|WikiProject Aviation / Aircraft||(Rated B-class)|
Caption of Infobox
The article on the Halberstadt D.II mentions the D.I, D.III, D.IV, and D.V. In fact it would be hard to imagine the article without those mentions of these other types. The subject of the article is currently the D.II, however - the only Halberstadt single seat fighter to be manufactured in series. If you want to change this then it is the main title at the head - not the upper caption to the picture, that needs changing. Perhaps move the article to "Halberstadt D types"?? I think not - but this would at least make sense. But the caption over the infobox - even in this case, would refer to the exact aircraft type illustrated. At least that is what happens everywhere else. Soundofmusicals (talk) 10:23, 17 April 2008 (UTC)
Alleged droop on Halberstadt's wing trailing edge
I have deleted this on the following grounds:
1. It is structural and aerodynamic nonsense! The Halberstadt "D" type wing was a conventional two spar structure. No source (other than Grosz) describes the wing structure in these terms - in fact several remark on the unusual wooden (NOT wire as common on German aircraft of this period) trailing edge. The two wing spars were evenly spaced, as is obvious from the positions of the (two bay) interplane bracing. The described droop is described as resulting from structural flexibility that would have produced marked loss of lateral (roll) control (not to mention a serious weakness and a tendency to catatrophic breakage of the wing) - whereas the real Halberstatdt "D" types had good controlability and were unusually strong.
2. The photographic evidence is based on a single photograph that does seem to show a curved (but not necessarily drooping) trailing edge on the lower wing. There is no sign of this feature on any one of the (many) other photographs available of this type - several of which are taken from angles that would clearly show the droop described by Grosz, were it actually there. The weight of photographic evidence is therefore quite clear. Perhaps the rear lower wing spar of the aircraft in the "droop" photograph is damaged - or maybe the effect in the photograph is caused by an experimental variation in wing shape? If it were in any way standard it would surely show up on more than one photograph of the type.
3. Grosz is a very well known air historian - and in theory an excellent authority. In some relatively recent works either written by, or attributed to him there are however statements, often backed up by photographs, that are either not found or flatly contradicted by other sources, and (as in this case) also by the weight of photgraphic evidence, not to mention common sense.
- Dear "SoundofMusicals":
- The PIPE Here...and I was quite surprised, myself, to see the DROOPY trailing edges on the Halberstadt D.II fighter's wing trailing edges some time ago. The entire lower wing trailing edge, as well as the upper wing's trailing edge, INBOARD of the ailerons, show this droop in QUITE a few photos (although NOT all of them) in the book that was my prime reference for information on the type, "Halberstadt Fighters-Classics of WW I Aviation", by Peter M Grosz, Albatros Publications, 1996, ISBN 0 948414 86 3.
- Among the total of 84 monochrome (black & white) photos of Halberstadt D-series fighter aircraft in that volume, a total of 59 photos of aircraft depicted in the aforementioned book, show a view which can allow the viewer to discern whether the aircraft in the image has the "droopy" trailing edges in question. Of these, a total of 44 of the photos show the distinct "droopiness" (perhaps better described as a "catenary-like sagging", for lack of a more accurate term) of the lower wing's trailing edge, with a few of these "droopy lower wing" TE photos also showing the upper wing's trailing edge similarly "sagging" inboard from the aileron's inner end, inwards to the pilot's forward vision cutout on the upper wing's center section.
- I've complied a GoogleDocs spreadsheet with the specific information on which "numbered" photos in the "Halberstadt Fighters-Classics of WW I Aviation" show the "droopiness" in question, with the filename of "Halby Droopy Wing Photos in Windsock Datafile.htm"...please let me know if you'd like to see it, and if you would, please let me know how I could Email it to you.
- Specifically, in answer to your three part initial reply, I'm answering thusly, hopefully with you reading my response, with a copy of the Peter M. Grosz-authored book that these photos appear in, so you CAN see for yourself what I've been writing about...with my answers in [brackets] for clarity's sake.
- "Alleged droop on Halberstadt's wing trailing edge...
