2x Spitfire Vc trop propellor identification help needed

[Edgar]

Supermarine, themselves, only list the hydromatic (together with Rotol C/S and deH bracket) as being used on the Va, Vb, Vc, and Seafire I.

[gingerbob]

OK, I've done some homework. I've got numerous other comments about props, but this should give some idea:

4A AOCinC FC (Sholto-Douglas) to USofS (AM ACAS(T)) (FC/S.23274) 23/4/41

c) I have been informed that the Rotol airscrew which was to be fitted to the Spitfire V is not available and that an obsolete type of DH airscrew is to be used instead. This airscrew freezes up at high altitudes and has been the cause of damage to three valuable M45 engines. I request the early provision of the Mod parts necessary to prevent this freezing up, both for retro action and for the production line. I trust that the more modern type of Rotol airscrew will become available again at an early date.

11A Airscrew Situation for Spitfire V a/c (Beardsworth- CTO) 16/5/41

4. I enquired whether the bombers were having the Rotol and he said they were because they need the wider range of movement of 35º for taking off. I explained that the Spitfire Vs also required the wider range too to allow both a good takeoff and to keep the engine RPM down in a fast dive. In reply he said that the Boscombe report stated that the rpm in a steep dive did not go above approx. 3500 with the DH airscrew and that this is permissible for a short time. My answer to this was that 3500 rpm may be all right at heights up to 30,000' but that above that height aeration in the oil tank became an important factor in the life of the engine bearings, and so for that reason I wanted to keep the maximum rpm down to as near 3000 rpm as possible- the Rotol keeps the rpm down to 3100 rpm and so reduces to a minimum the aeration in the oil tank.

5. There is no doubt that the airscrew production people are in a jam over the wooden airscrew blades position- they say they have plenty of hubs- the truth is they did not allow sufficiently for the "repair of a/c" requirements which are 60% of the production line figure and they have been affected too by enemy action.

6. We investigated whether we could remove the Rotol off the Hurricane I in ASUs and came to the conclusion, for various reasons, that the small number obtainable was not worth the complication of removal of controls, piping, etc. I have learnt, though, this morning, from No.41 Group that they are removing 100 more this month, and a further 80 next month. I have passed this info on to Bulman this morning and he is checking the position up forthwith. This number of Rotols might be sufficient to keep the Spitfire production line going until the Rotols manage to achieve increased productive capacity.

7. In October of this year the Spit V should be equipped with a new DH Hydromatic airscrew which should outclass the present Rotol but that does not help us over the intervening period.

8. In conclusion there can be no possible doubt in anybody's mind that the Spitfire V a/c are handicapped with the obsolete 20º range DH airscrew and that we require the Rotol with its 35º range of movement as soon as production permits.

18A AOCinC FC to USofS ACAS(T) 23/5/41 (draft- 19A sent copy, essentially the same)

Spitfire V aircraft = Rotol airscrews

concern re fitting DH 20º.

3. The Spitfire V aircraft is able to operate in the region of 38,000' where there is considerable aeration in the oil tank due to the low atmospheric pressure. This oil aeration is intensified by high rpm, which in a fast dive with the DH prop may reach up to 3500 rpm instead of the 3100 rpm with the Rotol airscrew. serious, may affect life of main bearings.

4. told 300 Rotol being removed Hurricane I for overseas, where metal DH more suitable.

5. I request investigate equipping Spit V with Rotol instead of DH.

20A Bulman (DEDP to AOCinC FC 20/5/41 [s/b 26/5?]

3600 rpm is the declared and permitted max diving speed of the Merlin and neither RR nor ourselves know of any reason to cut it back.

tests indicate DH OK.

setting 52º on Mk.II, 54º on Mk.V

...

In any case the production situation precludes the possibility of providing 100% Rotol airscrews on the Spitfire V. We are providing for some 60% Rotol on these a/c and are pressing on with the DH airscrew with wider pitch range to come into production towards the end of this year. By thus running two lines of supply, Rotol and DH on the same type of a/c, we have the valuable safeguard of duplication against the effect of enemy action on the one or other manufacturing source.

It was suggested take Rotols off Hurricane. The blades of these allocated as spares. The consumption of wooden blades, due to crashes is very much higher than anyone foresaw, and as result we are having to step up our wooden blade pdn by an additional 60% over original estimates; such increase in capacity must necessarily take several months to mature.

