Fabric ailerons, why ?

[NARSES2]

When aircraft had metal wings why did a lot still have fabric ailerons ? No idea why this thought came to me in the coffee shop this morning 

[rickshaw]

They were lightweight and they were cheap, Chris.  As speeds increased, they were replaced with metal facings, 'cause the air was forced through the weave of the fabric and they become less effective.

[jcf]

Not just ailerons, elevators and rudders as well, as Brian said lightweight and cheap to manufacture, and,
perhaps more importantly, quick and easy to repair and balance.

[NARSES2]

Cheers lads  Simple as that

[Logan Hartke]

In addition to what rickshaw and jcf said, early aviation manufacturers also sometimes had vibration issues with the moving control surfaces when they made them out of metal. Given their small size and the fact that they weren't structural, strength wasn't a major concern, so metal wasn't necessary.

Cheers,

Logan

[PR19_Kit]

Expanding on Logan's vibration explanation, I've read somewhere that early metal control surfaces had natural frequencies around the same as other airframe induced frequencies. Making them of fabric etc. made them weigh less and changed their natural frequency.

There was a US fighter in the 30s that had this problem and the change to fabric sorted it.

What I don't understand is why they found it possible to go to all-metal control surfaces without any issues later in the war.

[kitnut617]

I've read somewhere, that as aircraft started to fly faster than 400 mph, and what was called 'compressibility' was encountered, it distorted the cloth. IIRC, the cloth actually bulged outward causing all sorts of airflow problems. Going to metal solved some of the problem but then as the speeds started to approach 500 mph, other problems arose

[Weaver]

What I don't understand is why they found it possible to go to all-metal control surfaces without any issues later in the war.

All-metal surfaces still had issues, it was just that with the option of fabric not available, they had no choice but to tackle them, rather than avoiding them. The A-4 Skyhawk's single-surface rudder was a quick'n'dirty solution to a problem with skin 'buzz' on the original conventional item. They just never got around to fixing it...

[jcf]

There was a US fighter in the 30s that had this problem and the change to fabric sorted it.

Are you perhaps thinking of the Curtiss BF2C-1? The problem with that was the metal structure
of the new NACA 2212 airfoil wings had a resonance issue, the Hawk III export version retained
the original Hawk type wood structure and Clark Y airfoil and didn't have the problem.
Both types of wing were fabric covered.

[PR19_Kit]

There was a US fighter in the 30s that had this problem and the change to fabric sorted it.

Are you perhaps thinking of the Curtiss BF2C-1? The problem with that was the metal structure
of the new NACA 2212 airfoil wings had a resonance issue, the Hawk III export version retained
the original Hawk type wood structure and Clark Y airfoil and didn't have the problem.
Both types of wing were fabric covered.

Yes, JCF, that's the one, thanks. 

The resonance thing stuck in my mind as it's one of the fields I worked in.

I can't tell those 30s period US bi-planes from one another, there being so many of them. 

[jcf]

I can't tell those 30s period US bi-planes from one another, there being so many of them. 

Funny that until Grumman became involved with the USN, the fighters were all variations on a theme by Boeing and Curtiss. 

Army Hawk family tree, Navy Hawk tree very similar and the same type of chart could be done for the Boeing aircraft:

[NARSES2]

Love that type of family tree 

What always hits me when I look at my various books on US fighters and bombers is how small some of the production runs were back then. I suppose hand building lends it'self to small numbers ?

[Old Wombat]

So do small budgets.

[NARSES2]

So do small budgets.

True