Conspicuous by Their Absence

Fixed Pitch Propellers

Glad it worked for you!

It is really cool to be able to tweak a single parameter to make a flight model do what you want, but sometimes it might be indicative of a more general problem that needs a bigger patch. If you switch to a complete CFS AIR file, you can get the engine torque effects, but there would be a LOT of things to fix.

I had to do some of the same things when I was building the Eindecker.
The biggest issue was trying to figure out how a fixed pitch propeller would behave and I basically cheated there:

I began with a P-51 as usual, and of course the Propeller Power Coefficient would have been WAY different, but it didn't matter because I left it as a constant speed prop until I got a reading of the prop angle at maximum speed which was then fed back into the AIR file.

There is an Albatros D.Va that needs a proper AIR file before I can finish it up. Problem is that I don't know how to build a biplane AIR file.

- Ivan.
 
Biplane wings in the .air file

Hi Ivan,

Things often get more complicated that one expects. It appears that FS98 .air files flying in CFS1 do so in "simplified mode". Also, the surface friction changes from asphalt to grass in CFS1 - planes that don´t move in Interlaken, do move in Velizy Villacoublay... Well, I´m not complaining - I´m thankful that FS98 .air files are at least compatible with CFS1 - even if not vice-versa!

As FS98 .air files have no entry for biplane wings, the 2 friends I had who wrote .air files for my "big planes" and "giant planes", did the Wing Section as follows:

Span: Span of the longer wing ONLY (usually the top).
Area: Sum total of both upper and lower wings.
Chord: Sum total of the average chord of both upper and lower wings.

The wing area parameter entry seems obvious, and the chord parameter being the sum of both chords would be obvious too, accounting for increased lift and drag of the two wings. The span not being duplicated would maintain the behaviour of the relatively short span of biplanes, as otherwise we´d have a huge glider, which would not do at all!

I hope this helps!

Speaking of "big" and "giant" planes...Somehow this sounds much more imposing in German - even the word "aeroplane", "Flugzeug" in German, means "flying thing", totally ridiculous in English! ...and a car would be a people´s powered wagon in German! Funny how languages transmit their own atmosphere.

I hope all followers of this thread and everyone else in SOH have a nice Christmas Dinner!

Cheers,
Aleatorylamp
 
Hello Aleatorylamp,

I believe that going full CFS AIR file versus modifying a FS98 version would be better.
If you don't have the same propeller records in FS98, then you probably can't simulate the very heavy gyroscopic effect of a rotary engine.

I don't know that the numbers you describe would not work, but I bet there are a lot more factors involved.
I have actually tried to read the NACA Report by Max Munk on the subject but the problem is that my math today is much worse than when I was in High School or College. This is pretty much the definitive information source, but unfortunately it is written mostly in mathematica formulae rather than readable English.

Things don't seem so obvious to me because with two wings, you run into the issue of stagger, gap, and doubled wing tip losses.
Are the angles of incidence the same? Are there interference issues between them? I am sure all of these would have an effect that isn't easy to simplify.

- Ivan.
 
.air file complications

Merry Xmas day to everyone!
Free time to do things is the best present!

Ivan, I´m afraid I´m out of my depth with the deeper details in FS98 .air files, let alone CFSD1 ones.
My understanding of aircraft, propellers and biplanes is rather simple. I wouldn´t know how to simulate the large gyroscopic effect - obviously the propeller inertia and propeller diameter parameters won´t be enough.
I know there is one parameter that refers to the engine torque pulling the plane right or left, but I don´t know which it is.

As regards biplanes, there are obvious limitations, and I doubt more complicated things can be simulated: Greater wing efficiency due to the combined effect between the wing-planes, and a possible staggerwing effect (top plane further aft) causing stall sooner are possible, I suppose, but only one angle of incidence entry is available (I don´t know if they can be different), so the possible effect of two different ones would have to be simulated using other parameters.

Probably the best solution is a work-around - i.e. going for the overall expected behaviour, playing around with the more complicated available parameters on the 3 axes, which unfortunately I´m not much help on.

Interference between wings and double wing-tip losses would perhaps create a greater altitude loss in turns, and a greater rudder effect on roll, probably not much difference in adverse yaw, but I don´t know. I´m very much out of my depth here, and not much help.

On top of this, we have the 2 different ways that AirEd and FDEdit refer to Angle of Incidence/Angle of Twist and Wing Efficiency/Angle of Incidence.

