Jump to content

Recommended Posts

Hello Bedders and thank you for your reply. I was convicted too that the slim blister ( Monforton call it the "reinforcement blister bar" being actually a solid streamlined piece of aluminum(?) reinforcing the roof of the wheel bay) was there in war time but there is evidence that it is a post-war addendum. The best evidence I have is a photograph (IWM iirc) showing airmen refuelling RM764 and the blister is not there. Monforton shows that this part is used to reinforce the wing former in the wheel bay when this is cut to make room for a bigger wheel or for a different wheel toe-in and in fact it often appears in E-wings having the big wheel blister too (see above, Eduard late E-wing topside). If I remember correctly (I do not have my PC now) belgian air force museum SG-57 has the blister even if neither the former is cut down  nor the big blister is present. I think the blister was added later in the life of the aircraft as a strenghtening measure for the wing skin. But no photograph that I m aware of shows this blister on a war time high-back Mk.XIVe. I have tried to use at best the few documents I have access to, but I could be totally wrong on this point.

Thank you, 

Stefano

PS tomorrow I will try and publish the reference photographs I m talking about!

Link to post
Share on other sites

Hello!

having access to my PC now, I've checked again the matter of the reinforcement blister bar on the wheel well ribs.

First of all, here the photographs showing RM764

spacer.png

It clearly shows no blister at all on the wing surface (except the cannon one)

After Bedders contribution showing that the Belgian Mk.XIV have the reinforcement blister bar on the inner wheel well rib, I double checked with the photographs available on line and -yes Bedders you're perfectly right! It is not on the outer rib like in the modification big blister+small blister, it is on the inner one.

Someone posted a walkaround of RM921/SG-57 at Florennes museum, and here I re-post a picture of the right-hand wheel well:

spacer.png

It is well evident in the photograph that the innermost rib was cut down (the U-shape is interrupted to make place for the tyre, the rigidity of the rib is restored by rivetting the cut-down part of the rib to the blister bar on the upper wing skin surface-the late acting as a bridge between the U-shaped remaining parts). Why this was done on the belgian Spitfires? Cross-checking with pictures in Spitfire Engineered book, it is evident that even the outermost rib has been modified to allow more room for the wheel/tyre, but it still mantains an acceptable stiffness. Here a poor scan in which I circled the modified areas

spacer.png

I think that the Belgian Spitfires were equipped with larger-section tyres on customer's demand, and thus required the ribs modification and fitting of the reinforcement blister bar on the innermost rib position. What is your opinion?

Thanks for looking

Stefano

  • Like 4
Link to post
Share on other sites

AFAIK its a rather common post-war mod to allow for the axle changes on the wheels due to the increased use of hard runways.

Also done on IX/XVI's and other marks, and followed later by the wheel well bulges. 

  • Like 1
Link to post
Share on other sites

Intersting. I remember the point about geometry changing on IXs and XVIs to enable better use of paved runways, which necessitated the bigger bulge and outboard rib blister being introduced. Perhaps on the XIVs they found that just the inboard rib bluster would suffice. But I hadn't noticed that they weren't present on early XIVs: every day is a school day...

 

Justin

Link to post
Share on other sites

Hello thanks for the answers; I never noticed this kind of modification (just the small blister) on other Marks, but actually I never look for it! The first time I noticed this setup is looking at BAF Spit Mk XIV.

On spitfiresite.com I read that the big blister and consequent small blister mods are related to a difference in wheels toe-in when operating from paved runways (the early Marks having toe-in, and that being zeroed later), but I'm not convicted. Monforton shows that the standard landing gear geometry produces no toe-in; if both he and spitfiresite are right, this would mean that the landing gear was later modified for having toe-out (which I believe is an unstable setup)... now undestanding the modification applied to BAF a/cs (more room for the wheels toward the front of the wheel bay) makes me think that both this kind of modification and even more the later "big blister" one are predispositions for using thicker wheels (the big blister being able to host the three-spokes wheels used later on the Mk XVI) for operation on tarmac.

