LLv34_Flanker Posted May 12, 2014 Author Posted May 12, 2014 S! Series 66 had for example 35kg lighter tail than the early series, according to Gordon & Khazanov book. The manufacturing was improved and they could cut the weight down without too much loss of structural integrity. I am pretty sure the same improvements were taken to the La-5 family right away.
bivalov Posted May 12, 2014 Posted May 12, 2014 Possibly they encountered the tail flutter hmmm, maybe, but i dont think so... but, of course, we just dont have all documents... and Lagg 3 development was abandoned in favor of the La-5 series so they did not waste effort in an aircraft that was being replaced or the design changes were incorporated in the La-5 series without wasting effort/resources to upgrade the Lagg 3 design. preference was given to la-5, definitely, but first la-5s it's ~mid of summer'42, meanwhile last known serie of lagg it's ~37 (somewhere in autrumn'42, i think), main design of these planes was almost same and each plane got almost identical improvements, if i not mistaken... i mean slats, retractable tail wheel for lagg (la-5 got retractable tail wheel, starting from ~4 series) etc, this is exactly s35 from this topic, which was produced in august'42... and 31 aviation plant still do laggs, and tried to change design in 42-43 > "66 series", which really can have another, lower dive limit (above i written about)... specific changes for la-5 type 37, it's another story, i think... so, personally i cant say that lagg not got any changes and was "orphan"... It looks like the in game Lagg 3 should have the higher dive limits and could encounter tail flutter. What do you think? personally i not think about dive seriously, even now, so, i only can write that before july'43 lagg-3 with modernised controls (balancers or aerodynamical compensation), apparently, had dive limit ~600-650 kph IAS, that in good agreement with all documental mentions'41-42... and looks like, at first, could be damaged controls, yes, but that mentioned in one of documents, which i posted - "Во всех известных случаях флаттера органов управления колебания конструкции нарастают сравнительно медленно и их можно погасить уменьшением скорости полета, для чего необходимо сбросить газ и взять ручку (штурвал) на себя" - ie it's not really dangerous, according to description of flutter...
MiloMorai Posted May 12, 2014 Posted May 12, 2014 The LaGG-3 was a dog > under powered and over weight, with some nasty flight characteristics. Initial La-5s used standard LaGG-3 airframes from the Gorky and Tbilisi assembly lines.
Crump Posted May 12, 2014 Posted May 12, 2014 and looks like, at first, could be damaged controls, yes, but that mentioned in one of documents, which i posted - "Во всех известных случаях флаттера органов управления колебания конструкции нарастают сравнительно медленно и их можно погасить уменьшением скорости полета, для чего необходимо сбросить газ и взять ручку (штурвал) на себя" - ie it's not really dangerous, according to description of flutter... In this case, the onset appears to be low frequency giving the pilot time to correct it by slowing down and maintaining control of the aircraft. That is not unheard of in aircraft but it does not mean the flutter was no big deal. If flutter is encountered, it weakens the structure and left uncorrected, will destroy it. http://www.youtube.com/watch?v=OhwLojNerMU
bivalov Posted May 13, 2014 Posted May 13, 2014 In this case, the onset appears to be low frequency giving the pilot time to correct it by slowing down and maintaining control of the aircraft. That is not unheard of in aircraft but it does not mean the flutter was no big deal. If flutter is encountered, it weakens the structure and left uncorrected, will destroy it. http://www.youtube.com/watch?v=OhwLojNerMU i again just mean that lagg not blows up/losing rudder, exactly at 651 kph IAS... and, finally, i got last document - "Курс переучивания на самолет ЛАГГ-3. Москва. 1942 год." (again, thx to Wad) - it's about early lagg-3 with m-105p/pa, and there mentioned exactly 550 IAS/600 IAS, like and in manual'43... plus, i found mention, about test of lagg-3 with aerodynamical compensation and modernised elevators (in fact, i think, that it's just test of lagg with sh-37) - "1 сентября 1942 г. ЛаГГ-3 с М-105ПФ и винтом ВИШ-61П закончил государственные испытания, которые проходили с 25 августа. На машине имелись доработанные рули высоты и поворота с аэродинамической компенсацией, снизившей нагрузки на органы управления, частично убирающийся костыль и пять бензобаков. На крыле установили бомбодержатели и предкрылки. Кроме 37-мм пушки Ш-37 самолет вооружался одним пулеметом БС с боекомплектом 140 патронов. Испытания показали, что применение предкрылков и аэродинамической компенсации рулей облегчило управление самолетом (хотя управление рулем поворота оставалось еще довольно тяжелым); время виража, несмотря на увеличение полетного веса, сохранилось прежним; улучшилась поперечная устойчивость. Самолет без проблем пикировал под углом 60° с приборной скоростью 650 км/ч. Наивыгоднейшими для атаки углами были 30 - 40°. Стрельба из 37-мм пушки не раскачивала машину и, соответственно, не влияла на точность прицеливания, что было особенно важно для борьбы с бронетехникой." there written that at 1 september, tests completed, this plane with aerodynamical compensation and with modernised elevators, now has better handling (but still hard to use rudder), plane - without problems - can dive with 60°/650 IAS... btw, looks like, it's document which was used by devs, for BOS... and, although, i not sure in these modernized elevators, it's early changes exactly for lagg, and when, or they identical with changes for la-5 (plane was heavier and had problems with handling in dive)... but, in total, i think, all our conclusions is correctly, modernised planes has dive limit = 650 kph IAS...
