Constant speed versus two speed props

[Melbatoast]

This was brought up in another thread, but I'd like to bring it up separately. Is there any chance we could equip the majority of British airplanes with the constant speed propellers? By the time of the Battle most all of them were set up as such. The 3d models show constant speed props, too.

As well, if we could get the designations Ia and Ib removed, that would be great. They're spurious in the context of the game - deHavilland and Rotol would be good alternatives.

[Hylander_1715]

Actually during the Battle, the two speed prop pitch was standard, as the RAF had been using the Watts two blade props that had no pitch variation. The two speed pitch control was something fairly new, as many a hurricane were still using the two blade fixed pitch props in France during the Phoney War and the Blitz. If memory serves correct, it was in the spring of 41 that the constant speed prop pitch became available to the RAF squadrons.

[BPNZ]

Hi Hylander,

That's not quite correct.

For the Spitfire, the two-pitch three blade prop was standard from the 78th Spit produced only until the spring of 1940. From that time new production Spits had the constant speed prop as standard and kits were being prepared to retro-fit the existing Spits in the field. This was done by deHavilland with assistance by the local ground crews. I have a document at work detailing the process and giving the time the work was completed, which I think was during July 1940. Therefore except for the occassional plane nearly all the Spitfires in BoB would have been fitted with this prop.

Proof of the approximate timing of the C/S prop being available can be given by it being tested on the Spit N3171 mid-March 1940.

I have fewer details on the Hurricane however again they would have been fitted on new aircraft around the same time with existing aircraft upgraded as time permitted. As there were many more Hurricanes than Sptifires this process took longer with the last Hurricanes not upgraded until I think September or October. Hurricanes usually received Rotol c/s props whereas Spitfires usually received deHavilland ones.

I don't doubt there were were two blade Hurricanes used in the Battle of France as there would still have been many of them then. Also Dowding would have probably preferred to keep the better equipped planes for Home Defence.

BPNZ

[spinner]

Melbatoast, Hylander, I missed your new post, duh, sorry, and addressed some comments to you and Hylander in Bucic's thread, windmilling props. Good to start a new one on this. My cheat is to modify the 'PropType' line near the top of the Spitfire 1A and Hurricane 1A.acm files to {constspeed. . .} So now all my Spits and Hurris are constant speed - probably not entirely accurate but more accurate anyway. BPNZ clearly has the dope on the chain of events. Apparently the work was so rushed a de Havilland clerk said "We shall probably never be paid for this work" and a colleague replied, "if we don't do it we may never live to be paid for anything". Desperate times!

Spinner.

[Melbatoast]

Melbatoast, Hylander, I missed your new post, duh, sorry, and addressed some comments to you and Hylander in Bucic's thread, windmilling props. Good to start a new one on this. My cheat is to modify the 'PropType' line near the top of the Spitfire 1A and Hurricane 1A.acm files to {constspeed. . .} So now all my Spits and Hurris are constant speed - probably not entirely accurate but more accurate anyway. BPNZ clearly has the dope on the chain of events. Apparently the work was so rushed a de Havilland clerk said "We shall probably never be paid for this work" and a colleague replied, "if we don't do it we may never live to be paid for anything". Desperate times!

Spinner.

Ah! That's a quick fix, and I'll do it.

Hi Hylander,

I don't doubt there were were two blade Hurricanes used in the Battle of France as there would still have been many of them then. Also Dowding would have probably preferred to keep the better equipped planes for Home Defence.

BPNZ

This is true - Paul Richey talks about his Hurricane having a two blade prop during the BoF in Fighter Pilot, and all the disadvantages of it. Many also had fabric wings.

[gleed]

Hi guys:

You’re right Melbatoast that most of the British fighters in front line service were equipped with constant speed propellers by the start of the Battle of Britain. I don’t think there would be a whole heck of a lot of difference in performance between de Haviland and Rotol equipped aircraft though. My understanding is in agreement with BPNZ in that as a rule the Hurricanes received the Rotols while the Spitfires got the De Haviland CSP but there certainly were exceptions. New production Spitfire I’s were equipped with Rotol constant speed propellers starting in November 1939. N.3171, the aircraft tested by A &AEE at Boscombe Down, was delivered on 13 November 39 (the trials report is dated 19 March 1940) . No. 54 squadron was fully equipped with “Rotol Spitfires” in December 1939. The crash retrofit program converting deHaviland 2 pitch propellers into constant speed types is widely written about, well known, and began in June 1940. Spitfire II’s were also fitted with the Rotol CSP. Deliveries of Spitfire II’s equipped with Rotol CSPs to active units began in August 1940.

