Spencer testing Transonic Sweeper

This is a video of Spencer Lisenby test flying his new Swept Wing Transonic at Weldon with wind speed ranging only between 25 to 32 mph. This model has a lighter layup for test purposes, and handled the lighter slope conditions with speed and grace. Wingspan is 130 inches square to fuse with a ready-to-fly weight of 186 oz (5200 grams).
More info here: www.rcgroups.com/forums/showt...

[@goldendredger]

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!

[@cabanford]

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 💣🚀)

[@silentblackhole]

Control it from a bunker, or at least the boot of the car!

[@dannydecamp6846]

This is so wild, I showed my dad this (retired fighter pilot/ commercial pilot) and he didn’t even believe this. Where can I find more info about this? Is there a name for this sport/type of gliding??

[@cabanford]

@@dannydecamp6846 it's called DS (for Dynamic Soaring). Amazing stuff, well worth falling into a rabbit hole for.

[@weatheranddarkness]

@@dannydecamp6846 the pilot here did a presentation about the physics here: kzbin.info/www/bejne/pKeaXoyDadyhpZo

[@caturlifelive]

@@cabanford thank you

[@arwo1143]

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

[@ChrisMisMYhandle]

no props, just wind

[@nateisright]

😂“Props” = proper respect , not propeller

[@ChrisMisMYhandle]

@@nateisright that's what makes it a joke 😊

[@ernie5229]

The odds of one plane decapitating 3 people are zero. Even if lined up correctly, it's only a 186 oz plane. After the first decapitation there wouldn't be enough energy for the other two. Chill, bruv.

[@dsdy1205]

@@ernie5229 XD On a side note I watched a video where they crashed one of these things into the hillside they were standing on, there was a very audible ground-shaking THUMP, akin to a car crash.

[@isaiahhiggins]

the wing loading must be incredible

[@jackroutledge352]

It's really light, so might not be very much. If the wing loading was high it wouldn't be very efficient, and so probably wouldn't pick up as much speed.

[@isaiahhiggins]

@@jackroutledge352 I prove once again that I don't know what I'm talking about 🤐I meant the G-loading due to those violent, high speed loops. I guess wing stress would be more accurate.

[@lr21643]

@@jackroutledge352 High wing loadings don't mean low efficiency, they mean flying faster at the same angle of attack. At least until you get into the transonic region, anyway. Viscosity can be less important as speed and size go up, so an aircraft may have a slightly better L/D as it gets heavier. This is especially true of models.

[@UltraVioletYS]

@@isaiahhiggins Based on 553km/h and ~4 seconds per loop, the average acceleration comes out to 24.5G for an apparent weight of 127kg. Kind of wild. You could work out the wing loading from the 130" wingspan and the photo at the beginning

[@TheHarryMann]

@@jackroutledge352completely opposite to the aeronautical facts of design. You need high wing loading to achieve high speeds, or rather, high wing loading mitigates towards high speed and vice versa

[@needmoreboost6369]

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!

[@marielizysurourcq]

You are right. I went crazy on drones and then planes, but I have to say that nothing beats watching high speed gliders. It's very close to surfing big ocean waves in a way.

[@needmoreboost6369]

@@marielizysurourcq surfing is a pretty good comparison! in part what I meant is,it’s just pure! My gliders would clap their wing tips like an applause to the surviving plane’s of this type of slope and speed as they went down!

[@anotherguy9402]

Then you haven't seen rc racing planes

[@Maximum_777]

Have you seen this video of a 548mph sail plane? They had significantly higher winds there. kzbin.info/www/bejne/apapdZKNn5uXns0si=lGyxR9D-qrGl_fb6

[@davidsullivan8236]

This is amazing it could fly forever imagine if was scaled up

[@gisall8205]

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

[@kamoteph273]

please no, you dont want that thing ending up stucked at someone's forehead😂

[@kamoteph273]

@@Bebtelovimab 🤣🤣🤣

[@alexcrisara4902]

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!

