Hawker Typhoon Mk. 1 B

[Bo Roberts]

Did this a/c ever use the larger Tempest horizontal tailplane? When were they installed??

Thanks,

Bo Roberts

[hacker]

depends on what squadron and what time period you wish to build. The Tempest tail planes were either added during manufacturing of later production models or they were retrofitted in the field during maintenance. This included the changing from a 3 prop to a 4 prop propeller and the bubble canopy. So you will have to check if its a retro fit what time period you wish to do and whether its a new aircraft. The 1/32 Typhoon l did was in a time period of Jan 45 which by that time had all the mods added.

later

[AnonymousA667]

Bubble hoods were tested as early as January 1943, but didn't become standard fit until September of that year. Tempest tail planes and four blade props were introduced from March 1944 IIRC.

peebeep

[Test Graham]

I don't know that they were ever retrofitted to any aircraft, and certainly not in the field during maintenance. There was a major programme of reconditioning old Typhoons for 2 TAF mid-to-late 1945, but this was done in MUs and did not involve changing the tailplane.

[MikeC]

Sources vary, and it's difficult to make sense of them. I believe that it was perfectly possible to see a Typhoon with a four-blade prop and Typhoon tailplane, although always with a bubble hood. The Tempest tailplane was fitted to cure stability problems introduced by the four-bladed prop. However, a quick re-skim through Thomas and Shores ("The Typhoon and Tempest Story") implies - although as far as I can tell never actually states - that a Typhoon with a four-blader always had a Tempest tailplane. Use your own judgement from your own sources, any further info welcome.

[Test Graham]

I believe you have this the wrong way around. Test aircraft aside, of course. The 4-blade prop was desired to reduce vibration, plus it gave a little extra thrust. However, it destabilised the aircraft so the production was delayed until after the introduction of the enlarged Tempest tailplane. So you will find 3-bladers in service with a wide tailplane but the opposite was not cleared for service. Yes, all with bubble canopies. I believe the changes occurred in the MB/MN serial batches, but not at a single serial.

[Bo Roberts]

You Guys are the GREATEST!! If it's British, this is the source of knowledge. (Not to mean y'all don't know other nationally stuff as well. )

I'm building a 4-blade, bubble canopy that operated after D-Day, so I'm going with the Tempest tails!!

Bo Roberts

[JosephLalor]

Regarding Typhoons with three-blade props and Tempest tail-planes, it's my understanding that there was a problem with oil leaks from the four-blade propellers which caused some late production aircraft with Tempest tail-planes to be reconverted back to the three-blade prop. The vibration expected with the three-blade prop was supposed to be damped by 10lb ballast weights in the tail-planes. The leaks were supposedly cured by seals imported from the US.

My guess is that a bubble canopied Typhoon in the MN or SW serial range with a three-blade prop will have the Tempest tail-plane, and if it's in the JR range it'll have the early smaller tail-plane which doesn't encroach on the Sky band.

As usual, expecting to be put right there.

Joseph

Edited May 21, 2008 by JosephLalor

[Edgar]

I have a copy of a memo, from AVM Breakey, dated 25-3-44, in which he talks of the test introduction, of the 4-blade propellor, and the Tempest tailplane, as already having been carried out. At that time, they were testing the American seals, on the 4-blade props, and results were encouraging, enough, for them to order some, direct from the States, but they would not be available before May, so alternatives were to be made, here, as well.

Be wary of using the tail band as a visual indicator of the presence, or otherwise, of the Tempest tail. Conversions did encroach onto the band, but later production a/c simply had the band moved forward slightly. A better indication (but difficult to see) is that the l/e, of the Tempest tail, encroached onto the fishplates.

Edgar

[Test Graham]

The weights in the tailplane were to change the flutter characteristics. Previously these had been on extended arms but the arms had failed due to metal fatigue caused by vibration. Without these balance weights, the aircraft could reach speeds where flutter could occur in the tailplane, ripping the tail off. This was not caused by the vibration, but by the aerodynamic forces on the tailplane and its structural design - a resonance effect. So these weights were not introduced as a direct damper on the vibration as such, but an alternative design solution to the weaker arms. The vibration caused other problems, including pilot comfort and general wear and tear.

The bigger Tempest tailplane had different aerodynamics loads and structural design, so that flutter was not a problem. As long as the weights remained attached, it was no problem on the standard Typhoon, either! However, a check of service Typhoons did show that a number had reached the frontline without a complete set of the necessary modifications, so wartime production pressures also played some part.

Re the model: one point to bear in mind is to check the markings against the weapons: squadrons were dedicated to bombs or rockets. Aircraft with the big tail were preferentially gathered into the bomber units (supposedly to permit carriage of the 2x1000lb bombs, but this is unconfirmed) but this is not a hard-and-fast rule, and obviously changed with time.

