Hs-129: asset or liability; alternatives?

[dedalos]

Looking for an imroved Hs 129, with reasonable modifications but requiring some better co operation between germany and japan, what about using Nakajima sakae 21. The zero s engine.Reasonably heavier than the original engines (170kgr), reasonably wider (1150mm vs 950 mm diameter), and 430 hp more powerful.
Plus the potential to use ADI. on Paper it appears perfect
Generally japan had some pretty good radials. Especially the Homare beats BMW801D on every sector,despite using inferior fuel!

 

[tomo pauk]

The Fiat A.74 might be a closer alternative, in geography, weight and time. ~150 kg heavier than the G&R 14M, 840-960 CV power; a bit wider, though. Italians can come out with a S/C gearing of lower ratio, should provide even more power on low altitudes.
But then, unless the Hs 129 is not outfitted with at least a 5cm cannon, it would be an expensive alternative to the Ju 87G, both to purchase and operate.

 

[Shortround6]

Best alternative are the Italian Isotta-Fraschini air cooled Inverted V-12 engines. At least they are in the same hemi-sphere and don't require shipment by submarine. Weight is closer even if power isn't much different.

 

[kool kitty89]

The Fiat A.74 might be a closer alternative, in geography, weight and time. ~150 kg heavier than the G&R 14M, 840-960 CV power; a bit wider, though. Italians can come out with a S/C gearing of lower ratio, should provide even more power on low altitudes.
But then, unless the Hs 129 is not outfitted with at least a 5cm cannon, it would be an expensive alternative to the Ju 87G, both to purchase and operate.

If you wanted better performance, load carrying potential, and better survivability (including practical single engine performance), going a step further to the Gnome Rhone 14N might make more sense. 9 cylinder BMW or Bramo radials might be considered as well, but they're a bit larger diameter and lower power (without C3 or WM/50 ... or the late BMW 132 models that don't seem to have seen service).

The Isotta Fraschini Delta wouldn't address the power loading issues much (depending on the model), but might reduce drag somewhat. It probably would have been more interesting if used directly as a follow on to the Argus engines in the prototypes in place of the 14M.

For that matter, the Delta is one engine that got overlooked in the recent Fw 187 discussions.

 

[GrauGeist]

...or the late BMW 132 models that don't seem to have seen service)...

The later, more powerful BMW132 was used in at least two types that I am aware of, the Ar196 (BMW132Dc) until 1944 and the Ju52/3Mg7 (BMW132T) until 1945.

The BMW132 (especially the D series) would have been an ideal engine for the Hs129, the B-2 was already set up for radials (700hp) and installing the 132Dc (838hp) or the 132De (868hp) woild have certainly seen an improvement in performance.

 

[Shortround6]

Ok Guys, the Gnome Rhone 14M engine was a tiny engine, not just in power but in size and weight. It was sort of a 3/4 scale 14N.

It was only 950mm in diameter. One of the proposed engines (the BMW 132) is 430mm (16.9in) bigger in diameter. See the 3 view drawing in post #10. Unless you change the thrust line you are going to be dealing with cowls a good 200mm (8in) higher making vision to the sides a bit of a problem. The extra drag is going to kill some of the performance. The extra power is going to handy for lifting a bigger load but the BMW radials have twice the frontal area of the 14m. That makes them bigger targets too.

The Hs 129 wasn't a really big plane, it was big compared to a 109 but.

and this is what it started as

you really want to stick a pair of these on it.

 

[Gixxerman]

I recall reading once that the LW never had more than about 500 Ju87's available at any one time.
Therein (even if only approximately true) lies a lot of the (increasing) problem Germany had, too few against way too many.
Regardless of individual airframe/weapon performance etc.

 

[dedalos]

Ok Guys, the Gnome Rhone 14M engine was a tiny engine, not just in power but in size and weight. It was sort of a 3/4 scale 14N.

It was only 950mm in diameter. One of the proposed engines (the BMW 132) is 430mm (16.9in) bigger in diameter. See the 3 view drawing in post #10. Unless you change the thrust line you are going to be dealing with cowls a good 200mm (8in) higher making vision to the sides a bit of a problem. The extra drag is going to kill some of the performance. The extra power is going to handy for lifting a bigger load but the BMW radials have twice the frontal area of the 14m. That makes them bigger targets too.

