От bedal
К Robert
Дата 21.05.2013 23:12:49
Рубрики Современность; ВВС;

не "разные", а "положительное продольное V"

и лететь будет вполне устойчиво. Но клевать будет при срыве сильно. Однако для барражирующей беспилотки это может быть и совершенно несущественно - ей пилотаж не делать.

Зато отличные показатели эффективности можно получить.
От Robert
К bedal (21.05.2013 23:12:49)
Дата 21.05.2013 23:28:45

Это одно и то же:

угол атаки передней плоскости больший, чем у задней называется "продольным положительным V".

>и лететь будет вполне устойчиво. Но клевать будет при срыве сильно. Однако для барражирующей беспилотки это может быть и совершенно несущественно - ей пилотаж не делать.

>Зато отличные показатели эффективности можно получить.

За счет чего? Вы ставите в потоке одно (из двуx) крыльев на угле атаки далеком от угла соответствующего максимальному качеству.

Нужно качество - так планеристы не дураки. Делать, как у рекордныx планеров: одно крыло большого удлиннения, длиннющий xвост, и маленькое (по площади) ГО на нем. Проверено множество раз: все остальные варианты xуже.
От bedal
К Robert (21.05.2013 23:28:45)
Дата 22.05.2013 11:57:20

не совсем так

То, что Вы написали - верно при одинаковых профилях на крыльях, что вовсе не обязательно. На биплан-тандемах вообще возможно столько разных эффектов...

Сделать планерный размах и длину на аппарате значительной массы нереально. В таких условиях биплан-тандем является неплохой альтернативой. Конечно, с соответствующими ограничениями, которые для однорежимной беспилотки вполне могут быть приемлемыми.

Я _не_ утверждаю, что эта схема так уж хороша в разных применениях, просто хочу указать, что и "фе" говорить не надо торопиться.
От Сергей Зыков
К Robert (21.05.2013 23:28:45)
Дата 22.05.2013 09:00:29

у планеристов есть еще и переменное V - планер "Кашук" А. Маноцкова



картинки
http://www.reaa.ru/yabbfiles/Attachments/______024.jpg


http://www.reaa.ru/yabbfiles/Attachments/______-800.jpg


отсюда
http://www.reaa.ru/cgi-bin/yabb/YaBB.pl?action=print;num=1268500119


Журнал «Вокруг Света» / Июнь 1970 / Небо планериста
http://www.vokrugsveta.ru/print/vs/article/4377/

Шереметев Б. Н. Планеры. — M.: ДОСААФ, 1959.
http://amyat.narod.ru/theory/sheremetev_planery/index.htm
Планер «Кашук» (стр. 188)

«Кашук»: испытания планера с машущим крылом. — (Kashuk: an experiment with articulated wings. — ), Aeronautics, 1954, 31, No 4, 60, 63 (англ.)
Статья посвящена испытаниям советского планера Кашук, который представляет собой первый в мире планер с машущим крылом, практически испытанный в полете. Каждое полукрыло планера, шарнирно соединенное с центропланом, имеет рычаг, который входит в фюзеляж и соединяется там с пневматическим цилиндром. В полете набегающий поток поднимает крыло, сжимая при этом воздух в цилиндре, а затем с помощью сжатого воздуха крыло возвращается в исходное положение. Планер был испытан как с закрепленным, так и с расстопоренным крылом. При полете с расстопоренным крылом в условиях «болтанки» летчиком было отмечено почти полное отсутствие колебаний фюзеляжа по траектории.
Было установлено также, что непрерывные колебания полу-крыльев не нарушают устойчивости и управляемости, а повышают аэродинамическое качество планера. Амплитуда колебаний концов крыла, с учетом его прогиба, превышала 4 м при полном размахе 17 м.
Реферируемая статья в основном повторяет статью Б. Шереметева «Планер „Кашук"», напечатанную в журнале «Крылья Родины» No 7 за 1954 г.
А. П. Красильщиков


Kashuk: An Experiment with Articulated Wings. Tadeusz Kostia. (Skrzydlata Polska, 1954.) Aeronautics, Nov., 1954, p. 60. Descriptive design of a Russian glider with hinged wings acting against an air spring of variable rate; structural and operational data.

