Mosquito carrier landings

[Synthetic]

Part of the recently shown "Plane that saved Britain" showed Eric Brown carrying out carrier landing trials. Even with the film frame strobe effect it was apparent that the Mossie used had four bladed propellors.

I had not come accros these on a Mossie before.

Can anyone shed any light on this? Was it just different props or was it different engines?

[Allan Lupton]

The photo in our book of the 50th anniversary Symposium has a photo of that landing in LR359 and they are four-blade props. The transcript of Winkle Brown's talk tells us that from the beginning the deck-landing Mosquitos were fitted with four-bladed non-feathering de Havilland propellors but although he explains the difficulty that caused, he didn't say why they had them.
Other photos in that chapter also have four-bladers and the aeroplanes are TS449 one of a pair of prototype TR/TF Mk.33s which also had RATOG fitted, LR387 the second ptototype TR Mk33 and VT724 a TR Mk37

[Meikleour]

Allan Lupton: In his book (Wings on my sleeve) he mentions that the engines were much uprated Merlins compared to the standard one fitted to the RAF Mossies and that the shorter prop blades were to avoid damage should the aircraft "nose over" on landing on the flight deck.

[Allan Lupton]

Thanks Meikleour. I thought shorter blades would be the reason for the four-blader, but couldn't quickly find a reliable source. Did he say why they were non-feathering?

[astir 8]

Brown also mentions a normal stalling speed (with u/c and flaps down) of 110 mph (sic) versus a maximum (calculated) permitted touchdown speed of 83 mph limited by the carrier arrester gear. Even deducting boat speed and wind speed this was a problem.

Quote from "Wings on my Sleeve"

"It was obvious that the only way I could get the landing speed down to that required was by approaching with a considerable amount of power on the engines and literally hanging on the propellers .....with this in mind my aircraft were fitted with Merlin 25's capable of operating at 18lbs boost instead of the standard 12 lbs and to absorb this extra power they were fitted with four bladed .... propellers cropped to 12'6 to avoid them touching the deck when they pitched forward on being arrested"....

"it was certain that any power loss on one engine would result in a fatal accident"

No wonder Mossies on carriers never went operational. And the sheer bravery of that man!

[cyflyer]

This is a passage from "De Havilland Aircraft since 1909" AJ Jackson/Putnum. It disagrees with the cropped prop aspect mentioned above, actually it mentions larger diameter...

scanned it here for you to judge, hope it helps.

http://i496.photobucket.com/albums/rr327/eurocypria/mossie.jpg

[Allan Lupton]

Quote:
actually it mentions larger diameter...

Sorry if I seem to be a nit-picker, but it says "large diameter" not "larger".
If nothing else, perhaps we could assume that the four-blader could absorb the extra power without extra diameter, whereas a three-blader to do that would have been to big for safety.

[cyflyer]

Allan, if it says 'large' diameter, does that does not mean 'large' as opposed to the 'normal' diameter, hence 'larger' than normal ?

[astir 8]

It had escaped me that there were actually production Sea Mosquitoes. The quote about the smaller diameter props may only have referred to Brown's original trials.

[Allan Lupton]

Well, cyflyer, who can say!
A four-blader to absorb the standard power would have been smaller than the three-blader so large could just mean larger than that.
What the photos do seem to show is that the propellors of the Sea Mosquito are similar in diameter to the three-bladers of the other Marks.
What we also know is that prop-strike was always a risk with arrester-gear landings, so keeping the diameter down, or reducing it, would have been sound engineering. Someone, somewhere, has the de Havilland Propellor Co's archive and could give us the real dimensions - I don't know who or where, but the Salisbury Hall people may know.
astir 8 - that's a good point. Could well have been the case.
Very few Sea Mosquitos were built before the war ended and the (Sea) Hornet, which was a better naval aeroplane, was used instead.

[DHfan]

It also says "first British twin-engined type" whereas to the best of my knowledge it was the first twin anywhere to land and take off from a carrier.
The Tokyo raid Mitchells were craned on board.

[Synthetic]

Thanks for the replies. :)

I really must buy a copy of Eric Brown's book.

[Brian Abraham]

De Havilland Mosquito: An Illustrated History - Ian Thirsk - Google Books (http://books.google.com.au/books?id=6nbDN5fUkyMC&pg=PA293&lpg=PA293&dq=sea+mosquito&source=bl&ots=1bMc-_8ie0&sig=Yi7cuKe_qdkI0BIPkPW-fOqmoKQ&hl=en&sa=X&ei=exn7Uc7rO8HQkgXo9ICoBQ&ved=0CHQQ6AEwCw#v=onepage&q=sea%20mosquito&f=false)

The link states the second of two special pre production aircraft, Sea Mosquito TR Mark 33, TS449, was fitted with props of 12 feet 6 inches diameter (Type D/14/445/2). Reason seems to be the 4 blade gave 5 to 10% greater thrust than the 3 blade, an advantage for the limited take off run on the carrier deck.

Edited to add; have been reading through a number of flight test reports on various Mosquito versions and it seems 12 feet was the standard 3 blade diameter. The high altitude 3 blade paddle prop seems to be 12 feet 6 inches. Others mentioned were 12 feet 1 inch 3 blade and 12 feet 4 blade (latter fitted to F Mk XV high-altitude, pressurised fighter). Whether they all were standard fit or experimental was not made clear, though report preamble seemed to suggest standard.