Hop in your trike for an early morning or evening
flight, and the workaday world takes on a whole
new perspective. That’s what flying can do for
you…and you won’t get a better view than from
a trike. Just remember, steering these weightshift
machines isn’t like a three-axis aircraft.
Instead, you’ll push right to steer left; envision
the angle of the wing.
This rear-view of the XT 912 highlights the simplicity
of the trike’s design. The propeller is the
Australian-built Bolly carbon-fiber propeller.
The aerodynamic fins on the wheel pants aren’t
just for decoration; they aid directional steering
on the ground.
AirBorne’s XT 912 was designed around the 80-hp
Rotax 912 engine. The chassis was completely
redesigned to withstand the added thrust from this
powerful engine.
Disassembled, the back of the trike’s seat folds
down to align with the top of the engine to facilitate
transport and storage. The wing’s king post
mounts into the solid steel bracket folded back
upon the fuel tanks. A gas strut assists the pilot
in raising the trike wing into position.
Terri and Beth Sipantzi, owners of Precision
Windsports, AirBorne’s eastern U.S. distributor,
recently toured the Australian countryside in an
AirBorne XT 912 during their visit to the factory
in Redhead, New South Wales, Australia.
Like a Honda Goldwing of the air, the AirBorne XT
912 offers comfortable aerial touring.
Racing to be the first weight-shift S-LSA
In early January, the FAA accepted the ASTM consensus standards
for weight-shift control (WSC) aircraft, commonly known as trikes.
The agency’s action paved the way for trike manufacturers to certificate
ready-to-fly machines as special light-sport aircraft (S-LSA). Now,
the race is on to see which company will be the first to complete the
steps necessary to show compliance with the newly approved standards.
One company in the running is
AirBorne Australia, and it is already
accepting orders for its S-LSA model,
the AirBorne XT 912. How can it be so
confident this model will comply? Its
machines already meet Australia’s tough
certification standards, so the effort is
primarily one of paperwork. (Though
preparing documents to the FAA’s precise
requirements is no trivial task, as
anyone who has tried to correctly fill
out the sport pilot certificate application
knows.) Interestingly, Australia is
one of two nations-Colombia is the
other-that have accepted the sport
pilot/light-sport aircraft (SP/LSA) rule
as part of their national program.
Welcome to the AirBorne S-LSA
No one knows who will be first to certificate
a trike as an S-LSA-Air Creation
of France is another strong competitor
as its aircraft already meet the
demanding British Civil Airworthiness
Requirements (BCAR) standards. But
AirBorne’s declaration that it has the
process underway puts it at the lead of
the parade, at least for now. And, this
company has a solid track record of
meeting its promises.
In the 30 years I’ve been flying
and writing flight reports, I believe
I’ve flown all the AirBorne models;
the company currently manufactures
five-the XT 912, the XTC-582, the
Classic, the Outback, and the Redback.
In addition, it manufactures three different
wings for its chassis-the Sting,
Streak, and Wizard.
I’ve watched the steady improvement
through each generation of aircraft
(and wing designs). In recent
years, I’ve been impressed the company
could further enhance an already
well-built aircraft. This is especially true
of the design of its wings, a component
that has received intense focus over
three decades. Still, AirBorne’s designers
constantly improve the product.
In my experience, the XT 912 is
clearly AirBorne’s best model, although
I also like the lighter, simpler, and lessexpensive
Outback model with a single-surface Wizard wing. But it is the
XT 912 model with its properly named
Streak wing that has already earned
an experimental light-sport aircraft (ELSA)
airworthiness certificate-Terri
Sipantzi’s two-place trainer recently
made the transition from ultralight
trainer to E-LSA-and it may soon
show compliance as a fully factorybuilt
model that can be used commercially
for training and rental.
Once a company puts its aircraft
through the compliance process-a
tall stack of paperwork that must be
completed precisely-and adds features
such as the costly Rotax 912
engine, the aircraft’s price rises significantly.
Trikes, which once retailed for
$15,000-$20,000, can now soar well
beyond $30,000 (though lower-cost
models remain available).
In 2005, Air Creation’s Tanarg set a
new price point for trikes, selling in the
United States for more than $50,000.
