The Secret Horsepower Race by Calum Douglas (and piston engine discussion)

You need to keep in mind, that this engine was built out of cheap materials (whatever was available in the moment) and often assemblied by forced labour, so it is not to suprising, if it doesn't have a lot of reserves.
That's the usual excuse, in my opinion. For example, in 1944 the Cyclones in the F2A had about 11 times higher time between failures. And by 1944 the original supply of spares etc. had been dried up for several years and some Cyclones could have parts from Soviet M-62 engines fitted instead of originals. So even with quite up to date factory support the DB had very short service lives, even shorter than those of the Soviet engines, for which Finns had no steady supply of parts or even repair manuals. And the Bristol Mercuries in Blenheims had also several times higher TBF. And again, factory support had ceased by 1941.

If you read the damage description, it is very obvious that the "damage mechanism" has nothing to do with materials used
 
As long as this failure mode wasn't decisive in combat, it isn’t really of a major importance. Those engines were war machines which were designed and tested for a single purpose.

I remember, KTM developed high performance cross bikes which were intensively tested by professional race drivers without any flaw, but they tended to crack at the fork when used by amateurs, because they tended to land with the front wheel first, whereas professional cross drives always land on the rear wheels. Its like the clutch of your driving school car…

Keep in mid, new German pilots had hardly any training at all before beeind send to the front in the later war!
 
Last edited:
It was a very decisive fault because it killed the availability rate for combat. Either send pilots to combat without any combat training with the fighter or kill the engine life. A miserable engine.
 
Well, that's happend anyway, there wasn't even enough fuel for pilot training, so the first time the pilots entered a cockpit of a Me109 was usually the first time they were send into combat!
 
I don't have a dog in this, but a simplistic statement like DB-605 is a POS engine is not really accurate imo. The germans did not have the quality fuel, materials and lubricants their opponents did (major reasons for the unreliability issues), but despite all that they still got 2000 PS out of it, true with a life of 30-40 hours, but most planes didn't survive that long in wartime anyway. There is more to this of course but that's the basic idea.

The swedes got 1700 PS of of their licence built DB-605As with iirc 100/130 octane fuel and presumably better materials, so that gives an idea of the potential. Did they had reliability issues? Would be curious to know.
 
I don't know whether this has been discussed yet, but what advantage was the Rolls-Royce Goshawk supposed to really have over the Kestrel of identical displacement? I can't figure out what advantage evaporative cooling was supposed to provide, considering the obvious increase in complexity. Surely the MoD should have realized that a larger engine would be needed soon, and kudos to R-R for figuring that out and developing the Merlin as a private venture.
These were the days before glycol coolant, and water is heavy stuff. By letting the water boil, and having most of the cooling system filled with steam, much less water is needed, and hence a lot of weight is saved. The downsides are, of course, that in manouvreing flight, the steam and water tend to swap places, causing vapour locks in the system, and the condensers required in the place of radiators take up a lot space, tend to distort when they expand causing leaks at the joints, and even distort the aircraft's flying surfaces sufficiently to jam the controls . . .

cheers,
Robin.
 
That's the usual excuse, in my opinion. For example, in 1944 the Cyclones in the F2A had about 11 times higher time between failures. And by 1944 the original supply of spares etc. had been dried up for several years and some Cyclones could have parts from Soviet M-62 engines fitted instead of originals. So even with quite up to date factory support the DB had very short service lives, even shorter than those of the Soviet engines, for which Finns had no steady supply of parts or even repair manuals. And the Bristol Mercuries in Blenheims had also several times higher TBF. And again, factory support had ceased by 1941.

If you read the damage description, it is very obvious that the "damage mechanism" has nothing to do with materials used
Well, if you`re read my book you`ll know that bad materials WERE an extremely good excuse and were directly responsible for the entire Luftwaffe having emergency boost disabled for the two most critical years of the war.
(by which I mean the last two where any sort of chance existed to win).

Its absolutely true also, that the DB engine has several design flaws in the oil system which the Jumo 213 didnt have, but I do not think those errors can make an engine fail on their own, in 20 hours. I think its pretty obvious that the inherent design faults of not having a centrifuge, or a nose oil feel amplify quality issues in oils and bearings, but these same designs were used on DB 601`s pre war when the engine life was pretty similar to any comparable Allied types.