The Hs 129 wasn't a really big plane, it was big compared to a 109 but.

View attachment 292636

and this is what it started as

View attachment 292637

you really want to stick a pair of these on it.

View attachment 292638

That a why Sakae would be Ideal for the aircraft. The various altrernative italian engines simply are too weak to make any Real difference
I dont find impossible that germany could get licence to produce the sakae 21. It would be useful for other aircafts too.(ar 196,do 24 etc)

 

[tomo pauk]

In case Germany gets way too much of the G&R 14N engines, stick them on the Ju 87. Using 28 cylinders to have one 30-37mm cannon airborne is rather wasteful. Let alone all the fuel it would've burned to kill a tank or two, maybe. As SR6 noted above, the Hs 129 started with 315 kg light Argus 410 engines.

That a why Sakae would be Ideal for the aircraft. The various altrernative italian engines simply are too weak to make any Real difference
I dont find impossible that germany could get licence to produce the sakae 21. It would be useful for other aircafts too.(ar 196,do 24 etc)

Going with G&R 14M meant that bare engine weight is up by 2 x 100 kg. The wing sweep was 'deleted' in order for CoG to remain in limits. Going with Sakae 21, the bare engine weight goes up by another 2 x 175 kg. Power is there, but what do we gain at the sharp end (= firepower)? The Sakae 21 became available in mid 1942 (?), power was lower with Sakae 11.
The I-F Delta was good for 840 PS, but was 2 meters long - it would be a long shot to install it with CoG remaining in limits. My proposal, the A.74, was much shorter, but again it weights as much as Sakae 21 - 590 kg - too much; max power 960 PS.

I'd rather propose the LW equivalent of the Yak-9T for the LW, maybe based on the Fw-190.

 

[davparlr]

The Hs 129 wasn't a really big plane, it was big compared to a 109 but.

Great Pix. I always thought that plane was way too small to put all the things others have said it could possibly do.

 

[kool kitty89]

It was only 950mm in diameter. One of the proposed engines (the BMW 132) is 430mm (16.9in) bigger in diameter. See the 3 view drawing in post #10. Unless you change the thrust line you are going to be dealing with cowls a good 200mm (8in) higher making vision to the sides a bit of a problem. The extra drag is going to kill some of the performance. The extra power is going to handy for lifting a bigger load but the BMW radials have twice the frontal area of the 14m. That makes them bigger targets too.

Yep, all advantages for the Delta over the 14M as well, save weight. Visibility to the sides should have been closer to the original As 410 configuration, granted the 129's cockpit didn't have the best field of view in general, but still a useful improvement. Plus power was a bit better than the 14M, perhaps a bit better still if the supercharger ratio was changed for the low altitudes the Hs 129 really needed.

The Hs 129 wasn't a really big plane, it was big compared to a 109 but.

Yes, it's very similar in overall size to the Fw 187.

The I-F Delta was good for 840 PS, but was 2 meters long - it would be a long shot to install it with CoG remaining in limits. My proposal, the A.74, was much shorter, but again it weights as much as Sakae 21 - 590 kg - too much; max power 960 PS.

CoG shift would be a problem for the majority of engine changes in question, but yes that's still a useful point. Using a lower altitude supercharger configuration should have helped with maximum power output as well.

I'd rather propose the LW equivalent of the Yak-9T for the LW, maybe based on the Fw-190.

You'd have to make it DB-603 powered to manage a nose mounted cannon or resort to Hurricane IID style underwing pots. (but a BK37 is a good deal larger and heavier than the Vickers S and the Fw 190 has a significantly smaller wing) MK 103 pods might be more practical. (but then, so would a MK 103 nose cannon -and more likely to fit in the airframe than the BK37)

 

[Shortround6]

In case Germany gets way too much of the G&R 14N engines, stick them on the Ju 87.

The G&R 14N pretty much slammed into a brick wall at 1100hp. Even the post war version was only rated at 1180hp for take-off at 2650rpm. the pre-war/1940 versions pretty much being limited to 2360/2400rpm. Junkers started work on the Ju-87D in the Spring of 1940 and not only redid the engine mount/set up to take the Jumo 211J but modified the engine cowl and radiators, redesigned the canopy for less drag, redesigned the landing gear 'trousers' and enlarged the tail. All of this for what was viewed as an "interim' type. Spending engineering time an a Ju-87 variant that would be less capable than the Ju-87B already in production doesn't seem like a good idea even if you can get a bunch of 14N engines. Production of the 87D starting in the spring of 1941 at which point any unit getting G-R powered JU-87s would be wondering what they did to get punished.