In comparison to the Tanarg and to
most fixed-wing S-LSA currently on
the market, the AirBorne XT 912 in full
regalia is a relative bargain in the high
$30,000 range. Given the availability
of financing, these prices are well within
reach even for those pilots working
on more modest budgets.
A Whole New Design
AirBorne’s introduction of the XT 912
starting in early 2004 represents a new
design for the Down Under manufacturer.
The XT 912 may not look all
new to AirBorne aficionados (its design
shows some hints of previous models),
but to strap on the potent 80-hp,
four-cylinder, four-stroke Rotax 912,
AirBorne’s designers knew they needed
a structure that could handle the
additional thrust with confidence. So,
XT’s structure was designed around the
powerplant, and the XT trike frame is a
completely new chassis.
On the day I flew the XT 912, I also
had the opportunity to fly the simpler
Outback with a Wizard wing. This
lower-cost model felt nearly as powerful
as the XT 912 even though it is
equipped with the much less potent
65-hp Rotax 582 engine. The similar
feel no doubt comes because the
Outback’s weight is significantly less
than the XT 912, and its wing is a
higher-lift design. To me the similarity
of feel is a credit to designers who
have correctly matched engine power
to chassis and wing design.
The airplane equivalent of a Honda
Gold Wing motorcycle, the XT 912
is a deluxe model for AirBorne. One
look at the instrument panel in the aircraft
I flew made this point. Centrally
located in the panel was the Skydat
GX2 avionics package. To the right of
this multi-function, large-screen instrument
was an electronic switch panel
that provided the master switch, starter
button, and a circuit breaker. GPS users
will appreciate the power source plug
on the far right.
To the left of the SkyDat screen
was a large airspeed indicator (ASI). A
label on this instrument gave information
for three AirBorne trike wings: the
Streak, Edge, and Wizard. Although the
Edge wing is no longer in production
at AirBorne, the company continues
to have ASIs made showing speeds for
that wing as many are still operating
in the field. VNE markings also appear
for each wing.
While flying the XT 912, the round
analog ASI, measuring in knots, agreed
remarkably well with the information
presented on the SkyDat engine information
system. In a central T-panel
below the SkyDat screen was a compact
2-inch round communications
radio surrounded by switches and plugins
for the intercom system. While it’s
certainly a space saver, using this radio
may require you to remove any gloves,
as the switches are small and rather
closely arranged.
My test XT 912 trike had a trim
wheel and cable linkages that trike
builders generally call a “trimmer.”
XT’s trimmer was easily operated. The
large round knob has protrusions to
help orient the trimmer’s position and
to provide a secure grip for manipulation.
In contrast to the radio switches,
the trimmer could easily be used while
flying with gloves.
I discovered it didn’t take many
twists to make the trimmer go stop-tostop.
Yet this trim system didn’t seem
as effective as ones I’ve flown on some
other trikes. At a level altitude with the
engine set in the low 4000 rpm range,
moving from one end of the trim range
to the other made 6-7 mph of difference,
whereas trimming some other
brands has produced airspeed variances
closer to 20 mph. Yet the device will
reduce fatigue when you must hold the
bar back or push it out to achieve your
desired in-flight speed.
In the open-air cockpit of XT 912,
seat side rails provide a location for
other controls. The choke is to the left
and the throttle to the right, under the
right knee of someone in the back seat.
As with virtually all trikes, the primary
throttle is a foot pedal on the right side
of the nose wheel assembly. The front
seat occupant’s left foot works a brake
equipped with a parking lock feature.
The mast of the XT 912’s chassis folds
independently of the engine, allowing
the bigger powerplant to remain well
secured even when the trike is broken
down for transport. Most trikes,
including all of AirBorne’s models, can
be folded quite small for transport on
a small trailer or in the rear of a larger
pickup truck. A gas strut is used to help
lift the beefy wing above the carriage,
which facilitates re-assembly by one
person. That’s good, as the Streak wing
by itself weighs more than 100 pounds
and must be raised well above the chassis. High-quality Fournales oleo-pneumatic
shock absorbers are used as rear
suspension. At the aft of the carriage,
XT 912’s polyethylene fuel tank has
been cleverly shaped to allow the pilot
to check quantity while seated. Such a
simple method is a fuel “gauge” that
can never fail.
The XT 912 uses a metal-framed seat
back to keep the front-seat occupant
from leaning heavily into the legs of
the back-seat occupant. The seat back
pivots forward to allow easier entry to
the rear seat, and it can be adjusted to
accommodate pilots of varying sizes.
