DH Hornet nacelle frontal area?

[BarnOwlLover]

I do wonder how a Hornet's nacelle frontal area compares to that of a Mosquito's (I read somewhere in the neighborhood of 10% smaller, but I can't remember where), as well as the Mustang fuselage and the fuselage of a Griffon Spitfire. IMO, the Hornet nacelle and Griffon Spitfire fuselage forward of the cockpit look eerily similar in line and several contours without the valve cover fairings on the Spitfire, as well as the Hornet nacelle having several line and contour similarities with the Merlin Mustangs if you delete the supercharger intake off the Mustang.

Maybe I should phrase it as "is it worth it to get DH Hornet levels of power unit streamlining on a single seater" as far as reducing frontal area. Which, after all, was the point of the Merlin 130 engines for the Hornet having stuff moved around (reduce nacelle frontal area). Though, oddly, at the time the Hornet was conceived, the Merlin 60 series engines were what was initially envisioned for it.

 

[tomo pauk]

Maybe I should phrase it as "is it worth it to get DH Hornet levels of power unit streamlining on a single seater" as far as reducing frontal area. Which, after all, was the point of the Merlin 130 engines for the Hornet having stuff moved around (reduce nacelle frontal area). Though, oddly, at the time the Hornet was conceived, the Merlin 60 series engines were what was initially envisioned for it.

Is the post #2 here of any use?

 

[BarnOwlLover]

This is one of several reasons why I'd love to see the DH Hornet that's being rebuilt in New Zealand at least be rebuilt to static status, let alone airworthiness. If so, it'll hopefully attend airshows so it can be compared in terms of size and such to Spitfires and Mustangs.

As far as tight cowlings go, look at this illustration of the Supermarine 327 proposed fighter. It was a single stage Merlin, but look at how compact this looks as far as the design doc. Also note the engine bearer/subframe, and its similarities to the Griffon-powered Spitfires and such:

 

[BarnOwlLover]

Also another reference, here's a P-51D Mustang in service with the RCAF, and a DH Hornet under engine maintenance with a RAF ground crew. I know that human heads are different sizes, but using what little I've been able to discern, using the human head as a reference, the Merlin Mustangs and the Hornet use similarly sized spinners and the engine cowlings are similarly tall.

 

[spicmart]

Were the Germans able to build extra slim versions of their engines? And if so, which one?

 

[tomo pauk]

Were the Germans able to build extra slim versions of their engines? And if so, which one?

DB 601-605 were rather slim already, IMO, especially concerning the swept volume.

 

[BarnOwlLover]

Been looking at the British Air Ministry pics on here, and it seems that for what I'm looking at (Hornet's engine nacelle frontal area and size vs a single seat fighter fuselage) that the Hornet's nacelle is too small to be mated as far as the power unit to a single seat fighter's fuselage.

On the other hand, the DH Mosquito's nacelle seems similar in size to a single seat fighter's fuselage as far as using a Merlin engine. The spinner and front section between that and the exhaust section's leading edge is fairly wide, but could be slimmed down to Hornet or Mustang proportions. Also helps to remember that the single stage and two stage powered Mosquitos used standard Merlins, while the Hornet used the Merlin 130 with moved around ancillaries. The Mosquito's nacelle is taller, mostly because of how it was fared into the wing.

 

[Shortround6]

The cockpit, even on a Spitfire, has more frontal area than the Merlin engine of either standard type or the 130 series.

Since you can't make the cockpit area/cross section much smaller all you are going to get from using the 130 Merlin form is a bit better blend of the lines from the spinner to the cockpit.

It would also be interesting to see what people want to do with the carb inlet.
The Hornet stuck the carb inlet outboard in the wing as in BarnOwlLover's Post #24

 

[tomo pauk]

The cockpit, even on a Spitfire, has more frontal area than the Merlin engine of either standard type or the 130 series.

Since you can't make the cockpit area/cross section much smaller all you are going to get from using the 130 Merlin form is a bit better blend of the lines from the spinner to the cockpit.

Take advantage of the now freed frontal area to install intercooler and/or oil cooler under the engine, so the drag is lowered?

It would also be interesting to see what people want to do with the carb inlet.
The Hornet stuck the carb inlet outboard in the wing as in BarnOwlLover's Post #24

Carb air have had an ... interesting path on the Hornet. It 1st entered the intake in the LE, then ot tured 90 deg towards fuselage, then turned 90 deg into the carb.
(similar set-up was on the F7F)
My take on Merlin 130 intake on the Spitfire and the like is that they will be very similar to the Allison-egined P-40s or P-51s.

