VGs on blunt fuselage

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Georden

Well-Known Member
Joined
Sep 17, 2006
Messages
154
Location
Calgary, AB Canada
Looking for some test results of vortex generators on the aft portion of a blunt fuselage.

The aircraft I'm thinking of is an osprey II where the back of the canopy is pretty much shaped like 1/4 of a sphere. Lengthening it isn't an option due to prop placement. The only photos of VGs on the canopy of an osprey I have found look to be installed too far aft and buried in the boundary layer making them ineffective. Looking to reduce drag and get cleaner flow into the prop.
 

clanon

Well-Known Member
Joined
Jun 6, 2007
Messages
1,103
IMHO it's usually trial and error (around ballpark) and trying to get the flow attached in the different angles...
Maybe you could do some smoke tests ...
PS:the Cessna 337 SkyMaster seems to use'em in that way...
337-7 copy.jpg

i'll check Hoerner books later...
 

Aircar

Banned
Joined
Feb 20, 2010
Messages
3,567
Location
Melbourne Australia
Probably checking under 'vortex generators' per se will pull up more examples --they have been used for decades on lots of aircraft but only 'discovered' by homebuilding about fifteen years ago --the Armstrong Whitworth Argosy was a good example of a very low fineness ratio body that has prominent Vgs at the rear of the upper fuselage bulge (cockpit ) and the aft nacelle -- used to get rides on them to Tasmania regularly in the jump seat and lived next to three doing turnarounds 4 x 2000 HP twin boom giant . Many military aircraft show then all over --the Israeli Arava is another rather blunt body with Vgs --with a rear propeller the flow tends to want to head for the low pressure region of the prop blade under power and hence separate prematurely --the C337 uses a cooling fan to overcome this but with power off to the rear engine is subject to lots of separation --the glass goose and the De Vore Sunbird both needed VGs and several other amphibs have used then since becuse of the expanding intersection in that area.
 
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