The Germans were certainly planning to do something with the G-R engines but plans seem a bit hazy. It was noted that G-R production as a whole was about 25% of what the Germans planned/anticipated. G-R managed to produce just enough to prevent mass reprisals from the Germans or having the bulk of the machinery hauled away.

 

[Shortround6]

When people propose building engines to foreign blueprints (Germans build Japanese engines) they may want to think about doesn't get built. NO country in WW II involved in the fighting had spare engine building capacity going unused. Building several hundred engines for a 'special' project aircraft means several hundred other engines don't get built. The Germans were trying to use the production capabilities of the countries the occupied. In some cases by looting them and sending the machine tools back to Germany to equip new or expanded factories in Germany and in other cases by continuing production of the original engines and in some cases by have the occupied factories built parts for engines that were shipped to German factories for final assembly. In a few cases the occupied factory built complete German engines to either supplement German production or free up the German factory for another project. Argus 411s being built by Renault during the war and production continuing after the war.

 

[tomo pauk]

...

You'd have to make it DB-603 powered to manage a nose mounted cannon or resort to Hurricane IID style underwing pots. (but a BK37 is a good deal larger and heavier than the Vickers S and the Fw 190 has a significantly smaller wing) MK 103 pods might be more practical. (but then, so would a MK 103 nose cannon -and more likely to fit in the airframe than the BK37)

It is of course necessary to make sure that 3cm (or, even better, the 3,7cm, amount of ammo might be the problem) can fit between engine and pilot - the Yak-9T have had the cockpit removed 40cm back so the 37mm can fit. Then, hopefully, the Jumo 211F might be 'persuaded' for the job. 1st - try to see whether it is possible to have the engine cannon feature back, like it was true for the Jumo 211B. 2nd - take advantage of the low compression ratio in order to have the boost up to, say, 1.6 ata (and beyond). Looking at the power chart, it should give 1550-1600 PS on the sea level, ~1400 PS at 1km, and, in second gear, 1350 PS at 3.8 km (all values for 2600 rpm, 1.6 ata and no ram). That would not be power to compete vs. Western air forces, esp above 3 km, but it would come in handy for a fighter bomber of the Eastern front. Add some protection to the coolers. Fit the engine cannon, no fuselage guns of course, and 2cm in the wing roots. The AP shot will also make Il-2 drivers feel uncomfortable, armor protection won't cut against that threat. Such a Fw 190 wont be able to take off with 1800 kg bomb or a torpedo, but lighter bombs should be no problem.

 

[kool kitty89]

It is of course necessary to make sure that 3cm (or, even better, the 3,7cm, amount of ammo might be the problem) can fit between engine and pilot - the Yak-9T have had the cockpit removed 40cm back so the 37mm can fit. Then, hopefully, the Jumo 211F might be 'persuaded' for the job. 1st - try to see whether it is possible to have the engine cannon feature back, like it was true for the Jumo 211B. 2nd - take advantage of the low compression ratio in order to have the boost up to, say, 1.6 ata (and beyond). Looking at the power chart, it should give 1550-1600 PS on the sea level, ~1400 PS at 1km, and, in second gear, 1350 PS at 3.8 km (all values for 2600 rpm, 1.6 ata and no ram). That would not be power to compete vs. Western air forces, esp above 3 km, but it would come in handy for a fighter bomber of the Eastern front.

That engine arrangement seems like it would be attractive for Eastern Front fighters in general, though likely with the MK-103 replaced with the 108 or MG 151 along with reduced armor when not expressly intended for ground attack.

Aside from the Fw 190, there's still some question of the Bf 109, but even given the Yak 9 managing it, repositioning the cockpit might not be practical in the small airframe. (either way, the low-alt Jumo 211F remains interesting, and the 109T's wing would be attractive for fighter-bomber use in general)

Add some protection to the coolers. Fit the engine cannon, no fuselage guns of course, and 2cm in the wing roots. The AP shot will also make Il-2 drivers feel uncomfortable, armor protection won't cut against that threat. Such a Fw 190 wont be able to take off with 1800 kg bomb or a torpedo, but lighter bombs should be no problem.