Optional instructor control bars allow
a qualified student to fly from up front
while an experienced teacher sits in the
rear, able to make changes or demonstrate
flight techniques as needed.
The XT’s nose wheel has a trailing
link suspension with a shock absorber,
making taxiing positive and comfortable.
Though you still have to become
accustomed to weight-shift aircraft and
their push-right/turn-left steering, a
tight turn radius is possible. Durable
main gear suspension can absorb some
rough fields or hard landings, and wide
tires offer good traction. Aerodynamic
fins built into the main wheelpants
truly do aid directional stability (and in
fact are rather necessary if the nose pod
is as large as it is on the XT 912).
AirBorne’s speedy Streak wing, the
standard on the XT 912, has been load
tested to 5,432 pounds permitting a
992-pound maximum takeoff weight
at a +6g ultimate load. Some underinformed
observers think trikes look
flimsy because of their free movement
of wing to chassis, but those folks simply
don’t understand the design of
these machines.
Launching the XT 912
Stomp your foot on the XT 912’s throttle,
and you get an immediate and
unmistakable response. Clearly the XT
912 has an excess of power, and it
launches with boisterous enthusiasm.
I anticipated this and took off my first
time at around 75 percent power. It
was still a fast launch. The XT combines
an 80-hp engine with a Bolly carbon-fiber, three-blade prop to produce
power aptly described as “awesome.”
As I’ve often found with 912-powered
ultralights, careful application of
the throttle is best. Despite swift acceleration
down the runway, the Streak
wing is built for speed, so we didn’t
break ground as quickly as with slower
flying, high-lift wings. Still, you need
to be ready for liftoff; taking an instructor
along for your first liftoff is wise,
even for experienced trike pilots. I measured
climb at better than 1,000 fpm.
In the XT 912, application of full
power dramatically moves the carriage
relative to the wing, yawing it by the
P-factor. For my taste, the 80-hp Rotax
is more power than you need, but no
one is offering an ASTM-approved, 65 to 70-hp, four-stroke engine that might
be a better fit.
Too much power or not, in flight
the Rotax 912 purred along in a comforting
manner that sets a pilot’s mind
at ease. Plus, Rotax has built a service
system for the United States and most
other countries that assures owners
can get any help they need. And the
XT 912 can cruise quite comfortably
at 75 mph, a pace that will keep up
with most fixed-wing two-place ultralight
trainers. It’ll run over 85 mph if
you want, with the never-exceed speed
(VNE) set at 93 mph. For a trike, this
definitely qualifies as swift. I’m only
familiar with one production model
trike that will sustain faster speeds,
the Pegasus Quik, and only someone
with considerable trike-flying experience
should fly it.
One downside to the power, given
the XT 912/Streak’s higher speeds: a fullface
helmet is a requirement. Even the
pull-down visor on my military helicopter
helmet would not have been sufficient.
Too much air would have come
blasting up under the visor. Personally, I
don’t find the helmet requirement burdensome,
but those who prefer headsetonly
flying may feel differently. But, be
advised; an insect strike in the face at 85
mph will ruin your day.
Recoil shoulder belts are standard,
and AirBorne has worked with BRS to
make a bracket that facilitates mounting
these emergency parachutes.
Smooth In-Flight Controls
When I flew the XT 912 with its Streak
wing, I was fortunate. Earlier that day
the air had been gusty and changeable,
but as I prepared for takeoff, smoother
wind conditions prevailed. It’s always
easier to tell how an aircraft flies when
you don’t need to filter out the effects
of rowdy air. It was easy to tell that the
XT is a stable flying machine; it flew
hands off quite readily.
Despite carrying a substantial carriage
and heavier powerplant, the XT
912 was not particularly heavy in handling.
AirBorne has achieved better
handling compared to other 912-powered trikes. The secret is in the wing,
naturally, but keeping the sturdy chassis
as light as possible is still helpful.
Yet compared to a single-place trike
or a 582-powered single-surface wing/
two-place trike, I can’t say the XT 912
Streak has “light” handling.
However, the latest Streak wing –
now in its third iteration-continues
to display much-improved handling.
Roll in and roll out pressures
are much reduced from earlier higherspeed
AirBorne wings such as the Edge.
