American Inverse-Wing Interceptor: Republic XF-91 Thunderceptor
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- Опубликовано: 15 май 2023
- In this video, we discuss the XF-91 Thunderceptor, a post-WWII jet interceptor with a rather unique inverse tapered wings, meaning they were bigger at the wingtip. We discuss how jet aircraft and specifically, swept wing jet aircraft, came to be. We also discuss a rather common and troubling issue these early jet aircraft suffered from and how the XF-91 attempted to solve that through its unique wing design.
Side note, the name Thunderceptor keeps making me think of Action League Now! Who was your favorite character and why was it Meltman?
![NoCap - Maliboo [Official Music Video]](http://i.ytimg.com/vi/FUV7E0QyniU/mqdefault.jpg)
"Thunderceptor". I love the names of 50s American jets. "We don't just intercept targets, we THUNDERCEPT them!"
Republic loved them some thunder
A nicely explained reasoning for the shape. And an interesting peek at how development was moving so fast during the early jet age.
XF-91 was actually first jet to go supersonic in level flight…but had to use rocket boost to do it
I built a model of this in about 1991. Forgot about it then remembered it as an adult and couldn't find it because I couldn't remember what it was called. I started thinking I was remembering it wrong and the plane never existed. Thank you, I'm not crazy.
This is arguably the most detailed breakdown on the XF-91 I have seen. This design always intrigued me from an early age building model airplanes and eventually becomeing a pilot myself. This is a great trivia question generating A/C for sure.
I had heard tell if the “Saber Dance” but never knew why it happened. Thanks for filling in a hole in my aviation knowledge.
A clarification - Folks weren't thinking the term "sabre dance" in 1949 and solving the swept wing pitch problem. It came years later with the advent of the F-100 when it displayed the tragic out-of-control situation as shown in the clip.
He did not say the term "Sabre Dance" was being used in 1949. He said that was what the phenomenon came to be called. 5:09
@@scootergeorge7089 Words be tricky, huh? As he was beginning to point out the addressing of the wingtip stall at ~5:41, I felt that it needed clarification. He later used "....that issue in mind...", (a late '40s specific relationship in his dialogue) which, to me, caused some chronological confusion. Later, at ~7:35, this misappropriation occurs again. It doesn't spoil the video for me, the coverage of this unique airplane was quite good for the most part. I was deeply impressed with our whole aviation outlook as a child, even built the only plastic model of this airplane available at the time.
Aram Khachaturian should have gotten royalties on the term.
@@hagerty1952 What patent did he hold?
He was actually a classical composer who wrote "Saber Dance" as part of one his ballets. Here's a link. I know you've heard it probably hundreds of times:
ruclips.net/video/mUQHGpxrz-8/видео.html
It's got flippers!!! I agree on the Action League reference...well played, sir! Hope your allergies clear up.
The ability to alter the AOA on this early aircraft is fascinating. The USN carrier aircraft which could change the wing's angle of incidence for take off (sorry can't think of it) is the only other aircraft I am aware of. Leaving only the 'Mills' concept, flying tail being adopted across all transonic craft.
This is a fair explanation of this plane and how it's aerodynamic planform came to be. Thing is, I never once heard you mention the concept's reason for being - in fact, the inspiration for it's name: Thunderceptor. The U.S. Army Air Force had laid out specifications for an aircraft to contend with the anticipated threat of nuclear bomb-toting aircraft coming to wreak havoc upon the USA. In keeping with the course of aircraft design, it would certainly have to be jet powered. Trouble was, there were no jet engines that could propel an interceptor plane like the WWII rocket-thrusted Me163 had demonstrated. The proposal that resulted was the pairing of rocket motors and jet engines. Theoretically, such a plane would get airborn - fire off the rockets and ascend to get to the altitude of enemy formations.
The V tail wasn't just an aferthought. It had been one of several options from the very outset.
The kazoo modification was used on the Ju-87.
My first thought exactly, and maybe party poppers loaded with radar chaff.
Your channel is amazing for the size, I hope you never stop making these great videos. The world needs channels like yours for all the millions of channels that are just over super hyper saturated with bullshyt, meaningless videos and content. I swear RUclips now just gets worse and worse every week
The image you use to demonstrate the concept of exceeding Mach 1, is simply the moisture from the air gathering in level flight, along the boundary layers during transonic flight.
Thank you so much for your content.
I am relatively new to the channel but have binge watched, your entire catalog! Your videos are consistently interesting, well delivered and entertaining! Really appreciate the time and effort you put into each of these videos about aircraft, weapon design and the lesser known facts about historically significant events!