O7 to DDAP1, etc 26/5/42 (O.3326)

48 Mk.Vb Spits required packed for new special destination not connected with any previous special commitments. A/C are to be packed on highest priority. Request 53 wing HQ signal at which packing depot work will be undertaken. These to be trop fitted Merlin 46 VHF (TR.1133), IFF, Long range 90 gallon tanks and Rotol (RX 5/10) props. TR9D wireless and 2 30 gal jettison tanks to be included in packing case of each a/c. Crystals will be supplied on arrival at overseas destination. A/C are required packed by 16/6/42.

O7 to DDAP1 etc 29/5/42 (O.4196)

The qty 48 Spits for new special destination must now be Mk.Vc. Other requirements identical except prop will by Hydromatic instead of Rotol.

[These are the ones that mostly got shanghaied to Africa, but it illustrates the intention. There is talk in connection that some with the older prop should be available for other destinations.]

? E.34 to O.7 28/7/42

re yours 14, 21/7/42 it is noted that no provision has been made for the fitment of the DH 5/39 propeller to production line a/c after 6/42. DH is no longer producing this type, but there are a large quantity awaiting repair and in the next 2 months (Aug/Sept) 100 will be available per month for fitment to the production line.

Will you please take up with MAP the question of how these can best be utilised.

These should be used if possible to ease the commitment for the DH Hydromatic which the production dept have informed us may not reach the output programmed due to the large demands for spare blades which have to be sent overseas.

Your early reply is requested stating the firms to which these Bracket Type props are to be sent.

I'm not sure what relevance (if any) this might have, but, on 31-7-42, a nameless Squadron Leader aka "O.7" reported, to M.A.P. A.P.1.C, that, over the following two months. production of Hydromatic propellors would be insufficient to meet the needs of Vb & Vc "as a considerable number of these propellors has to be sent overseas as spares."

He then states that an extra-large quantity (100 p.m.) of DH/5/39 propellors will become available (some from repair) for fitting to production aircraft, but, since DH/5/39 were not to be installed on aircraft held for Fighter Command Squadrons, he asked that they should be fitted only on tropicalised aircraft, and that "temperate aircraft receive the priority of available hydromatic propellors."

Edgar

In the actions over Darwin, failure of the CSU in the dive would cause the engine to rapidly increase to 4,000 or even 4,200 rpm, the resulting failures being those of the oil seals through overheating and pressure rather than valve/piston contact. This caused oil to spray back over the canopy and glycol to escape into the engine with the result that white smoke poured from the exhausts, and the oil pressure dropped dramatically. Pilots who managed to "catch" the engine before reaching these speeds did manage to recover and even re-engage.

Postagram DDO(A) to various 18/4/43

Prep and Mod of Spits for overseas

re S.85222/O7b of 18/2/43, following amended instructions:

5. Arrangements have been made with MAP (DDAP1) for those two mods to be omitted from the first 40 Mk.V at CB each month; these to be allocated by 41 Gp to India and Oz; Oz quota will be fitted with Hydromatic props.

Edited April 15, 2013 by gingerbob

[Work In Progress]

Ah, thanks, GingerBob, that para 4 confirms exactly what I suspected. Very interesting.

[tonyot]

Would the propeller problems with RAAF Spit Vc`s explain why many of them later had oil collectors fitted behind the spinner, just like those found on Hurricane`s?

Cheers

Tony O

[Test Graham]

John: There is a photo of a Spitfire without its spinner on p135 of Darwin's Spitfires. It looks like a standard Hamilton hub to me, but were the Hydromatics visibly different? Cooper discusses reasons for the failures on p133 to 136, but refers to the DH Hydromatic propeller. There is no direct indication that he is aware of differences between this and the original DH version - there is an implication of this in his reference to identical propellers being used over Malta, where both types of DH propeller were used.

