Design of Yolk

[PAXboy]

What drives the design of the steering yolk? I have seen many examples in aircraft over the years from the '8' to the 'W' and the 'U'.

I wonder if the design is largely 'design' or is it intended to affect the way in which the pilot approaches the handling of the particular aircraft? Perhaps the most interesting is the inverted 'W' in Conc. It resembles the 'ape hanger' handlebars of 1970's Harleys (a coincidence? ;)) As I read about the special handling characteristics of this machine, I wondered if the design had more than 'futuristic look' about it?

When you convert to a new machine, how does the new yolk affect that? Side-stickers should not set out to upset their yolking colleagues. :p

[pigboat]

I've often wondered eggzactly the same thing myself.

[John Farley]

PAXboy

Interesting pair of questions. A complete answer to your first one could fill a small book while the second is a lot easier.

So Q2 first. On conversion, by the time you are half way round your first circuit you will probably no longer notice whatever control yoke your hands are using (unless it has been badly designed - which is unlikely unless the aircraft type goes back say 40 years or more).All you will be conscious of will be the forces and displacements you are using and whether they allow you to control the attitude of the aircraft to your satisfaction. Such matters tend not to be determined by the shape of the thing you are holding.

That probably gives you a clue about the answer to Q1. The primary purpose of the yoke is to allow you to apply forces and displacements. In pre power steering days much muscle could be needed to deflect controls into the airflow. Hence the leverage that could be applied was important in sizing the yoke so far as the ailerons were concerned. For the elevators it was necessary to put the yoke on top of a suitably long column to get the fore and aft leverage to make the push and pull part of the job doable. Where the yoke was mounted on a rod that came and went in and out of the panel (as it were) then there was a lever somewhere below in the works which had the same effect, it was just kept away from your legs. Power controls sorted out the leverage issues of course.

Then there is the need for the necessary movements to be possible without the yoke getting too close to you chest or thighs. Not that easy when considering the large size range of pilots. Toss in the need for pilots to be able to move themselves up and down to see out properly and the things can be quite a problem to resolve to everyone’s satisfaction.

All this can be made harder if the cockpit is on the small side. Here, the rams horn shape that you mentioned in Concorde can be a help in missing your thighs when full aileron control is applied, especially if a lot of rudder is also needed for asymmetric reasons. The leg you push with tends to go down and out of the way as it gets straighter, but the other foot moves towards you, that knee tends to stick up and foul the aileron inputs (even foul the elevator inputs in the DC3 for example – a poor design case so far as this topic is concerned but it was done 70 years ago)

The Trident also had a Concorde like yoke. Both aircraft benefited from less yoke inflicted obstruction of the pilots view of the instrument panel. Having to peer over and round the yoke to see and reach something can be a right pain.

I will stop there as I am sure you get the drift that there are a bunch of things that drive yoke design.

Regards
JF

[Onan the Clumsy]

I just thought you needed to have it balanced and carry as much as possible, therefore it was designed for TWO buckets of milk.


On another note (don't mean to hijack here but) why does a car's steering wheel not revolve around a point in the centre? It seems like most cars I drive although they have a circular steering wheel, have a little more above than below the point of rotation.

[PAXboy]

Onan: As topic starter, I hereby give my gracious permission for topic hijack. :D

With cars, I have noticed this too and reckon it is a 'cheat' to allow easier access when getting in to the driving seat. Perhpas this started in the US where people are (ahem) a trifle larger than in the UK. "More trifle, Vicar?" Of course, no one is accusing Texas residents of being over-sized! :rolleyes:

JF, many thanks for that run down of factors. Very helpful.

[Onan the Clumsy]

PAXboy - excellent answer.

[strafer]

ASFKAP - I read your post half an hour ago. I'm still laughing.

[PAXboy]

AFSKAP: That was eggecrable but I have to admit that it broke me up. I'm glad that we are not all hard boiled in this forum. The next time I see a pilot with egg on his face, I won't make a yoke about it.

[safetypee]

I traced the inverted W yoke, ‘rams horn’, back to the HS 125 (Aahh de Havilland). I suspect that as explained by JF that reduced flight deck space and the need for large amounts of rudder / aileron was a major driver in its use. The rams horn configuration gave a relaxed hand position and certainly gave a clear view of the flight instruments. A further advantage was that it enabled easy control of the aircraft on the ground when using ailerons steering. This is an unusual characteristic of the 125 (125-800++) where the ailerons aided directional control on the runway – particularly after engine failure. The control input via the yoke was akin to steering a bicycle.
The rams horn was used on the Trident (HS121), but not on the HS146. I assume that the 125 design preceded the Trident. Any information on the Comet or its DH predecessors; or why the 146 did not follow the DH design?

[PAXboy]

SP: I'm sorry - but I really don't understand what you are talking about. Why are you putting all this junk about control columns in a thread about eggs?? Really, the way some people hijack a thread ..... :*

[ETOPS773]

HINT...
which looks better:
Yolk
Yoke..

Maybe a poll to decide??