I dont think the Germans had any chance of making ANY engine work on the same level as Allied types (i.e. hundreds of hours between overhauls. We know that the BMW 801 was regarded very poorly too, and in Milch`s papers he writes it was nicknamed the "pig" by ground crews at the front in 1941/42. The DB 605 was called the "flower pot", I do not know why, but I do know it was certainly intended as an insult, one clear possibility is that flower pots break very easily.

As you all know I regard the Jumo 213 as clearly the best German V12, but (for example) we know that the Jumo`s suffered from all the same burned EXH valve heads as did DB and BMW. So, yes arguably the 605 was perhaps not as good as the 213 (which it should not have been, the 213 was a much later design), but in proper circumstances I think it would have been a perfectly servicable engine, especially in late model form with the "Ölschleuder". Germany never got near those proper circumstances though...
 
I seem to remember that the average life of 109 airframe was less than 20 hours due to battle damages, accident or lack of experience. So the problem was not as acute as it seems.
 
I seem to remember that the average life of 109 airframe was less than 20 hours due to battle damages, accident or lack of experience. So the problem was not as acute as it seems.
That appears true until you look at victory statistics, most USAAF pilots never hit anything. Your achievements in the air will be down to a core group of effective pilots, I don't have the figures to hand but from memory, something like 75% of victories were made by pilots who had scored 2 or more kills, which was a fairly small percentage of the total number of airmen who passed through the USAAF. So if you cannot provide reliable aircraft, it might not appear to matter from the average life of a combat airframe, but it will have a dramatic impact on your overall fighting effectiveness because it will put a massive strain on your ability to keep your best pilots alive, who, obviously are going to be flying for a long time, years in the case of the Germans.

DB 605 failure killed Joachim Marseille and large numbers of decorated German pilots.

18th May 1943: RLM Stenographic Records

“Milch: Now we come to the engine, I am very
concerned about the DB 605 and have come
back from the front and can say that after
discussing it there, that the opinion on this
engine is very poor. They handed me a list
of names, which went ... ‘on this date such
and such died because you have sent them to
their deaths’ and so on ... this is not seen as
being a safe engine, it is the sorry case of the
bearings which brings about the question of
the connecting rod failures. I have figures from
the night fighter units showing that no fewer
than two bearers of the Knight’s Cross have
been liquidated through this, and even Streib*
had to bail out and only escaped the cockpit at
low altitude after a fall of several thousand
metres.

I am unbelievably worried, this has been
going on for a long time, it was the same in
Africa with Marseille. There is a great crisis of
confidence with this engine."

* Werner Streib, decorated German night fighter ace. Sixty six victories, almost all large bombers.
 
Last edited:
That appears true until you look at victory statistics, most USAAF pilots never hit anything.

That's a very strange statement about an Air Corp that undoubtedly won the war.
Pilots can hit many things, including aircraft that are further down the line claimed by others, for various reasons, ground infra, vehicles, men, horses...
There is not much of a pilot that hits nothing in a war waged by a dominant air force with superior training and material.

The Stat for 109 airframe average hour life were also put down by Historian before.
 
Last edited:
That's a very strange statement about an Air Corp that undoubtedly won the war.
Pilots can hit many things, including aircraft that are further down the line claimed by others, for various reasons, ground infra, vehicles, men, horses...
There is not much of a pilot that hits nothing in a war waged by a dominant air force with superior training and material.

The Stat for 109 airframe average hour life were also put down by Historian before.
By "hit" I mean down an enemy plane, and most didnt. This is a general comment about air warfare, not some odd anti American joke.
 
I seem to remember that the average life of 109 airframe was less than 20 hours due to battle damages, accident or lack of experience. So the problem was not as acute as it seems.
From the Finnish view, that is not true. Finnish average flying hours per airframe was several hundred hours in total and the airframe TBO was 240 hours according to the post-war manual.

It should be also noted that the Bramo radials of the Do 17 were much more reliable in Finnish service.
 
That's a very strange statement about an Air Corp that undoubtedly won the war.
Pilots can hit many things, including aircraft that are further down the line claimed by others, for various reasons, ground infra, vehicles, men, horses...
There is not much of a pilot that hits nothing in a war waged by a dominant air force with superior training and material.

