New Gotha bombers series thread

[aleatorylamp]

Hello Folks,

The layout of the G.1 Ursinus design not only allowed bombs to le loaded more easily under the lower wing, but also offered a clear field of fire all-round from the top. The attached scan shows that contrary to what I expected, the pilot sat in the rearmost seat, not in the middle. I don´t know how accurate this drawing is, as the rear seat would allow a better defence of the lower rear.

Update Confirmation on 2nd Gunner´s position: I checked, and in effect, it seems that in case of a second gunner, he would be placed in the middle.

Update on rudder shape:
On this drawing I corrected the rudder. Originally it showed a rudder which went down lower than the elevator, and was horn-balanced underneath. This way it would have had a smaller elevator between the rudders, with 2 small elevators on outboard sides. I have only found one photo with these rudders, but it refers to an improvement in the G.I design which was not produced in any numbers and apparently did not see any service. Photos of production aircraft all only show rudders slanting upwards to make space for elevator movement.

Anyway, the attached drawing shows the bombs: It can be seen that bombs were not only loaded under the wing. There are photos showing two hanging from the nose in the front. They also look fatter than the slim French hand-bombs, and look heavier.

Update: Bomb weight correction.
After further research, it seems bombs were 20 Kg bombs. How would the 330 lb (150 Kg) bombload have been distributed?
Perhaps 7 x 20 Kg. (5 under the wing and 2 x 20 Kg at the nose), althought that would make it only 140 Kg...

I wonder if anyone knows if there is a 20 Kg bomb .bgl with this shape.

Another question:
Regarding the .air file, it appears that one thing is how the plane flies as a piloted plane, with the CFS1-type airfile (rather than a mere FS98 one where all the engine needs is an entry for Hp), and another is how it flies as an AI plane.

Does anyone know about AI flight dynamics? I suppose it would also need tweaking the Dp files with more boxes for more detailed damage points. The Gotha series apparently was not easy to shoot down, so it would be useful to keep that in mind too.

Cheers,
Aleatorylamp

[aleatorylamp]

Hello Folks,
I´ve managed to get a good CFS2 .air file for the Gotha G.1 Ursinus!

Specs mention the 160 hp Mercedes D.III class 3 engine in military use, on the Gotha G.I,
as giving a maximum sea-level (500 ft) performance of:

81.25 mph with 172 Hp at 1420 RPM.

So far, I´ve managed to get the model very close:

82.3 mph, with 173 Hp at 1423 RPM.

The process is quite interesting, and I thought it was worthwhile to share on the thread.
I learnt how to do it thanks to Ivan from the CFS1 Forum, who patiently explained things I
didn´t always fully understand, how the airframe aerodynamics, the engine parameters and
the propeller parameters interact in the .air file. With time the pennies started dropping!

Then, there´s the conversion to CFS2, of course, and all the CFS1 performance has to be
adjusted again.

First I made a basic CFS1 .air file for the model to have a starting point.
Apart from the usual weights and dimensions, it needs data input for things like cylinder displacement,
compression ratio, propeller diameter and maximum. and minimum pitch angles (fixed 25-degree pitch for
the Gotha G.I). Also, convenient adjustments had to be made to the 25-degree pitch propeller graphs.

AF99 models compile directly into CFS1, and animated. Here the model file is processed first by TEX512,
to convert .xaf textures into .bmp format. This facilitates future enhanced texture repaints.
Then it is processed by the Model Patch, which makes weapons and crew visible in CFS2 when they are
added with Dp.

Ravenna and Kdriver helped me to learn how Dp fileswork.
It´s amazing what Dp lets you do, even as a beginner like me.

CFS2 needs a different Aircraft.cfg file, similar to the FS2002 one, but easier.
From the FS2002 Gotha G.I Aircraft.cfg written by FSAviator in november 2002, I copied the sections
needed by CFS2 into the new CFS2 Gotha G.I Aircraft.cfg.

Now comes the CFS2 tuning for the .air file, as the CFS1 .air file comes out with twice the power and
performance. This is where it gets interesting. I´m slowly getting a better at the balancing act between:

- Engine Torque and Friction Graphs.
- Propeller Efficiency and Thrust Coefficient Graph Tables,
- The three Drag entries in the Primary Aerodynamics Section,
- Wing characteristics.

ALL OF THESE affect Engine Horsepower, Engine RPM, and Aircraft Speed.

