BTC Scythe

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BTC - Scythe

The Scythe vehicle uses a thermoplastic airframe that was developed from SBIR Funding. A para-foil recovery system allows for a high performance low drag airframe configuration while being able to slow down for precise short field landings. When combined with a launcher this results in a very small footprint for a very capable UAV system.

With a much higher wing loading than a model speed plane, the Scythe can penetrate weather and turbulence. The clean design coupled with the thin airfoil and high aspect ratio provides a dash speed well over 100 knots, an efficient low power loiter and an impressive glide ratio at speeds in the 60 knot range. This little bird has the performance to run with much bigger mid range piston powered UAV's. The elliptical polyhedral wing de-localizes stress and allows a thin section to be quite strong.

One fact that makes this vehicle stand out from the rest is the recovery system. Without the spoilers or flaps or pilot expertise normally required to land a plane of this type, the Scythe recovery system lets the autopilot or manual pilot land the Scythe on a helipad or small clearing or on board ship. The parafoil system deploys rapidly and causes minimal deviation from the intended flight path. This means it is easy to use. We have had extensive experience in this system and our proprietary methods allow easy recovery in real field conditions.

The Scythe UAV is constructed with thermoplastic materials utilizing a double monocoque structure. Both the structural skin and the large honeycomb cores are made from ABS. The tail plane skin is integral to the fuselage as it is formed from one piece. The cores themselves are two piece monocoque. The bonding of the skins is to all the honeycomb like monocoque internal structure assuring that any damage or de-lamination remains local. The airframes produced using this method are monolithic rather than composite. This results in a temperature stable warp free component. Since the units are made from a mold, a high degree of complexity may be part of the structure and not substantially increase the component cost. The individual formed components are then joined in automated fixtures. Adhesive or bonding agents are applied to the sub components by CNC equipment fitted with dispensers.

The Scythe structure features an 80 oz. fuel tank that is built into the top forward half of the fuselage. The circular cross section provides the minimum wetted area for this long duration vehicle. The payload area is large (entire bottom half of the fuselage) and allows easy adjustment of CG by placement of batteries and other components.

Landing procedure with Parafoil:

1. Cut power to idle, slow plane to approximately 40 knots (interlocked to pitot input to prevent high speed deployment)

2. Deploy Parafoil

3. Add power and continue to fly at 15 – 20 knots

4. Reduce power to land (may be auto-landed safely without flare)

The unique system operates on a rapid deployment dynamic that does not disturb the flight path. Time from deployment actuation to full inflation is less than two seconds. This is because, unlike a parachute, the parafoil wing presents the minimum drag relative to flight in a fully inflated configuration. Those that have attempted to copy our system seem to fail to understand this. The protocol for packing is very simple and can be turned around from recovery to launch (fold and stow chute) in less than five minutes. With the ram air chute inflated the Scythe flies like a gentle park flyer at speeds less than 20 knots. Extended flights requiring very low speeds may be made in the deployed mode. The controls function the same from a flyers prospective whether it is deployed or not and the bird may be landed by autopilot or manual means.

With a one piece wing and removable fin the system is field ready in minutes. The four piece collapsible bungee launcher is a stand alone unit that requires no power source. The long (24') launcher rail has advantages in that a 14 lb Scythe comes off flying at about 40 knots with less than 2 g accelerative force.

A full system consisting of 3 airframes with full payload systems, bungee launcher, ground station with transport cases as well as training service available, performed in cooperation with UAV Pro.