Bob: The reference to 48 Spitfires for a special destination must be Malta, as shown by the 90gall ferry tanks. The change from Rotol to Hydromatic is consistent with the story told of early trials from HMS Furious and the resulting demand for the Hydromatics. The first delivery of Spitfires intended for Australia were "hijacked mid-voyage by the RAF's Middle East Command" but if these were the same individuals the total number is different (42 vs 48) . The first in Australia arrivals were in October/November. A quick look in STH suggests the first as BS158 FF 16.6.42, shipping on 30/7, Australia 16.10.42. This seems to fall in line with the timing of the correspondence quoted above, so will these aircraft have had the earlier and faulty DH prop? The implication of the correspondence (to me) is that at some convenient stage at least the later shipments will have had the Hydromatic.

Cooper states that DH specialists came out in July 1943, too late for the daylight raiding campaign. He says "they had 'an exchange of views' with the pilots of 54 Sq" - oh to be a fly on that tent wall!

Surely, had it been a matter of early DH props having a failing that was cured by the Hydromatic, then this would have been made clear at some stage in Australia and made its way into the records. That this does not seem to have happened makes me wonder whether the Hydromatic propeller, as used on the Mk.Vc(Trop), didn't cure the fault.

I understand that there is no difference between the original spinner and that used with the Hydromatic, but am I right? The photographs clearly show the original spinner, but this may be hiding a different CSU.

Tony: On Rotol or on DH? On the Hurricane this was limited to the Rotol. I must admit I'm not aware of the Australian mod. As far as I know there is no such mod on Mk.Vs in any other theatre, but it might be worth a look as it could perhaps be easily missed. There's no suggestion in Cooper that the Darwin period saw any oil leaks other than in the case of dramatic failure of the engine.

[John Aero]

I now plead to change my opinion I have just been sent a couple of photos of the Hydromatic Vc installation by a kind reader and I am now certain that the props shown are DH Hydromatic .

Cheers

John

[Test Graham]

Excuse me, John, can I confirm: you are saying that the Hydromatic spinner is longer than the original?

[John Aero]

Graham, I would say yes, certainly than the bracket type DH props IMO.

John

[gingerbob]

The first delivery of Spitfires intended for Australia were "hijacked mid-voyage by the RAF's Middle East Command" but if these were the same individuals the total number is different (42 vs 48) .

Here's a little more detail, and the reference to the other group of 32 may be of interest to you (i.e. you may know exactly which group it refers to, which I don't without figuring it out.) 42 were loaded on one ship, the other 6 were on a different ship- as I recall, the same ship that was carrying the personnel.

These two came from:

Folder O.Ops 2/10 "Spitfires Australia" 5/42-4/44

O7 to DDAP1, etc 26/5/42 (O.3326)

48 Mk.Vb Spits required packed for new special destination not connected with any previous special commitments [emphasis added]. A/C are to be packed on highest priority. Request 53 wing HQ signal at which packing depot work will be undertaken. These to be trop fitted Merlin 46 VHF (TR.1133), IFF, Long range 90 gallon tanks and Rotol (RX 5/10) props. TR9D wireless and 2 30 gal jettison tanks to be included in packing case of each a/c. Crystals will be supplied on arrival at overseas destination. A/C are required packed by 16/6/42.

Qty 15 similar Trop Spits will be required each month starting in July. To ensure supply to beginning of '43 last 75 trop Spit V's due off production in Sept/Oct should be earmarked against Sept/Oct quotas of 15 with balance of 45 covering Nov-Jan quotas.

O7 to DDAP1 etc 29/5/42 (O.4196)

The qty 48 Spits for new special destination must now be Mk.Vc. Other requirements identical except prop will by Hydromatic instead of Rotol.

To meet this requirement the 32 Vc Spits allocated by O.2031 of 21/5/42 for a different special destination may now be replaced in whole or in part by Vb with either M45 or M46. Anticipated that 19 will be so substituted as up to 13 Vc's with CAM (5/39) type props should be available. ...

