A6M Zero Wing Thickness

[danishpasty]

Hi all, my first post on here. I am drawing up plans to build a 1/4 RC model of an A6M3 and need details on the thickness taper of the wings (as viewed from the front, not from above).
I have a drawing which shows the thickness at 500mm out from the centre line of the fuselage to be 14.4%, increasing to 15% at the centreline of the 20mm canon and then decreasing down to 9% out towards the tip. i.e the thickness does not taper constantly from root to tip.
What I need to know is if the the change in taper is on both the upper and lower wing surfaces or is the lower wing surface a straight line from root to tip and the upper surface "kinked". I hope you can understand my desciption.
Many thanks, Rob.

 

[Shinpachi]

Hello, Rob.
Welcome to the forum!

Sorry if this may look too much detailed but it tells everything about the A6M's wing shape.

The first attached image shows the section drawings with sizes of rib nos. 1, 12, 21 and 26 of the A6M2.
These are key ribs to decide the total wing shape.

The pdf file attached in the last is my perfect analysis about all ribs in the size of mili-meters.
I believe the first image will be enough to grasp how the thickness and the chord angle change.

The second image shows how the chord angle changes for your quick references.

Wish above may help.

View attachment A6M2_Wing_Rib_Data_by_Shinpachi.pdf

 

[danishpasty]

Hi Shinpachi. Thanks for all the help. In the first drawing there are 2 lines running through the aerofoil, one horizontally and one at an angle though the chord line. Can you tell me the meaning of the Japanese characters on these 2 lines and explain the distance between them, i.e. 23.62mm on rib 1, 18.5mm on rib 2 etc. I have a copy of a drawing sent from Jiro Horikoshi to Bob Diemart explaining the wing geometry but it is unclear on this issue of the thickness taper and whether it occurs on only the upper surface or on both the upper and lower. PM me with your e-mail and I will send you it.
Thanks, Rob

 

[Shinpachi]

You are welcome, Rob!

Things are not so difficult.

The horizontal one of the two lines is, as you guess, the center line which is common for all ribs.
The other is the chord. Each value of vertical direction indicates the thickness.
Yes, it is the distance from the center line.

As expressed in my pdf file,
I used 'y' for the thickness value. Plus value means the upper side and the minus does the lower of the center line.
Value for 'x' indicates the rib distance from the center of the fuselage when 'z' indicateds the rib length.

I recommend you to draw the airfoil based on those 'y' values.
My uploaded images last time may look small but you will know how large they are once you downloaded them.
Take time for scrutiny.

 

[danishpasty]

All this information is so helpfull, thankyou so much.
I will use the table of figures to put into my aerofoil programme to produce wing rib templates for cutting with cut outs for spars and lightening holes etc before cutting them from 3mm balsa wood and plywood.
Do have, or can you point me to a similar table of figures for producing accurate fuselage formers.
I have just spent the last couple of hours looking through your CGI creations. Beautifull stuff, you are truly an artist.
All the best, Rob.

 

[Shinpachi]

Thanks, Rob, for your kind attention to my CGI work but I have no such numerical data about the fuselage yet.
I have no plan either. Sorry.

 

[Ivan1GFP]

I forget what the actual percentages are for wing thickness, but I believe I have it in a reference from a report published when a captured A6M2 was evaluated. Note also there is (I believe 2 degrees) washout from root to tip. As for Fuselage Dimensions, they can be found in the Aero Detail book on the A6M Zero. I have some scans and will post when I get a chance.

- Ivan.

 

[evangilder]

I have quite a few photos of the three different Zeros I have seen fly (A6M3 and A6M5). I do get down to Camarillo fairly often and can grab a photo or 2 for you when I go there next if there is something you want to see. Keep in mind that I most likely won't be able to get inside the structure as it is intact and flyable. I may have some older photos of the old CAF Zero "Fugu" that show inside the fuselage. I will take a look and see.

 

[Shinpachi]

I think Rob is looking for CAD data but it takes a lot of time to edit.
In case of the wing, it took one month for me to calculate all coordinates by the rib.
It was a nightmare.

Sorry again but here are some accurate drawings of the A6M2 fuselage section as key ribs wishing them any help.
The number 0 firewall of A6M2 was slided to number 1 for A6M3 and later model.

 

[Shinpachi]

This is the side/upper/lower view of fuelage.
Thanks.

 

[Shinpachi]

This is the washout of A6Ms.

 

[Ivan1GFP]

The attached image isn't particularly good quality, but it gives you an idea what the dimensions are. It is from the Aero Detail Number 7 book on the A6M. Let me know if you need either a front or a top view or information on other versions.

- Ivan.

 

[Ivan1GFP]

From the Incomplete Guide to Airfoil Usage:

15% Root Thickness
9% Tip Thickness

That seems to me to be about right.

- Ivan.

