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Walter A

Airfoil Used On Chris Foss Phase Lift

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Walter A

Rather than spending a few hours tweaking an airfoil from the University of Illinois website [http://m-selig.ae.illinois.edu/ads.html] does anyone know what the base airfoil for the Phase Lift is?

Thanks for helping,

Wally by Golly

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Gary B

Hi Wally,

 I'm not sure for the Phase-Lift but the Hi-Phase uses 'Eppler 193 type' in Chris's own words. The Multi-Phase also uses Eppler 193. Notes on a Centi-Phase advert I have says '10% flat bottom'.

For built-up wings he tended to flatten the underside (remove undercamber) to make building easier, I think he kept true sections for foam wings.

I have ply wing rib templates for the Phase-Lift that I could try and scan.

 Cheers

    Gary

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timboiow

I would agree with Gary The section was a 10% flat bottom with narrow flaps restoring  bit of undercamber when needed to boost things in an upward direction. If building a phase lift I ould be inclined to tweak the spar structure a little to enable more "robust" launches, and ensure the rudder cables are nice and tight  or you can get a bit if rudder flutter (guess how I found that one out !). But overall a lovely looking sailplane worthy of the building effort and in 151 span superbly elegant in flight. Look forward to seeing the pics of the build

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pete beadle

Hi Wally

The subject of wing sections has been a bone of contention for MANY years here in the UK:popcorn:

The way of getting round the arguments here was to call the section you used "Eppler 193/205 MODified" or "Clark Y flat-bottomed" and this meant you shouldn't expect an accurate or consistent section that was 100% as per the book....

Until moulded gliders arrived on the scene with their super accurate profiles, it really was pot luck in building the one you wanted to replicate on open structure and even foam cored wings.....actually, I'm a great believer in "a rose by any other name would smell as sweet" and love the fact that, back in the day, some designers/builders actually named their airfoil sections "Dunlop Green Flash" to show how inaccurate they were as well as what they looked like:)

Also, as the Phase Lift was designed to use trailing edge flaps in flight, it became a bit of a lottery as to what the section actually was, depending on where you measured it, and whether the flaps were deflected or not, as to what you were describing - and then taking the name or description with a pinch of salt;) 

Regards

Pete

BARCS1702

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Walter A

Many Thank You's - Gary, Tim, and Pete!

I am starting a Phase Lift Build for this years US Nationals Nostalgia event having acquired the plans from a BARCS member. The Al Wisher Blue Beast (in Pink) I built for last year flew very well and I was hoping for something better than the RES airplane. This is where some flaps and ailerons come in handy. I am glad the Lift was built prior to the 1980 year cutoff. I might have a chance of doing better in the standings anyway. I am always looking for platforms to build prior to the 1980 year cutoff. If you know of other sailplanes and have plans I can borrow/scan I would appreciate it.

I will post pictures as I progress. Again, Many thank yous!

Regards,

 

Wally by Golly

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Omega

Now I have a plan somewhere, I want to build one, one day, maybe with a bagged foam wing.

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