Grumman F7F Tigercat, 1st Production Version.

[aleatorylamp]

Hello Folks,
A new thread, a new project.
This time, quite an exciting one, I hope.

The Grumman F7F Tigercat was one of the highest performance piston-engine fighters ever built.
It was introduced in 1944 and deployed by the U.S. Navy and the U.S. Marine Corps untril 1954.

One Navy test pilot said "It´s the best damn fighter I´ve ever flown".

According to quite a few, the Tigercat was just about the wildest plane in the Navy and the Marine Corps at the time. About 10 flying examples survive today, and are prime attractions at airshows.

WEP Power on this Tigercat was 2x2400 Hp at 2800 RPM, and at 1000 ft, it did 400 mph.
RoC was 4360 fpm. That sounds pretty darn wild, and that is in part what will make it quite a
fantastic model to build, I wager. Another important factor, is its beautiful and elegant design.

The .air file will obviously be quite challenging, but could be made easier by basing the engine parameters on some existing material. The 1st production model Tigercat´s engines seem to be quite close to the engine on the P47d, so that one could be souped up just a little to meet the specs.

Propeller size seems very similar too but with 3 blades instead of the 4, which would account for the 100 revs higher maximum RPM. Ceiling was 36200 ft and Critical Altitude 19200 ft, lower than for the P47d, so the supercharger will need a some adjusting.

In the next few days I´ll turn the 3-views into some 2D AF99 templates for the basic shape-layout,
to get a platform for a first version of the .air file.

Cheers,
Aleatorylamp

[gman5250]

If I can be of any help I'll be happy to share data from my FSX/P3D F7F Tigercat project i.e flight models/dynamics, background data, etc.
Feel free to PM or just post up. I'll follow the thread.

[aleatorylamp]

Hello All,
As I mentioned before, there is a glue problem at the engine nacelles, where outer
flaps and central and outer wing sections must be glued. Upto now, all wing/flap/nacelle
elements are in Wing Mid left/right.

However, there IS a combination with another group that offers a little improvement.
Splitting the sequence in two, and combining it with Inner Wing Mid left/right, it improves:

Wing Mid left/right now only groups outer wing/flap elements (central wing sections,
outer flaps and outer wings).

Innerwing Mid left/right now groups inner wing/flap elements, engine-nacelles, and the
little wing-top convexities.

Flaps now display properly, both retracted and extended, and the wing-top convexities too.
However, as AF99 now uses automatic glue between the two groups, there´s a slight,
momentary bleed between nacelles and central wing sections.

Nevertheless, it all looks much better, and quite promising...

Update: I tried using separated inner and outer nacelle-half components again, this time
in the new glue sequences mentioned above, but it only brought back the previous
flap/nacelle bleeds.

So, the lesser evil seems to be the momentary outer nacelle-wall bleeding through the wing
when viewed from vertically above, which is not a commonly used viewing angle anyway. Also,
with the dark-blue colour scheme on this model, I suppose this small flaw will go largely unnoticed.

I´ll get on with the wheel wells and doors now, and then start on the textures.
More, later...
Cheers,
Aleatorylamp

[aleatorylamp]

Hello ********,
That is very kind of you, thanks very much!

I believe the P3D version of the Tigercat is also with the sleek, radarless nose.
If you have a complete set of specs for the engine on it, that would be great,
and maybe a colour scheme if possible.

The main reason for my wanting to make the -1 or 1st Production Version, apart
from the 2400 Hp engine, is that I found the performance sheet for it, but some
technical details are lacking, like Manifold Pressure for the different performances
(Normal, Take-off, Military and WEP), so a later version with more info would also
be very much in order.

P.S. I just saw your thread. Your model certainly looks impressive!

Thanks again,
Cheers,
Aleatorylamp

[Milton Shupe]

I have quite a bit of docs available from my initial project of the -1, 2, 3, 3N.

I'll pull some together and zip it up for you shortly.