Edited May 21, 2008 by Graham Boak

[AnonymousA667]

The weights in the tailplane were to change the flutter characteristics.

Are we not talking about the elevator mass balance? Most control surfaces have a tendency to flutter unless there is a balance weight ahead of the hinge line to dampen it out. The Bentley drawings show the Tiffie elevator balance on an arm within the rear fuselage.

peebeep

[Test Graham]

Yes, we are. It was this arm that failed in fatigue, due to vibration from the engine, and was replaced by some other mod involving weights somewhere else - I've not seen drawings of this. Chris Thomas has looked for this but there are a number of modifications in this area and I don't think he's found it possible to disentangle the key storyline, as it were. The main references all over-simplify and thus conceal the sequence of events: Beamont is perhaps the best on the subject, as you might expect.

It is perhaps open to discussion whether the vibration from the engine caused the elevator to vibrate in a mode (post-failure) that inspired flutter - I don't think so but it may be true. I found aeroelastics far too difficult....perhaps I'd have concentrated harder had I known I'd be posting on the subject decades later! However, the lecturer used the Spitfire wing redesign as his example rather than Typhoon tailplanes, and that was mainly aileron reversal and wing divergence, rather than flutter. I don't recall which example he used for flutter, other than it wasn't the Typhoon.

[Edgar]

According to the AVM, the flutter problem had been eradicated by the use of the 4-blade prop, plus the Tempest tailplane, but he said that the reintroduction, of the 3-blade prop, had necessitated the fitting of 10lb weights in the tailplane tips, and the 70 aircraft, then in storage, were being modified at the rate of 10 per day. It rather sounds as if the flutter was in the tailplane, not the elevators.

According to Francis K.Mason, Camm sent his paperwork, to him, so he might have the answer; unfortunately (allegedly) requests, for help, can get a mite expensive.

Edgar

Edited May 21, 2008 by Edgar

[Test Graham]

AVM? Air Vice Marshal?

The 3-blade prop was not re-introduced so much as renewed: it never went away completely. The proportion was reducing as the later aircraft arrived, but losses were such as to require the collection of old Typhoons from OCUs, MUs etc and reworking them. Mainly this meant fitting the bubble canopy and the latest mods, surely a fresh engine, but does not seem to have included the 4-blade prop and the big tailplane. These were all small tailplane/three-blade prop aircraft, as seen in photographs, and as such would indeed require attention to flutter.

Until someone comes up with a photo of an in-service early serialled-aircraft with the Tempest tail, which would require some explaining.

However, there's no reason not to fit the earlier engine/prop combination into a late-serialled airfame, other than configuration control and a certain drop in thrust. There's not a lot of point, but it is the other combination which gave dodgy handling. Note that this is not just a prop change: the engine comes with the appropriate number of splines on the crankshaft so this is an engine change too. I've seen it said that this was the only difference between the two engines - but Sabre variants do not appear to be well defined in Typhoon/Tempest books.

As I recall, it is the movement of a control surface that sets up the resonance, so changes to either the control or the fixed surface could change the aerodynamic/structural interactions.

Edited May 21, 2008 by Graham Boak

[Bo Roberts]

More Typhoon questions. The instructions call for the paint under the bubble behind the head rest to be gray-green, but a photo I have from above, has it a very dark color that I'd guess to be black.

One more; the light behind the head rest. Is that a real light ?? If so, I bet it caused alot of reflections inside at nite, huh??

What say you experts??

Bo Roberts

[Edgar]

Delete the light; it was on the prototype only. Every reference, that I've seen, says that the area covered by the hood, when closed, was black.

Edgar

[Bo Roberts]

Delete the light; it was on the prototype only. Every reference, that I've seen, says that the area covered by the hood, when closed, was black.

Edgar

Yo da Man, Edgar!! That's what I was planning to do and now you've confirmed it!! With a lite inside the canopy, it'd be darn hard to see outta it at nite!! Reflections everywhere!!

Again, thanks Edgar!!

Bo Roberts

[Edgar]

There were thoughts of using the Typhoon as a nightfighter, with one actually being fitted with radar (now there's a conversion, for you.)

We've been looking at the RAF Museum's example, and it appears that the tail lights might have had the same configuration as nightfighters & intruders (even bombers, apparently.) One glass is clear, but the other is a very opaque "white," and we're wondering if that was a "resin" lamp, which only reacted to an infra-red enquiry. Although the Typhoon was a daylight aircraft, they might have needed that protection, if they were returning, after dark, during the winter of 44/45. Of course, the plastic might be damaged, by age, and I'm sending you on a wild-goose chase (again!)

Edgar