Romualdas Bėkšta (Romas Beksta) aircraft and projects

[Retrofit]

Romas Betska RB-17:


In 1947 Romas Beksta designed the glider RB-4, a canard type glider with auxiliary 4 HP engine but the aircraft is not constructed.

In 1972 Romas started the design of a canard type airplane and at the same year he started to construct it. After two years tests on ground werezstarted: A lot of problems with the engine (a one cylinder Iz-56 motorbike engine; Usually on the homebuilt aircraft, constructers used Russian motorbikes engines). Romas made a new 2 cylinders opposite engine. During the test the airframe, propeller and the engine were modified. On October the 9th, 1977, the RB-15 aircraft made a first flight. The results of the flight weren’t good. Romas improved the aircraft and in 1979 the aircraft was totally reconstructed as RB-17. The end plates of the wing were replaced by a single fin at the back of the fuselage. Between the keel and rudder was mounted the propeller. On September the 2nd, 1979, the RB-17 aircraft made its first flight. The main wing is one spar and is made from wood. The struts of the wing are made from metal. The wing shape is TsAGI R-II-14. Forward wing have one spar and it is made from wood. Airfoil TsAGI-R-II-18. Fuselage – steel tubes covered with fabric material. Engine cowlings and fuselage top is made from duralumin sheets. The chassis struts is made from titanium tubes.
This aircraft is now on display at the Aviation Museum of Kaunas.

The main technical data (in the brackets are RB-15 data):
Wingspan:: 8,05 m (8,4 m).
Wing area: 9 m²
Canard wingspan: 3,6 m
Canard wing area: 3,6 m²
Length: 5 m (4,1 m)
Height: 2,4 m (1,95 m)
Take-off weight: 320 kg (305 kg)
Take-off speed: 60 km/h
Max speed: 110 km/h
Engine power: 25 HP.

 

[igor-mich]

RB-17 . RB-15

 

[hesham]

Great find my dear Retrofit,

and that means this designer had a series from RB-1 to RB-17 ?.

 

[Stargazer]

and that means this designer had a series from RB-1 to RB-17 ?.

Yep. Here's the RB-2 and RB-3 projects, as well as the RB-11 glider and the RB-19 lightplane:

Source: http://s385a48729ed80655.jimcontent.com/download/version/1420905828/module/9046552770/name/R.B%C4%97k%C5%A1ta.%20U%C5%BEsikr%C4%97t%C4%99s%20aviacin%C4%97mis%20bacilomis%202.pdf

 

[hesham]

Great find my dear Skyblazer,many thanks.

 

[Stargazer]

Here's a list of some online resources (mostly in Lithuanian I'm afraid...). You will also find mention of the RB-2R and RB-13 projects.

RB-11:

• http://www.vgc.lt/puslapiai/kiti-lietuviski-sklandytuvai.html?vars/action/viewArticle/nID/224

RB-17 'Antis':

• http://manosparnai.lt/e107_files/public/1285351743_228_FT0_full_page_fax_print_01.jpg

About Beksta:

• http://skrastas.lt/?data=2001-08-31&rub=1143711027&id=1146654915

Technical report by Beksta, including hypothetical canard design:

• http://s385a48729ed80655.jimcontent.com/download/version/1420905828/module/9046552770/name/R.B%C4%97k%C5%A1ta.%20U%C5%BEsikr%C4%97t%C4%99s%20aviacin%C4%97mis%20bacilomis%202.pdf

 

[Stargazer]

RB-17 'Antis' on YouTube:

https://www.youtube.com/watch?v=rRmyklwmDmc
https://www.youtube.com/watch?v=Src4hDxEldE
https://www.youtube.com/watch?v=jczcb5B5SKc

 

[hesham]

From my list,

Romas Beksta RB-7 was also a motor glider,but no more details are known.

 

[Stargazer]

The letters "RB" stand for Romualdas Bēkšta (1927-2005). In total, he designed 19 flying machines, but only 6 of them were built; the RB-1 glider, the RB-13 motorized glider, the RB-15 and RB-17 canard-types and the RB-19. Completion of the first aircraft, the RB-1, was prevented by the war. Slanderers mocked that R. Bēkšta was a new Z. Rimša, whose planes do not fly... Of course, this is an exaggerated view. Not all Lituanian designers were were as brilliant as A. Gustaitis, B. Oškinis or B. Karvelis.

In 1946 R. Bēkšta finished designing the RB-3 monoplane. His drawings were later purchased by Pranas Grinius, a glider enthusiast from Šiauliai, who completed the construction in 1957. However, Soviet security prohibited the RB-3 from being tested in the air. As a result, Mr. Grinius started to sell that plane in parts. On learning this, R. Bēkšta bought RB-3 wings, turn and height rudders, intending to use them for a new glider, for which only the fuselage would need to be made. This time, he decided not only to design, but also to build his own glider.