Apparently new production Hurricanes were being shipped with Rotol constant speed props during the Battle of France. FWIW Paul Richey writes in his book about “flying a new aeroplane with a Rotol constant-speed prop” while in France (Fighter Pilot, page 93). So does Ian Gleed in his book (Arise to Conquer, page 62). Morgan & Shacklady wrote in Spitfire the History, page 54: “By 16 August every Spitfire and Hurricane had been converted, including those in store. Hough & Richards in The Battle of Britain, page 84, also discuss Hurricanes in France being fitted with Rotols “by manufacturers’ parties flying from England to do the work”.

[gleed]

Hiyas:

More information on the Hurricane Rotol constant speed prop story has turned up:

151 Operations Record Book, 15 May 1940 "The squadron can now put up 12 Rotol Hurricanes if required." From the Hurricane Mk I Performance page.

[gleed]

Hello:

Here’s some more information on Spitfire Constant Speed Propellers .

No. 19 Squadron received their first Spitfire I equipped with a Rotol Constant Speed Propeller on 1 November 1939.



No. 19 Squadron Operations Record Book, November 1939.

As mentioned earlier No. 54 Squadron fully converted to Spitfires with Constant Speed Propellers in December.



No. 54 Squadron Operations Record Book, December 1939.

All material from: Spitfire Mk. I versus Me 109 E Performance Comparison

Taking on charge CSP equipped Spitfires in November 1939 strikes me as quite a bit earlier than generally thought.

I wonder if Hurricanes equipped with Constant Speed Propellers also reached operational units as early as 1939. Does any one know? As mentioned above we know from Hurricane I Performance that Hurricanes were delivered with Constant Speed Propellers no later than April 1940 and aircraft so equipped were used during the Battle of France, well before the Battle of Britain.

No. 151 Operations Book, April 1940

There’s also some more links on that site about de Havilland props being retrofitted to constant speed in June 1940 before the Battle of Britain started.

No. 611 Squadron Operations Record Book
No. 609 Squadron Operations Record Book
No. 74 Squadron Operations Record Book

Interesting!

[PV]

Starting 26th June and converting one aircraft per day per airfield, one would expect about 30-50% complete by the start of the sim @ July 11th, and convertion completed around the 1st of august.

[gleed]

Hi PV:

Your numbers manipulations are lost on me but the information I shared regarding re-equipment of fighters with constant speed props appears lost on you so I suppose we are talking past each other? You appear to be basing your calculations on percentage of aircraft at an airfield converted to constant speed props rather than percentage of aircraft within a unit converted to CSP? (How many units per field or aircraft per unit is unspecified). Is there an archival or book source for this 30-50% estimate by 11 July?

Let’s look a little closer. Is it clearly understood that units were converting to constant speed airscrews in 1939? If not, please refer again to 19 Squadron ORB and 54 Squadron ORB. Note also that units were equipping with CSP equipped aircraft prior to the German invasion of France and during the subsequent battle; please refer again to
Gleed, Richey and 151 Operations Record Book, 15 May 1940



The part of the story that has been completely overlooked and apparently forgotten to history is that new production aircraft were delivered with Rotol constant speed props well before Dunkirk and the Battle of France, let alone the Battle of Britain. Perhaps the DeHaviland retrofit program is more dramatic? Regarding the DH conversion program, Woods & Dempster note that “It was estimated that ten days would be required to convert a squadron”. 609 Squadron ORB noted that one Spitfire was converted on 26 June and “The remainder of the aircraft will be converted within a period of 8 days” which would mean full conversion prior to the 10 July start date of the Battle of Britain (Of course they may have already had some new production aircraft already equipped with Rotol CSPs on charge). 611 Squadron ORB notes work was started on converting DH props to constant speed on 28 June and it was expected to complete one aircraft per day, which would have a full formation of 12 converted prior to the Battle of Britain. David Ross wrote that 603 Squadron was re-equipped “in a matter of days” with Rotol or DH CSPs prior to 10 July.

