"Jumo 222" and "DB 606/610" made in H16 form instead of being 24 cyl types - what gives?

[tomo pauk]

Basically, both engines are designed in the shape similar as the Napier or Fairey engines, where we can take about the separate engines one atop of the other (or one aside to the other - whatever floats your boat), that share supercharger and propeller, as well as other bits and pieces so that pilot, for all intents and purposes, directs the power of just one compete engine.
Engine bore and stroke are shared with the mass-produced types, Jumo takes from the 211, DB takes from the DB 601/605. Contemporary advantages and disadvantages of German engines are present here, like the direct fuel injection, can make decent power on 87 oct fuel due to the engines being of reasonably big displacements, while the lack of nickel and, with DB , quirky oil system are also in play. Both engines are obviously liquid cooled
Development of both engines start as it was the case historically, in the late 1930s, with the DB contender making the 1st flights in the early 1939, and the Jumo's engine doing the same in the early 1940.

What changes to the German design and purchase might've unfolded with these engines available in good numbers, both wrt. the next-gen aircraft and next-gen engines?

 

[Shortround6]

They might solve the bomber engine problem. Quick way to get 33% more power using existing technology ( cylinder size X power per cylinder)

Problems are greater weight per HP and greater frontal area. More important to a fighter than to bomber. View from cockpit on a fighter is also going to suck.
Perhaps the shorter crankshafts can be a bit lighter than just sawing off a 6 throw crank, and the cylinder blocks can be a bit lighter but you are trading two cylinder blocks and heads for 4 cylinder blocks/heads.

On bombers the weight and frontal area of the engines are a smaller percentage of the overall weight and drag.

For DB we are looking at a 45.22 liter engine compared to the 44.5 liter DB 603. Not sure if the extra cost/complexity is worth it.
For Junkers almost anything was better than getting involved with the 222 (46.5 liters in early versions) engine in hindsight.
Jumo H-16 comes out at 46.5 liters
But the H-16 Jumo is not going to promise the small diameter and high rpm of the 222.

I can see Junkers going for the H-16 as an quick easy alternative to the Ju 222 and/or trying to get the 211 to run faster than 3000rpm.
DB just sat on the 603 for a while but one has got to ask, was it more difficult to make an H-16 ( vibration and layout problems) than it was to get the 603 to run at 601 speeds at the same point in time?

 

[wuzak]

Why not use the full 6 cylinder banks of the original engines for an H-24?

This was done by Arsenal 24H post war with cylinder blocks of the Jumo 213.

Power output for a Jumo 211 H-24 would be around 2,300-2,400hp. Dry weight ~ 1,280kg/2,800lb.

Doing the same with a DB 601 would give power about the same as a DB 606 (ie, ~2,700hp). Using a single supercharger and accessory drive would save weight.

 

[don4331]

S Shortround6 : You should be leading with your standard - the initial issue is cooling: the Jumo 210 and 211A-D aren't pressure cooled, so they are limited to ~25 kW/l. Note: the Jumo 211D is only turning 2,400 rpm.

The Jumo 222 is trying for 40 kW/l - it just isn't going to work in planned the timeframe. The Luftwaffe is wanting 2,500 to 3,000 hp - you better think big!

W wuzak : I saw your response just after I posted but your 2 x Jumo 211D of 70l is the right size. My 2 x Jumo 210G was too small.

With that size, you're going to have a lot of the same issues as DB606 had...

 

[tomo pauk]

Why not use the full 6 cylinder banks of the original engines for an H-24?

2 reasons:
H16 engines were very rare.
24 cyl engines were not suitable to be retrofitted on existing aircraft due to size and weight of these engines; Ju 288C notwithstanding.

 

[tomo pauk]

For Junkers almost anything was better than getting involved with the 222 (46.5 liters in early versions) engine in hindsight.
Jumo H-16 comes out at 46.5 liters
But the H-16 Jumo is not going to promise the small diameter and high rpm of the 222.

I can see Junkers going for the H-16 as an quick easy alternative to the Ju 222 and/or trying to get the 211 to run faster than 3000rpm.

