Napier Sabre Annular Radiator ...

[Mark Allen M]

One major problem with the design of the Hawker Tempest and Typhoon aircraft was that they had a large ‘chin’ radiator. If another aircraft got into trouble it could belly flop land, in a field for example, and slide along the ground to a standstill. The chin radiator fitted to Napier Sabre powered aircraft meant that any such landing was much more risky because it would make contact with the ground first, dig in and flip the aircraft over.

Napiers spent a great deal of time researching and developing a range of solutions. The requirement was to allow sufficient airflow across the radiator with adjustment to correctly regulate the cooling. This increased as the engine Series was developed and required extra cooling.

The solution was to create an annular radiator allowing air to pass through the spinner of the aircraft. As can be seen in the images several types of annular radiator were tested and developed. In reality very few Sabre engined aircraft actually received this modification die to the war ending. The unique Vickers Warwick HG248 was the only twin engined Sabre aircraft and it had annular radiators.
Source: https://npht.org/napier-sabre-annular-radiator/

As part of the power plant testing, Napier had developed a unique annular radiator for use on the Tempest, in an effort to streamline the aircraft by doing away the big scoop radiator.
The radiator development program used two modified Tempest Mk. V, serials EJ518 (fitted with a Sabre VI) and NV 768. NV 768 was later fitted with a ducted spinner with the same diameter as the fuselage and, although test flown, the spinner was not actually planned for use on production Tempests. Neither feaure was incorporated onto Tempest production line and the aircrafts were scrapped after the war.

Much more detail here:
https://www.key.aero/article/playing-it ... nd-tempest


Hawker Tempest V NV768 experimentally fitted with a ducted spinner and an annular radiator.

[Jim MacDonald]

And they called the Corsair the "Hose Nose". Must have been a real challenge to see over that nose during landing.

Mac

[LysanderUK]

I've seen mention of this experiment before, but never seen such extensive pics. Thanks for these.

Regards the belly-landing characteristics with the conventional radiator, there are numerous accounts of Typhoons and Tempests making good belly landings, so I think the danger in belly landings has been somewhat overstated over time.

On the other hand, ditching was to be avoided at all costs. I have a facsimile copy of the Mk.Ib Typhoon Pilot's Notes that states to avoid ditching if at all possible (the Notes for the Hurricane are only slightly less heavily emphasised when it comes to ditching).

[Archer]

I have seen this image labelled in various incorrect ways... but it shows the same NV768 with the annular radiator but a somewhat more regular looking spinner setup.

DBFwCTDXsAAg92P.jpg (40.35 KiB) Viewed 2217 times

[Larry Kraus]

As to LysanderUK’s reference to ditching recommendations for the Typhoon, here is a page from the Pilot’s Notes for the Typhoon Mk IA and IB

IMG_8973 by tanker622001, on Flickr

This is for the Tempest Mk II. In both cases it looks like ditching is a last resort.

IMG_8975 by tanker622001, on Flickr

IMG_8976 by tanker622001, on Flickr

[Archer]

Just a thought, but I suspect that other single-seat fighters from that era will have similar suggestions in the pilot's notes. I wonder which prop-driven WWII fighter would be easy to ditch... if any.

[Dave Hadfield]

I suspect a Zero might ditch OK. But when I've flown fighters across Lake Michigan while visiting OSH (55 nm), I wear a mae-west as well as the parachute, and would plan to bail out, not ditch, if the engine quit or caught fire.

FWIW, the cowls on something like a P-40 are just that, sheet-metal, and are not all that rigidly attached to the airframe. Just dzus fasteners. Some cowls don't attach to the airframe at all, just each other (Fairchild 24W). They would tend to rip off with a water impact, I think -- although I'd rather not find out.

And the radiators are held with steel bands like king-sized hose clamps. That's all. Again, they'd tend to rip off.

[Larry Kraus]

I had the same thought as Archer about other fighter aircraft of the era probably having similar warnings about ditching. My Spitfire manual didn’t have anything to say about ditching. However, here is a sample of instructions for some fighters. Not surprisingly, the F6F and F4U have excellent ditching characteristics, the P-51 and others not so much.