The Narrow Margin and Spitfire the History talk of 65 Squadron converting DH propeller equipped Spitfires in June. Documentation already presented here shows 74 converting in June, how many we don’t know. We know 54 Squadron was re-equipped with CSP Spitfires in December 1939. 54, 65, and 74 Squadrons were all based at Hornchurch at the start of the Battle of Britain on 10 July. Hornchurch was the premiere Spitfire station in 11 Group during the Battle of Britain. It’s quite clear that Hornchuch’s fighting force of Spitfires were all equipped with constant speed props by commencement of the Battle of Britain. No doubt there were some operational and maintenance units somewhere in the UK still in the process of converting all their DH equipped fighters by the start of the Battle of Britain but lets get a proper perspective and understand clearly the representative condition of those fighter aircraft engaged in battle throughout the Battle. Primary archival documentation and cited book references should be our guide in determining the facts.

[PV]

You dump a whole lot more words into the pot, but you don't say anything different. Conversions start 26th to 28th June, one plane per day, it reads to me like they have one crew from DH per airfield, and each airfield has at least one sqn of 12 planes, most more, so they're not going to be done by 11 July. They will surely be done by 1st august. Maybe they're done by 16th July, but how can we know from what you've posted here, as we have some 32 sqns to consider in the game, or was it 64.

[gleed]

Hello. Further information concerning the equipping of Hurricanes with constant speed props well before the Battle of Britain has surfaced. No 1 Squadron was based in France in April 1940 when they received their first aircraft equipped with constant speed prop followed by others in early May before the Germans even invaded France.

1 Sqdn. Operations Record Book, 18 April 1940: "A new Hurricane was delivered to the Squadron, equipped with a constant speed airscrew and was flown by the C.O. and other pilots, all of whom were greatly pleased with it's superior performance."



1 Sqdn. Operations Record Book, 2 May 1940: "Five machines flew to Amiens and four were exchanged for the new constant speed airscrew Hurricanes."



Interestingly, these entries in No. 1 Squadron Operations Record Book corroborate Richey’s account of 15 May where he notes "I was flying a new aeroplane with a Rotol constant-speed prop..." while with No. 1 Squadron in France.

From: Hurricane Mk I Performance

[gleed]

Hello: Please find below additional information regarding constant speed propellers equipping operational Hurricanes well before the Battle of Britain, in this case as with No. 1 Squadron shown above, during the Battle of France. From The Hawker Hurricane by Francis K. Mason, pg 48.

"No. 32 (F) Squadron, based at Biggin Hill and flying Hurricanes with Rotol propellers, went into action on 19th May over Cambrai…"



From: Hurricane Mk I Performance

Melbatoast had it right with the intial post in this thread: "Is there any chance we could equip the majority of British airplanes with the constant speed propellers? By the time of the Battle most all of them were set up as such."

Indeed!

[gleed]

Here’s a nice photo of a 32 Squadron Hurricane with Rotol constant speed propeller at Hawkinge, 29 July 1940. As related above Mason wrote that 32 Squadron was equipped with constant speed props when they went into action over France during May 1940.



501 Squadron Hurricane with Rotol constant speed propeller at Anglure, France during May 1940.

[gleed]

Hiyas:

Here’s further material related to constant speed propeller equipped Hurricanes from the period prior to the Battle of Britain; taken from Hugh Halliday’s 242 Squadron, the Canadian Years:

Rotol constant speed propellers had been fitted to the Hurricanes in Early June, replacing the two-position propellers of earlier models.

Here’s a nice photograph of a 242 Squadron Hurricane equipped with a Rotol constant speed propeller taken while the unit was based in France. The pre Battle of Britain camouflage scheme with the black and white under wing patterning helps place the date of the photograph at around the time of the unit’s service in France in June 1940.



I can recommend Halliday’s book – pretty good!