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Certification
Q: Will the JS1 be type certified?
A: The JS1 is designed according to CS-22
specifications. The South African type certification has been applied for and Jonker Sailplanes is
currently working through the certification flight
tests. EASA type
certification will follow. For FAA certification, South
Africa and the United States have a long-standing
Bilateral Airworthiness Agreement (BAA). The South
African Civil Aviation Authority (CAA) and the American FAA have
established communication and are collaborating per the
specifics of the BAA.
The South African CAA
has already issued its "Aircraft Design Organisation
Approval" to the Jonker Sailplanes factory. In many
ways, this is considered to be a more significant
milestone than the aircraft type certification.
Q: The JS1 is designed under CS-22 to a safety factor
of 1.725. The static test on the website appears to be
carried out at ambient temperature rather than the
normal test at 54°C
(129°F). Did you carry out a further static
load test at 54°C?
A: The JS1 is designed according to the CS-22 standard.
For the aircraft type certification Jonker Sailplanes has to prove
that all aspects of the standard are complied with. The
process for type certification will take several months.
Once the certification plan has been approved by EASA,
official tests may start, including destructive
structural tests under specific environmental
conditions.
Note that in order to obtain authorization to fly the
prototype, the South African CAA required a number of documents,
including design documents, inspections, and certain
tests. One of the tests was a structural test to the
ultimate flying loads (at ambient temperatures and
without the safety factor multiplier). This test does
not override the type certification test - the
certification tests will be done officially under
controlled conditions once the certification plan has
been approved.
Q:
What are the
limit loads for the JS1?
A: The limit loads depend on glider weight. At 360 kg
(793 lbs) the limit loads at VA are +8.0g /
-4.5g. At 600 kg (1322 lbs) the limit loads at VA
are +5.5g / -2.7g. For all glider weights the limit
loads decrease linearly from their respective VA
values to +4.0g / -1.5g at VD.
Weights
Q: What is the actual empty weight?
A: 313kg (690lbs) ready to fly.
Q: What are the max and minimum cockpit weights?
A: The min-max range is 70kg to 110kg (154lbs to 243lbs). The max cockpit weight can be
increased easily to 130kg or 287lbs (without the self-launch
installation). Extreme pilot weights can be accommodated
by special weight & balance of the glider.
Wings
Q: What is the weight of a 7.5 meter inner wing
panel?
A: Approximately 80kg (176lbs).
Q: Why are the wing panels this heavy?
A: With the thinnest wings in its class, the JS1 wings
require a lot of carbon fiber to meet the design
strength and achieve a safety factor of 1.725. The
design weight of the non-lifting parts is also set
intentionally high to accommodate a self-launch system
of 100kg (220lbs).
Q: Is it true that the airfoil is based on one of its
competitors?
A: The T12 profile is specifically designed by Johan
Bosman for the
JS1, but as is the case with the airfoils on many modern
sailplanes, similar design methods are often used in the
industry.
The profiles were verified by Johan Bosman while at Delft University, and
design assistance & confirmation were provided by Dr.
Loek Boermans.
Q: I am sure you are aware of the very bad shrinkage
that other manufacturers have with their latest models.
It is a real problem that they have yet to correct. Will
you have the same problem?
A: Jonker Sailplanes has taken measures to avoid skin
shrinkage, and hence expensive wing profiling within a
few seasons. Specifically, the carbon spar caps are
bonded wet-on-wet directly to the skins during the
initial lay-up in the molds. This eliminates a thick
structural filler (flox) bond between spar caps and the
skins, considered to be the main source of shrinkage.
The shear webs are bonded at a later stage to the
sparcaps – so all flox bonds occur between the shearweb
and spar caps. The bond area has a high safety factor
and all are post-cure inspected with a borescope. There
is also no reduction in the foam thickness near the spar
- the bending strength is not affected as with other
methods.
Q: Why does the JS1 have more wing area than some of
its 18-meter competitors?
A: The JS1 Revelation's wing is optimized for the full
range of conditions encountered in competition. Jonker
Sailplanes believes it is a given that sailplanes must
be able to run fast to hold a contest lead, but we
also believe that contests are very often won on weaker
days (as was recently demonstrated in the South African
Nationals). The JS1 wing provides outstanding climb
performance and, with its thin airfoil, also has
exceptional high speed performance. We feel that the JS1
wing has the best balance between airfoil type, wing
area, and both low and high speed characteristics.