Such are the complications!

Anyway, for monoplanes, in my humble opinion, you have managed admirably on your P38 .air file and the Emil Messerschmidt!

Cheers,
Aleatorylamp
 
AEG G.IV almost ready

Hi again!

This would be the first of the "Grossflugzeug" - the big planes. I´ve been re-working the AEG G.IV rather heavily, and have had to take some decisions. Control surfaces were only 2d and needed body, and there were no crew or weapons. This required so many extra parts, that it was impossible to do with AEG G.IV-K: The anti-tank cannon in the cut-away lower nose, the biplane tail and the twin rudders were just too many parts, so I had to go for the AEG G.IV with its more conventional tail.

Even so, after eliminating the hollowed-out fuselage on the old model and getting the control surfaces into 3d, the shapes for guns and crew are rather square and simple, because I´ve completely run out of parts. There´s also nothing left for a rear ventral gun in a trapdoor, but perhaps it would be a good idea just to leave it in in the DP files - to surprise the enemy coming from below behind!

I still have to do some welding on hairline-gaps, but hopefully I´ll get it done for an upload after this weekend or so. Let´s see how it goes.

Cheers,
Aleatorylamp
 

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Hello Aleatorylamp,

Actually, increasing the propeller inertia is pretty much the way to simulate a rotary in my opinion.
I don't believe there actually is a parameter that controls the direction of propeller torque in CFS.
In CFS2 and later there certainly is such a parameter which I believe is in the Aircraft.cfg file.

I believe a Biplane is actually MUCH less aerodynamically efficient than a Monoplane.
Other than that and having read as much as I could of Max Munk's NACA Reports, I don't claim to know much more.
Eventually I will go back to work on the Albatros D.Va and need to understand enough to work on the AIR file.

You are certainly correct that it is possible to simulate a biplane from a performance standpoint, but I play in this arena mostly to learn, so it makes sense to do things as correctly as possible.

Regarding the "Big Flying Machine", how are you handling the gun positions?
If you are basing things on CFS stock aeroplanes, there is quite a lot that is wrong with those.
We have actually had lots of discussions about that over the years. Here is what *I* know about though there may be quite a lot more:

1. The Weight of Ammunition is simply wrong. On all the CFS stock DPs, the weight is only that of the projectile rather than the entire round.
2. The Hitting power of many of the guns is way off, but mostly this affects the cannon which would not typically be found in an aeroplane from the Great War.
3. The accuracy of gunners is entirely unrealistic. They are much deadlier than real gunners would be. A bomber intercept mission is very hard to survive. Bombers in the game hardly need fighter escorts.

In my opinion, the best solution is to restrict the range of the gun positions. It does not make sense for AI swivel gunners to have a greater effective range than fixed guns on a fighter with a reflector gunsight. Another way to slightly reduce their response time is to have the default direction different from the most likely direction of an attack
Perhaps others have, but I have not played with AI gunners enough to find a systematic way of configuring them but obviously I have a few ideas along these lines.

- Ivan.



- Ivan.
 
"Big Flying Machine"

Hello!
I have just uploaded an AEG G.IV "Big Flying Machine" night bomber:

http://www.sim-outhouse.com/sohforums/local_links.php?action=jump&catid=19&id=19284

Re-work went very well indeed thanks to what I´ve learnt here, i.e. the clever gluing sequences (pots and pots of glue!), with which bleedthrough is only very scarce, and very short! Also, by ratioinalizing structures and things, I was even able to get the parts for the "belly shooter". Be warned, however: The 3 crew members and the guns have rather simple square shapes. Parts count at 149.8% and 30 components and 29 structures wouldn´t allow much else.

Ivan: CFS1, and FS98 to a greater degree, unfortunately will in some cases not leave much alternative but to find work-arounds for some techical details.

Grossflugzeug Dp files:
Thanks for the information! I´ll try to adjust some of the things on future models. For the moment, I´m taking some Dp files that were written some years ago by A.F. Scrubb for the Gotha Grossflugzeug series, and have adjusted the firing points to fit the positions as per the models. For the AEG, and future uploads of Gotha, Friedrichshafen and Staaken models they should be fine. I´m afraid I haven´t delved into any more DP details, as the numbers didn´t make much sense to me as yet.

Well, let´s see what happens...
Now for another big oldie, a Gotha I think, this time!
Cheers,
Aleatorylamp
 
Technical Details

Every desktop flight simulator has some kind of compromise or approximation.
It is no surprise that CFS (and FS98 to a much greater extent) have their issues, especially considering their age.
I don't claim to understand them all because my own knowledge has even greater holes.

