A6M2b type 21: about aileron trim tabs and mass-balances ?

[le_steph40]

Hello,
I'll begin new builds: 2 A6M2b type 21s of Tainan Kokutai (S. Sakai and T. Ota) but I noticed some details regarding mass-balances and trim tabs. If I well understood what I read in my docs, it seems these 2 modifications were deleted from the 326th aircraft (mass-balances not really deleted but "hided" in the internal structure of the aileron).
So, if I want to build A6M2b type 21s of mid-production=> no trim tab and no mass-balances... Am I right ?

TIA, regards.
Stéph.

PS: the model kits are Hasegawa (both) and the assembly instructions indicate to fill trim tabs but to put the mass-balances...

 

[Crimea_River]

I expect Shinpachi or Wayne Little might be able to answer that. I certainly can't.

 

[Wurger]

It looks like... These external mass balance plates were introduced with the A6M1. According to my info, the trim tabs were added with the aircraft no.3127 just because of the troubles with structural vibrations and Lt. Yasushi Nikada's crash in April 1941 when his A6M2 Model 21 (serial 1140) lost both ailerons while diving. Because the problems with the structural strength of wings still weren't sorted out , the thickness of the wing skin was increased and added some reinforcement. Additionally the external mass balances of ailerons returned instead of the trim tabs. The modernized plane was called A6M2b Model 2 Ib The external mass balances were retrofitted to earlier made Zeros and named A6M2a Model 2 Ia. The trim tabs were used for 80 A6M2 Model 21 only that were made in February-May 1941 period. In the mid of September 1941 the new aileron with the internal mass balance attached in the front section was used. And this allowed to remove all the external masses. The change was introduced with the Zero no.327. So if your kite is the no. 327 or later you should have the ailerons without the trim tab and the external mass balance plates.

Anyway it seems that if no trim tab there is the plate of the mass balance riveted. But if no plate there is the trim tab.

external mass balance ... no trim tab

the A6M2 model 21 tested in the USA ... also can't see the trim tab actuator on the undersides.

 

[Wurger]

Contrary to these above here is the Zero with the trim tab ... the actuator of the trim tab can be noticed.

and there is the A6M2 Zero preserved in the National Museum of the US Air Force.

the pic source: Mitsubishi A6M2 Zero (Zeke) Photo Walk Around

 

[MIflyer]

On the A6M3 the aileron trim tabs were ground adjustable only.

 

[le_steph40]

Wojtek,

If I well understood my docs, it seems the trim tabs were mounted from the 127th but were deleted shortly after.

 

[Wurger]

Yes, that's correct. Just the Zero serial " 3127 " seems to be the same that the "127". It looks like the 3127 can be its full number. The digit "3" may mean the factory the A6M2 was assembled by. Then they mounted the trim tabs for 80 planes only. The Mitsubishi engineers suggested leaving the trim tabs but the IJN ordered removing them because of being not sure what was the reason for the crash of the Cpt. Shimokawa , test pilot who was killed during trials on 17th April 1941. Begining the May 1941 the external mass blance was restored and attaching untill the September 1941 when the aileron with the internal mass balnce was introduced.

 

[le_steph40]

Yes, that's correct. Just the Zero serial " 3127 " seems to be the same that the "127". It looks like the 3127 can be its full number. The digit "3" may means the factory the A6M2 was assembled by. Then they mounted the trim tabs for 80 planes only. The Mitsubishi engineers suggested leaving the trim tabs but the IJN ordered removing them because of being not sure what was the reason for the crash of the Cpt. Shimokawa , test pilot who was killed during trials on 17th April 1941. Begining the May 1941 the external mass blance was restored and attaching untill the September 1941 when the aileron with the internal mass balnce was introduced.

It's I found in my docs , so, I think no trim tabs and no mass-balances for my two builds belonging to the 2nd Chutai. It's probable that the Zeros of Tainan Kokutai were, for most of them, news (apart thoses included in the 4th Chutai arising from the former 4th Kokutai).

 

[Wurger]

Sounds good.