- I have deleted your (good faith snd referenced) edit on this - on the following grounds:
- 1. It is structural and aerodynamic nonsense! [There ARE 44 out of 59 photos from the Datafile, that show exactly what I'm writing about!] The Halberstadt "D" type wing was a conventional two spar structure. No source (other than Grosz) describes the wing structure in the terms he uses - in fact several remark on the unusual wooden (NOT wire as common on German aircraft of this period) trailing edge. The two wing spars were evenly spaced, as is obvious from the positions of the (two bay) interplane bracing. [The drawings in the Datafile seem to show the forward spar at about 12% back-chordwise, from the leading edge, with the rear spar about 55% back chordwise from the LE.] The described droop is described as resulting from structural flexibility that would have produced marked loss of lateral (roll) control (not to mention a serious weakness and a tendency to catatrophic breakage of the wing) - whereas the real Halberstadt "D" types had good controllability and were unusually strong.
- 2. The photographic evidence is based on a single photograph [now you've got that 44 of 59 photos to check for this!] that does seem to show a curved (although not necessarily drooping) trailing edge on the lower wing. There is no sign of this feature on any one of the (many) other photographs [again, check the book!] available of this type - several of which are taken from angles that would clearly show the droop described by Grosz, were it actually there. The weight of photographic evidence is therefore quite clear. Perhaps the rear lower wing spar of the aircraft in the "droop" photograph is damaged - or maybe the effect in the photograph is caused by an experimental variation in wing shape? If it were in any way standard it would surely show up on more than one photograph of the type [and it DOES...about 70-75% of the time, from the photos in the Datafile!!!].
- 3. Grosz is a very well known air historian - and in theory an excellent authority [I'd NEVER doubt that for a minute!]. In some relatively recent works either written by, or attributed to him there are however statements, often backed up by photographs, that are either not found or flatly contradicted by other sources, and (as in this case) also by the weight of photgraphic evidence, not to mention common sense. I therefore tend to discount his "wilder" allegations, unless they are independently backed up from elsewhere.[Perhaps you could, for other aircraft...but the Halberstadt D-series Datafile's photos DO show that trailing edge droopiness "more often than not".]"
- I WILL easily admit, though, that those few times when the trailing edge does NOT show anything but a straight line, in a horizontal plane from root-to-tip, that it MIGHT have been possible to remove much of the "droopiness" by careful rigging adjustments to the wings' bracing wires. For example, removing the droop from the lower trailing edge COULD involve tightening three of the twelve cables bracing the wing on one side of the aircraft...specifically the rear inner bay's landing wire, the rear outer bay's flying wire, and the inner wing strut set's rigging cable that connected the lower wing's rear spar to the upper wing's forward spar. An adjustment scheme of that sort, to those three specific cables, could likely lift up the lower wing's rear spar "just enough", almost midway along its length, to remove much, if not "all", of the trailing edge's "droopiness" showing in the 70-75% of the photos I've mentioned previously.
- One theory I've read about on the Internet, concerning WHY the "droopiness" occurred, is something you might notice yourself when you view the photos...it seems like the "sag" in the trailing edge manages to bring the lower wing root's rear endpoint JUST ABOUT LEVEL with the lower edge of the fusleage sides, and this IS a conceivable...however improbable...reason it could have existed as we see it in those 1916 vintage photos in the Halberstadt Datafile special.
- A fellow RC Scale aeromodeler's forum "thread" on this exact subject (the DROOPY Halberstadt D-series wing trailing edge) can be found at http://www.rcuniverse.com/forum/m_2282370/anchors_2282370/mpage_1/key_/anchor/tm.htm#2282370 , and might be worth looking at as well...more people than "just myself" HAVE noticed that droopy lower wing TE (AND perhaps, also the droopy fixed portion of the upper wing's TE) on the Halberstadt D-series fighters, and were thinking of ways to replicate it ("yours truly" did post in that thread, as "posts no. 2, 9, & 26"). Also, in that particular forum thread, one "Henner Trabandt", as poster no.61 in the thread (more easily accessed at http://www.rcuniverse.com/forum/m_2282370/mpage_3/key_/tm.htm ), even brings up evidence from a German language book of why the droopiness might exist.