And the Streak wing has a much more
predictable feel in higher-speed cruising.
The wing felt solid at 75 mph,
though the trimmer is useful to relieve
pilot fatigue.
The Streak wing is accurately named;
I found it could reach 85 mph without
much physical exertion. AirBorne cut
its teeth making hang glider wings
(and it still does), and hang glider pilots
are demanding about sail cleanliness
because any ripple in the wing surface
can decay glide efficiency. The Streak
revealed superb sail work. I noticed no
flutter even when flying at the fastest
speeds I could sustain. This, in turn,
helps achieve greater speed.
In addition, the Rotax 912 yields a
quieter operation and gets better fuel
economy than a 582, even though it
has 15 extra hp.
As I approached for landing, I was
advised to make an attitude landing.
This technique-practiced by Navy
carrier pilots among others-recommends
you set a pitch position and
hold it until near touchdown. I’d also
been told to use a 60-mph approach
speed. These instructions stopped me
from using older trike-flying techniques.
If I’d pulled in, as I’ve done on
many slower flying trikes, I would have
ended up flying much too fast. Pull the
nose down on the XT/Streak and you’ll
quickly exceed 80 mph, much too fast
for a normal landing. Even at 60 mph
I floated well down the runway. Later
I found I could make approaches at
50 mph or even less, but the 60 mph
number is a good starting figure.
Thanks to the Australian government’s
certification program, the XT
912 with the Streak wing is tested as
thoroughly as any trike you might buy.
In flight, I found mild stalls despite
the wing’s speedy ways, and the Streak
wing is pitch stable. Because it’s a
weight-shift machine, you’ll find no
adverse yaw.
Purchase From Whom?
Over the years, AirBorne has had a central
distributor who handled customer
orders directly. The company still
uses what might be called its “legacy”
dealers, but in the last couple of years,
it has developed well-established East
and West Coast representatives in the
United States, each operating full time
in their businesses.
Both western-based Scott Johnson
(US Airborne) and eastern-based Terri
Sipantzi (Precision Windsports) are
experienced trike pilots who understand
the new sport pilot/light-sport
aircraft rules and procedures. Each is
well prepared to assist new customers
and to establish and train new local
area dealers. I believe this to be the best
arrangement yet for the far-away manufacturer,
especially as it also accommodates
some longtime dealers in a
two-tiered program.
AirBorne is a professional company
with many years of experience.
AirBorne’s principals regularly attend
the major American air shows, even
though doing so means a long airline
flight. But they know customers ultimately
like to meet the people behind
the product.
The XT 912 is a well-equipped aircraft.
Naturally, the Rotax 912 comes
with electric-starting, in-flight trim;
remote choke; fuel shut-off; front
and rear wheel suspension; front
wheel drum brake; and an 18.5-gallon polyethylene fuel tank with
built-in quantity indicator. The XT
912 breaks down easily for transport/
storage, and is ready to fly with minimal
assembly after removal from its
shipping crate.
The base selling price for this model
in early 2006 is $38,463. Only a few
options are offered, or needed, because
even optional carb heat is standard on
the XT. The most popular options are
instructor bars, a BRS chute, a Lynx
intercom system (with helmets), and
a radio. Shipping by air adds $2,659 to
the price. Shipping insurance is 1 percent
of the invoice value and covers
loss or damage to the destination port.
You can save a little money if you handle
customs clearance yourself, but if
you prefer, your dealer can manage this
for you. Local taxes vary by state and
are handled by the customer as part of
his or her state registration.
However you choose to configure
your AirBorne XT 912 Streak S-LSA, I
predict you’ll become a satisfied customer.
Those who haven’t tried weightshift
control aircraft ought to contact
Terri or Scott and take an introductory
flight. Flying a trike is simple and
enjoyable, and when it’s an AirBorne
XT 912 Streak, you’re in for a treat.