For anti-armor use, I'd think AP ammo on the 15 mm MG 151 would be more useful.

 

[Shortround6]

Advantage the Russians had was that on the M-105 almost the entire space between the cylinder blocks was clear. Both the intake system and the exhaust was on the outside of the engine.

On the German engines space was made for a tube with a 70mm inside diameter. Which means your barrel cannot exceed 70mm in diameter even if the barrel is in contact with the tube (not a good idea due to cooling and friction. )
For a 30mm gun that means your barrel walls can only be 20mm (or less) thick. Things get real interesting with a 37mm gun. 16mm thick barrel walls? or less?

Now maybe the Germans could have gone back to the drawing board and changed a few things to allow a bigger tube but it is still a tube. Russians only hit a restriction when they get to the propshaft and gear case. last few feet of a barrel can be rather skinny as the pressure is rather low at that point.

 

[Shortround6]

For anti-armor use, I'd think AP ammo on the 15 mm MG 151 would be more useful.

When trying to take out armor the goal is to destroy/kill what is behind the armor, not just poke holes in the armor. The bigger the hole the more 'stuff' (metal that used to be in the 'hole') is flying around inside the vehicle. Even 37-40mm guns often failed to "kill" a tank with 1st or 2nd or even 3rd penetrating hit depending on where it hit. The 15mm is only moving about 56% as much "stuff" as a 20mm. Granted a round that doesn't penetrate at all doesn't do anything.

This is one reason small anti-tank rifles fell out of favor. They often required multiple hits/penetrations to get a "kill" and while better "than nothing" that is faint praise indeed.

 

[GrauGeist]

To add to that, if your in the air attacking armor, you only have a small window to aquire and hit your target. Needing multiple hits for a kill means perhaps several passes.

All this time, you have the sole undivided attention of ground forces who are not very happy at your presence.

 

[kool kitty89]

Advantage the Russians had was that on the M-105 almost the entire space between the cylinder blocks was clear. Both the intake system and the exhaust was on the outside of the engine.

An unusual feature (flathead engines aside) shared by the Hispano-Suiza 12Y.

On the German engines space was made for a tube with a 70mm inside diameter. Which means your barrel cannot exceed 70mm in diameter even if the barrel is in contact with the tube (not a good idea due to cooling and friction. )
For a 30mm gun that means your barrel walls can only be 20mm (or less) thick. Things get real interesting with a 37mm gun. 16mm thick barrel walls? or less?

Did the space provided on the DB 603 increase that at all?

When trying to take out armor the goal is to destroy/kill what is behind the armor, not just poke holes in the armor. The bigger the hole the more 'stuff' (metal that used to be in the 'hole') is flying around inside the vehicle. Even 37-40mm guns often failed to "kill" a tank with 1st or 2nd or even 3rd penetrating hit depending on where it hit. The 15mm is only moving about 56% as much "stuff" as a 20mm. Granted a round that doesn't penetrate at all doesn't do anything.

I was more referring to the Il-2 comment. For anti-armor I'd think the MK-103 would be the minimum, maybe the MG c/30L would have been usable on lighter armor (more so early-war).

 

[Shortround6]

The Germans were working on a version of the MK 103 to fit in the 70mm tube.

View attachment 292764

This is the regular version. A bit shorter or longer barrel may not have been a big problem. Reducing the size of the barrel support and position of the gas tube would take more work. There was an awful lot of gun behind the 70mm tube if they didn't.

The problem with shooting down the IL-2 was getting a good firing angle on the armor. A lot of the armor was 4-6mm thick? but the impact angles were very shallow causing the projectiles to ricochet off. See: MG 151 cannon - Wikipedia

Germans had four different kinds of AP ammo for the MG 151/20. how wide spread some where may be subject to question.

As for the high angle impact problem see this chart from originally posted here. http://www.ww2aircraft.net/forum/we...ftwaffe-cannons-machineguns-topic-6368-5.html

Not all projectiles behave the same but impact angles of less than 30 degrees to the surface of the plate get even more difficult.