General
Questions
Kit Questions
Silent
Pure-Sailplane Questions
Fuel-Injected
Self-Launch Silent Questions
Electric
Self-Launch Questions
Silent
2 and TARGA Wing Questions
Trailer/Rigging
Questions
North America
Specific Questions
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General Questions
Q: I don't see any prices on the website?
A: Our web site caters to clients worldwide and the prices
do vary because of shipping differences (we have thus elected
to not place the prices on the website - seems to add confusion).
Just fill out the contact form for either USA/Canada or
for Europe/Other and we'll send you the current price list
immediately. The contact form requires minimal information
and your personal information is never distributed.
Q: Are there any other websites dedicated
to Silent sailplanes?
A: Alisport has one global website with multiple language
choices. We feel it makes sense for us to do this so that
the information posted is always up to date and there is
one definitive source of information. Our partner, AirEnergy,
has a separate website for the electric sailplanes (see
links) and several builders/owners have personal websites
or have created discussion groups (again, see the links
page).
Q: Are the gliders/trailers insured while
in transit to their point of delivery?
A: Yes, we insure all of our shipments and these costs are
embedded in the shipping fees. Generally speaking, the gliders
are insured until they reach the port of entry at which
point the purchaser's policy comes into effect (owner policies
generally become valid once the glider/trailer are on the
soil of the country in which the customer's personal policy
is purchased).
Q: Do you carry manufacturer's liability
insurance? I would hate to see a lawsuit impact your business
and be unable to purchase parts for my glider or obtain
future support.
A: This is a harsh reality in today's society and we absolutely
must and certainly do carry manufacturer's liability insurance
to ensure the long term viability of our company. The cost
of this is borne by every customer. However, we have made
every effort to keep the costs as low as possible by working
closely with our insurer to demonstrate stringent quality
control, document all testing, and ensure that our aircraft
have no undesirable handling traits. Additionally, we have
worked with various aviation insurance companies to ensure
that our customers are able to obtain owner insurance of
their sailplanes. If your preferred insurer is unable or
unwilling to insure your Silent glider please do not hesitate
to let us know and we will work with your insurer to remedy
any issues.
Q: Are instruments included with the kits
or the finished gliders?
A: Yes, please see the price list for included items.
Q: Is a tinted canopy available?
A: The clear canopy is standard. Tinted canopies are available
on a custom basis and can be quoted at time of order. Canopy
transparencies are produced by MecaPlexTM and
provide UV protection.
Q: Do the wing-tip wheels include a hole
or way to tie the wing down outside?
A: Yes, they have molded wheels with openings between the
spokes that can be used for occasional tie-down situations.
The composite fairings that support the wheels are not rated
for permanent tie-down. The Silents are light and easy to
dissassemble. We recommend storage in the closed trailer.
Q: Which is better, the standard instrument
panel or the large panel?
A: The standard panel weighs less (mostly due to fewer instruments),
permits easier entry into the cockpit, and does not obstruct
any vision in flight. The large panel permits more instruments.
Only the upper corners of the large panel infringe slightly
on field of view (considered by most to be a non-issue).
An "approval drawing" of your instrument panel is developed
along with your purchase agreement (ready-to-fly sailplanes
only).
Q: Which variometer should I order with
my glider?
A: Alisport offers several variometers and flight computers
when purchased with the sailplane (see the price list for
available options). Three basic variometer choices are:
1. WinterTM mechanical variometer,
Ø57mm
(Ø2
1/4")
2. IlecTM SC-7 electric variometer,
Ø80mm
(Ø3
1/8")
3. IlecTM SB-9 electric variometer,
Ø57mm
(Ø2
1/4")
For the pure sailplane without electrics, the
mechanical variometer is the recommended solution (unless
using the SB-9 which has its own 9V battery). An audio box
for the mechanical unit is available and can be added later.
It plumbs in series between the TE probe and the mechanical
vario. The SC-7 is a large instrument with an embedded smaller
vario display window. It has an Off/Mute/On switch, volume
control, 1 sec and 3 sec averager rates, digital display
for average climb/sink which also shows temperature and
percentage charge of battery. The SB-9 is a small instrument
and looks like the vario display window of the larger SC-7.
It does not have digital display features. It does have
a reserve 9V battery on the back and two averager settings.
Of the two electrical variometers, if panel space is a premium,
use the SB-9. Otherwise the additional features of the SC-7
are worth it.
Q: What is the cockpit width?
A: The cockpit is 560mm (22.0") measured across the aft
corners of the canopy ledge (inside to inside).
Q: Is the main wheel brake a drum or disc?
