Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
And I guess that's another question. Is the cleanliness of the Hornet's Merlin installation worth 100% perusing on a single-seater (assuming Merlin 60 or 100 series power), or is that a bit far fetched from a practicality standpoint?
The height of the Merlin installation on the Hornet seems to be similar to the Merlin powered Spitfire and Mustang. I was asking about width. The Hornet nacelle seems to be really narrow, even for a single seat fighter.
Oddly, the Hornet's fusalge was claimed to be only about 10% or so wider/taller than a normal single seat fighter's (you have to put the 4x20mm cannons somewhere, and the nose is most practical on a single seat twin).
Depends on the fighter.
If the fuselage is of small height (like on the Bf 109, MC.202/205, Allison-engined P-51), the smaller height of the engine is a bonus. If the fuselage is taller (like on the Spitfire, Merlin Mustangs, Fw 190), the practical gain in streamlining from the less tall engine is probably very low.
Yes.You think the Spitfire has a deeper fuselage than the Mustang?
And the the Allison P-51 fuselages are much smaller than the Merlin P-51 Mustangs?
Also, the Hornet's cowling is much smoother than the Griffon-powered Spitfires, which has fairings to clear the valve covers (maybe a wider spinner would've helped the Spitfire and Spiteful?).
One wonders whether the people at Napier accounted for the drag of the wing section behind where the LE radiators go, when doing their math. With the annular radiator, there is the drag of that radiator + the full drag of that section, while with the LE radiators a good deal of the drag of that wing section is already accounted for with the radiator drag.According to Napier tests an annular/drum radiator installation with sliding gill cowling would be the least draggy. So the leading edge radiator of the Hornet was not the best in terms of drag even in conjunction with the narrow nacelles.
And I guess that's another question. Is the cleanliness of the Hornet's Merlin installation worth 100% perusing on a single-seater (assuming Merlin 60 or 100 series power), or is that a bit far fetched from a practicality standpoint?
One wonders whether the people at Napier accounted for the drag of the wing section behind where the LE radiators go, when doing their math. With the annular radiator, there is the drag of that radiator + the full drag of that section, while with the LE radiators a good deal of the drag of that wing section is already accounted for with the radiator drag.
Meaning at the end that LE radiators have no disadvantage wrt. drag of a whole aircraft.
Another concern is that engines employing intercooler can increase the drag even if the installation is unitary and in annular form. Eg. the Ta 152, with an intercooled engine that dictated a bigger annular radiator (there was no separate radiator for intercooler, coolant and oil system*), have had 0.061 sqm worth of cooling drag, vs. 0.039 sqm on the non-intercooled engines as were the 213A and 213F - a 50+% increase of the cooling drag.
So just because the annular radiator was good for the Napier Sabre, it does not mean that it woukd've been a great solution for the 2-stage Griffon. Then we also have a thing of the aircraft with LE radiators, like the prototype Tempest I and Fury, as well as Hornet, being really fast already.
* coolant and oil were cooled via the heat exchanger, same as with other Jumo 213s, plus the intercooler was also cooled via the heat exchanger on the 213E
Do I undestand it right that your argument concerning the LE radiator also applies to the annular one (snowygrouch?I dont think "Blanket" statements are very easy to make.
As has already been stated above, where you already have a very big fuselage, the annular system will work well because
you`re just making use of air which would have been shoved out the way of the aircraft anyway.
Something like a hornet clearly needs to have the diameter of the nacelles increased considerably to fit the
annular radiators, therefore increasing the frontal area, probably negating the benefits.
There are probably about two or three definitive layouts which will all work very well in the correct circumstances.
Just look at Reno Unlimited`s, thats been won by annular air cooled (effectively no different to a water cooled annular) and belly scoop systems (p51),
and planes like Sea Fury`s which have both leading edge and annular cooling systems at once.
I think the only thing you can conclude, is that stuffing a radiator out the bottom of the wing in a lump like a Spitfire is probably just about
bottom of the pack (although it can be very nicely done - see Supermarine Spiteful).
The FLIGHT articles (there are two) were comparing not just the annular radiator, but the later article in combination with a ducted spinner, and against the chin radiator version,
which is a pretty horrid looking lump at the best of times.
Certainly I have a lot of enthusiasm for the ducted spinners, although FW found them a bit difficult to get working on the 190 and ended up
with the more basic annular system we all know.
The annular installation here makes it pretty clear its making use of "dead space" in terms of fuselage diameter compare to the
approximate size of the actual engine (my blue lines added in). Very noteworthy here is the arrangement of the fins in the radiator matrix,
angled to align with the airflow. A lot of the benefits here will be down to excellent radiator matrix design too, not just where its fitted (as such).
Not dissimlar to that suggested by Kuchemann and Weber at Volkenröde. (yes, THE Joannah Weber, of Concorde fame when she ran off to
carry on doing maths for the British after the war)
View attachment 673909
View attachment 673908