The Hs 129 idea done 'right', and for everyone

[Shortround6]

German 15mm with steel projectile (72 g at 850 m/s) was good for 25mm or armor at 90 deg impact and at 300m. The Pz-I and -II is a fair game, while the Pz-III or IV will require an ideal hit from behind - not somthing we can count on.

"Bullet weight was 1160 grains (75 grams)and the propellant charge was 325 grains of Cordite for the W Mark I and 370 grains of nitro-cellulose for the W Mark Iz.Velocity at 90 feet was 2,900 feet per second (883m/s) at a maximum mean pressure of 22 tsi and penetration was seven out of ten shots must penetrate 27mm armour plate at 100 yards."

Pz 35 (t) 25mm armor on the front. 15/16mm armor on the sides and rear.
Pz 38 (t) 25mm armor on the front. 15/16mm armor on the sides and rear. The versions with more armor don't leave the factory until Nov 1940
Pz IIIE in France had 30mm front and sides, rear of turret was 30mm, hull was 21mm. Any of the older versions with 14.5/15mm armor had been taken out of service in Feb 1940.
Pz IV B&C had 30mm front as built and 15mm sides and rear. some were up armored before France but not everywhere.
Pz IV D had 30mm front as built and 20mm sides and rear but again, not all were unarmored and not all got 100% coverage of up armoring (some were far from it).

British knowledge of the up armoring??

It is not ideal, it is what you have and the alternatives need more work (heck the 15mm may need work for aircraft mounting)

Ro.57 was eventually rated for a 1000 kg bomb, the Hs 129 for a 7.5cm cannon - I'd say that these compact aircraft were substantial enough for 37mm artillery
Hurricane carried two 40mm guns, that were much more powerful than the 2 pdr pom-poms.

Yes and no.
The Vickers 2pdr used in aircraft used a much longer recoil stroke than the 2pdr pom-pom. The peak recoil loads were less than a 20mm Hispano. The 2pdr Vickers delivered more total recoil but it was spread out over a longer period of time.

The Pak 7.5 cm AT gun recoiled over 1 meter in distance. Spread the recoil out so the gun didn't bounce around all over the place on it's wheels. The Tank cannon with about the same recoil only recoiled about 30-40CM (?) but you had a 20-25 ton vehicle keeping it in place. It also only a few shells per flight.

I don't know about the French 37mm, the Italian 37mm AA gun was noted for poor accuracy because it vibrated the deck mount/plates.

Not all guns are adaptable for aircraft use without a lot modification.

 

[tomo pauk]

British knowledge of the up armoring??

It is not ideal, it is what you have and the alternatives need more work (heck the 15mm may need work for aircraft mounting)

British don't know the exact armor thickness of German tanks in the 1st place. They do know that vast majority of French tanks have armor topping 40mm well before ww2, and can expect that Germans will try and match it.
Going with a more substantial gun = better safe than sorry.

Yes and no.
The Vickers 2pdr used in aircraft used a much longer recoil stroke than the 2pdr pom-pom. The peak recoil loads were less than a 20mm Hispano. The 2pdr Vickers delivered more total recoil but it was spread out over a longer period of time.
The Pak 7.5 cm AT gun recoiled over 1 meter in distance. Spread the recoil out so the gun didn't bounce around all over the place on it's wheels. The Tank cannon with about the same recoil only recoiled about 30-40CM (?) but you had a 20-25 ton vehicle keeping it in place. It also only a few shells per flight.
I don't know about the French 37mm, the Italian 37mm AA gun was noted for poor accuracy because it vibrated the deck mount/plates.
Not all guns are adaptable for aircraft use without a lot modification.

There will be a lot of work indeed. Better start with it ASAP so the workable firepower is to be had by 1939.

 

[GrauGeist]

The BK7.5 was a bit much for the Hs129 to heft around, though.

The BK3.7 did produce solid results against targets and weighed less, allowing for more stable flight.

I am surprised that the Luftwaffe didn't consider the BK5 as an option, though they did use it mounted in Me410s for anti-bomber operations.