LLv34_Flanker Posted May 13, 2014 Author Posted May 13, 2014 (edited) S! You can dive excess of 800km/h IAS/90deg in BoS before anything happens. There is no fluttering. Quite a bit above the specified dive limit value. Interesting the other report with LaGG-3 VK-105PF engine, thanks for posting Translators just do not work properly for Russian Edited May 13, 2014 by LLv34_Flanker
Crump Posted May 13, 2014 Posted May 13, 2014 but, in total, i think, all our conclusions is correctly, modernised planes has dive limit = 650 kph IAS. If that is what's in the Pilot's Operating Handbook, then it was cleared for that q-limit! Translators just do not work properly for Russian You have to break it down into smaller chunks. It is talking about testing the 37mm equipped Lagg 3 series prototype. The aircraft had the 37 mm cannon and equipment for rockets. This was the first one equipped with handley page automatic slats AFAIK. The aircraft was given rudder and elevator modifications and at a 60 degree angle reached 650 kph IAS in a dive without incident. I don't know how applicable this is to the other Lagg 3 series and would check the Pilot Operating Instructions for the specific type. i again just mean that lagg not blows up/losing rudder, exactly at 651 kph IAS. No, that is just when the onset of flutter can occur.
bivalov Posted May 13, 2014 Posted May 13, 2014 You can dive excess of 800km/h IAS/90deg in BoS before anything happens. There is no fluttering. Quite a bit above the specified dive limit value. i know about this, and it's strange, although, for fuselage is possibly... but looks like not for controls... Interesting the other report with LaGG-3 VK-105PF engine, thanks for posting no problem, but, looks like that information is not a secret, and this is have in some translations... If that is what's in the Pilot's Operating Handbook, then it was cleared for that q-limit! yep, dive tests in 1941 + manual for pilot (september'42)... You have to break it down into smaller chunks. It is talking about testing the 37mm equipped Lagg 3 series prototype. The aircraft had the 37 mm cannon and equipment for rockets. This was the first one equipped with handley page automatic slats AFAIK. aerodynamical compensation, according to some books, it's lagg s23 and later... i think, s29 was equipped with this rudder, definitely, plus known fact that some planes of s29 was equipped with slats, although, as standard only starting from s35 and la-5... and in quote only mentioned, that plane with sh-37 starting from beginning, was equipped with all improvements... and, btw, rockets for any fighters (except some old types and L-L), not can be installed starting from may'42... in game it's "what if", in fact... The aircraft was given rudder and elevator modifications and at a 60 degree angle reached 650 kph IAS in a dive without incident. i checked these "elevator modifications", this is very similar on changes for la-5, there a bit bigger area of elevator now + another trimmer, so, 650 IAS can be absolutely correctly exactly for planes with aerodynamical compensation+elevator modifications... for planes, only with aerodynamical compensation, because high loads on stick, in dive, like for heavy la-5, more correctly can be exactly 600 IAS... but, maybe, 650 IAS correctly for all modernized planes, with any changes... I don't know how applicable this is to the other Lagg 3 series and would check the Pilot Operating Instructions for the specific type. better will be to carefully check all changes for lagg, because, besides known manual'43, and these manual'42 + retraining manual'42, there no any other manuals... if i not mistaken, or need to carefully check "chronology", but i not sure that there could be new quotes...
Crump Posted May 14, 2014 Posted May 14, 2014 yep, dive tests in 1941 + manual for pilot (september'42)... The timeline..... Let me see if I got this right, bivalov. September 1942 the Lagg 3 is cleared for 650kph IAS. One year later, the September 1943 manual states the dive limit is 600kph IAS IF the controls are aerodynamically balanced to prevent flutter and 550kph IAS if they are not balanced. So the dive limit was lowered over the lifecycle of the design.
Crump Posted May 14, 2014 Posted May 14, 2014 I think there is more to the story. On page 26 in Yefim Gordon's "Lavochkin's Piston-Engined Fighters" it discusses the poor results of dive testing in the summer of 1941 limiting the aircraft to 600 kph IAS for aerodynamically balanced controls and 550kph IAS for unbalanced controls. Those same instructions are repeated in the September 1943 Operating Instructions. Do you have an earlier Operating Manual that specifies the dive limit is 650kph IAS for the Lagg 3? That would make things much clearer.
