Conspicuous by Their Absence

[Ivan]

One thing worth tuning:

If I were you, I would seriously consider tuning the Maximum level speed at critical altitude. You will most likely find that several extra knots will increase your power and rpm numbers and put them in your target range.
Remember that propeller drag by low advance ratios is how we are limiting low end power.

- Ivan.

[aleatorylamp]

Hi Ivan,
Dont´worry, I´m OK! Even with the Beckwith test-panel... ha ha!

As you say, the first thing I did was try to get maximum speed at critical altitude right - that was the 70 Kt with 267 Hp at 4300 ft. Originally we had 73, but that inexact, as I recently found better information. 73 Knots was for the Giant with Maybach engines, and that had 245 Hp at 8200 ft critical altitude.

I don´t know technical German, but Dienst Gipfel Höhe sure sounds correct! In my ignorance, the 16 fpm was the result of the division of the last climbing leg distance by the time upto Dienst Gipfel Höhe:

The Mercedes-powered Giant had the following climbing specs:
Climb: 1000 m. (3281 ft.) in 11 min.
2000 m. (6562 ft.) in 27 min.
3000 m. (9843 ft.) in 55 min.
Ceiling,3800 m. (12,467 ft.) in 150 min.

With my experiments, one of my motivations is "to see if it works". That´s why I built a space-ship for FS98. It flies so high that it crashes FS98 at about 120,000 ft! There´s NOthing like seeing if something works! Pity the spaceship has too much bleedthrough for CFS1... otherwise I´d upload it!

Anyway, you wouldn´t believe it: I just now actually had the Giant (I know now it´s absurd) where it won´t climb at all above exactly 12470 ft, and just below that, it only does 1 or 2 fpm.... From what you have just said, this is complete idiocy! Anyway, it is not the only thing that´s idiotic, because all the restly rates of climb are on the blink! Mostly less than half, so I promptly threw out the .air file.

I have a student who is a painter - pictures, not houses - and he says that one difficulty is knowing when to finish a painting, and not to spoil it by over-finishing it!

So OK then, where I was before (I have secured the .air file with 3 backups), everything tied in more or less fine. I also had the general feeling it was good, even though the climbing time was rather on the short side for the last leg. What I like during the climb is that you feel the engine accellerating as it reaches critical altitude. It´s really amazing how the .air file manages to emmulate the throttle-gated engines by means of the turbocharger!

I understand your argumentation and your thoughts on this, and quite agree with you, even though I only use the autopilot for the wing-leveller and do climb testing with elevator trim. I do slew up and down sometimes too for short specific tests.

Well, I´m just finishing the panel before uploading the plane (only default gauges, though). There´s a photo I might use to make some changes there. The cockpit looked like an airship cockpit, and some of the instruments were in the engine nacelles with the mechanics, so I may make some combinations.

Right now I have a different, perhaps much more serious problem: My original CFS1 CD is a bit deteriorated, and the working copies for every-day, all-day use, in the computer all the time, only last a couple of months before deteriorating, and now the DVD-ROM is starting to have problems, even though it´s relatively new. I hope the whole thing doesn´t expire, because I´ll have to hunt around for another CFS1 CD - after I get a new DVD-ROM, of course.

Well, let´s see what happens!
Cheers,
Aleatorylamp

[aleatorylamp]

Hi Ivan,
I just found a reference to the cruising speed, so I was wrong. You were right, there was one:

Cruise:
When above anticipated anti aircraft engagement envelope
- REDUCE THROTTLE until altimeter is steady
- Trim
- Typical cruise 100 Kph IAS (54 kt)

That´s like a pleasant country-ride in the car!!

The other 5% slower than maximum info was a second maximum continuous setting that existed only to facilitate formation flight on the way to destination.

Then, I found the info on max. Cruise:
Maximum Cruise: 130 km/h (70 kt) for Mercedes Engines, 135 Kph (73 Kt) for Maybach engines
FULL THROTTLE continuous cruise is authorised subject to;
- ALTITUDE > 1300 meters (4265ft) with Mercedes engines or > 2500 metres (8200 ft) with Maybach

Also:
- AEROBATICS are PROHIBITED (ha ha!)

These antique aircraft certainly had peculiar operating techniques.