Keep up the great work!
Another perfect video. Never change!
Very good and very informative. Good job! Thank you!
It would have had great results with this wing design in combat too I imagine. The enemy pilots would have died laughing.
Love the video.Fine explanations.
Outstanding History Lesson. Well Done.
Get to feeling better soon.
One problem I see with that design is that, with the outer part of the wing wider, it would produce greater lift, and possess greater mass. Both would exert a greater moment, and hence, more stress, at the fuselage, the latter, during maneuvers, from the inertial force.
This was a good video. I always wondered why this aircraft had the wing shape it did.
I think that the builders really put the wings on backwards by accident and, rather than admit the mistake, were just all like "oh, yeah, we meant to do that". 😁
🎵 Fat winged planes, you make the rocking world go round. 🎵 Thanks!
I do love those wider wingtips.
very interesting video. good stuff.
3:42 i remember from my childhood around 1964 the grocery store had rubber band launch able small plastic glider toys , that British tailless jet was one i played with ! My intrest in planes ,jets , rockets all had roots in my early childhood and definitely fueled by tv shows like Thunderbird's and cartoons .
I've watched many of your videos, and I think they're great. Please keep them coming. I like that you address lesser-known events; and your editing, narration, and pacing are just right. Please keep them coming.
Well said
This video does not really explain the purpose of swept wings or the pitch up effect.
Swept wings do not reduce drag per se, they increase the speed at which compressibility creates a drag-increasing shock wave. If a straight wing airplane doesn't already approach its critical Mach number or drag divergence Mach number, just giving it swept wings of equivalent lift will not make it faster. (By the way, the wings of the Me-262 were not slightly swept to increase its speed, they were swept to rectify a problem with the center of gravity in same way sweeping the wings of the DC-3 did.)
All swept wing aircraft stall from the tip first, but they do not usually pitch up suddenly. Swept wings stall more gradually than straight wings, and the positive pitching moment tip stall imparts creates a lightening of the stick force required to hold the angle of attack, which usually remains controllable well into the stall. Uncontrollable pitch up usually occurs when a change in downwash affecting the horizontal tail prevents it from controlling the pitching moment. Pitch up instability occurs at very high angles of attack that are typically beyond the usable range.
A sudden pitch up did not cause the famous Sabre Dance crash. The real problem was insufficient directional stability that allowed excessive sideslip to develop, which in conjunction with high angle of attack created uncontrollable rolling moments. If you watch the video, you can see the AOA, while high, remains controlled until the airplane begins to yaw and roll. The solution to the weak stability was to increase the size of the vertical stabilizer, not change the size of the horizontal tail or angle of the wings.
Yes. I'd known that the cure for the F-100 "dance" was to enlarge the vertical stab surface and was surprised he didn't go into that detail in the video.
@@whalesong999 He didn't go into that detail because he doesn't really understand the Sabre Dance and thinks it as was about pitch-up when it was really about insufficient directional stability. The swept wing did contribute to the Sabre dance, but the primary characteristic at play was its roll due to yaw rather than tip stall.
The F-104 had a pitch-up issue at very high angles of attack, and it had a straight wing. The pitch-up was due to downwash over the tail. The solution was a to keep it out of that extreme AOA range with a warning system and a stick pusher.
And I still wonder why the rocket plane breaking the sound barrier had straight wings?
"Yes Doctor, he's right over here." said the nurse as she led the Air Force psychiatrist towards the vacant office that was hastily turned into an ad-hoc holding area for this questionably mental patient who was brought to the clinic. As they walked she filled the Major in on the particulars "The Gentlemen in our custody was brought here after he'd finished up his guest speaker lesson that he was giving to the aeronautics program at our local college. The resident professor and students became worried when at the end he started spouting all manner of wild and I dare say crazy things that even I know don't belong on airplanes." =P
The term "Sabre Dance" was unique to the F-100. The early versions had a shorter vertical stabilizer. There was not enough lateral stability at some points in the flight envelope. The solution was to lengthen to vertical stabilizer in the F-100C.
Coupled with that, in the accident video, the engine was not capable of generating enough thrust to fly out of the coffin corner. It can be seen that the engine was in full afterburner but lack of thrust and yaw instability cost the the pilot his life.
ruclips.net/video/Q2qqKwndFW0/видео.html
12:11 Now that's some kinda wing fences, whew!