bivalov Posted May 14, 2014 Posted May 14, 2014 September 1942 the Lagg 3 is cleared for 650kph IAS. yes... One year later, the September 1943 manual states... i think, not really "states", because looks like it's just full copying of first known manual (early 42), word in word... by which reasons, i cant say... meanwhile, now we know about all changes in design (1 or 2 balancers on rudder/or aerodynamical compensation/elevators) and manual with 650 IAS (sept'42)... plus this report, about testing of a bit heavier plane, at 650 IAS... IF the controls are aerodynamically balanced to prevent flutter and 550kph IAS if they are not balanced. no, 600 IAS - if rudder equipped with 1 or 2 weight balancers, for old type of rudder, "aerodynamical compensation" it's just a bit another rudder... 550, if without any changes, yes... So the dive limit was lowered over the lifecycle of the design. definitely, no, because all these facts, above... but and fact, of course, that manual'43 copies early manual'42, by unknown reasons... On page 26 in Yefim Gordon's "Lavochkin's Piston-Engined Fighters" yep, this is old compilation of russian books, meanwhile i given almost all original documents and a bit more, like original manuals, for better understanding... it discusses the poor results of dive testing in the summer of 1941 limiting the aircraft to 600 kph IAS for aerodynamically balanced controls and 550kph IAS for unbalanced controls. yes, all like in our topic, but error is "aerodynamically balanced controls" - it's for late series, before were 1 or 2 weight balancers, on rudder... i given links above, so, now you can see this in attached picture (2 balancers, 1 balancer, aerodynamical compensation, but in series can be error)... Do you have an earlier Operating Manual that specifies the dive limit is 650kph IAS for the Lagg 3? That would make things much clearer. of course, no, even retraining manual'42 and manual'42 (september-oktober), it's absolutely exclusive information... but why? looks like you just not understand my english? i think that almost all clear, and only need dates, when exactly were installed all changes, on serial planes...
LLv34_Flanker Posted May 14, 2014 Author Posted May 14, 2014 S! Tht picture tells more than 1000 words, Bivalov Thanks! So the Finns tested the Series 35 that had the latest modification on the tail. The earlier models Finns had were, if I recall right, Series 4 and 28. And Finns also installed leading edge slats on these 2 other planes as they were on Series 35. Good info Bivalov, makes more sense when we see more of the texts
Crump Posted May 14, 2014 Posted May 14, 2014 Hi bivalov, I understand the Russian. Using results from a test report is not the right thing to do. What is approved for operational use is clearly printed in the Operating Instructions. If there is a Pilot's Operating Instruction or even a technical order then we can say the aircraft used in the VVS would be approved for 650 kph. The Operating Instructions dated 10 July 1943 do not distinguish except to note balanced aircraft can dive to 600 kph IAS and unbalanced to 550 kph IAS. They instruct the pilot to keep the propeller rpm to 2800 rpm and to use elevator trim and carefully recover as to not overload the aircraft. The altitude loss in a 60 degree dive to 600 kph IAS is 1400 meters. It is pretty normal stuff and there is no provision for distinguishing the 3 types of rudder balance. Thanks! Crumpp
bivalov Posted May 14, 2014 Posted May 14, 2014 Good info Bivalov, makes more sense when we see more of the texts although, i think that's not secret (some could be in compilations of Gordon or "in action")... looks like, yes, absolutely definitely... The earlier models Finns had were, if I recall right, Series 4 and 28. if you can get docs about these series, i think, you will be "LLv34_LaGG-3"... I understand the Russian. it's good... Using results from a test report is not the right thing to do. What is approved for operational use is clearly printed in the Operating Instructions. If there is a Pilot's Operating Instruction or even a technical order then we can say the aircraft used in the VVS would be approved for 650 kph. i know, i mean that information in manuals is based exactly on testing information, that we see on example of lagg, and in new documents/manuals... end of tests of lagg s34, with sh-37 (1 september) > manual'42 (13 september-23 october)... btw, all time need to remember, that ussr is not germany or usa... The Operating Instructions dated 10 July 1943 do not distinguish except to note balanced aircraft can dive to 600 kph IAS and unbalanced to 550 kph IAS. hmm, let me - i also know russian... - again correct you, manual'43 absolutely FULL copies retraining manual'42 (in description of dive), for early lagg with m-105pa... and in each manual mentioned BALANCERS on rudder, but not aerodynamical compensation, that is another type... but, in total, i understood your point of view, it's very logically and possibly... It is pretty normal stuff and there is no provision for distinguishing the 3 types of rudder balance. not sure, but, maybe... in fact, i second time forgot to say, that - also, by my opinion - could be that for lagg with any type of balanced rudder, correctly is 600 IAS... and 650 IAS is correctly exactly for planes with aerodynamical compensation + new elevators - looks like, time of this improvement shows that it's ~s35 and later - not much planes, in fact, because last known serie it's 37... although, old planes could be modernised, and personally i just don't know, exactly which series was equipped with "aerodynamical compensation + new elevators"... ie this is why, besides other reasons above, manual'43 repeats early manual'42...
