New book on WW1 aircraft design and performance

[No.23_Starling]

Salute friends and pilots!

 

It looks like Mr Holtze's book is now out - I've ordered my copy: WW1 Aircraft Performance, Anders F Jonsson, ISBN 9789198774801.

If you've not already had a read, a detailed description of the book, his engineering/aerospace career, and its contents can be found on his website: https://militaryaircraftperformance.com/

 

In addition to performance numbers, the book also covers a brief state-of-the-art description covering design, aerodynamics, structures, engine and armament development. From what I've seen the book is mainly focused on flight performance such as climb, ceiling, speed, dive and turn performance, and therefore allows comparisons to be made to many of the aircraft currently modeled in Flying Circus Volumes 1 & 2. The only other publication I know of where an engineer attempts to calculate turn performance of these planes is Gunning for the Red Baron, Leon Bennett, ISBN 158544507 where the models are not very sophisticated - this new book looks like a leap forward in the literature for WW1 aircraft performance modelling.

 

Since models are just models, they are not perfect and can be tweaked; that goes for both the in-game flight modeling (you'd think) and the simulations in the book. It begs the question on whether we could use this new dataset to adjust FC's FMs or create new engine variants for the same planes (or even totally new planes!); it would also be great if people could post additional sources of data in this thread to compare with Mr Holtze's book. I have my own library of RAE and Hispano Suiza tests ready to thumb.

 

Holtz - I hope you dont mind me stealing your thunder here! Many of us are very excited to read what you've put together.

 

Rummy

 

EDIT: just updated the URL to the book - same edition, just a new link

Edited February 17, 2023 by US103_Rummell

[Holtzauge]

32 minutes ago, US103_Rummell said:

Holtz - I hope you dont mind me stealing your thunder here! Many of us are very excited to read what you've put together.

 

Not at all!  And thanks for the vote of confidence! I just hope you won't be disappointed!

 

In addition, I took the liberty of sending a PM to @Han offering 1CGS a copy of my book so we'll see how that goes.

 

Edited February 11, 2023 by Holtzauge

[ZachariasX]

Ha... I just had pulled (after some negotiations) the trigger on a copy of Dechamps, H. und K. Kutzbach: Prüfung, Wertung und Weiterentwicklung von Flugmotoren. Still unsure if the (for us) relevant aricles in that volume are present readable. Fingers crossed. For $70 including shippment, I don't know what to expect. Most exapmles I found were obscenly pricy. Hate buying antiques without putting my fingers on it first, but what can you do? As I'll be on vacation the coming two weeks, shippment has to wait. And pulling the trigger on that one will have to wait accordingly.

 

But by all means congrats @Holtzauge for getting it done!

[J99_Sizzlorr]

Yeah congratulations on your book release. I hope it peforms to your expectations.

[=IRFC=Tunes]

Ordered!

[Holtzauge]

7 minutes ago, =IRFC=Artun said:

Ordered!

 

Now all we need is some trials data to compare too! 

[JGr2/J5_Wolff]

My copy is on the way.

[No.23_Gaylion]

I suggest getting in contact with "The Great War Group" so it hits a wider WWI audience. 

[Holtzauge]

9 minutes ago, No.23_Gaylion said:

I suggest getting in contact with "The Great War Group" so it hits a wider WWI audience. 

 

Have not heard about them so thanks for the tip! Will certainly check it out!

[No.23_Gaylion]

They showcase books like yours, self published etc.

[US103_Baer]

20 hours ago, =IRFC=Artun said:

Ordered!

+1

[Holtzauge]

On 2/11/2023 at 3:12 PM, Holtzauge said:

In addition, I took the liberty of sending a PM to @Han offering 1CGS a copy of my book so we'll see how that goes.

 

Quick update: @Han replied to my PM and added some additional developers to the PM thread. I'm happy to say that they are interested in the book, so I will send them one as soon as I get my personal copies which is slated for the end of the month.

 

However, I have no idea about the time it will take for the book to reach its end destination, but I can't imagine it will be before the middle of next month.

 

Anyway, I'm happy to send them one and hope they will find it useful! 

