T-REX Kit

T-REX

Specs

Wingspan: 85"

Engine: OS LA46

Radio: 5 channel

Servos:
HS-322HD (5)

Discontinued

Previous support documentation soon to be available again.

Large Sport Trainer

Of all the developments we have offered, the T-REX has captured our interest the most. Why? It's appearance is somewhat norm, however, closer examination reveals interesting qualities. For the most part, the fuselage is the centre of all utility business. With lots of room for oversized fuel tanks, batteries, cargo and the sort, it is clear that simplicity works best when dealing in the business of having fun. We kept the fuse clean of complex formers and fancy shapes, and have given the greatest amount of allowance for engine range and undercarriage configuration. The new hatch ensures a positive lock when closed, and an easy method to reopen.

Holding the wing in place is not a laborious process. A simple locking fork slides into place - having no need for any bolts to hold anything down. This makes setup a snap, and removing the wing takes only seconds.

The tail is straight forward - durable and clean. No need to get too complicated here as the large horizontal stab provides loads of stability and authority. Keeping it simple also means keeping it clean. The rudder is controlled from within. No unsightly connections on the outside, yet easy to access from the rear opening.

For those who want to put that extra engine somewhere, the T-REX firewall is all too accommodating. With room to put a large 4-stroke engine up front - yet requirements allow even a modest .40 2-stroke to perform surprisingly well.

The wing of the T-REX is a compilation of various technologies. The wing is first nestled into the fuse, rather then placed on top. This gives it more axial style rolls - being so close to the thrust line.

The airfoil used is an Eppler E197, a low reynolds airfoil designed for this particular size/application. The E197 is very efficient with gentle stall characteristics and excellent lift properties. Laminar separation is gradual and even, giving a "mush" stall behaviour.

The T-REX wing also has NASA "droop" properly designed into the outer ends of the wing. The NASA droop extends ahead 3% of the wing chord and droops 3˚ below the forward MAC of the E197. The droop, or lower incidence profile, allows the outer section to stall later then the majority of the wing. The droop is proportioned at 38% of the effective span to optimize it's effect. The droop being positioned ahead of the ailerons, means the ailerons will still be operating long after the majority of the wing has stalled.

The droop incidence is not the only reason the droop resists stall. The droop is not just an extension of the foil, it is a continuation of the upper foil curvature. The droop is more accepting of air at higher incidences due to its extended profile that continues curving ahead of the E197. More air is allowed to roll over the top - thus keeping the foil from stalling. This arrangement might suggest a loss in lift. But with the droop sitting further out by 3%, more lift is provided by the deeper chord.

The ailerons on the T-REX wing are a familiar design to few. These are known as Frise [Freeze] ailerons. Frise ailerons do not pivot the same as conventional ailerons. There is no gap for air to pass around them and the geometry of a frise aileron produces a clean and tight profile when deflected down. But when they are deflected up, something else happens. The lower side has a deeper face then the upper side, and since the hinge is on the leading edge of the upper side, the lower side - being deeper - digs out into the air-stream producing greater profile drag to pull back the wing. This in turn produces yaw, and gives the plane the effect of a co-ordinated turn.