LLv34_Flanker Posted May 14, 2014 Author Posted May 14, 2014 (edited) S! Will ask if there is more data on the other two LaGG-3's, LG-1 and LG-2. At least they got the slats installed by Finns. Another very interesting plane Finns got from VVS as captured was P-40M Warhawk. It was in good shape and flown by Finnish pilots. They seemed to like it, Kyösti Karhila mentioned flying it in 1944. Not sure if there is any data of it anywhere. It was sadly scrapped after war, like the LaGG-3's Edited May 14, 2014 by LLv34_Flanker
Crump Posted May 14, 2014 Posted May 14, 2014 (edited) BALANCERS on rudder, but not aerodynamical compensation All of these are balancer's, or more correctly aerodynamic balancing devices. The first two are mass balances. The first one is not as thick as the second mass balance so they increased weight, strengthened the device, or both. The third is a horn balance. All three do exactly the same thing aerodynamically and the main purpose of adding them is to prevent flutter. You can even mass balance by increasing the hinge size and adding mass to the leading edge of the control surface so that it is unnoticeable from the exterior!! It is all the same thing aerodynamically. They all use inertia and aerodynamic forces to counter flutter. Edited May 14, 2014 by Crump
Crump Posted May 14, 2014 Posted May 14, 2014 not sure, but, maybe... in fact, i second time forgot to say, that - also, by my opinion - could be that for lagg with any type of balanced rudder, correctly is 600 IAS... and 650 IAS is correctly exactly for planes with aerodynamical compensation + new elevators - looks like, time of this improvement shows that it's ~s35 and later - not much planes, in fact, because last known serie it's 37... although, old planes could be modernised, and personally i just don't know, exactly which series was equipped with "aerodynamical compensation + new elevators"... ie this is why, besides other reasons above, manual'43 repeats early manual'42... It looks like you are saying: Lagg 3 as per the Operating Instructions is 600kph IAS. Lagg 3-37 might be 650kph IAS. If you are saying that then I agree with you. I also agree that Lagg 3-37 could have very well been cleared for 650kph IAS for the q-limit. Does anybody have a copy of the Operating Instructions for that type? Without seeing the Operating Instructions though we are just guessing. The older Lagg 3 serials may very well have been "modernized" to raise the q-limit to 650kph IAS. As second echelon aircraft replaced by the La-5 series and all Lagg 3 production cancelled (IIRC) I don't see why it would be worth the effort. A trainee is not going to learn anything going 50 kph IAS faster. Taking an airplane to the limit and controlling it at the edge is the same....only the limits are different! That does not mean it did not happen.
bivalov Posted May 14, 2014 Posted May 14, 2014 Will ask if there is more data on the other two LaGG-3's, LG-1 and LG-2. At least they got the slats installed by Finns. will be good, of course, but this is just our historical interest... and i heard about slats for these early planes, yes... They seemed to like it, Kyösti Karhila mentioned flying it in 1944. interesting... It was sadly scrapped after war, like the LaGG-3's well, i can understand this, but... All of these are balancer's, or more correctly aerodynamic balancing devices. All three do exactly the same thing aerodynamically and the main purpose of adding them is to prevent flutter. It is all the same thing aerodynamically. They all use inertia and aerodynamic forces to counter flutter. don't need to explain, that also i know, in fact, all changes in aerodynamics, but there weight balancers (aerodynamical changes) or aerodynamical compensation (looks like роговая)... and in early/late manuals'42/43, one quote about these weight balancers... but i not sure in effectiveness of each type, so, could be that aerodynamical compensation was better = 650 IAS... It looks like you are saying: Lagg 3 as per the Operating Instructions is 600kph IAS. Lagg 3-37 might be 650kph IAS. If you are saying that then I agree with you. i said - lagg with weight balancers/aerodynamical compensation (роговая) = 600 IAS (most likely), or 650 IAS exactly for aerodynamical compensation (doubt)... lagg with aerodynamical compensation+changed elevators = 650 IAS, definitely, and NO matter, this is lagg-3-37 or lagg with typical weapon... I also agree that Lagg 3-37 could have very well been cleared for 650kph IAS for the q-limit. Does anybody have a copy of the Operating Instructions for that type? Without seeing the Operating Instructions though we are just guessing. lagg-3 with sh-37 heavier on ~150 kg, but even this plane showed 650 IAS, without problems, and, looks like typical late series has this speed too... (and lagg-3 with sh-37/ns-37 it's not really mass type of this plane, i think not was any manuals for this plane, or similar planes... dont know, what you want, great that we have what we have now)... and, finally, very fast search gives that - "10 июня 1942 вышел приказ НКАП N 432сс "О самолетах ЛаГГ-3": "В исполнение постановления ГКО N ГОКО-1895 от 7 июня 1942 об обеспечении управления самолетом ЛаГГ-3 и улучшения его летных данных: 1. Зам. нач. ПГУ Шиц, директору завода 21 Гостинцеву и ГК С.А.Л. ввести на самолетах ЛаГГ-3 предкрылки, элероны и рули с улучшенной компенсацией и убирающийся костыль с выпуском всех самолетов ЛаГГ-3 с этими улучшениями с 1 июля 1942 2. Директору завода 31 Агаджанову ввести на всех самолетах ЛаГГ-2 улучшения, указанные в п. 1 настоящего приказа с 15 июля с.г. (1557,8)." there written about - slats, ailerons, rudder (or rudder+elevators) with "better compensation" and retractable tail wheel - which planned for ALL laggs, starting from 1 july'42 (21 aviation plant)/15 july'42 (31 aviation plant in Tbilisi)... ie it's typical soviet gradual improvement, and almost confirmation of s34-35 as fully modernized laggs-3... and, looks like, it's confirmation of 650 IAS for aerodynamical compensation+changed elevators, and why manual'42 repeats retraining manual'42...