[=IRFC=Tunes]

Amazing news!

[No.23_Starling]

Fantastic! Mine should be here next week. My family will not see me for a few evenings.

[No.23_Starling]

The book arrives! Needless to say I was not disappointed and devoured it in 2 days. I've never before come across such a comprehensive study of WW1 aeronautical engineering written by someone with this level of technical knowledge, as well as a keen eye for history (and familiar with both German and British/French sources), and strong contacts within the European vintage aviation community.

 

Most books on WW1 aviation tend to be histories and/or coverage of surviving data sources, but very few if any dig into the detail of what we can learn applying modern modelling techniques to the evidence we have available, probably because most are written by historians and not engineers.

 

I wont spoil it but will say that @Holtzauge covers a brief history of aeronautical engineering in the early C20th, every engineering aspect of consequence that might materially impact aircraft performance from types of drag, to wires, engines, wing shapes, aspect ratio, fuels etc etc, as well as what surviving data he's used to tune his models which take into account tons of variables. You will likely need some knowledge of engineering and half decent math skills to fully understand the content - it's deep!

 

You've then got the good stuff on performance data which throws up a couple of surprises to anyone who has flown Rise of Flight and then Flying Circus for many years, but perhaps not that shocking in some cases (Mr Jonsson has already shared some data with us on the poor N28).

 

If I were a sim developer this would be my handbook, and I'd be knocking his door down to get access to his models, plus ask for more types to be plugged in. It begs the question of what 1C could do to the flight models with such data.

 

I'd be interested to hear more thoughts on this thread from other people who have ordered a copy.

 

Bravo @Holtzauge

 

EDIT: it's also interesting to see how much the developers have actually got right (if the models are accurate) without access to former SAAB employees. I get the sense that the sim can only get better.

 

Edited February 22, 2023 by US103_Rummell

[Holtzauge]

1 hour ago, US103_Rummell said:

The book arrives! Needless to say I was not disappointed and devoured it in 2 days.

 

I’m glad you liked it!

 

1 hour ago, US103_Rummell said:

it's also interesting to see how much the developers have actually got right (if the models are accurate) without access to former SAAB employees. I get the sense that the sim can only get better.

 

This is a good point @US103_Rummell: I think Flying Circus (and Rise of Flight) are very good and enjoyable simulations and I enjoy flying the planes in both of them. And as you say, many things are done right and I would recommend anyone interested in WW1 aviation to get both titles.

 

That being said, there is always room for improvements in simulations. That goes both for the ones in Flying Circus and my C++ simulations. And when my personal batch of books arrive (scheduled for Tuesday next week) I will send a copy to the developer and take it from there.

 

I hope we could collaborate somehow and share ideas about what are the performance numbers to target. I am anyway open for such a collaboration and would gladly share my input if it could be of help to tune the flight models.

[ZachariasX]

It is indeed the book on WW1 aviation that I always wished I had. @Holtzauge did a monumental work putting all that together!

 

 

Speaking of books, this was just put in the mail today:

 

1. Bestellnr.: 323066 - Menge: 1
Artikel: Dechamps, H. und K. Kutzbach - Prüfung, Wertung und Weiterentwicklung von Flugmotoren - Berlin - Schmidt - 1921 - 307 Abb., 252 S., Werbeanhang - 27x19 cm - Leinen der Zeit ohne Titelprägung (könnten trotzdem der Org.-Einband sein)

 

Hopefully it arrives next week and it contains what I hope it contains…

 

[US103_Baer]

It's taken a while to find It's way around the world, but the wait is over. First flick through looks much more detailed than expected. Brilliant. Cannot wait to get into it. 

 

[Holtzauge]

4 hours ago, US103_Baer said:

It's taken a while to find It's way around the world, but the wait is over. First flick through looks much more detailed than expected. Brilliant. Cannot wait to get into it. 

 

 

Well I'm really glad to hear you liked it! In addition, I'm looking forward to discussing any questions you and others may have on it later on.

 

I intend to post some stuff here later on about my flight models and performance results, and how they compare to what we have in-game, but I have been holding back intentionally since I want the developers to get their copy of the book before I do.

