1 Attachment(s)
About Two Hours Later - P-39CEJ
One of the very nice things about not significantly changing the shape of Eric Johnson's model is that just about any of the other paint jobs will fit onto my modified model without a lot of work.
The canopy frame section maps onto a different texture file and that needed some slight editing but it was not difficult.
The missing textures (that I added to prevent multiple pieces mapping to the same files) came from the D model.
The DP file was also lifted from the P-39DEJ with the maximum ammunition load for the .50 caliber cowl guns reduced from 270 rounds down to 200 rounds. I do not know if this is accurate, but I have not seen any references list anything more for the P-39C.
Also, there needed to be some room in the nose for the 600 rounds of .30 caliber ammunition.
One Wing Gun Station was deleted and the other was modified to become a Nose Gun Station with firing rate of the guns reduced from 1200 RPM to 950 RPM to account for synchronization losses.
Unfortunately on my first pass through the DP, I neglected to delete the bomb load.
I do not believe the P-39C was equipped to carry a bomb.
The Damage allowed for various systems also has not been reduced from that of the P-39DEJ.
The P-39C had unprotected fuel tanks of 85 Gallons capacity which were replaced by self sealing tanks on the P-39D and capacity was reduced to 60 Gallons each.
This meant that the fuel tanks on a P-39C were probably very similar in vulnerability to those of the typical unprotected Japanese Zero Fighter.
Data for updating the AIR file came from Detail & Scale Volume 63:
Empty Weight 5070 pounds
Gross Weight 7180 pounds
Maximum Take Off Weight 7300 pounds
From these weights, it is clear that the P-39C could not carry any significant external stores.
Bell also had a tendency to list Gross Weight with only a partial fuel or ammunition load.
My belief is that the 7300 pound Maximum weight is with full stores and 7180 pounds is not.
From this maximum weight and deducting all the removable stores and a portion of the engine oil (90.75 pounds),
the AIR file weight should be around 6065 pounds.
- Ivan.
3 Attachment(s)
Something Removed - Something Added
The overall appearance of the paint scheme for the P-39 BMC was what attracted me to begin with but there are a few details that are not quite right.
The First Screenshot shows Blue lines on the carburetor scoop behind the cockpit.
I believe these lines are on the edges of the textures of the aft fuselage in order to create blue highlights.
The bluish colour can be seen at very shallow angles. It is a technique I have used in models in the past.
This also shows why having different objects map very close in the same texture file may not be a good idea.
If the colour is different between the objects, there may be an unintentional highlight.
Generally a margin of about 3-4 pixels seems to avoid this problem.
The problem here is that the Carb Scoop maps to the same texture as the upper aft fuselage and the highlight technique cannot be used there without causing some side effects.
The other item worth noting in the First Screenshot is the NACA style scoop and vents that are located just behind the propeller spinner. These were features that were added to late model Airacobras and did not exist on the P-39C.
The Second Screenshot shows some texture changes to the underside of the P-39C.
The "U.S. Army" was lifted directly from the P-39D and of course the mapping is identical.
The Exhausts for the central Coolant Radiator and side Oil Coolers has also been added near the trailing edge of the wing.
This image also shows a problem with the dimensions of the 3D model.
The Wing Root intakes feed air to the coolers in the belly of the Airacobra.
This was one of the problems of the aeroplane: There wasn't room for any larger radiators or oil coolers as engine power increased in later versions, but it WAS a very clean and low drag installation with nothing projecting out into the airstream.
The inboard intakes feed the Coolant Radiator and the outboard intakes feed the Oil Coolers which are directly in line behind them.... About where the Wheel Wells are located in this model.
The Wheel Wells are located too far inboard in this model. In reality, most of the Wheel Well was located in the detachable outboard Wing sections with just a small section including the inner Gear Doors in the wing center section.
The Third Screenshot shows the P-39CEJ after a fairly quick SCASM treatment to remove Wing Guns, and Antenna Mast.
Actually the Antenna Mast was repurposed to cure bleed with the Carb Intake Opening. This was a bleed that I had not noticed when the intake and opening were both dark as on the P-39D.
The "proper" way to fix this is in AF99. The more interesting way to address the issue is with SCASM edits.
- Ivan.
2 Attachment(s)
Editing the P-39D as well
The P-39DEJ also had the same disappearing Carb Intake problem but the solution of repurposing the Antenna to cure the bleed obviously would not work. We need the antenna mast there.
The quick solution was the SCASM equivalent of adding a Glue Part and duplicating the Intake Opening.
The First Screenshot shows where the Intake Opening would normally disappear (fixed via SCASM).
The fuselage colour is changed so the opening is more visible.
The Second Screenshot shows where the AF99 Glue Part would go to address this problem.
The Part is larger here so its location is obvious. I should put this into the Project so that the change becomes permanent and is picked up in any further re-compiles.
- Ivan.
Bell P-39C Airacobra EJ.zip
http://www.sim-outhouse.com/soh_ftp/...6013264544.jpg
A new entry has been added to Add-Ons Library, category CFS 1 Aircraft Add-Ons
Description: The Bell P-39C was the first production model of the Airacobra. It was more lightly armed than later models and carried no armour or self-sealing fuel tanks. It was used for initial service trials and often was not equipped with its cannon. Because of the lack of protection, it was deemed unsuitable for operational use and twenty that were produced were sent to training units.
This particular project uses a hypothetical paint scheme by Indianola Flightcraft and Eric Johnson and uses an extensive rework of Eric Johnson's P-39D AFX for its visual model. The Flight Model, Damage Profile and Control Panel are all newly built for the project.
This project started as an experiment to see what performance differences resulted from the addition of equipment and armour in the later P-39D. When I came across the Indianola paint scheme, it seemed to make a perfect contrast to the olive drab P-39D. (In reality, the P-39C wore the same typical Army Air Forces olive drab paint.)
Many Thanks to Mr. Eric Johnson for making his AFX freely available for experimentation.
Let me know what you think of this project.
- Ivan.
To check it out, rate it or add comments, visit Bell P-39C Airacobra EJ.zip
The comments you make there will appear in the posts below.