A: It is a cable actuated drum brake and full aft travel
of the airbrake handle activates the wheel brake. The wheel
is a standard 4 inch unit with a relatively large diameter
tire to roll smoothly.
Q: Can the high-visibility paint job be
purchased as an extra? Good idea in congested flying areas.
A: Yes, the high-visibility anti-collision paint is now
available as an option. Please see the price list.
Q: Was the Silent Club one of the original
World Class design entrants?
A: No, even though there are certainly some performance
and specification similarities between the Silent Club and
some of the World Class aircraft, the Silent Club design
constraints and goals evolved from the requirements for
Sport and Recreation Aircraft (European Ultralight). The
Silent Club and subsequent models were designed from the
outset to accept a powerplant (initially both retractable
and pod-mounted Koenig engine versions were available).
Only two prototypes of the Italian World Class design entrant,
the "Velino", were ever produced and series manufacture
was never pursued.
Q: Are any R/C scale models available of
the Silent?
A: We are not aware of anyone selling plans or producing
kits of a Silent scale model. The Italian magazine "Modellismo"
featured two beautiful scratch-built Silent R/C aircraft.
Reports are that they fly exceptionally well. See the Italian
"Articles" page of the website.
Kit Questions
Q: Could I build a self-launch Silent as
a first kit?
A: Both the pure sailplane and self-launch versions of the
Silent are easy to build. There is no fiberglass lay-up
in the traditional sense (only bonding of some pre-molded
panels). Also, difficult or critical steps are done by the
factory (wing halves are closed, fuselage halves are joined,
composite frame bonded to canopy, etc.). The manual, profusely
illustrated with over 600 photos and drawings, "walks" the
builder through each step. All parts are organized and packaged
according to the task in which they will be used.
Q: Is the self-launch Silent kit estimate
of 500 hours reasonably accurate, and would that include
paint/finish?
A: The estimate is based on double the factory time to complete
the aircraft from the kit stage. We believe it is conservative
for the basic self-launch kit and it does include paint
and finish with pneumatic surface prep tools. Extensive
profiling of the airfoil shape and surface finishing will
increase build times. Actual build times for the self-launch
Silent Club appear to be in the 300 to 400 hour range (documented
via builder logs) depending on builder experience, level
of finishing detail, and options. The Silent 2 and Silent
2 TARGA self-launchers take only slightly longer due to
a few differences such as removable winglets, tapered flaperon
hinge line, flap linkage system, and retractable gear.
Q: What epoxy and fillers will I need for
my kit?
A: A small amount of epoxy resin and fillers are required.
The materials used to build a Silent are typical for composite
construction and, should additional material be needed,
are also available from Alisport, Aircraft Spruce, Wicks,
and other aviation supply companies. The construction manual
provides information on the specific materials, surface
preparation, bonding techniques, recommended tools, etc.
Q: Are simple aerobatics (loops) permitted
in the Silent?
A: The official flight manual specifically states that aerobatics
are not permitted. The structural load ratings of the aircraft
are also published. For a kit sailplane, the "manufacturer"
is the kit builder and in theory it can therefore be certified
by the builder to any level of flight capability including
sport aerobatics (the flight test program will need to include
the relevant aerobatic maneuvers). During factory flight
testing, the Silent was subjected to loops, rolls, and inverted
flight (Silent Club only) and had no undesirable handling
traits.
Q: What tools do I need to build a Silent?