[@mattridgway8807]

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

[@anthonyb5279]

Thats because its not real

[@PacificAirwave144]

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

[@MelindaGreen]

I prefer seeing it from a safely remote location. I'd be too afraid of losing my head if he sneezes!

[@Keatwonobe]

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!

[@mwales2112]

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

[@Adeptus_Artes]

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.

[@pcka12]

Gliders are not 'powered by the wind' although they may 'translate' moving currents of air into 'lift'!

[@erickborling1302]

Yes gliders are always descending relative to the wind.

[@maxvanN]

gliders aren't powered by the wind, they just move through the wind. They are powered by any uplift caused by thermal differences causing convection. This is all caused by the sun so basically it is solar powered.

[@caturlifelive]

Agreed, awesome

[@TylerKaraszewski]

@@pcka12 This is an interesting semantic discussion. Are sailboats powered by the wind? ;) I think in either case it depends on what you mean by "powered". Both generate lift from the difference in the movement of the air relative to the surface. In dead still air, both eventually drift to a stop.

[@sf1203]

Amazing. Looks like the test went pretty dang well.

[@bgdexter]

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

[@Part_121]

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

[@mikebeacom4883]

Like an anorexic B-52

[@cabanford]

@@mikebeacom4883 Hahaha 🤣 (my dad was a Navigator in BUFFs from the mid 60s to the early 80s).

[@txflyguy0076]

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

[@bobjohnson7207]

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

[@Itsjustme-Justme]

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.

[@Lanzbik]

And also make sure it’s a full flying elevator so the shockwave caused by the leading edge of the tailplane doesn’t shroud the elevator

[@GlideYNRG]

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.

[@mikeadams7832]

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

[@sbkenn1]

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.

[@stacyp4534]

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

[@paulbrouyere1735]

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

[@ZdrytchX]

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

[@Avianthro]

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!

[@johnbasiglone1219]

How fast is it going? Transonic would need to be around 720 mph and a little less depending on the altitude.

[@Cyberdactyl]

@@johnbasiglone1219 My wild guess is around 238 mph. I am taking a wild guess he's doing 400 foot diameter loops. That's 1257 feet per loop. I timed his loop at around 3.6 seconds. That into 1257 is 349 feet per second or 238 mph

[@joewoodchuck3824]

Awesome plane, fantastic flying spot.

[@eklhaft4531]

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

[@gdutfulkbhh7537]

Congratulations. That is wonderful.

[@RichardBronosky]

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.

[@user-od3vl7he9z]

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!

[@TRabbit1970]

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

[@fredtedstedman]

so beautiful , has the sweep of a Stratojet !

[@aaindtharivalan8720]

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

[@bmwjoon]

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

[@skyak4493]

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.

[@claudevieaul1465]

This is astounding. I've only recently discovered dynamic soaring even existed, here on KZbin - 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....

[@lr21643]

If your wind turbine is attached to the ground, you don't need to use dynamic soaring. The tips of some wind turbines may go at 10 times the wind speed, which is probably not so different than we're seeing here.

[@dougaltolan3017]

A tethered kite generator would be the closest, but as lr says above if you have any ground attachment, you don't need dynamic soaring to extract power.

[@normg2242]

Funny you should say that. As I was watching this, I wondered if this principle couldn't be applied to wind mills or turbines ...!

[@smile768]

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

[@ck2503]

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

[@hal_aetus]

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

[@tstodgell]

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)

[@NickAbbot.]

A+ for the cameraman.

[@weatheranddarkness]

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.

[@durden91tyler]

Great idea, I'd say it's worth sacrificing resolution down to like 720 if it meant 120fps so it was clear and smooth

[@linecraftman3907]

it's mostly youtube compression of the video

[@WhatDadIsUpTo]

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

[@Imba-gt7qi]

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.