The Stat for 109 airframe average hour life were also put down by Historian before.

A very strange statement. "won the war" is repeated with little thought to the overall situation. If the bombers survived the anti-aircraft defenses, they were then set upon by fighters. I've read more than a few accounts of Allied bombers that were not shot down near the target but which were so badly damaged that they either crashed in England or somewhere in the North Sea. A few made it to Switzerland and crashed there, depending on the location of the original target. Then there is the issue of fuel injection. German fighters had it while British fighters did not. If a pilot had to roll his aircraft during combat, the engine could cut out due to lack of fuel, while the enemy could perform the same maneuver with no ill effect.

The Allies had to put hundreds of bombers into the air at a time. Early on, the RAF missed more often than they hit. Losses from daylight attacks were such that missions were flown at night. The end result was a smothering of the German efforts by weight of numbers.
 
Hi Calum,

That appears true until you look at victory statistics, most USAAF pilots never hit anything. Your achievements in the air will be down to a core group of effective pilots, I don't have the figures to hand but from memory, something like 75% of victories were made by pilots who had scored 2 or more kills, which was a fairly small percentage of the total number of airmen who passed through the USAAF.

Mike Spick's "The Ace Factor" quantifies this for 2156 pilots with air-to-air kills:

Number of Kills - Percentage of Pilots:
0.5 - 1: 47.8%
1.5 - 2: 23.0%
2.5 - 3: 10.5%
3.5 - 4: 5.0%
4.5 - 5: 4.5%
5.5 - 7: 4.1%
7.5 - 10: 2.5%
10.5 - 20: 2.3%
20.5 - 31: 3%

Caption:

"This survey spilts the number of USAF 8th Air Force pilots who could claim at least a share in an air-to-air kill, into sections by score. Fairly representative of all such analyses, it also bears out the recurring figure that five per cent of all pilots account for forty per cent of all victories. The constant theme is that very few pilots are any good at air combat. In all, some 5,000 pilots of the 8th Air Force flew against the Germans between 1943 and 1945, although it must be admitted that for some there was no opportunity."

For some reason, when I put the book on the shelf some ten years ago, I left a bookmark exactly on the page with the above statistic :)

Regards,

Henning (HoHun)
 
Excellent reading. I like when the books are combining technology with people histories. Calum only one thing you need to change - please increase font size, the one used now is difficult to read even in good lighting condition.
 
If I have difficulty reading a book because my eyes aren't what they used to be, I read it on a table with extra strength lighting overhead. That usually helps.
 
Hi Hanz2k,

Excellent reading. I like when the books are combining technology with people histories. Calum only one thing you need to change - please increase font size, the one used now is difficult to read even in good lighting condition.

With Calum being an engineer, best way to communicate the problem is probably a curve ;-)


Regards,

Henning (HoHun)
 
On the issue of average engine life, spread is a bigger headache than a low average. The 25 hour life of the Jumo 004 turbojet included plenty of units that died after fewer than 10 hours, mostly because clumsy throttle use during start up would over temp the turbine. If the squadrons could rely on 20 hours from their DB605s then swapping them out at that point would allow them to fight. If on the other hand an engine with 10 hours on it failed during a combat mission you might lose the plane and the pilot. It does nothing for morale or combat readiness.
 
Hi Oliver,

On the issue of average engine life, spread is a bigger headache than a low average. The 25 hour life of the Jumo 004 turbojet included plenty of units that died after fewer than 10 hours, mostly because clumsy throttle use during start up would over temp the turbine.

Do you happen to have data on this spread? I've been keeping my eyes open for this for a while, and never came across anything with good level of detail, so your find would be very welcome! :)

Regards,

Henning (HoHun)
 
On the issue of average engine life, spread is a bigger headache than a low average. The 25 hour life of the Jumo 004 turbojet included plenty of units that died after fewer than 10 hours, mostly because clumsy throttle use during start up would over temp the turbine. If the squadrons could rely on 20 hours from their DB605s then swapping them out at that point would allow them to fight. If on the other hand an engine with 10 hours on it failed during a combat mission you might lose the plane and the pilot. It does nothing for morale or combat readiness.