 

  • Like 1
Link to post
Share on other sites
On 08/01/2021 at 21:48, Bedders said:

You're doing what I and probably many other 1/72 Spitfire appassionati have considered, but not dared to start for fear of destroying an excellent Eduard kit and an increasingly hard-to-find Airfix 22.

A very interesting WIP. I can only agree with @Bedders that you display excellent skill in cross-kiting and modifications and I have to admit that I have to refrain form doing the same with these models, which I got in my stash, since I lack such outstanding craftsmanship. 

 

Are you planning to use the rest of the Airfix Mk 22 donor kit for a similar future project that involves a Griffon Spitfire? Maybe a cross-kitting with an AZ highback Griffon fuselage to create a more accurate Mk 21?  

Edited by 112 Squadron
Link to post
Share on other sites

Hello 112squadron, thanks for the flattering comments, I'd really like to have such outstanding craftmanship! 😀

If I ever try again a Griffon conversion, I'll go for a Mk.XII. I think that it is one of the most difficult Marks to get right and I love challenges. My next Spitfire could be a plain F.Mk.XI (if I'm wise enough) or a PR Mk. XI (if masochism prevails) based on Eduard. I really hope that Eduard releases Mk.I/II/V in the meantime. 

Thanks, Stefano 

Link to post
Share on other sites
On 08/01/2021 at 17:07, steh2o said:

The other major fuselage work is the adjustment of the vertical fin to the broader and higher Mk.XIV configuration. This was done by transplanting the relevant portion of a Sword Mk.XIV fuselage (I had it, why not using it?) and some reshaping to adapt it to the Eduard fuselage. A scaled 2,75" fin extention was added (in white styrene).
Please note that in Jun Tenma drawings this extention is not represented resulting in a wrong fin/rudder profile. The drawing has been adjusted considering this extension and the rudder shape deduced by factory drawing and photographs.

spacer.png

 

In the following photograph you can see a comparison between a Mk.VIII and the Mk.XIV fin/rudder: overall the Mk.VIII is slightly taller here than the Mk XIV is.

spacer.png

 

the XIV fin and rudders catch out a lot of people.   

"

There is some confusion with the rudders fitted to the Mk.14 and 18 Spitfires. I find that the Morgan/Shacklady "bible" is often less than helpful and sometimes irritating. As Edgar mentioned in a previous post (on contra props) the 14/18 fin/rudders areas are given as the same. This is not so and this "red herring"is the cause of some confusion. The 14 fin went through a considerable change in area and the only real reference given in the"bible" is a sketch showing an interim straight leading edge modification and it omits to mention that the height at the rudder post was increased by almost 3". The standard rudder post height of all the earlier Spits was 58".

The extra 2.75" fin height increase was achieved by fitting a "block false tip". The Mk.18 had a broader chord rudder and a deeper horn balance. This rudder was also fitted to other Mk.14 based airframes,( by the simple expedient of "removing the block") such as FR14e, 19, and the Mk.21 when fitted with a contra prop.

This illustration I have cobbled up might help. It is the tail of an FR.14e and I have superimposed the outlines of the Mk.14 and Mk.18 rudders on to it, the white area is the "block" . The blue outline is the 14 and the red 18.

The join line (lower edge of the block) seldom shows up on photos and is often shown as a panel line in drawings but too low down, a mistake repeated on my own Mk.21 conversion as this was made originally to the Cook drawings.

File1257.jpg

John"

 

I really like they chipped to brass on the leading edges of the prop blades,  an often missed detail.

It should be noted the Airfix prop is slightly too small for the 22/24, but good for the XIV, as these have smaller diameter propellers,  IIRC 22/24 = 11 feet, XIV = 10 ft, 5 inch.

 

I'll add in a @gingerbob regarding the wheel upper wing bulges, I think the XIV is different to the IX/XVI, and did not get the teardrop bulges retro fitted. 

If I find the discussion, I'll add in the link.   Apologies if you have found this all already.

  • Like 4
Link to post
Share on other sites
5 hours ago, steh2o said:

If I ever try again a Griffon conversion, I'll go for a Mk.XII. I think that it is one of the most difficult Marks to get right and I love challenges.

You do basically what you have done here, but cut more off the back of the Griffon nose,  the front section of the nose is basically the same on all the Griffon Spitfires. 

