Peter, 36 years ago I worked as an intern at NASA Langley in the division that was testing high-lift wing devices on RC model airplanes. I worked for a summer in the now-closed 30x60-foot tunnel.

You should be proud: your setup here is rather more advanced than the tech that we had available at the time: simple analog RC, gas engines, and our telemetry (radioing the data back down to the ground) was actually a second RC control transmitter mounted in the airplane, connected to some sensors instead of control knobs/sticks, and a receiver on the ground moving strip chart pens around. Your flow visualization tufts are, yes, straight out of the NASA playbook. You could do a bit better for smoke flow vis, by pumping some smoke fluid (we used mineral oil) and heating it with a tiny element at the tip to produce a super-fine and very smooth stream of smoke. But the vape did surprisingly well, if you're just looking at the big picture.


As a flight test engineer, retiring this year from a 35-year Navy test career, I heartily approve of this video. It warms my heart to see the NASA meatball logo again, and you're spot on in many of your conclusions about the aerodynamics.

This is a test in the 30x60 tunnel of high-lift devices: https://cdn.theatlantic.com/thumbor/_hs8pK09YiWYIddQbpX9yQVgoU4=/1500x1064/media/img/photo/2018/05/historic-photos-of-nasas-cavernous-1/w26_L-75-734/original.jpg

Peter,   40 years ago I worked on F4s Phantoms in the Navy.  The Navy F4s used retractable slats and BLC from one of the J79 engine stages to direct air over the Flaps to prevent stalling when deployed.  
The flaps were mechanically connected by linkage to the BLC control valve.  When Flaps were deployed the linkage would open the BLC valve and direct engine air over the flaps to prevent stalls.  Half flaps opens the BLC valve half way, full flaps would open the BLC valve full air flow.    
Maybe try redesigning your engine exhaust mod into 2 sections and have the lower section of the exhaust mechanically connected to the flaps.  Lower the Flaps to half or full position, the mechanical linkage automatically directs airflow from the engine exhaust to flow over the flaps to assist in lift.   Retract the flaps, and the airflow is redirected for forward flight for faster speeds.  
Look at it like the air vents in your car, just try creating a two stage exhaust mod.   The upper stage of the mod always directs airflow for forward flight and the lower section of the exhaust mod is mechanically connected to the flaps to redirect airflow when flaps are deployed or back to normal flight airflow when retracted.  
Just my experience with 60’s technology on Fighters.   Keep up the great work! 😀👍

Honestly, probably one of my favorite plane projects of yours. Simply just pure good aeronautical engineering and problem solving. Plus, it's a gorgeous plane!

6:58 proof everything at night is 10x louder

Please do more of your "wind-tunnel" testing.

That's not just an incredibly well designed plane, iterating exactly on what you wanted to achieve and actually doing it, but also probably the best and most intersting (!) sponsor integration I've seen in a VERY long time. Fantastic work.

Peter you know you could just... get a smoke machine, right? Lol

I remember 30 years ago sketching a STOL RC cargo plane that I wanted to build.  I ended up doing other things and nothing much came of it, but watching this is bringing back memories of what I dreamed it would be.  This is exactly what much-younger-me was hoping to build, but so much better than I was imagining at the time.  Thank you for bringing it to life.

Great work! Propulsion engineer here, and it looked like when you had the nozzles that were losing thrust that the exit area was too big.  The exit area should be close to or a little smaller than the fan duct exit.  If too big, it will be a diffuser and lose a lot of thrust.  Also, it would be cool to see it have flaperons, and retractable slats, since you are going for extreme STOL.

This is one of the better vids I've seen on this channel with the quality of the build and actually iterating the design without mass amounts of jank. Great video!

🛩Hey Peter! I had a wild idea I’d love to see you bring to life: a Voltron-style RC plane! Imagine a large plane that takes off as one unified craft, then mid-flight breaks apart Voltron-style into 4 or 5 smaller, fully independent mini RC planes that each fly on their own! Your creativity always pushes the limits of what RC can do and I would love to see your engineering take on it!

Perhaps you could build a gigantic version of this for Flite Fest this summer.

Peter, in the '70s I was a student intern at the Ames 40x80 ft wind tunnel where the hot project was the AMST (Advanced Medium STOL Transport) program to research upper surface blowing (USB), externally blown flap (EBF) and augmentor wing (AW) models to become help add to the airlift capability of the C-141 and C-130s.
The results of the tests led to the YC-14 (USB) and YC-15 (EBF) test airplanes, with the YC-15 morphing into the C-17, which has become the long haul workhorse after the C-141 was retired.
Your building and testing process with the USB was extremely similar to what we did, with similar results, and the Russkies developed a USB transport, the An72 Coaler for both civil and military applications.
I really enjoyed reliving the process thru your trial and error, and send congratulations for a job well done!!

This video really stepped the channel up a notch. While I love the goofy videos with exploding stuff, this one had me mesmerized. I would love to see you push slow flying even slower,  like walking speed or slower. Great job!!!

12:02 just casually flying your RC plane, indoors, right next to an F22 and the friging Bird Of Pray demonstrator. Big trust in the museum staff.

Man, you really must've been struggling with the algorithm. This is one of the coolest of your videos I've seen and I didn't see it until a year later.

I have a 30 minute lunch. Peter uploads a 30 minute video. Flawless.

@ 19:42, This reminds me of back in the day, shotgunning blunts, an chillin with the set.

Been a fan of these old STOL programs. The YC-14 was a neat looking plane as was McDonnell Douglas's entry. Love that YC-14 though! The 2 NASA QSRA birds were built off of the kinda ugly DeHaviland Caribou. Love your modification of the old Foam & Tape cargo design! Looks like an An-72 which is neat! One of your best/my fave videos! Thank you for deep diving into this one! BLCS is a neat concept. The F-104 used it to help the it with slowing down with its tiny wings.

EXCELLENT work Peter!  I love seeing "hard science made fun", and you do it better than most anywhere. :D

Quick note on the airflow during stall:  It's not whether it's "turbulent" or "laminar", it's about whether the Boundary Layer is attached at all.  You can have a turbulent boundary layer, but as long as it is attached to the surface, the airfoil will be "working".  Turbulent vs. Laminar has more to do with drag.  What you're showing with the slats (which was awesome BTW!) is how they help the Boundary Layer stay attached at higher AoA, preserving lift longer.

Great job!