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Old 08-15-2019, 01:23 PM   #11
rdboobier
 
Join Date: Aug 2019
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Pmdec - thanks for reply, the info you requested is :-

Dia 2676mm
Hub hole through prop 70mm
Hub flange recess 190mm

I have attempted to measure the pitch having googled it so I hope I've got it about right !

75% distance from hub centre - laid flat on the floor.
True Horizontal distance @ 90deg i.e shadow projected onto floor of blade 242mm
Trailing edge on floor - Leading edge approx 80 mm from floor (all a little difficult to be totally accurate on a carpeted floor !)

Hope this makes sence !

Regards,

Richard.
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Old 08-16-2019, 07:12 PM   #12
pmdec
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Hi Richard,

Thank you for your answer. Your measures give a 2.08 meters for the pitch (0.75 x 2.676 x pi x 80 / 242). The Chauvière data for a 2465 serial are 2.75 meters prop diameter (not far from yours) and a 1.75 meter pitch, which is very different. So, if Vickers used a system like Chauvière, the formula is different at least for the pitch.

Sorry to have not anything useful concerning your prop...

There is a simpler method to measure the pitch: have the prop on a table with flat side of the blades up. Choose a distance from the center about 2/3 of the blade length. Put a graduated regular on the blade. Measure the distance between the regular and the table each side of the blade. The difference between those two measures divided by the true length between the two points of the regular is the sinus of the angle. Any calculator will give the tangent of the same angle (tan(arcsin)), without estimating the projection of the blade width.

Regards,
PM
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Old 08-17-2019, 09:06 AM   #13
rdboobier
 
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Thanks for the reply - looks like I've got a non standard one.

I've remeasured it on the dining room table as its much firmer than the carpet !
I get similar dims but the 80 is now 85mm, not that it seems to make much difference.

Using the alternative 2/3rd method the blade width (actual) was 270mm with a rise of 98mm giving a Sine of 0.3629 -21Deg 16'
Tan of .3899 and 251mm horizontal (I think this is what you referred to ?)

However the pitch still does not (according to my calcs) fit with the French one you referred.

I've attached a couple of photos of the blade being checked on the table which show that the trailing edge is quite flat the the hub line.

Probably will remain a mystery.

Thanks again

Richard.
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Old 08-20-2019, 08:46 AM   #14
rdboobier
 
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Having spent many hours viewing both this and other sites I think the VC890 probably relates to Vickers Crayford manufacture and its diameter of 8'9".

Seems limited info on the web for Clerget 100hp engines, but I did find references to type 9J 10.7 litre 9 cyclinder built by Gwynne 100hp - however no references to planes it was fitted - especially Sopwith ones.
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