Mosquito Mk VI Props

[Mark P]

Hi:

 

I am looking for details specific to the useage of paddle blade props on the Mk VI Mosquito. Can anyone tell me when there use began and if possible what serial number block? Could these paddle blade props be retro-fitted to earlier airframes delivered with the narrow blades?

 

Any insight, or suggested references discussing this feature would be greatly appreciated.

 

Mark Proulx

[Dave T Brown]

The 12' 6" dia de Havilland Hydromatic "Paddle Blade" Propellers were developed to help increase the high altitude performance of the twin stage engined variants, as the larger blade is more efficient at highter altitudes which the twin stage variants were optimised for eg the BIX, BXVI, PR.XVI and NF.XXX to name but a few.

My research leads me to the following conclusion. Paddle blade props were introduced in mid 1944 and were initially fitted to twin stage variants. When production of propellers was in full flow they were fitted to other variants on the production line. Single stage night fighters being next followed by the FB VI whose engines were, generally speaking actually optimiosed for low level performance.

For de Havilland built machines the Paddle blades started to be fitted during production to the PZ serial range and Standard Motors built machines in the middle of the HR serial range. However for example they must have been retro fittable as HR143 an early Standard Motors built machine was fitted with them.

I would suggest that photographic evidence be consulted if you plan to fit the Paddle blade to earlier production batches to those mentioned earlier.

Hope this helps.

[Mark P]

Dave:

 

Thank you very much for your prompt reply. I am trying to determine how wide spread, if at all, the practise was with 418, an RCAF Intruder unit.

 

Mark Proulx

[t.valdez]

Some photos of Mosquitoes show Hamilton Standard logos on the prop blades which seems to suggest that deHaviland of Canada was sourcing them from US suppliers and/or they were license built by deHaviland. Although OOP, Paragon Designs did make a resin prop set, individually molded blades and a prop hub. No template though so you needed to use the Mk 1 eyeball mounting method to get the right look. While not totally accurate, you can cheat and use the old Revell Corsair props in lieu of the OOP tiems mentioned. Recon Mossies seem to be the ones I recall as having Ham. Standards.

[Allok]

Combat/Roberts has the Horizon Conversions set with paddle blades. I was going to buy a set for my RNZAF project.

[PhilB]

Combat/Roberts has the Horizon Conversions set with paddle blades. I was going to buy a set for my RNZAF project.

Keith,

Being a source of infinite knowledge, you wouldn't happen to have any idea where I could lay my hands on a set of

paddle props for my 1/32 Revell mossie I'm resurrecting now I've got the Paragon conversion?

 

Phil

[Anthony in NZ]

Hi Phil

 

You might try contacting Neil at Paragon, he may have some left. I had all the Mossie stuff he did in 32nd at one stage. Neil knows Mossies well and you simply wont find more accurate parts.

 

I havent seen the others, but they would have to be pretty special to beat Neils offerings.

 

Just my .02 cents worth

 

Cheers

Anthony

[PhilB]

Hi Phil

 

You might try contacting Neil at Paragon, he may have some left. I had all the Mossie stuff he did in 32nd at one stage. Neil knows Mossies well and you simply wont find more accurate parts.

 

I havent seen the others, but they would have to be pretty special to beat Neils offerings.

 

Just my .02 cents worth

 

Cheers

Anthony

Thanks Anthony,

I had a feeling that he may have done them at one time, hope he still has the moulds!

I'll Pm him.

 

Phil

[paragondesigns]

Thanks Anthony,

I had a feeling that he may have done them at one time, hope he still has the moulds!

I'll Pm him.

 

Phil

 

Phil

 

Yes, I still have all the moulds. Actually, your canopy etc was dropped in the post yesterday afternoon, I could of put some paddle blades in there too if I had known earlier

 

(I may of included a product list with your order last week, all of the Mosquito stuff I made should be listed on there if I did, they should be in the 1/32 section as 'TBA').

 

 

Neil.