From a P-51D Flight Manual

IMG_9016 by tanker622001, on Flickr

This is from the P-51 Pilot Training Manual

IMG_9047 by tanker622001, on Flickr

From the P-47 Pilot Training Manual

IMG_9018 by tanker622001, on Flickr

From the P-40 Pilot Training Manual

IMG_9022 by tanker622001, on Flickr

P-38H Flight Manual

IMG_9027 by tanker622001, on Flickr

From the P-38 Pilot Training Manual

IMG_9048 by tanker622001, on Flickr

P-39 Flight Manual

IMG_9025 by tanker622001, on Flickr

IMG_9026 by tanker622001, on Flickr

FM-2 Flight Manual

IMG_9075 by tanker622001, on Flickr

F6F-3/5 Flight Manual

IMG_9020 by tanker622001, on Flickr

F4U-4 Flight Manual

IMG_9100 by tanker622001, on Flickr

IMG_9101 by tanker622001, on Flickr


Pilot’s Notes for Hurricane MkIi

IMG_9029 by tanker622001, on Flickr

Beaufighter Pilot’s Notes

IMG_9030 by tanker622001, on Flickr

Mosquito Pilot’s Notes

IMG_9031 by tanker622001, on Flickr

That’s all that I gad tine to look up at the moment, but they should give a good idea of contemporary aircraft ditching instructions

Last edited by Larry Kraus on Wed Jun 28, 2023 8:53 pm, edited 3 times in total.

[Archer]

Thanks for that Larry! I was thinking that everything with a large scoop at the bottom (P-40, Typhoon/Tempest, P-51, Hurricane, etc.) would most likely have the same tendency in such a situation. The pilot's notes appear to support this. Even though the cowling and radiators are just held on by Dzus fasteners and some clamps (exaggerating a bit here), the energy needed to strip this back will still decelerate the airframe significantly, increasing the risk of it turning over and at the least providing a significant hazard towards the occupant.

[Noha307]

One has to wonder if they were influenced by the Fw 190. Given its surprising performance advantage vis-a-vis the Spitfire, the lack of external air scoops must have been an attractive option. Indeed, the 190 prototype had a ducted spinner:

(Source: AirPigz)

...and the cooling fins it ended up with could be considered a less extensive version of that.

[Duggy009]

One has to wonder if they were influenced by the Fw 190. Given its surprising performance advantage vis-a-vis the Spitfire, the lack of external air scoops must have been an attractive option. Indeed, the 190 prototype had a ducted spinner:

(Source: AirPigz)

...and the cooling fins it ended up with could be considered a less extensive version of that.

"As a result of the termination of the Tornado project, Sydney Camm and his design team transferred the alternative engine proposals for the Tornado to the more advanced Tempest.Thus, it was designed from the outset to use the Bristol Centaurus 18 cylinder radial engine as an alternative to the liquid cooled engines which were also proposed. A pair of Centaurus-powered Tempest II prototypes were completed. Apart from the new engine and cowling, the Tempest II prototypes were similar to early series Tempest Vs. The Centaurus engine was closely cowled and the exhaust stacks grouped behind and to either side of the engine: to the rear were air outlets with automatic sliding "gills". The carburettor air intakes were in the inner leading edges of both wings, an oil cooler and air intake were present in the inner starboard wing. The engine installation owed much to examinations of a captured Focke-Wulf Fw 190, and was clean and effective."

[bdk]

I was thinking that everything with a large scoop at the bottom (P-40, Typhoon/Tempest, P-51, Hurricane, etc.) would most likely have the same tendency in such a situation...Even though the cowling and radiators are just held on by Dzus fasteners and some clamps (exaggerating a bit here), the energy needed to strip this back will still decelerate the airframe significantly, increasing the risk of it turning over and at the least providing a significant hazard towards the occupant.

The P-51 scoop is somewhat rigidly attached, especially the rear portion behind the radiator which is actually part of the fuselage.