 

I think this would be the most productive approach since otherwise, they will just get a lot of numbers with no context. Once they have the book though, it will be more clear why I arrive at the results I do. If you look in the book on pages 57-94 about wing profiles and wing planforms, these are really key to my models and why I get the results I do.

 

I sent the developers the book on the 28th February but the tracking info stopped at the Swedish border so I have no idea where it is now but I'm sure it will get there eventually! 

 

I have however in my PM conversation with the developers asked them to give me a heads-up when they get it and hopefully it will not be that much longer now.

 

The first thing I would like to ask them about is their take on the high altitude modeling, where my results are much more conservative. For example, my turn time estimates (See pages 187-188) are in some cases nearly double those we have in-game at 5 km altitude.

 

[US103_Baer]

@Holtzauge

Only 25% through it, but it's a book I can really settle down with and enjoy taking it all in. Feels like I'm reading history but seriously upgrading my aeronautical engineering knowledge at the same time. 

 

Can see it as a great level-up opportunity for the community too. Putting to rest many misunderstandings or incorrect assumptions.

 

Might suggest that when we get to the point of comparing your models to in-game testing, there is a very clearly stated test methodology that, naturally, aligns with the rules used in the computer model. 

When trying sustained and instant turn testing in FC using tacview I found quite small variations in speed or not watching altitude loss can make quite a difference to turn rates!

 

Loving the book. I can highly recommend it to anyone with an interest in WW1 aircraft performance.

 

Edited March 9, 2023 by US103_Baer

[Holtzauge]

About the testing procedure @US103_Baer: Many here have extensive experience flying the in-game aircraft and I have seen videos with some nice flying keeping both altitude and speed in turns. But yes, I agree that losing a bit altitude or allowing the speed to drop does affect the result so some skilled flying is needed to get the decimal points right. My method when I have been doing it myself is to literally fly in circles trying to keep speed and altitude correct and record a track. Then post analyze the track trying to figure out which portions are the best and taking the average time of those. But when it comes to the best method on how to do this in-game, I will gladly defer this to you guys who have a lot more in-game stick time and not as rusty as myself.

 

Testing the instantaneous turns in-game is a lot trickier: But I have seen some nice flying done by @=IRFC=Artun to test this on the Fokker Dr.I and I believe he is compiling in-game data on other aircraft as we speak. The book only gives the time to complete two turns (pages 192-194) but I have given Artun data on 360 degree turns as well for some of the in-game aircraft and can post more instantaneous turn data for 360 deg turns here later on.

 

As general observation, I think we will find that that the in-game aircraft retain speed better in instantaneous turns (some, maybe not all!) and get a better return on zooms from dives than my models predict. In addition, many of the Entente scouts do better in turns in my model at higher altitudes than in-game which I also believe is correct for the reasons I outline in the book.

 

[BMA_Hellbender]

I'm yet to finish the book cover to cover, though I've paged through most of it and so far it's been by far the most interesting reference work on WW1 aircraft performance I've ever had the pleasure to read. The title of the book does not lie. Without spoiling anything: I had an absolute aha moment when reading the chapter on requirement specifications and landing speed. The fact that sustained turn was never a product of any military or functional requirement makes a lot of sense.

 

That said, it exposes quite a few flaws in the current FMs -- except, maybe, unsurprisingly (and not yet 100% certainly) -- in the newly released Snipe and soon to be released Siemens-Schuckert. But since the Snipe is not part of the book and the Siemens-Schuckert isn't out yet, I can't definitively comment on it. But yes, let's restate the obvious: almost all the FMs are over 10 years old, while the Snipe and Siemens-Schuckert's FMs are brand new and developed in a new, modern engine, and so is the data coming from this book (from the C++ simulations). And to continue stating the bleeding obvious: we absolutely need engine variants on most if not all of the planes.

 

@Holtzauge: Please release a sequel with the Sopwith Pup, Dolphin, Snipe, Bristol Fighter, Albatros D.II, D.III, Nieuport 11, 17/23/24 and SPAD VII. Day 1 purchase.