Meanwhile:

F7F Tigercat
Specifications
Primary Function Fighter aircraft
Contractor Grumman Aerospace Corporation
Propulsion Two 2100 hp Pratt & Whitney R-2800-22W or -34W
Length 46 feet 10 inches
Height 16 feet 7 inches
Maximum Take Off Gross Weight 25,720 lbs
Empty Weight 16,400 lbs
Wingspan 51 feet 6 inches
Maximum Speed 435 MPH
Range 1,260 mi
Armament Four 20mm cannon in wing roots, four 12.7mm machine guns in nose, one torpedo under fuselage, 2,000 lbs. of bombs


General characteristics


* Crew: 2 (pilot, radar operator for the 3N)
* Length: 45 ft 4 in (13.8 m)
* Wingspan: 51 ft 6 in (15.7 m)
* Height: 16 ft 7 in (5.1 m)
* Wing area: 455 ft² (42.3 m²)
* Empty weight: 16,270 lb (7,380 kg)
* Max takeoff weight: 25,720 lb (11,670 kg)
* Powerplant: 2× Pratt & Whitney R-2800-34W "Double Wasp" radial engines, 2,100 hp (1,600 kW) each


Performance


* Maximum speed: 400 knots (460 mph, 740 km/h)
* Range: 1,200 mi (1,000 nm, 1,900 km)
* Service ceiling 40,400 ft (12,300 m)
* Rate of climb: 4,530 ft/min ()


Armament


* Guns:
o 4× 20 mm (0.787 in) M2 cannon
o 4× 0.50 in (12.7 mm) M2 Browning machine gun
* Bombs:
o 2× 1,000 lb (450 kg) bombs under wings or
o 1× torpedo under fuselage


Avionics


* AN/APS-19 radar

[aleatorylamp]

Hello Folks,
Slowly things are coming together, and I still have to decide on the registration number.

Candidates for this F7F-1 model are either number 99, with the number only on the tail,
and not on the wings, engine nacelles or nose, or alternatively number 01, with numbers
painted on the fin and on the nose. Possibly I´ll go for the 01.

At the moment, there´s bleed-battles between wheel doors and engine nacelles.
Wheel-wells seem OK grouped in Wing Low left/right, but wheel-doors make problems there,
despite glue templates. Similar problems also arise if grouped with the landing gear in
Gear Left/Right, with inner-doors in Gear Centre, or also, grouped in Innerwing Mid Left/Right,
glued in sequence with the nacelles.

The problems in these 3 available grouping methods seem to be caused on one hand, by the
low-reaching engine-nacelles, and on the other, by the the landing gear being positioned right
at the front of the wheel doors. So, I´ll have to see if I can at least find a lesser evil...

Cheers,
Aleatorylamp

[aleatorylamp]

Hello All,
I found a FS98 example from 1999, of the Tigercat in Navy-blue livery by Chris Lampard,
with rather good textures.

I am loosely basing the textures for the CFS1 Tigercat on these, lightening up the overall
colour slightly, adapting the texture mapping to fit, and changing the markings.

As expected, once textured, the nacelle bleeds virtually disappear, as the nacelles are
textured in the same dark-blue as the wings.

Here are some "after-before" screenshots.
The one on the right (furthermost) has the yellow-coloured, untextured nacelles bleeding
through the top wings, and the one on the left (furthermost) shows how the textures
conceal the bleeds.

So that´s one problem solved, that was still bothering me to some extent.
Even for a possible re-paint of the model in silver-grey likefor example the "Test" prototype
Tigercat, the bleeds would also go unnoticed.

Then, the centre screenshot shows texture progress on wings, fin and tailplanes.
I got the typeface correct this time!

Cheers,
Aleatorylamp

[aleatorylamp]

Hello!
Thank you for the preliminary details!

I would expect that the 400 mph would be at S.L.,the 435 mph at 3000 ft,
and the 460 mph perhaps at critical altitude.

Then, 2100 Hp seems max. power at S.L. and would be for the engine on
versions after the 1st production lot.

The supercharger must have had higher manifold pressure, so S.L. performance
was limited to 2100 Hp, not 2400, but altitude performance seems to have been
better, and the ceiling higher.

OK, no hurry with the .zip, and I´m looking forward to receiving it.
Cheers,
Aleatorylamp

[gman5250]

Much of my original data will match the data from Milton. I have worked the FM with some professional assistance to get the cruise speeds and MAP a bit more dialed in. I've also got a bit more background data to add. I'll zip mine up as well.