[@GryphonArmorer]

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

[@knutbergan]

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

[@johnsnider9780]

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

[@haeuslerpatrick]

Cool Spencer, great Job. Grüsse aus der Schweiz

[@bugdozer]

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

[@antoinelemaire9453]

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

[@williamchamberlain2263]

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

[@PlasmaChannel]

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

[@michaelwhinnery164]

Impressive that the wing didn't snap in two.

[@atvheads]

No batteries, and no engine. that's why i guess.

[@weatheranddarkness]

Part of the reason is that most of the mass is evenly distributed across the wings and so is well supported under the G loads, the fuselage mass is a less acute stress riser than in some other aircraft.

[@ccm_priv]

it needs batteries for steering bud@@atvheads

[@klesmer]

Never thought I would see a sailplane fly that fast. Fantastic. Where was this video taken? Beautiful country.

[@toolbaggers]

The fastest RC planes are sailplanes.

[@neilbarclay7070]

Record for Dynamic Soaring is like 560mph these are full on carbon and kevlar gliders. Balsa,foam, fiberglass just doesn't cut it at these speeds and that's why DS has only come out in recent years of model flying.

[@bryanlallen]

Weldon, east of Lake Isabella.

[@treyschwartz3966]

@@bryanlallen I recognized the location because I windsurf on Lake Isabella and I’ve ridden those roads on the bike. I’ve been thinking of getting an RC glider to slope soar there.

[@alexprost7505]

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

[@farklek]

Beautiful plane!

[@28th_St_Air]

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

[@shiningirisheyes]

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

[@avpr1c]

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!!!

[@Cheelex333]

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

[@abruptlyblunt]

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.......

[@engkosperkasa2027]

It Looked like exactly how the way swallow flies! 😊

[@coma13794]

African or European?

[@user-ox4zi6gq6f]

Очень хороший планер, скорость сумасшедшая! 😊

[@ScrubsIsee]

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

[@dracoQuest]

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

[@stephenallen4374]

Beautiful design beautiful design I want 1❤

[@DanFrederiksen]

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

[@LWJCarroll]

I thought dynamic slope soaring was on the downwind side of the slope up into the top of the over flow. Did I have my wires crossed all these years. Laurie NZ. 😊

[@michaelcuthbert6956]

Looks like the launch was into the wind, but then moved to the downwind slope (around the 53 second mark) for the DS testing.

[@toolbaggers]

Things work in revere in the southern hemisphere.

[@dougaltolan3017]

Dynamic soaring and slope soaring are different things...

[@valderja]

Cool design!

[@GabrielDeVault]

Out freaking standing!

[@dmcwlk]

Amazing - beautiful

[@dnacannotchange]

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

[@Neptune730]

Holy expletives Batman. That sucker is fast.

[@AlexDiesTrying]

He's created a monster... wow

[@jefdamen2977]

Love the sound

[@fowrunnah]

One of a kind for sure😊.

[@wizzfred2]

just amazing works

[@alistairclark6814]

Yes sir more please!

[@harfenspieler]

The kinetic energy at full speed is around 20 kilojoules, and it takes a split second from pilot error to impact. Personally I'd be hiding behind those rocks…

[@CGreciful]

I was going to say a blast shield! Pilot error, control surface failure, electronics failure....

[@Xsiondu]

Transonic flutter magic.

[@ForgottenMan2009]

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.

[@boogie153]

Amazing !! Wonder if it can go supersonic ?

[@user-ot7kp4vj7u]

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

[@michaelogden5958]

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

[@r0cketplumber]

248 m/s and 5.2 kg is about 160,000 J kinetic energy. Typical muzzle energy for a handgun round at a similar speed is around 500 J. I would rather watch that fly from behind some significant armor.

[@mrt1957]

a grain of sand at 556.997 miles per hour would be a concern. This flying razor is terrifying and fascination.