BK7.5 weighed 1,554 pounds.
BK3.7 weighed 650 pounds.
BK5 weighed 1,190 pounds.

 

[wiking85]

Hs 129 was a result of specification that required a small 2-engined aircraft, powered by 'non-strategic' engines (ie. by the engines not required for the 1st line A/C), well armored, and with some meaningful firepower.
(the non-strategic engine part was flawed IMO - once you must manufacture two engines per A/C, and the total HP provided is lower than on a single 'normal' engine, while needing two propellers, two oil systems, that math falls in the water, but I digress)
Let's change the spec a bit, and apply it for other countries, too. Still a small 2-engined A/C is required, well armored, with very good firepower, preferably 1-seater, engines in question are preferred to be of non-strategic type, but without going into extremes so the AC is under-powered, IOW no need to go for 400-600 HP engines. Good guns' firepower is needed, so is the carriage of a lot of small bombs. No bomb bay is required.
Yes, some air forces don't have a thing for tactical A/C that much, let's have that changed for the purposes of this thread.
Aircraft needs to be in service by early 1940 in it's 1st version.

Simply, just build the HS123C en masse.

 

[tomo pauk]

Simply, just build the HS123C en masse.

Hs 123 does not apply - topic is about 2-engined attackers.

 

[wiking85]

Hs 123 does not apply - topic is about 2-engined attackers.

At a certain point you have to think outside the box to arrive at the right design.
But if you absolutely insist on 2 engines I'd say save DB601/5s from the DB606/10 project (which should have been cancelled) and instead build the Me109Z:

Me 109 Zwilling

This experimental aircraft was essentially two Bf 109F airframes joined together by means of a new wing centre section and new tailplane, both of constant chord. In the preproduction model, the...

www.nevingtonwarmuseum.com

Would have had all the necessarily firepower and hauling capabilities to conduct ground attack missions and ability to replace the Bf110, while increasing production overall from economies of scale.

If you insist on the non-strategic engines, then modify the fuselages to handle the Hs123's engine the HS132, but the late version W-series with about 1000hp.

Or a HS123Z...

 

[tomo pauk]

But if you absolutely insist on 2 engines I'd say save DB601/5s from the DB606/10 project (which should have been cancelled) and instead build the Me109Z:
Would have had all the necessarily firepower and hauling capabilities to conduct ground attack missions and ability to replace the Bf110, while increasing production overall from economies of scale.

Me 109Z is many times a very good suggestion. Would not be out of place here, too. A bit better armor protection should come in handy. I'd definitely go with both fuselages being 'populated' (as always for the 109Z IMO).
Another change that I'd make is having one pair of stronger U/C members vs. two pairs of historical U/Cs - saves internal volume, as well as some weight.

 

[mack8]

For what it's worth, i have read that there was a Henschel P76 project which was a slightly larger Hs-129 but with BMW-132 engines. So more power would be good, and as i understand the 132 was reliable while the 14M not so much.

 

[GrauGeist]

The Hs129B series was a result of the P.76 proposal, with the G-R 14M replacing the Argus 411 engines.

The Hs129C/D was planned to have either inlines or BMW801 radials.

 

[Howard Gibson]

Hs 129 was a result of specification that required a small 2-engined aircraft, powered by 'non-strategic' engines (ie. by the engines not required for the 1st line A/C), well armored, and with some meaningful firepower.
(the non-strategic engine part was flawed IMO - once you must manufacture two engines per A/C, and the total HP provided is lower than on a single 'normal' engine, while needing two propellers, two oil systems, that math falls in the water, but I digress)
Let's change the spec a bit, and apply it for other countries, too. Still a small 2-engined A/C is required, well armored, with very good firepower, preferably 1-seater, engines in question are preferred to be of non-strategic type, but without going into extremes so the AC is under-powered, IOW no need to go for 400-600 HP engines. Good guns' firepower is needed, so is the carriage of a lot of small bombs. No bomb bay is required.
Yes, some air forces don't have a thing for tactical A/C that much, let's have that changed for the purposes of this thread.
Aircraft needs to be in service by early 1940 in it's 1st version.

