New Hi-Poly Spitfire in the works

[lythronax]

Hello! Having taken a break, learned some new skills in MAX, and found flaws in the basic dimensions of the model, I've elected to do the maths and very rigorously plan out the dimensions in a jig - accurate to the millimetre. This should allow better cross referencing of dimensions. Additionally, I've figured out a way of scaling plans/drawings based on the size of individual parts and panel lines according to engineering measurements as opposed to the full length/wingspan of the aircraft, as these measurements are commonly and broadly misquoted; the wingspan of Spitfires Mk 1 through Seafire 47 (excl. extended and clipped tips) is 11.25m/36'11", NOT the commonly quoted 11.23m/36'10". Similarly the length of the Spit IX with small rudder is 9.51m, NOT 9.47m. The use of these commonly and erroneously quoted measurements found in books leads to errors which exacerbate themselves dramatically as more of the aircraft is modelled.

Having brought my new, accurately scaled model into GMAX to compare with the old one, I discovered the latter to be overscaled significantly. I've therefore decideded to press ahead with the new model, this time starting with the Griffon powered variants.



As for the two-stage Griffon nose, I'm relatively happy with how the general shape and bulges have come out. The single-stage nose can be made by removing an edge loop near the base and bringing the whole front back - the forward part of the cowl is exactly the same.



I am extremely happy with the new wing however.



I'd also like to demonstrate how simple the needed change in geometry is in order to produce the later Mk 21 wing - up to station 21 (the removable wingtip) the airfoil and geometry are identical. All one needs to do is fit the wingtip to shape using a freeform modifier. The larger aileron was fitted to the shape of the Mk VI-VIII extended wingtip, but when it was decided to cut the wingspan back to 11.25m, the aileron was not reshaped to the classic planform and the extended tip was simply shortened and rounded off to the original span, thus the broader chord wingtip.


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[Bradburger]

Very nice!

And interesting to hear about the scaling issues and how you dealt with them, and the MK.21 wing shape.
I know this a CFS3 aircraft, but P3D v5 onward could do with a some top class Spitfires models!

(Flight Replicas should be releasing a very nice MK.I made from the original drawings in the not to distant future).

Cheers

Paul

[sixstrings5859]

Awesome work. Keep it up ! Love to see your fine work in progress ! Thank you ! Regards,Scott

[gecko]

Very cool! And nice to hear a Mk.XII hinted at - my favorite Griffon Spitfire!

[lythronax]

Very cool! And nice to hear a Mk.XII hinted at - my favorite Griffon Spitfire!

I've had my eyes set on it for quite some time but reference material is scarce!

[gecko]

The only thing I have is a set of Mk.XII pilots notes which might be useful for cockpit details and then some flight test data.

[lythronax]

The only thing I have is a set of Mk.XII pilots notes which might be useful for cockpit details and then some flight test data.

As far as I'm aware it's essentially a Mk Vc cockpit with the Griffon throttle quadrant, priming pump and a lever for the supercharger above the throttle; it'd be nice to find a drawing for the latter but I'm sure I could model it off photos.

I have the flight test data but until someone can work out two-speed supercharging it'll still be like a single-speed + turbocharging as per usual :/

[gecko]

I'd have to check a couple things, but there are a few more differences inside, like the ring pull to reload the Coffman starter breach. Not sure about the supercharger lever, but I do have working code that can be adapted to superchargers with two or more speeds for single engine aircraft.

[gecko]

Turns out it's a mess. Most were based on the Mk.VC, but the last 45 were Mk.VIII airframes. The Mk.VC aircraft had a manual radiator shutter control and only the fuselage tanks, while the Mk.VIII based aircraft had an automatic radiator, additional fuel tanks in the wings, and a retractable tail wheel. Somewhere along the way it seems that the supercharger lever was removed, possibly due to a change to an automatic system, but I don't have enough info to confirm the reason for the change.

