Which of these DB 601 powered fighters was the best? Bf 109F-2, Ki-61-I or C.202

[Shortround6]

The Hisso (and it's Russian derivatives) had the intake system on the outside of the engine.

Propeller reduction gear has to be sized for the proper off-set, supercharger has restrictions on size or location (German engines had theirs on the side for this reason).

The engine HAS to be designed with the motor cannon in mind to begin with, not added later. It has little to do with upright or inverted.

 

[cimmex]

Just to throw something in here, we are restoring an Hispano Ha.1112, which is esentially a Bf 109G from the firewall backward, with a Merlin in the nose. Since the Merlin was not an iverted V-12, there was no possibility for it to have a cannon through the spinner. Don't know about the REST of them, but OUR Hispano has wing armament and wing tanks. The wing armament was two Hispano HS-404 20 mm cannons ... IN the wing. I have seen the inside of the wing structure and the mounts are not only possible, they are there. It also had outboard wing tanks that we have removed since ours will be an airshow aircraft and doesn't need the extra fuel.

So, if the Germans had wanted to install wing cannons, they certainly could have, since the Spanish, with no other alternative, DID.

if you look at a Merlin you can see that the super-charger is at the back after the engine so there is no way to install a motor cannon. This has nothing to do with carb or injection, upright or down, there was just no space. The DBs had the super-charger side-mounted and there is some room between the cylinder banks for a cannon.
The Spanish built a complete new wing for the Ha.1112 to install cannons. It is a twospar design and was constructed to the fit the cannon.
Thousand of photos you can find at Matthias Dorst fantastic site:
Matthias -Strega- Dorst, die Adresse fr den Warbird-Enthusiasten und Modellbauer

 

[Tante Ju]

I also wonder if it has to do anything with carb injection... the DB 600 was carburrated, yet I believe layout was exactly the same as DFI 601 series.. so I dont think its carb/DFI/inverted layout related. Either you design an engine as such or not. The French did, and the Germans, who were looking closely at all French weapons systems probably followed the trend to counter.

 

[Ivan1GFP]

The Hisso (and it's Russian derivatives) had the intake system on the outside of the engine.

Propeller reduction gear has to be sized for the proper off-set, supercharger has restrictions on size or location (German engines had theirs on the side for this reason).

The engine HAS to be designed with the motor cannon in mind to begin with, not added later. It has little to do with upright or inverted.

Even the Jumo 213A could not mount a motor cannon. Accessories were in the way. The 213E/F could and did have motor cannons.

- Ivan.

 

[Civettone]

It's worth to note however than a C.202 had his maximum speed at 5900m. Higher than a Bf109 F1/2 with the DB601N (5200m) and similar to a F4 with the DB601E (6000/6200m)

I read yesterday that the RA.1000s received an upgraded supercharger, similar to that of the DB 601A-1.

And I also read that the RA.1000 used more plain bearings (as opposed to ball bearings) than the DB 601.
Kris

 

[Dogwalker]

And I also read that the RA.1000 used more plain bearings (as opposed to ball bearings) than the DB 601.
Kris

Yes, this is known. The Ra.1000 used mainly plain bearings, probably to save chromium and other steel alloy elements.

Good info on the supercharger.

 

[cherry blossom]

...
Rb 75/30 was quite a serious camera equipment, used for high altitude work with great focal lenght.
...

I looked at R.V. Jones' "Most Secret War" and he confirms the inferiority of British cameras on pages 179-181. However, the RAF managed to get equivalent or better results by developing the technique of taking two photographs to give a stereo view (which AFAIK the Germans never used). As well as the three-dimensional view often allowing camouflaged targets to be identified, there was also the advantage that rotating radar aerials could be identified.

 

[Civettone]

I have also read that the British were the first to use stereoscopic imagery. All started with Sidney Cotton.

But a quick google brought me to the another forum, from which I quote Chris Going:

It is the camera intervalometer setting which governs whether or not you will have stereo cover of a stretch of ground. The basic set-up of split verts, with a single area collector with a shorter focal length should all give you decent stereo cover. With the split verts the preferred setting is usually 10% sidelap (ie overlap between port and starboard), and 70% endlap ir overlap between frames of the same camera (the exact figure may vary). Having said that, Ive gone through Luftwaffe sorties which have 90% or more endlap. My conclusion is that Luftwaffe aircrews often didnt like the idea of bringing back unused film so had their intervalometers turning on maximum settings much of the time.

On another note stereo photography was being taken in the first world war and stereo pairs were being routinely distributed by the Brits c late 1916

So it seems it wasn't that rare after all.
Kris

 

[GregP]

Thanks Shortround. Nice pic of a 12YBrs!

I must admit I wasn't thinking of the Hisso at the time ... I made the mistake of thining of the Merlin, Griffon, and Allison. I also didn't think of the Mikulin or Klimov derivatives that started from the Hispano-Suiza 12YBrs ... though I don't think any Mikulin I can recall had a cannon through the hub. We already know the Atsuta was a Japanese licensed copy of a DB and did have the capability of firing a cannon through the hub.

So the HS has that as a positive. The big negative wasn't reliability, it was low power. I don't think I'd trade the extra power of an Allison, Merlin, or Griffon for a prop hub cannon, but some might well do so.

I haven't really dug into the Mikulin yet as the data are so few and far between. The only running Mikulin engine I know of is in a restored MiG-3 in Russia. It has engine problems almost every time they start it, if you believe the press. My guess, if they ARE having constant engine issues, is that they don't have the main bearing clearances quite right. Too tight gets hot quickly and too loose means poor oil pressure. Maybe we could send them some plastigage!

I think it does have a LOT to do with being upright. The most produced V-12 engine for the Allies was the Merlin. The intake system would have to be completely redesigned for a prop hub cannon. Same for the Allison or Griffon and, if it WAS, you'd have to have a very short cannon to clear the supercharger ... or move it to the side as on a DB.

I think it was said correctly above, you can design for a center cannon, but it is very difficult to "add" it later. The main Western upright V-12's weren't designed for center cannons, and that was my point, not that you CAN'T do it, but they mostly didn't opt for it. Not sure anyone would want to redesign a Merlin for a center cannon ... and the Allison simply wasn't ever going to be redesigned just for that option. If they had thought of it (or specified it) at the time things got started, the Griffon was a real possibility foir designing in a center cannon. But it wasn't done.

 

[cherry blossom]

I was wrong and the Luftwaffe did produce and use stereo photographs. The confusion seems to have arisen because the Luftwaffe stressed speedy interpretation and normally worked with negatives which did not allow them to view in stereo Collection Description - Luftwaffe: Aerial Reconnaissance (Scotland). However, before parachute attacks for example, stereo images were examined in great detail Airborne Operations in World War II: A German Appraisal - Hellmuth Reinhardt - Google Books.

 

[Ivan1GFP]

To change the subject yet again, this is lifted from a post by Charles Bronson in the Weapons Systems forum:

Breda SAFAT 12,7mm guns - A real life account of their real power - Official 1C Company forum

Apparently the 12.7 mm explosive shells in the Italian guns and probably the Japanese ones as well were quite a bit more effective than one would expect from something that small.

- Ivan.