 

[danishpasty]

Sorry I havn't replied to all you posts sooner and a big thankyou for all the help you have been posting. As Shinpachi says, ideally I am looking for CAD data, a table of offsets or drawings of fuselage cross sections at as many cross sections as possible. I have several good 3-views, the best being those from Maru Mechanic by Yukio Suzuki or the Design with precision series by Matsuba Minoru. I initially started working from the Aerodetail drawings by Shigeru Nohara but found them to be full of errors and the best 3 view in the world cannot tell you what the cross sections are. I also have in my collection the book of redrawings of blueprints from which Shinpachi has posted a couple of pages and even with these the size of the firewall does not correspond to the firewall on the A6M5 at the Imperial War Museum in London or the A6M3 at Duxford, both of which I have personally measured.
Merry Christmass to you all, Rob

 

[evangilder]

One thing to keep in mind is that the Zeros appear to have been hand made. There are currently 2 flyable Zeros in Camarillo that were recovered from Babo Island and while they are both A6M3s, there are some differences. The "Camarillo Zero" has screws to hold the prop spinner on, while the sister ship has rivets. Also, the 18 screws that hold the prop spinner on are not equally lined up, so you have to keep shifting until they do. There do appear to have differences between each airplane.

Some of the differences could be because of different restoration houses, but there also are some dimensions that differ slightly between them. There were 2 companies that made the Zero as well (Nakajima and Mistubishi), so there are differences there as well.

 

[Shinpachi]

Dimensions of No.7 rib of A6M2.
A trial analysis by Shinpachi.

X-Y values: Sample

<?xml version="1.0" encoding="UTF-8"?>
<shade>

<hot_spot>
<hot_spot vec3="505 0 445" />
</hot_spot>
<keyframes>
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<polygon_mesh>
<common_shape_info>
<flags fip_face="0" not_modifiable="0" not_browsable="0" hidden="0" rendering="1" />
<solid int="-1" />
<render int="-1" />
<rough int="-1" />
<unknown int="-1" />
<unknown int="-1" />
<unknown int="-1" />
<unknown int="-1" />
</common_shape_info>
<vertices>
<vertex>
<position vec3="3233.46 -2079.28 -4.81805e-012" />
<flags active="0" />
</vertex>
<vertex>
<position vec3="2795.62 -2388.27 -5.44045e-012" />
<flags active="0" />
</vertex>
<vertex>
<position vec3="2331.07 -2618.85 -5.90395e-012" />
<flags active="0" />
</vertex>
<vertex>
<position vec3="1859.8 -2784.41 -6.23574e-012" />
<flags active="0" />
</vertex>
<vertex>
<position vec3="1401.81 -2898.29 -6.46303e-012" />
<flags active="0" />
</vertex>
<vertex>
<position vec3="977.104 -2973.86 -6.61301e-012" />
<flags active="0" />
</vertex>
<vertex>
<position vec3="603.557 -3024.05 -6.71194e-012" />
<flags active="0" />
</vertex>
<vertex>
<position vec3="262.346 -3052.37 -6.76684e-012" />
<flags active="0" />


...........................................................

All values are contained in the text file "No_7_Data.txt" zipped and attached.
If unreadable, I may try it in dxf format or lwo etc.

View attachment No_7_Data.zip

 

[danishpasty]

I have measured the rear face of the cockpit section in the Imperial War museum in London and got the following dimensions:
Height 1180mm
Width across wing fillets 1036mm
Width of widest point of fuselage (your 984mm) 962mm
Distance of widest point bellow top of fuse ( your 637 ) approx. 620mm

Widest point of firewall 1094mm on A6M5.

Cheers, Rob.

 

[Shinpachi]

Thank you very much, Rob, for your measurements information of the A6M5.
They are so valuable because you measured them by yourself and, sorry, I did not know you are so serious about your RC project.
Take my apology.

As Eric pointed out in his post #15 with detailed examples, I knew there were measurement differences of A6Ms by the maker or
the model but, this time, those differences between Rob's and mine are more than my expectation.

My measurement was based on a photo taken during the war and I obtained it from a reliable source in larger size.

I have trially checked each difference ratio to compare.
The bigger was mine.

Vertical ratio:
1.0288983050847457627118644067797 for the height
1.0274193548387096774193548387097 for the center line from top
Average 1.028158829961727720065609622744

Horizontal ratio:
1.017471042471042471042471042471 for the fillets distance
1.022869022869022869022869022869 for the widest of fuselage
Average 1.02017003267003267003267003267

To my wonder, the vertical ratio is bigger.
It is longer 1.0078308488152572251726667272541 times than the horizontal.

I have asked one of my friends who also studys the A6Ms for a long time.
"I can't tell, my friend, the exact width as I don't know but the height of No.7 was 1180mm."

The photo might have been distorted longer or shorter though I believe it was an original print

I do appreciate, Rob, for you precious information.

 

[Shinpachi]

A newly manufactured frame No.7 in my imagination
Thanks!

 

[wells]

Shinpachi,

What is the source of the first image in post#2? Thx