Michael Hope
Airman 1st Class
- 249
- Jun 28, 2016
Sorry for the late response, I do not have any access to DeHavilland branded propellers documents.
Propeller Identity - Help
- Thread starter Clevely15
- Start date
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MiTasol
1st Lieutenant
Bother. I think you were the best hope for solving this one.
Could you advise the distance from the centreline of the prop shaft to the base of the blade that the OP has so that all can know the actual diameter of that propeller?
Could you advise the distance from the centreline of the prop shaft to the base of the blade that the OP has so that all can know the actual diameter of that propeller?
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Michael Hope
Airman 1st Class
- 249
- Jun 28, 2016
On a Hamilton Standard 23E50/23EX, the bottom of the blade butt would be 2.813 inches, less the thickness of the blade bushing. I assume that the DeHavilland propeller would be similar.
MiTasol
1st Lieutenant
Thanks Michael
Most dH and HS parts were totally interchangeable at that stage.
If we call the 2.8 inches as three inches (given any fraction of an inch was called a full inch in the official diameter) then add 6'4'' that gives a radius of 6'7'' and prop diameter of 13'2''.
Now all we need is a list of Brit aircraft from 1941 with the diameter of their props. Unfortunately I do not have a copy of the 1941 Janes but I will see if I can track one down.
Most dH and HS parts were totally interchangeable at that stage.
If we call the 2.8 inches as three inches (given any fraction of an inch was called a full inch in the official diameter) then add 6'4'' that gives a radius of 6'7'' and prop diameter of 13'2''.
Now all we need is a list of Brit aircraft from 1941 with the diameter of their props. Unfortunately I do not have a copy of the 1941 Janes but I will see if I can track one down.
Geoffrey Sinclair
Staff Sergeant
- 989
- Sep 30, 2021
Passing a message on,
Firstly Mosquito and Lancaster blades. These are all hydromatics :
'I had a look through sections of my files. This is not a complete listing of propeller types but a shortened version (i.e. to save my time, full designation not always provided) of blade types used with various Mk's of Mosquito:
Mk's I/II/III/V - Merlin 21- P4551212 (original Mosquito 'narrow' blade 12ft 0ins dia.)
B.XVI –Merlin 72/73/76/77 –DP454612
B.XVI - Merlin 76/77/113/114 -6519A-12
P.R.I/FII/BIV/NFXII- Merlin 21 or 23 – DP4551212
P.R .I/IV/VIII- Merlin 21/23/72 –P4551212
P.R. VII– Merlin 72- DP4551212
P.R. XVI –Merlin 72/73/-P4551212
P.R. XVI-Merlin 76/77 -6519A-12 (Hamilton Standard)
FB.V1-Merlin 23/25-6519A-12 (later aircraft)
Mk's VIII, IX, X, XIV –Merlin61-P/DP454912 (4 blade /12ft 0ins diameter)-1943
NF.XIII – Merlin 21 -DP454612
NF.XV- Merlin 77-P454912 (4 blade 12ft 0ins diameter)
NF.XIX – Merlin 25- P454612
BV.II-Merlin31 -6519A-12 (Hamilton Standard)
B.XVI-Merlin 113/114- DP454912 (4 blade 12ft 0ins diameter)
NF.30 – Merlin 113- P454912 (4 blade 12 ft 0ins diameter))
Mosquito 33- Merlin 25- DP45442706 (12ft 6ins diameter-4 blade)
Sea Mosquito- Merlin 113/114 – P454906/P4543706 (12ft 6ins diameter-4 blade)
Sea Mosquito –Merlin 25- P4542706 (12ft 6ins diameter-4 blade)
This does not cover all Mk's but should prove useful to readers. The '454612' type dH blades had wider tips and thinner sections than the original '455.'
I shall not list the variants but the Lancaster blade diameter is 13ft 0ins (P455800/DH6353A).
The prop diameters for Manchester and Stirling were 16ft 0ins(Vulture LHR) and 13ft 6ins respectively. The Halifax props eventually ranged up to 13ft dia.
As you will know, for all but very few Merlin engines the rotation is 'right hand' i.e. clockwise when viewed from the cockpit.
On the matter of the subject blade:
My impression is that it is designed for a hydromatic prop. The photos suggest a left-hand rotation which if correct, would effectively rule out a Merlin engined application so not applicable to Lancaster or Mosquito. As of 1941 we would be talking about the Hercules or development types e.g. Centaurus or Sabre.
Unless there is data stamp that has not been displayed, the principal identifier seems to me to be 'D40550A' which I take to be the blade drawing number. I should have thought that a stamping error was unlikely so I have taken it at face value. I have not found such a number (D 40550 A ) in any of my listings/documents. This is not a standard production number. Initial characters on codes for bracket prop blades would be P/DP 55xxxx (56xxxx for the greatest diameters) and for hydromatics P/DP 455xxxx /P/DP 454xxx(for the hydromatic, the third number identifies the blade shank size, second number in the case of the bracket types).
Experimental blades were prefixed ' SKP'(the number being different to that of the subsequent production version). All in all therefore, this example seems to be in an unusual class.
