Each portion deploys independently, driven by the air pressure of the speed through the air. The retractable slats are in two portions on each side. This shows how open the slot is compared to the regular 701 fixed slats, and also how the wing leading edge is sharp, and the slot is much more streamlined, so much less drag when the slats are deployed. This allows much greater airflow through that slot with less drag. Notice that the exit slot is much larger than that of the fixed slats on the 701. The retractable slats give the best at both ends of the flight envelope. Fixed slats are a real compromise problem between slow speed lift, and cruise speed drag. The first 701 plans had the slats mounted so that the bottom lip was below the bottom of the wing, but that caused so much drag and disruption at cruise speed that they had to be raised permanently thus losing some lift at slow speed. All retractable slats in other aircraft, such as the Hellio Courier, deploy downward to increase the camber. The slats deploy not only forward, but also downward, thus effectively increasing camber of the wing to somewhat the same as the thick, high-lift profile of the original wing, so it gives very much the same lift coefficient at slow speed. When the slats are retracted it’s very streamlined. The airfoil is much thinner than the regular 701, and the bottom is semi-symmetrical. When you get to know this retractable slat wing, you realize how draggy and inefficient those fixed slats really are! It’s not just retracting those regular slats at all.
These photos will really how totally different this is from the regular 701 slats. It’s proven to be as STOL capable as anyone could need. It’s travelled over much of Eastern Australia, from Tasmania to the Gulf of Carpentaria, and into lots of short and hairy strips round about. So the pilot prefers to cruise slower at best fuel efficiency for these long trips, and enjoy the scenery.
That gives 150 nm (180 miles) more range with 80 litres of fuel with retractable rather than fixed slats! It’ll fly easily at more than 80 kts (100 mph) even with the 80hp 912, but the rest of the draggy fuselage causes efficiency to go down at these speeds. A 701 with the regular wing without slats burns about 14 l/hr (3.7 gal/hr) for that speed, and with fixed slats more like 17 l/hr (4.5 gal/hr). This aircraft cruises at 75kts (95mph) on 12 litres/hr (3.2 gal/hr), and that’s real genuine figures determined over 800 hrs flying time. It’s even faster and more efficient than the original wing without slats, which we know really well, and very much prefer to those draggy fixed slats which we’ve left behind long ago. With the slats retracted, it’s much faster and more fuel efficient than the regular wing, yet when they’re deployed it has STOL capability pretty much the same as the slatted 701. This 701 is the only one in Australia with the PegaStol wing. That’s really unfortunate, because it’s really good. I say ‘was’ because it’s no longer in production, and last I heard it’s not likely to be, at least for some time. We keep seeing inquiries on the forums asking what the PegaStol wing was like. '09 Flight to the Bight and the South Coast.'18 - High Clearance Trail Bike to South Australia.'19 - Flight to the Farthest Corner of Australia.Aircraft Using Stolspeed VGs Testimonials.