[@keppscrossing]

Several years ago I calculated the kinetic energy of one of my friends planes when he was radared at 284 mph with an 8 1/2 pound plane. It was about 26,000 foot pounds of force, or double that of a military 50 caliber round. Previously we had been using our trucks to hide behind, but realized that only the engine block would protect us. That plane would probably go right through the sheet-metal of a pick up truck. Another time I watched a plane penetrate 18 inches into very rocky soil after being retarded about 150 mph before the wing broke. That plane was not designed for dynamic soaring.

[@aga080]

lol you could not pay me enough to stand near that thing going transonic. one hiccup the crowd is sliced in half. you guys should build a plexiglass structure to stand behind (not even sure what that will do)

[@LateralThinkerer]

This - It's a flying straight razor. A chain link fence would do it...I hope!

[@toolbaggers]

I'd be spectating behind the trucks!

[@toolbaggers]

@@LateralThinkerer More like flying 2 long swords

[@InfoWithheld]

What speeds? With wind-noise and no added text overlays, all I hear is (muffle)47, (muffle 56) etc.

[@doggylover1958]

About 556mph.

[@InfoWithheld]

@@doggylover1958 damn! Despite "transonic" in the title... i was expecting to hear 247, or at most 347. Not 500+.

[@doggylover1958]

@@InfoWithheld The record set in Feb this year was 564 mph, I don’t know how they can see the plane at those speeds. kzbin.info/www/bejne/fXS5fGataql7mM0feature=shared

[@NonEuclideanTacoCannon]

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.

[@dougaltolan3017]

Yeah, Nahh... Sail boats can go faster than wind speed by using the keel to maintain aerofoil attack angle. Planes don't have the benefit of water to do that. What they can do (is doing here) is use the momentum of the plane. Maximum energy is imparted at the upwind part of the turn, when it's flying across the wind. Sure, at the downwind section it dips below the wind into the turbulent zone, but that does allow it to return upwind for another boost. It's a mistake to think that it gets speed by ducking out of the wind, sneaking back upwind and getting a tailwind push. It flies much faster than the wind, so that can't be the mechanism. Note that this is done on the leeward side of the hill, whereas slope soaring is done on the upwind side where the air is rising.

[@user-dq5lu6nx3y]

Look up dynamic soaring to get the physics.

[@kazarbizar7892]

Absolutely bonkers🥰

[@swoondrones]

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!

[@dougaltolan3017]

No engines, it's a glider (sail plane)

[@petr0news]

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

[@critical_always]

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

[@mpojr]

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

[@RothRothschild-xj3nx]

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

[@Yuki_Ika7]

Amazing!

[@evanleebodies]

Superb, looks like a skinny B52

[@QDStrength]

Is this the first swept wing DS?

[@coma13794]

well, of COURSE Spencer built a swept wing transonic glider. ##$##@#@#@ why did I move from California to NJ!?! Congrats to all involved, can't wait to see the results with the fully loaded model on a big day.

[@dorsetdumpling5387]

..when a B52 dreams of losing weight and becoming a glider…..!

[@toolbaggers]

BUFF doesn't want to be an fat, angry bird.

[@ioannisbatas1614]

Superb !!!

[@po1ly414]

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

[@nonotrasher]

about 80

[@MrSteve2714740]

More like between 75 and 90 G. Insanity isn’t it.?

[@lr21643]

@@MrSteve2714740 Does that mean the ride is bumpy or that I'm over-estimating the turning radius?

[@MrSteve2714740]

Wouldn’t say it’s bumpy. And at “normal” sort of speeds the circuit is large. But speeds like this it’s obviously going to be a tight turn. The pilot flying really knows his stuff. Not many RC pilots could even contemplate the difficulty flying at these sort of speeds. I’ve flown fast slope soarers in my 40yr area of RC planes but I’m no where confident enough to enter into the dynamic zone. These gliders are incredibly fast and on another level. Big respect to the dynamic lads in my opinion.