A: The following table from the extensive Construction and
Workshop Manual lists the recommended tools, equipment,
and materials:
| Electric drill
|
Indicating
torque wrench |
| Cordless
(rechargeable) drill |
Metric
Allen key set |
| Right-angle
drill (electric or cordless) |
6
mm ball Allen key (T-handle) |
| Dremel™
tool or die-grinder (with bits) |
Small
and large Phillips screwdrivers |
| Drill press |
Small
and large slotted screwdrivers |
| Ø2.0
mm (0.08”) drill bit |
Hand
rivet puller |
| Ø2.5
mm (0.10”) drill bit |
Metric
tape measure |
| Ø3
mm (0.12”) drill bit |
Metric
rule |
| Ø4
mm (0.16”) drill bit
|
Square
|
| Ø4.2
mm (0.165”) drill bit
|
Level
(digital preferred) |
| Ø5
mm (0.20”) drill bit |
30W
soldering iron |
| Ø5.5
mm (0.22”) drill bit
|
70W
soldering iron |
| Ø6
mm (0.24”) drill bit |
Electrical
crimping tool |
| Ø8
mm (0.32”) drill bit |
Multi-meter
|
| Ø18
mm (0.71”) hole saw |
Scissors
|
| Ø20
mm (0.79”) hole saw |
Shears
|
| Ø38 mm (1.50”) hole
saw
|
Swaging
tool (Nicopress™)
|
| Ø48 mm (1.88”) hole
saw
|
Cable
cutters |
| Step
drill (Unibit™)
|
Angled
long-nose pliers |
| M4
tap (optional) |
Diagonal
cutter |
| M4
die (optional) |
Flat
files |
| M5
tap |
Half-round
files |
| M6
tap |
Heat
gun |
| 90°
countersink |
Sandpaper
(various grades) |
| 7
mm wrench (x2) |
Flat
sanding blocks |
| 8
mm wrench (x2) |
Cylindrical
sanding blocks |
| 10
mm wrench (x2) |
Orbital
sander |
| 12
mm wrench (x2) |
Electric
reciprocating saw (jig-saw) |
| 13
mm wrench (x2) |
Hand
saw |
| 14
mm wrench (x2) |
Keyhole
saw |
| 17
mm wrench (x2) |
Band
saw |
| 22
mm wrench |
Paint
gun |
| 3
mm box-end wrench |
Air
compressor |
| 4
mm box-end wrench |
Threadlocker
(Loctite™)
|
| 5
mm box-end wrench |
Cyanoacrylate
glue |
| 6
mm box-end wrench |
Respirator
|
| 8
mm box-end wrench |
Leather
gloves |
| Ratchet
wrench with 10 mm socket |
Safety
glasses |
| Ratchet
wrench with 13 mm socket |
Saw
horses |
| Driver
with 7 mm socket |
Bar
clamps (Quik-Grip™)
|
| Driver
with 8 mm socket |
Locking
clamps (Vise-Grip™)
|
| Driver
with 10 mm socket |
Retaining
ring pliers |
Many of the items, such as a band-saw, orbital
sander, cordless drill, air compressor, and paint gun, are
desirable but not absolutely necessary. Some builders prefer
to borrow some of the more expensive equipment or, in the
case of painting, prefer to have their aircraft professionally
painted.
Silent Pure Sailplane Questions
Q: Can I upgrade a Silent pure-sailplane
to a self-launch Silent at a later date?
A: The Silent Club, Silent 2, and Silent 2 TARGA can easily
be upgraded to the self-launch configuration. A complete
powerplant kit is available for this transformation.
Q: I am 90 kg (200 lbs). Can I fly the Silent in the
FAI-DU Class for record attempts?
A: The FAI-DU Class dictates a flight weight of no more
than 220kg (485 lbs). The empty weight of a 12.0m Silent
Club pure glider is 135kg (298 lbs) if kept simple (minimum
instruments, no polyurethane paint, etc). This leaves 85kg
(187 lbs) for pilot and flight gear. With the introduction
of the Silent 2 and Silent 2 TARGA with their better glide
ratios, attempting FAI-DU records with a Silent Club no
longer makes a lot of sense. The 13.0 meter Silent 2 and
13.3 meter Silent 2 TARGA pure gliders have the additional
advantage of lighter carbon wings allowing slightly more
weight for the pilot and flight gear. The TARGA does have
a slightly higher weight due to the retractable landing
gear. Some additional weight savings can be attained on
a custom basis - feel free to contact us if absolute minimum
weight is required.
Fuel-Injected Self-launch Silent Questions
Q: Can I fly a self-launch Silent mostly
as a power-plane and occasionally go soaring?
A: NO! This is not what self-launchers are designed for!
Self-launchers generally spend minimal time in the power
mode and most of their lives soaring. Their engines are
used for some taxiing, predominantly for launching, and
occasionally for retrieval or ferry flights. Basically the
engine exists to provide opportunities. Opportunities to
launch on any day at any location, without a tow-plane,
when soaring conditions are less than optimum, and to venture
further from home because a ground crew is not necessary.
The powerplants in self-launchers are not intended to make
gliders into power-planes, and they are certainly not to
be used as life-savers. They are intended to be flown as
gliders first and in-flight re-starts should always be performed
with the utmost conservatism. If you need to run the engine
most of the time and prefer to shut it down only when soaring
conditions are excellent then consider a touring motorglider.
They are designed to spend most of their lives in the power
mode, unlike self-launchers.
Q: Can I run electrical instruments off
the main battery in a self-launch Silent?
A: The self-launch Silent Club, Silent 2, and Silent 2 TARGA
each have an engine battery (8Ah) that is charged via a
flywheel generator when the engine is running. We do not
recommend running instruments or avionics that draw much
current from the engine battery (basic variometers are usually
ok). Instead, we recommend the auxiliary battery tray option
for electrical instruments, radio, GPS, Palm, transponder,
etc. This way the engine battery will always be fully charged
in case the engine needs to be re-started in flight.