I figure the Hs 129 had the success it did because it operated on the Russian Front. If they had flown these things in Normandy, they would have been quickly and efficiently massacred. Use the biggest engines possible.

How about the tiniest aircraft possible, built around two BMW801s, and the BK7.5?

 

[tomo pauk]

How about the tiniest aircraft possible, built around two BMW801s, and the BK7.5?

Focke Wulf was pitching the BMW 801-powered Fw 187 in the same time they were making a pitch for a DB 605-powered version. Former was some 530 kg heavier empty than the later. Both were also supposed to carry up to 2000 kg worth of bomb, as well as to be outfitted with 4 cannons, as well as with two rear-firing MG 131s.
BMW-powered 187 was supposed to weight 8730 kg with 1000 kg of bombs, and another 1000 kg more with 2000 kg (doh).

So this is probably the tiniest aircraft that fits the description. Also makes P-47N not that heavy in comparison

 

[Howard Gibson]

Hs 129 was a result of specification that required a small 2-engined aircraft, powered by 'non-strategic' engines (ie. by the engines not required for the 1st line A/C), well armored, and with some meaningful firepower.
(the non-strategic engine part was flawed IMO - once you must manufacture two engines per A/C, and the total HP provided is lower than on a single 'normal' engine, while needing two propellers, two oil systems, that math falls in the water, but I digress)...

You missed the the part about how the engines were made by people who want you [edit] to die, die, die!. There were quality issues.

 

[tomo pauk]

You missed the the part about how the engines were made by people who want to die, die, die!. There were quality issues.

Not in 1940-41.

 

[Howard Gibson]

Hs 129 was a result of specification that required a small 2-engined aircraft, powered by 'non-strategic' engines (ie. by the engines not required for the 1st line A/C), well armored, and with some meaningful firepower.
(the non-strategic engine part was flawed IMO - once you must manufacture two engines per A/C, and the total HP provided is lower than on a single 'normal' engine, while needing two propellers, two oil systems, that math falls in the water, but I digress)
Let's change the spec a bit, and apply it for other countries, too. Still a small 2-engined A/C is required, well armored, with very good firepower, preferably 1-seater, engines in question are preferred to be of non-strategic type, but without going into extremes so the AC is under-powered, IOW no need to go for 400-600 HP engines. Good guns' firepower is needed, so is the carriage of a lot of small bombs. No bomb bay is required.
Yes, some air forces don't have a thing for tactical A/C that much, let's have that changed for the purposes of this thread.
Aircraft needs to be in service by early 1940 in it's 1st version.

By 1944, the Americans and British used aircraft for ground attack that had the performance to look after themselves. The Ju87s and Hs129s were not used in the ETO in 1944 because the Germans could not assure the air superiority needed for their survival. The RAF Battles and Blenheims were massacred in 1940, so this point was becoming apparent even them.

Okay, the problem is not obvious in 1937 when you start designing.

Apparently, around half of all aircraft lost by the Americans in Vietnam were brought down by small arms fire. The reasoning behind the Fairchild A10 is that if can withstand small arms, you eliminate half your losses. If the A10 gets hit with concentrated 20, 23 or 37mm cannon fire from six o'clock, or by 40mm flak, it is going down. There is only so much you can do with armour. Cecil Adams of The Straight Dope has been asked about this...

If aircraft "black boxes" are indestructible, why can't the whole plane be made from the same material?

Are BMW 132s strategic engines?

The Hs129s did not reach service until 1942, late enough that they could use French engines. It was in the MTO. I have the Profile publication here, and it is not clear on how effective they were when they somehow reached combat. Aeroplane engines must be built by people who like you. On the Russian front, they had effective escorts, especially early in the war.

Okay, we build the single seat Baconator 400. It is powered by two BMW 132s for a total of around 1500HP. It is heavily armored. It can do 250mph, or 400kph, hence its name. Given effective support by Luftwaffe fighters in 1939/40, it will do well in the Blitzkrieg. If it is caught without escort, or it is attacked by fighters powered by 100_octane fuel, it will be shot down.

