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All moving tailplane on the Supermarine Scimitar F.1


Max89
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It appears that the Supermarine Scimitar F.1 had an all moving tailplane, but I can also see lines on the tailplane surface suggesting the presence of elevators (highlighted in red below).

 

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Did the Scimitar actually have movable elevators, or am I just looking at panel lines?

 

There's also a little snippet on Wikipedia that suggests the aircraft had elevators that worked in tandem with the moving tail, but I don't see any sources or mentions of that anywhere else.

Edited by Max89
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To add to my original post, I found a cutaway for the Scimitar, and I don't really see anything on this diagram that suggests the presence of elevators or flaps on the tailplane.

 

PIs7rEj.jpeg

Edited by Max89
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  • Max89 changed the title to All moving tailplane on the Supermarine Scimitar F.1

According to the Putnam "Supermarine Aircraft" Andrews & Morgan book, it didn't have elevators. When referring to the control system issues at high Mach numbers, they say "...increased downwash over the slab-type all-flying tailplane , that is, with no independent elevator."

 

Some confusion in references might arise from the fact that the Type 508 predecessor to the Type 525 Scimitar DID have an all-flying tailplane with elevators, but the 508 had a butterfly tail, the elevators giving additional pitch control.

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2 hours ago, KevinK said:

According to the Putnam "Supermarine Aircraft" Andrews & Morgan book, it didn't have elevators. When referring to the control system issues at high Mach numbers, they say "...increased downwash over the slab-type all-flying tailplane , that is, with no independent elevator."

 

Some confusion in references might arise from the fact that the Type 508 predecessor to the Type 525 Scimitar DID have an all-flying tailplane with elevators, but the 508 had a butterfly tail, the elevators giving additional pitch control.

 

Thank you for the information.

 

I assume that rules out the presence of flaps on the Scimitar's tailplane as well (similiar to the Blackburn Buccaneer's tailplane flaps)?

Edited by Max89
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I believe so.

 

The only other possible hinged surface would be a tab. However, with a fully-powered all-flying tailplane, neither a trim tab nor an anti-servo tab would be needed, so I think it was just what Andrews & Morgan said.

 

The Buccaneer was, as you say, different. It had an all-moving tailplane and also elevators. It also used much more boundary-layer control (BLC) than did the Scimitar, with engine bleed air blown over wing, tailplane, flaps, ailerons and elevators. The Scimitar, only half a generation earlier, had been the first RN aircraft to use BLC, but only on the wing surfaces.

 

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Some aircraft with an all-moving tailplane did feature moveable tail surfaces mind, the Sea Vixen and Javelin for starters.  However I think this was due to the speed ranges these aircraft encountered and handling issues at the lower speed range (certainly the Sea Vixen).

The Buccaneer's tailplane trailing edge surfaces were flaps and operated with the main flaps.

 

The Scimitar doesn't have any trailing edge tabs etc though and the whole moving taiplane is trimmable through a separate electrical actuator.

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It's quite possible to have an all moving tailplane with hinged elevators which are geared to tailplane position. Pilot input can be directly, via hydraulics, to the main tailplane, movement of which also offsets the elevators appropriately through fixed gearing to basically modify the entire empenage aerofoil shape depending on control stick deflection (I seem to recall the H.S.Trident had this). Some aircraft even have the facility to 'ungear' the elevators from the tailplane so that they can be moved under hydraulic failure conditions as a manual reversion option. There is no fixed way of doing things and each manufacturer has their own favourite method.

Having said that, I'm unsure how the Scimitar went about things but there are several possibilities. However, having looked through my own references I do feel that the line one can see on some close ups seem to represent manufacturing seam lines. The giveaway might have been a visible elevator/tailplane deflection under fully nose up conditions, particularly during landing but none is visible so I do not believe that this was anything other than a one piece tailplane.

Edited by viscount806x
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46 minutes ago, viscount806x said:

It's quite possible to have an all moving tailplane with hinged elevators which are geared to tailplane position. Pilot input can be directly, via hydraulics, to the main tailplane, movement of which also offsets the elevators appropriately through fixed gearing to basically modify the entire empenage aerofoil shape depending on control stick deflection (I seem to recall the H.S.Trident had this). Some aircraft even have the facility to 'ungear' the elevators from the tailplane so that they can be moved under hydraulic failure conditions as a manual reversion option. There is no fixed way of doing things and each manufacturer has their own favourite method.

Having said that, I'm unsure how the Scimitar went about things but there are several possibilities.

 

All true, and there are examples of many types which can be quoted. Desirable control authority over the aircraft's speed range is the underlying requirement and this is dependent on a variety of factors including variables such as downwash at the tailplane location. c.g. range, etc.