All of the above will most likely be of significant help to you sir.

[Milton Shupe]

127MB of data uploaded for you;

Check your PM for link.

Have fun. :-)

[aleatorylamp]

Hello Folks,
The bleed problems in this model have not been solved yet, and I haven´t made
any further progress on them, so it is still on standby. I ´ll see if i can at least
provide an improvement.
It seems I´m going to run into similar problems with the new Havoc project.
We´ll see how it goes...
Cheers,
Aleatorylamp

[aleatorylamp]

Hello Folks,
Although there is still a considerable amount of work to be done, I think the improvements so
far warrant another WIP model post.
It´s not going too badly, which is very pleasing.

The main aspect still needing work are the hairline cracks and fine adjustments of parts in several different areas of the model.
These defects are now more apparent given the dark-blue navy textures the aircraft now has.

The model is now fully textured with provisional No. 99 Navy textures, but the panelling still needs to be improved.
There were lots of adjustments and alterations made to the textures of the FS98 Tigercat by Chris Lampard, so the resemblance has practically disappeared, although they proved very useful as a starting point and guideline.

Summarizing over the previous WIP-V3, in Version 4:
-Wheelwells and geardoors have been put in, and display is reasonably acceptable, although there are still some minor bleeds of geardoors through the wing seen from above, and also through the propeller disc, although this last thing will be a bit hard to solve.
- Flaps display has been improved, and the glue sequences involved are more effective.
- The .air file has been improved a bit further as regards wheel stance on the tarmac. Suggestions as to aircraft behaviour will be welcome.
As before:
- Panel is aliased to that of P51D Mustang.
- Sound is aliased to that of the P47D Thunderbolt.

So... Those interested can have fun and play around with the model, and also have a peek inside if they are so inclined.
Cheers,
Aleatorylamp

[aleatorylamp]

Hello all,
A small but dubious improvement was a 4th grouping method, involving engine-nacelles grouped in
Wing Low Left/right and sequenced with wheel-wells and doors, eliminating the Nacelle/Door interaction,
leaving only a Gearstrut/Door one.

However, it ruined the rather nicely-working sequence achieved previously, that properly displayed inner
and outer flaps with the nacelle in-between.

Sixpence of one and half a shilling of the other...

Update - Surprisingly, quite an improvement:
I´ve just moved the gear-doors and wells from Wing Low left/right back into Innerwing Mid Left/right again,
but with a more precise glue-sequence, so this time it has worked much better!

Flaps, nacelles and wheel doors display correctly. It is a combination of the positive results of the last two trials.
Now the only a remaining minor issue is the landing gear struts shining through the wheel doors.

Expectedly, duplicating the wheel-doors into the landing-gear groups as insignia parts did the trick.
It´s not perfect on the inner wheel-door, but it will have to suffice.

Update 2 - Still not perfect:
Yet another glitch: The inner wing shines through the nacelles! There´s always the kicker, isn´t there?
So many parts in the Innerwing Mid left/right groups now, that it´s got very complicated.
Not even duplicating the engine-nacelles works... the nacelles then shine through the inner wings!

Let´s see if slowly but surely we can get what we want... Maybe some mumbo-jumbo will work.
Cheers,
Aleatorylamp

[aleatorylamp]

Hello ********,
Thanks for the dispatch of all that material. What wealth of detail!
It´s all there - all the info for all the models. Wow!
I don´t know about the Gmax buiding though... First I´ll give it
a go in my usual AF99 for CFS1, and see about Gmax after that.
I´ll study it and report back.
Cheers,
Aleatorylamp

[aleatorylamp]

Hello Folks!

At last, a winning streak in the fight against bleeds!
After several different tries at re-grouping engine nacelles and wheel-doors,
the annoying bleeds through nacelles and wings have finally gone, and the
model now good for upload.

Here are some screenshots - the wheeldoors are in bright red to make sure
I see any naughty bleeds... but it seems OK now. This will of course pave the
way for succesfull bleed-fighting with the new A-20 Havoc which is well underway
by now.