What is all that based on? I located an unpublished photo of an Me 262 being serviced in the field. Engine swap out took about 30 minutes and there were plenty of spares.
 
Its very difficult to get the balance correct for everyone regarding things like text size, the publisher had a limit on the size of book they thought was practical, and I already cut about 100 images out to get more space. A lot of people wanted the images to be bigger, in that case I have to cut text or make it even smaller.

The typewriter font was actually not the one I wanted to use, it was fainter. This was because the font I selected was apparently not recommended by the printer due to some printing incompatibility (I don't really understand, but anyway they said I had to find another one).

If we do a major 2nd edition, I think we will put it into two volumes, and I will use a different typewriter font. Possibly in that case it may be possible to increase the font size by 1 point.
 
Under no circumstances should the font size be increased. The main problem is that typewriter font is too light and "scratchy" (=like parts of the lettering is worn off). The main font is a bit light too. I would strongly recommend Adobe Jenson Pro font family. Works very well in small sizes and poor lighting.
 
Question: Jumo 211F/J was produced in (at least) 2 series, Baureihe 1 and Baureihe 2. The engine lists over a page of modifications in the series 2 including new crankshaft, revised exhaust valve timing and "new Ortlinghaus clutch" for the supercharger.

How was production split between these, how many Baureihe 1 were produced, how many Baureihe 2?
 
Its very difficult to get the balance correct for everyone regarding things like text size, the publisher had a limit on the size of book they thought was practical, and I already cut about 100 images out to get more space. A lot of people wanted the images to be bigger, in that case I have to cut text or make it even smaller.

The typewriter font was actually not the one I wanted to use, it was fainter. This was because the font I selected was apparently not recommended by the printer due to some printing incompatibility (I don't really understand, but anyway they said I had to find another one).

If we do a major 2nd edition, I think we will put it into two volumes, and I will use a different typewriter font. Possibly in that case it may be possible to increase the font size by 1 point.

From :-

6.2 Other best practice for print publications
Fonts

The clear print standard requires a minimum font size of 12 point. However, you may wish to use a larger font depending on your audience. Using a point size of 16 means that there is no need to have a separate stock of large print documents. You should also be able to supply large print in various sizes above 16 point, on request.

Density and complexity of font type can reduce space – look for a simple font that spaces letters out.

Avoid italics, underlining, simulated handwriting, unusual shaped letters and decorative typefaces.

Consider the length of letters b, d, f, h, k, l, t, g, j, p, q, y in relation to the x height of the typeface. Short ascenders and descenders make a typeface less legible.

Fonts with uneven stroke widths tend to be less legible than fonts with even strokes.

Consider individual characteristics of letter shapes. For example a closed ‘a’ is more likely to be confused with a ‘c’ or an ‘o’ than an open ‘a’, and a ‘3’ can be confused with an ‘8’ in some fonts.

Research your audience’s preferences – consider user-testing your font with a range of impairment and age groups.
Type weight

Lighter type weights can affect legibility, as readability requires good contrast. Bold or semi-bold weights are recommended for material specifically for people with visual impairments – but check the font is still easy to read.

Avoid using blocks of capital letters in titles or body text.
Design and layout

The best design is simple and uncluttered.

Set text horizontally, not on a slant.

Align text left for maximum legibility. Avoid right aligning or justifying text.

Keep line lengths to between 60 and 70 characters, roughly 12 to 18 words, per line.

Avoid using hyphens to split words between lines.

Allow plenty of space on forms. If details that have to be hand-written, make the boxes, including tick boxes, as large as possible.

Make sure that sections and chapters are clearly defined with headings.

Keep headings and page numbers in the same place on each page.

Keep paragraphs short and use line spacing between paragraphs. Use wide margins and headings. Boxes can help emphasise or highlight important text.

Include a contents page and consider including an index.

Tints can be helpful to break up a document and make it easier on the eye, particularly for statistical material, graphs and charts. Make sure there is a strong contrast between text and tint.

When setting text in columns, make sure the space between the columns clearly separates them.

Numbers

Make sure numbers are distinct when printed. The numbers 3, 5 and 8 can be misread, as can 0 and 6 in some fonts. For financial information use a large point size.