 

Add the magneto bulges, and 4 blade prop to an Eduard Mk.VIII and that basically it.  I'd say it was easier...

 

The two stage Griffons are are longer at the rear of the engine, so the difference is between the firewall and the rear of the engine block. 

41sqdn-spit12.jpg

 

Spitfire-FRXIV-RAF-MV247-fuel-functionin

 

 

I have measurements of a Seafire 17 cowling somewhere that the owner of one was kind enough to make for me, as I don't know if there are decent plans available, the Peter Cooke drawings get the cowl panel length slightly wrong.  

  • Like 2
Link to post
Share on other sites

I came across this picture that nicely illustrates the difference between the mk18 style rudder and the normal 14 on Belgian mk 14's

 

the mk18 rudder had a typical Z shaped trim tab

 

https://www.belgian-wings.be/supermarine-spitfire-fr-14-part-2/sg-75

 

i also remembered airfix has both style rudders in their xiv kit (perhaps they'll do a Belgian version at some point since they like to bring out different decal options) so i dove into the stash. as mentioned before the rudder post will have to be trimmed to accept the larger variant

 

IMG_20210120_084728

 

 

finally here are some random detail shots i took of a mk 14 (with the mk18 rudder) in the aircraft hall of the Belgian army museum
 

 

https://www.flickr.com/gp/169017954@N05/649693

 

it's worth mentioning this plan was restored in the 80's. it was transferred the the museum after a crash in 1948, all this to say some component might not be as they where on the original or on a wartime spit.
 

 

Edited by lunarhighway
additional info
  • Like 2
  • Thanks 1
Link to post
Share on other sites

Hello Cookenbacher, Troy and Lunarhighway, thank you for your contributions and comments.

Sincerely I feel in awe showing my work on a Spitfire here... I did my best to collect the right info before starting the conversion work but even today I discover new particulars and issues about it that I totally misunderstood at the beginning.

Regarding the rudder I started from the photograph that you have attached above, and the discussion that Troy cited above

. As a reference I used the period photographs plus preserved a/cs photographs. I added the infamous 2.75" "block false tip" to the Mk.XI fin (it should be 0.97mm high in 1/72), then modified the Mk.VIII broad chord rudder to match the shape of the photographs. The balance horn should have an height of about 8-8.5" (this is in disagreement with the post of john@aeroclub september 23, 2015, but this post is in disagreement with the previous ones in the discussion too, claiming that the rudder post of the Mk.XIV increased by just 2", from 57.52" to 59.5" so a <2" block false tip). The 2.75" block false tip and 8" balance horn seem to agree with photographs.

 

Troy, I'd like to better undestand some particular about the Mk.XII matter:

-the Mk.XII cowling profile seems very close to the Mk.XIV and later Marks; am I right to suspect that the lower cowling panel has a different shape? I ask that reasoning that it has to accomodate the same heigth difference between spinner and lower wing in a shorter space. The upper panel should be just shorter at the back?

-I have to add the magneto bulge, while the cylinder heads bulge are slightly shorter am I right?

-Is the spinner basically the same of the Mk XIV or is it shorter?

-Is the propeller exactly the same as in Mk VIII?

TIA

 

Lunarhighway,

thank you for the photographs!

 

 

  • Like 2
Link to post
Share on other sites
4 hours ago, steh2o said:

Troy, I'd like to better undestand some particular about the Mk.XII matter:

-the Mk.XII cowling profile seems very close to the Mk.XIV and later Marks; am I right to suspect that the lower cowling panel has a different shape? I ask that reasoning that it has to accomodate the same heigth difference between spinner and lower wing in a shorter space.

AFAIK, no, note how the lower wing to lower cowling is basically flat.  For the sake of clarity, I'll use arabic numerals. (12 not XII) 

 

 

Note the Seafire 15 and 17 use the same single stage Griffon, so they have the same engine installation, so the same cowling,  though they lack magneto between the cylinder banks which is the reason for the teardrop bulge between the cylinder bulges

Spitfire_MkXII21_zps088363ce.jpg

 

GJ-Seafire-009.JPG

from

https://www.britmodeller.com/forums/index.php?/topic/74606-supermarine-seafire/

 

 

Quote

The upper panel should be just shorter at the back?

yes, see in flight pic

Quote

-I have to add the magneto bulge, while the cylinder heads bulge are slightly shorter am I right?