AirBorne’s trikes live up to the Aussie
cowboy heritage; they’re built tough
for hard use. Even if you never see the
Great Australian Outback, you’ll love
the sturdy construction of these aircraft
for a long life of flying.
| Seating | 2, tandem |
| Empty weight | 476 pounds |
| Gross weight | 992 pounds |
| Wingspan | 32.4 feet |
| Wing area | 167 square feet |
| Wing loading | 6.2 pounds per square foot |
| Length | 11.3 feet |
| Height | 11.5 feet |
| Fuel Capacity | 18.5 gallons |
| Kit type | Fully assembled |
| Airworthiness | Certified SLSA |
| Build time | Minor assembly from shipping container |
| Standard engine | Rotax 5821 or 9122 |
| Power | 66 hp at 6,500 rpm |
| Power loading | 12.4 pounds per hp |
| Cruise speed | (middle hole) 45-60 mph (forward hole) 75 mph |
| Stall Speed | 39 mph |
| Never exceed speed | 93 mph |
| Rate of climb at gross | 770 fpm |
| Takeoff distance at gross | 590 feet |
| Landing distance at gross | 575 feet |
| Range (powered) | 350 miles |
| Fuel Consumption | 3.3 gph |
| Notes: | 1also available with the Rotax 503 engine (2000 Article). 2Rotax 512 UL (2006 Article). |
| Standard Features | Rotax 582, ASI, altimeter, hourmeter, easy breakdown for transport/storage, in-flight trim, remote choke, fuel shut-off, front and rear wheel suspension, front wheel drum brake, 10-gallon polyethylene fuel tank with quantity indicator, powder- coated airframe, built ready-to-fly (with minimal assembly from shipment crate). |
| Options | Choice of engine (Rotax 503 or 582) and choice of wing (Streak, as tested, or Wizard single-surface wing), electric starter, 4-blade prop, additional instruments, ceramic coating of exhaust, intake and exhaust silencer, and ballistic parachute. |
| Construction | Aluminum airframe, fiberglass fairing, professionally sewn Dacron wing. |
Design
Cosmetic appearance, structural integrity, achievement of design goals, effectiveness of aerodynamics, ergonomics.
Pros – New wing handles resoundingly better than earlier AirBorne double-surface wings. Chassis and wing both have Australian ultralight certification, a tough program that should assure buyers. As good as the better European trikes but with an Aussie touch. Test model is top-of-the-line offering; a simpler trike chassis, smaller engine, and single-surface wing can also be selected.
Cons – One drawback of certified designs is that they don’t change much and neither has the AirBorne Edge trike (though obviously their wing did change). No matter how well it’s built or how it has proved itself, many ultralight pilots are not interested in trike concept. Tailless aircraft are also foreign to many conventionally trained flyers.
Systems
Subsystems available to pilot such as: Flaps; Fuel sources; Electric start; In-air restart; Brakes; Engine controls; Navigations; Radio; (items covered may be optional).
Pros – One of the early trikes with an in-flight trim system. Though it may seem unusual to pilots accustomed to trim tabs, the trailing edge tension system is remarkably effective. In an elegant design that can never fail, fuel tank shape helps pilot check quantity. All trikes have good repair access, better than most fixed-wings. Easily found choke and other engine controls.
Cons – Trim direction indicator is not fully intuitive; label mounted awkwardly. Braking only at the nosewheel can introduce some pilot confusion while also steering (though it’s no harder than heel brakes, in my opinion). No flaps or other devices to vary speed on approach (other than the trimmer, that is). No braking from the rear seat.
Cockpit/Cabin
Instrumentation; Ergonomics of controls; Creature comforts; (items covered may be optional).
Pros – A metal-framed seat back keeps the front occupant from leaning heavily into legs of the person in back. Taking the European guide, AirBorne also uses intake silencers and exhaust systems that greatly reduce noise. Instrument panel was easier to read from the rear seat than in the past; excellent from up front. Extended control bar gives an instructor good control over student input.
Cons – Some pilots simply don’t like tandem seating and those who do may not care for the close motorcycle-like seating of the Edge. Quieter engines cost more money than noisier ones. A radio may need to be carried on your person or mounted creatively. No cargo space except some stash pockets. Seats do not adjust fore and aft. No shoulder belt up front.
Ground Handling
Taxi visibility; Steering; Turn radius; Shock absorption; Stance/Stability; Braking.
Pros – Nosewheel provides trailing link stability and modest shock absorption to make taxiing more effective. Trike maneuvering is much more versatile than fixed-wings, which can’t duck-and-weave. Very tight turn radius is possible. Tough, effective main gear suspension can absorb some rough fields or hard landings (not that I made any). Wide tires offer good traction.
