Spencer testing Transonic Sweeper 

This RC genre is the Pinnacle of RC planes. Absolutely incredible. I fly lots of RC planes in all sorts of models. 3d, Warbirds,Stol,Scale, Jets, gliders, whatever. But these slope planes that fly in these locations that generate extreme speed off the wind rolling over the top of the ridge then down into the low pressure pocket then back into the high pressure over the ridge just blow your mind. The speed and sound! Just perfection. Adrenaline pumping RC flights. And planes built to withstand the G-load are a work of art and incredible. I have seen many explode. But when a fella gets it right and has lots of exploded planes under his belt the outcome can be truly amazing. Props to the pilot and builder (most the time one in the same) and keep the videos and planes coming. Love it!

1) the engineering on those wings is absolutely nuts, the wing loading must be incredible 2) no way in hell I’d be standing that close, one wrong move on the sticks and you decapitate three people Props boys, that’s amazing

Speed: 344 mph / 553 kmh. This info is from his link in the description. Plane is designed as a test model for lighter winds (in this case 30-40 mph). He's now working on a full design for strong winds - this thing's going to get close to the sound barrier 💣🚀)

I’m going to have to say this is the pinnacle of rc! There’s nothing even close! Fpv drones,turbines,nitro or gas anything and nothing brushless could dream of this rawness!

the wing loading must be incredible

GOD forbid you have to sneeze, or a bug hits you in the eye. Incredible Piloting skills.

This is just beyond what should be real. Never seen anything like that. So fast what a superb model and amazing design.

This airframe sounds absolutely incredible - never heard something quite like it. Initially I thought the video was sped up but this is an absolutely wild kind of flying!

Never been at a site seeing it happen but these RU-vid videos still take my breath away. Tough damn airplanes and great pilots!

Beautiful.. Takes a lot of skill to fly these, but that camera man should get an award....

I love it when I find a video with a ton more views than subs like this. Just looks and sounds unreal. The future's going to be lit because of folks like you. Keep it up!

Amazing. Looks like the test went pretty dang well.

Awesome design & insane build quality. At these speeds, with that wing layout, even slight differences in the wings will cause much trouble.

Wait, so this is just powered by the wind like a glider? That's freakin awesome! Edit: Everybody, please stop explaining to me how this works. I understand the physics of it. I know how a glider works. I get it, "powered" was a poor choice of word to use. I have just never seen anything like this before and it blew my noggin up.

That amount of wing sweep reminds me of a B-52. It also reminds me of a flying razor blade!

Don't forget that transsonig flight requires a swept empennage too. You want any part of the plane go supersonic first, but most certainly not your elevator.

You have hit the nail on the head with this one. Absolutely 💯 perfect sir. Best looking and flying glider I've ever seen.

Have been listening to some interviews with the Perlan 2 pilot and the limits they have reached with the Perlan 2 at height. If another is built its to explore the transonic regions next. They are right on the limit with the current wing.

It flies so pretty and slow the takes off like a rocket. That’s crazy. I don’t think this should be possible but yet here it is

Wow what brilliant engineering and art by design. Just amazing.

Nice!!! That thing is nasty looking! Congrats guys, look forward to seeing it break the record

excuse me? That sturdiness is insane for how thin that is I have to say this is one crazy concept glider

Wow, this gives another dimension to the concept of glide slope

The new bird flies very quietly and smoothly, in a more dynamic atmosphere it will improve the record with good control! As for a familiarization flight, it is very good!

Reminds me a bit of a symmetrical wing V-tail glider that I built in 1980. Not QUITE as fast as this one, but still the fastest at Ivinghoe Beacon in England.

Amazing that the same phenomenon used by an albatross to stay aloft for weeks or months can also take a model sailplane up to transonic speed. Fantastic work and flying! Good luck with the next phase! Maybe we'll be hearing a sonic boom? That would really be something!

Man that's some crazy piloting skills and the plane sounds like a freaking fighter jet.

Fabulous new meaning to Fly Low, Fly Fast, Turn Left.

Amazing flying! My Dad always made my cover our plane in Hi-Viz Pink so that we didn't lose it in the sky. I always hated that. But if I were you, I'd put Hi-Viz Pink on bottom and Hi-Viz Green on top. Using white is the last thing I'd do. A close 2nd would be sky blue.

Awesome plane, fantastic flying spot.

Congratulations. That is wonderful.

I say it all the time, Spencer is cool! Regardless of performance the wings looks bad ass!

This is astounding. I've only recently discovered dynamic soaring even existed, here on RU-vid - and as an engineer living near a fairly steep hill (about 50m height, along the river Rhine in the Netherlands) I'm intrigued what could be done with this energy - how to harness it, perhaps in using it with an angled windturbine somehow....

so beautiful , has the sweep of a Stratojet !