 

However, the OP specifically asked about the Scimitar.

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Reading from the original photo, the first clue is that the line you identified isn't nearly broad enough to be the hinge line of a separate surface.  Especially in the 1950s, but still today, an elevator would have a marked indentation all the way along, with the profile of its leading edge visible just aft of the fixed surface.  And to confirm that, the line looks just like the definite panel line ahead of it.  Doesn't help when references are (at best) mistaken, does it?

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This is what it says in the pilots notes, to me it sounds like the set up on the Canberra, 

7. Tailplane trim and indicator

(a) A four-way switch, at the top of the control column,

when operated fore-and-aft i.e., in line with the thumb,

provides tailplane trim. Operating the switch completes the

circuit to an electric actuator which resets the neutral

datums of the tailplane feel simulators , thus trimming the

tailplane.

(b) The position of the tail plain is shown on a TAILPLANE

indicator on the instrument panel. Two positions of the

 

aircraft Controls and Instruments

indicator, one marked FU and the other FD how the

trimmed position for take-off with the flap up and fl aps

down, respectively.

(c) A DUPLICATE TRIM- NOSE UP/ NOSE DOWN

switch under a flap on the port console, is provided as an

alternative control for tailplane trimming if the four-way

switch fails. Lifting the flap disconnect the electrical supply

to the fore-and-aft circuit of the four-way switch and

completes the circuits to the duplicate witch.

(d) Auto-trimming

The tailplane is automatically trimmed when the flaps are

-operated by the normal system .

 

John

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It's the other way around from the Canberra John.

On the Scimitar the whole single piece tailplane moves to give 'elevator' control (an 'all flying tail'), via a hydraulic system.  The tailplane is also moved, or adjusted for vertical trim, by an electrical actuator.

On the Canberra the whole tailplane moves for trim adjustment only, the separate trailing edge elevators provide control.

 

As Kevin K says, there are so many variables to a tailplane set up, the Scimitar style is what would become common for high performance jets.

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16 hours ago, 71chally said:

It's the other way around from the Canberra John.

On the Scimitar the whole single piece tailplane moves to give 'elevator' control (an 'all flying tail'), via a hydraulic system.  The tailplane is also moved, or adjusted for vertical trim, by an electrical actuator.

On the Canberra the whole tailplane moves for trim adjustment only, the separate trailing edge elevators provide control.

 

As Kevin K says, there are so many variables to a tailplane set up, the Scimitar style is what would become common for high performance jets.

We see similar setups on civil airliners depending on the makers aspirations on cruising mach numbers. Slab tailplanes (e.g.Trident, L1011) give a reliable pitch control within the high mach regions where the tailplane mach shock wave might otherwise render conventional elevators unusable or at least dangerously compromised. If one accepts a high but moderate cruise mach no. but staying below the compressibilty region, say M0.8 ish (or less) then conventional elevator and tailplane controls can be built in during design (e.g. B737,747,757,767) with benefits in better overall form drag characteristics and very wide fore and aft trim adjustments - important on a long body aeroplane, and therefore giving enhanced operating economics, a major plus point when the company is paying heavily for the fuel and range is a factor too.. We don't need to consider any of this for a gentlemans/gentleladies  aerial interceptor where speed and seamless mach transition is everything.

Cheers, Nige

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On 11/11/2021 at 2:10 PM, canberra kid said:

This is what it says in the pilots notes, to me it sounds like the set up on the Canberra, 

7. Tailplane trim and indicator

(a) A four-way switch, at the top of the control column,

when operated fore-and-aft i.e., in line with the thumb,

provides tailplane trim. Operating the switch completes the

circuit to an electric actuator which resets the neutral

datums of the tailplane feel simulators , thus trimming the

tailplane.

(b) The position of the tail plain is shown on a TAILPLANE

indicator on the instrument panel. Two positions of the

 

aircraft Controls and Instruments

indicator, one marked FU and the other FD how the

trimmed position for take-off with the flap up and fl aps

down, respectively.

(c) A DUPLICATE TRIM- NOSE UP/ NOSE DOWN

switch under a flap on the port console, is provided as an

alternative control for tailplane trimming if the four-way

switch fails. Lifting the flap disconnect the electrical supply

to the fore-and-aft circuit of the four-way switch and

completes the circuits to the duplicate witch.

(d) Auto-trimming

The tailplane is automatically trimmed when the flaps are

-operated by the normal system .

 

John

 

I don't see anything in these pilots notes suggesting the presence of elevators, trim tabs, flaps or any other movable control surface on the tailplane.

 

As 71chally says, it sounds like trimming was done by moving the entire tailplane slab and holding it in position.

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