Cons – Nosewheel suspension is hardly needed with trike’s loading aft much more. Footrests don’t offer much support on bumpy terrain; no heel rest. Steadying a trike wing in strong, gusty conditions isn’t much fun (but then, neither is flying in such weather). Some pilots will find it hard to adapt to the standard “wrong-way” steering even though control actions are similar to a bicycle or skis.
Takeoff/Landing
Qualities; Efficiency; Ease; Comparative values.
Pros – Trike takeoffs may look unusual but they don’t feel that way; Edge is a stout chassis that imparts a good feel for the terrain. Both seats enjoy nosewheel steering. Visibility so far below the wing (over 5 feet) yields a wide-open view in all directions except straight up. Energy retention in ground effect is good enough to make flaring easy. Good suspension and fat tires make smooth landings.
Cons – With its speedier wing, more space is necessary to take off and land the Edge/Streak. All trikes still suffer somewhat in crosswind conditions though technique has overcome much of the restriction. Control over landing approach path is limited to power use and good planning. Some conventional pilots have trouble with the chassis orientation under the wing at liftoff (swings forward).
Control
Quality and quantity for: Coordination; Authority; Pressures; Response; and Coupling.
Pros – No question: The best attribute of the Edge/Streak 2000 trike from AirBorne is sharply improved handling. Roll effort was significantly decreased while retaining the satisfying stability of AirBorne wings. Very predictable flying; wing goes where you want quite well and stays put once you’re done maneuvering. Did I mention I loved this wing? Trimmer helps relieve pilot input.
Cons – Still not a one-handed flyer like some hang glider wings on light trikes (but then for a bigger 2-seater this isn’t really expected). If weight-shift control puzzles you, then you may never get its simplicity; many 3-axis veterans can’t make the switch. Crosswind controls are nonexistent. Precision turns to headings still not as crisp as on 3-axis ultralights.
Performance
Climb; Glide; Sink; Cruise/stall/max speeds; Endurance; Range; Maneuverability.
Pros – The wing is called a Streak for good reason: it’s fast. Top speed seen during evaluation was 86 mph, enough to convince many that trikes are not slow. Same can be said for speedy runway departures. Very clean sailwork helps speed, says factory, and also brings a glide ratio better than many 3-axis designs. Very quiet operation. Rotax 582 pushes the Edge/Streak aloft at almost 800 fpm.
Cons – For a speedy wing and an advanced, well-executed design, I’m surprised the company doesn’t use faired control bar downtubes or kingpost (changes probably held back by the cost to redo certification). The Streak will be too speedy for what some pilots want from their trike. Rotax 582 guzzles more fuel than the 50-hp Rotax 503.
Stability
Stall recovery and characteristics; Dampening; Spiral stability; Adverse yaw qualities.
Pros – Government certification programs are minimum standards, but AirBorne has nonetheless passed tight scrutiny by the Australian officials; by itself, this speaks well of the stability. Stalls are particularly mild, possibly a surprising fact for such a speedster wing. Though it’s tailless and tautly stretched, Streak is very pitch stable. No adverse yaw.
Cons – It is possible (though hard) to get upset in a trike. For example, inverted aerobatics shouldn’t be done except by the most expert pilots; Streak’s blazing ways could encourage poor judgment.
Overall
Addresses the questions: “Will a buyer get what he/she expects to buy, and did the designer/builder achieve the chosen goal?”
Pros – Stable company for many years with certified design (CAO 95.32). Very nice execution throughout without losing the Aussie-tough image cultivated Down Under. Despite the huge distance between the U.S. and Australia, company representatives come to the main American airshows; buyers like to meet factory personnel. Shipments to the U.S. are handled smoothly and packed trikes need only minimal assembly.
Cons – Trike buyers have other brands to choose from and some will be less expensive (as tested, this Edge/Steak ran about $18,000 delivered). AirBorne offers a base trike chassis for far less for those who want to build. While trikes are gaining in popularity, they’re still not mainstream ultralight aviation, which may limit resale. Training must occur in a trike (though another brand will be similar).
If I want to transport this machine in an enclosed trailer, what size trailer would I need? Would a 6 X 12 work? Trailer height would be about 6″.
Hi Joe: Assuming you own this, take a tape measure to it. I am not sure 6×12 feet will be sufficient but perhaps if you put the wing on a rack you attach to the roof.