No, the main engine block part of the Griffon, is the same,  so the cylinder head bulge is the same. 

 

the early Griffon is are single stage, for low level use,  which is why the XII, and Seafire 15/17 use them, the Griffon 60 series engines are two stage supercharged for high level use, as such the engine installation and cowlings on the Spitfire 14/18/19/21/24/24 are basically the same.

 

The single vs two stage parts are at the back of the main engine block,  the two stage is longer, and this makes the nose longer, but all the length is between the firewall, and the back of the engine block.

 

THis is a pdf of various Griffon's showing what I mean

http://www.wwiiaircraftperformance.org/Aircraft_Engines_of_the_World_Rolls-Royce_Griffon.pdf

 

 

 

I Think this is a two stage Griffon, note all the parts at the back

Rolls-Royce-Griffon.jpg

 

Thus the front part of ANY Griffon Spitfire/Seafire basically the same.    

 

 

 

After much searching, ironically in a thread here 

Seafire 1515-PR50327May2010week190014aJimCoop.jpg

Spitfire 19 and this shows the extra length between firewall and back of engine block 

maxresdefault.jpg

 

Seafire 17 cutaway

seafire15-1.gif

 

 

Spitfire 21

Supermarine-Spitfire-Cutaway.jpg

 

Quote

-Is the spinner basically the same of the Mk XIV or is it shorter?

AFAIK, yes, the same basic shape and length, but 4 blades.

Quote

-Is the propeller exactly the same as in Mk VIII?

No, the Spitfire VIII, or any Merlin prop, is different, as the Griffon rotates the other way.  

 

If you are OK with chopping up kits, AFAIK the Sword Seafire 15 is OK, and would give the nose and prop, but other will know more.

 

read for more,  I hope this makes sense....

 

  • Like 2
  • Thanks 2
Link to post
Share on other sites

Troy

thank you for the wealth of information!

I must think about it! I'll take some time to undestand well the critical points of this conversion... I completely forgot that the Griffon an Merlin require oppositely-handed propeller blades, for an example!

Thank you!

Stefano

  • Thanks 1
Link to post
Share on other sites

Oh no .....

Troy wrote about the Mk XIV fin/rudder argument; yesterday I checked photographs and a drawing that Gingerbob provided to Airscale when building his beautiful Spit Race #80, see page 10

To sum up: my fin/rudder combo needs some adjustement; and Jumpei Tenma's drawings are (probably) right.

The error (or a misunderstanding by my part) is in the extension of the fin from the standard (MkVIII let's say) configuration to the F.Mk XIV configuration:

this is NOT 2,75" as affirmed elsewhere but 4,5", repeat the fin is 4.5" higher; I believe that the 2,75" measurement comes from a constructive feature of the fin, that is: the skin of the fin is extended in height (with respect to the Mk.VIII) 1,75" overlapping the "block false tip" and rivetted to it, leaving just 2,75" of the extension showing. From the outside, it seems like there is an extension of just 2,75" (see photographs in the Airscale post) while being more in reality.

I need to disassemble the  rudder and adjust fin height  and rudder horn height (that being 6,59" in my Mk XIV).

I will post the calculations in the post about Mk XIV rudders too, here below I paste again the drawing of the rudder

spacer.png

Edited by steh2o
  • Like 2
Link to post
Share on other sites
On 1/20/2021 at 12:55 PM, Troy Smith said:

...Add the magneto bulges, and 4 blade prop to an Eduard Mk.VIII and that basically it.  I'd say it was easier...

Sorry if I've missed reference to it elsewhere, but there might be another consideration - I think that the XII had the underwing oil cooler (a la Mk V) and therefore did not have the symmetrical radiators of the XV or 17...

  • Thanks 1
Link to post
Share on other sites

Hello Andrew,

thank you, yes I remember the Mk.V oil cooler thing: I plan to transplant a Tamiya or Sword oil cooler there....