This really is very very impressive work guys. I'm sure you'll be arrested for breaking the laws of physics soon.

Fantastic plane and piloting. I have one suggestion/request -please get one of those furry covers for your microphone. It will do wonders for the video sound on that windy hill and the sound of the plane might yield some info about where the flow is going transonic.

It's very cool. Pilot is very skilled. Any chance of camera on board?

Quite a step up from the Gentle Lady gliders of 40 or 50 years ago, when I flew r/c!😊

Beautiful! What speeds were you registering on the radar gun?

A+ for the cameraman.

So what speed did you manage to attain on this flight?

The g forces that thing is experiencing must be insane, turning that sharply at such night speeds

What a crazy cool contraption. I would be interested to know how much time went into designing those wings.

Holy moly that thing is FAAAASSST. And super slow. INSANE piece of engineering. 🤓😎👍👍

This is incredibly impressive. That speed from a non-powered glider.

WTF? That was incredible. With my awesome reflexes, I'd stuff it those pretty, rocky hills before I even knew what happened. Amazing!

Need to film this in higher frame rates. There are only a few frames of the plane per loop at 24fps. Also, It's good to see such an extreme design behaving so well outside of its peak environment, seems to soar pretty well on the up draft.

Beautiful plane!

Out freaking standing!

Very cool! What kind of improvement in critical mach are you seeing? Any issues with wave drag on that T tail? (it might need a body in front of the junction)

Impressive that the wing didn't snap in two.

Cool Spencer, great Job. Grüsse aus der Schweiz

No idea why I got this, but glad I did - great engineering

Yes fast for light winds can't wait for heavy wind version hope he sells them

Amazing - beautiful

It may not be as fast as some of the others but it sure looks more bad ass and faster with the swept wings.

He's created a monster... wow

Holy expletives Batman. That sucker is fast.

Love the sound

It was hard to see the glider but just barely. Could I have a streamer on it or smoke?

Une vidéo sans musique inutile et bruyante, rien que le bruit du vent. Super, bravo !

just amazing works

Wild that it's possible. How is it shaped? single layer of CF in a mold and foam core?

Yes sir more please!

Awesome plane and great place to fly! I've built quads that will do half that speed and i wouldn't stand anywhere near them at full throttle!!!

One of a kind for sure😊.

That was a great recording of your flight. Unfortunately, the gentleman spoke too quietly. And we never actually heard how fast you went.523?

Is there a making-of? Or more background info about this build?

Amazing !! Wonder if it can go supersonic ?

Incredible control by the pilot. One glimp of a movement and crash. Have you an G-Meter inside? FPV Camera will be an awesome rollercoaster.

in relation to 178 where is the place you are flying, i go through there all the time and i never see some of the stuff i see in your videos like the big green planted fields, in fact that whole valley below where you are flying looks way bigger than the valley where 178 runs through weldon although one part does kind of look like all the trees east of the lake by the kernville cutoff but i don't see any highways.......

Крутое место, в жизни бы не подумал что можно так сильно разогнать планер😯 👍

wow...... It must be really strong in the center section

Absolutely bonkers🥰

Ill bet those wings were incredibly bombproof, but still, some flex going on there...

Cool design!

wow! just wow!

Great, was it inspired by Apus apus - swift bird?

Amazing

I know nothing about this but after a while it looks like a blade of a giant invisible windmill. Are there similarities?

It Looked like exactly how the way swallow flies! 😊

Amazing!

Superb !!!

That's insane!

How did you power it? Can you do a video to show the engineering and where you have the motors because I can't see anything!

That’s insane 😮

Impressive! Sweeper wings flying by reminds me of swift (bird) wings. No coincidence, I'm sure. 🙂

Are these guys in any way connected to the Perlan project? At very high altitude the ability to exceed the speed of sound would be usefull I would have thought.

If I showed up to local slope with such a weapon, I would bring a security detail and everyone would believe I was testing for the military, lol.

Is this the first swept wing DS?

Wow!!!!👍👍👍👍🔥🔥🔥

Очень хороший планер, скорость сумасшедшая! 😊

That turn’s easily got to be 15-20 Gs, just amazing engineering

l been flying rc for 50 years and l would like to know more about this ultra high performance sport looks crazy fun.

Siiiiick. Is that, like, exploiting the boundary layer as a way to get upwind without losing energy? Sort of like "pumping" a swing? I want to try that.

How many y G is it pulling? Can it be scaled up ??

Beautiful design beautiful design I want 1❤

Superb, looks like a skinny B52

Love all RC toys but gliders - especially unpowered are Koolest AF !!!

plans for this beauty ?