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Thread: Fokker Dr1 - wrong propellor?

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    Default Fokker Dr1 - wrong propellor?

    Page two of this article:

    http://www.airspacemag.com/history-o...no-ist=&page=2

    suggests that the Fokker Dr1 climbed well but was slow in forward flight because it may have been fitted with the 'wrong' propellor


    If the Dr.I could, in fact, outclimb the Sopwith Camel biplane that it often fought, it was not because it had an extra wing but, Bennett suggests, because its propellers were pitched to deliver maximum power at climbing rather than cruising speed. Fokker Triplanes did in fact lack in top speed what they possessed in climb.

    Interesting!

    Barry

  2. #2

    LOOP
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    That was an interesting article Some of it I knew allready but the thing with the prop I didn't.
    Nice find

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    Quote Originally Posted by LOOP View Post
    That was an interesting article Some of it I knew allready but the thing with the prop I didn't.
    Nice find

    Thank you!

  4. #4

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    Thanks, a very interesting article.

  5. #5

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    Hm, could be, could be. With a fixed-pitch propellor, you're going to get what you amke it for.

  6. #6

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    That was interesting but we have to remember that people had been flying for less than twenty years and they were still exploring aerodynamics. It amazing what they did achieve.

  7. #7

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    In general, Luftstreitkrafte aircraft used props optimised for climbing, British and French ones optimised for speed. Defensive aircraft had to be able to climb to altitude quickly, those on the offense were already there.

    This led to some problems for both RFC and Armee de l'air when facing night bomber raids.

  8. #8

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    Quote Originally Posted by 'Warspite' View Post
    Page two of this article:

    http://www.airspacemag.com/history-o...no-ist=&page=2

    suggests that the Fokker Dr1 climbed well but was slow in forward flight because it may have been fitted with the 'wrong' propellor


    If the Dr.I could, in fact, outclimb the Sopwith Camel biplane that it often fought, it was not because it had an extra wing but, Bennett suggests, because its propellers were pitched to deliver maximum power at climbing rather than cruising speed. Fokker Triplanes did in fact lack in top speed what they possessed in climb.

    Interesting!

    Barry
    Yes it is an interesting site and I've bookmarked it but I'm going to take some of what is suggested with a pinch of salt

    After von Richthofen’s death in 1918, another fighter, now considered the best of the war, quickly supplanted the Triplane: the Fokker D.VII. The D.VII had many assets, not least its Mercedes engine ...

    Really?

    [Added Clarification]
    Now I have argued in the past that the Mercedes DIII was not a bad engine at all but even I would be hard pressed to describe it as the DVII's greatest asset - or even one its better assets
    Fitting the DIIIa was a stop-gap measure due to the shortages of engines and although the DIIIau produced reasonable performance it was not as good as the BMW engine.
    Last edited by Nicola Zee; 04-19-2016 at 09:31. Reason: Added clarification

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    Quote Originally Posted by Nicola Zee View Post
    Mercedes
    Now I have argued in the past that the Mercedes DIII was not a bad engine at all but even I would be hard pressed to describe it as the DVII's greatest asset
    Fitting the DIIIa was a stop-gap measure due to the shortages of engines and although the DIIIau produced reasonable performance it was not as good as the BMW engine.
    In the context of that paragraph the author might only imply or mean mechanical reliability rather than overall performance. Also the introductory engine was the Merc and this was good but we all now know the the DVIIF with the BMW and crude super charger was going to be better.

  10. #10

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    Quote Originally Posted by Zoe Brain View Post
    In general, Luftstreitkrafte aircraft used props optimised for climbing, British and French ones optimised for speed. Defensive aircraft had to be able to climb to altitude quickly, those on the offense were already there.
    This led to some problems for both RFC and Armee de l'air when facing night bomber raids.
    Good gen, thanks Zoe.

    "He is wise who watches"

  11. #11

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    Quote Originally Posted by 'Warspite' View Post
    In the context of that paragraph the author might only imply or mean mechanical reliability rather than overall performance. Also the introductory engine was the Merc and this was good but we all now know the the DVIIF with the BMW and crude super charger was going to be better.
    Agreed it is possible to get the intent but the wording of the article is somewhat imprecise.

    Here's another example:

    The Sopwith Triplane was a pleasant-flying, stable, and even warm and cozy airplane—not a small concern when pilots prowled at 18,000 feet. A brief but intense international flurry of triplane designing followed. However, the only model to reach the front was the Fokker Dr.I.

    What the author, of course, meant was that the only Triplane after the Sopwith Triplane reached the font to reach the front was the Dr1.

    None of this nit-picking discredits the article but it does raise concerns.

