Elevator trimming on Central Powers types

[KiwiZac]

Prompted by a discussion in another thread, I thought this interesting subject deserved a thread of its own.

I asked Achim Engels, noted builder of full-scale reproduction Fokker aircraft, about his knowledge of elevator trim in German aircraft of the Great War and he had this to say (I have fixed some typos):

There was no such thing as elevator trim on Fokker aircraft and I do not think or have heard of elevator trim on other types. There certainly was something for bigger types which might have had more CoG movement on long flights. In general elevator trim was set on a fully loaded aircraft during acceptance flights. It was then adjusted by means of the turnbuckles to a set and fixed position. This holds true for all rudders and is not limited to elevator. If a tendency is noted to go in one direction when the acceptance flights were done, the turnbuckles were set on ailerons, rudder and elevator. No trimming was asked for in the regulation for military fighter aircraft construction. That said it was not something that was especially asked for or demanded by the military.

Noteworthy might be the eölevator damping on early Fokkers. This was a friction device attached to the control column, but Fokker got rid of it during the war. It was in use up until the E.IV

Achim has some images to share which I hope to get uploaded in the next few days.

[uncletony]

Players of Rise of Flight who fly CP know this to their chagrin. There are several allied/entente types with elevator trim, allowing one to fly hands off for a spell, but not so on the German aircraft -- at least the scouts...

[KiwiZac]

That's a game I'd quite like to get into!

More from Achim:

You can see the elevator damping device in the upper left corner of that French report
Drawing via Achim Engels 01 by Zac Yates, on Flickr

And here is the original Factory drawing by M.A.G. of the damping device of the Fokker M.21 in Austrian service.
Drawing via Achim Engels 02 by Zac Yates, on Flickr

It is a lever arm that attaches to a friction disc which damps the forward and aft movement of the control column. Not exactly a trim device but maybe considered a forerunner?

Here is a photograph of the original Fokker damping device.
Archive photograph via Achim Engels 01 by Zac Yates, on Flickr

[PrzemoL]

Thank you Zac for your efforts to clarify the topic and to Mr. Engels for the answer. Very interesting and explaining a lot!

[AngryJazz]

Very interesting! Thanks for the pictures and explanation 

[IanB]

As I understand it, there was no elevator trim on British types either. The trim fitted to aircraft such as the DH4 adjusted the horizontal stabiliser. It wasn't a trim device as we know it now, which is an adjustable tab on the elevator to relieve control pressure and keep the elevator in the desired position. I stand to be corrected of course!

[WD]

What uncletony says is true. I really must look into getting back into flying Rise of Flight again this winter, and yes, the "live" controls are a pain, but that's how those a/c were then.

Warren

[Davos522]

I happened to have these to hand, since I'd copied them out of WWI Aero (not sure which issue, but I can look it up if anybody wants) the other day in the course of my Eindecker research project. According to these captions the device is actually an elevator lock used to keep the aircraft flying level while the pilot wrestled with the machine guns when clearing jams (Fokker's misappropriated interruptor gear being still in its infancy) rather than a way of trimming the a/c per se.





FWIW,

Dutch

[Rookie]

This very interesting stuff!

Thanks for posting it Zack and Dutch!

Willem