Looking at the stroke of big radials, the 55.3 in wide & tall Centaurus was with the 178 mm stroke, so perhaps the Jumo and DB engines with 165 and 160 mm stroke are not to generate such a tall engine. With pistons moving vertically, they will also be less wide than the powerful radials, and thus easier to streamline than these. We'd probably be getting ~1000 kg engines from both DB and Jumo intially.
Curiously enough, the Jumo 213 was a less tall engine than the 211, despite sharing the stroke and the same basic layout.

Cheating a little bit - making the new versions having shorter stroke should give them an 'access' to the 3000 rpm operation and will result in less tall engines, while keeping both the piston speed and weight in check. The Jumo H16 is certainly an alternative to the 222.

For DB we are looking at a 45.22 liter engine compared to the 44.5 liter DB 603. Not sure if the extra cost/complexity is worth it.

DB just sat on the 603 for a while but one has got to ask, was it more difficult to make an H-16 ( vibration and layout problems) than it was to get the 603 to run at 601 speeds at the same point in time?

DB having a H16 engine in the works might kill both the DB 606 early on (so the He 119 uses two separate engines, and the He 177 looks like something else) and by default the 610, as well as the DB 603. So the company has just 1.5 lines of engines to debug, rather than 2.5 lines; number of engine lines is a pure whim on my part.

Now that I'm talking about the alternative aircraft to use these engines:
- He 177 indeed looks nothing like it looked before, but it is made either as a normal 4-engined bomber, or with two push and two pull engines
- Ju 288 can have a suitable engine, thus it is not stillborn
- Do 217 is not underpowered
- H16 engine might be a good fit on the Fw 190
- there are more BMW engines to spare, since they are not used to save a number of important types in 1942-43, so Ju 88 can have more of these, and He 111 can also get them

 

[Shortround6]

Looking at the stroke of big radials, the 55.3 in wide & tall Centaurus was with the 178 mm stroke, so perhaps the Jumo and DB engines with 165 and 160 mm stroke are not to generate such a tall engine. With pistons moving vertically, they will also be less wide than the powerful radials, and thus easier to streamline than these. We'd probably be getting ~1000 kg engines from both DB and Jumo intially.
Curiously enough, the Jumo 213 was a less tall engine than the 211, despite sharing the stroke and the same basic layout.

the radials are just a tiny bit shorter due the odd number of cylinders. Not much
The French Arsenal H 24 turned out to be 59 in (1.5 meters) tall and 47.2 in (1.2 meters wide and while a 211 version would be lighter (and an H-16 a lot lighter) I don't think there is much you can do about the size (height and width). A little bit yes, the injector pumps stuck up higher than the valve covers and perhaps the width included the engine mount bosses? Maybe the use of two separate supercharges wasn't the best use of space?

You might be able to stick it in a fighter but you need a Typhoon, Tempest, P-47 size fighter.
For a twin engine bomber it does have possibilities.
Problem with replacing the DB 606 with the H-16 is that it has 2/3rds the displacement/power at any give level of development. They maybe able to make up some of that or maybe the H-16 is a bit light per HP than the DB 606 layout.

Cheating a little bit - making the new versions having shorter stroke should give them an 'access' to the 3000 rpm operation and will result in less tall engines, while keeping both the piston speed and weight in check. The Jumo H16 is certainly an alternative to the 222.

Prop is 10.5ft (3.2 meters)
H-16 can use a lot smaller radiator.
Left over radials are R-1830s.

 

[tomo pauk]

Problem with replacing the DB 606 with the H-16 is that it has 2/3rds the displacement/power at any give level of development. They maybe able to make up some of that or maybe the H-16 is a bit light per HP than the DB 606 layout.

There will be no replacing the DB 606 on the aircraft on 1:1 basis, as covered above:

- He 177 indeed looks nothing like it looked before, but it is made either as a normal 4-engined bomber, or with two push and two pull engines

Prop is 10.5ft (3.2 meters)
H-16 can use a lot smaller radiator.
Left over radials are R-1830s.

Tiny prop there - it will hardly suffice on a single Jumo 213, despite having 5 blades?
The 24H does not look like out ordinary there.

