Propeller model

[Vijayakrishnan Kuttinath]

While building propeller with OpenVSP, the twist of the outer end of the propeller blade modellled with respect to the twist at the innermost part of the propeller blade. The absolute value of the propeller twist is not maintained. Is there any way one can 'fix' the reference for the propeller twist sections. In my case, while I have a 10 degree twist at the outer section, in the model the absolute twist is 0 deg. But the relative twist between sections is maintained. I request members familiar with this kind of issue to kindly advice.
With regards

[Cibin Joseph]

VK,

I assume you are working with the 'Prop' model in OpenVSP.

Propeller pitch angles are usually referred to with respect to 3/4 blade radius. This value (generally denoted beta_3/4) may be input under the 'Design' section. 

If the twist distribution is provided under the 'Blade' section, the blade is rotated about the blade pitch axis so that beta_3/4 is maintained.

For eg, if the twist dist specified is:

0.10R => 40 deg

0.75R => 30 deg

1.00R => 10 deg

then, an input of beta_3/4 = 0 deg would rotate the blade such that the geometric pitch angles are now:

0.10R => 40 deg-30 deg = 10 deg

0.75R => 30 deg-30 deg = 0 deg

1.00R => 10 deg-30 deg = -20 deg

Check if beta_3/4 is correctly input in your case.

[Vijayakrishnan Kuttinath]

Thanks for the detailed explanation, Cibin.  My beta input in 'design' section was different from what I wanted. Corrected it now.

[Rob McDonald]

You can also disable this feature and switch from beta34 to feather mode on the design tab. Then it is a pure geometric addition. 

Rob

On Wed, Nov 13, 2019, 1:30 AM Vijayakrishnan Kuttinath <vijayak...@gmail.com> wrote:

Thanks for the detailed explanation, Cibin.  My beta input in 'design' section was different from what I wanted. Corrected it now.

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[Vijayakrishnan Kuttinath]

I did need to specify the beta3/4 for CFD calcs. Thank you Rob for the info.
Regards,
vijayakrishnan K

On Wednesday, 13 November 2019 20:54:30 UTC+5:30, Rob McDonald wrote:

You can also disable this feature and switch from beta34 to feather mode on the design tab. Then it is a pure geometric addition. 

Rob

On Wed, Nov 13, 2019, 1:30 AM Vijayakrishnan Kuttinath <vijayak...@gmail.com> wrote:

Thanks for the detailed explanation, Cibin.  My beta input in 'design' section was different from what I wanted. Corrected it now.

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