Sutton Harness attachment points of lap straps

[Basilisk]

I know that this question had been asked in the past, but unfortunately all the old posts don't show the pictures anymore which Edgar attached in the past.

Anyway, I am looking for information of the attachment points of the lap straps in the Hurricane and Spitfire BoB era aircraft. Are they attached to the seat or the cockpit framework? And where / how? There is lots of information how the shoulder straps are attached, but I can't find any pictures showing the lap straps attachments as they are out of sight on all the pictures I have seen.

Any information is much appreciated.

Cheers, Peter

[Edgar]

[Basilisk]

Thanks Edgar for attaching this drawing. So it looks like that the lap strap is attached on the side of the seat.

Cheers, Peter

[Edgar]

Being metal, it would have been relatively easy; in 1943/4, when the Spitfire straps needed to be moved, the plastic seat had to have minimum thickness, specially-strengthened material.

[tarlucan]

Edgar

Sorry to continue this thread but I am still unnsure as to the location of the attachment points for straps 2 & 3 of the Sutton harness (with eyelets and pin) on an Aug 1940 aircraft. Strap 3 (right thigh) appears to route through the slot in the right side of the seat, but was this just a practice that developed to avoid entangling the seat raising mechanism. If the slot was designed to route the lap strap, why wasn't the same arrangement on the other side. Was it possible that the slots in the side and back were simply designed to assist removal during servicing and their subsequent use to route the harness was something of an "in service adaptation"? To this end, what was the purpose of the 'flare" on the left hand side of the seat? Does Fig 8 show both straps attached to the very bottom of the seat itself or was there some structural cross member that ran underneath which they attached to at the end on both sides? The former does not seem to imply integral strength at the location point given the material from which the early seats were made.

[Edgar]

I haven't seen a seat with the early Sutton arrangement, so can only guess that they used, somehow, the stiffening bar underneath as an anchor point.

The pin wasn't fitted to strap 2 (actually right thigh) or 3 (left thigh); it was on strap 1 (left shoulder,) and the clip was attached to strap 4 (right shoulder.) With no mechanism on the left seat wall, there was no need for a slot.

The "flare," on the left wall, was to give the ripcord room, so that it didn't chafe; it was also lined with basil leather, to help with that.

The slot, in the backrest, remains a bone of contention; on metal seats it was designed for the shoulder straps to pass through, but a friend, who works on Spitfires, maintains that the plastic would never have coped with the strain; he also points out that you never see marks, on the slot, which would have been caused by the straps. He uses it as a simple handhold, since the Spitfire seat can only be removed with it at the lowest point of its travel, and, especially with the extra weight of armour plate, it takes two to lift it out, and a third to take it from them.

[tarlucan]

Edgar

Thank you for your reply. Which mark does the seat in the photo come from? Clearly, it was felt that the seat was strong enough to attach a thigh strap in this case. Would the right hand side have attached in a similiar manner? Surely that would have interferred with the raising mechanism. If so, would it attach at the base? However, I would have thought that would produce an uneven restraint geometry for the Pilot.

Edited September 1, 2015 by tarlucan

[Edgar]

This is the other side of the same seat, and the fastening is clear of any moving parts; I've no idea of the Mark, since it was sitting in the middle of an aircraft rebuilder's shop floor, surrounded by half a dozen airframes (Mk.IX would seem favourite, though.)