BTW - German H16 engine that I'm aware, the DVL's design (that probably never amounted to even a single cylinder test mule) was with the raised prop shaft. Here is in a tandem configuration, two H16s making an H32.
This will improve the ground clearance for the prop.

 

[wuzak]

2 reasons:
H16 engines were very rare.
24 cyl engines were not suitable to be retrofitted on existing aircraft due to size and weight of these engines; Ju 288C notwithstanding.

I wouldn't expect the H24 to be retrofitted into aircraft.

It would be in aircraft that historically were designed around the Jumo 222, DB 606, etc. So He 177, Ju 288 (designed around Jumo 222, ended up with DB 606 and then DB 610 engines).

The H-24s gives the power that the double vee 24 engines had, the H16 doesn't.

A H24/601 should give the He 177 the same power with less fire risk!

A H16 using DB 601 cylinders will have the same frontal area as a H24. The H24 can use the cylinder blocks and crankshafts as is used on the V12, the H16 needs new cylinder banks and crankshaft.


Also, rareness isn't a reason to develop an engine.

 

[wuzak]

DB having a H16 engine in the works might kill both the DB 606 early on (so the He 119 uses two separate engines, and the He 177 looks like something else) and by default the 610, as well as the DB 603. So the company has just 1.5 lines of engines to debug, rather than 2.5 lines; number of engine lines is a pure whim on my part.

Daimler Benz were also developing the DB 609 V16 based on DB 603 cylinders and the DB 613, a coupled DB 603 along the lines of the DB 606/610. They even had a proposed coupled DB 609.

Also, they had the DB 604 X-24 under development early in the war. That was capable of around 2500hp.

With its shorter stroke, it might have made for a more compact H24 than DB 601 or DB 605 if they decided to change the layout (would probably need a new crankshaft design, though).

 

[tomo pauk]

I wouldn't expect the H24 to be retrofitted into aircraft.
It would be in aircraft that historically were designed around the Jumo 222, DB 606, etc. So He 177, Ju 288 (designed around Jumo 222, ended up with DB 606 and then DB 610 engines).
The H-24s gives the power that the double vee 24 engines had, the H16 doesn't.
A H24/601 should give the He 177 the same power with less fire risk!
A H16 using DB 601 cylinders will have the same frontal area as a H24. The H24 can use the cylinder blocks and crankshafts as is used on the V12, the H16 needs new cylinder banks and crankshaft.
Also, rareness isn't a reason to develop an engine.

Daimler Benz were also developing the DB 609 V16 based on DB 603 cylinders and the DB 613, a coupled DB 603 along the lines of the DB 606/610. They even had a proposed coupled DB 609.
Also, they had the DB 604 X-24 under development early in the war. That was capable of around 2500hp.
With its shorter stroke, it might have made for a more compact H24 than DB 601 or DB 605 if they decided to change the layout (would probably need a new crankshaft design, though).

As you can probably discern from my posts above, I'm not very fond on the 24 cyl engines that share genes with reasonably big V12s. One of the reasons for a thread about the H16 types.

 

[Shortround6]

Tiny prop there - it will hardly suffice on a single Jumo 213, despite having 5 blades?

Well, they had to fit it on the existing airframe. Even with 5 blades it was not big enough to handle the power of the 24 cylinder engine.

Just tying to give a context of the size. It is roughly the size (diameter) of an R-2800/R-3350/Centaurus but a little skinner.
The 211 H-16 is 46.7 liters (2847cu in) so it is not a surprise. Frontal area of the R-2800 is 15.2 sq ft, frontal area of the Arsenal H 24 is 14.1 sq ft.

 

[tomo pauk]

Just tying to give a context of the size. It is roughly the size (diameter) of an R-2800/R-3350/Centaurus but a little skinner.
The 211 H-16 is 46.7 liters (2847cu in) so it is not a surprise. Frontal area of the R-2800 is 15.2 sq ft, frontal area of the Arsenal H 24 is 14.1 sq ft.

