A further development of the Delta single seater is the Verhees Delta D2 two seater. Besides the demand for an extra seat there was also the need for a very large cabin with an even floor, a high payload and a longer range. As engine the very common 100 HP Rotax 912S is chosen.
The planform of the basic wing is the same as that of the D1. Overall dimensions are 1,2 x bigger than the D1, which gives it in theory 1,44 x as much wing area, in practice this is 1,5 x due to the turtledeck that extends behind the wing.
A real travelling aircraft
The aircraft is designed for travelling, with a tank content of 2x 70 ltr the endurance can be as long as 8 hrs, at a speed of 220 km/h the fuel consumption is 16 l/h, endurance 7 hrs with ½ hr reserve, so the range is 1540 km (with reserve, no wind).
At a speed of 240 km/hr the consumption is 18 l/hr, this gives a range of 1480 km.
Flown single with extra tanks the endurance can even be enlarged to 18 hrs with a range of 4000 km!
Camping can be done inside the aircraft due to the very large cabin and the even floor. The seats are foldable for this purpose.
The empty weight of the D2 prototype is only 275 kg, giving it a payload of 325 kg, so more than its own weight!
Even with full fuel and 2 occupants a lot of bagage can be carried.
As with the D1 the wings are foldable to save the money for the hangar. Unfolding and fixing the wings and taking the aircraft from the trailer only takes 15 minutes.
The stringers of centre section and outboard wings main spar are connected with brackets and inner hex.socket bolts. These bolts can be tightened by means of a long spanner that goes in via the wingtip through a plastic tube. Tightening is by torque: the long spanner has to turn 45° back after tensioning, this secures the right torsion. The advantage of this sytem is that there are no tight fit parts in the wing connection that can wear. The bolts are industrial bolts that are commonly availabe and can be changed easily.
The D2 has one stick in the centre that can be operated by the 2 pilots, as a consequence 2 gas levers are installed. The brake lever, operating the hydraulic disc brake of the main wheel, is mounted on the stick, the oil reservoir is integrated in the handle.
In the D2 prototype all the instruments are on the left side of the instrument panel: EFIS, ASI, altimeter, slip indicator and autopilot, on the far left are the engine instruments, voltmeter, propeller lever, and radio and transponder, keeping the centre console free for the iPad for navigation. On the right side is a glove compartment. Of course this can be adapted to ones personal preferences.
In the tunnel is the fuel selector with fuel pressure indicator, in this way no fuel lines are inside the cockpit.
The monowheel landing gear with steerable main wheel and fixed tailwheel ensures easy take offs and landings, no risk of ground loops and aileron control is there before take off.
The tailwheel with suspension is in the belly fin. This belly fin is attached to the wheel fork and goes up and down with the wheel suspension, so the wheel protrudes only the minimum. The belly fin is easily removable e.g. for changing the tire or checking the suspension.
Getting in and out
A removable rope ladder is used to climb onto the wing which has reinforcements next to the cockpit to stand on.
The structure is of aluminum with ribs made from hard foam, this, together with the light but powerful Rotax, gives the very light airframe. The load carrying parts are all rivited.
The canopy is of the sliding type, advantages:
- with much wind it stays stable on the aircraft
- on warm days you can taxi with the cockpit open
- no chance of opening in flight unintentionally