Aileron/rudder interconnect
 

Flew a Grob 115D2 Heron last week. My Tommy was in for maintenance and the organisation has some ex-Navy Herons. Was recommended to have an aeros session in the Heron by a CAA flight ops man of my acquaintaince.

Delightful aeroplane. A very good compromise. But it has an aileron/rudder interconnect - why? Apart from the stick moving while I steered with the pedals on the ground, I didn't notice it in the air while aerobatting, particularly during stall turns, where I might have expected it to interfere. Why did the manufacturers put in this interconnect? It appears to serve no useful purpose, particularly in the role for which this aeroplane is intended. It didn't help, and it didn't get in the way. And it operates in the wrong sense for x-wind landings (it applies left aileron for left pedal, and vice versa).

My understanding is that such interconnects are used to provide for 'balanced' turns without pilot rudder input; or can mimic better lateral (Lv) stability when sideslipping by encouraging the pilot to apply more aileron force with rudder.

The spring effect was pretty weak. Does the Tutor (G115E) have the same interconnect?

Other than that, a super light aeroplane. Great all-round view, easy to use systems, and very pleasant control system feel, even though the stick is pivoted under the seat. Rolling's a bit ponderous but probably no worse than the Chippy I fly. I might even venture to suggest that rolling aside, it's better than the Bulldog. But why have an aileron/rudder interconnect?

I-M

Unless requirements have changed there used to be one that said if you abandoned the controls in a steady heading sideslip the aircraft had to tend to level its wings and not just sit there banked. I have worked on light aircraft programmes where it was necessary to add the interconnect of which you speak in order to achieve this.

I have no knowledge of the Grob.

It is no huge deal but I am not sure I like it added solely for this reason – just like you I surmise.

JF

I can't answer any of your questions except to say that the G115E does have the spring interconnect. If you sit on the ground and let go of the stick it will move around in unison with the rudder. The spring feels quite weak however, certainly not concious of feeling any pressure when holding the stick central while taxiing on the ground.

ASI

The Beech Bonanza (A36) and the CT4B Airtrainer also have the interconnect. Interestingly, the CT4A Airtrainer (as supplied to the RAAF) does not have the interconnect.

There was some extensive "discussion"and testing at ARDU of the CT4A with the 'report' highlighting control line breakout forces in the rudder system as being of 'concern'.

When the CT4B was being (re)certified in NZ for Australian use, the bandaid fix for a perceived problem by an ex Farnborough bright spark (not a pilot) was to fit an airleron/rudder interconnect. What a dog to fly aero's in, what a tiresome dog to fly in formation.

tipsy
:yuk: :yuk: furball:yuk: :yuk:
Don't lie, steal or cheat, the Government hates competition.:ok:

Many thanks for the contributions - more food for thought!

Piper seemed quite fond of it in a few of their a/c. I bloody hate it. I'm quite capable of coordinating a roll or turn and intensely dislike having to fight the interconnect on nearly every landing (how many landings have zero x-wind?).

From the RAF Tutor Operating Guide:

" The aileron controls are connected to the rudder controls via a spring device in the centre console. Movement of the rudder or aileron controls will produce a complementary increase in control feedback force"

Have you ever really noticed it in flight though? Maybe it's just me, but I've not really had any concious thoughts of feeling it working against me.

ASI

Jetstream 31 / 32 have an interconnect system. Only quote in maintenance manual is " To assist recovery from certain flight attitudes, the rudder and aileron cable control system are interconnected." Not much! However they spring system is lightly loaded (7lbs) so unless you get in on of those situations where the passengers have all either been flung into the baggage area at the back or have landed on the crews laps I would assume in normal flight with co-ordinated turns it would not be noticed.

More modern aircaft CRJs for example do not require the use of rudder in normal flight as the flight control system works all that turn stuff out. Might be done using elecronics but it is still a aileron / rudder interconnect system.

I always understood that the interconnect on some of Mr. Piper's models was to meet a certification requirement for a particular roll rate at threshold speed in the landing configuration using ailerons only. However that was only hearsay, I never saw it written anywhere authoritative.