Beaufighter II tailplanes

[The wooksta V2.0]

Is there any reference to when specific airframes received the dihedral tailplanes?

Looking at making a start on one if the four aircraft that 618 sqn used (Aifix Beau with Alleyway wing/engine conversion) and need to know if I have to order a set of straight tailplanes to go with it!

[MACALAIN]

There are not a lot Beaufighter Mk II with V tail, most are with flat tail

 

https://www.pinterest.com/pin/396598310904802246/

 

This is one with V tail

 

Alain

[fishplanebeer]

There are pics showing the IIF with both flat and V tail planes so the only reliable route as always is to pick a specific aircraft and go with that. Plenty of photos exist of the MK IIF so you should have quite a few to choose from.

 

Regards

Colin.

[fishplanebeer]

Sorry, just to add that Hobby 2000 currently do the Beaufighter IF/IC and VIF (all ex-Hasegawa) with straight tails if you decide to go this route.

 

Regards

Colin.

[The wooksta V2.0]

I've remembered I have a set of flat tailplanes I bought last year, a High Planes conversion from Freightdog rather than wait for Alleycat's glacially slow delivery schedule, so that's not the real problem. I've the serials for four aircraft to choose from as I want to do one of the four that 618 Sqn were using in '43/'44.  Finding a photo is the hard part.

[tonyot]

I reckon that the V tails were fitted retrospectively `on unit' to selected Beau II`s which were still in service mate. 

[JWM]

The span of flat tailplane was I think smaller then that of the later V type, but it is easy to convert just by proper cut

[dalea]

Both the HiPlanes (sized for Airfix in the blurb) and the AML one are certainly smaller in span

[2996 Victor]

Hi @The wooksta V2.0,

 

did you get any further with this? I have a similar project planned, and I'd be interested to know how you're getting on.

 

I haven't yet ordered the AlleyCat conversion, as I'm not sure whether to go "early" or "late" with regard to the exhausts.

 

Can anyone shed any light on the relative numbers of the two types of exhaust? Is there any correlation to the type of exhaust and the retro-fitting of dihedral tail-planes?

 

Many thanks and best regards,

Mark

[Graham Boak]

Do you actually mean smaller in span, that is the distance between the tips in plan view, or in length?  They were longer, because if you tipped up (added dihedral to) the original tailplane to provide greater side area and hence directional stability (yaw). you were reducing the area in the plan view so reducing the longitudinal stability (pitch).  The obvious first thought is to lengthen the tailplane so that the tailplane, with dihedral, produced the same plan area as the original tail (assuming that was considered good enough in the first place).  I don't know whether Bristol actually did this or introduced some other size for (no doubt) very good reasons.

 

I very much doubt that this had any connection to the change in exhausts.  There appears to be no technical link.

[2996 Victor]

35 minutes ago, Graham Boak said:

Do you actually mean smaller in span, that is the distance between the tips in plan view, or in length?  They were longer, because if you tipped up (added dihedral to) the original tailplane to provide greater side area and hence directional stability (yaw). you were reducing the area in the plan view so reducing the longitudinal stability (pitch).  The obvious first thought is to lengthen the tailplane so that the tailplane, with dihedral, produced the same plan area as the original tail (assuming that was considered good enough in the first place).  I don't know whether Bristol actually did this or introduced some other size for (no doubt) very good reasons.

 

I very much doubt that this had any connection to the change in exhausts.  There appears to be no technical link.

Hi Graham,

 

I was aware that the actual span was the same, meaning that the dihedral tail-planes were actually longer. The improvement in longitudinal stability I wasn't aware of - I presumed it was something to do with roll characteristics.

 

As regards tail-planes vs exhausts, I wondered whether there was simply a correlation in terms of timeline. In other words, were the shrouded exhausts seen with the horizontal tail-planes?

 

Incidentally, I've got the WingLeader Beaufighter book on order, which I hope will provide some insight. Somewhere, I've got Victor Bingham's monograph. I'm also looking to find a copy of Jerry Scutts' book. Are there any others that are worth their weight in salt?

 

Cheers,

Mark

[Dave Swindell]

7 minutes ago, 2996 Victor said:

I was aware that the actual span was the same, meaning that the dihedral tail-planes were actually longer.

I was under the impression that the span remained the same, and the tailplanes were unchanged.

On the flat tail the tailplanes were mounted directly to the fuselage, but when the dihedral tail was introduced the same tailplanes were mounted to a short flat central section which maintained the span and had angled outer ribs to give the dihedral.

[Graham Boak]

Mark:  Adding rear side area improves the directional stability, something which had suffered by the additional forward side area of the Merlin engines.  Adding dihedral would improve the lateral stability (roll) but that adding it only at the rear is a bit unusual - but certainly easier than adding it to the wings.  How this would actually affect things in greater detail is beyond the limits of my knowledge.

 

Dave:  Looking at the size of the dihedral, I think it would need rather more than a short central section to match the lost plan area.  Given the bits in model form, it should be easy to work out the respective lengths (as a quick equivalent for the areas).  They did introduce larger tailplanes at some stage.