DDAP1 to O7 30/5/42 (AP795)

... the commitment of 32 will be made up of 19 Vb and 13 Vc. 13 Vc will be fitted with 5/39 props. Endeavour being made to fit the 19 Vb also with this prop. This may mean that there will not be time to air test guns on these 19.

~~~~~~

I don't know anything about the spinner question- I've never given it careful study (I'll have to put it on the to-do list, unless Edgar presents us with an answer), and if I've seen any illuminating references in the documents it didn't stick in my memory!

bob

p.s. I did come across one minor reference to the carrier takeoff question, and I'm pretty sure I have more detail somewhere, but I'm not sure where. I'll have a quick look...

[tonyot]

Tony: On Rotol or on DH? On the Hurricane this was limited to the Rotol. I must admit I'm not aware of the Australian mod. As far as I know there is no such mod on Mk.Vs in any other theatre, but it might be worth a look as it could perhaps be easily missed. There's no suggestion in Cooper that the Darwin period saw any oil leaks other than in the case of dramatic failure of the engine.

Hiya Graham,

Sorry to disagree with you here and to digress from the thread but quite a few Hurricane Mk.I`s (and Canadian Mk.X`s) that were fitted with DH props had the oil collector ring fitted and it was a regular fitting on wartime Sea Hurricane Mk.Ib`s which were all fitted with DH props. I have read that the DH prop was fitted to Sea Hurricanes for balance reasons due to the arrester hook but as the Shuttleworth Collections aircraft flies quite merrily with a Rotol, maybe it was due to carrier performance, as mentioned earlier regarding Spitfire V use of the DH/ Hamilton Standard prop.

Re the use of similar oil collector rings on RAAF Spitfire Mk.Vc`s, it was generally after the Darwin period, mainly in second line service with fighter and gunnery schools although 79 Sqn RAAF (UP codes) did operate some as did 85 Sqn (SH codes).

All the best

Tony O

Edited April 16, 2013 by tonyot

[John Aero]

I've just been doing a little reading on the props and the early controllable DH types used oil pressure to move into fine pitch and the counterweights and centrifugal force to return to coarse pitch. The Hydromatic used oil pressure for both operations as did the Rotol but with differing mechanisms.

John

[Test Graham]

Hi Tony: no need to be sorry, I was referring to seeing this mod on Spitfires. The Shuttleworth SeaH has some dummy parts which helps to maintain the cg - it was Shuttleworth's Owen Dinsdale who first alerted me to the reason for DH props on SH. I don't know why this mod was maintained onto the Mk.II with its different Rotol prop, whereas the Spitfire never needed one. It may be because the Spitfire has a wider nose and any leaked oil disappeared inside rather than spilling out.

The two ships carrying the first deliveries of Spitfires to Australia were first the Eurybates and secondly the Hoperidge, but SH lists at least nine on the Eurybates, so the loading must have been altered. I have to say that these Spitfires had the short spinners, so the matter is still confused.

Deliveries to Malta in the summer of 1942 were almost entirely Mk.Vb, including all of Bellows (ie part of the more famous Operation Pedestal August 11/12)) from Glasgow on Furious. I can link 36 airframes to this delivery but at least three of them have doubtful dates. Malta:The Spitfire year quotes 38. Deliveries sized at 32 are probably being shipped to Gibraltar for Eagle or (later) Furious. The mixed delivery is Baritone, which followed Bellows, and my list does indeed show it with 13 Mk.VcTrop (phew!).

Edited April 16, 2013 by Graham Boak

[Work In Progress]

It may be because the Spitfire has a wider nose and any leaked oil disappeared inside rather than spilling out.

I believe that to be the case.

[gingerbob]

Yes, to be "vented overboard" at the lowest point, thus one possible reason for the famously dirty bellies? Wait a minute, I saw something like that...

"It may be because the Spitfire has a wider nose and any leaked oil disappeared inside rather than spilling out."

25A Bulman to FC 25/6/41

arrangements have been made as you suggest to test the Schwarz bladed Rotol hub on a Spitfire V.

ground clearance will be reduced by 1/2" and the spinner will cause a break in the Spitfire cowling lines by a gap of 1" radial and 1/2" fore and aft which may well produce unpleasant effects in sucking oil out of the engine, and may be, on performance.

The use of the Jablo bladed hub is out of the question in that the diameter is 11' and would entail clipping of the tips at prohibitive cost in productive hours.

To fit the Spitfire DH hub in the Hurricane would entail new spinners in that the former would obviously foul the engine cowling.

~~~~~~

Is the Jablo the Hurri II prop?

Edited April 16, 2013 by gingerbob

[Test Graham]

The Merlin leaked much greater volumes of oil than were contained in the prop system. However, staying with the digression (but hopefully not for long) I can see why the early Rotol required an oil ring on the Hurricane, as it overlapped the nose. This wasn't true about the later one on final production Mk.Is and all later marks.