Our choice as always is either to give up or figure out some work-arounds.

Long ago, I was told that a Spin is impossible in CFS. I don't know if that is completely true or why but I can also tell you that I have a couple aeroplanes that do a pretty fair imitation of a Spin.

Up until now, I had never seen a flight model for a P-38 in CFS that did not exhibit a great deal of asymmetrical engine torque which the contra rotating props were designed to address. I don't know that my own solution doesn't break something else in the simulator but it does a pretty fair job of pretending to have negligible engine torque effects.

Son needs the computer and I don't have one of my own at the moment....
Good Night.
- Ivan.
 
.air file help for old engines

Hello, hello!
I was wondering if perhaps Hubbabubba would like to help me with the CFS1 P51D .air file that I´m adapting for the Zeppelin Staaken R-6 giant biplane of the Great War which I´m preparing for upload. Engines won´t start unless throttles are open and when set to idle for landing approach, they stop! I´ve entered the new engine parameters, leaving the restly P51D ones unchanged. Perhaps there could be a couple of suggestions that could help.
Specs are as follows:
Type of engine : Mercedes D.VIa high-compression airship engine
Number of engines Engines: 4
Number of cylinders : 6
cylinder displacement : 220.6 cu in. (huge cylinders)
Compression ratio: : 4.82 (high compression does not allow full power at sea-level)
Max. rated engine power : 267 hp at 4265 ft.
Max. rated RPM : 1450
Max. governed RPM : 2400 (should be 1450 but not effective in FS)
Min. governed RPM : 1400 (should be 400 but not effective in FS)
Turbocharger : yes (to mimic throttle-gated HC Zeppelin airship engine)
Critical altitude : 4300 ft
Manifold pressure max. : 30 (or leaving it at 61 won´t help)
Emergency Boost : 0
Propeller diameter : 11.16 ft (2 blades)
Propeller type : fixed pitch 25


Perhaps it would be convenient to e-mail the plane?

Many thanks in advance for the attention given, and any possible suggestions!

Cheers,
Aleatorylamp
 
custom panel problem

Hello, hello again!
I wonder if anyone has the solution to a panel problem other than simply using the default CFS1 ones.
Although I´ve managed to eliminate the blacked out sections which should be transparent, all my FS98 custom panels for the old biplanes are playing up in CFS1, even using only default gauges: If your plane crashes and want to fly again, CFS1 hangs and has to be re-started again.
Cheers,
Aleatorylamp
 
hello aleatory....(long name)
have you ever been to Grumpy's Lair?
this link will send you to his intro page,
scroll down to enter the Lair,
find and click on the cfs panel clinic.
if you can't find the information you need,
let me know and we'll go from there.

http://simviation.com//lair/intro.htm
 
panel size the culprit?

smilo said:
hello aleatory....(long name)
have you ever been to Grumpy's Lair?


Hi Smilo,


Thanks very much for your fast answer!
Yes, Grumpy´s lair shows a couple of interesting panel issue solutions, but not about panels being to blame for CFS1 hanging when you try to fly again after the your plane has crashed. It´s not exactly "hanging" - It´s actually the Microsoft Sign appearing and telling you that the CFS1 module has encountered a problem and has to shut down, and asking you if you want to notify Microsoft about it (of course I don´t!).


But: The X-Y panel size maximum parameter at the end of the panel.cfg file mentioned in Grumpy´s Lair gave me an idea that I´ve just tried out, and although the parameter in my .cfg file is correct, the actual bitmap size appears to be the problem: I copied my panel bitmap onto both of the P51D panel bitmaps - the 1024 one and the 640 one - (re-sizing automatically), and also the panel.cfg lines about the instruments I wanted, and now it works perfectly!...although the colours are somewhat off, but I´ll fix that.


So, I deduce from this, that the problem must be the "unorthodox" 1060x623 size of my panel bitmaps!


I will have to upload new panels for at four of the planes I´ve uploaded recently - those also create problems.

Edited to update this post: I´ve just been correcting the colours on the panel bitmaps and the problem with CFS1 shutting down has started again. I wonder what´s going on... How can changing colours on a CFS1 panel bitmap do this?


Thanks again for your answer!
Cheers,
Aleatorylamp
Click to expand...
 