I can only do fixed-pitch propellers, or perhaps two-pitch ones, because they are easier. They only
use one of the 12 graphs in the graph table, whereas with constant speed propellers, you need to work
on quite a few more, in the range of pitch angles for a given CV prop.

Here are some screenshots of the different graphs. The propeller graphs show, enhanced with yellow boxes,
the single 25 degree pitch angle graph used by the Gotha G.I .air file.
You can see how I was experimenting with 20 and 30 degree pitch angles as well.

My propeller graphs are different from the ones that come with stock aircraft. The shape of the downward
slope on the right is more like the real ones. It appears that otherwise you get something like perpetual motion,
and also, it is difficult to get anywhere. It also seems to be important that both graphs cross the Zero point
at the same place.

This place depends on the circular speed at which the propeller blades corkscrew through the air, known
as the "J" factor. It depends on engine RPM, propeller diameter and Aircraft speed. Each graph in the graph table
represents one pitch angle. Each column is a "J" factor, and represents an aircraft speed.

Well... for example:

Importing the Gotha G.I CFS1 .air file into CFS2, I got way over 120 mph (I didn´t bother to find out by how much), with 305 Hp at over 1500 RPM.

So....

Step 1:
-------
- Reduce the Torque graph, and perhaps increase the Friction graph. This will reduce power and slow down the
engine (and consequently also the aircraft).
- Increase Zero Lift Drag to further slow down the aircraft. Once you get more or less the Hp and Speed you
want, you will see that RPM is too low.

Step 2:
-------
- Lower the Thrust coefficient graph (only for 25 degree pitch in this case). This will reduce the power
required by the propeller, and increase the RPM. However, Horsepower and aircraft speed will also rise.
- Reduce Propeller efficiency to slow down the aircraft. This may affect RPM and Horsepower too.
- You will probably need to re-adjust Drag, depending on the result.

Note:
-----
Zero lift Drag increases slow down RPM so parasitic or induced drag adjustments may help - or even
landing gear drag in case of fixed-gear aircraft!

Note:
-----
Reducing aircraft speed also reduces RPM.

Further Steps:
--------------
Depending on the result, make further small adjustments to the Thrust Coefficient graph.
If RPM is still too low, further apply minute reductions to the 25-degree Thrust graph.
If speed gets too high, make small reductions to the Propeller efficiency graph.
Simultaneously you may need to re-adjust Drag.

And so, go round in circles until you see that you are getting closer to what you want.

Important note:
---------------
I am by no means an expert, just a hobbyist who thinks he is learning something useful.
I´m sure there are others who are much better at this than myself.
Therefore, should I have made a stupid or erroneous statement, do tell me, and I will rectify!

Acknowledgements:
-------------------
>>>> Thanks to Ivan of the CFS1 Forum for showing me this, without which I would still
be making FS98 .air files. For these, all you need is a Horsepower entry, a propeller
diameter entry, a maximum RPM entry (I think), and a Zero lift Drag entry. You can forget
about cylinder displacement, engine torque and friction, and propeller graph tables!! But, it´s
not so much fun, and if you need a supercharger or a turbocharger, you can´t have one, so there! ;-)

>>>> Thanks to Ravenna and Kdriver for helping me out with the interesting Dp files, and with
other fascinating CFS2 delicacies like TEX512 and MdlPatch!

>>>> Thanks to simmers who have had the patience to read upto here!!

Cheers,
Aleatorylamp

[aleatorylamp]

Hello All,
In my post #76, I came to the erroneous conclusion, that the G.I with a different rudder shape on one of the drawings I had, was a newer variant which never saw production.

In effect, it wasn´t a newer variant, but the original 1915 Friedl-Ursinus Grosskampfflugzeug (large battleplane) prototype (whose rudder did not see series production).

Although the original design was for a float-plane, the prototype presented to the military for evaluation was a land-plane built by Oskar Ursinus and Helmut Friedl, equipped with 2 x 100 Hp Merdeces D.I engines.

This was before Gothaer Waggonfabrik acquired the license to build 18 Gotha G.I units, plus one Gotha G.I Ursinus Wasserdoppeldecker (Water-biplane), which saw WWI service two years after it was originally designed, and was apparently based in Zeebrugge on the Belgian coast.

Thanks to Ravenna and Kdriver for indicating the sources of this corrected information!

I also dug out my FS2002 model of the Gotha G.I Ursinus Water-Biplane, after to queries by Ravenna, and then
thought that as the Gotha G.I Ursinus design had originated as a biplane on floats, it would be interesting to
be able to try one out in CFS2, correspondingly updated and upgraded.
So, in due course, the Gotha G.I UWD will also acquire a new life!