Taking the diameter of the shank of the subject blade should at least confirm the shank size i.e. 4000 or 5000.
The closest match I have is P454550, a left hand rotation hydromatic blade of 11ft 5ins diameter with no aircraft designation but which was suitable for a standard feathering of non-feathering 3 way(i.e. blade) or contra-rotating hub. However, given the measured blade length this seems to be no more than co-incidental.
Speculating by reference to the DH numbering system, the final 3 numbers may indicate a 'master' blade which could be used in its own right or cut-down to produce lesser diameter variants.
As another speculation, the blade might be a DH copy of an HS blade using a 'D' prefix although I am not aware of any corresponding drawing numbers.
In conclusion, something of a conundrum but quite possibly an experimental/developmental blade. I hope this helps.
End message.
Firstly Mosquito and Lancaster blades. These are all hydromatics :
'I had a look through sections of my files. This is not a complete listing of propeller types but a shortened version (i.e. to save my time, full designation not always provided) of blade types used with various Mk's of Mosquito:
Mk's I/II/III/V - Merlin 21- P4551212 (original Mosquito 'narrow' blade 12ft 0ins dia.)
B.XVI –Merlin 72/73/76/77 –DP454612
B.XVI - Merlin 76/77/113/114 -6519A-12
P.R.I/FII/BIV/NFXII- Merlin 21 or 23 – DP4551212
P.R .I/IV/VIII- Merlin 21/23/72 –P4551212
P.R. VII– Merlin 72- DP4551212
P.R. XVI –Merlin 72/73/-P4551212
P.R. XVI-Merlin 76/77 -6519A-12 (Hamilton Standard)
FB.V1-Merlin 23/25-6519A-12 (later aircraft)
Mk's VIII, IX, X, XIV –Merlin61-P/DP454912 (4 blade /12ft 0ins diameter)-1943
NF.XIII – Merlin 21 -DP454612
NF.XV- Merlin 77-P454912 (4 blade 12ft 0ins diameter)
NF.XIX – Merlin 25- P454612
BV.II-Merlin31 -6519A-12 (Hamilton Standard)
B.XVI-Merlin 113/114- DP454912 (4 blade 12ft 0ins diameter)
NF.30 – Merlin 113- P454912 (4 blade 12 ft 0ins diameter))
Mosquito 33- Merlin 25- DP45442706 (12ft 6ins diameter-4 blade)
Sea Mosquito- Merlin 113/114 – P454906/P4543706 (12ft 6ins diameter-4 blade)
Sea Mosquito –Merlin 25- P4542706 (12ft 6ins diameter-4 blade)
This does not cover all Mk's but should prove useful to readers. The '454612' type dH blades had wider tips and thinner sections than the original '455.'
I shall not list the variants but the Lancaster blade diameter is 13ft 0ins (P455800/DH6353A).
The prop diameters for Manchester and Stirling were 16ft 0ins(Vulture LHR) and 13ft 6ins respectively. The Halifax props eventually ranged up to 13ft dia.
As you will know, for all but very few Merlin engines the rotation is 'right hand' i.e. clockwise when viewed from the cockpit.
On the matter of the subject blade:
My impression is that it is designed for a hydromatic prop. The photos suggest a left-hand rotation which if correct, would effectively rule out a Merlin engined application so not applicable to Lancaster or Mosquito. As of 1941 we would be talking about the Hercules or development types e.g. Centaurus or Sabre.
Unless there is data stamp that has not been displayed, the principal identifier seems to me to be 'D40550A' which I take to be the blade drawing number. I should have thought that a stamping error was unlikely so I have taken it at face value. I have not found such a number (D 40550 A ) in any of my listings/documents. This is not a standard production number. Initial characters on codes for bracket prop blades would be P/DP 55xxxx (56xxxx for the greatest diameters) and for hydromatics P/DP 455xxxx /P/DP 454xxx(for the hydromatic, the third number identifies the blade shank size, second number in the case of the bracket types).
Experimental blades were prefixed ' SKP'(the number being different to that of the subsequent production version). All in all therefore, this example seems to be in an unusual class.
Taking the diameter of the shank of the subject blade should at least confirm the shank size i.e. 4000 or 5000.
The closest match I have is P454550, a left hand rotation hydromatic blade of 11ft 5ins diameter with no aircraft designation but which was suitable for a standard feathering of non-feathering 3 way(i.e. blade) or contra-rotating hub. However, given the measured blade length this seems to be no more than co-incidental.
Speculating by reference to the DH numbering system, the final 3 numbers may indicate a 'master' blade which could be used in its own right or cut-down to produce lesser diameter variants.
As another speculation, the blade might be a DH copy of an HS blade using a 'D' prefix although I am not aware of any corresponding drawing numbers.
In conclusion, something of a conundrum but quite possibly an experimental/developmental blade. I hope this helps.
End message.
ThomasP
Chief Master Sergeant
Something else that has not (I think) been mentioned is that just because it was manufactured in 1941 does not mean it was used in 1941.
ThomasP
Chief Master Sergeant
FWIW the blade profile appears (to me) to match the DH type used on the Halifax Mk III. But the normal blades used would have had a P prefix.
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