Also see :- https://www.sensorytrust.org.uk/resources/guidance/designing-with-clear-and-large-print

"Clear print

Clear print requires a minimum font size of 12pt Arial
The font that you use should be clear in its design, without too many flourishes. Avoid ‘handwriting’ or ‘fancy’ fonts
Space between the lines (leading) should be at least single spacing, preferably more
Text should be left aligned. Text that is centred or aligned on the right could be missed
Do not hyphenate words at the end of lines
Avoid using text on top of images; it is difficult to read and can be completely missed
Avoid using words that are all in capital letters, this can be hard for people with visual impairments or dyslexia to read

Producing clear print

When designing a document, leaflet or brochure it is important to remember that not all fonts have letters that are the same size. For example, 12 point text in Arial will appear larger than 12 point text in Calibri. If you are using a font other than Arial compare a paragraph or text in both the fonts and adjust your font size accordingly."

cheers,
Robin.
 
The company I work for uses 10 point text with variable size headlines. All caps is discouraged. Two column format is standard. The spaces between lines of text is referred to as leading.
 

In the link given, the recommendation of "minimum font size of 12pt Arial" for 'clear print' caught my attention. Then, I saw this: "Clear print guidelines should be adopted as a standard for all printed materials". Really?

That is the exact opposite of what I was taught in Typography classes (back in the Late Pleistocene). At the time, sans-serif 'display' fonts (like Arial or Typewriter) were considered acceptable for limited text in children's books but, otherwise, were restricted to titles and captions.

Back in the day, typical fonts for typesetting books were Baskerville, Garamond, Palatino, etc. The term 'book' referred to font weight (with 'book' fonts also having greater X-heights than their equivalent 'regular' fonts). Readability was thought to be enhanced by serifs (along with the use of standard leading, a balanced amount of 'white space', etc.). Has all of this now been reversed?

I do note that much of the traditional typographical terminology has been replaced by 'Microsoftese'. In place of an added hair of leading we have '1.15 spacing'. I get that computer-driven typography complete dominate now and terminology should be updated to stay relevant. However, my sense is, those programmers who dictated the changes were well-versed in IBM Selectric usage not in typography.

Have rules of thumb such as 11/11 for popular books with 10/10 for academic works, have now been completely discarded? In their place, someting akin to 12/13 now seems to be regarded as a paltry - possibly even inadequate - font size and leading for publishing. I have difficulty seeing these new 'standards' as representing progress ...
 
In the link given, the recommendation of "minimum font size of 12pt Arial" for 'clear print' caught my attention. Then, I saw this: "Clear print guidelines should be adopted as a standard for all printed materials". Really?

That is the exact opposite of what I was taught in Typography classes (back in the Late Pleistocene). At the time, sans-serif 'display' fonts (like Arial or Typewriter) were considered acceptable for limited text in children's books but, otherwise, were restricted to titles and captions.

Back in the day, typical fonts for typesetting books were Baskerville, Garamond, Palatino, etc. The term 'book' referred to font weight (with 'book' fonts also having greater X-heights than their equivalent 'regular' fonts). Readability was thought to be enhanced by serifs (along with the use of standard leading, a balanced amount of 'white space', etc.). Has all of this now been reversed?

I do note that much of the traditional typographical terminology has been replaced by 'Microsoftese'. In place of an added hair of leading we have '1.15 spacing'. I get that computer-driven typography complete dominate now and terminology should be updated to stay relevant. However, my sense is, those programmers who dictated the changes were well-versed in IBM Selectric usage not in typography.

Have rules of thumb such as 11/11 for popular books with 10/10 for academic works, have now been completely discarded? In their place, someting akin to 12/13 now seems to be regarded as a paltry - possibly even inadequate - font size and leading for publishing. I have difficulty seeing these new 'standards' as representing progress ...
Sans for titles/short text and serif for paragraphs is the guideline for web design.

I think the linked site is specifically about pamphlets and the like, there is a section that says "Whereas clear print is appropriate as a standard for all printed information large print is an alternative format and is beneficial for people with visual impairments.". The bit about all printed materials is poorly worded.
 
In the link given, the recommendation of "minimum font size of 12pt Arial" for 'clear print' caught my attention. Then, I saw this: "Clear print guidelines should be adopted as a standard for all printed materials". Really?

