I have a model airplane that has about 10 degrees of forward sweep. Flies normally. However the wing is extremely stiff and will still flutter at high speed (150mph) if the ailerons have any slop in them.
On 7/12/10, zorc...@aol.com <zorc...@aol.com> wrote: > Then I guess every Mooney out there must be terribly unstable.... > > Bill Zorc > Vero Beach, FL > RV-8 N2046F > > > > > In a message dated 7/12/2010 12:45:27 P.M. Eastern Daylight Time, > aerona...@sbcglobal.net writes: > > On a more basic note, I will add two things about forward sweep. > 1. Your wings must be much stronger to handle the forces caused by the > negative stability. > 2. It generally requires a computer controlled flight system to handle the > bending moments. > Not recommended. > Hal Dantone > > --- On Mon, 7/12/10, Mark Langford <n5...@hiwaay.net> wrote: > > From: Mark Langford <n5...@hiwaay.net> > Subject: Re: KR> forward sweep > To: "KRnet" <kr...@mylist.net> > Date: Monday, July 12, 2010, 2:38 PM > > I don't remember the exact reason, but I read in a Raymer aircraft design > book that any kind of forward sweep was a bad idea on general aviation > aircraft, for various reasons including stability and stall > characteristics. > We're talking forward sweep though, not just "no" sweep. > > Below is something I snagged off the web: > > Advantages > > a.. Better off-design span loading (but with less taper: Cl advantage, > weight penalty) > > b.. Aeroelastically enhanced maneuverability > > c.. Smaller basic lift distribution > > d.. Reduced leading edge sweep for given structural sweep > > e.. Increased trailing edge sweep for given structural sweep - lower CDc > > f.. Unobstructed cabin > > g.. Easy gear placement > > h.. Good for turboprop placement > > i.. Laminar flow advantages? > > > Disadvantages > > a.. Aeroelastic divergence or penalty to avoid it > > b.. Lower |Cl?| (effective dihedral) > > c.. Lower Cn? (yaw stability) > > d.. Bad for winglets > > e.. Stall location (more difficult) > > f.. Large Cm0 with flaps > > g.. Reduced pitch stability due to additional lift and fuse interference > > h.. Smaller tail length??? > > Mark Langford > n5...@hiwaay.net > website www.n56ml.com > > > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html > _______________________________________ > Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp > to UNsubscribe from KRnet, send a message to krnet-le...@mylist.net > please see other KRnet info at http://www.krnet.org/info.html >