The 'no free lunch' rule applies as ever - if you want more power, prepare to pay in size+weight, unless you want to risk it with a bespoke design, that might and might not mature fast enough.

 

[wuzak]

What's the advantage of a H-16 engine of 46.7L (Jumo 211 based) against the Jumo 213 of 35L and DB 603 of 44.5L?

The Jumo 211-H16 is going to give around 1,600hp. It will be shorter than the V-12s, but taller and wider. Weight?

A Jumo 211-H24 gets you into the 2,000hp engine class. Which is what the larger German aircraft needed.

For fighters, the V12s still seem the better option.

 

[tomo pauk]

What's the advantage of a H-16 engine of 46.7L (Jumo 211 based) against the Jumo 213 of 35L and DB 603 of 44.5L?

Against the Jumo 213 - timing is better, and the "Jumo 213H16" can also be made, for 2300+ HP.
Against the DB 603 - avoids reliability problems the DB 603 had in all of 1943 and a bit in 1944.

The Jumo 211-H16 is going to give around 1,600hp. It will be shorter than the V-12s, but taller and wider. Weight?

Using the Jumo 211s as the rule of thumb, it is indeed 1600 HP, but for 1940. For 1942, 1800-1900 HP (cue Jumo 211F/J of 1340/1420 PS), and for 1943/44 1900-2000 PS (cue 211N/P). All of this is before the RPM is upped to 3250 rpm, as in case with the Jumo 213, and all with 87 oct fuel, without the swirl throttle and without MW 50. Even 3000 rpm will be good.

I'd expect the weight of around 850 kg for the earlier versions, and around 1000 kg for the later versions that are still based on the historical 211.

A Jumo 211-H24 gets you into the 2,000hp engine class. Which is what the larger German aircraft needed.

It gets you into the 1300 kg engine class, that can't be retrofitted on just about any aircraft that is in series production - a thing that was true for the other 24 cyl engines that shared genes with the series-produced V12s or the 14 cyl radials. It also means that a 2400-3000 HP engine needs to have a big enough a propeller, and that the undercarriage has heaps of strength.
IOW - one must design a bespoke aircraft for a 1300 kg engine, and must pray that engine is a viable type, since it is likely that there is no drop-in replacement.

Staying with engines of under 1000 kg means that a heavy bomber (or more of them) is designed around the 4 (or more) separate engines.

For fighters, the V12s still seem the better option.

Again, the timing is crucial. An H16 in 1943 can be making 2000 HP on 87 oct fuel. Even if the supercharger is not perfect, a decent 1-stage S/C on such an engine will still provide about 1600-1650 PS at 5.7 km, using the 211N and the restricted DB 605A as the rules of thumb.
Using the fully rated 605A (winter of 1943/44), it is about 1750 PS at 5.7-6 km.
Install the high-capacity superchargers (as the 605AS engines had, if not the 2-stage units), and/or swirl throttle, and/or MW 50 system, and there are heaps of power for 1944, while the engine is still not a bloated one. High RPM version, short-stroke version (for the even greater RPM and lower height) ...

 

[z42]

Also, rareness isn't a reason to develop an engine.

Well, it's certainly possible one is stumbling upon a great concept that history for various reasons has overlooked, but more likely people have looked at it in the past and found it wanting.

 

[z42]

In general, I'm not particularly impressed by the H16 layout for an aero engine. You pay a significant cost in complexity, weight, and frontal area and gain only 4 cylinders and a slightly shorter block than the well-trodden path of V-12s. If you're going to go through all the trouble of developing such an engine, at least make it a H24 to provide a significant leap over the V-12s.

In retrospect, IMHO Germany should have focused on improving their V-12s. Like solving the valve and bearing issues, improved (multi-stage) superchargers, making them in general sturdy enough to fully utilize the capability of C3 fuel, etc. Forget all the X, H, W (coupled V's), V-16 etc. Spend the "ooh shiny" budget on turbines. If two 603s or 213's (or 801's if we include radials in this scenario) aren't enough on a big plane, put four of them in a tractor config ahead of the wing like the rest of the world.