Q: How is the single-blade centered after
climbing to altitude?
A: The usual procedure after climbing to altitude is to
briefly run at low power to avoid shock cooling the engine.
The glider is re-trimmed after reducing power. When the
ignition/fuel-injection switch is turned off (the master
switch remains on) the propeller will windmill for a few
revolutions (quantity depends on airspeed) and it will stop
arbitrarily. At this point the blade-stop lever in the cockpit
is moved forward and a corresponding flexible plastic tab
located adjacent to the engine rotates forward into the
plane of the propeller "arc". Now it is a simple matter
of looking in the small rear-view mirror located on the
instrument panel and lightly tapping the starter button
a few times until the propeller is in the 6 o'clock position
and resting against the plastic tab. If the starter button
is held too long the blade simply overshoots, the tab flexes
out of the way, and the prop must be "bumped" all the way
around by tapping the starter button again. When the blade
is centered, the blade-stop lever is moved back and the
UP/DN rocker switch is held DN until the pylon is completely
lowered. The master switch can now be turned off. The entire
procedure is more complicated on paper than in practice.
Most pilots become adept after only 2 or 3 tries.
Q: Can you sell just the Silent self-launch
engine and propeller and if so, what is the price?
A: Unfortunately we cannot offer the Alisport engine and
pylon for use in other aircraft. It has been specifically
designed for use in the Silent self-launchers.
Q: Is oil mixed with fuel? What type of
fuel and octane rating?
A: Oil must be pre-mixed with the fuel. We recommend CastrolTM
TTS two-stroke oil (available worldwide). The engine's Electronic
Control Unit (ECU) is programmed for Europe and North America
to accommodate slightly different octane ratings. We recommend
using the highest octane alcohol-free unleaded auto-fuel
that is available. This is generally 98 RON (Research Octane
Number) in Europe and 93 PON (Pump Octane Number) in North
America (except California which is 92). Always try to use
a brand of fuel without ethanol and alcohol additives (minimal
quantities up to a few percent of these additives are ok).
Fuels with MTBE additive are acceptable. If fuel with zero
or minimum ethanol or alcohol content is not available,
then AvGas (100LL) is acceptable (may require more frequent
sparkplug changes).
Q: What is the T.B.O. for the engine and
do you produce this engine? What about spare parts?
A: The engine TBO rating is 300 hours which is conservative
for modern two-stroke engines using the latest in material
technology. The highest time engine in service has over
200 hours. The engine is assembled in-house by Alisport
using mostly stock parts that are common with the MZ engine
produced both in Italy and in Canada (CRE). The Silent powerplant
package was engineered specifically for the self-launch
application and therefore it does have a few unique and
proprietary features specific to integration with the engine
pylon (for example an external counterbalance shaft). The
fuel-injection system is comprised of mostly off-the-shelf
BoschTM components. Parts are therefore readily
available from a variety of sources. The fuel-injection
addresses the issue of carburetors leaking fuel when the
pylon is lowered into the engine bay. Not to overlook the
easier starting, elimination of mixture control, choke,
etc. Other choices for a reliable single-cylinder two-stroke
are virtually non existent (note that RotaxTM
no longer manufactures any single-cylinder engines - two
cylinders causes a domino effect and ultimately both the
glider size, weight, and cost go up).
Q: What stops the engine/propeller from
being cranked by the starter before the pylon is fully raised?
A: A limit switch detects when the pylon is in the fully
raised position and only when this happens will the starter
work. This eliminates the possibility of accidentally cranking
the engine and having the propeller impact the engine bay
doors or fuselage. The ignition/fuel-injection system can
be turned on prior to raising the pylon (i.e. fuel can circulate
before pylon is fully raised).
Q: What happens if I start the engine with
the blade stop extended?
A: The plastic blade stop flexes and sacrificially wears
as the blade contacts it (the noise will sound like a bicycle
with playing card touching the wheel spokes, only louder).
Typically, a line of smeared plastic will form on the blade's
tough polyurethane surface - at first glance it may look
like a gouge but it can easily be removed with a fingernail.
However, running the engine for extended periods with the
stop extended or at speeds above idle will damage the propeller
paint.
Q: Does the engine automatically lean the
fuel ratio as altitude changes?