I´ll be uploading the model after I adjust the Dp files and finish the readmes.

Cheers
Aleatorylamp

[aleatorylamp]

Hello Milton Shupe, hello ********,
Again, thanks very much for the information supplied - Great!

The weather got very cold and wet here suddenly, and the day before all the wealth of data
arrived, I had become ill with a bad flu plus migraines. When I answered I wasn´t completely
there, and the next day I was out of action considerably, in effect, until yesterday. Not very nice!

The effect of this kind of thing is cognitively noticeable, and it was only just now that I realized
that Milton Shupe and ******** are not the same person! I´m frightfully sorry.

I do apologize. These things happen, and this stuff also affect my memory. I know it can get to
a point that other people can get very frustrated and offended, although I think we can preferably
laugh about it instead, I´m sure.

Anyway, to the nitty-gritty:
I´ve been delving into the information, and readily found all the missing technical data I needed!
e.g. manifold pressure for the different boosts, depending on the model, as well as fuel tank
distribution and weights, for a start.

It is interesting that the performance of the two engines that the Tigercat could be equipped
with, the R-2800-34 and -22, were essentially the same, but had different blowers, and performed slightly differently.

It was relatively straight forward to feed it into the .air file, and start tuning it. To begin with, I´m aiming to get the specified 400 mph max. speed at Sea Level, and 450-460 mph at 20000 ft.

I found that I could use quite a lot of the work I´d done on the Airacobra CV propeller experiments.
With two engines having bigger and 6 more cilinders, performance is rather spactacular, I must say!

The adjusting points on the propeller efficiency and thrust graphs correspond to slightly higher
"J" factors, and it´s going very well indeed. I´ve already got the S.L. speeds right, and now I´m regulating the boost gain to get the desired altitude performance.

What won´t be possible in CFS1, is to implement the 2-speed blower, so it will have to be a
one-speed one, and I´ll stick to the usual style of having 2100 Hp Military power in the normal
throttle lever travel, and 2400 Hp WEP with the F10 key.

So the .air file will be supplied with the cardboard WIP Nr.1 model in a few days for some initial fun.

Cheers,
Aleatorylamp

[aleatorylamp]

Hello All,

Getting a model ready for upload is not only the model, but also other things that take
some time to prepare.

I´ve just done a Tigercat look-alike panel for default CFS1 gauges. It is not exactly like
the photo-original, but that wasn´t the intention, as I wanted better visibility of the
outside world. I´ve also adapted Smilo´s a bomb aimer´s panel for a solid nose,
re-calibrated for the Tigercat´s higher speeds.
For the moment, here´s a couple screenshots of the two panels.

Then, the model has to be run through SCASM to correct the virtual cockpit chase
view, so there´s still some work left before the upload.

Incidentally, I finally managed to get into Flightsim.com, which my browser was blocking,
by using a different one, and there´s a good FS98 Tigercat there, albeit without a
transparent cockpit, so this one won´t be totally redundant.

I´ve also separated WEP in the .air file from the normal throttle lever travel, and it will
be 58 inches of mercury for normal max. manifold pressure at full throttle, with 2000 Hp,
giving 349 mph at S.L. and 415 mph at 15000 ft.

Then, pressing F10 there´s an extra 8 inches of mercury for WEP (type 2), with a total
of 66 inches of MP and 2400 Hp, giving 394 mph at S.L. and 459 mph at 15000 ft.

For CFS1´s single speed blower, this is quite a good approximation to the performance
with the 2-speed blower in the specs, and I expect it will be quite enjoyable to fly.

Cheers,
Aleatorylamp

[aleatorylamp]

Hello Folks,
I´m still going through the new information (new for me) supplied by Milton Shupe and ******** regarding the performance differences between the -22W and -34W engines, and am as yet undecided which of the two engines to use.

The different superchargers make the -34W better at altitude, and the -22W better lower down.
(I just corrected that - I had them the wrong way round).

Basically, the differences are not very large, and as the simulator is designed for single-speed superchargers anyway, only a reasonable approximation for the performance curve will be possible,
but a starting point will have to be decided. It will probably be more interesting in the sim to have more power lower down, so I think I´ll go for the -22W engines.

