throttle settings.

 

I've spent a bit of time learning how it all works but haven't tried tweaking jets before so this might be an iterative and learning process for me too.

 

Would anyone be keen to test it out as we go?

Don't think the spool up should be longer, these are not huge engines.

Don't think the spool up should be longer, these are not huge engines.

Really? I find when the HP cocks are opened the N1 shoots up, as do ITT. If it's realistic I'll leave it but it seems very quick to light up?

Spikes are one thing... but timing is another.  Don't confuse the two.

 

I would expect this aircraft's engines to light off in about the same time as any other light business jet.  The Cessna Mustang's engines take less than 25 seconds from start to idle.

...  I'm interested in someone fixing the autopilot logic,,,   that would be neat,  

 

From not knowing anything about XML/SPB I've picked up a little bit by trying to fix this although not really getting anywhere,

 

They seem to have added an 'upate' within the script which seems to make it harder to work out what's going on.

 

The other main obstacle is working out what all the listed commands mean and what certain letter suffixes do.

 

e.g.

 

(>L:ALT_ARM_SEL_ON_KNOB, number)                               -  = get value of number selected ?

0 (>L:ALT_VS_SEL_ON)                                                         =get and check vert speed is not on ?  What's L mean (look)?

(>K:AP_ALT_HOLD_ON)                                                         =   what's the  K  for ?   kill the function ?

.(>L:ALT_ARM_SEL_ON)                                                        

(>L:ALT_ARM_SEL_ON_KNOB, number)

0 (>K:AP_ALT_VAR_SET_ENGLISH)                                     =diff between selected alt and actual alt ? VAR - variance

0 (>L:CUSTOM_AP_ALT_VAR_SET_ENGLISH, feet)               =diff between 

 

these are a few examples.

 

The priority for me at the moment is to stop the plane climbing as soon as an altitute is put in on the 'alt sel' rotary. It even does this with  'ALT HOLD' on.

 

capturing altitudes, 

 

plane bouncing along at the stall and not getting out of it until AP off/on, (changes to and stays on speed hold (usually at a very low speed) mode even if any other mode selected.

etc etc etc...

 

aero

Aerostar, I've spent a lot of time fixing xml coding for the Carenado PC12 and stuff like autopilot logic is an entirely different beast compared to the flight behaviour.

 

If you want to discuss xml coding I would recommend we start a separate thread to this one as I'd prefer to keep this on a discussion of whether the plane flies correctly and what we can do to address those shortcomings.

Hey autogyro ,  

 

that sounds like a real good idea,,,  

 

we could  ' clarify '  any errors that  -might-  exist and maybe find a solution and others may get involved too and help out.

As I've said I haven't done anything like this before and I'm flying blind and guessing so , unfortunately, I won't be able to supply much useful input although I can try.

 

... great if you would start a new thread on this,,,

 

aero

I'll put something up tonight my time

Great initiative

I'm thinking of editing/overhauling the air file for the Hawker and fix some issues I find with the way thrust and fuel use is modelled.

 

My aim will be to:

 

Fix spool up time to be longer, especially at engine start.

Fix thrust vs altitude and throttle and speed to better match book performance.

Fix fuel use at lower throttle settings.

 

I've spent a bit of time learning how it all works but haven't tried tweaking jets before so this might be an iterative and learning process for me too.

 

Would anyone be keen to test it out as we go?

 

I too think the spool time is ok but the fuel flow is way off.... At cruise (compared to book) at ISA+10 is was supposed to be around 1750lbs/hr - I was at ISA +12 and was getting 1540ish lbs/hr.... I have been meaning to test this more but maybe this can be solved by increasing the fuel scalar?

So far so good. Just need to get fuel flow right and I think it's somewhat of an improvement over default.

Sounds great autogyro! Your work is highly regarded, especially for this 'un-finished' aircraft ^_^ . I appreciate it mate.

 

MD

Ok, anybody want to test it out and provide feedback, please PM me.

I can't seem to get a good result for fuel flow.

 

Having read some more it seems you can only achieve a compromise between cruise fuel use and long range cruise fuel use as thrust specific fuel consumption is a static value. I've currently set it between long range and cruise, but at least with correct (or better than default anyway) thrust in most flight regimes.

 

So at max cruise at FL370 it uses 1750 lbs/hr instead of 1820 and at long range cruise it uses 1500 lbs/hr instead of 1180.

 

The only way I believe I can correct this is to adjust the net thrust lower at long range cruise speeds but that means flight performance is negatively affected.

Okay first version released for testing. See what you guys think.