> On Oct 15, 2017, at 9:00 AM, krnet-requ...@list.krnet.org wrote:
>
> Making the mods is just down right cheap. Then we can all practice spins in a
> KR. Makes it more attractive to a lot of people. Lets fix this.
As previously noted. A major point of this paper:
> https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19770026167.pdf
> <https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19770026167.pdf>
is that while mods can help, it is unpredictable whether a particular mod or
recovery procedure will help.
this is compounded by the fact that homebuilt airplanes vary so much between
individual airplanes of the same model.
how valid the paper is I don’t know, but I do know that they are way more
qualified on matters aerodynamic than me.
However, accumulated experience and understanding in GA design in the 40 years
since the paper was written (and 45 years since the KR design), suggest some
basic design features (mods) that can increase spin resistance and aid spin
recovery (very separate issues).
Icon Aircraft wing design was the first production aircraft to comply
completely with FAA spin resistance standards. Its t-tail gives it spin
recovery (and helps with the high center of thrust issue), but spin resistance
is more an issue of wing and fuselage design:
https://www.google.com/patents/US20140021302
<https://www.google.com/patents/US20140021302>
In Icon’s case, wing cuff with airfoil changes and wingtip, funnel airflow over
the ailerons.
I would suggest that the easiest changes for the KR would be:
Spin avoidance / resistance:
1) sight line AOA (to help keep you away from stall).
2) Stall fence between wing stub and outer panel.
3) Stall strip on inner wing stub
4) VG’s on outer 1/3 of wings.
Spin Recovery:
1) VG’s on rudder bellow stabilizer.
2) Increase rudder area below stabilizer
We will probably incorporate or test all of these mods, but won’t be flying
until summer at the earliest.
Cheers,
Owen
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