Ron,
I=92m home from more medical tests today so here goes.
The pre-stall warning will be close gear up/down on the mono. That is flap
up/down also in a trigear. Different, but close enough.
Not to be disrespectful, but an easy reference is The Theory of Wing Sectio
ns and note how the pitch and stall angle change with a plane flap. Fowler
flap references are less available as they are company proprietary data.
Or for the hands-on guy, go get proficient in the C-172 and set the flaps t
o just shy of 30 and note how the stall indicator horn (using the same suct
ion device for a stall warning flap up and down) behaves.
The clean stall warning is remarkably close to the pre-stall warning at low
flap angles between 0-30 at slow speed approaches to the stall. At 40 deg
rees there is less of a warning as speed bleeds rapidly, but there is still
ample warning.
Note: Approach to stall testing is at a slow rate of 1 knot per second.
Rapid changes in AoA or rapid decrease of airspeed approaching the stall wi
ll affect different aircraft from plane to plane due to design differences
and rigging as well as the stall indicators design. Pilot control and tech
nique also affect the stall. We all are =93ham fists=94 on initial flights
in a new aircraft until we get proficient.
I hope I don=92t sound flippant, but It is like one of my commanders quipp
ed "you're measuring it with a micrometer, marking it with a crayon and the
n cutting it with an ax". Obsessing with small details can make you miss t
he main point which is build the aircraft per the manual. However, learnin
g should never stop, and asking questions is good, but questioning the desi
gn can lead you, me and others into making changes and decisions that perha
ps are not well thought out or even applicable.
Build and rig the plane correctly IAW the manual, then set the add on stall
indicators or devices of your choice like the book says and then test. Fl
y IAW the handbook at the speeds prescribed and the aircraft will return ho
nest feedback. Expand the flight envelope slowly. Don=92t get into the we
eds on the detail of add on systems or try to redesign things unless you pe
rsonally have calculated, and tested your change. For instance: The Europ
a POH is very good provided it is read and followed. Don't just put stall
strips on and paint over them and expect the pre-stall warning to be what y
ou desire. Tape them on, and test. Take baby steps and test three mistake
s high. Then get close to the ground. Use caution and a long runway to de
termine how these devices work near the runway pre-touchdown. Then reposit
ion and test again until the warning is acceptable to you. Some add on sta
ll strips, AoA indicators, speed warners, and lift reserve indicators and
others find omitting the stall strips and such devices is perfectly fine fo
r them and their style of flying. The latter feel these warning horns and
lights on a straight wing airplane are just annoying bells and whistles. A
mateur Experimental Aviation is a diverse group. (ATTENTION: for the sensi
tive of feelings, please disregard the following comment.) Frankly I was o
ne of the latter but to sell the aircraft I am now adding these =93bells an
d whistles=94 as the civilian market in used experimental aircraft seems to
need these. I am appalled that many of the second hand owners buy before
they have even flown the aircraft and other than the prestart checklist, ha
ve no idea what=92s in the POH or why. If a wing drops in a stall they fea
r the stall or label the aircraft is a killer, rather than noting they fail
ed to keep the ball centered i.e. coordinated flight into the stall. (ATTE
NTION: Resume reading for the sensitive pilot.)
As far as stall speeds and loading, I hope to be more clear here to you per
sonally. Because many folks arbitrarily decided a higher gross weight was
necessary using the super-factor built into the Europa design (because they
didn=92t control their empty weight), I didn=92t load my plane beyond the
1370 gross in the test phase. Hell my ID placard says 1300 still for the C
lassic, but the ops manuals (POH for my aircraft) have changed since Mod 52
and my MTOW change. Although a 1450 GW increase was the rage here in the
US 20 years ago, I completed my initial flight testing below 1370 after Mod
52. I worked up to 1450 MTOW (max takeoff weight) and kept the CG well wi
thin the limits. I personally disassembled my aircraft and inspected the a
ircraft lift points and attachments after each test session. Same with my
clients. I do not land above 1370 pounds without a post flight inspection
(over gross/hard landing checklist), as I did not drop test the aircraft t
o determine gear stresses at 1450 pounds. I personally only use 1450 as a
MTOW in smooth air and hard surfaced runways. My CG range was modified aft
er testing and my maximum G limits lowered proportionally also. My Operati
ons Limits in my aircrafts flight manual are written for my airplane and it
is flown by those operational limits I have tested. Abrupt flight maneuve
rs and turbulence were and are still avoided when flying operationally abov
e 1370 lbs. Although the Europa was built with a super-factor to allow for
amateur building, it is still a kit aircraft, with hand molded components
for the most part and there are variations we cannot predict. What we know
for everyone is: fly the plane IAW the manual and it will behave. Redesig
ning or "stretching" the limits should be avoided for the novice builder.
Not all modifications attempted by others will work exactly the same on you
r aircraft. There is always some tweaking. I try to write up my testing e
valuations or changes and provide my documentation and test results, but th
at doesn=92t mean it is going to work for you. Test and evaluate, then tes
t some more. (Frankly, that is all I ever seem to do rather than long enjo
yable cross countries as many use their aircraft for.)
Some governments around the world limit ANY change to the design or modific
ation of any aircraft without government approval. This may be nanny state
to some, but it occurs here in the US also. Case in point is the LSA mark
et. Even in the US the light sport ELSA is not really an experimental airc
raft. By regulation, its assembly cannot deviate from the factory built SL
SA without approval from the manufacturer or by contacting the FAA inspecto
r and changing its registration and airworthiness to EXPERIMENTAL EXHIBITIO
N CLASS. As many of these =93ELSA kits=94 are a less than 51% kits, the bu
ilder cannot be issued a repairman=92s certificate for these aircraft they
have built, yet they are considered Experimental Amateur Built by the FAA b
ut, are still ELSA kits and are relegated to exhibition class. It is a r
egulatory mess now as some DARs and FAA inspectors are ignorant of the actu
al wording in the regulation and intent. Now that accident information is
being evaluated closer, we shall see how it is handled or if it stays a vag
ue regulatory mess.
Probably clear as mud.
Bud Yerly
Best Regards,
Bud Yerly
-----Original Message-----
From: owner-europa-list-server@matronics.com <owner-europa-list-server@matr
onics.com> On Behalf Of rparigoris
Sent: Thursday, March 04, 2021 2:23 AM
Subject: Europa-List: Re: Stall warning airspeed for XS Mono
o:rparigor@hotmail.com>>
Hi Bud Thanks for reply. Curious, if you were to set stall warning 5 knots
above stall with flaps and gear down on a Mono XS, when approx. might you g
et warning above (perhaps below?) stall with gear and flaps up? Ron P.
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