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Ryan ST replica performance data

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32fordboy

Well-Known Member
Joined
Jul 10, 2010
Messages
104
Location
Montrose, Colorado, USA
Our Phase 1 testing was finally completed yesterday, so it felt appropriate to share the testing details. It's funny how the plane matured as a design. The initial goal was a to have a plane that was extremely light with an empty weight of less than 700 lbs, powered by the little Mikron engine. Of course, projects mature, which is definitely for the better. Obviously we'll learn more throughout the life of the design, but Brooks tested the plane so thoroughly I have no reason to extend Phase 1.

Our "copy/paste" results are below:

ST-L real-life test results. Keep in mind this is at high Colorado altitudes with only 100 hp. More power or a turbo would really wake up the machine. Some of these numbers are shown in the videos made by Brooks Mershon, so be sure to check them out.

Span: 28’ 6”
Empty weight as tested: 815 lbs
Gross weight: 1350 lbs
Fuel capacity 17.2 US gallons
Engine as tested: Rotax 912uls 100hp
Cruise speed averaged about 85 kts/98 mph
Design cruise speed up to 113kts
Maximum speed attained so far 123 kts/ 141 mph
VNE: 130 kts/150 mph
Approach speed: 60 kts
Landing speed approximately 40 kts
Takeoff and in ground effect by 45 kts.
Landings as short as 700 feet, takeoffs as short as 600 feet at a field elevation of 5,288 feet. Conditions vary significantly. See notes below.

Lowest recorded power-on stall: 25 kts indicated (likely attitude error) at about 9,000 feet with no tendency to drop a wing tip.
Maximum demonstrated crosswind: 12 kts. 8 kts maximum is recommended.
Tested to 14,000 feet
Tested to aft CG with simulated zero fuel. The plane does become more difficult to land, but it didn’t show a tendency to be dangerous.
Climb: approximately 800 fpm solo, 300 fpm dual at about 7200 feet density altitude. Again, more power or a design-specific propeller would help

Barrel rolls, wingovers, and steep turns have been tested. Loops will not be performed in the prototype airplane. Toilet paper dogfighting has been tested several times, repeatedly pulling 3.5-4G while maneuvering. General handling is docile/gentle at slow speeds and quite nimble at higher speeds.

Ground handling is good for a sharp and current tailwheel pilot who doesn’t mind the plane’s long nose. Most landings were wheel landings on asphalt, and the plane really shines doing three-point landings on grass, described as very easy with positive directional control. Kits will sit a bit lower on the main gears for a one degree change in deck angle and will likely handle better yet.

Landing distances are short for the type of plane and, depending on the airport, it can be off the runway at the first taxiway, as is done at Boulder Airport, KBDU. The tail comes down at a speed that was described as laughably slow. As with anything in life, this has its pros and cons. For pilots who prefer a faster landing speed, a clipped wing version is available.

The amount of wing clip has been determined by testing wing loadings in combination with predictions in landing speeds. Clipped wings should, from what we know at the time, increase landing speeds by about 4 kts. In addition, clipping the wings outboard of the flying wires reduces the lift-induced moment on the wings which means that, for no other change in structure, we get a higher limit load. This is opening up the potential for gentleman’s aerobatics beyond what has already been tested.

Stalls are very gentle and the plane would rather not spin. Minor incoordination in stalls has not shown to be a problem if the plane is built as straight as the prototype. Accelerated stalls had very positive control and showed no tendency to break loose when skidding during the stall. To sum it up, if the plane is built as straight as the prototype, it would really rather stay upright and not throw itself into a spin. From what we know, it would take honest effort to initiate a spin. Thus, spins were not tested.

For grins, we tested VGs on the rudder. They surprisingly had zero effect on the rudder. Now I just have to figure out how to remove them without pulling paint.

The stick-based trim system proved to be insufficient on the prototype. Therefore, kits will go back to using the Ryan-style aerodynamic tab. That is better, anyhow, as it offers redundancy.

The biggest issues with the plane were ergonomic, and these have been addressed for the kits. The rear seat will be 1” lower, giving the pilot the option to move down 2” from the current state, or upward with the slightly taller (more scale) rear windscreen. It’ll be based on pilot preference. The throttle has been moved forward. I designed and built 4 different rudder/brake pedals to get them just right. Pedals on the kits will be moved aft 1” to allow better fitment around the front occupant. The front occupant will have more aft elbow room to allow better operation of their throttle.

The cockpit remains wider than a factory ST. Thanks to Glenn Gordon’s extremely careful and deliberate cowl shaping, this is not very noticeable on the ground at all.

The forward baggage compartment has surprisingly been found useless (impractically large for the compromises that had to be made to fit it), so kits now have the rear baggage, and provisions for a belly pod, which is in the works. The benefits are more fuel, more room for gauges, more foot room, more firewall space, easier tank filling. Too many positives.
 

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