Airframe Comes in 200 Pounds Under Forecast Weight
One of the more
intriguing VLJ projects in the offing, is a quiet effort
from the fellow who designed the Maverick Twin-Jet... a
project that got some pretty solid buzz before it was taken over
and mismanaged into the ground by erstwhile "jetpreneur" Jim
McCotter.
The current plans call for the single-engine Sport-Jet to have a
maximum speed of 375 kts, a normal cruise of 340 kts and an economy
cruise of 310 kts. The SJ's rate of climb is expected to be 2500
fpm, an operational ceiling of 25000', a stall speed of 68 kts and
a landing speed of 80 kts. Sport Jet's range w/IFR reserves are
1000 sm, with a T/O distance of 2300' and a landing distance of
1800'.
While the Bob Bornhofen designed Excel-Jet Sport Jet has been
(somewhat) out of earshot, there has been no lack of activity in
this program.
Conversations with the team putting together the single-engine
Sport Jet have told ANN that the project seems to be missing
something... like an entire 200 pounds of anticipated airframe
weight. After final paint was added on July 15th, the Sport-Jet was
precisely weighed, and while, "the target empty weight had been
2,800 pounds, creative design changes were implemented to lower
that number to 2,700 and then to 2,600. Judicious use of materials,
constant weight watching, and keeping systems simple resulted in
the weight savings."
When the completed and painted Sport-Jet went up on the scales,
the bird came in at 2,275 pounds (not including an anticipated 100
pounds for the future interior installation) -- some 225 pounds
UNDER the reduced target weight. No one at Sport Jet can recall any
equivalent development project that came in so underweight.
For the moment, this weight "savings" will be slightly off-set
since the first test engine is a T-58, an installation that will
add some 40-50 pounds over the future and final Williams FJ33-4A
(which can't be delivered for a number of months). Sport Jet says
that final pressurization installations will add about 15 pounds
more, as well as some 20-50 pounds for de-icing gear.
Bornhofen claims that, "Even after these necessary weights
are added, Sport-Jet STILL HAS 140 pounds of margin before reaching
the lower empty weight target. This weight can be used for
additions caused by FAA certification... which always occurs."
At this time, Bob chooses not to alter the specifications seen
on the website, though more useful load has apparently been gained.
A decision will be made about final specifications after initial
testing and progress made toward certification.
Sport-Jet has a huge cabin, 59 inches wide, and the occupants in
the aft seats can reportedly stretch their legs to full length
without touching the front seats (unless they're pro basketball
players, notes Bornhofen). Actual seat pitch is 28 inches. Entry is
through a split door.
The T-58 makes about 950 pounds of thrust while the Williams
FJ33 produces 1500. Test flying with a reduced fuel load (80
gallons instead of the standard 200) will assure the plane performs
adequately for the initial tests, which they consider adequate to
evaluate the necessary flight handling characteristics at slow and
cruise speeds.
The 4,800 pounds GW, less the new 2,600 pound empty weight
(still allowing for future weight increases for certification),
leaves a useful load of 2,200 pounds. With 200 gallons of Jet-A,
some 860 pounds of payload remains. That leaves a load of four
200-pound occupants WITH 60 pounds of luggage. With four
'FAA-standard' 175-pound occupants; luggage loads can be
increased to 160 pounds or 40 pounds per person. Since Europe has
over-flight taxes on aircraft with GW's over 4400lbs, Bornhofen
promises that he can set the GW for Europe at 4400' and STILL have
1800' payload.
The current Sport-Jet test article is said to be a 92%
conforming vehicle -- mostly due to the absence of the
much-anticipated Williams. The test airframe conforms to 98% of the
certified version, missing only pressurization and de-icing. In
preparation for its taxi and initial flight tests, Excel-Jet's team
of "skunk works" developers, lead by designer Bornhofen, is
carefully preparing Sport-Jet for the first flight... which could
come within days. The following details have now been
accomplished:
- Elevator and rudder flight controls operational.
- Landing gear operational -- gear retracts and lowers quickly
and all the pressure switches working.
- Avionics operational.
- Flaps installed. Flap sync controller box all checked out.
- Brakes installed and bled.
- Engine has been test run.
- Ailerons are mounted along with control bellcrank.
- Radios operational, transponder and encoder tested and
operational.
- Everything that has been installed and tested, has been
properly safety wired and inspected.
Bornhofen claims that this small "skunk works" style of
development differs from all other VLJ projects. Sport-Jet has been
95%+ developed using his onw funds and outside
investment will only come in after first flights have been
completed. Bob is particuarly proud that this program has
been done "quietly" and without great fanfare -- and also
without lots of hype and the obligatory 9and risky) pre-selling of
delivery positions. Bornhofen adds that, "No customer has money
tied up in the development of Sport-Jet. Our policy has been not to
sell any aircraft before the plane was completely assembled and
ready for tests. We are looking forward to the aircrafts
performance and flight handling characteristics."