Clive,
In developing the LSA version I did go to Vortex Generators to lower the
stall speed. We had them made up for the curve of the Europa wing.
Clean stall speed was reduced about 6 knots from 50 KCAS to 44 KCAS.
Touchdown speeds can be as low as 45 KCAS with the stall at about 40.
Aileron control is much improved down to 40 KCAS with 27 degree flap.
The problem with VGs or Slats is you will drag the tail before you stall
the Europa in ground effect clean, and I have even drug the tail with
full flaps.
With the VGs I am very comfortable at 55 KIAS on final fully loaded, and
50 KIAS solo lightly loaded, and once in ground effect, pull the power
back, and hold it off until 45. The flaps can be lowered with the VGs
slightly more, but since you will be nearly dragging the tail before
getting the benefit of the increased flap angle, I just don't see the
advantage. Lowering the approach to 45 KIAS power on is possible, and a
flare out is possible, but watch the sink rate.
On approach, the airspeed must be watched closely. The ailerons and
feel of the aircraft is so sound you can find yourself at 40 KIAS in
perfect control, but in a horrendous sink rate. (Falling with style.)
On asphalt, due to the residual thrust of the WD, Sensenich, or
Airmaster Propellers in the flare, the landing roll of my Classic just
didn't decrease significantly. Maybe 75 feet shorter. Takeoff
performance was not improved over the mono distances unless a yank it
off at 45 KIAS takeoff was planned. With a full turbo, Airmaster 332,
and lightly loaded, 400 feet was possible. Although the plane with full
power will fly at 45, with a stall margin at full flaps, if the engine
coughs, you are at a very high deck angle and climb angle. If the
engine fails, as in any aircraft, even the 750, you must push over
aggressively, and expect significant impact forces and damage if engine
failure occurs at best angle.
In testing the Zenith 701, it was worse than what I experienced in the
Europa LSA. The plane is very light and has more wing area and
consequently it pops off the ground quickly, but has no glide ability.
Engine failure on takeoff on a short field has a significant risk
factor. A scary exercise in the Zenith 701/750 is to approach the
runway at idle power and min approach speed of 35 - 40 KIAS and try to
flare out without adding power. Without a power increase, the nose gear
will not survive normally... The 701 does not have sufficient tail
volume to flare at these speeds. The 750 tail area was increased as was
done in the 801. In the 701, I and the aircraft survived because I kept
my speed at 35 and abruptly flared to allow the momentum to raise the
nose enough for a main gear smack down. This characteristic of
insufficient tail volume is evident at Sun 'n Fun as there is usually a
Zenith 7 something with a smashed front end due to a landing mishap for
sale in the "Parts Mart". If you wish to flare out on an engine out
approach in a slatted or VG equipped aircraft, stick to your glide speed
that allows a flare out.
The Europa is just not comfortable getting off in less than 600 feet,
off grass, no wind and climb over a 50 foot tree line. You can't see
the trees due to the deck angle. The VGs allow impressive climb angles,
but without margin for error. The deck angle on a short field, over
obstacle, takeoff to climb at 45 KIAS is quite impressive and control is
comfortable. On landing, the VGs give excellent control on final, but
keep power at the ready if a downdraft is encountered as your stall
margin is reduced. Keep the nose up and with a firm contact, hold the
nose off, and landing rolls can be quite short. But not less than 500
feet as it still wants to float a bit. I did not have the opportunity
to do any over 50 foot obstacle landing rolls. The nose is high, the
landing area is not in sight and if you lower the nose, speed picks up
quickly.
100 meter operations with two on board are not very comfortable in any
aircraft. There are insufficient margins in my opinion.
Troy at Just Aircraft has slatted his aircraft and calls it a Super
STOL. It is impressive, but again is very light, power dependent, is
terribly slow, but fun. Its landing gear have large oleos and are
designed for very rough terrain. You are near the margin on takeoff,
and power on is recommended for landings at min speeds. The Super STOL
is a much tougher and more capable aircraft for STOL operations than the
Zenith but not as roomy as the 750.
Just my opinion.
Regards,
Bud Yerly
----- Original Message -----
From: Clive Sutton<mailto:clive.maf@googlemail.com>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Friday, September 12, 2014 2:15 PM
Subject: Europa-List: Re: STOL enhancement?
<clive.maf@googlemail.com<mailto:clive.maf@googlemail.com>>
Thanks for everyone's responses. The fact is that some STOL users may
choose a CH750 over a Europa and for that reason it is worth considering
improved STOL performance in my view. A consultation with AD at the LAA
revealed that 33 degree flap was tried during development - which
improved stall speed, but aileron authority was degraded at that speed.
So I may try a phased approach to improve STOL (1) vortex generators
ahead of ailerons coupled with an increased flap angle (2) fixed
position leading edge slats (3) deployable leading edge slats that come
out with flaps.
If Europa landing performance could be reduced to below 100m, shorter
fields may open up the possibility of more people using their own land
and thereby the Europa regaining/retaining its appeal. Available
airfields (at least in the UK) if not now, then in the future, are
becoming a limiting factor . . .
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=430439#430439<http://forums
.matronics.com/viewtopic.php?p=430439#430439>
http://www.matronics.com/Navigator?Europa-List<http://www.matronics.com/N
avigator?Europa-List>
http://www.matronics.com/contribution<http://www.matronics.com/contributi
on>
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