 

[Engineman]

Were the Germans able to build extra slim versions of their engines? And if so, which one?

The DB 605 A/B was quite well packaged, having inherited most of it's layout and external dimensions from the DB 601, particularly the DB 601 E. The DB 605 AS introduced a marked increase in the engine width at the supercharger, which extended to the LHS and had an increased diameter. This required the extension of the LH cowling bulge and a larger intake scoop. Increased oil cooler size was also incorporated on most aircraft to match a higher heat rejection to the engine oil.
The 1944 DB 605 D engines also had the larger supercharger and introduced forward cam cover mounted scavenge pumps that required bulges on the lower hinged cowling. Some later Bf 109's had changed cowling contours to accommodate these pumps.
Introduction of the Olschluder oil deaerator on the D engine required extra space on the rear RHS of the cowling as well as modifications to the forward bulkhead area and so the right cowling and fairing was also modified to provide greater width as well.

Eng

 

[Shortround6]

Take advantage of the now freed frontal area to install intercooler and/or oil cooler under the engine, so the drag is lowered?

Is it or have you just changed where the drag occurs?
yes the oil cooler in the under wing "box" with the radiator doesn't look good but you need a certain amount of air flowing through the oil cooler and you have to duct the air in and out.

 

[tomo pauk]

Is it or have you just changed where the drag occurs?
yes the oil cooler in the under wing "box" with the radiator doesn't look good but you need a certain amount of air flowing through the oil cooler and you have to duct the air in and out.

The radiator(s) under a less tall enigine don't add to the frontal area, unlike the radoators used on 2-stage supercharged engines Spitfire/Spiteful used. Ideally, the lower nose would've been shaped as on the XP-40Q-2.

 

[BarnOwlLover]

My question is height of the Hornet's nacelle vs most single seat fighter fuselages. I do think that the rear of the Hornet's nacelle is too short to be "graphed" onto like say a Mustang or maybe even a Spitfire's fuselage. To guage how small in height the Hornet's nacelle is, look at post 24 and look at the size of the rear of the nacelle vs the people working on the engine.

Even if you put a normal Merlin with an updraft supercharger intake on the Hornet, there may still be a size difference. For comparison, here's pics of a Hornet, two stage Mosquito, Mustang III/P-51B and a two stage Merlin Spitfire.

 

[Shortround6]

I think to get any sort of benefit you need an entirely new plane. The Spitfire's cockpit sat on top of the wing. So the bulkhead/frame where the instrument panel went was 31in high by 34in wide which is about 4 inches wider than most Merlins. The height is a bit short but you have pretty much the whole main spar under the fuel tank/cockpit.
I would also note that the Spitfire is rather flat on top. Not a lot of change of height from the cockpit, over the fuel tank and over most of the engine. The P-51 has a taper the whole way.

 

[pbehn]

You can make a Spitfire's contours more like that of a Hornet but you need to move the oil tank somewhere else.

 

[BarnOwlLover]

Also looking at the Mustang, even the Allison powered versions had the deep engine cowling (lower cowling) that the Merlin powered versions would, even though the Allison V-1710 had a downdraft supercharger feed.

As far as cowling upper panel taper, here's a cutaway (how accurate I don't know, but hopefully demonstrates it) of a P-51D, XP-51G, and P-51H

 

[tomo pauk]

Also looking at the Mustang, even the Allison powered versions had the deep engine cowling (lower cowling) that the Merlin powered versions would, even though the Allison V-1710 had a downdraft supercharger feed.

I'd say you have it the other way around - Merlin Mustangs were with the deeper cowling. Despite the Allison Mustangs provision for the cowl/fuselage .50s.

FWIW

 

[SaparotRob]

Either way they sure are pretty.

 

[pbehn]

Either way they sure are pretty.

Its the roundels that do that, well worth the 20MPH you lose in top speed.

 

[BarnOwlLover]

Here's a pic for some perspective. Here's the power units (minus props) for a DH Mosquito prior to being attached to the wing. This should give some idea of scale as far as what I'm trying to talk about.

The spinner on the Mosquito was actually somewhat huge compared to like say a Mustang's or Hornets, though in fairness, the coolant header tanks on the Mosquito were fairly large compared to a Mustang or Hornet as well. I'd bet that making that component smaller was a part of slimming down the Hornet's nacelle.