Incidentally, both the FS2002 Gotha G.I, and the G.I UWD flight dynamics were written by one FSAviator, and had very realistic and well-balanced flight behaviours. They readily convert directly into CFS2, once engine performance is sorted out, so they do fly very well indeed!!

Cheers,
Aleatorylamp

[Ravenna]

Stephan, I just love the WWI German classifications for aircraft types. Wasserdoppeldecker and einsitzcommando are such visual classifications!

[aleatorylamp]

Hello Folks,
I was just inspecting some other Gotha twin-engined model biplanes I had built for FS98 years ago, and I found two other large, twin-engined water-biplanes, the Gotha WD7 and WD14.

In the case of the WD7 model, gunner´s well and pilot´s cockpit are already hollowed out, but this is not the case of the Gotha G.I, the G.I UWD, and also the Gotha WD14, whose gunner wells and pilot´s cockpit are only flat dark-grey disks, and which will require considerable work and time until they are ready.

So there is a slight change in plans.
I´ll be preparing the Gotha WD7 first, as it is now ready for conversion after combining the submerged portion of the floats with the un-submerged portion (CFS2 won´t need submerged elements to disappear below a certain speed for water landings). It only needs a CFS2 .air file, which I will base on the similar Gotha G.I Ursinus Wasseredoppeldecker.

Here are two screenshots. It is quite an interesting looking machine!

The Gotha G WD-7 was the first twin-engined seaplane ordered in quantity by the German Navy although only eight were completed. It was designed by engineers K.Rösner and A.Klaube of the Gothaer Waggonfabrik.

The prototype flew in 1915 and was allocated the marine number 119, the small production batch being numbered 670-676. It was also the first aircraft to be produced in any quantity by the Gothaer Waggonfabrik.

The WD-7 was employed for general marine reconnaissance at first, and later mainly as a trainer for the larger twin-engined WD-14 torpedo bombers that operated in the North Sea and the Baltic. The WD-7 was made of wood and fabric,
and powered by two 120 hp 6-cylinder in-line, water-cooled Mercedes D.II engines, being capable of a top speed of 69 kt.

Cheers,
Aleatorylamp

[aeronca1]

Any updates on the G.V and G.Vb?

[aleatorylamp]

Yes, I can update information as to how things are progressing, but the models are not quite ready yet.

The intention is to supply a G.Va as well, with nose-gear and night textures, and it is in the making.

I had thought the G.V and G.Vb upgrades were ready, but during the G.Va texture trials, our texture expert
reported problems. The way I had mapped the G.V and G.Vb textures, caused texture-repetitions on the
planned G.Va because of a mid-fuselage symbol it has on the sides. This requires some texture re-arrangement.

Inspecting the problem, I also found some extra very odd texture-mapping deficiencies elsewhere, which I am fixing
first. I don´t want to knowingly upload upgrades with flaws that I know I can fix.

This kind of texture work is a bit heavy, so I have to do some other in-between things just for a change.
Also, I have had to see to some health issues, but nevertheless, the conveyor belts are full, and the factory is busy.

New update: My factory manager has just informed me that the G.V has had its hexagonal lozenge pattern re-applied, and the workers are at present checking everything while the glue is drying.
Then they will apply all the texture re-arrangement, re-mapping and corrections to the G.Vb which is waiting at the other end. Once this is done and checked, the G.Vb will be dispatched, and the engineers will convert the model into a new G.Va, installing the new nose-gear, eliminating the Stossfahrgestell, and new night textures will be applied.
Let´s see if they can do it!

Cheers,
Aleatorylamp

[aleatorylamp]

Hello All,
The English bomber equivalents of the "Grossflugzeuge", the DeHavilland Amiens and the Blackburn Kangaroo, which are being upgraded, will be released in due course. They still require some work on the textures.

Thanks to Ravenna I have been able to see some new documentation which clarifies some doubts I had on the DH10 and DH10A DeHavilland bombers, mainly with respect to the colour scheme, so that is being seen to.

Neither hurry nor pause...
Cheers,
Aleatorylamp

[Ravenna]

Stephan, would I be right in thinking that today is a special day in your corner of the World?

[aleatorylamp]

Hi Ravenna,
Yes, the regional festivity - To your health too!
A holiday tomorrow for some - my daughters and my wife have exams to study for, but I´ll sleep in!
... and make some planes too.................
Why aren´t there any biplane icons?