A: The electronic control unit (ECU) has a built in pressure
sensor that, along with the intake air temperature, determines
density altitude. The ECU then uses its mapped parameters
and this information (along with throttle position and RPM)
to vary the injector duration and attain in the correct
fuel delivery for the given altitude. Generally speaking,
internal combustion engine power output as a function of
density altitude is as follows:
| Feet
(meters) |
Percent
Power |
| 0 |
100% |
| 1,000 (305) |
97.1% |
| 5,000 (1,525) |
86.2% |
| 10,000 (3,050) |
73.8% |
| 15,000 (4,575) |
62.9% |
Q: What is the maximum engine RPM?
A: At proper climb angle, the engine speed will be on the
order of 6000 to 6300 rpm. If the engine is over-revved
the Electronic Control Unit (ECU) will automatically limit
the maximum speed to 6400 rpm by intermittently cutting
the ignition (as would occur if the nose was lowered during
a full power climb).
Q: The published empty weight of the self-launch
Silent Club is 170 kg (375 lbs). I assume that this is without
options such as the tip-up canopy and steerable tailwheel?
A: You are correct. The published weight is that of the
basic glider without fuel. With polyurethane paint, cockpit
paint, hinged tip-up canopy, steerable tailwheel, aero-tow
nose hook, auxiliary battery, large instrument panel, radio,
headset, etc. the empty weight can easily creep up to around
190 kg (418 lbs). The self-launch Silent 2 and Silent 2
TARGA have the additional advantage of lighter carbon wings
allowing slightly more weight for the pilot and flight gear
(although the TARGA does have the additional weight of the
retractable landing gear). Regardless of the aircraft, we
strongly recommend that you take your own weight and airport
conditions (runway length, altitude, temperature) into account
when deciding on options. It is very easy to make any aircraft
heavy. The design intent of the Silent series of sailplanes
focuses on simplicity and light weight. Ask questions like,
"Are two variometers, large instrument panel, steerable
tailwheel, etc. really necessary?" More is not necessarily
better in every case.
Q: Should I install an aero-tow nose hook
on a self-launch Silent?
A: It does add some additional weight, but here are some
possible advantages:
1. Allow friends without self-launch experience
to fly your sailplane
2. Back-up plan in case of motor related problems
or extremely high density altitude conditions
3. Maintain aero-tow proficiency (can also
be interpreted as a gesture of support for your local aero-tow
operation)
4. Sailplane can be flown as a pure glider
for record attempts with the engine removed.
Q: Should I put a steerable tailwheel on
my self-launch Silent?
A: Before answering your question, we should point out that
a fixed tailwheel is standard equipment on the pure sailplanes.
The fuel-injected self-launch Silent Club, Silent 2, and
Silent 2 TARGA sailplanes come standard with steerable tailwheels
and wingtip wheels. A steerable tailwheel does not make
much sense for the un-powered versions of the Silent or
for the electric self-launch Silent Club.
Q: In some of the photos it looks like the
self-launch Silent Club is on the nose wheel when occupied
by the pilot. It seems that this would negate the use of
the steerable tailwheel - so how does this work?
A: The glider remains in the tail-down position with a pilot
on board. The glider only pitches onto the nose wheel when
substantial power is applied (in other words, the thrust
is applied at a point above the CG and creates the nose-down
pitching moment). This is the condition visible in the photos.
For taxiing, the glider remains in the tail-low position.
If an obstruction is encountered (ex. main wheel in a rut)
then full power can be applied to move the glider forward
(the tail will obviously lift, until power is reduced after
clearing the rut). The nose-wheel provides several advantages
for the Silent Club:
1. Allows for a static full-power test prior
to taking the active runway. This is not always feasible
with many self-launchers.
2. Permits full-power to be developed prior
to releasing the brake and beginning the take-off roll.
Many self-launchers (including the Silent 2 and Silent 2
TARGA) are obligated to increase power gradually and thus
the pilot must verify maximum engine rpm before liftoff.
3. The main wheel is located further aft (located
closer to the cg). This results in better ground handling,
less chance of "ballooning" when the main-wheel first contacts
the runway, and less effort when lifting the tail to install
the tail dolly.
Q: What is the L/D of a self-launch Silent
with the pylon extended?
A: Most self-launchers with an extended pylon and stationary
propeller experience a sink rate from 2 to 3 times worse
than the corresponding clean sailplane. For example, the
self-launch Silent Club at 83 km/h (45 knots) with the pylon
extended and the propeller at the 12 o'clock position has
a sink rate of approximately 1.8 m/s (350 fpm) yielding
a corresponding L/D of 13:1. For comparison, the same sink
rate can be obtained with approximately 1/4 air-brake extension.
The sink rate is similar for the Silent 2 and Silent 2 TARGA.