Edited March 10, 2023 by =IRFC=Hellbender

[Holtzauge]

@=IRFC=Hellbender: I’ve said it to the others who have reviewed the book here and I will say it to you as well: I’m glad you like it! I spent an awful lot of time researching, collecting data, simulating and writing, so words of appreciation are of course more than welcome!

 

And about the turn performance never being part of the requirement specification: It was the same for Reginald Mitchell and the others competing for the new British fighter contract: It was a landing speed requirement that determined the wing size on the Spitfire nothing else. Interestingly though, there was for a short time a German requirement during the inter war years for “Wendigkeit” but that dropped quickly to third place behind climb and speed.

 

And when it comes to the point you make about engine variants I totally agree: If the Albatros FM is updated, the DVa is going to need the D.IIIaü engine to stay competitive because it's going to lose its turn advantage. OTOH I’m beginning to think that the turn estimate comparison I posted earlier saying that with that engine it would match the Nieuport 28 C.1 was a bit optimistic. The latest info I’ve gotten indicates it (the engine) was not quite that good but it does seem awfully hard to pin down exactly what it could do so that will need some more work.

 

But this is just the sort of thing I was hoping for a fruitful collaboration with the developers on: I have both data and my simulation engine. They probably have a lot of data on their end and one thing that we could both benefit from I think is to get a better understanding of what the Mercedes D.IIIaü was truly capable off since this would improve both our flight models.

 

About a WW1 sequel: I will probably put that on the back burner for now: I will most likely instead go for the low hanging fruit with the HUGE market potential: The Bf 109E versus the Spitfire Mk 1 during the BoB period: What could possible go wrong? Bound to sell like hotcakes! 

 

[J2_Trupobaw]

No joy. Perhaps it takes time to get it to Poland?

[Holtzauge]

2 hours ago, J2_Trupobaw said:

No joy. Perhaps it takes time to get it to Poland?

 

Sometimes takes long to Sweden too: When I ordered Michael Tate's Fokker Design and Development to 1919 from Lulu it took more than three weeks before I got it. OTOH I got the impression that for example @US103_Rummell & @=IRFC=Artun got their copies rather quickly after ordering?

[No.23_Starling]

1 hour ago, Holtzauge said:

 

Sometimes takes long to Sweden too: When I ordered Michael Tate's Fokker Design and Development to 1919 from Lulu it took more than three weeks before I got it. OTOH I got the impression that for example @US103_Rummell & @=IRFC=Artun got their copies rather quickly after ordering?

Yeah took about a week

[US103_Baer]

On 3/17/2023 at 1:25 AM, J2_Trupobaw said:

No joy. Perhaps it takes time to get it to Poland?

Mine took just under a month to get to SE Asia using the standard delivery. Tracking worked accurately though. 

 

Edited March 19, 2023 by US103_Baer

[Holtzauge]

Some ground rules about using or quoting data from the book:

 

I’m all for those of you who have the book quoting it or posting pictures of portions of the text.

 

However, what will be frowned upon and which I will ask to be removed are pictures of whole figures and diagrams.

 

So for example: “According to page 192, the instantaneous turn time for two complete circles for the Camel is 33 s, while for the Dr.1 it is 38 s according to page 194” is OK while posting the complete figures from those pages is NOK.

 

I hope you all understand why I would like to avoid seeing complete figures posted?

 

Because if not, then someone will post figure X on page Y, another page Z, and then the whole essence of the book will be out there in short order and I might as well remove it for sale.

 

 

[J2_Trupobaw]

On 3/19/2023 at 1:57 AM, US103_Baer said:

Mine took just under a month to get to SE Asia using the standard delivery. Tracking worked accurately though. 

 

If just arrived, sinking my teeth in!

[Holtzauge]

4 minutes ago, J2_Trupobaw said:

If just arrived, sinking my teeth in!

 

Good to hear Trupo! If you have any questions, just let me know!

 

Funny thing is, I just got a PM reply like 10 minutes ago from the 1CGS developer I sent the book to saying that he had got it as well!