Kashuk: an experiment with articulated wings.

This article first appeared in the Polish magazine Skrzydlata Polska to which it was contributed by the engineer, Tadeusz Kostia. It describes a Russian glider which has been fitted with hinged wings, acting against an air spring of variable rate.

AT the International Gliding Competition held at Leszno last June, the designers of the Experimental Gliding Establishment made personal contact and established cordial relations with A Manotskov, the likeable Soviet aircraft engineer from Kiev. He is the designer of a glider with articulated wings, which has already been mentioned in wireless and press reports.
The said glider was also demonstrated in flight during the Air Force Festival held at Tushino, near Moscow, on the 20 June of this year. In connection with this machine the 3oth issue of the magazine Skrzydlata Polska (Winged Poland) contained an article by Engineer WI Nowakowski from the Experimental Gliding Establishment entitled 'New Soviet High-performance Glider with Movable Wings.' The article acquainted readers with the basic aerodynamical problems and the principles of flight of a glider of this type. Having familiarised ourselves with the theory, we will now discuss in detail the technical data and structural particulars as well as the flying test results reported in Krylya Rodiny (No 7/54), in an article entitled 'Planyor Kashuk' (The Kashuk Glider), by B Sheremetev. This glider was built in 1952 and it was named Kashuk to honour the memory of Oleg Koshevoi, a 'Young Guard' hero. It constitutes the first successful attempt in the world to enable a practical investigation to be made of the qualities in flight of this type of glider. The Kashuk is a single-seat cantilever wing, high-performance glider provided with a fuselage and controls of the conventional type. The fuselage in its construction follows that of the well-known Soviet 'A-9' glider, which was seen at the International Gliding Competition at Leszno, with its centre -section modified and with newly-designed outer portions of the wings. Compared with that of the A-9 glider, the new wing possesses a greater span and different taper and profile. These elements can perform movements in the vertical plane. The movable portions of the wings, attached by means of articulated fittings to the centre section, are fastened to two wing-fuselage spars. A special box-girder arm welded to each wing between its spars is mounted between hinges and extends to the centre section of the fuselage, where it is connected to a special pneumatic mechanism.

KASHUK
Span : 17 m (55'77 ft)
Wing area : 15'1 m1 (162'5 ft2)
Chord at fuselage : 1'4 m (4'59 ft)
Chord at wing tip : 0'35 m (1'15 ft)
Aspect ratio : 19'2 : 1
Tapering : 1 : 4'2
Wing profile: Clark YH-14
Weight in flight : 400 kg (8801b)
Wing loading : 26'5 kg/m2 (5'41b/ft2)
Efficiency with fixed wings (calculated) : 30
Counterbalancing : 26% mean atm pressure
Load coefficient : 8

The chief part of the pneumatic mechanism consists of a cylinder to whose base are attached the arms of the movable wings. The cylinder contains compressed air. The construction of the pneumatic mechanism permits the capacity of the compression chamber to vary, thanks to which it is possible to regulate in flight the frequency of the natural oscillations of the the entire flapping wing system. The change in the frequency of oscillations can take place within a wide range owing to the fact that the rate at which the working pressure increases in the cylinder depends largely upon volume.
In flight, air loads lift the wings, in consequence of which the air in the cylinder becomes compressed, and the effect of this is that the wing tends to return to its original position. This articulated attachment allows the wings to make elastic up and down oscillations under the action of random aerodynamic loads resulting from changes of direction and velocity of atmospheric currents.
The Kashuk can be flown with its wings either locked or free, and the pilot can immobilise the wing at any arbitrary moment or position.
Measurements and experimental flights have permitted an investigation into the influence of natural elastic vibrations of the wing on the aerodynamic qualities of the glider in flight in a turbulent atmosphere, and at the same time have enabled an additional examination of the structure with fixed or free wings for loads and stresses arising from the occurrence of gusts. The said glider also serves for the study of the intensity and frequency of (Continued at the foot of page 63)
60 NOVEMBER. 1954 AERONAUTICS.