It is important to note that the power-on climb-rate is
at least 35% higher than the sink rate. A "dirty" glider
can therefore glide back to the airport in a worst case
scenario, assuming sufficient altitude has been attained
to turn around. This does not take into account the typical
advantages of climb-out into the wind and return glide with
a tailwind. With the propeller positioned at the 6 o'clock
position (ready for retraction), the sink rate is lower
and the L/D greater, but this is not representative of the
worst case scenario.
Electric Self-Launch Silent Questions
Q: Are the electric self-launch Silent sailplanes
available as kits?
A: The electric self-launch Silent sailplanes are presently
only available in ready-to-fly form. There are no plans
at present to develop kits. Let us know if you are interested!
Q: What is the max altitude under power
to battery depletion for the electric self-launch Silent?
A: With the standard batteries the electric self-launch
Silent Club can climb to approximately 2000m (6600ft) on
a charge. Most pilots will climb to a lesser altitude and
shut it down in the first thermal, retaining the remainder
of the charge for a save. Re-charge times are rapid and
depend on the available outlet voltage (not the batteries).
The Silent electric powerplant was initially developed for
gliderports in Europe that have noise restrictions and are
only allowed to winch launch. The electric Silents effectively
circumvent these restrictions. The electric Silents represent
the best solution based on available technology and cost.
The Silent Club was the world's first series production
electric self-launcher and is the world's only viable electric
light sailplane.
Q: What is the lifespan of the batteries?
Run time per flight?
A: The life of the batteries is measured in cycles as opposed
to years and they are rated for 500 full cycles. One launch
a week equates to approximately 10 years. Regarding the
duration, if in full power climb, a full charge will last
about 20 minutes whereas in cruise they will last about
one hour.
Q: What is the propeller diameter of the
electric self-launch Silent?
A: The propeller is a two-blade folding design (folding
motion is in the plane of the propeller disc) and the blades
swing outward by centrifugal force. Propeller diameter is
1.92 m (75.6").
Q: Max RPM?
A: The maximum electric motor speed is 4000rpm. Best climb
performance is at 3400rpm. With a belt reduction of 25:64
(1:2.56) the propeller speed during climb is approximately
1300rpm.
Q: Empty Weight (with batteries)?
A: The empty weight with batteries is typically 200 to 208kg
(440 to 458lbs) depending on instruments and accessories.
Q: Electric Silent ground roll on paved
surface?
A: Takeoff distance is conservatively published as being
less than 200m (650 ft) to be on the safe side even for
unprepared grass fields. However, the electric Silents have
demonstrated take-off distances in the low 100 meter range
with zero wind conditions.
Q: Electric Silent rate of climb?
A: Rate of climb is published as being greater than 2.0
m/sec or 390 fpm (the actual climb rate is generally on
the order of 2.5 m/sec or 500 fpm). Additionally, the electric
motor output is not degraded by increasing density altitude.
Q: Weight, Number and Type of batteries
(Volts/Amps/Watts)?
A: There are 12 battery packs (72VDC, 230A) wired in parallel
with a combined weight of approximately 42kg (92lbs).
Q: Silent electric motor type and specifications?
The electric Silents use an AirEnergy permanent magnet motor
that is de-rated to 13kW (it can be taken to 16kW continuous
power). It has replaceable brushes and weighs 8.5kg (18.7lbs).
The brushes can be inspected without loosening or removing
the belt drive.
Q: What type of charger do you use, and
how long does it take to charge a flat pack? If you are
not using a Delta Peak Detection charger, my question is
why not?
A: Recharge time varies with available supply voltage. Using
220VAC, charge time is approximately 45 minutes (using 380VAC,
25 minutes). Three cables connect the charger to the sailplane:
(1) a common negative connector, (2) a twelve-pin positive
connector (one pin per battery), and (3) a twelve-pin temperature
connector (one temperature probe per battery). The batteries
are charged with a constant current system with a proprietary
AirEnergy voltage detection algorithm that far supercedes
the delta peak detection system (we cannot go into more
detail about it). Other chargers will not work with the
glider.
Q: What cockpit instrumentation and controls
do the electric Silents have for the motor?
A: The power controls comprise a key switch, master switch,
throttle, main fuse, and LCD display. All of the controls
are designed for left hand operation, so the right hand
remains at the stick. The following summarize the shut-down
and start-up procedures:
Shut-Down Sequence
1. Pull back the power lever (linear precision
potentiometer on the left side)
2. Turn off the motor control (toggle switch
in the instrument panel)
3. Turn off main fuse (on the right side at
the "three-lever retraction control unit" TLRCU)
The left hand has moved from the left side
(power lever), to the toggle switch on the instrument panel,
and is now across the chest at the TLRCU on the right side
of the cockpit near the canopy frame.