 

[tomo pauk]

In general, I'm not particularly impressed by the H16 layout for an aero engine. You pay a significant cost in complexity, weight, and frontal area and gain only 4 cylinders and a slightly shorter block than the well-trodden path of V-12s. If you're going to go through all the trouble of developing such an engine, at least make it a H24 to provide a significant leap over the V-12s.

Ability of a 24 cyl engine, that is long and at ~1300 kg, to be trouble-free retrofitted on an established aircraft design is close to zero. So I'd stay clear from it, and where the loads of power are required, as in the case of really big bombers, use 4 engines.

Weight and size of a 16 cyl engine allows it to be retrofitted on an existing airframe much easier. Hence this thread.
In case of Germany, the retrofit might've made sense on a Fw 190, Ju 88/188/288/388, Do 217, even on the He 111 and Ju 87.

In retrospect, IMHO Germany should have focused on improving their V-12s. Like solving the valve and bearing issues, improved (multi-stage) superchargers, making them in general sturdy enough to fully utilize the capability of C3 fuel, etc. Forget all the X, H, W (coupled V's), V-16 etc. Spend the "ooh shiny" budget on turbines. If two 603s or 213's (or 801's if we include radials in this scenario) aren't enough on a big plane, put four of them in a tractor config ahead of the wing like the rest of the world.

A H16 spin-off is still very useful even under the historical conditions of German having very restricted access to the (for them) rare metals that made them a lot of problems, as well as with S/Cs at the historical level.
The improvements in valves, bearings, S/Cs and ability to withstand greater boost levels can also be siphoned to the H16 engines, meaning heaps of power when everything is said and done, while still doing well with the fuel that Germans had the most - the 87 octane.

 

[z42]

Ability of a 24 cyl engine, that is long and at ~1300 kg, to be trouble-free retrofitted on an established aircraft design is close to zero. So I'd stay clear from it, and where the loads of power are required, as in the case of really big bombers, use 4 engines.

Weight and size of a 16 cyl engine allows it to be retrofitted on an existing airframe much easier. Hence this thread.
In case of Germany, the retrofit might've made sense on a Fw 190, Ju 88/188/288/388, Do 217, even on the He 111 and Ju 87.

Yes, a H-24 would absolutely be a thing for next-generation aircraft. Unless you go for a "Sabre on steroids" approach with small volume and high rpm (forget the sleeve valves though!)?

But I suspect if you can't fit a bigger V-12 like the 603, you won't be able to fit a H-16 either. And the V-12 is a much less riskier proposition.

A H16 spin-off is still very useful even under the historical conditions of German having very restricted access to the (for them) rare metals that made them a lot of problems, as well as with S/Cs at the historical level.
The improvements in valves, bearings, S/Cs and ability to withstand greater boost levels can also be siphoned to the H16 engines, meaning heaps of power when everything is said and done, while still doing well with the fuel that Germans had the most - the 87 octane.

My argument is that focusing on H, X, W or whatever exotic layouts you can come up with is a distraction from solving the problems that are making their V-12's noncompetitive. Solve those, and the 603 and 213 are more than good enough until jets take over. And without solving those issues, the hypothetical H-16 won't be particularly good either.

 

[don4331]

The issue I see with an H-16 - there isn't enough difference between the 'sorted out' H-16 and 'current' V-12 to justify the extra weight/frontal area:

Date	V-12	H16
1937	Jumo 211A, 1,000 hp	prototype
1940	Jumo 211D, 1,200 hp	H16A 1,335 hp
1941	Jumo 211F, 1,350 hp	H16D 1,600 hp
1943	Jumo 211F, 1,500 hp	H16F 1,800 hp
1944	Jumo 213A, 1,750 hp	H16P 2,000 hp

I agree you have to go to more cylinders as the DB603 has same issue - the bigger cylinders/longer stroke means it never makes sufficient additional power to justify its increased weight.

And that's effectively the issue with the Vulture, by the time it makes 1,750 hp reliably, so is the Griffon. At least the Sabre makes 2,200hp (we can debate how reliably), so between not wanting to get locked into sole source supplier and Typhoon/Tempest being designed for Napier's engine, it soldiers on.