[lythronax]

Turns out it's a mess. Most were based on the Mk.VC, but the last 45 were Mk.VIII airframes. The Mk.VC aircraft had a manual radiator shutter control and only the fuselage tanks, while the Mk.VIII based aircraft had an automatic radiator, additional fuel tanks in the wings, and a retractable tail wheel. Somewhere along the way it seems that the supercharger lever was removed, possibly due to a change to an automatic system, but I don't have enough info to confirm the reason for the change.

This isn't entirely true; the last 45 used the VIII tail-unit/empennage and corresponding retractable wheel, but all 100 used a proprietary Mk XII flush riveted fuselage and Mk Vc wings - so no wing tanks or short span ailerons. The pilot's notes don't mention an automatic radiator so I'll assume the manual control. Going by the pilot's notes, the other differences in the cockpit from the Vc (other than what you've mentioned) are that it uses the VIII/XIV layout of buttons and switches on a dedicated console under the trim wheels, beam approach switch, bomb switches and a fuel transfer selector cock.

As for the model, I built the armoured fuel tank cowl and gave the engine cowling some thickness at the rear;




I then began on the fillet, which will remain a separate part from the wing and fuselage, constructed much like the real thing (note also the rear-view fuselage that I built at the same time as the high-back);




And here's a quick export to CFS3;

[gecko]

The text of the pilot's notes is as you describe, but the annotated cockpit photos show an aircraft with wing fuel tanks, automatic radiator shutter and possibly automatic supercharger gear change. This doesn't fit with the first part of the pilot's notes at all. I wonder if the aircraft used for the pilot's notes pictures was the prototype Mk.XII during the time when it had the Griffon VI installed. It might explain some of the discrepancies, but not necessarily all of them.

[sixstrings5859]

Outstanding ! Nice to see this in progress. Regards, Scott

[lythronax]

The text of the pilot's notes is as you describe, but the annotated cockpit photos show an aircraft with wing fuel tanks, automatic radiator shutter and possibly automatic supercharger gear change. This doesn't fit with the first part of the pilot's notes at all. I wonder if the aircraft used for the pilot's notes pictures was the prototype Mk.XII during the time when it had the Griffon VI installed. It might explain some of the discrepancies, but not necessarily all of them.

This wouldn't surprise me! I imagine the production Mk XIIs would have had the later rounded blind flying panel too; I know for a fact the entire production run used Mk Vc wings exclusively, so why there'd be such a device in the cockpit, unless it was to do with drop tank operation, I couldn't explain.

[gecko]

Well, going with the the fact of the VC wings (which does make sense, because the single stage Griffons didn't need an intercooler between stages, allowing for the rounded oil cooler instead of symmetrical radiators found on Mk.VIII wings) we can rule out wing tanks and automatic radiator and their associated controls in the cockpit. Drop tank controls were mounted on the floor to the right of the seat, so that isn't what is shown in the pilots notes picture. The picture, then, is of a very non-standard aircraft, and it only makes sense that it would be the prototype. The publication date is November 1943, and that aircraft had the Griffon VI installed in June, so that would explain the throttle quadrant being different than described, and the presence of a supercharger ground test button, since the Griffon VI did have automatic gear changing and the III and IV installed on production aircraft did not.

The mystery then is what did the standard Mk.XII throttle quadrant look like, and what the console under the trim wheels looked like, since it wouldn't have had at least two of the controls that the Mk.VIII console had. Perhaps it was the same as the Mk.VC?

I think the rest of the cockpit would have been probably more similar to the Mk.VC cockpit.

[lythronax]

Not a whole lot new to report, just finished up the forward end of the wing fillet;

[hairyspin]

How’s it shaping up with the wing fillet underside? That’s a very characteristic area for any Spit.

