Dhumla Flight Trial 3

weather conditions are improving as expected after high winds earlier today. Dhumla is rolled out and ground crews are prepping the aircraft for Flight Officers Tedman & Aldeny, who are in the ready room suiting up ahead of briefing. Wheels up @ ~00:10 UTC

running a bit behind schedule, flight crew has radioed for taxi/takeoff clearance. Today's test will finally put the aircraft through its paces while in the air and cover many things: stalls, G-loading, engine-out and service ceiling

good departure from Rwy09, aircraft is climbing out along runway heading for 2.5km. Most maneuvers will be done over the Kerblantic just east of KSC. We have our rescue boat in the area ready to move in should the aircraft end up in the water for whatever reason

trimmed level at 2.5km ASL, Tedman has brought the aircraft around in a broad circle to setup for a power-on stall, which will leave the throttle set to 80% (cruise) and pitch the nose up as much as 60° to initiate a stall, followed by recovery

aircraft behaved extremely well during the stall. Nose still high at the time of excessive AoA, it pitched straight over without roll and recovered easily out of the resulting dive. Aldy reports Tedman is now climbing and coming about for the next stall test

flight crew is now set for a power-off stall from 4km. Throttle has been reduced to idle and aircraft will hold pitch level until it can no longer be maintained. Stick neutral once dive begins, we will see if the aircraft can recover itself w/o throttle up

~2.5min before airspeed dropped to stall and aircraft nose-dived towards the ground. It did begin to slowly nose up & recover but Tedman had to pull up manually as they passed through 1.5km to ensure they didn't smack into the water. Still - great performance

satisfied with stall recovery, flight crew is moving on to G-loading. Tedman will climb back to 4km then initiate a dive, pulling out at up to 4-5Gs. If the engineers ran their numbers right, the wings shouldn't rip off. Even if we do it twice in a row...

whoo! Reaching speeds up to just over mach 0.7 and pulling up with peak 4.7G and 4.9G we are happy to report the aircraft still has both wings attached 🙂 Flight crew is re-establishing a trimmed-out cruise at 4km ASL before moving on to engine-out tests

autopilot enabled to hold wings level, outer-most port-side engine has been shut down and feathered. Opposite rudder trim has been applied. Throttle began 50% at shutdown and has been slowly increased back to 80% without affecting level flight while holding heading

with one engine still out the aircraft was brought around, throttle reduced back to 50% and now the inner-most port-side engine has been shutdown and feathered. Time to see if that huge vertical tail can do the job it was designed for and hold the aircraft steady even at cruise

with rudder at full deflection and a slight bank, aircraft can indeed hold heading at 80% throttle while maintaining 4km! Aircraft will remain in this configuration a bit longer to collect more data then both engines will be restarted for a climb to maximum altitude

the view out Aldeny's window just a minute ago as they passed through some light clouds and over the mountains, climbing for 9km, maybe even 10km ASL. Throttles wide open, vertical speed is still 10m/s and pitch authority is only half used up

elevators are at full deflection, vertical speed dropping below 5m/s and gradually falling but will remain positive and stabilize soon. Aircraft will continue to slowly climb as it burns off fuel and gets lighter. The first goal will be to exceed Val & Jeb's record of 8.516km

another record broken! Fist-pound in the cockpit as Dhumla zooms through 8.516km and continues climbing, approaching the West Shore Desert with comms and telemetry being relayed through Umbarg aerial. Progress will continue to be slow, vertical speed @ ~2m/s

aircraft is heading back to KSC, leveled off at 4km ASL after the flight crew declared an emergency and made a rapid descent once loss of cabin pressure was detected by the onboard systems. They are back in breathable air now, report aircraft feels structurally sound

coming around for final approach Tedman has had no trouble controlling the aircraft as normal and Aldeny found no leaks in the cabin (cargo hold is not pressurized). They have been cleared for landing back on Rwy09, emergency vehicles have still been prepped & are standing by

the aircraft is taxiing back to the HAB after an uneventful (if still a bit rough) landing. It was scheduled for downtime & inspection after this test anyways but it seems there will be more to look at than we thought. Glad to have the crew home safe!

incident report from the last Dhumla test flight (kerbalspace.agency/?p=8759) has been released. The outflow valve in the rear suffered a failure, lowering pressure in the cabin. Crew response was correct and safeties properly prevented rapid depressurization

valve was repaired, not replaced so further testing can be done to better understand how it failed in the first place if it fails again. Ground crews will roll the aircraft out for flight tomorrow, which will also include a cross-country trip to KGA for a touch & go