4. Activate the motor brake (lever "1" at the
TLRCU pulls a disk brake and stops the windmilling propeller,
this can be observed in the rear-view mirror)
5. Activate prop positioner (lever "2" at the
TLRCU releases the brake and extends the indexing stop against
which the blades now turn by wind force until they are hanging
down parallel, again the mirror shows what is happening
6. Retract unit (lever "3" at the TLRCU actuates
the electric actuator that retracts the prop unit)
The entire procedure takes about ten seconds
and is quite intuitive. For example, once the motor has
been turned off and the propeller blades are still windmilling,
one instinctively expects a brake (lever 1), and if the
blades are not folded correctly and are out of position,
the pilot logically looks for a means to bring them into
the 6 o'clock position (lever 2), and then the pylon obviously
has to be retracted (lever 3).
Start-Up Sequence
1. Extract unit (lever "3" at the TLRCU actuates
the electric actuator that raises the pylon)
2. De-activate prop positioner (lever "2" at
the TLRCU activated the brake and retracts the indexing
stop, the propeller unfolds)
3. Release the motor brake (lever "1" at the
TLRCU releases the disk-brake and the propeller starts windmilling,
mechanically the motor is now ready to be turned on)
4. Turn on main fuse (on the right side at
the TLRCU)
5. Turn on the motor control (toggle switch
in the instrument panel)
6. Push forward the power lever (linear precision
potentiometer on the left side)
Now the left hand has moved from the right
side (TLRCU) via the instrument panel to the left side (power
lever). This procedure also takes about ten seconds.
Q: Is pylon Extracted/Retracted using the
motor batteries?
A: The electric Silent pylon is raised using the engine
batteries driving an electric ball-screw linear actuator.
The electric actuator will retract the pylon, however it
is perfectly feasible to allow gravity assisted retraction
without using any battery power (linear actuator simply
back-drives).
Silent 2 and TARGA Wing Questions
Q: Why should I consider a Silent Club since
the Silent 2 and Silent 2 TARGA have a much better glide
ratio?
A: The 12.0m Silent Club wing has delightful handling, excellent
climb performance, very acceptable glide performance, docile
stall, and is cost effective due to the fiberglass construction
and relatively simple planform shape. We know of many Silent
owners that would still select the 12.0m wing today because
it meets both their flying needs and budget. The biggest
advantage of the 13.0m Silent 2 and 13.3m Silent 2 TARGA
wings is a substantial increase in glide ratio allowing
for excellent cross-country performance. Saying that one
is "better" than the other does not apply to all pilots
equally. Compare and weigh the qualities that you consider
important.
Q: What are the structural differences between
the longer wings and the 12.0m wing?
A: The 13.0m and 13.3m wings have pultruded carbon-fiber
spar caps whereas the 12.0m wing has unidirectional fiberglass
spar caps. Both wing types use synthetic core sandwich structures
that are vacuum bagged and heat cured, but the skins on
the Silent 2 and TARGA wings include carbon fiber while
the Silent Club wings are entirely fiberglass. All wing
types have carbon fiber flaperons dictated by stiffness
requirements.
Q: What are the load factors of the Silent
2 and Silent 2 TARGA wings?
A: The maneuvering loads are +4.6g/-2.65g (based on a gross
weight of 300kg). The ultimate (limit) loads use the JAR
safety factor of 1.50 plus an additional factor of 1.15
to account for hand lay-up of the fabrics. The wings have
been statically tested to beyond +8.0g.
Q: Is wing flutter analysis and testing
really necessary for light sailplanes?
A: We believe that light aircraft still need complete engineering
analysis and testing. This professional and long term approach
requires significant investment in computational software,
skilled personnel, and testing time. The Silent 2 also underwent
complete ground and in-flight aeroelastic testing to ensure
that there were no flutter tendencies.
Q: Does your Construction and Workshop Manual have detailed
information on the 13.0m and 13.3m wings like it does for
the 12.0m wing?
A: Absolutely! The same type of profusely illustrated and
detailed technical information is included the Construction
and Workshop Manual for the Silent 2 and Silent 2 TARGA.
This is certainly a requirement for those owners building
a kit. Owners of factory-built aircraft find the manual
extremely beneficial too and continue to comment on the
quality, detail, and usefulness of the technical information
(in addition to the Flight and Maintenance Manual).
Q: Can I use the standard 12.0m trailer
for the performance 13m wing?
A: Yes, the existing trailer can be used. Holders for the
removable winglets will need to be added. Trailers ordered
with the 13.0m Silent 2 or 13.3m Silent 2 TARGA sailplanes
are longer than the Silent Club trailer.
Q: Is a larger engine needed for the Silent
2 or Silent 2 TARGA?
