Volume 40 No 4 Aug-Sept 1989.pdf - Lakes Gliding Club

FRANK IRVING
le OSTIV
Sailplane Development Panel
(SDP) was in fOfmeftimes mainly concerned with
Airworthiness Requirements (now QS1IV Airworthiness
Standards, OSTIVAS). At Wiener
Neustadt, where we convened in the Sportschule
Lindabrunn for three days belore the OSTIV Congress,
it became clear that its interests were
much Ibroader, as the gentle reader will discem.
The aforesaid reader is, 01 course, already aware
that osnv is the intellectual branch of soaring,
OSnVAS are still used tOf certification purposes
in a tew countries who knoweth not Joint
Airworthiness Requirements ,(JAR 22, Sailplanes
and Motor Sailplanes). But the main value of the
SDP's discussions is that they actas an unofficial
forum lor JAR'. Some members of the SDP are
directly concerned with JAR, others indirectly. In
any case, what the SDP thinks today, JAR islikely
to think somewhat later, and vice versa. So, whilst
the huddled masses on the airfield! sought sheller
from the elements, the centrally heated SDP
cogitated at Lindabrunn. The account which
follows is necessarily abbreviated, but is intended
to convey the gist of the discussions. 'In parcticular
I have omitted the dull bits about
amendments being agreed subject to minor
alterations.
This produced a considerable
discussion, heavily
laden with euphemisms
After a bit of the latter by Cedric Vernon (UK)
and Jan-Eric Ollson, (Sweden), Tony Segal made
'a presentation of his full-scale crash test, as
reported in the, May issue of S&G, p130. This produced
a considerable discussion, heavily laden
with euphemisms, on the re'lative merits 015- and
6-poinl harnesses: it was agreed that one Of the
other was essential to prevent "su'bmarining", but
no 'firm preferenoe emerged.
After a statement from Manfred Reinhardt
(OSTIV president, Germany) on hOfizontal gusts,
to the effect that they were rather awkward, we
went on to consider crash loads. Alan Patching
(Australia) had produced, some recommendations
on the inertia load which the stowage of
"loose items" should withstand. The main message
is that the forward load should cOfrespond
to 209, so that batteries and barographs cannot
come adrift with lethal results. These were accepted
after the inevitable minor changes, and the
same fate belell my own recommendations on
internal pressures in fuel tanks. Alan Patching
then moved on to crash loads on engine mounts
andrueltan'ks and was rewarded with the chairmanship
01 a group to contemplate crashworthiness
in general, to report to the next meeting.
Inputs would doubtless Ibe welcome.
Inevitably, the provision of lorward towing
hooks had another airing. They are now compulsory
for flew sailplanes in Austria, Australia
and Switzerland, and generally recommended as
retrofits. Despite some confusing statistics, the
general impression was thatlorward hooksmake
for safer aerotows. Heiko friess of LBA (the German
AilWorthiness Authority) displayed a JAR 22
proposal for the definitiol"lol a "forward hook"
192
SAILPLANE
DEVELOPMENT
The OSTIV Panel cogitates on such diversities as a speaking
variometer" forward towing hooks, fatigue of sailplane
structures, improvements on gel coats, a retractable
aerotow rope and very much more.
and some relevant amendments to OSTIVAS
were agreed.
Professor Renner of Aachen University has
been gathering data ,on canopy jettisoning and
baling-out, with some input from the BGA The
SOP agreed to await his Congress paper.
The writing 01 Standards relating to the fatigue
of sailplane structures has been an on-going
topic al SDP meetings. In fact, it hasbeen going
on, mainly under the auspices of Alan Patching
and Cedric Vernon, for about 11 years. So, it was
with a great sigh of relief that they lound their
paper finally accepted - with minOfamendments.
Compact instrument panels developed for
hang gliders were demonstrated by representatlves,ot
two German and one Swiss manufacturer.
Apart from electronic barographs, also
manufactured in the WK" more comprehensive
instrumentation is now offered, with the
possibility of recording all lIight data. Airspeed
still presents some problems: the present hang
glider installation uses a little ,rotor working an
indicator via magnetic impulses, thus displaying
something like true airspeed. The development of
a "genuine" ASI is in hand. Presumably, the problem
is to find a suitable transducer, a problem
now solved fOf atmospherio pressure. One
barograph was hurled to the floor to demonstrate
its toughness, a virtue much in demand for hang
gliding. There are still some problems associated
with transducer drift and temperature compensation.
together with Ihe formalities of making printouts
acceptable to national aero clubs and the
FAt. Andre.as Deutsch (Switzerland) circulated
his ideas on specifications for both mechanical
and electronic barographs.
At BenaUa, the Board of OSTIV announced a
design, competition for a stall-warning device,
with prizes provided by the Swiss Federal Aviation
Office. The device was required to give a
reasonable warning margin regardless of Ilap
'setting, airbrake extension, bl,lgs and rain. Five of
the devices had been fitted to a Janus, 0-2480,
belonging to the German aerospace research,
organisation DLR (IOfmerly DFVlR). It is a
remarkable indication 01 the status of the German
gliding industry that the govemmenl research
organisation should operate its own Janus"
appropriately named "H'ans Zachet", supported
by a "Robin" towplane titted with a Porsche
engine and a towrope winch - and even more
remarkable that they should be flown down from
Braunschweig for the benefit of the SDP.
The systems had been evaluated by Mr Stlch
of DLR, who demwstrated them to the members
of tl1e SDP. Two of them observed something like
angle of attack whilsllhe others obseNed "bad
airflow" towards the rear part of the upper surface
of the wing 'near the root. Dick Johnson's
device consisted of a small vane which normally
trailed along the local flow and "flicked" when
subjected to reverse flow. Two of these, 01 diflerent
sizes, were fitted at about 70% chord on
each w.ing. Other devices consisted of surface
microphones detecting a certain Irequency in the
turbulence of the separated Ilow.
The angle of atlack devices were those of
Lamers/Roman, which obseNed the pressure
difference between the nose pitot and a tapping
under the front luselage, and of Wilson, which
consisted ot a small vane projecting frOfn the
canopy window.
Stopped squealing at
a rather higher speed
than it started
By the time I had a ride in the back seat, surrounded
by assorted squeaking electronic
boxes, only three of them remained seNiceable:
the Lamers/floman and both of Dick Johnson's.
They all! worked satisfactorily, in the sense that
they produced warnings at ,a few km/h above the
stall in both straight and turning flight with the
flaps ,and airbrakes in sundry positions. The
margins were adjustable, so there is not much
point lin quoting individl,lal ,figures, but 5-7kmJh
seemed typica'l. .one 01 Dick Johnson's seemed
to be 'shaded by the fuselage at Quite modest
inadvertent sideslip angles -and suffered from
some hysteresis: it stopped squealing at a rather
higher speed than it started.
Half-a-dozen turns in a mediocre thermal with
the aforesaid Johnson device switched a/') soon
convinced me thall didn't like it. Due partly to the
hysteresis, it was-squealing for more than half the
time and would have been distinctly trying after a
while. However, this was not the application originally
envisaged: the competition was a result 01
the German accident investigators pointing out
SAILPLANE &GLIDING