Questions about the Sea Vixen

[Max89]

I've come to learn that there are two main production variants for the Sea Vixen: FAW1 and FAW2. I also know that many FAW1 aircraft were converted to FAW2, but there were a handful that were built as FAW2 at the factory.

 

With that said, I have two questions...

 

1. Does anyone have serial numbers for the Sea Vixens that were built as FAW2 at the factory?
2. Were there any externally visible differences between aircraft that were converted from FAW1 to FAW2 versus the aircraft that were built as FAW2?

 

Thanks in advance!

Edited May 22, 2021 by Max89

[David Womby]

According to "de Havilland Vampire, Venom and Sea Vixen by Philip Birtles,  XP919-925, 953-959 and XS576-590 were the ones built as FAW2s.

 

From looking at lots of photos during my recent build, the only things I could see different were some converted FAW1s retained the early style pilot canopy (see here: Early Sea Vixen canopy) and the original, non-bulged, observers hatch  (at least for a while). 

 

I also believe some FAW2s may have left the factory with the early canopy and hatch too but I am not sure about that.  You need to check photos carefully for the actual airframe you plan to build.

 

David

[Selwyn]

3 hours ago, David Womby said:

According to "de Havilland Vampire, Venom and Sea Vixen by Philip Birtles,  XP919-925, 953-959 and XS576-590 were the ones built as FAW2s.

 

From looking at lots of photos during my recent build, the only things I could see different were some converted FAW1s retained the early style pilot canopy (see here: Early Sea Vixen canopy) and the original, non-bulged, observers hatch  (at least for a while). 

 

I also believe some FAW2s may have left the factory with the early canopy and hatch too but I am not sure about that.  You need to check photos carefully for the actual airframe you plan to build.

 

David

I seem to remember sombody back in the mists of time mentioning that the pinion tanks were different in the twin boom areas, in that it was visually obvious that the pinion tanks on the FAW1 to 2 rebuilds were "added on," items, but the new builds were "built as such" with no clear demarcation.

 

Selwyn

[Max89]

Thank you gents. I'll get around to the pinion tanks in a bit, but interesting to note that the canopies were different.

 

There's some good material on the difference in canopies in this thread: https://www.britmodeller.com/forums/index.php?/topic/235093167-sea-vixen-early-canopy/&do=findComment&comment=4079277

 

Does anyone have pictures of what the observer's hatch looked like on the FAW1 vs the FAW2? I see that the latter was "bulged" but I'm having a hard time finding images that help me to spot the difference.

Edited May 22, 2021 by Max89

[Max89]

Bump.

 

Anyone have pictures of the observer's hatch on the FAW1 vs the FAW2? I don't know how to spot the difference between the two.

[David Womby]

3 hours ago, Max89 said:

Bump.

 

Anyone have pictures of the observer's hatch on the FAW1 vs the FAW2? I don't know how to spot the difference between the two.

Here's a comparison clipped from photos I have found around the web.  I'm afraid I can't remember where each came from to give the owners credit.

 

The later bulged clear one apparently usually had a black blind over the inside to keep out the light.

 

David

 

 

[Max89]

Does anyone know what these openings are (circled in red)? Were they actuated/movable or were they fixed?

 

[71chally]

They are the boundary layer air outlets, the inlets of which are just inside the main engine intakes on the inner walls of the fuselage.  They don't move at at all.

There's a good view of them in that pic of '247'.

 

Getting back to the main question, there are no differences between an FAW.2 production machine or one that has been converted.

The hatch and canopy changes came about because the ejection seats and their operation were continuously updated and as such were modification states and not related to the aircraft Mk.

That's why converted aircraft and early production FAW.2s were seen with early style, before they were modified to later canopies/hatches and the command ejection system.

The new style bulged hatch was designed to eject right through, being frangible. It didn't have a blind, they were painted black from the inside.

 

The principle difference between an FAW.1 and 2 was actually the armament, the former relying on Firestreak missiles where as the latter was designed to carry Red Top. This necessitated carrying extra equipment and the extended booms were designed to house this. The opportunity was taken to add extra fuel tanks in the forward part of this booms.

 

[Max89]

6 hours ago, 71chally said:

They are the boundary layer air outlets, the inlets of which are just inside the main engine intakes on the inner walls of the fuselage.  They don't move at at all.

There's a good view of them in that pic of '247'.

 

Getting back to the main question, there are no differences between an FAW.2 production machine or one that has been converted.

The hatch and canopy changes came about because the ejection seats and their operation were continuously updated and as such were modification states and not related to the aircraft Mk.

That's why converted aircraft and early production FAW.2s were seen with early style, before they were modified to later canopies/hatches and the command ejection system.

The new style bulged hatch was designed to eject right through, being frangible. It didn't have a blind, they were painted black from the inside.

 

The principle difference between an FAW.1 and 2 was actually the armament, the former relying on Firestreak missiles where as the latter was designed to carry Red Top. This necessitated carrying extra equipment and the extended booms were designed to house this. The opportunity was taken to add extra fuel tanks in the forward part of this booms.

 

 

Interesting.

 

Would XS590 have been a late production FAW.2? And would it have rolled off the production line with the updated canopy, hatch and extended booms already included?

[71chally]

It was the last Sea Vixen built, being completed in early 1966.  Without pictures or very precise production records it would be hard to tell which canopies it originally had.

There is a picture of it dated 1968 which shows it with the original type metal observer's hatch.

[Max89]

Another question about the openings on the back of the fuselage, lol.

 

What are the openings circled in red in the image below? Are they all boundary layer outlets as well?

 

[Ben Brown]

I’m not a Sea Vixen expert, but those four vents are probably outlets for cooling air used by engine accessories. Note how they are located near NACA duct intakes and they are situated in the same location relative to each engine.

 

Ben

[71chally]

Definitely not boundary layer outlets, without checking I would say various engine pressure relief outlets.

[Max89]

9 hours ago, 71chally said:

Definitely not boundary layer outlets, without checking I would say various engine pressure relief outlets.

 

I see.

 

I'm also wondering if any of the outlets circled in red could be opened and closed.

 

If they could be closed, I can just smooth them out in my 3d model instead of actually modelling in the outlets.

 

This is the only diagram I've been able to find, but sadly it's all in Russian. Not much use in translating it either because the image is cropped.

 

Edited January 31, 2022 by Max89

[Ben Brown]

They’re probably heat exchanger outlets for oil coolers, generators, or other kind of engine accessory, which are often just open ended ducts. They’re the outlets for those nearby NACA ducts. Of course, as my luck with reference photos usually goes, the best photos I’ve found of this area are of a museum example which has the outlets taped over!

 

EDIT: They're definitely fixed open:

 

Ben

Edited January 31, 2022 by Ben Brown