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RC3 issues with Alpha masking and JSBsim FDMs

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RC3 issues with Alpha masking and JSBsim FDMs

Postby LesterBoffo » Sun Jul 29, 2012 1:18 pm

Well I will admit that I was wrong about some of my comments about Rembrandt, at least in version 2.8.3 RC3, it actually works pretty fairly on my machine, even squeaking in an occasional 22 fps at KSFO in MP with a fair amount of activity ongoing. But, I am having serious issues, and I'm wondering if these are RC3 bugs or just my not setting Rembrandt up correctly.

The glass effect fix from the Wiki to convert 2.6 aircraft windows to 2.8 seems to work well, but the alpha channels on all propeller prop disk's have lost all transparency, making them black discs, and unless I missed a crucial instruction, (and I've searched this forum and a lot of associated Rembrandt topics in other forum catagories..) this is enough for me to revert back to 2.6.0.

The other big issue is that for some odd reason, JSBsim IC piston engined aircraft, and especially old time, low compression ratio engines are nearly impossible to start. At least not without some rather strenuous sim magiking like ctr+u up to '8000, point the nose down vertically, and hold the starter on for a half minute while cycling the throttle, and maybe the engine will catch. And for most JSB sim piston engines, they seem to have suffered an noticeable reduction in power, and an inability to hold an idle.

I have no idea what change in the code were implemented that deals with JSBsim FDM's but it's a big step retrograde.
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Re: RC3 issues with Alpha masking and JSBsim FDMs

Postby LesterBoffo » Sun Jul 29, 2012 3:13 pm

here's a couple examples of prop discs that are working in 2.80.3 with Rembrandt..

Image

Image

they're a bit less transparent than these models are in 2.6, but better than the completely black disc present in my Blenheim in 2.8.0.3 with Rembrandt. I have no idea why these are working vs. the ones that aren't, I've checked the alpha channels on ones that do work and they appear to be the same as the ones that don't.
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Re: RC3 issues with Alpha masking and JSBsim FDMs

Postby fredb » Sun Jul 29, 2012 3:52 pm

Is there a problem with these two screenshots ?
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Re: RC3 issues with Alpha masking and JSBsim FDMs

Postby LesterBoffo » Sun Jul 29, 2012 5:18 pm

Well I should have posted the Boeing 347 or the Beech 1900D as images, but I had just discovered my two newest models props were working in Rembrandt, seems we may have sussed this to a good result for the prop transparency at least, the JSB sim piston engine issue still exists with 2.8 RC3 for four of my aircraft though.
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Re: RC3 issues with Alpha masking and JSBsim FDMs

Postby jonsberndt » Tue Jul 31, 2012 4:30 am

LesterBoffo wrote in Sun Jul 29, 2012 1:18 pm:Well I will admit that I was wrong about some of my comments about Rembrandt, at least in version 2.8.3 RC3, it actually works pretty fairly on my machine, even squeaking in an occasional 22 fps at KSFO in MP with a fair amount of activity ongoing. But, I am having serious issues, and I'm wondering if these are RC3 bugs or just my not setting Rembrandt up correctly.

The glass effect fix from the Wiki to convert 2.6 aircraft windows to 2.8 seems to work well, but the alpha channels on all propeller prop disk's have lost all transparency, making them black discs, and unless I missed a crucial instruction, (and I've searched this forum and a lot of associated Rembrandt topics in other forum catagories..) this is enough for me to revert back to 2.6.0.

The other big issue is that for some odd reason, JSBsim IC piston engined aircraft, and especially old time, low compression ratio engines are nearly impossible to start. At least not without some rather strenuous sim magiking like ctr+u up to '8000, point the nose down vertically, and hold the starter on for a half minute while cycling the throttle, and maybe the engine will catch. And for most JSB sim piston engines, they seem to have suffered an noticeable reduction in power, and an inability to hold an idle.