I also found that the propeller graphs supplied in the FSX .air file by Fliger 747 very interesting indeed - they are perfectly usable in CFS1. Anyway, I´m still testing them to see how they do thier work. For the moment, I´m still curbin altitude performance.

More later!
Cheers,
Aleatorylamp

[aleatorylamp]

The model now has a SACAM-corrected virtual cockpit, and I´ve implemented some
propeller blurs á la Ivan, and also liquidated a number of hairline cracks seen from above.

Having forgotten about the hairline cracks seen from below, I´ll have to catch those now,
and SCASM the model again before I upload it.

Also, after some extra trials, there are now two P&W R-2800-34W engines installed, instead
of the -22W ones. These deliver 300 more Hp each, and push top speed at critical altitude up from 430 mph to 460 mph, without affecting performance lower down, which is excellent.

This makes it into a very pleasing power-house to fly, and the model itself is fortunately
progressing very nicely after this long lull period. It won´t be long now.
Meanwhile, here´s some more screenshots.

Cheers,
Aleatorylamp

[aleatorylamp]

Hello all,
The treasure trove included a WEP performance curve for the P&W R-2800-22W for a number of loading conditions, and I selected the pure fighter version.

The first thing I noticed was that the generally quoted 455 or 460 mph max. speed don´t seem to apply to this version, and correspond to later models, the F7F-3 or -4, that also had improved altitude performance.

The performance graph clearly shows the two bulges corresponding to supercharger speeds. Low blower manifold pressure is at 58 Hg, identical to that of the -34W engine for WEP, although aircraft performance there is different - 359 mph max. speed at S.L. instead of 397 mph. (There is also a WEP performance curve for the -34W engine on the F7F-3N).

For WEP, the -22W has Low Blower at 66 Hg, and High Blower at 60 Hg,
and the -34W, has WEP Low Blower at 65 Hg, and High Blower at 66 Hg.

As we can only have one in CFS1, for the moment there is excessive speed, I left it at 66 Hg for both, which is just as well, because even so, in the High-blower section of the curve, performance is a bit low - 344 mph instead of 383 mph, but this isn´t too bad.
Anyway, attempting to correct this would give too much power at mid and low altitutude.

The biggest issue is between 5000 and 22000 ft, with a peak at 15000 ft showing a 40 mph excess.

This would incidentally be perfect for a F7F-3N or -4N - but doesn´t apply here.

My next endeavour will be to sculpt this part of the curve by adjusting the propeller graphs just
above 422 mph, perhaps at "J"=2.02.

The strange thing I fail to understand, is that although Critical Altitude is specified at 19200 ft, the 66 Hg WEP manifold pressure quoted for S.L. steadily falls until it is at 43 Hg as 12000 ft.

I thought the whole point of a supercharger and its Critical Altitude quotation would mean that in this case, the 66 Hg would be retained up to 19200 ft. As it doesn´t make any sense, for the moment I´ll ignore critical altitude and concentrate on the curve shapes.

For now, here´s a screenshot showing the real aircraft´s performance in dark grey, and the model´s performance in red, the 449 mph bulge of which I´m planning to whittle down at 422 mph. Let´s see how that goes!

More later...
Cheers,
Aleratorylamp

[aleatorylamp]

Hello Folks,

Once approved by the warbirds library, the Grumman Tigercat F7F3
will be available at the following link:

http://www.sim-outhouse.com/sohforum...id=19&id=27029

I hope you enjoy the aircraft.
Let me know if anything is amiss!

Cheers,
Aleatorylamp

[aleatorylamp]

Hello all,
Difficult, to convert a two-sped blower into a 1-speed one.
Here´s another result, after a few more tries. This time there´s a green line.

As propeller pitches and aircraft speeds often coincide for different points on the
graph, adjustments apply to all those places, making it impossible to act on them
separately then.

The excesive speed around 15000 ft has now gone down considerably, from 449 mph
to 431 mph, and altitude performance has improved from 344 mph to 378 mph, so that
is better now. S.L. performance is now about 5 mph high, but that´s OK.