Cheers,
Aleatorylamp

[Ivan]

Hello Aleatorylamp,

There is nothing idiotic about a zero Rate of Climb at 12,500 feet.
That just means 12,500 feet is your "Absolute" Ceiling instead of Service Ceiling.

The original tuning I did for the 14 foot propeller was so that it would achieve 1450 RPM at 4350 feet with 265 HP
AT 84 MPH. Perhaps it could do this with a touch less power or a touch less speed, but probably not much less.
If you change the maximum speed to 70 Knots (80.5 MPH), you MAY have to do some tuning on the Power Coefficient Table (Record 512) to make things work out. It won't be much of a change I expect, and perhaps the original values might work.

From a conceptual standpoint, it isn't the Supercharger that is letting you achieve a power difference between Sea Level and 4300 feet.
I believe it is mostly the lugging propeller with a little assistance from a "Supercharger" so that the engine can maintain sea level ambient pressure up to 4300 feet. The funny thing is that even if you specify NO BOOST on the supercharger, it will still raise power up to a certain altitude.which is not the case if it has no supercharger!

You are always free to upload what you want. I certainly can't argue with you about the aeroplane because I really know very little about it. I have only browsed a Wikipedia article.

- Ivan.

[aleatorylamp]

Hi Ivan,

I meant that it was the almost zero ft climb rate I set up for the service ceiling that was itiotic, because I had realized from your post that the concept was different - I didn´t know that it meant that a minimum climbing power was left.

Yes, and not to worry, I understand that a) the "supercharger" in the .air file, sets in at critical altitude (not below) and supplies extra power from there up - and b) the slow lower altitude power is due to the AR´s on the propeller tables.

Oops! I thought that the propeller could be the same virtual 14 ft one for both Mercedes and Maybach engines.
I just increased the Zero Lift Drag to get 70 instead of 73 Kt!

So OK, thanks, I should now adjust the Propeller thrust table a little to make the propellers slightly less effective and then reduce the Zero Lift Drag to get the same 70 Knots that I´m getting now.
The present AR 0.2=0.10000 Thrust could perhaps go down to 0.09500, and that would also help to reduce the climb rate above critical altitude, I suppose.

In fact, I was thinking supplying a Maybach powered model too, by texturing the plane differently and getting some parts free for a central tail fin - same propeller, 245 Hp, 1400 RPM at 8200 rated altitude, 73 Kt max. speed. - but apparently from what you say it´s not so easy.

I was also trying to use the same engine with a 10 ft Propeller for a twin-engined bomber, but it´s obviously not so easy either. For the moment I´ll stick to getting the Mercedes one better.

Another strange thing is that apart from Turbo/Supercharger parameter=1,
Supercharger low-altitude boost also has to =1.
With a zero there, the engine is too weak below critical altitude!

Well anyway, I´ll see how it goes.
Thanks, and Cheers,
Aleatorylamp

[Ivan]

Hello Aleatorylamp,

I am sure you probably understand but your statement didn't seem quite right.
A supercharger allows an engine to maintain maximum boost pressure up to its critical altitude.
In the Giant's case, it allowed SEA LEVEL manifold pressure 29.92 (?) inches Mercury to be maintained up to 4300 feet.
Above critical altitude, the supercharger can not compress air enough to maintain maximum boost and power falls off.

Because 4300 feet was such a low altitude for maximum power, we used propeller drag and RPM limitations to reduce power on the Giant.
If you have a higher altitude for maximum power, perhaps the supercharger alone can do it.
The problem though is that you may end up with an even stranger power to altitude curve than the Giant has.

This one is complicated enough that I can't visualize what will happen without actually experimenting, but you already know enough to do the experimenting at this point.

- Ivan.

[aleatorylamp]

Hi, Ivan,
No no, excellent! I had indeed wrongly undestood exactly the opposite: that the supercharger was doing the work higher up. OK, so critical and rated altitude, although they in this case happen at the same altitude, mean different things. I now understand a supercharger boosts upto critical altitude, and then power falls off as for a normal engine, contrary to "overcompressed" engines, which were limited upto rated altitude, only being allowed to develop full power there, power then falling off normally too.
So , if I have understood correctly, what we have done in the .air file is to limit the supercharged engine power with the large, slow propeller upto rated/critical altitude. The slow increase in RPM then allowed adjustments to get the power correct at critical/rated altitude. The higher RPM range then also allowed power adjustments after that, of course, only until RPM went down again and overlapped with the low-level performance limitation.