In 1957, Bēkšta began to design the RB-11 fuselage with a 1.5 m long centerplane supported by kicks, because the 2x3.5 m long wings were short and too small for the glider. In creating this glider, he chose the BrO-9, a type widely spread throughout the USSR, as an example, with a view to surpass its flight data. The fuselage of the RB-11 was similar from the side to that of B. Oškini's glider, but with a self-supporting structure, without overhangs, and much narrower wings, thus with lower inductive resistance.

After receiving millimeter plywood from Pransketis (Vilnius ATK aeromodeling instructor), he began to produce fuselage frames, central plane ribs and other parts on his free time from work. The work of the lone builder was easy. In the fall of 1959, the RB-11 only needed painting to be complete — yellow nitro paints, with green on the front and bottom of the gondola. After trying to roll, the landing gear locked up, and by the time the reason was identified, the flying season was over. The RB-11 tests were postponed until the spring of 1960.

The RB-11 was designed for slope flying, the glider had 8.74 m long wings of self-supporting construction, which used the NACA 4312 airfoil. The wings had main and auxiliary spars, front to main covered with 1 mm plywood, the rest with fabric. Unlike the BrO-9, the ailerons are simple, not slotted; wing area was 9.5 m2; the body/shell structure was covered with 1-mm plywood; the chassis wheel (255x110 mm) was snatched from a Yak-12.

The weight of the empty glider was 96.1 kg. The right wing weighed 11 kg, the left 10.8 kg, the centerplane - 17.9 kg, its kicks 6.6 kg, the fuselage without instruments 46.42 kg, the stabilizer - 2.5 kg, its kicks - 0.3 kg, the yaw steering wheel - 0.58 kg.

On April 3, 1960, the first flight tests of the RB-11 took place by ejecting with a rubber rope. Paulius Vaišvila was the first to fly it, followed by Julius Peleckas and others. The flights were normal, but during take-off, before leaving the ground, the glider hit the ground hard with its tail. After the fourth flight, R. Bēkšta noticed that some plywood was missing where the transition from the nacelle to the trunk tube is made, as if it had been cut out. During the repair, a smoother and stronger transition (with an additional plywood patch) was made.

In R. Bēkšta's notes, the first flights are marked as follows:
1st start 17:59 / Rudder position when crouching about +10 / Height about 2 m / Height sensitive rudder / Cross rudder less sensitive than BrO-9.
2nd start 18:04 / With a gentle turn. The landing is good / The position of the steering wheel is almost not out of neutral, the height is about 3 m.
3rd start 18:15 / Height about 20 m / Turn to the right / Landing speed about 50 km/h.
4 start / Height about 50 m / left turn / Ascent speed 70 km/h.

In the fall of 1960, R. Bēkšta started studying at the Kaunas Polytechnic Institute, and in 1961 during the spring session, the RB-11 exhibited with other students' works in Vilnius. After bringing itto Vilnius Vingis Park, he rushed to take the course exams, then he returned to Vilnius, but could no longer find the glider... That's how R. Bėkšta's only glider was lost.

The RB-11 had been developed by R. Bēkšta in order to exceed the flight data of the widely used glider BrO-9. So let's compare them. Both gliders had the same wingspan. The empty weight was almost the same (BrO-9 – 92 kg, RB-11 – 96 kg). And now for the bigger differences. The wings of the BrO-9 were supported by struts, and the flat tail beam was stiffened by struts. The wings of the RB-11 were self-supporting structures (only the centerplane is supported by kicks), and the fuselage was also a self-supporting structure (0.62 m longer than the BrO-9). The RB-11 had a significantly smaller wing area (13.95 - 9.5 = 3.95 m2) and its wingspan, which reduced inductive resistance, was larger (5.69 and 8.04) According to these indicators, the RB-11 theoretically had a lower overall resistance. However, BrO-9 had the lowest descent speed of 1.16 m/s, compared to the RB-11's — about 1.5-1.7 m/s (judging by the time spent in the air, and not from the instantaneous fixation noted in R. Bēkšta's notes). The higher descent speed was due to the significantly higher wing loading of the RB-11. As a result, the speed of landing and gliding of RB-11 was higher than the BrO-9's by 15-20 km/h. In addition, the RB-11 project did not mention wing tipping anywhere - an unanticipated reduction of the angle of attack at the wingtips. Although less important, that also increases resistance.

Thus, the too small area of the wings of the RB-11 and the excessive loading of the wings determined the poor gliding characteristics and the conclusion of J. Kavaliauskas that "it flies like an axe". Not only was it not possible to exceed the flying characteristics of the BrO-9, but the glider flew much worse. This was confirmed by J.Peleckas, who flew with both RB-11 and BrO-9.

Bronius Oškinis could not be beaten. R. Bēkšta was self-critical and did not try to praise his glider, so he behaved honorably.

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Translated from the website Lietuvos Aviacijos Istorija 1919 - 1940 m.

R.Bėkštos RB-11 - Lietuvos Aviacijos Istorija 1919 - 1940 m.

SvetainÄ Lietuvos tarpukario kariuomenÄs ir aviacijos istorijos entuziastams.

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