[lythronax]

I feel as though I've got the shape figured out pretty well, it's more a case right now of getting all the panel lines of the lower wing skin and fillet skin in the right spots, seeing as I'm constructing the model broadly like the real thing and not stitching the whole outer mesh into one conjoined piece. The lower wing skin more or less continues to the inboardmost edges of the radiator baths and thus has the beginnings of the fillet's gull shape. Getting plans into MAX and verifying them I find massively tedious and I put it off for as long as possible.

[lythronax]

Got a fair bit done this evening - finished the fillet and made some preliminary tail units;

Here's the model with each part using an individual material to show how it's been built; none have been fully polished but it gives a good impression:




I then made the classic small tail unit of the Mks I-XIII (and XVI)...;


...which was quickly modified into the early two-stage Griffon unit (longer ribs in front of the fore spar, small block extention at the top and a fairing with the fuselage)




Here are some examples with a uniform material;

Spitfire FR XIV (rear view)



Spitfire F 21

[lythronax]

And here are some sim imports of random variants - I won't necessarily be making these ones first; looking good to my eyes so far!

Spitfire FR XIV




Spitfire F 21

[sixstrings5859]

Excited ! Coming along wonderfully ! Thank you Sir ! Regards,Scott

[lythronax]

Results of this evening's work - a completed tail unit and preliminary rudders (early i.e XII, and mid i.e XIV/21)!

[lythronax]

Much to report tonight!

First off, I cut out the rear-view panel on the high-back fuselage and gave it a glass material, followed quickly by the production of the horizontal stab' and elevator;






Next on the agenda were the F Mk 21 ailerons, their housing in the wing, the fairings for their control actuators, and early-production extended tips;




The rudder, elevators and ailerons are all rigged for correct animation in-sim;




I've a video posted here to show how the control surfaces animate in-sim at current; I would REALLY like to get the servo/balance tabs animated and working once I model them, same with the trim tabs if possible. Is this something I'll be able to achieve?

What's next?

Next I'd like to finish the ailerons; immediately thereafter finishing the rudder and elevators, and modelling the stab' fillet, are my goals. From then on I think either the canopy and a basic cockpit or details like the prop, exhaust, undercarriage, etc. will be next.

Any comments/tips would be hugely appreciated!

[lythronax]

Here's a video of the flight model I've been working on for the F Mk 21 (early);

https://youtu.be/R7IWyMfUXP0

I've endeavoured to make it appropriately heavy, though with effective controls throughout the flight envelope. The biggest advantage of the F Mk 21 & onwards were the large, tabbed ailerons with the standard tipped version having a rate of roll of about 120*/s at 300 mph IAS, and this is reflected in the FM. The typical Spitfire "feel" is present, incl. neutral static stability with the power on. I've also included roll/lateral instability as described in the pilot's notes. Speed and rate of climb match the numbers as best they can considering the stock engine model.

[hairyspin]

Animating spring-tab ailerons is easy, just align the pivots of each to match orientation of the aileron pivot in question, but pointing the opposite direction, and name each as another aileron. The sim will do the rest, pivoting the tab in the opposite direction to the aileron as you initiate roll.

[lythronax]

Lastly, here's a short video demonstrating the gun setup of four Hispano Mk II cannon with 650 rounds per gun;

https://youtu.be/Ac9gwmx26PQ

Animating spring-tab ailerons is easy, just align the pivots of each to match orientation of the aileron pivot in question, but pointing the opposite direction, and name each as another aileron. The sim will do the rest, pivoting the tab in the opposite direction to the aileron as you initiate roll.

Thank you! This is good news. Another worry off the list

I suppose I'd best clarify what my intentions are appropos order of modelling/release; I plan on doing the "Victor" marks first, namely the F Mk 21 (in 3 variants: early, mid and post-war), the F Mk 22 (in 3 variants: early, standard and export) and the F Mk 24 (in 2 variants: early and late). I'll probably do the corresponding Seafire variants too. If all goes well I'll do the earlier marks, i.e XII, XIV and XVIII, thereafter.