I have no idea what change in the code were implemented that deals with JSBsim FDM's but it's a big step retrograde.


This would be a good one to post to the JSBSIm developer list. Or, you might search the list. i think this might have been addressed there.

Jon
Jon S. Berndt
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JSBSim Project
http://www.JSBSim.org
http://www.facebook.com/jsbsim
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Re: RC3 issues with Alpha masking and JSBsim FDMs

Postby LesterBoffo » Wed Aug 08, 2012 6:12 pm

(JSBSim engine problems cont..) I've discovered, messing about with the engine .xml's in my 4 antique aircraft, that don't idle and start well, is that I had the low rpm level set too high. Especially for the Sopwith Strutter with it's 990 cu inch displacement Clerget, which was not being spun up fast enough to start and would only reach about 300 rpm. I had the low rpm set threshold at 600, which considering that rotaries of this period didn't have much in the way of throttling. But historically you did have a fuel mixture and air-volume control levers that could be used to "idle" the LeRhone, Oberusal UIII, Bentley, and Clerget engines down to about roughly 500 rpm, so I lowered the RPM threshold to 250 and now the Clerget starts, and (..unrealistically..) idles at about 180~210 rpm. So it's a step in the right direction and it's working better.

I'll put in a mention of the problem in the JSBSIm developer list and see what comes of it Jon, thanks.
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Re: RC3 issues with Alpha masking and JSBsim FDMs

Postby jentron » Sun Aug 19, 2012 9:51 pm

LesterBoffo wrote in Wed Aug 08, 2012 6:12 pm:(JSBSim engine problems cont..) I've discovered, messing about with the engine .xml's in my 4 antique aircraft, that don't idle and start well, is that I had the low rpm level set too high. Especially for the Sopwith Strutter with it's 990 cu inch displacement Clerget, which was not being spun up fast enough to start and would only reach about 300 rpm. I had the low rpm set threshold at 600, which considering that rotaries of this period didn't have much in the way of throttling. But historically you did have a fuel mixture and air-volume control levers that could be used to "idle" the LeRhone, Oberusal UIII, Bentley, and Clerget engines down to about roughly 500 rpm, so I lowered the RPM threshold to 250 and now the Clerget starts, and (..unrealistically..) idles at about 180~210 rpm. So it's a step in the right direction and it's working better.

I'll put in a mention of the problem in the JSBSIm developer list and see what comes of it Jon, thanks.


I never saw anything on the developer's list, sorry.

In 2.8 there is a new, much improved starter motor code. This starter motor code more closely mimics a real electric engine and so spins up more slowly than the old starter motor code. I'll quote the wiki page for the interesting new properties:
<!-- Added in FlightGear 2.8 -->
<starter-torque> {number} </starter-torque>
<starter-rpm> {number} </starter-rpm>

starter-torque (fgfs 2.8) A value specifying the zero RPM torque in lb*ft the starter motor provides. Current default value is 40% of the maximum horsepower value.
starter-rpm (fgfs 2.8) A value specifying the maximum RPM the unloaded starter motor can achieve. Loads placed on the engine by the propeller and throttle will further limit RPM achieved in practice.


You can make your starter motor more powerful by putting a larger number in the starter-torque tag. There is also a property I didn't mention on the wiki page called /fdm/jsbsim/propulsion/engine/starter-norm. It is set to 1 by default, and is a multiplier to starter-torque, so you can set it to a larger value to figure how much torque you need to start. You can also control it from e.g. nasal to add some electrical systems detail.

Ron

P.S., I tried to get the new code to default to a large enough value of starter torque to start all the current engines. Can you point me at the four airplanes having trouble and/or tell me if raising the starter-torque value helps and what value you used as a percent of maxhp?
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Re: RC3 issues with Alpha masking and JSBsim FDMs

Postby jentron » Sun Aug 19, 2012 9:53 pm

Also, the peak horsepower of the starter is achieved at 1/2 starter-rpm
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