At the moment I´m correcting the AR 0.2 setting in the Propeller Thrust Table 512, which was at 0.0100000, and I said I´d try and lower it to 0.009500. After compensating Zero lift Drag to get 70 Kt at max. power at rated/critical altitude, the results for the desired power reduction higher up seem to be more correct by increasing it to 0.011000, rather than by lowering it to 0.00950. I want to limit the propeller a bit more, but the effect is obtained by increasing, not by decreasing the AR value there, right?

The possible different Maybach engine performance experiments will be conditioned to whether I can produce a model with the central tail fin, for which I have insufficient resources. Possible simplifications are 2D gunner silhouettes, 2D engine radiators, eliminating the central engine-nacelle component and doing the mechanics´cockpits it by changing the shape of the structures for the forward and rear engine-nacelle halves, but it all seems like a botch, and goes in detriment of the model itself. It is already unfortunate enough having had to do away with the transparent cockpit, and I don´t want to spoil it any further, so I´m not sure if I´ll do it yet.

OK, thanks again Ivan, and I hope everyone has a nice weekend!
Chairs,
Aleatorylamp

[Ivan]

Hello Aleatorylamp,

I believe your latest comments about superchargers is pretty much correct.
Ratings however are an interesting thing and I am not sure they usually provide useful information for a CFS Air File.
The reason is this:
We may have a particular radial engine soon to be adopted by the US Army Air Corps.
It is rated for 1000 HP at 2550 RPM at 10,000 feet
So what does this number really mean? Sometimes not all that much as far as we are concerned.
The maximum continuous output of this engine is 875 HP at 9,000 feet at 2400 RPM.
The Take-Off power is 980 HP at 2550 RPM that may be used for 1 minute.
The War Emergency Power for this engine may be 1100 HP at 2600 RPM at 10,500 feet and that may be used for 5 minutes.
The "Critical Altitude" for this engine is 10,500 feet.
The maximum speed for the brand new pursuit it is installed in is 320 MPH at 11,000 feet, so the "Critical Altitude" for the aircraft is 11,000 feet.....
I believe this is a fairly plausible combination and in this case, the "Rating" is a reasonable comparison between this and other engines under "Military Power" (non WEP) but may not mean all that
much to us in trying to simulate it in the game.


*****

If we are discuss Advance Ratios much more, we might as well use proper terminology:
Typically the symbol used to represent Advance Ratio in formulas and equations for Aeronautical purposes is "J".

It represents the relationship between actual forward motion of the propeller in relation to its rotational speed multiplied by its diameter.

It is not affected by ANYTHING other than RPM, Propeller Diameter, and Forward motion.
So how does this value change in the simulator (and in real life)?
If you go faster, J increases.
If you turn the propeller SLOWER, J increases.

Now Please refer to post #980 again:
For the 14 foot (How did the Germans get a metric sized 14 foot propeller anyway?)
J=0.0 -- 0 MPH
J=0.2 -- 46 MPH
J=0.4 -- 92 MPH

SO.... If you are messing with the power coefficient at J=0.2, you are probably affecting your climb RPM by a bit but not affecting your RPM at maximum speed by much.
70 Knots is about 81 MPH which is a bit closer to J=0.4.
Besides, Messing with Record 512 just affects the speed versus RPM balance. It doesn't directly affect your engine power or thrust.

- Ivan.

[aleatorylamp]

Hi Ivan,
I had just prepared a post to say that different test results for changing values for J=0.2 both slightly up and slightly down hadn´t been successful, and that the results previous to these last trials had been much better, and wanted to leave it at that. In fact, they pretty much messed up the power/speed/climbing rate balance I had acheived earlier, and interfered with the power build-up before rated altitude, either exaggerating or almost eliminating it.
I had also wondered in which particular area of my last performance result table you still had misgivings.

Thank you for the explanations! I will try and digest the technical details.
Here is the information as to the large german Propellers, just in case your question was not rhetoric!
Propeller centres, 8.0 m. (26 ft. 3 in.)
Tractor propellers diameter, 4.26 m. (14 ft.)
Pusher propeller diameter, 4.3 m. (14 ft. 1 in.)