 

[Shortround6]

You missed the the part about how the engines were made by people who want to die, die, die!. There were quality issues.

Depends on when. The Argus engines were built in Germany by non-slave labor, but the engines were too small.
Seemed to work OK in the Fw 189.

The engines used in bulk of the Hs 129s were French engines and there were a bunch of reasons for the problems.
1. the design flaw of using two bearings on a two throw crank.
2. a lot of the engines were 'Used' having been pulled off of existing French aircraft sitting in parks/dumps. Overhaul status????
3. New engines were built by French workers who were trying to do as little as possible without getting shot/sent to Russian front as construction workers.
A fine line being being just useful enough to keep and being slave labor on the Russian Front (or somewhere in-between). Reprisals against friends and familiar were also a possibility.
4. any other flaws in the engine design itself? G-R got a lot of French contracts because the only competitor, Hispano-Suiza radials, had engines that tended to have propellers fall of in flight.
Better reliability was a low bar.

 

[bf109xxl]

Here's what you get with two 140 hp engines:

2x23mm, 500kg bomb load, 167kph

And here's what you get with two 1,000 hp engines:

4x20mm, 2x37mm, 2x7.62mm, up to 1600 kg bomb load, 513kph

And here's what you get with two 2,000 hp engines:

4x45(37)mm, 6x7.62mm, 1x12.7mm, up to 1400 kg bomb load (normal 600kg), 552kph

The armoring of the mentioned aircraft differs significantly.
But from my point of view, the concept of a heavily armored attack aircraft has demonstrated its unsuitability for both twin- and single-engine aircraft.

 

[tomo pauk]

Okay, we build the single seat Baconator 400. It is powered by two BMW 132s for a total of around 1500HP. It is heavily armored. It can do 250mph, or 400kph, hence its name. Given effective support by Luftwaffe fighters in 1939/40, it will do well in the Blitzkrieg. If it is caught without escort, or it is attacked by fighters powered by 100_octane fuel, it will be shot down.

Like the Baconator.

 

[Shortround6]

The RAF Battles and Blenheims were massacred in 1940, so this point was becoming apparent even them.

Well, it took quite a while for the RAF to figure out that fighter escort for strike or CAS aircraft meant that the fighters were actually supposed to at least catch a glimpse of the bombers during the mission. Scheduling a fighter sweep through the same area give or take 30 minutes of the scheduled bomber strike was NOT escorting the bombers.

The other thing was the continual improvement of AA defenses.

German use of a Polish LMG for AA use. The Poles had very little else other than the BAR version.

For those people that like what ifs, The US Army was planning on using BARs for AA defense at least until the summer of 1940. Crossed over with the 1919 Browning. While the Navy was using .50 cal Brownings on ships (water cooled) the Army didn't really start using them until 1941/42, in part due to starting up mass production.

Self sealing tanks and a bit of armor would improve things against rifles or rifle caliber guns and again, the British were among the first to build armored attack aircraft. The Sopwith Salamander. Wiki
"Work on a more advanced armoured fighter, conceived as an armoured version of the Sopwith Snipe, began early in 1918. The forward portion of the fuselage was a 605 lb (275 kg) box of armour plate, forming an integral part of the aircraft structure, protecting the pilot and fuel system, with a 0.315 in (8 mm) front plate, a 0.433 in (11 mm) bottom plate, 0.236 in (6 mm) side plates and rear armour consisting of an 11-gauge and 6-gauge plate separated by an air gap"

War ended before service use.

 

[yulzari]

Perhaps a bit too much emphasis here on armour piercing. With the S Gun one gets a decent HE round which proved useful in Burma and may be better suited to the CSA role generally than a dedicated smaller hole puncher and we know it does work in all directions of G forces with the S Gun drums. Twin S Gun in a Mercury/Perseus Whirlwind?

 

[GrauGeist]

One of the first purpose built ground attack aircraft, was the Junkers J.I, which went into service in 1917.