Cheers,
Aleatorylamp

[aeronca1]

Thank you for the update!

[aleatorylamp]

You´re welcome!
The G.V will be finished very soon.
Cheers,
Aleatorylamp

[aleatorylamp]

Hello all,
The G.V and G.Vb are basically finished, and are at present being checked at quality control - for stress tests and texture mapping issues. Let´s see what happens next!
Cheers,
Aleatorylamp.

[Ravenna]

Very happy with flight characteristics in free flight. I've not tried her as an AI yet. It takes some time to gain altitude with a full load but that's to be expected. Well done!

[aleatorylamp]

Hello Ravenna,
Thanks for the feedback. I´m glad you like the handling.
Fully loaded, after take-off they circled upwards, slowly gaining altitude, as with the throttle gated high-compression engines they had less power at low altitude.

These FD are very good - in 2007 they were written by one FSAviator and then, a few years ago, Ivan of the CFS1 Forum did the graphs so that only about 70% power is avalable until rated altitude (1300 metres). I only adapted engine performance to CFS2.

The performance is basically the same as the G.IV. The G.V was aerodynamically better, but heavier, so at the end they were the same.

Cheers,
Aleatorylamp

[aleatorylamp]

Hello All,
Martin Klein has made some wonderful night-bomber textures corresponding to G.Vb unit 953/18.
These have been adapted successfuly on the model after some texture mapping corrections.

Now I´m just doing the checklists and putting in the Stossfahrgestell into the Aircraft.cfg so the
model won´t nose-over in the sim, which was the whole point of having the added wheels in
the real model.

While I finish, here are some screenshots. There is also one of the excellent new panel made by
Kdriver, showing the equally excellent new Gotha Gauges made by Martin Klein.

Cheers,
Aleatorylamp

[aleatorylamp]

Hello Folks,

The same as with the G.Vb, I´m finishing the checklists, the Readme, and it still
needs its registration number.

It will have the same panel as the G.Vb, and here are two screenshots showing
the machine in conspicuous hexagonal anti-friendly fire lozenge colours.

Cheers,
Aleatorylamp

[Ravenna]

Lovely work. It just keeps getting better!

[aleatorylamp]

Long live AF99 !!

[aleatorylamp]

Hello Folks,
The Gotha G.V series upgrades/updates are taking a bit longer to finish than originally foreseen.
One improvement led to another, and several additional ideas suggested by Kdriver and Ravenna spurred
more experimentation to strive for still further improvements, and it almost never stopped!

In this interesting process, it soon became apparent that thanks to CFS2´s "Z" Buffer, this simulator allows models to be built with a more efficient use of components. These can be combined in different ways, enabling a more detailed build. One never stops learning!

Also, after much research, Martin Klein has come up with several very elaborately and beautifully created liveries for each of the three different models, so some previous colour schemes have been abandoned.
Martin´s new liveries required some modifications on the models because they demanded different texture mapping techniques, which eventually also contributed to further improvements on the models themselves.

Here are screenshots of the new G.V, G.Va and G.Vb models in the different liveries to be uploaded, as an illustration of our progress. A few details still have to be ironed out, e.g. Dp files and a couple of other minor things, and the upload is not far off!

Cheers,
Aleatorylamp

[Ravenna]

The best dressed Geschwader in the OHL!

[The B24 Guy]

Hi aleatorylamp,

Great looking improvements.

Regards,
B24Guy

[aleatorylamp]

Hello Folks,
Thanks! The few remaining minor touches will expectedly not be too long!
Cheers,
Aleatorylamp

[aleatorylamp]

Hello All!
The finishing touches have been done, and Ravenna has kindly given me a hand with the Dp files,
that were giving me a headache with all the numbers...

Here are some screenshots to show the bombloads, as well as Martin Klein´s expertise with some
of the incredible textures he created.

Shown are G.Vb in conspicuous daylight livery, "Princess Peach" as we baptized her affectionately,
all bombed up ready for take-off, then the awe-inspiring G.Va fire-breathing "Dragon" going on a mission,
then beautiful G.V "Cassiopeia" flying through a storm, and another G.V, the "Snake", patiently waiting in the rain.
This last screenshot also shows other improvements, like Martin Klein´s radiator, and Kdriver´s engine texture.

Moreover, Kdriver and Ravenna have been test-flying the creatures, to check their airworthiness.

I´m just polishing off the Readmes, and the uploads shouldn´t be too far off!

Cheers,
Aleatorylamp

[Ravenna]