Last edited:
engine torque

Hi Ivan,

I remember someone telling me to counteract the torque by "moving" the engine a bit to the opposite side.
That actually sounded more like something one had to do on a RC model airplane - but I wonder how one could emmulate the Sopwith Camel: Because of the tremendous gyroscopic effect of the heavy rotary engine, it had a very sharp right turn, and a much slower left one, so much in fact, that pilots often preferred to do a 270 degree violent turn to the right in order to go left!! That really outwitted the enemy!

Cheers,
Aleatorylamp
 
it's too easy for me to say
the bitmap was the problem,
especially, after the fact.
but, what else could it have been?

at any rate, i'm pleased
the problem has been resolved.
 
Engine Torque

Hello Aleatorylamp,

What started me on the idea of moving the Port Side engine on the P-38 WAY out was the excursion I took with the Blohm & Voss BV 141B.
It was designed as a single engine aeroplane with the engine offset very far to port to eliminate torque effects. In working on the flight model, I found that they had probably over done it a bit because the aeroplane would pull to Starboard. The effect also changed with varying airspeed which is why I did not think it would work as well as it did on the Lightning.

This method certainly has other issues because there are many factors that contribute to the asymmetrical effect of a rotating propeller.
P-Factor as an example is certainly not eliminated though in this case, it isn't severe because of the very slight ground angle of the Lightning.

There are many apocryphal stories about various aeroplanes including the Camel. You should take my Eindecker out for a spin and let me know if it has some of the torque and gyroscopic effects of a rotary. I think it does and that was a very small rotary engine.

There are many little goofy things people have done to counteract propeller torque. Most of them can't be done with a CFS flight model:
The Hellcat and others have a thrust line inclined downward.
The Bloch radial engine fighters have a thrust line aimed off to one side.
The Macchi fighters have one wing longer than the other.
The Lightning with its directional propeller rotation is something we are already discussing.
How do we handle a single contra-rotating propeller as found on a late model Spitfire?
How do we handle aircraft with propellers rotating the opposite direction as found on the Hawker, Yakovlev, and other fighters?

- Ivan.
 
panel still playing up

Hi Smilo,

I´m afraid I sang victory too soon, it must be something else, for now, even just aliasing a P51d or a Sopwith Camel panel, it makes CFS1 shut down when trying to fly again after a crash. The funny thing is that occasionally, it doesn´t happen!

This brings me to the conclusion that it must be my computer or the Windows XP operating system which is most probably too new for CFS1.

But at least, the planes can fly, which is already a good thing. I do have an old Windows 98 Pentium III computer I could use, but I was trying to avoid having to do that.

Well anyway, thanks for bearing with me!
Cheers,
Aleatorylamp
 
Hi Ivan,
Human ingenuity has almost no limits - and is sometimes very funny, how things are done for a certain purpose. Very intriguing, the list of how different manufacturers counteracted torque!
It looks like one will have to strain one´s brain to solve certain .air file issues...
I have just downloaded your Eindecker to try out soon, and I hope to comment on it!
Cheers,
Aleatorylamp
 
i kinda doubt that xp is the problem.
i've been using it for years.

if you would, please, zip up the current aircraft
you're having a problem with...as it is.
email it to me and i'll have a look.
no guarantees, but who knows?
an extra set of eyes might help.

check you PM for my email address
 
idling the old aero-engines in the .air file

Hi all!

Interesting... I found the solution to the start-up/idle problem in the .air file which large, old, slow, low-power aero-engines seem to have (they needed 60% power for start-up and stopped below 15% power):

There is a graph table called "Engine Throttle Effectivity Table" in AirEd, with an Info reference saying "set throttle idle stop and max mp wrt intake". This table is a 2 point straight line graph going from X=0 to X=1 with Y settings at 0.2 and 0.98. Raising the second Y parameter to 1.2, I managed to get the engines to start up without opening the throttle and now they don´t conk out when idling on the approach.

Cheers,
Aleatorylamp
 
smilo said:
it's too easy for me to say
the bitmap was the problem,
especially, after the fact.
but, what else could it have been?

at any rate, i'm pleased
the problem has been resolved.
Click to expand...

i can't express how much it pleases me
when an arrogant know it all
is put in their place.
especially, when the arrogant know it all is myself!

as i turns out,
the problem is caused by something in the DP.
(at least, it appears to be)
after deleting the DP and CDP files,
the issue ceased.
go figure...shows what i know>>>:icon_redface:
 
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