The VSKYLABS SF-25 Falke Project

The VSKYLABS SF-25 Falke Project


The Scheibe SF-25 Falke is a German touring motor-glider which flew for the first time in 1963.

As in all VSKYLABS Projects, aircraft performance, flight dynamics and handling characteristics are the main core of the project. Nearly one hundred hours of pure flight dynamics testing and evaluation were made to bring this aircraft to maximum accuracy in terms of performance and handling qualities.

The VSKYLABS Scheibe SF-25 Project development for X-Plane was approved by Scheibe Aircraft GMBH (although it is an independent VSKYLABS project which is not endorsed and/or affiliated with/by Scheibe Aircraft GMBH). The project is featuring the SF-25 B/C variant (Falke 1700), which is equipped with a 65 hp engine, driving a two-blade wooden fixed pitch propeller (alternator and electric starter are included).

To have some practical idea regarding the aircraft, down below are some performance facts of the Falke, taken from the Schiebe Flugzeugbau GMBH Flight Manual of the SF-25C Falke (May 1990 Edition). This manual and the procedures within will be part of the VSKYLABS Scheibe SF-25 Falke manual for the aircraft:

The Falke can taxi unaided and is steered on the ground with the tail wheel (biased to rudder control). The main wheel is featuring a braking system. Minimum airspeed for level flight is 43 knots (50 mph), and the best cruising speed is about 70 knots (81 mph). Maximum cruising speed is 81 knots (93 mph).

The Falke can be landed with the engine either running or stopped. Approach is at 49 knots (56 mph), and the glide path is being controlled by the wing spoilers. With spoilers extended the sink rate at 49 knots is approximately 3.7 m/s (~720 feet per minute). Minimum touchdown speed is 38 knots (44 mph).The Falke has been flight-tested for take-offs and landings in crosswinds up to 13 knots. Landing run is about 300 feet and can be reduced effectively by the main wheel brakes (which is operated by the spoilers control on the last part of its travel when pulled fully back).

Flying as a glider (with the engine stopped): The aircraft handles very well at 43-51 knots (50-59 mph) with a sink rate of about 1.2 m/s (~230 feet per minute) in a straight flight. Flying the aircraft in X-Plane (as in real life) is a rewarding challenge, as it requires a very clean and coordinated flying. With a little practice and accurate flying, very good thermal climbing is achieved.

Range and endurance: with a 55 litre fuel tank (14.5 US gallons), flight duration may exceed 5:15 hours, covering ~680 km (~422 miles). With 80 litres (21.1 US gallons), flight duration could reach 7:30 hours while covering ~975 km (~605 miles).

Cockpit panel layout: The SF-25 panels are very much different from aircraft to aircraft, having the panel itself taller or shorter, with a variety of avionics combinations. You can find a really...really messy front panel, with switches and gauges scattered around without any logical order, but you can also find more ordered and uniformed configurations too. Same goes to avionics - from almost GA standard to almost a minimal glider type configuration.

Test flights are currently being made with three different variations:
  1. "very equipped", analog panel, with artificial horizon, NAV instruments (VOR/ILS) and so forth...
  2. "G1000" (!), a somewhat very boring cockpit environment for this kind of classic aircraft that is being flown by hand with great skills...
  3. "Minimum requirement" analog panel.
I'm finding the aircraft most interesting to fly as the avionics features drops down, with a "Minimum requirement" analog panel.

Down here are a few **UNDER DEVELOPMENT** screenshots, showing the general principle of a "Minimum requirement" panel layout. This kind of configuration, with slight changes, can be found in many real, flying SF-25's.

Older versions:

Stay tuned for more details, as development is racing to the finish line.

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