Bölkow Helicopter Projects

It's the Bo 70
(from Aviation Week1965 18-26)
 

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Hi,

the Bolkow-Derschmidt designed a nice commuter helicopter in
1962,which was accommodated 26-passengers.

http://www.flightglobal.com/PDFArchive/View/1962/1962%20-%200688.html?search=Bolkow%20helicopter%201962
 

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Model of Bölkow commuter helicopter with ducted propellers, Derschmidt rotor, also known as tip jet.

  • Power: two T64 engines
  • Cruise Speed: 500 km/h (270 kt)
  • Range: 1000 km (540 nm)
  • Capacity: 26 seat


Sources:
http://www.aiaa.org/tc/vstol/unbuilt/
The V/STOL Encyclopedia Series: Volume 1 Germany 16 July 2001.
 

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Bölkow Bo310 helicopter with two intermeshing Derschmidt rotors driven by turbines of 3,200 to 3,400 hp. As in the defunct Rotodyne, rotor loading is reduced by a fixed wing and two propellers are provided for forward thrust and placed at zero pitch for hovering flight.

Presented 1963 at the Paris - Le Bourget Aerosalon
  • Power: two Lycoming T55 turboshaft engines (each with 3,400 hp)
  • Rotors: two swiveling rotors, each with a diameter of 13.20 m (43.3 ft)
  • Cruise Speed: 500 km/h (270 kt)
  • Range: 700 km (380 nm)
  • Width: 22.45 m (73.7 ft)
  • Length: 18.30 m (60 ft)
  • Height:6.45 m (21.1 ft)
  • Fuselage: 2.30 m (7.5 ft) diameter
  • Maximum Take-off Weight: 10 t (22,050 lb)
  • Capacity: 24 seat

Sources:
http://www.aiaa.org/tc/vstol/unbuilt/

"Shapes and Sizes: A Technical Miscellany from Paris". Flight International. June 20, 1963. p. 967.
http://www.flightglobal.com/pdfarchive/view/1963/1963%20-%200998.html
The V/STOL Encyclopedia Series: Volume 1 Germany 16 July 2001.
 

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Any idea why the cranked rotors. I assume it's like a swept wing, reducing the relative mach speed but I wouldn't imagine it would make that much difference and it would become a much more difficult structure the way the forces would act on it.
 
It's a "Derschmidt Rotor". Hans Derschmidt filed a patent for that rotor, which was actually
flight tested in the MBB Bo 46.
The reason was, that ´with the additional hinge the advancing blade could bend back and
so reduce tip speed somewhat, allowing for greater forward speed of te helicopter.
Tests weren't really succesful, as the system proved to be overly complex and fragile.
 
Bo-120 and Bo-220 seem to be related designs. My bet is that the former may have been a two-blade version while the latter was the four-blade shown in the picture (but it's only guess work I'll admit).
 
I think you are right My dear Stargazer,


I saw old version (Bo.120) with two-blade.
 
Hi,


here is the Bolkow Bo.310 project Model.
 

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Hi,

here is a development of Bo.46 and a Bo.70 helicopter projects.

http://archive.aviationweek.com/image/spread/19650614/156/2
 

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Hi, Bolkow concept with Derschmidt High-speed Rotors: http://www.unicopter.com/1742.html
 

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From L+K 4/1965,

the Bolkow Bo.70.
 

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Hi,

here is some Bolkow/MBB Projects

German V/STOL Rotorcraft and Propellercraft
Designs of the Twentieth Century
 

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Hi,

I have in my files a two proposals for MBB,and one of them was developed from BK.117 as EC.145,but I don't
remember where is it now ?.
 
Last edited:
richard B said:
This one is a Colani "design" ("Aerodynamic Helicopter") 1977
Click to expand...

Thank you my dear Richard,and I correct and transfer it to a proper topic,but the Info in
reply # 19 was right ?!.
 
From AIAA;

Single bladed rotor transporter studied in 1955-56.
  • Rotor: 40 m (diameter) single-bladed. The rotor could then be stopped and retracted, flush with the upper fuselage surface for cruise.
  • Capacity: 30 seats
 

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Hi,

although the book Ludwig Bölkow und sein Werk. Ottobrunner Innovationen is great and
has many Projects,but it explains only a number of concepts from P.61 to P.111,but before
that and beginning of P.1 to P.60 is completely mysterious ?,any help.
 
dragon72 said:
Any idea why the cranked rotors. I assume it's like a swept wing, reducing the relative mach speed but I wouldn't imagine it would make that much difference and it would become a much more difficult structure the way the forces would act on it.
Click to expand...
Bolkow just moved the usual lead-lag hinges outboard to 1/3 of a blade span.
More conventional, fully-articulated (e.g. more than 2 rotor blades) helicopters mount their lead-lag hinges closer to the hub (e.g. Sikorsky).
MBB eventually developed a semi-rigid rotor system that has slightly flexible rotor blades made of composites. Unlike metal, composites can be tailored for different flex rates on different planes/axies.
 

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