[Dave T Brown]

The 12' 6" dia de Havilland Hydromatic "Paddle Blade" Propellers were developed to help increase the high altitude performance of the twin stage engined variants, as the larger blade is more efficient at highter altitudes which the twin stage variants were optimised for eg the BIX, BXVI, PR.XVI and NF.XXX to name but a few.

My research leads me to the following conclusion. Paddle blade props were introduced in mid 1944 and were initially fitted to twin stage variants. When production of propellers was in full flow they were fitted to other variants on the production line. Single stage night fighters being next followed by the FB VI whose engines were, generally speaking actually optimiosed for low level performance.

For de Havilland built machines the Paddle blades started to be fitted during production to the PZ serial range and Standard Motors built machines in the middle of the HR serial range. However for example they must have been retro fittable as HR143 an early Standard Motors built machine was fitted with them.

I would suggest that photographic evidence be consulted if you plan to fit the Paddle blade to earlier production batches to those mentioned earlier.

Hope this helps.

I feel I must elaborate slightly on the reason for the development of Paddle Blades for the Mosquito as performance at altitude was not the main reason for developing paddle blades but it is however an advantage at altitude.

With the development of the twin stage variants of the Mosquito the need to harness the additional power produced by the twin stage engines was paramount and an increase in propeller “Solidity” became a fundamental requirement.

This can be achieved by increasing the blade area as was done on paddle blades or increase the number of blades from 3 to 4 as was done on the Spitfire when it went from a single stage Merlin to a twin stage Merlin.

By increasing the Solidity of the propeller it effects the blade loading which can become the limiting factor when transmitting power from the engine, through the propeller, in to forward thrust.

Hopefully it can be seen from the above that increased blade area is beneficial to “thrust” I therefore surmise that once production of the 12’6” diameter Paddle Blade propellers was in full swing de Havilland took the decision to fit this standard of propeller to all variants of Mosquito then under production and stopped the production of the 12’ diameter needle blade props.

[Whitta]

Hello Dave,

The reasons you gave for the Paddle installation are very useful. The only question that arises is why DH would then equip the Sea Mossie and the J.30 with 4 needle blade props, if they had ceased production of the 3 blade variety?

[Dave T Brown]

Hello Dave,

The reasons you gave for the Paddle installation are very useful. The only question that arises is why DH would then equip the Sea Mossie and the J.30 with 4 needle blade props, if they had ceased production of the 3 blade variety?

I do not have info on the four blade propeller sections and it is probable that they are not the same blades used in the earlier three blade "needle" propellers. However if they were it would not be difficult to restart production as I doubt the tools for making them would be scrapped. Further more a 4 blade propeller requires more redesign as the hub, feathering equipment and constant speed unit would all require redesigning. For some reason de Havilland decided to use the increased diameter 3 paddle blade unit as the standard for the later marksof Mosquito.

It is likely that the 4 blade unit used as standard on the Hornet was that fitted to the TR.33 Sea Mosquito, the J.30 and Turkish Airforce FB VI's all of which use the single stage Merlin engine.

[Dave T Brown]

The 4 blade units used on the TR.33 were 12'6" diameter and therefore are highly unlikely to use the same blades as the earlier 12' diameter 3 needle blade unit, found on early Mosquitos.

It was found that the 4 blade unit gave a 5 to 10% thrust improvement over the standard 3 blade unit and this was vital for a shipboard role where maximum thrust and revs are required from the onset of the short take off run.

The "Highball" modified BIV's delivered to 618 squadron also had 12'6" dia 4 blade propellers fitted, presumably because of its perceved shipboard role.

[JackyEMERY]

Bjr, suis nouveau sur ce type de discution... Pardonnez si je ne "fonctionne" pas comme il faudrait.

J'ai été contacté pour identifié une pale d'hélice... Je suis un peu "sec"... Par rapport à mes recherches de crash d'avion alliés sur la Sarthe, j'ai une petite idée...

Je la partagerais avce ceux qui me répondront. Par avance merci.