 

[Holtzauge]

I'm happy to say that the book is now also officially endorsed by Achim Engels!

 

https://www.facebook.com/groups/2145618568814194

 

In addition, if you have not already visited it, the Museum für Flugzeugbau und technische Geschichte (MFtG) has a lot of interesting stuff on their pages and a lot of free download pdf's with detailed info and pictures about all the aircraft he has built. In addition, be sure to watch his MFtG Werkstattschau series on YouTube!

 

And of course Achim's son Finn Engels page as well: https://www.facebook.com/profile.php?id=100090940502518

 

Edited March 24, 2023 by Holtzauge

[J2_Trupobaw]

On 3/23/2023 at 4:32 PM, Holtzauge said:

 

Good to hear Trupo! If you have any questions, just let me know!

 

 

 

 

Questions, remarks, discussion points, not sure what to call them.

 

Can German fixation with climbing prop be extreme adaptation to their very limited modus operandi? Their fighter squadrons focussed on interception of riders over own territory, taking off when notified by phone of enemy formation crossing the lines and being guided from the ground by flak / flare shells. Could this "guided lead interception" approach - climbing to target altitude over their projected target, starting on the ground but with horisontal head start, with no need to disengage by raw horisontal speed either (they fought over friendly ground, so they could dive) be enough to explain preference of climbing props?

 

 

Edited March 29, 2023 by J2_Trupobaw

[Holtzauge]

2 hours ago, J2_Trupobaw said:

 

Questions, remarks, discussion points, not sure what to call them.

 

Can German fixation with climbing prop be extreme adaptation to their very limited modus operandi? Their fighter squadrons focussed on interception of riders over own territory, taking off when notified by phone of enemy formation crossing the lines and being guided from the ground by flak / flare shells. Could this "guided lead interception" approach - climbing to target altitude over their projected target, starting on the ground but with horisontal head start, with no need to disengage by raw horisontal speed either (they fought over friendly ground, so they could dive) be enough to explain preference of climbing props?

 

 

 

Yes, it looks like the Germans consistently prioritized climb over speed I think. This is not only indicated by their choice of propellers where they during WW1 almost always (compared to the Entente) go for bigger diameter propellers with smaller pitch for engines with roughly the same rpm and power output, e.g. the Le Rhone, Oberursel and Clerget rotaries.

 

But also from the so-called Adlershof competitions: At these they were very meticulous in registering the exact climb rates of every competing fighter, but when it came to speed only noted in which order the different entries stacked! So something like noting: “Well plane X is faster than plane Y, both of which are slower than plane Z” while no attempt seems to have been made to determine exactly how fast they were.

 

IIRC then this was also how the German requirement specifications looked for a time in the inter war years where they specify the order of merit as 1) Climb 2) Manoeuvrability 3) Speed performance. Or if it was speed before manoeuvrability, I don’t remember exactly but the point is that climb was definitely number 1. I think this changed a bit later though (definitely before WW2), when fast transports like the Heinkel 70 etc. appeared on the scene and it was realized that however well climbing and manoeuvrable the bi-plane fighters were, they would never catch the bombers.

 

[giftgruen]

Very interesting ! Ordered just now ? and already now happy to read it !

[Holtzauge]

4 hours ago, giftgruen said:

Very interesting ! Ordered just now ? and already now happy to read it !

 

Well I hope you will like it! ?And if you have any questions about the contents, then you can post them here or contact me directly via mail through the form on my homepage: https://militaryaircraftperformance.com/

 

Carl J. Bobrow, who is a Research Associate at the National Air and Space Museum/Smithsonian Institution, recently wrote a review on The Aerodrome forum that will also be published in the Classic Wings Magazine, The USAF Air & Space Power History journal, the Over The Front, and the Cross & Cockade journals. I'm thrilled about that since I have not yet reached out to any magazines or journals myself!

 

Edited April 4, 2023 by Holtzauge

[Holtzauge]

Just heard from Klassiker der Luftfahrt that they will be doing a review as well! 

[Holtzauge]

Breaking news!