- Also, from what I've read on the linked RCU forum's postings, that there also could have been a conscious effort to place some washout in the Halby D.II's wingtip, which would have taken care of the higher angle "way out there", for stability's sake...and RC modelers, when building sport type (read "non scale") biplanes for slow aerobatic flying, and build a biplane with regular positive stagger to the wing arrangement, WILL consider making the lower wing have a lower angle of incidence than the upper wing will have upon completion of the RC model. That way, it is thought, the upper (and "more forward" wing) would stall first, and the lower wing would still have some lift on it, as a way to stay in the air, and bring the RC aircraft out of a stalled condition a small bit easier. Conversely, some RC fliers seem to think that it might be better to do the reverse, making the lower wing have a greater incidence angle, and making IT stall first, allowing the "more forward" upper wing to remain in a lifting condition. (That is a VERY old debate for RC model bipe builders...and the discussion never seems to end on that!)
- And, to create the full-blown "droop", with a possible desire to have a washed-out outer section of the Halby D.II's lower wing panel, bringing the trailing edge at the lower wing root area closer to the lower fuselage's lower longeron edge (read UPWARDS "to the lower longeron"), for a possibly more streamlined shape, and still having the possibly desirable washout at the wing's tip, would create a "droopy" look to the Halby D.II's lower wing trailing edge, that three-quarters of the photos of them in the Datafile certainly DO show, in the 59 photos on its pages that can show it.
- Please get in touch with me about this issue...there's a whole lot of photos in that Datafile that DO show the "droop" !
- Yours Sincerely,
- The PIPE!
- I am immensely impressed with your research and analysis of such a large number of photographs! There seems little doubt that the trailing edges of Halberstadt "D" type wings DID quite often droop - and to that degree I must confess that I stand corrected! My point about wing trailing edges that "flex" being likely to cause structural failure, not to mention lateral stability and control problems remains, however. Apparent deformation of Halberstadt "D" wings is MUCH more likely to have been caused by "sagging" due to rigging loosened by arduous war service, especially rough landings and violent manoeuvering, rather than being an intentional effect, caused by deliberate flexibility in the wing. Such sagging was a not uncommon feature of early aircraft, not just "Halbys". By your own analysis, quite a number of photographs that WOULD show the droop it it had been present, DON'T show any such thing, or show it to a much less marked degree. I can't see typical squadron mechanics of this period tightening rigging to the extent of "correcting" an INTENDED feature - it might just as well be the case that the photographs where droop is not evident are simply newer aircraft that have not as yet been thrown about very much. On the whole my original doubts about Grosz's statements remain, in this context.--Soundofmusicals (talk) 01:16, 26 July 2009 (UTC)
- Hi PIPE! - I have a copy of Grosz myself now. Relieved to find it isn't the source of the nonsense about "flexible wings" (wings that twist in the breeze make an aeroplane uncontrollable in the lateral plane, of course) but still can't find anything to give us a definite answer as to just why those lower edges (and in a few cases upper edges too) drooped! I now tend to think it must have been deliberate - a weakness in the wing structure doesn't sound likely, especially in such a heavily braced and notoriously sturdy structure. Deliberately rigging the wings with washout (increased incidence) near the roots was probably what did it. The different degrees of this (even allowing for tricks of perspective, some aircraft show a much more marked droop than others, and a few (especially ones in Turkish service) don't have any at all - some have similar droop in the top wing, while most show it only in the bottom) - all make me suspect it must have been something that was done in the field rather than in the factory (where you would expect things like this to be more uniform). And why was it done at all? To improve lateral control? The difference in form between the ailerons on different models makes me wonder if this was a problem with the Halberstadt D types that has never been properly documented. All this is (alas) speculation (or Original Research, as we call it in Wiki). All the same I think I have us just about covered now - referring to the photos, pointing out that it was there, and that we don't really know why! --Soundofmusicals (talk) 13:04, 12 June 2013 (UTC)
Are we sure Boelcke's aircraft was painted "prussian blue"? If we're going from the photograph, it should be noted that photographs from this period falsely darkened blue colors, making even light blue seem very dark. Ianbrettcooper (talk) 10:11, 21 February 2014 (UTC)