Crump Posted May 14, 2014 Posted May 14, 2014 lagg with aerodynamical compensation+changed elevators = 650 IAS, definitely, and NO matter, this is lagg-3-37 or lagg with typical weapon... Where is that published in a Lagg 3 series Operating Instructions. Not quotes from a aeronautical sciences agency or manufacturers test report. What does the Operating Instructions for the type say? Can you post the page? there weight balancers (aerodynamical changes) or aerodynamical compensation (looks like роговая) I am sure you know that they all do the same thing. They move the control surface CG closer to the hinges....... Does not matter which one you choose.
bivalov Posted May 14, 2014 Posted May 14, 2014 some important little details, from documents:1 manual'42 - dates which i found, it's 10 september'42, 12 september'42, 13 september'42 and 23 october'42 - ie it's timeline of offical approval, by all chiefs + "подписано в печать 2.X.42 г."2 this manual for all combat pilots, and recommended for scools/reserve regiments... 3 this manual'42, like and manual'43, for laggs with m-105p/pa and m-105pf... 4 in section about dive, type of rudder not mentioned, just - "пикирование разрешается производить до скорости 650 км/час по прибору" - that's all... 5 "курс переучивания и боевой подготовки летного и технического состава на самолете лагг-3 (1942)", no dates, besides year...6 according to full text, it's very early document, when lagg was new type, and just one of very mass types...7 so, mentioned shkas/UBS, and only m-105p...8 for example, turn time is 22-23 seconds... 9 manual'43 - "подписано к печати 15.9.43"10 turn time - 22-23 seconds - ie like in retraining manual'42...several interesting quotes, from "Rodionov's Chronology"... "На 1 января 1943 в строю было: ЛаГГ-3 - 1514" "Потери за 1943 (ЛаГГ-3) январь февраль март апрель май июнь июль92 62 151 124 78 61 42август сентябрь октябрь (всего)19 67 62" "1 июня 1943 года... Данные по дальности и продолжительности полета истребительных самолетов, находящихсяна вооружении ВВС и трофейных, при полете до полного выгорания горючего.Лагг-3 с М-105П(3-х баковый)Лагг-3 с М-105ПФ"
bivalov Posted May 14, 2014 Posted May 14, 2014 Where is that published in a Lagg 3 series Operating Instructions. what you mean? i again repeat, in according to all information which i have, was something like this... What does the Operating Instructions for the type say? Can you post the page? absolutely nothing, i told you before, and i think it's not really typical for soviet manuals... I am sure you know that they all do the same thing. of course, i know this, and i told you about concrete types in all manuals... why you think that i dont know, well, i dont know... Does not matter which one you choose. not sure, aerodynamical could be better, but looks like just similar...
Crump Posted May 14, 2014 Posted May 14, 2014 (edited) "10 июня 1942 вышел приказ НКАП N 432сс "О самолетах ЛаГГ-3": "В исполнение постановления ГКО N ГОКО-1895 от 7 июня 1942 об обеспечении управления самолетом ЛаГГ-3 и улучшения его летных данных: 1. Зам. нач. ПГУ Шиц, директору завода 21 Гостинцеву и ГК С.А.Л. ввести на самолетах ЛаГГ-3 предкрылки, элероны и рули с улучшенной компенсацией и убирающийся костыль с выпуском всех самолетов ЛаГГ-3 с этими улучшениями с 1 июля 1942 2. Директору завода 31 Агаджанову ввести на всех самолетах ЛаГГ-2 улучшения, указанные в п. 1 настоящего приказа с 15 июля с.г. (1557,8)." Ok but none of this says the dive limit is now 650 Kph IAS. It just orders the slats and control surface balancing into production. In other words, I don't see an engineering reason why they would approve one for a faster q-limit than over another. It does not mean there is not one, it is just not in the balancing choices. The slats have no effect on q-limits. So What else did they do? Did they make changes to the hinges? Stabilizer sizing? Any of those things? We can account for ALL the balancing effects in the 600 kph IAS limit for balanced controls and 550 kph IAS for unbalanced controls. It is not hard to balance control surfaces and I just don't see them making a mistake the first time in the balancing itself. I think the rod the first weight was attached too might have been too thin and the horn balancing is cheaper, lighter, and easier to manufacture than either mass balance. That is why I would like to see the Operating Limitations that are published for the pilots to use. Edited May 14, 2014 by Crump
Crump Posted May 14, 2014 Posted May 14, 2014 absolutely nothing, i told you before, and i think it's not really typical for soviet manuals... If it is not published in the Operating Manual as 650 kph IAS dive limit, then it was probably never approved for Operational use at 650 kph IAS. That does not mean the case is closed. It just makes it very unlikely.