 

My book is now also officially endorsed by Fokker:

 

This is me with Mr. Fokker holding my book. Smiles all around as you can see!

 

Jokes aside:  One day a few years back there was a new guy at the morning briefing who gave his named as Fokker. I was of course intrigued, and after having introduced myself, could not help asking him if Fokker was a common Dutch name? To which he replied that no, it was not. Naturally, this led to the follow up question if he was in any way related to the famous designer Anthony Fokker?

 

And to my surprise he said yes, and that the lines of ancestry converged somewhere around his great grandfather. Funnily enough no one on his end of the Fokker family was very interested in aviation at all, so as I understand it he is the sole surviving Fokker who flies planes today.

 

Yesterday, I knew he was going to be at the airfield, so I of course took the opportunity to tell him about the book I had written and present him with a copy which he is holding in the picture below.

 

I can only hope that he will like it. After all, a stamp of approval from Fokker himself would mean a lot to me…….

 

 

[giftgruen]

Saturday the ordered book was in my postbox.

Sunday morning I started and at night ( there was some interruptions ) I was through. Tired in office this morning ?

 

In general this is a really fascinating and interesting thing to read ( if interested in some theory for airplane aerodynamics in general ).

Even for someone who in generally knows how planes fly and work, this book will give some quite astonishing insights which ( though I cannot prove in reality ) sound reasonable and fact based.

 

( Well. My beloved DVa sadly is a rather bad design from aerodynamic point of view ?- couldnt we cheat a bit to make it shine brighter ? )

 

At least one thing we can all really see in Flying Circus after some flown missions:  Hit and run doesnt make so much sense with WW1s. Why ? read the book !

Some of the other topics and numbers I have the plan to compare book calculations vs FlyingCircus flightmodel.

 

Thanks, dear Holtzauge !

[Holtzauge]

My, you managed to get through it in a day Mr. Poisongreen? I’m impressed: Long time since I could process so much info in one day myself!

 

About the Albatros D.Va: Since you have read the book now, you know that that was a surprise to me as well: I was expecting more from it, but it really is a dog. Hard to believe when it’s such a good looking airplane, but there it is. What’s even worse, is that it looks like even the Mercedes D.IIIaü will not be the miracle cure it needs either. So sorry, just like the other Central heavyweights, it needs a BMW upgrade to get back in the race I’m afraid! 

 

But maybe you could consider converting to the Pfalz D.XII? I have modeled it in C++ now and it’s looking pretty good: Granted, I have no numbers for it in-game to compare to, but I think it like the Nieuport 28 is in need on a substantial boost in terms of turn performance. Now add that to a reasonable speed and outstanding climb and ceiling, and Central gains in the D.XII what it loses in the D.Va!

[giftgruen]

24 minutes ago, Holtzauge said:

My, you managed to get through it in a day Mr. Poisongreen? I’m impressed: Long time since I could process so much info in one day myself!

 

Hm.

yes, I am quite a fast reader.

no, I did not read it in the careful way one should read such books.  This is not possible within a day.

So I will read it a second time, more with focus on specific chapters. The first round was 'drinking beer'. Now the whiskey

 

Unfortunately, the sim tells not much about the real performance.

This is simply due to the fact that the AI is extremely stupid.

So it is no problem at all to fly circles around a Camel in my Albatros, cause the Camel pilot just doesnt 'really' pull.

And it's no problem to stay on a SPADs Six, cause the SPADs pilot doesn't use his speed.

 

So it's quite impossible to say something about weaks and strengths of a plane by flying this sim.

Each plane is good enough against this AI. A Rumpler Taube would probably do it as well.

 

BTW: Some numbers for the real 'early' planes could be very very interesting.

E.G. the Eindecker, a Morane Parasol, a Nieuport Bebe, or the british  Pushers (DH4, FE2b )

 

Could be interesting to see how much of aerodynamic progress can be seen in the first evolution steps of scouts.

Are the first evolution steps 'steeper' ?  ( maybe, then, I may hope that an Albatros DII shines again, compared to a DH4 or a Morane ? ... )

 

 

Edited April 24, 2023 by giftgruen