A: No, our overall design focus is still the same. Keep
the glider light and the costs for self-launch independence
within reason. Even with a longer span, the weight of the
13.0m and 13.3m wings is slightly less than the 12.0m wing
and the aerodynamic efficiency is higher, so the power-on
climb rate is slightly better. Self-launchers manufactured
from late 2003 onward use the A302efi engine which has the
same displacement and power output as the earlier A300efi
engine.
Q: Are you developing a retractable gear
version of the Silent 2?
A: The Silent 2 is a sailplane served well by fixed landing
gear. However, we do listen to what our customers prefer,
hence the development of the Silent 2 TARGA with its retractable
landing gear and variable-incidence stabilizer. An optional
retract upgrade kit is available for the Silent 2.
Trailer/Rigging Questions
Q: One-man rigging and wing panel weight?
A: The Silent lends itself very well to single-person rigging.
However, each wing panel cannot be lifted by one person,
so a "one-person rig" is required. One-person wing assembly
rigs are available - please see our price list. Wing panel
weight for the 12.0m wing is on the order of 39.5 to 40.0kg
(87 to 88lbs) and approximately 2/3's of that is at the
root. The 13.0m and 13.3m wing panels are approximately
4kg (10lbs) lighter than the 12.0m panels due to extensive
use of carbon fiber.
Q: Who makes the clamshell trailers?
A: The trailer manufacturer is AvionicTM of Poland
- same manufacturer as for the PW-5 and other East European
ships. Running gear is all Alko-KoberTM (like
on many of the German trailers), but the clamshell and chassis
are simpler, hence the price difference.
Q: I'd like to keep the Silent Club glider
trailer in my two-car garage. What are the trailer dimensions?
A: The length of the Silent Club trailer "box" is 6600mm
(259.9") and the tongue is 900mm (35.4"). This gives an
overall length of 7500mm (295.3"). When level, the height
of the fin is 2200mm (86.6"), the height of the front edge
of the box is 1700mm (66.9"), and the top of the ball is
400mm (15.8") off the ground. The maximum width is 1700mm
(66.9") at the wheels. Tire size is 165 R13. The trailers
for the Silent 2 and Silent 2 TARGA are slightly longer.
See the trailer pages of the website for additional information.
Q: Do the trailers have a jack on the tongue,
a hand brake, a surge brake?
A: Yes, they have a jack with a caster wheel. They also
have a parking brake and surge brakes.
Q: Are the trailers available with an aluminum
top?
A: We do not offer a standard trailer with an aluminum top.
However, an aluminum top is available via special request
from our trailer supplier (additional cost item). Glider
delivery time requirements may be impacted.
Q: Are the wing trolleys held captive so
that they do not tip over?
A: Yes, there is an aluminum channel running the length
of the trailer sidewalls that holds the trolley captive.
Q: I saw a non-clamshell trailer in KitplanesTM
- is it still available?
A: The closed trailer is a previous version produced by
Umbra of Italy. With exception to not being a clamshell,
it was generally considered to be an excellent trailer,
but not as cost effective as the Avionic. It is no longer
offered.
Q: What holds the wheeled wing dolly to
the tapered end of the Silent Club wing?
A: The ground handling wing dolly (saddle) fits the 12.0m
wingtip in a glove-like manner. The dolly has minimal tendency
to come off and is very safe for most ground maneuvering.
Note that, the ground handling wing dolley for the 13.0m
Silent 2 and 13.3m Silent 2 TARGA clamps to the wing since
it cannot slide onto the wingtip.
North America Specific Questions
Q: Does the Silent have a race handicap?
A: Yes, all versions of the Silent are listed in the contest
handicap spreadsheets maintained by the SSA. The handicap
for the Silent Club pure glider is 1.21 and the handicap
for both the fuel-injected and electric Silent Club self-launchers
is 1.18. The values for the Silent 2 are 1.17 and 1.15 for
the pure glider and self-launchers, respectively. Silent
2 TARGA handicap values are pending.
Q: Do you have any self-launch Silents in
stock here in the US? The reason I ask is that I can't get
financing until the glider is on US soil.
A: We try to keep at least one kit available for immediate
pick-up, but there are times that we are without one on
hand. For ready-to-fly gliders the deposit can be paid and
then financing finalized the moment the glider arrives in
port.
Q: Can the deposit be put into a third person
(bank) escrow account in case the aircraft is not delivered
within a reasonable agreed upon time. I got burned to the
tune of $10,000 on an aircraft purchase refundable deposit
when the builder went bankrupt.
A: Very valid and understandable concern. We know of one
self-launch Silent owner who, |