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Need Help for a propliner 404 CL_AOA

thunder100

thunder100

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62
Country
austria
dear Community

I am a newby to the forum and to FDE design

We are designing a Lockheed L-1649 Starliner
It flys not so bad,but has a bit of nasty slow speed stall caracterists.

My question

This is the CL_va AOA of the real NACA 0015 profile
See NACA 0015
It would stall at 23°

Our air File uses this (14°.jpg)

And most of the connies look like this(16°.jpg)

My questions
How do I define the correct graph ?
Why 16° and not like the FAA doc 23°?
Anybody can enlighten me how steep the graph after the stallpoint should fall?

Thanks a lot for help

Thunder100
 

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  • 16° CL.jpg
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  • NACA 0015 .jpg
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Well, the NACA graph describes the behavior of an ideal two dimensional profile at given Reynolds. The real wing is a 3 dimensional thing and uses mostly not only one kind of profile.
After this source: http://www.ae.uiuc.edu/m-selig/ads/aircraft.html the Starliner used NACA 0015 at the root and NACA 0010 at the tip.
Furthermore the stall in a wind tunnel is not the same thing as in the real world.

Therefore the graph can give you an idea how to design the alpha curve, but I think you can find the correct shape only with some flight testing.

Ciao, Sergio
 
Last edited:
Naca

dear Segio

thank you for answering

Yes we found that out in the meanwhile.Also as the FS flight model is quite simple.

Real problem is to find people which can check the Starliner realisticly rather then have an opinion(from C172's to Jets)

godspeed

Thunder100
 
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