I bought a Sword Seafire Mk XVII as a donor last night.... perhaps I'll start a new W.I.P.

In the meantime, I started building a new rudder for the Mk.XIVe, then I will remove the wrong one, extend the fin, repaint everything...

Link to post
Share on other sites

Hi Stefano,

 

I'm not surprised that you had considered the oil cooler for the Mk. XII - I just wanted to make sure.

 

Good luck with the re-worked rudder and I look forward to another project thread of yours!

Link to post
Share on other sites

Hi Andrew hope tomorrow to post the results of the rudder re-built. Thankfully Eduard Spits are a good source of spare parts!

 

Link to post
Share on other sites

Not much time available for modelling this weekend....

Anyway I started the work for correcting the rudder...

First of all, I checked the drawings of Jumpei Tenma and it seems like they are right! Had I believed him at the beginning...

Let's start. First, new spare broad chord rudder and a donor part fot the new rudder horn. After some check, I decided for one of the leftover tail parts

spacer.png

Razor blade for surgery....

spacer.png

...then gluing the "new" parts in an approximate position with the aid of JT plans. When the new horn is attached, you need to flood the junction with liquid glue so that it becomes robust for the next phases...

spacer.png

The next day: the horn thickness and its profile are adjusted with the aid of a rigid file (I'm using sandpaper CA-glued to an alluminum flat part, upper right-hand of pic). The sawtooth blade is used to separate the rudder trim tab, the navigation light is cut off and a hole is drilled to place instead a clear part after painting. At this point the shape of the rudder balance horn is just approximate (it has to be filed to shape when it is mounted on the fin to get a smooth, no-corner profile).

This time the dimensions, though, are right. Height overall is measured by caliper to be 24, 34mm (68,94" x 25,4 / 72=24,32) while height from bottom of the rudder to the bottom of the balance horn is measured as 22,0-22,1mm (should be 62.39" x25.4 /72 = 22,01mm)

spacer.png

Can't you see the difference? Plans, original, new...no? I can't see it until...

spacer.png

there's a nice 0,6+ gap, or 1,75" in scale, as predicted... looking at this photograph I notice that I have to adjust the position of the tailwheel doors too.

Allright, now there is a small adjustement to do that is...

spacer.png

...glue a 0,6mm fin extension and a 0,1mm shim on the fin leading edge to restore the right curvature, glue stretched sprue lengths in the original panel line to remove it, then apply CA to obliterate the rivet lines, then sand flush, then scribe new panel lines, rivets....

...and do this trying to forget that this is a painted and nearly finished model!

  • Like 8
Link to post
Share on other sites
4 hours ago, steh2o said:

...and do this trying to forget that this is a painted and nearly finished model!

I'm always impressed by folks who attempt work like this so late in the piece and then go on to make it look as though it was always thus... we all have faith in you Stefano!

Link to post
Share on other sites

January 26, 2021:

while the modification of the fin and rudder goes on (thankfully the building phase went ok and I will document it later, after painting), I want to spend a couple of words on the painting phase. The subject being in Day Fighter Scheme, I had to choose the right colors for it. I love Gunze acrylics but GS color line is a mixed bunch in term of availability of specific hues and accuracy of the same; sometimes they are great, sometimes they are not.

I painted this Spitfire trying to match the color chips of Model Art N.387 on the Supermarine Spitfire, Masking was done with the usual masking tape, slightly  raised at the borders to avoid a too stark transition between colors

spacer.png

Here a photograph at the end of the Dark green application (which at this point was a mixture of H73 and H26).

Here below, comparison of the result with the chips: I don't know what I was thinking but...

spacer.png

spacer.png

...in whatever illumination I checked it, Ocean gray resulted TOOOOO light!

So I painted again Ocean gray with a darker mixture; after that, I checked my RAF Dark green against Vallejo 893 and modified a little bit the green too!

At the end, I was satisfied  with the result (accepting that my colors are at least a good match to the real ones and are pleasing to the eyes).

The Sky  band is an easy match with the "CG" codes, because I painted them too, more of it in a later post about detail painting, markings and weathering

Edited by steh2o
  • Like 5
Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...