That is the exact opposite of what I was taught in Typography classes (back in the Late Pleistocene). At the time, sans-serif 'display' fonts (like Arial or Typewriter) were considered acceptable for limited text in children's books but, otherwise, were restricted to titles and captions.

Back in the day, typical fonts for typesetting books were Baskerville, Garamond, Palatino, etc. The term 'book' referred to font weight (with 'book' fonts also having greater X-heights than their equivalent 'regular' fonts). Readability was thought to be enhanced by serifs (along with the use of standard leading, a balanced amount of 'white space', etc.). Has all of this now been reversed?

I do note that much of the traditional typographical terminology has been replaced by 'Microsoftese'. In place of an added hair of leading we have '1.15 spacing'. I get that computer-driven typography complete dominate now and terminology should be updated to stay relevant. However, my sense is, those programmers who dictated the changes were well-versed in IBM Selectric usage not in typography.

Have rules of thumb such as 11/11 for popular books with 10/10 for academic works, have now been completely discarded? In their place, someting akin to 12/13 now seems to be regarded as a paltry - possibly even inadequate - font size and leading for publishing. I have difficulty seeing these new 'standards' as representing progress ...

Having done paste-ups by hand, and being thoroughly familiar with the proper use of white space, so-called "modern" standards translate as: "Make sure it doesn't look like the old stuff." Not progress at all, just a redefining based on apparently arbitrary decisions. In other words, what is readable today was readable 50 and 100 years ago.
 
Several of the ideas linked by Robunos are horrible, like ragged-right, avoiding hyphenation or a minimum of 12 pt. A person recommending those for serious books should be sent to a North Korean labour camp. Ragged-right + no hypnenation easily increases page count by at least 5 %.

Journals like Aircraft Production, Aircraft Engineering and De Havilland Gazette were extremely well laid out in the 1940s. Today an excellent layout can be found in Cross & Cockade journal. Also the later After the Battle was superb. Unfortunately, the Iron Cross is very poorly designed. Attached a sample from Mobilisti. Main font Adobe Jenson Pro 11 pt.
 

Attachments

  • 20211223_132332.jpg
    20211223_132332.jpg
    2.6 MB · Views: 22
Several of the ideas linked by Robunos are horrible, like ragged-right, avoiding hyphenation or a minimum of 12 pt. A person recommending those for serious books should be sent to a North Korean labour camp. Ragged-right + no hypnenation easily increases page count by at least 5 %.

Journals like Aircraft Production, Aircraft Engineering and De Havilland Gazette were extremely well laid out in the 1940s. Today an excellent layout can be found in Cross & Cockade journal. Also the later After the Battle was superb. Unfortunately, the Iron Cross is very poorly designed. Attached a sample from Mobilisti. Main font Adobe Jenson Pro 11 pt.
Sorry, your phrasing made it a little unclear to me if your "sample" is supposed to be representing good or bad design ? Can you clarify which it is in your view?
 
I have a little time now to address some of the points raised.
The 'Clear Print' guidelines are primarily aimed at Public Sector information publications, such as, as sienar says, leaflets and pamphlets ( and the instructions for screening, and COVID, test kits for example), as well as utility bills, etc., and therefore not entirely appropriate for books and magazines. 12pt text, for example, is too big for a book, this would lead to an excessive page count (= cost).
The main point I was trying to make was this :-
'The font that you use should be clear in its design, without too many flourishes. Avoid ‘handwriting’ or ‘fancy’ fonts'
@Apophenia, @sienar; I'm afraid typography is as much a victim of fashion as anything else nowadays, so yes, 'make it look different to the old stuff' is indeed what happens, especially if you're selling a new edition of a book that has no additions or revisions to the previous edition . . .
@Paseolati, the 'Clear Print' guidelines only advise Left Aligned text, this does not automatically mean ragged right, fully justified is acceptable, indeed preferable. No more than two columns, though, as more leads to excessive word splitting, with or without hyphenation. Sorry, but your sample is foul, to use the word we would call that when i worked in the print trade, 'Tombstones' . . .
An example of good design that I would give would be Chris Gibson's Crecy titles.
Again,@Apophenia, your typography studies may have been in the late Pliestocene, but what you learned (apart from the basics) has definitely gone the way of the mastodon . . .

cheers,
Robin.
 
Back
Top Bottom