Today's Message Index:
----------------------
1. 04:32 AM - Re: Nose Slam 1 & 1.5 ()
2. 11:23 AM - Re: SV: Re: KIS IT-1 Aerodynamics (Mark Kettering)
3. 03:23 PM - SV: SV: Re: KIS IT-1 Aerodynamics (Hans Christian Erstad)
4. 03:53 PM - Re: SV: Re: KIS IT-1 Aerodynamics (F. Tim Yoder)
5. 06:50 PM - TR! TO tests (tmclam@comcast.net)
6. 07:39 PM - Re: TR! TO tests (F. Tim Yoder)
7. 08:47 PM - Re: SV: SV: Re: KIS IT-1 Aerodynamics (Mark Kettering)
8. 10:08 PM - Re: SV: SV: Re: KIS IT-1 Aerodynamics (F. Tim Yoder)
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| Subject: | Re: KIS IT-1 Aerodynamics |
Hello Mark,
I was thinking that this wing would not be beginning to stall at the 80 to
65 mph short final to flair, that I think most of the reporters are
indicating. Our wings are level with a low pitch angle. I understand that it
is better to have the stall begin at the root but I thought it would be at
below 65mph for the TR-1, is this thinking wrong?
Thanks,
Tim
----- Original Message -----
From: "Mark Kettering" <mantafs@earthlink.net>
Sent: Monday, July 05, 2010 8:45 PM
Subject: Re: SV: SV: KIS-List: Re: KIS IT-1 Aerodynamics
>
> Hi Hans,
>
> That is a very interesting NACA report. I think that specific aircraft
> design had some major issues. Plus the airfoil used has a major issue of
> it's own. For example the airfoil has an initial stall angle of just 8.5
> degrees, right about where the tail starts to be less effective according
> to the report. Of course when the wing stalls then there is less down
> wash on the tail so there is less down force. But most engineers today
> think of this as a very good thing since it helps act to reduce the likely
> hood of a stall. If the main wing is starting to stall, then maybe there
> should be less down force in the tail so the plane starts to pitch down to
> keep more of the main wing from stalling.
>
> They also talk as if the tail buffeting is a bad thing. Of course tail
> flutter is but that is not at all the same as buffeting. Production
> aircraft today are required to have some sort of tail buffeting to warn of
> a stall. Planes that do not have this "stall indication" are then
> required to have stick shakers and/or stall horns. If you look at some
> production aircraft they have main wing leading edge wedges near the root
> to make buffeting prestall to meet this requirement.
>
> I am a big fan of the old NACA reports. I spent one summer at NASA
> reading a bunch of them. Many of the old reports are very applicable to
> our small aircraft. But at times you need to be very careful applying the
> information in them since at times there is a difference in goal, way of
> thinking or original conditions to what we have today. For example this
> report did not address handling qualities on any way. Yes, maybe you
> could keep the root from stalling first. But do you really want to? I
> prefer the root to stall before the center and tip since I do not like for
> the plane to roll into a spin when it stalls. Yes, you can eliminate tail
> buffeting but do you want to remove the stick shake that warns you of the
> impending stall? Some airfoils like the NACA M6 have preliminary and
> secondary stall and this can greatly effect the data but then is this data
> applicable to our airfoil?
>
> In any case, I think this supports my original theory in that all we are
> really seeing is the start of the main wing stall and it is starting at
> the root. Large radius fairings may reduce the local Cl at the root and
> then this could delay the stall at the root. But the wing will still
> stall.
>
> Thanks,
> Mark
>
>
>
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