 

I haven't bought, nor read, a Beaufighter book for some years, so can't recommend anything specific for the early variants (Terry Higgins for the torpedo bombers)..  I shall however reread the Putnam Bristol Aircraft for revision on the tail changes.  (later)  OK, the usually reliable C.H. Barnes has no mention of a  larger tail until later in the life of the Coastal variants, when increases in equipment weight reduced stability.  Interestingly the night fighter pilots apparently preferred to live with the slight longitudinal instability in return for a slightly more agile aircraft.   Barnes does quote 12 degrees for the dihedral, which isn't a lot and less than I had thought.  I think I've got the Jerry Scutts book upstairs... Another time, perhaps.

[Dave Swindell]

13 minutes ago, Graham Boak said:

They did introduce larger tailplanes at some stage.

There was a change in ratio of tailplane to elevator area at some point but the total area and outline remaiined the same, need to go through refs to see if we're talking about the same thing though

[Graham Boak]

You caught me in the middle of editing, as I have just read Jerry's book.  The first thing that struck me was that there was an increase in span of 2ft between the Mk.I and the Mk.X.  In the text, he says that it was a combination of this increase in span and the dihedral that was introduced to solve the instability problem.  The dihedral would have reduced the span, but only by a few inches.  (Thank you cosines, and a very old calculator found in a desk drawer!)  So we are looking at moving the original tailplane outboard by some 13 inches each side.  I'm afraid I've no idea whether this is accurately reflected in any of the kits.  To an aerodynamicist, this is a larger tailplane.  To a production engineer, this is a fuselage modification.

 

PS  One of the alternatives tried, and found successful, was a large dorsal strake, which was not used but later adopted for the torpedo bombers already fitted with the dihedral tail.  To me, that seems as though the problems had been eased rather than gone away, and the aerodynamics office eventually got their way over the production guys.  By then there were no Beaufighter fighter pilots to object.

[2996 Victor]

1 hour ago, Graham Boak said:

Mark:  Adding rear side area improves the directional stability, something which had suffered by the additional forward side area of the Merlin engines.  Adding dihedral would improve the lateral stability (roll) but that adding it only at the rear is a bit unusual - but certainly easier than adding it to the wings.  How this would actually affect things in greater detail is beyond the limits of my knowledge.

Hi Graham,

 

That's fascinating and a side effect of fitting a different "format" of engine that I'd never have considered. But having had it pointed out seems obvious!

 

41 minutes ago, Graham Boak said:

So we are looking at moving the original tailplane outboard by some 13 inches each side.

That's quite a large increase! I read somewhere that the outline in plan form was unchanged, so that the tail-planes on dihedral Beaus were slightly longer but appeared identical to horizontal Beaus when viewed from above. But 13 inches apiece is much greater. 

 

44 minutes ago, Graham Boak said:

I'm afraid I've no idea whether this is accurately reflected in any of the kits.

When my horizontal tail-planes arrive, I'll have a quick measure!

 

45 minutes ago, Graham Boak said:

a large dorsal strake

I wondered why this was added, but it makes sense where directional stability is of paramount importance!

 

Thanks for this, Graham, is enormously appreciated.

 

Cheers,

Mark

[The wooksta V2.0]

I bit the bullet and ordered the Alleycat ones and they arrived in a reasonable space of time.

 

Fit isn't too good but filler has been deployed.  TBH, I'm not that keen on the fit of the Airfix new tool Beaufighter full stop.  The plastic is too flexible and the fuselage never wants to go together.

 

I'm going to take a gamble on the four aircraft that 618 received being in overall night with the earlier style angled tubes, based on 333 (Norwegian) sqn having a similar aircraft in the same 1943 timeframe.  Without a photo, who is to prove I'm wrong?

[2996 Victor]

7 hours ago, The wooksta V2.0 said:

I bit the bullet and ordered the Alleycat ones and they arrived in a reasonable space of time.

 

Fit isn't too good but filler has been deployed.  TBH, I'm not that keen on the fit of the Airfix new tool Beaufighter full stop.  The plastic is too flexible and the fuselage never wants to go together.

 

I'm going to take a gamble on the four aircraft that 618 received being in overall night with the earlier style angled tubes, based on 333 (Norwegian) sqn having a similar aircraft in the same 1943 timeframe.  Without a photo, who is to prove I'm wrong?

Thanks for the update - any photos of progress?  

 

Cheers,

Mark

[Graham Boak]

The only photo in Scutts of a Mk.II with the V tail, other than experimental, is of a very late FAA example.  Another FAA example still has the flat tail.  There is a report in the text of a squadron  (presumably Mk.I/VI) changing the tails on the unit, but in view of what is involved I suspect this is a "bar story".  There is a distinct straight section - perhaps I could look at my Hasegawa Mk.X?  OK, indeed I could - later.

 

I spent a long time looking for different exhaust layouts on Hercules-engined examples, before remembering that this was supposed to be a Mk.II thread.  I found four different exhaust systems. the most common being a semi-shrouded type with a solid upper section and the exhausts coming out of the lower section.  The straight-through original seems to have disappeared early on (unsurprisingly) and the 12-exhausts style later.  This would appear to be unsuitable for night use, but are seen on a 1943 Polish example, so perhaps the inner sides were shrouded?

[Graham Boak]

The extension from the side of the dihedral tailplane in the Hasegawa kit is some 3mm, Imm on the fuselage and 2mm on the tailplane,  So a tad short of the 4+mm required but I'm letting them off.