Thanks Man
12:12 ,you forgot to mention leading edge "saw cut" notches, does the same job as a wing fence at much lower weight and size (the EE lightning, F8 & F4 all had them and prob a lot of others)
Convair F-106 Delt Dart also had the notches.
confetti rockets....kazoos in the engines.
made me sub!
Is the tumbnail an Action League Now reference?
If the tail on the second aircraft as you said "literaly disintegrated", I presume this did not happen while on the ground; so how did the aircraft survive to get a V tail??
Wikipedia said the engine failure occurred 90 seconds into that flight, maybe the pilot got it on the ground before the tail burned off.
Many test sites were dry lake beds so you could land just about anywhere.
9:16 Its not unique for landing gear to fold outward, (the EE Lightning did it) ,its just unusual.
The wings on that plane are somewhat similar, just with a constant chord.
great thanks
You put it as if swept wings had generally lower drag. Not the case. The advantage is mainly there in the transsonic range.
You definitely don't want a lot of sweep in the incompressible range of aerodynamics.
11:31 Given that the V-tail wasn't incorporated into any of the 1950s US fighter designs, I would assume it was found to offer no advantages.
tiny, tiny rudder! At low speeds I can't imagine that rudder having much effect when you need it most.
I really enjoyed this episode but what was that b2 biplane?
The S.E.5a
Allergies, the fun for everyone, share it! Oh wait, you can´t... Well, get better soon!
Seriously though, that inverse wing looks SO goofy, as if some engineers had made a serious mistake and put the wing on the plane the wrong way around.
That's 1 of those it's so weird it's beautiful planes to me...I've always liked it.🤓
Thought that the Sabre Dance was a one time event...
What would they think of the Canard aircraft?
The Germans were more smart and tried to turning the wings forward, to higher airspeed at the roots of the wings, for an experimental bomber, with I think to remember had 6 jet engines?
What airplane is that from timestamp 1:53 to 2:20 please it's the coolest biplane I've ever seen
Winglet-tips probably help too.
Your explanation of why an inverse wing would prevent the pitch-up problem seems contradictory to your description of why pitch up occurs.
Never before have i wanted to tear my eyes out on viewing any aircraft😮😮 but Wtactual f?😢
looks like someone didnt follow the directions and glued the wings on backwards.
4:14 *Laughs in F-104 Starfighter*
I thought that aircraft was a joke when I was a kid.
THOSE WINGS REMIND ME OF BELL BOTTOM JEANS
That's a picture of one of J W Dunne's flying wings at the 2:00ish mark (it looks like the one trialled by the US Army. The true inventor of the powered flying wing and nit those Horten brothers who always seem to get the crefut.
I'd rather be able to fly like thunder than have the power to melt.
Bellbottoms!
What did the fuselage say to the stalled wing?
"Do you even lift?"
Huh-huh.
comparing this thing with F104 or F4.... jeeez.
Lots of misleading statements regarding wing sweep and tip stall.
"clown horns"
Gumbieceptor.
Please include metric measurements I’m getting sick of trying to do the conversion in my head
Grown-up units.
I'm the other way round, finding metric irritating. I prefer realworld measurements - inches, feet, pounds, miles, etc.
'murica!!
PLEASE stop repeating the Me262 swept wing myth. The BMW 003 engines ended up being heavier than anticipated and thus the wings were angled slightly back to maintain the CoG, just like the earlier Douglas DC3, which even the most brain dead of "aviation" RUclipsrs aren't daft enough to claim is for performance. This fact about the Me262 is even listed in the Wikipedia page for goodness sake, but yet here we are again.
Good video
but for gods sake, get to the point
The point of the video is that your mama.....was a camel
For God's sake, please learn to use punctuation.
It is your friend and helps get your point across without losing the credibility you are attempting to convey.
@@gregoryfuller1136 good point
God, that's an ugly aircraft! Good video, though. Thanks.
It didn't so much take off but was repelled by the ground.
I'd go along with that! What do aerodynamicists know anyway?
Interesting content, uninteresting narrator. I suggest you bring snacks for this video.
Computer generated voice.... So anoying!!
The Sabre Dance was one accident where the pilot got behind the power curve in a F-100 Super Sabre ferry flight.. Swept wing stall characteristics are not called “Sabre dance”. Well documented and all aviation books. The F-91 wasn’t a Sabre ! it was built by republic so therefore it could not do a “Sabre dance” . It’s design was to get rid of the swept wing tip stall characteristic just like slats, washout and vortex generators, suction (boundary layer controls) and a few other ideas. Good info but the wrong use of the words saber dance.
Cheers