Wings Forum

DaveDormer · Joined: 28 Sep 2004 Posts: 2 Location: South Africa

Jeff Le Tempt of The Dragonfly Builders and Flyers Newsletter wrote:

In my opinion the primary area where the Dragonfly will not meet the LSA requirement
(as you suggested) is the stall speed. I pretty thoroughly read the LSA public
comments and saw where the FAA refused to make special allowances for canard
equipped aircraft. I have never seen any literature that suggested the Dragonfly
had a stall speed of 45 MPH. The prototype (and all the Dragonfly literature that I
have seen) claims a stall speed of 48 MPH. I have heard of Dragonfly's that stall
at about 50 MPH. As with most aircraft as they mature they tend to get a little
more complex (and heavier). The original Dragonfly prototype did not have an
electrical system (starter or battery) and the aircraft was hand propped (originally
with a 1600cc VW). The LSA requirement is for a maximum stall speed of 52 MPH IAS
at the maximum gross weight and the most critical CG, I do not think a standard
Dragonfly would ever be able to meet these requirements. I certainly doubt that the
prototype would stall that slow (48 MPH) at its maximum take-off weight.

My Dragonfly stalls at about 62-63 MPH IAS at about 1330 pounds and the CG pretty
close to the aft limit. I think some improvement could be made with vortex
generators, but it is very important that the canard stall before the wing. I will
be installing vortex generators on my plane, but I do not think it will allow the
airplane to meet the LSA stall speed requirements. I plan on trying to develop a
modified Dragonfly that will meet the LSA requirements. This will require (in my
opinion) more span on the wing and canard. I will use my Dragonfly MK-III project
for the Dragonfly LSA project. I do not think this will be something that happens
real soon, in fact it may be over a year before I get the thing even close to
completing this project.

:Many thanks Jeff:

Sean Caranna · Joined: 11 Aug 2004 Posts: 176 Location: Daytona Beach, FL

Light-Sport Aircraft must meet the following:

● Maximum gross takeoff weight-1,320 lbs (599 kg.), 1,430 lbs. for water operation.

● Maximum stall speed-51 mph (45 knots)

● Maximum speed in level flight with maximum continuous power (Vh)-138 mph (120 knots)