We
did extensive before and after testing of our Legacy winglets. The results were
good. No two
experimental airplanes are identical. Airframe, engine/propeller
combinations, total weight, test weather conditions and even builder skill sets
vary from one airplane to another, therefore individual results will vary.
Nevertheless, our test results clearly indicate that, if properly installed,
significant performance improvements can be expected during takeoff, climb,
cruise, approach and landing, but particularly during cruise.
We
also collected data using our AOA. We did document that the deck angle was
lowered, unlike the testing with Lancair IV winglets. We theorized that this lowering
of deck angle is what leads to an increase in cruise speed. In any case, the
deck angle did, indeed, lower and the TAS did, indeed, increase.
We
found our best speed gain was around 14,000 feet. We started gaining airspeed
at around 9,000 feet. We conducted our tests up to 17,500, beginning at 7,500.
We
found that we have better aileron response in the low speed regime,
particularly useful in gusty landing conditions.
Stall
speed was slightly reduced. While we couldn’t measure or detect a reduction
in roll rate, the roll did seem to be “smoother”.
Most
of us builders think we will mostly use the Legacy like other airplanes, i.e.,
we will fly it at about 7 or 8,000 feet, but once we are flying, rather than
building, we soon learn that the combination of the Legacy wing, a three-bladed
prop, and big IO-500 gain a great amount of efficiency up in the teens. We gain
a significantly better (lower) fuel flow, while the TAS falls off only slightly
(unlike a spam can). I am very happy with my winglets as the teens is exactly
where they are the most helpful.
If
you plan to do a lot of traveling with your Legacy and speed and fuel burn
matter, then you should consider our winglets. We conservatively suggest a 5
knot improvement in TAS in the teens, but we achieved much better on some test
flights, and the average gain with our Legacy was more. Your mileage may vary,
of course.
Since
we manufacture and sell Legacy winglets, take all of the above with a grain of
salt! J
Happy
Building,
Ron
Jones
Legacy
Innovations
www.legacy-innovations.com
ron@leggacy-innovations.com
From: Lancair Mailing
List [mailto:lml@lancaironline.net] On Behalf Of Greg Ward
Sent: Thursday, June 04, 2009 3:23 AM
To: lml@lancaironline.net
Subject: [LML] Re: L360 winglets
I am building a
Legacy, and had the same questions. Lancair says no, matter of fact
supposedly, some people have been cutting them off of IV-P's. The guy
that is making the kits swears by them, and several people who have installed
them like them. When you install them, you also have to put in the
recessed light/strobes into the tips, another expense. We talked it over,
and did a lot of research, as most commercial and military AC have them now,
but were basically told that you had to get real high, and real fast for them
to become effective. So, for now, we will not install them as the AE's at
Lancair would surely have been offering them if they had any benefit. We
will fly in primer for a while, so have the option to install later, if somehow
it is proven that it is worth the effort and expense.
Lancair 20B N178RG in
progress
-----
Original Message -----
Sent: Wednesday, June 03,
2009 3:34 PM
Subject: [LML] L360 winglets
I am
building a L360 in Australia, and will soon have to make the decision about
what wing tips to use. The kit comes with the standard tips. However, I have
seen some Lancairs with winglets, and am wondering whether they are worth the
investment in time and money. Has anyone out there in LML land done any
research into the benefits of winglets? I am interested particularly in before
and after comparisons, both in terms of speed and general handling.
Any
info would be greatly appreciated.
Rob
Stevens
Perth,
Western Australia.