    [Added]
    If the Dr.I could, in fact, outclimb the Sopwith Camel biplane that it often fought, it was not because it had an extra wing but, Bennett suggests, because its propellers were pitched to deliver maximum power at climbing rather than cruising speed. Fokker Triplanes did in fact lack in top speed what they possessed in climb.
    The quote implies the extra wings were irrelevant but this I think is misleading.

    There were three reasons why the Dr1 could climb like a monkey
    1. The propeller was pitched for climb
    2. The cantilever wing shape
    3. The extra wings - counting the wing on the undercarriage it had two extra wings...not one
    Now all three - including the extra wings - contributed.
    Last edited by Nicola Zee; 04-20-2016 at 01:40.

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    Quote Originally Posted by Nicola Zee View Post
    There were three reasons why the Dr1 could climb like a monkey
    1. The propeller was pitched for climb
    2. The cantilever wing shape
    3. The extra wings - counting the wing on the undercarriage it had two extra wings...not one
    Now all three - including the extra wings - contributed.
    I would add two other factors.
    4) While obsolescent by late 1917, it's rotary engine DID have a high power to weight ratio. The combination of the Dr1 airframe and the rotary engine brought out the best in both. The Dr1 with a Merc engine would have been a flop.
    5) Both the Dr1 and the DVII benefitted from thicker wings (the DVII even more so) which - counter-intuitively in 1917 - created greater lift. It was this factor and the general absence of bracing wires which allowed the DVII to prop-hang.
    Last edited by 'Warspite'; 04-20-2016 at 02:24. Reason: spelling error on to/two

  13. #13

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    Quote Originally Posted by 'Warspite' View Post
    I would add two other factors.
    4) While obsolescent by late 1917, it's rotary engine DID have a high power to weight ratio. The combination of the Dr1 airframe and the rotary engine brought out the best in both. The Dr1 with a Merc engine would have been a flop.
    5) Both the Dr1 and the DVII benefitted from thicker wings (the DVII even more so) which - counter-intuitively in 1917 - created greater lift. It was this factor and the general absence of bracing wires which allowed the DVII to prop-hang.
    Both good points - especially the power-to-weight ratio of the rotary Dr1 and, of course, the same applies to the power-to-weight ratio of the rotary Camel.

    And overall I found the article entertaining and informative but (considering the site is associated with the highly reputable academic institution of the Smithsonian) it is surprising the language used is so chatty and informal that some parts of it are very ambiguous.
    Last edited by Nicola Zee; 04-20-2016 at 04:26. Reason: Clarification

  14. #14

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    Interesting article. Thanks Barry!

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    Quote Originally Posted by Nicola Zee View Post
    Both good points - especially the power-to-weight ratio of the rotary Dr1 and, of course, the same applies to the power-to-weight ratio of the rotary Camel.

    And overall I found the article entertaining and informative but (considering the site is associated with the highly reputable academic institution of the Smithsonian) it is surprising the language used is so chatty and informal that some parts of it are very ambiguous.
    As a former proof reader I would totally agree with you about the loose style and ambiguity.

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    Quote Originally Posted by Franco Lucchini View Post
    Interesting article. Thanks Barry!
    Bless you. Amazing what you find when you trawl the dark corners of the net!

  17. #17

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    Quote Originally Posted by 'Warspite' View Post
    As a former proof reader I would totally agree with you about the loose style and ambiguity.
    The internet is the world's greatest and most wonderful reference library but few websites seem to employ a proof reader, fact checker or editor - which is one of the reasons I'm a bit of a luddite and still read books

  18. #18

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    Quote Originally Posted by 'Warspite' View Post
    As a former proof reader I would totally agree with you about the loose style and ambiguity.
    What do you expect from a dumbed-down world that #Can'tCommunicateBeyondTwitterHashtags ?
    Historical Consultant/Researcher, Wings and Sails lines - Unless stated otherwise, all comments are personal opinion only and NOT official Ares policy.
    Wings Checklists: WWI (down Navarre Nieuport, Ares Drachens) | WWII (complete)

  19. #19

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    Quote Originally Posted by Nicola Zee View Post
    There were three reasons why the Dr1 could climb like a monkey
    [...]
    3. The extra wings - counting the wing on the undercarriage it had two extra wings...not one
    Now all three - including the extra wings - contributed.
    Hmm -- I recall reading in a magazine a few years back that wind-tunnel tests had indicated the Dr.I's middle wing *wasn't* all that effective; being sandwiched between the other two wings disrupted airflow excessively....