[John Aero]

FWIW I've just realised why the Rotol props needed more spinner clearance ( forward length) than the early DH bracket ones. The Rotol prop pitch change cylinder moves forwards and back and the internal piston is fixed, unlike the later Hydromatic in which the cylinder dome is fixed and the internal piston moves. I now think that the Spits fitted with Hydromatics possibly required a slightly longer spinner forward of the prop for clearance of the piston dome. The metal DH blades often mistaken for early Rotol wooden blades are indeed broader than the old bracket metal ones.

John

Edited for clarity.

[gingerbob]

Excellent John.

(I meant "a contributing factor" rather than "one sole cause".)

So, interpreting what I added to my post above, the Spit spinner is longer aft of the prop disc than the Hurri one, but I haven't quite sorted which prop and spinner shape is being compared to which in this Schwartz/Jablo Hurri/Spit idea.

[John Aero]

The spinners won't be longer behind the prop as they still have to fit the shaft and cowl clearance. The 11' Jablo will be the Hurricane prop hence the reference to machining the tips. The prop it's self would fit the Spit but the pointed spinner would be smaller and the blade dia too great. The opposite is that early Rotol Jablo/Swartz prop off the Spit with the bulbous spinner was too big for the Hurricane cowl but they were still fitted to B of B Hurricanes.

John

[Test Graham]

Tony: I've spotted the small oil spill plate on some of the later Aussie Mk.Vs, in the original Kookburra booklet. I can't find it anywhere else, nor think of any other reason for it to be seen on DH props, other than this failure case of the CSU.

re looking for other sources: Spitfires over the Arakan shows Rotol blades. However, Brian Cauchi's new book has lots of photos of Malta Mk.Vs. Some of them do have rather more pointy tips to their DH spinners than others, and the blunter ones do tend to be the earlier ones. The captions and artwork are far from definitive on this, showing some with pointy spinners as earlier delivered aircraft. Or at least implying that - in many views it is impossible to be certain of the serial. Switching to Cooper, the Darwin ones do seem to have these pointier tips, although not particularly longer in length. This is generally backed up by the more numerous ones in the Kookaburra, but .... they still do look stubby. I can see why changes to the dome of the CSU might require a longer spinner, but not a pointier one.

It does occur to me that forming a spinner is a particular skill, and could be open to some variation. The rounder tips/pointier tips may just be that......perhaps.

On balance, it seems likeliest that Australia did get the Hydromatic prop, but in that case why didn't it show similar problems elsewhere in its world-wide use? Possibly this is linked to the tactical errors of the leaders at Darwin, with their insistence on cumbersome Wing formations and delays at altitude before attacking? But that would require another thread.

[elger]

and there I was thinking I was asking a simple question :-)

so the propeller below is a.... ??

[John Aero]

DH licence built Hamilton Standard Hydromatic metal blade prop with the pitch change cylinder removed .

John

[greatgonzo]

early Rotol Jablo/Swartz prop off the Spit with the bulbous spinner

John

Weren't the MkII Spitfire Rotol blades made of aluminium?

[Test Graham]

Magnesium is how they are described, probably an alloy of some kind? But slim metal blades, yes. A range of different blades were tested for the Mk.II, see Spitfire The History p97 onwards. However, the broader blades on later Rotol Mk.Vs (some vey early ones had Mk.II spinners and propellers, given the problems with the DH prop) were made of wood, or rather resin impregnated compressed wood (Jablo). I believe Jablo is the name of the company producing these blades in this material but it may also be a trade name for the material itself.

John: how are you deciding that's a Hydromatic? From the shape of the blades?

[John Aero]

Some early Rotol props used Magnesium blades. As you can see the identification of Spit props is a nightmare and intensive tests on various props were carried out on Spitfires and it appears that the end result was that DH were to concentrate of metal props but not to use Magnesium and Rotol were to concentrate on Wood and Jablo props. As we have seen identification by sight is very difficult and even more so by at least 17 different props in varying materials tested on Spitfire II's.

John

Graham , By the Hub body design.

John

[John Aero]

By the way the prop hubs shown on page 53 of the M and S book, the lower one shown as a Hydromatic,isn't. It's a dismantled bracket type.

John