■ The glider Kashuk has wings which alleviate gust loadings, and store energy gained in up-gusts for release in down gusts or in calm air. The series of drawings below indicate the way in which the system may work, although it is necessary to know the rate of the spring system and the frequency and intensity of gusts if a close analysis is to be made. The possibility that a propulsive effect may be obtained as a result of the vortex-generation by an oscillating wing is not mentioned in the article.
(See also Patents reviewed page 75)


Kashuk — continued from page 60
air gusts occurring under various meteorological conditions.
Compared with the A-9 high-performance glider, the Kashuk possesses a number of interesting qualities : launching and landing are easier. With its wings oscillating at low flight speeds, the glider sinks very steadily at a low speed of descent. With the wings fixed, control is easy and the glider possesses a sufficient degree of stability both in free flight and in tow.
Its sensitivity to deflections of the elevator is greater than that of the A-9. To make a spiral it requires a more energetic deflection of the rudder pedals which should be effected after first operating the elevator stick. As the wing has no air brakes (which we have seen on the A-9 glider), slipping should be effected whereby a descent is obtained at a speed of 2-3 m/sec.
The technique of piloting the glider in calm or turbulent air is exactly the same whether the flight is effected with a fixed or an oscillating wing.
The wing can be started in flight only in the presence of a certain minimum amount of pressure in the cylinder of the pneumatic mechanism. Tests have shown that easy stopping and starting of the wing can be obtained at working pressures in the cylinder amounting to 5-7 kg/cm2 (70-100lb/in*). This pressure is indicated on a manometer in the pilot's cabin.
Already in the first flight effected in very calm air from an altitude of 1 500 metres the pilot, J Rudnicki, noticed that the wing incessantly made small oscillating motions. If no noticeable gusts occur in the atmosphere, the motions of the wing cannot be perceived with the eye ; they can only be ascertained from the incessant deflections of the manometer needle which signals the frequency and intensity of any external atmospheric loads.
It was further found that constant oscillations of the wings in flight do not affect the glider's stability or controllability, and this applies equally to flights on a straight course and to aerobatics. The same qualities of the glider were also ascertained in high turbulence.
The pneumatic mechanism then permitted the oscillating portions of the wing to obtain full deflections extending to the structural stops top and bottom. On these occasions the amplitude of oscillations of the wing tips, including bending, exceeded 4 metres (13 ft). Diagrams made on the basis of numerous experimental flights have shown that the ' springing ' effect of the wing due to the pneumatic mechanism gives a favourable influence upon the aerodynamic characteristics of the glider.
It increases its efficiency and reduces the rate of sink at high flying speeds, which is important in obtaining high cruising speeds.
Because of this ' springing ' of the wing there is also a diminution of the stresses resulting from gusts of a turbulent atmosphere, thanks to which the pilot under these conditions does not feel the oscillations of the fuselage which occur in normal gliders in similar circumstances. To use a popular expression, this phenomenon may be compared to driving a car on a bumpy road with springs and without. Research flights have proved that, on a glider of the Kashuk type, a distinct drawing of energy from the surrounding atmosphere is apparent. Thanks to this the glider has great prospects of making record speed and distance flights. In connection with such promising prospects it is worth mentioning in conclusion that the Experimental Gliding Establishment at Aleksandrowice has recently evolved a theory and method for calculating the flight performance of gliders with movable wings. This will form a basis for the commencement of similar studies and tests in this country [that is, Poland — Editor].
The results obtained from calculation are encouraging in respect of the problem itself, as well as with regard to the further possibilities of the Jaskolka glider.
NOVEMBER, 1954 63 AERONAUTICS