  20. #20

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    Quote Originally Posted by csadn View Post
    Hmm -- I recall reading in a magazine a few years back that wind-tunnel tests had indicated the Dr.I's middle wing *wasn't* all that effective; being sandwiched between the other two wings disrupted airflow excessively....
    I remember the same thing: posted here somewhere. Not that the space between the wings is closer on the Dr.I than the Sopwith (right Chris). Also, most of the "failed" tripes by other companies had closer wings; often an existing design that had a third wing sandwiched in (notably, the Albatross Dr.I). However, given how ineffective Fokker's previous designs were, it had something going for it.
    Karl'
    It is impossible for a man to begin to learn what he thinks he knows. -- Epictetus

  21. #21

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    Quote Originally Posted by Diamondback View Post
    What do you expect from a dumbed-down world that #Can'tCommunicateBeyondTwitterHashtags ?
    Well, these people have been around always; it's just that it's so much easier to reach mass communication than before (and often harder to sift out the wheat from the chaff).
    Karl
    It is impossible for a man to begin to learn what he thinks he knows. -- Epictetus

  22. #22

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    Quote Originally Posted by Jager View Post
    I remember the same thing: posted here somewhere. Not that the space between the wings is closer on the Dr.I than the Sopwith (right Chris). Also, most of the "failed" tripes by other companies had closer wings; often an existing design that had a third wing sandwiched in (notably, the Albatross Dr.I). However, given how ineffective Fokker's previous designs were, it had something going for it.
    Karl'
    On the other hand, as an aerodynamically-shaped structural reinforcement comparative to what a Doppeldecker of similar design might have been, perhaps the third wing "earned its keep" in other ways than originally intended...
    Historical Consultant/Researcher, Wings and Sails lines - Unless stated otherwise, all comments are personal opinion only and NOT official Ares policy.
    Wings Checklists: WWI (down Navarre Nieuport, Ares Drachens) | WWII (complete)

  23. #23

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    Quote Originally Posted by Jager View Post
    Well, these people have been around always; it's just that it's so much easier to reach mass communication than before (and often harder to sift out the wheat from the chaff).
    Karl
    True... but the Idiots-to-Villages ratio has gotten way out of balance. I mean, I know we can't *all* be MENSA* candidates, but...
    *Full disclosure as someone eligible, most of the MENSA members I've met in meatspace aren't exactly the kinds I want to hang with anyway.
    Historical Consultant/Researcher, Wings and Sails lines - Unless stated otherwise, all comments are personal opinion only and NOT official Ares policy.
    Wings Checklists: WWI (down Navarre Nieuport, Ares Drachens) | WWII (complete)

  24. #24

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    Quote Originally Posted by Diamondback View Post
    True... but the Idiots-to-Villages ratio has gotten way out of balance. I mean, I know we can't *all* be MENSA* candidates, but...
    *Full disclosure as someone eligible, most of the MENSA members I've met in meatspace aren't exactly the kinds I want to hang with anyway.
    1) I would argue that they are only more visible and vocal now, and encouraged to be so.
    2) Intelligence does not lend one grace.
    Karl
    It is impossible for a man to begin to learn what he thinks he knows. -- Epictetus

  25. #25

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    Quote Originally Posted by Jager View Post
    1) I would argue that they are only more visible and vocal now, and encouraged to be so.
    2) Intelligence does not lend one grace.
    Karl
    Re 2):True, I'm living proof--and NEITHER lend character. Plenty of avaricious brainiacs out there, ditto silver-tongued oozers-and-schmoozers in the Cocktail Party Class... Those two options, I'd rather go hang with the less articulate, blunter-talking, straight-shooting guys and gals at the range.
    Historical Consultant/Researcher, Wings and Sails lines - Unless stated otherwise, all comments are personal opinion only and NOT official Ares policy.
    Wings Checklists: WWI (down Navarre Nieuport, Ares Drachens) | WWII (complete)

  26. #26

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    Quote Originally Posted by csadn View Post
    Hmm -- I recall reading in a magazine a few years back that wind-tunnel tests had indicated the Dr.I's middle wing *wasn't* all that effective; being sandwiched between the other two wings disrupted airflow excessively....
    The debate about how effective the Dr.1's extra wings were is valid. It is possible that the contribution to lift has been exaggerated. To be honest I don't know as my knowledge of aerodynamics is too limited. My objection to the wording of the [original] article is - due to ambiguous language - it seems to imply the extra wings made no contribution to lift at all. Almost as if wings are irrelevant to lift
    Last edited by Nicola Zee; 04-21-2016 at 00:16.