bivalov Posted May 14, 2014 Posted May 14, 2014 Ok but none of this says the dive limit is now 650 Kph IAS... and control surface balancing into production. there clearly mentioned - "рули с улучшенной компенсацией" - and i think, that also was need more effort to pullout > modernized elevators, but absolutely not sure... so - was planned "рулИ с улучшенной компенсацией" (mid of summer'42) > report about lagg-3-37 with known "доработанные рули высоты и поворота с аэродинамической компенсацией" (end of summer - 1 sept'42) > instead 600 IAS, now manual'42 (sept'42) with 650 IAS... plus, also i found now confirmations about modernized elevators - "Летный состав строевых частей отмечает, что с-т ЛаГГ-3 уступает неприятельским истребителям главным образом в... простоте техники пилотирования (имеются в виду с-ты с неизмененными рулями). После установки на с-т измененных рулей техника пилотирования упростилась (нагрузки на рули стали незначительными)" "Указом ГКО от 7 июня 1942 года завод № 21 должен был ставить на ЛаГГи-3 автоматические закрылки и убирающееся хвостовое колесо, а также элероны и рули высоты с улучшенной балансировкой."
bivalov Posted May 14, 2014 Posted May 14, 2014 If it is not published in the Operating Manual as 650 kph IAS dive limit, then it was probably never approved for Operational use at 650 kph IAS. i AGAIN repeat - 1 manual'42 - dates which i found, it's 10 september'42, 12 september'42, 13 september'42 and 23 october'42 - ie it's timeline of offical approval, by all chiefs + "подписано в печать 2.X.42 г." 2 this manual for all combat pilots, and recommended for scools/reserve regiments.. 3 this manual'42, like and manual'43, for laggs with m-105p/pa and m-105pf... 4 in section about dive, type of rudder not mentioned, just - "пикирование разрешается производить до скорости 650 км/час по прибору" - that's ALL... other conclusions and information + my opinion, ABOVE... looks like, nothing to say, more...
Crump Posted May 14, 2014 Posted May 14, 2014 Hi bivalov, I am totally confused!! It looks like you are saying here that the dive limit is 650kph IAS in the Инструкции лётчику here: i AGAIN repeat -1 manual'42 - dates which i found, it's 10 september'42, 12 september'42, 13 september'42 and 23 october'42 - ie it's timeline of offical approval, by all chiefs + "подписано в печать 2.X.42 г."2 this manual for all combat pilots, and recommended for scools/reserve regiments..3 this manual'42, like and manual'43, for laggs with m-105p/pa and m-105pf...4 in section about dive, type of rudder not mentioned, just - "пикирование разрешается производить до скорости 650 км/час по прибору" - that's ALL... other conclusions and information + my opinion, ABOVE... looks like, nothing to say, more... But then there is no instruction allowing 650 kph IAS dive limit in the Инструкции лётчику here: what you mean?i again repeat, in according to all information which i have, was something like this...absolutely nothing, i told you before, and i think it's not really typical for soviet manuals... I apologize and I am not trying to be difficult. It is just two conflicting pieces of information.
bivalov Posted May 15, 2014 Posted May 15, 2014 But then there is no instruction allowing 650 kph IAS dive limit in the Инструкции лётчику here: I apologize and I am not trying to be difficult. It is just two conflicting pieces of information. you asked about type - "What does the Operating Instructions for the type say?" - and i written that in manuals no types, besides planes with m-105p or m-105pf, so, no specific information for lagg-3-37... dive limit is 650 IAS...
MiloMorai Posted May 15, 2014 Posted May 15, 2014 If the dive limit is 550kph, how could the LaGG-3 have a max speed of 570kph @ 4000m and 562kph @ 5000m? Also was the dive limit speed the same from max altitude to near the ground? example Flying Limitations of the Spitfire IX (from Pilot's Notes)Maximum speeds in m.p.h I.A.S.Diving (without external stores), corresponding to a Mach No. of .85: Between S.L. and 20,000 ft. 450 20,000 and 25,000 ft. 430 25,000 and 30,000 ft. 390 30,000 and 35,000 ft. 340 Above ..................35,000 ft. 310 Bf109 Up to 3 km (9,842 ft.) 750 km/h. (466 m.p.h.) At 5 km (16,404 ft) 700 km/h. (435 m.p.h.) At 7 km (22,965 ft) 575 km/h. (357 m.p.h.) At 9 km (29,527 ft) 450 km/h. (280 m.p.h.) At 11 km (36,089 ft) 400 km/h. (248 m.p.h.)