Fuselage
Q: Is there a way for air to vent from the cockpit to
the tailboom, and from the tailboom out through the
tail?
A: The cockpit pressure releases through the tailboom
and exits at the rudder control horn covers.
Q: Does the tail ballast water tank fill from the top
or from the bottom?
A: The JS1 has two tail tanks, the standard ballast tank
(which can be dumped in flight along with the main wing
tank ballast) and an optional pilot c.g. tank to tune
the weight and balance (which cannot be dumped in
flight). Both tanks have special quick-connect fill
ports flush-mounted with the skin of the vertical
stabilizer. Unlike other gliders, this allows the standard tail tank to be
filled even after filling the main wing tanks. The
standard tail tank can also be filled via the dump
outlet behind the tailwheel if filled prior to the wing
tanks. The pilot c.g. tank can be filled or drained
independently.
Q: Is the fuselage the same as some of its
competitors?
A: As with any new design, the development of the JS1
included (1) thorough engineering review of all
published technical literature pertaining to cockpit
design for crashworthiness and (2) benchmarking of other competitive sailplanes
representative of what today's contest pilots require
and expect. Generally, the aerodynamic shapes of glider fuselages have
converged to optimum and are mostly sorted
out. The shape of the JS1 fuselage is understandably
influenced by several proven gliders and the published
literature.
The composite structure
of the JS1 cockpit owes much to the pioneering cockpit
design methods and research of several notable
sailplane designers and academics. To build upon this
and ensure the best crashworthiness, Attie Jonker and his engineering team
performed extensive materials tests, finite element
analyses, and loading to assure the structure of the JS1
fuselage meets airworthiness requirements and provides
maximum protection to the pilot.
Q: Do you expect to have more clearance for the
landing gear doors?
A: The photos of the prototype landing gear show the
doors hinged open by about 90 degrees. The gear doors on
the series production sailplanes open wider to further
increase the ground clearance.
Q: What is the size of the storage tube for the
oxygen cylinder?
A: The standard storage tube (located in the fuselage
center section behind the pilot's right elbow) accepts
an Aerox
V54GH cylinder or a
Mountain High AL-180 cylinder. A regulator with
"radial" (as opposed to "axial") outlet is recommended.
A complete MH system
(EDS O2D1-180-1P-F) with cylinder, regulator, flow
controller, service line, cannula, and face mask is
available directly from Mountain High or from Jonker
Sailplanes. For long duration or very high altitude
flights additional oxygen cylinder storage tubes are available on
a custom basis.
Trailer
Q: What trailer options are available?
A: Cobra trailers are available for the JS1 from
Spindelberger.
Contact JS for further information regarding shipping
your JS1 Revelation from the factory in a Cobra.
Q: What is the difference between the trailer for the
JS1-A and JS1-B?
A: The trailer for the JS1-A has a larger fin. The B
version glider will fit in the JS1-A trailer, but not
vice-versa.
Engine
Q: When will the sustainer be available?
A: Development of the sustainer is ongoing with several
refinements to the system such as spark ignition and
direct kerosene start.
Q: When will the self-launcher be available?
A: We are in the process of fitting the complete engine
system into a JS1 self-launch prototype. The powerplant
system is a based on the two-cylinder Solo 2645 as used in several
other production sailplanes ensuring maximum pilot
familiarity and serviceability.
Q: Any plans for electro version?
A: Not yet, but when this technology is matured, we will
definitely consider it.
General
Q: Is it possible to test fly the JS1?
A: Evaluation flights of the JS1 at our Tullahoma
location are absolutely available to pilots with
sufficient qualifications. Interested parties are also
welcome to visit Jonker Sailplanes' manufacturing facilities in Potchefstroom, South Africa
for a factory visit and evaluation flight (temporary South African
pilot certification required). Please
feel free to contact us for details.
Purchasers of JS1
sailplanes are also encouraged to
consider a Soaring Safari to visit the Jonker Sailplanes
facilities, inspect their glider, and fly their
sailplane in the southern hemisphere prior to ocean
shipment. Jonker Sailplanes is able to organize
temporary South African aircraft registration and CAA
pilot certification based on foreign licenses.
Q: What address should be used when mailing or
shipping items to
the factory?
A: Please use the post office box address when sending
by postal mail and the physical address when shipping by
courier or freight carrier:
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