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    Quote Originally Posted by Nicola Zee View Post
    The internet is the world's greatest and most wonderful reference library but few websites seem to employ a proof reader, fact checker or editor - which is one of the reasons I'm a bit of a luddite and still read books
    Books… they are precious to me! (with apologies to Smeagol/Gollum)

    You will remove my books from my cold dead hand (with apologies to Charlton Heston)

    Yes, I also like books. I regularly 'rescue' and re-home good books from second-hand dealers, charity shops and car boot sales.
    There's a classic on the De Havilland Mosquito which regularly costs Ł25 to Ł30 on the second-hand circuit. (Mosquito by C. Martin Sharp and Michael Bowyer - 498 pages, Faber, 1967 and 1971). I found it at a car boot sale at former RAF North Weald for Ł1! Yes, I was a very happy boy!

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    Quote Originally Posted by Jager View Post
    1) I would argue that they are only more visible and vocal now, and encouraged to be so.
    Karl
    "Kill the monster… Kill the monster…"

    Click image for larger version. 

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    OK, having just 'dissed' the whole internet and everyone on it with my previous post, Wiki (yes, Wiki) says that the Siemens Schuckert also used a coarse pitch prop:

    https://en.wikipedia.org/wiki/Rotary_engine#World_War_I

    Used on several late war types, notably the Siemens-Schuckert D.IV fighter, the new engine’s low running speed, coupled with large, coarse pitched propellers that sometimes had four blades (as the SSW D.IV used), gave types powered by it outstanding rates of climb,

    The question of prop pitch on take-off was also an important matter in WW2. I seem to recall Douglas Bader was flying an early Hurricane with the two-pitch prop. On take-off he failed to select 'coarse', ran along the runway at high speed, unable to take-off, and eventually trashed the aeroplane. Coarse pitch was for take-off and sustained climb, fine pitch was for flying.

    Barry
    Last edited by 'Warspite'; 04-21-2016 at 16:28. Reason: spelling error

  30. #30

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    Quote Originally Posted by 'Warspite' View Post
    OK, having just 'dissed' the whole internet and everyone on it with my previous post, Wiki (yes, Wiki) says that the Siemens Schuckert also used a coarse pitch prop:

    https://en.wikipedia.org/wiki/Rotary_engine#World_War_I

    Used on several late war types, notably the Siemens-Schuckert D.IV fighter, the new engine’s low running speed, coupled with large, coarse pitched propellers that sometimes had four blades (as the SSW D.IV used), gave types powered by it outstanding rates of climb,

    The question of prop pitch on take-off was also an important matter in WW2. I seem to recall Douglas Bader was flying an early Hurricane with the two-pitch prop. On take-off he failed to select 'coarse', ran along the runaway at high speed, unable to take-off, and eventually trashed the aeroplane. Coarse pitch was for take-off and sustained climb, fine pitch was for flying.

    Barry
    Thanks for posting a good article and a fun anecdote about the Hurricane. A small bit of nit-picking (sorry). Just my personal preference but I would have kept the last part of the quote in

    Used on several late war types, notably the Siemens-Schuckert D.IV fighter, the new engine’s low running speed, coupled with large, coarse pitched propellers that sometimes had four blades (as the SSW D.IV used), gave types powered by it outstanding rates of climb, with some examples of the late production Sh.IIIa powerplant even said to be delivering as much as 240 hp

    The part about the hp enables the reader to infer that the power of the engine was also a factor...it wasn't just the prop

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    Quote Originally Posted by Nicola Zee View Post
    Thanks for posting a good article and a fun anecdote about the Hurricane. A small bit of nit-picking (sorry). Just my personal preference but I would have kept the last part of the quote in

    Used on several late war types, notably the Siemens-Schuckert D.IV fighter, the new engine’s low running speed, coupled with large, coarse pitched propellers that sometimes had four blades (as the SSW D.IV used), gave types powered by it outstanding rates of climb, with some examples of the late production Sh.IIIa powerplant even said to be delivering as much as 240 hp

    The part about the hp enables the reader to infer that the power of the engine was also a factor...it wasn't just the prop
    Fair comment!

  32. #32

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    Quote Originally Posted by Diamondback View Post
    On the other hand, as an aerodynamically-shaped structural reinforcement comparative to what a Doppeldecker of similar design might have been, perhaps the third wing "earned its keep" in other ways than originally intended...
    Possible -- also: Allowing all the wings to have a shorter overall span reduces the amount of energy needed to change their angles.

    As to Idiots: Around our house, the saying is "INT 18, WIS 3". _D&D_ players will get this....

  33. #33

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    The point with the S-S D.III/IV is particularly valid; it could climb like a scared cat, but was rather slower than most of it's opponents.
    Karl
    It is impossible for a man to begin to learn what he thinks he knows. -- Epictetus



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