So, OK, then, I´ll mess around with J=0.4 in the Prop Thrust Table! Thanks for pointing it out more exactly! Just to confirm, what we are now trying to achieve is to correct the J=0.4 value for it to more exactly fit the speed reduction from 73 Kt to 70Kt. I suppose that one of the effects will be that the climb rate higher up will go down, which is the area where performance is still a bit out.

OK, let´s see what I can come up with!
Cheers,
Aleatorylamp

[Ivan]

Hello Aleatorylamp,

Actually, I would expect the climb rate to go UP instead of down.
Record 512 is actually a "Propeller Power Coefficient" Table.
It has absolutely nothing to do with the amount of Thrust being generated.

Earlier, the Propeller achieved full 1450 RPM just a bit before 73 knots or 84 MPH at 4350 feet.
That means that it may not achieve 1450 RPM at the new maximum speed of 81 MPH.
In order to correct this, you will need to drop the Power Coefficient slightly but the side effect is that the propeller will spint up a bit faster at lower airspeeds as well.
Therefore at climb airspeeds, the power coefficient will now be lower and provide less resistance and the resulting RPM will be higher.

The reason I had even a few more misgivings than I stated in the last few messages is because although I can see that one CAN tune multiple variables at once and achieve results, I have always thought it was too complicated (at least for me) to do this reliably.

- Ivan.

[aleatorylamp]

Hi Ivan,

OK, I decreased the J=0.4 value first from .008600 to .008500, and then, as nothing happened, to .007000,
and as you said, climb rate and RPM go up for climbs below and after rated altitude.

However, for some obscure reason, RPM for level flight at rated altitude stays where it was: 1436 RPM!
Also, as you said, Hp is not really influenced and depends on the setting in the Torque graph, so we needn´t worry about that.

The problem now is that the increased climb rate and RPM causes the power surge, that normally sets in a couple of hundred feet below rated altitude, to start far sooner and become too strong, so climb rate shoots up far too much. Lowering the nose for level flight, it settles down then.

I have the feeling that when you mentioned that on second thoughts, perhaps the 73 to 70 Kt drop would not require any adjustment, the present situation would tie in with that.

Well, I hope this makes some sense!
Cheers,
Aleatorylamp

[Ivan]

Hello Aleatorylamp,

I wish I had some words of advice and wisdom, but the problem right now is that I no longer have a feeling for where your flight model is as compared to where it started.

It is very much like playing a long game of blindfold chess. Each move isn't hard. Early on, the moves are obvious because the position is easy to remember, but as the game gets longer, the current position gets much harder to remember and the problem becomes one of figuring out the position first before deciding what to do.

I don't suppose there is really very much difference between 73 Knots and 70 Knots but part of the problem is that you are expecting some pretty different things to happen between 56 Knots and 70 Knots and there isn't much room to change things. By the way, after all the confusion between Knots and MPH, WHY are we still using Knots?

- Ivan.

[aleatorylamp]

Hi Ivan,

I like your analogy to a chess game!... The thing is, I didn´t exactly know what to do, and I didn´t want to bother you by sending you the .air file again - I wanted to spare you having to inspect and test it. Thus, I opted for a performance report summary and subsequent short reports. Anyway, just in case you want to have a look, I will e-mail you the .air file.

The pretty different things that I expect to happen, are unfortunately really based on altitude, below and above the critical/rated 4300 ft, rather than the 56 - 70 Kt cruise speed -max speed range, although of course these speeds are correct for this plane.

The biggest change in the flight model, I suppose happened when I increased friction fron 35 to 100, and adjusted torque accordingly. It was then that I also moved the "hole" from 1300 to 1350 RPM in order to have a more independant control over higher revs., to be able to separate performance above and below critical altitude a little better.

So, it looks like you want me to use MPH... ha ha! That will strain my brain some more. The thing is, that the default Sopwith Camel speedometer is the only available old fashioned default ASI gauge I can use, and it is in Knots, as well as the screen top-line red-letter read-out... and my brain!
To be more realistic, I could of course use a custom KPH variant of this gauge, which exists, but KPH would mean even less to most simmers than Knots. For that matter, I could also use the MPH variant, which exists too, but that would also be unrealistic. So, I thought I´d stick to Knots....