bivalov Posted May 15, 2014 Posted May 15, 2014 (edited) If the dive limit is 550kph, how could the LaGG-3 have a max speed of 570kph @ 4000m and 562kph @ 5000m? 550 kph IAS = if i not mistaken, is ~620-630 kph TAS, and when starting problems... Also was the dive limit speed the same from max altitude to near the ground? interesting... never seen, but looks like there also could be something like this... although, heavy lagg-3 it's not plane of high altitudes, so, maybe, this is just not mentioned... Edited May 15, 2014 by bivalov
Crump Posted May 15, 2014 Posted May 15, 2014 If the dive limit is 550kph, how could the LaGG-3 have a max speed of 570kph @ 4000m and 562kph @ 5000m? Also was the dive limit speed the same from max altitude to near the ground? example Flying Limitations of the Spitfire IX (from Pilot's Notes) Maximum speeds in m.p.h I.A.S. Diving (without external stores), corresponding to a Mach No. of .85:Between S.L. and 20,000 ft. 450 20,000 and 25,000 ft. 430 25,000 and 30,000 ft. 390 30,000 and 35,000 ft. 340 Above ..................35,000 ft. 310 Bf109Up to 3 km (9,842 ft.) 750 km/h. (466 m.p.h.) At 5 km (16,404 ft) 700 km/h. (435 m.p.h.) At 7 km (22,965 ft) 575 km/h. (357 m.p.h.) At 9 km (29,527 ft) 450 km/h. (280 m.p.h.) At 11 km (36,089 ft) 400 km/h. (248 m.p.h.) See bivalov's explanations on indicated airspeed vs true airspeed. The True airspeed is a function of density altitude varying at the reciprocal of the square root of the density ratio. Many aircraft had a single q-limit dive speed at the beginning of World War II. The transonic realm and Mach effects were not well known and largely unexplored in manned flight. See: Crump says: The limits may not be actually flight tested is very true as the result of the engineers being right is catastrophic for the poor pilot. However, the limits are set by very real parameters. Dynamic pressure limits were well known and not hard to calculate in the 1940's. Dynamic pressure limits (called q-limits) usually manifest themselves in the form of flutter which can destroy an aircraft in the blink of an eye. Where designers ran into trouble during the World War II era was in the transonic realm. Several designs ran into compressibility issues (mach limits) long before their calculated Dynamic pressure limits were encountered resulting in fatalities. They ran into these issues at a lower velocity than what the Dynamic pressure limits allowed. That is because compressibility is a function of true airspeed resulting from the aircraft interaction with normal shock formation and not the aerodynamic forces used to determine the q-limits. Subsequently at high density altitudes one could stay well within the q-limits and exceed the mach limits. Because of the lack of transonic realm knowledge, a World War II design is more likely to run into trouble below the established dive limits rather than being able to exceed them. Looking at the Lagg 3 Series 35, 600 kph comes out to about mach .76 which is one the lower side but still in normal range for a World War II fighter so I see were your opinion comes from. Exceptions are rare but they do happen. Many designs in World War II started out with blanket limits such as the 750kph IAS dive limit of the Bf-109E. This 750kph IAS was a calculated q-limit dive speed. The Germans lost some aircraft in dives and upon actual flight testing found out the aircraft had directional stability issues. One of the effects of normal shock formation is to move CG back changing the stability margin. They restricted the initial blanket 750kph to lower the limit at higher altitudes to avoid this compressibility effect and made design changes to increase directional stability. The airplane ran into compressibility effects resulting in a lowering of the established q-limit dive speed. http://forum.il2sturmovik.com/topic/3883-lagg-3-series-35/?p=114716 Crumpp says: The airplane ran into compressibility effects resulting in a lowering of the established q-limit dive speed. That is exactly what it looks like happened here with the Lagg 3 series. The early manuals say 650 kph IAS while the latest manual I am aware of says: Appears to lower the limits to 600 kph IAS for balanced control surfaces and 550kph IAS for unbalanced control surfaces. No distinction is made for the 3 methods used to achieve balance. Bivalov, what are the exact dates for the 1943 manuals you mention?
Crump Posted May 15, 2014 Posted May 15, 2014 (edited) Maximum speeds in m.p.h I.A.S. Diving (without external stores), corresponding to a Mach No. of .85: I also sure the developers are aware of the state of compressible aerodynamics in World War II and will refrain from using any nations "mach values". The RAE's Mach 9.0 could easily be TSAGI's Mach .7....... Most likely they will go from CAS to EAS using a universal compressibility correction and not fool around with 1940's compressible aerodynamics expressions. Edited May 15, 2014 by Crump
LLv34_Flanker Posted May 15, 2014 Author Posted May 15, 2014 S! Keep it on LaGG-3 please So far good info and good discussion
Crump Posted May 15, 2014 Posted May 15, 2014 you asked about type - "What does the Operating Instructions for the type say?" - and i written that in manuals no types, besides planes with m-105p or m-105pf, so, no specific information for lagg-3-37... I got it now. I think getting the timeline on the manuals is most important to finding our answer on Lagg 3 q-limits.