There are two areas, around 2000-8000 ft and 18000-26000 ft, where speeds are now
5-8 mph slow. If one were to push the whole graph to the right by 10 mph, these slow
areas would disappear, but the 15000 ft peak would grow a bit again.

Thinking it would be useful to try pushing the graph to the right by 5 mph, to improve
the two slow areas, I tried simply dropping Zero Lift Drag a little, but it didn´t help
much: At 15000 ft there was a 5 mph increase, but lower down and higher up the
difference was only 1 or 2 mph - not enough, so I´ll have to try something else.

I wonder if anyone were to have a preference between the red and green graphs,
for the moment?

BTW, the 325 mph at the bottom of the graph should read 375 mph... obviously...
Cheers,
Aleatorylamp

[aleatorylamp]

Hello Folks,
No further improvements achieved on the engines and propellers,
but at least they are closer to reality than what they were before
I got the red graph, and I did want something a little more accurate.

Anyway, I´m leaving it at the green graph, and will start building
with no further delay!
Cheers,
Aleatorylamp

[aleatorylamp]

Hello all,
I´ve been busy putting together a more or less presentable and colourful
WIP model, to see how the basic shapes come through, and to test the FD.
Perhaps some of you will be interested to see how the model progresses.

Wing and tail surfaces are simple 2D planar panels, without flaps yet.
Fuselage, engine nacelles and wheels are 3D structures.
The model is as yet untextured except for the wheels, but propellers and landing
gear are animated, which adds a little ambience.
The cabin is transparent, but still being "dome" structure, its vertices don´t align
with aft-cabin fuselage vetices.

On the .air file, there has been a small improvement, although it is as yet provisional.
It has changed a bit, as some adjustments were necessary on the wing angle of incidence,
because the airplane wouldn´t do any loops. These changes affected Drag and Pitch, which
in turn influenced the whole performance curve.

So, performance has changed slightly: At altitude, contrary to what it was before, the model
is a little faster than the real plane, and lower down, very slightly lower, but the mid-altitude
peak has not changed very much.
BTW, elevator response is quite a bit too sensitive - I´ll tone it down for the next attachment.

For the moment, as the real Tigercat WEP could be used for 10-minutes, and CFS1 limits it to 5,
I have not implemented any F10-WEP. The full 66 Hg are contained in the normal throttle-lever travel.

The panel is aliased to the P51D Mustang, and sound is aliased to the P47D Thunderbolt.

So, here´s a WIP model in the attachment, for those interested to enjoy!
Cheers,

[aleatorylamp]

Hello All,
It´s coming a long a little further now, and there´s room for experimentation with different shapes.

A 12-sided fuselage cross section seemed to be a good initial choice, as it made for a nice nose and aft-fuselage shapes, but it made the top part of the cabin area look very pointed. The canopy-glass component made to match ended up too pointed as well.

The previous dome cross-section for the canopy-glass had looked much better, so it was worth trying a top-only dome structure combined with a 12-sided circle bottom-only structure for the aft fuselage.

The cabin component was correspondingly altered to match the fuselage dome-shape, and looked great for the aft-cabin area.
Not so for the tail-fuselage though: At the tailplane leading edge and fin-base it made the top part too thick. IN reality, a tear-drop shape is needed here.

Thus, only the bottom-only fuselage structure is OK here. For the top, it´s a pity one can´t combine the dome and the 12-sided circle shapes, so the fuselage-top will have to be made as a component - or maybe even two, because of because of the rather concave back...

Anyway, that will be the next step. Here are two screenshots of the shape experiments so far.

Tailplanes are 3D components now, with separately moving elevators, and the fin is a triangular top-only structure.
The rudder (also moving) has a top-only triangle cross-section for the upper structure, and a rectangular cross-section for the lower one.
Then there is a keystone cross-section structure as fixed rudder-base.

The round engine nacelles come though much nicer 12-sided instead of the 10-sided as they are now, but that will be very parts-hungry, so they will most probably end up as components later on. Note that the nacelles really do not bulge above the wing - that is only the effect of having provisional 2D planar wings!

More to come!
Cheers,
Aleatorylamp