OK then. The .air file I´m going to e-mail just in case, is the one corresponding to the last performance report after the friction increase to 100.
Cheers, and thanks again for your guidance.
Aleatorylamp.

[Ivan]

Hello Aleatorylamp,

One of my test pilots did a pre-flight and then took the Giant aeroplane up for a few short flights.
He came back muttering something like "Handles like a HUGE truck...." but then again, he generally doesn't fly anything bigger than a heavy twin.

I think I need to send that fellow back to do some flying on the Eindecker so that he can understand how the older aeroplanes performed.
I forwarded you his report and recommendations. Even he agrees that he needs a bit more time to evaluate the Giant.

Use MPH or Knots or anything else you like. I will just convert to either MPH or Feet per Second as appropriate.
I grew up with MPH and FPS, so I use those because I have a pretty good feel for what they mean.

I am not sure if I agree that the biggest change was the Friction / Torque adjustment. I believe the biggest change was getting the 14 foot propeller to actually work....

My son wants the computer now.
- Ivan.

[aleatorylamp]

Hi Ivan,

It is actually a big duck, but reputedly quite a manoueverable one!
MOI´s and cross-inertia were inherited from the original FS98 aircraft .air file, so I presume CFS1 has a different sensitivity to those entries and it seems that MOI´s are generally higher in FS98.
Or perhaps the computer I´m working on is too fast and distorts the flying sensation? The frame-rates per second i get are at about 65.

Thank your test pilot very much indeed for testing the Giant and for providing such extensive feedback. I´ll be looking at each point on the list and comment on them when done.

The engine and prop sections of the .air file are an excellent piece of work! With my comment on the biggest change being the friction/torque adjustment, I meant the point where the "blind chess game" started, after your mechanics and specialists had already sent the huge wooden propeller and the brand new engine and my recently graduated mechanics were adapting 4 of them to the Giant.

OK, then!
Cheers,
Aleatorylamp

[Ivan]

Hello Aleatorylamp,

Please go back to Post 1028. There is a bit of very useful information there.

One of my pilot's comments was about the consistent nose down trim.
Your post suggests it Should be a slight nose UP trim if the altimeter becomes steady with reduced power:

Steps to establish Cruise setting
1. Climb to operational altitude.
2. Reduce power until aircraft is no longer climbing.
3. Adjust Trim.

Note that these steps would make no sense if the aircraft were nose heavy or became more nose heavy as speed increased.

Regarding Maneuverability:
I will have to agree with my test pilot here.
The controls will need some adjustment to make this Big Duck qualify as maneuverable.

- Ivan.

[aleatorylamp]

Hi Ivan,
OK, thanks, I understand. I think I´ve improved the nose-down thing with the Pitch at AoA=0 parameter.

The purchase on the controls is also better now, by duplicating the moments for elevator and rudder, and triplicating the aileron one. I think it is more manoueverable now, without being too much.

Then the matter of the "C" for Chase View Window - that works only until Padlock Mode is activated. This is the bug you are referring to I believe, which you say can be cured with SCASM, which I don´t know how to use.
So, what would be better? Eliminating the virtual cockpit parts and placing that view (pilot´s position in the .air file) further aft and use that as Chase View, (and also using the 7 parts elsewhere in the plane, like two mechanics´ silhouettes in the engine nacelles), or perhaps kindly requesting someone to help out with SCASM there? More bother, I´m afraid...

Cheers,
Aleatorylamp

[aleatorylamp]

Hi Ivan,
My idea didn´t work - which I´d more or less expected... and you already know, I´m sure. Eliminating the internal view designated virtual cockpit parts didn´t help - they disappear anyway with the Padlock on Chase View. It´s other things that block forward vision - like the top of the Nose structure, and with rear view, it´s the inner parts of the rear fuselage. Virtual cockpit eye-point has nothing to do with it either, as I found out, and as you know already...
So, you said SCASM cures that. If it´s not too difficult, I suppose I could learn...
Cheers,
Aleatorylamp

[Ivan]

Hello Aleatorylamp,

I don't have a solution for the cockpit interior view. I know how to modify them, but I have basically been following a recipe I got from Hubbabubba a few years ago. It is a heavily modified recipe, but that is where it started.
For SCASM stuff, he is certainly a better source for advice.