LLv34_Flanker Posted May 16, 2014 Author Posted May 16, 2014 S! Got some tidbits of LG-1, and earlier variant of LaGG-3 tested and used by FiAF. It had leading edge slats installed by Finns, not at time of capture. Soon posting 1
LLv34_Flanker Posted May 16, 2014 Author Posted May 16, 2014 S! Here it goes. Tests conducted at end of august 27.8.1943 and early september 1.9.1943. Enjoy! 1. 360deg turn with full power and maximum speed Test conducted 1.9.1943 Weather: air pressure 1007.1mbar, temperature +15,3'C, wind 360deg, strength 1 beaufort, clouds 10/10 Altitude Start speed End speed Time 2000m 400km/h 360km/h 23" 4000m 370km/h 330km/h 25" 6000m 300km/h 260km/h 26" 2. 360deg turn on cruise power and cruise speed Test conducted 1.9.1943 Weather: air pressure 1007.1mbar, temperature +15,3'C, wind 360deg, strength 1 beaufort, coulds 10/10 Altitude Start speed End speed Time 2000m 350km/h 310km/h 26" 4000m 340km/h 300km/h 26" 6000m 270km/h 230km/h 27" 3. Acceleration and deceleration Test conducted 27.8.1943 Weather: air pressure 1007.1mbar, temperature +20,2'C, wind 135deg, strength 2 beauforts, clouds 8/10 ACCELERATION Altitude Start speed End speed Time 2000m 220km/h 400km/h 55" 4000m 250km/h 370km/h 45" 6000m 200km/h 300km/h 42" DECELERATION Altitude Start speed End speed Time 2000m 400km/h 220km/h 25" 4000m 370km/h 250km/h 17" 6000m 300km/h 200km/h 18" More to come 1
LLv34_Flanker Posted May 16, 2014 Author Posted May 16, 2014 (edited) S! Here some maneuvering tests and such..Hope you like 4. Climb from level flight at maximum power Test conducted 27.8.1943 Weather: air pressure 1007.1mbar, temperature +20,2'C, wind 135deg, strength 2 beauforts, clouds 8/10 Starting altitude Ending altitude Start speed End speed Time 2000m 2750m 400km/h 220km/h 11" 4000m 4650m 370km/h 210km/h 10" 6000m 6500m 300km/h 200km/h 11" 5. Turning radius, pull out from a dive, speed 600km/h IAS Test conducted 27.8.1943 Weather: air pressure 1007.1mbar, temperature +20,2'C, wind 135deg, strength 2 beauforts, clouds 8/10 Starting altitude Start of pull out Altitude after pull out Time 4000m 2800m 2100m 10" 4000m 2700m 2060m 10" First dive from starting speed 350km/h, dive started with a half roll, dive angle 85deg. Second dive from 300km/h, nose pushed down, dive angle 85deg. 6. 180deg Immelmann turn Test conducted 26.8.1943 Weather: air pressure 1006.8mbar, temperature +17,2'C, wind 290deg, strength 2 beauforts, clouds 9/10 Starting altitude End altitude Starting speed End speed Time Max. power 2000m 2700m 400km/h 210km/h 18" Cruise power 2000m 2500m 360km/h 210km/h 17" Max. power 4000m 4600m 370km/h 210km/h 15" Cruise power 4000m 4450m 340km/h 210km/h 14" Max. power 6000m 6400m 300km/h 190km/h 17" Cruise power 6000m 6300m 270km/h 190km/h 16" Turns have been performed at 70-80deg bank angle. Excess use of elevator causes the plane to stall through and turning slows down considerably. Plane stalls through evenly and controls lighten up. If pull is increased plane starts to shudder and enter a spin; turn has to be stopped. A 90deg dive can not be performed with the plane as the propellor constant speed unit does not work, causing engine to over-RPM dangerously. Greatest angle of dive is roughly 85deg. Plane is stable in the dive up to 575km/h. After that increasing shake is encountered. Dive has to be started by pushing nose down or from a turn. Starting from a half roll results in the engine going to over-RPM. Tests flown by Warrant Officer L. Lautamäki. EDIT: Added both documents to this last post as could not attach to previous one. Hope you like! Edited May 16, 2014 by LLv34_Flanker 1
Crump Posted May 16, 2014 Posted May 16, 2014 Plane is stable in the dive up to 575km/h. After that increasing shake is encountered. Dive has to be started by pushing nose down or from a turn. Interesting. That increasing shake beginning at 575 kph is probably due to flow separation aft of the normal shock and not flutter.
LLv34_Flanker Posted May 16, 2014 Author Posted May 16, 2014 S! I corrected a bit the translation. It says that after 575km/h the plane starts to shake increasingly/more strongly.
Crump Posted May 16, 2014 Posted May 16, 2014 Flutter generally manifest's itself as a vibration in the controls first and progresses to a buzz in the airframe. While pilots have encountered flutter and survived, it is not very common. http://11hc.44rf.com/manuals/flight_testing/sport_pilot_mag_articles/test_flight_danger_zone_2006_11_15.pdf In other words, it is not perceived from the cockpit as "shaking" or buffeting. That is generally flow separation due to normal shock formation. ALL normal shock will cause flow separation behind it. That is why airplanes shake and buffet at high speed.
Sternjaeger Posted May 17, 2014 Posted May 17, 2014 Flutter generally manifest's itself as a vibration in the controls first and progresses to a buzz in the airframe. While pilots have encountered flutter and survived, it is not very common. http://11hc.44rf.com/manuals/flight_testing/sport_pilot_mag_articles/test_flight_danger_zone_2006_11_15.pdf In other words, it is not perceived from the cockpit as "shaking" or buffeting. That is generally flow separation due to normal shock formation. ALL normal shock will cause flow separation behind it. That is why airplanes shake and buffet at high speed. No Crump, you're confusing two different things. When your control surfaces start fluttering you don't experience vibration, it whips the wings and SHAKES the airframe, and it can be a relatively common occurrence. Whilst it is advisable not to reach flutter speed, there are several stages to it, more or less safe to "explore", and the intensity and frequency increases with the airspeed. https://www.youtube.com/watch?v=qfkkiDsEXUA note that wing flutter is peculiar to the wing/surface design, so it doesn't occur on the same airspeed for all aircraft of course. I think it's safe to say (and others will probably confirm) that the 575km/h shaking in a dive that the manual refers to describes flutter speed.
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