Test Pilot Review: @neistridlar's NA Stout 168 & 216
A clear day for this deja vu... except these aren't really small but instead really big...
Figures as Tested (Stout 168, 168 passengers max):
Price: 97,730,000 (empty)
Fuel: 2,400 kallons
Cruising speed: 218m/s
Cruising altitude: 6,500m
Fuel burn rate: 0.10kal/s
Range: 5,100km (as calculated)
Figures as Tested (Stout 216, 216 passengers max):
Price: 118,730,000 (empty)
Fuel: 2,400 kallons
Cruising speed: 215m/s
Cruising altitude: 6,500m
Fuel burn rate: 0.12kal/s
Range: 4,200km (as calculated)
It's another pair of Neist Aircraft Company planes for Twin Crown Aerospace to look at, with some case of deja vu to go along with it. Tubular fuselage with delta-like wings at the front and winglets at the wingtips. Seems like we've been here before. Except instead of being on the bottom end of aircraft size, these are on the opposite side of the spectrum.
Initial inspections resulted in judgements in line with expectations for NAC aircraft. Some concern was had over the very small tail controls, but we figured NAC knew what they were doing and decided they should be no cause of concern until proven otherwise. These were two very minimalist aircraft, with only the necessities to function present. Reasonable lengthy planes, before NAC jumped into their odd era of building really long skytrains.
With nothing else to really do except fly them, our test pilot got into the Stout 168 and put it on the runway. We expected everything to go by-the-book as outlined by NAC.
Takeoff was exactly that. Our test pilot pitched up as hard as possible to attempt a tail strike, but while the tail gets dangerously close to the ground, the Stout lifts off just before the tail actually hits. Wheels-up was achieved under 50m/s after a short takeoff run.
On the way up to cruise altitude, we conducted general maneuverability tests. This general flight dynamics test quickly revealed almost everything we needed to know about the Stout 168's flight dynamics. Stability is good, though we find that standard procedure is to fly with SAS turned on, as it has fairly relaxed stability, with sensitive control authority in all axes. Not that it's hard to fly without SAS, but just that it's easier to fly with SAS.
Cruise altitude was achieved in a reasonable amount of time, about 3-4 minutes. We attempted to attain cruise conditions through trimming the aircraft, but without SAS, the Stout was just too sensitive to hold solidly stable flight. With SAS, the Stout remained very firmly in cruising conditions. Cruise characteristics were as corroborated to be as outlined, resulting in the values presented in the quick specifications sheet.
With cruise testing over with, procedure led to engine failure testing. It passed the starboard engine failure test, remaining safely in control, though it is noticeably affected by the asymmetric thrust.
Next was full engine failure. Control authority in all axes remains strong. In fact, our daring test pilot, during this no-power state, decided to test the extreme control authority of the aircraft by pulling the aircraft into a vertical loop after a short, shallow dive, pulling up on the yoke with a speed under 200m/s.
So that happened.
But for the primary test condition, yes, the aircraft does glide well and retain speed well. These excellent low-speed and no-power characteristics meant that it also passed the emergency water landing test excellently.
The mid-speed and low-speed tests were done without SAS turned on. All these tests did were reaffirm everything we knew about its flight characteristics, with no fault found in them.
Landing, of course, was incredibly easy. Touchdown was made at ~44m/s, which we figure could be done at an even lower speed, and was a great end to an overall pleasant flight.
The Stout 216 was up next for testing. Like the Swirlygig, the longer Stout variant is a little heavier and sluggish on the pitch authority, but not significantly so.
Everything, again, went as expected and as outlined in the instructions, so we won't reiterate them. Control authority after complete loss of power was tested again.
Our test pilot, a military combat veteran, was a bit disappointed with the lack of post-stall maneuverability, but ground control reminded that they were in a 40t jumbo airliner, especially one with the engines currently shut down, then said nothing else. Anyways, the test pilot was so excited with ground control giving them clearance to do dumb things with the engines shut down, that they tried doing a barrel roll (yes, not just an aileron roll) after pulling out of a 230m/s dive at 1000m. Daring, but just not quite enough altitude, so the Stout 216 prototype hit the water at ~100m/s, at about a 10 degree angle of impact.
So we guess it's got a really good safety margin.
No matter, we figure Neist Aircraft will make back the money put into it through sales of the aircraft anyways.
With the second Stout 216 prototype (because of course prototypes come in multiples), we did the standard mid- and low-speed flight dynamics testing and found no new noteworthy data to report. Landing was again achieved at a very comfortable low speed of 40m/s with a shallow glide angle.
The last thing we really considered testing was ground handling, which is good with a remarkably small turning circle, and with the added benefit of a small wingspan to help it navigate tighter airports.
For logistics, the Stouts are simple aircraft with a part count on the low end for jumbo jets. They also have only two engines, which reduces maintenance time greatly, and keeps operating costs per-aircraft low. Range is fair to good, and they certainly get very good use out of their fuel load.
Criticisms? Well, there is one we could make. Like the Jupiter SST we've inspected, the Stout has a bit of oddness with its passenger amenities, though not critically compromising like it was in the Jupiter SST. But if we assume first/business class to be in the forward cabins, well, they're actually the ones with compromised downward views due to the wing design. And that's pretty much the only thing we could think of, if that's really a concern at all. Oh, and we suppose that, like the previously inspected HC-2 Country Hopper, some airbrakes might be a decent idea, though having working thrust reversers alleviates this issue as long as the engines are functional.
Neist Aircraft Company's Stout series are excellent with no operational faults at all. The only thing we could comment on was regarding minor passenger amenities. Otherwise, they're easy to fly, easy to maintain, very safe, and on the lower end for initial buy-in cost. They're not fast, but, well, that's the Lotus engine that airliners should be familiarizing themselves with these days, until a faster alternative can be found with similar thrust and fuel efficiency.
The Stouts will make excellent mainstay fleet aircraft.