As for the issue of maneuverability, there are a few ways to handle it.
You obviously can't make the control column require more force to move because it is only a little plastic thing wired to your computer.
Sometimes reducing the control response will give the proper illusion.
Sometimes modulating the control effect works.
(The control effect is very good and nearly linear to start. It hits a peak or its effect increases more slowly with increasing deflection.)

- Ivan.

[aleatorylamp]

Hi Ivan,
Normally, with hollowed out, windowed cabins there is no need for making extra internal-view-tagged parts for a virtual cabin, as the cabin parts themselves provide a decent internal view, but with this plane, the cabin is a solid block, and only 7 Internal View tagged parts are free for a virtual cockpit, and this doesn´t work with Padlock on...
To improve manoueverability, it is going very well at the moment by increasing the control moments, so that will be another problem out of the way! I´m also writing checklists, which are always nice to have.
Anyway, slowly it´s coming along.
I´ll keep you posted!
Thanks and Cheers,
Aleatorylamp

[aleatorylamp]

Hi again!

With the Giant failing to compile after 142.4 % degree of complication, I have just discovered that by un-texturing the shaded cabin-side and roof windows (top and side textures), it has gone down and although it won´t allow the main wheel-hubs to have the front-wheel textures, it does allow two mechanics´ head silhouhettes to be put into the engine nacelles, using side applications of the front and rear gunners´ faces. The degree of complication is at 142.9% now, with 1143 parts

Edited Update: I´d thought for a moment that the lower AF99 degree of complication would allow doubling the front and dorsal MG´s, as some units had those, but there is no way I can free the resources. The guns appear to have been captured twin Lewis guns, so it doesn´t matter anyway.

So, I wonder which is better: The perhaps the strangely shaded, textured windows, or the simple 2D textured mechanic´s heads peering out of the engine nacelles - I can´t decide! What would a Simmer prefer?

Cheers,
Aleatorylamp

[hubbabubba]

Sorry guys!

Ivan just send me an e-mail about the "Giant" that I could not have possibly missed. Well, guess what; I've missed it!

The problem is that I'm using an RSS feed to keep in touch with latests threads, and "Conspicuous by Their Absence" is not fresh, to say the least.

Aleatorylamp, I will read your PM and respond to it, but, in the meantime, you should read my "series" of HTML tutorials at NoDice site; to be found HERE. This will give you a good basis for further conversation.

Thanks for the heads-up, Ivan. Otherwise, the obvious would have passed just under my nose!

[aleatorylamp]

Hi all!
Not to worry - OK, thanks a lot.
I got a lot of stuff down from the site to study and I´ll do my homework!
Cheers,
Aleatorylamp

[Ivan]

Hello Hubbabubba,

I was thinking that a quick lesson in how to set up a V Cockpit using SCASM like what you sent to me back in 2006 would do Aleatorylamp quite a lot of good.

- Ivan.

[aleatorylamp]

Hi again,
No hurry with SCASM, my homework is very abstract, and I have to do the most basic thing as yet, which is to see how I can start the SCASM program first (the one that comes with Airport 26).

Then, I´ve also been looking into the DP tutorials as well, which are more understandable. As this plane was the equivalent in those days of a flying fortress, and all crew positions were armour plated, it may be worth while my thinking of the life points for the different sections of the aircraft.
Also, of course, flying Quick Combat against 2 Spitfires and 3 Mosquitoes is a bit unfair. A Sopwith Camel and a Vickers Gun-bus and perhaps a Voisin L5 would be better, but the question is how will the rear gunners hit them? Does CFS1 shoot really sideways and backwards as defined in the DP files? The plane is not really all that manouerverable so as to hit them all only shooting frontwards.

Anyway, thanks to Ivan´s SCASMing the virtual cockpit, the first Giant (Zeppelin-Staaken R.VI, built by Schütte-Lanz with twin tailfins and Mercedes engines) model is finished! Fantastic! Once the firing power and life points are decided, I suppose it will be ready for uploading.

As Ivan predicted, the SCASMed V-cockpit has left me with free parts to allow a central tail-fin and rudder for a three-finned Staaken-built version (with Maybach engines and darker blue night-bomber textures), and the model itself is done too. I´ll have to learn to SCASM it for the V-Cockpit. No hurry though, I have still to make the new textures and engines, 245 Hp rated at 8200 ft and 1400 RPM.

Cheers for now!
Aleatorylamp