BERP rotor blades

[bootneck]

Hi everyone,

I have a few 1:144 scale Lynx HAS.1/AH.1 helicopter kits which I would like to convert to HAS.3, AH.7 and HMA.8 versions.  One of the main visual differences is the change from squared off blades to BERP blades and I would like to make a set.  Can anyone help by providing drawings with dimensions please? 

 

As can be seen in the image below, the kit rotor head and blades are quite blocky and not suitable for the later versions.

 

I am currently teaching myself to draw with CAD and I want to have a go at drawing the shapes with the intention to print them in 3D resin. Drawing up a set of BERP blades might be good practice for me.

 

cheers,

Mike

[bootneck]

Doesn't anyone have drawings or specs of BERP blades that they could share please? 

 

Mike

[Julien]

Mike, I can send you one from the Airfix 1/48 kit if it helps?

 

Julien

[bootneck]

Hi Julien,

if I cannot get a decent plan/profile with dimensions then I may need to resort to that.  I'll contact you later if it comes to it.

Thanks,

Mike

[TimB]

Hi Mike, which BERP was fitted to Lynx?  I think the later versions had BERP III.  BERP (British Experimental Rotorcraft Project) is a series of research projects.  There is quite a lot on line on the BERP IV fitted to Merlin, and IIRC the BERP III was not much different in plan view but  had a less distinct tip down turn and had fewer airfoil changes along the blade - which were hardly visible at 1:1.  There are also some plan views of the BERP III.  Exact dimensions and profiles are probably commercially sensitive.     While I do not know the chord on the Lynx BERP blades, but suspect that it will have been the same as the basic composite ones.  If you make that assumption you can probably model the blades pretty well, and at least as well as after market companies.  

 

BTW I've had a stab at the hull on the 45', and have started on the superstructure.  I'll PM you when I've done the next bit.  I'm happy to talk you through how I'm doing it - I'm learning as I go as well...

 

Regards

Tim

[bootneck]

Hi Tim,

 

I'm not sure on the blade types but I suppose it must be an earlier type, as I want to go from a Lynx HAS.2 / AH.1 to a Lynx HAS.3 / AH.7. 

If I can find out enough details about that mod. and build some HAS.3 BERP rotors, then I would like to go further in the future and do the Lynx HMA.8.  

All I have is a set of basic, straight blades of the HAS.2

 

That's good news about the 45ft FMB and, yes, I would very much like to learn the process of drawing a ships boat.  I have about six types I need to draw and build:  45ft FMB;  36ft Motor Pinnace; 35ft MSMB; 34ft FMB; 32ft Motor Cutter and 27ft Whaler.

 

I am still plodding on with Fusion 360 but I'm only progressing with verticals and horizontals, as can be seen with this weapons platform for a Westland Wessex junglie.

 

I shall need to progress on to curves, contours and the like soon though, especially if I want to be able to draw ships boats and aircraft fuselages.

 

cheers,

Mike

[wellsprop]

On 13/12/2020 at 13:55, TimB said:

Hi Mike, which BERP was fitted to Lynx?  I think the later versions had BERP III.  BERP (British Experimental Rotorcraft Project) is a series of research projects.  There is quite a lot on line on the BERP IV fitted to Merlin, and IIRC the BERP III was not much different in plan view but  had a less distinct tip down turn and had fewer airfoil changes along the blade - which were hardly visible at 1:1.  There are also some plan views of the BERP III.  Exact dimensions and profiles are probably commercially sensitive.     While I do not know the chord on the Lynx BERP blades, but suspect that it will have been the same as the basic composite ones.  If you make that assumption you can probably model the blades pretty well, and at least as well as after market companies.  

 

BTW I've had a stab at the hull on the 45', and have started on the superstructure.  I'll PM you when I've done the next bit.  I'm happy to talk you through how I'm doing it - I'm learning as I go as well...

 

Regards

Tim

 

The EH/AW101 use a rotor derived from the BERP III. They have been tested with BERP IV, but they are not used. The BERP III and IV have a different tip profile.

 

https://dspace-erf.nlr.nl/xmlui/bitstream/handle/20.500.11881/1050/2b1.pdf?sequence=1

 

The blade chord is given here - I can't comment on accuracy as I'm unsure of the commercial sensitivity of the information.

 

 

On 13/12/2020 at 14:29, bootneck said:

Hi Tim,

 

I'm not sure on the blade types but I suppose it must be an earlier type, as I want to go from a Lynx HAS.2 / AH.1 to a Lynx HAS.3 / AH.7. 

If I can find out enough details about that mod. and build some HAS.3 BERP rotors, then I would like to go further in the future and do the Lynx HMA.8.  

All I have is a set of basic, straight blades of the HAS.2

 

That's good news about the 45ft FMB and, yes, I would very much like to learn the process of drawing a ships boat.  I have about six types I need to draw and build:  45ft FMB;  36ft Motor Pinnace; 35ft MSMB; 34ft FMB; 32ft Motor Cutter and 27ft Whaler.

 

I am still plodding on with Fusion 360 but I'm only progressing with verticals and horizontals, as can be seen with this weapons platform for a Westland Wessex junglie.

 

I shall need to progress on to curves, contours and the like soon though, especially if I want to be able to draw ships boats and aircraft fuselages.

 

cheers,

Mike

 

The Lynx (and AW159) MR diameter is 42 ft (regardless of blade type). The later Lynx and all 159 use the BERP III.

 

Rotors are incredibly difficult to model and print accurately as they are so thin, there are a fair amount of papers written on the BERP blades, however, many you have to pay for.

 

http://heli-air.net/2016/02/12/case-study-the-berp-rotor/

https://www.researchgate.net/figure/Distributed-aerofoil-section-on-the-british-experimental-rotor-programme-BERP_fig34_258810454

https://www.semanticscholar.org/paper/BERP-IV-Aerodynamis%2C-performance-and-flight-Robinson-Brocklehust/8e9c0536f37a3e4f562312ad1a64d40d2c1c9adc

 

In my opinion, you would be best off modelling the blade as a (fairly generic) high-lift, flat-bottomed aerofoil at the root, a "conventional" aerofoil at mid-span and a thin symmetrical aerofoil at the tip. The aerofoil, particularly at the tip (and obviously trailing edges) is incredibly thin for a 3D printer to deal with, the printing requirements will prevent cross section from being very accurate).

 

Ben