Prop powered Boeing 727 amazing sound on low level flypast air-to-air
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- Опубликовано: 30 янв 2018
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Prop powered 727 from August 20, 1984. It was called the 7J7 with an unducted fan. Boeing dropped the idea. Watch more great footage like this at www.jetflix.tv
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Приколы
The reason you don't see these engines is because they figured out how to do the same thing but with ducted fans. The latest ultra-high bypass geared ducted jet engines have the same fuel efficiency but without the noise because of being ducted. Basically this technology did become implemented, but was first improved.
Thank you I was wondering this!
This was done in the 80s, when turbo fan engines were already common. your comment doesn't make sense to me.
Edit: I've had multiple replies saying I'm an idiot for typing this and that this engine, built in the 80s, led to the invention of the high bypass turbo fan. I understand that the bypass ratio has increased over the years, but the high bypass turbo fan was well into it's existence during this time period (1985). The original 747 had high bypass turbo fans back in 1966 and the cf6 high bypass in 1971!!!
@@SMFFL100 Turbofans in the 80s are much different than today. The bypass ratios are almost 4 times now what they were in the 80s. Furthermore we have geared turbofans now, which use gears to increase turbofan speeds relative to the speed of the jet engines, provided even more bypass thrust. A lot of this outcome was similar to what these props were intending to do, with better overall results. Improving the turbofans of the 80s turned out better than what this design offered, but a similar end result.
so the latest engines have the efficiency as the one from 1992?
@@nutzeeer pretty much. All technology thats released is about 20 years behind prototype development. It takes about 20 years for a prototype idea to be refined and mass produced, give or take. And sometimes that prototype is dismissed as the wrong direction and instead slow gradual improvements to existing designs get better enough that the prototype design is unnecessary. Right now there are prototypes like this jet engine that are even more efficient than the existing mass produced ones, and we wont see their implementation for another 20 years.
Sounds like a Stuka in a vertical dive aiming to bomb something.
Come on. Throw these poor people a bone or something! Toss the Geared Turbofan into a time machine and send it back, along with a couple of fashion items from present day, and problem solved!
Definitely sounds like a Stuka LMAO. Break out the Xanax when you hear one of those fly by.
You just HAD to mention The War
Actually I thought it sounded like a loud bumblebee. It wasn't that loud but it was more of a whine than a roar like a typical jet engine but not any more obnoxious.
love it ... now why not put a duct around it?
Man, I can’t wait for that 7J7 to hit the market! Sounds incredible!
When did they expect it? ‘92?
2092?
Ken Badziak I think they were working on the 757/767 airplanes. I suspect the spinning scimitars rotating at high speeds could not be mounted under an airplane wing.
Mitchell Brown doing some research, it looks like they were developing a 737 MAX4, and yeah. They were having enough issues already. Decided to reinvest that money instead into a state-of-the-art overhead panel instead.
I mean, 1950’s SOTA, but still...
The 757 was already flying during the production of this video. Looks like the 7J7 was a guppified 727.
en.m.wikipedia.org/wiki/Boeing_7J7
Yes the sound was incredible, LOUD that is... It simply made to much noise, that is why we don`t have engines like this on airplanes now.
Rondo Cat except maybe the Piaggio...that’s one strange sounding airplane!
Due in 1992??? Oh boy i cant wait to see it in production!
Motrhead69 or the americans if Trump continues with his foreign politics with Russia, China etc...
@@necu9365 Huh?
Bra 0711 I got news for you, it was all a hoax you moron
@Bra 0711 OMG he'll start WW3 with N.Korea too... oh wait!
Go troll else where dumbass
@A R yeah youre correct
Props to GE for getting this to market so quickly.
That's some heavy sarcasm lol.
@debandgary Wi on the contrary, we do. I have a Kia Niro Plug in hybrid. I am getting 137 right now
@@jmattos4290 I have a 1970 Plymouth Road Runner, w/ a 383 C.U. engine that will light the tires up and look good every time. The only thing it won't pass is a gas station.
@@jmattos4290 But... OP was talking about miles per gallon, not horsepower...
debandgary Wi airline companies are always trying to reduce fuel consumption. Burning fuel is burning money.
Man this thing flying over a city would give so many WW2 vets ptsd flashbacks
If they mass produced these, all the Europeans would be ducking in cover whenever one flew by.
Most of the people who were subjected to that noise are now dead.
it flew over the old persons home, and WWII Started back up...
Jake Kennedy just like the end result
Americans too
@@LukeRen-rl4yv 😂
That was a disaster. It was very loud and the shock waves beat the hell out of the fuselage a few inches away. How do I know. I worked the airplane which was a real POS from Peru as I recall. They had some hotshot that talked a good battel go down and "Survey" the airplane. We spent a ton of money just to get it airworthy. Minor things like a huge skin crack under the right forward inbd wing fairing. A lost cause from day one as most of the components had to be removed and replaced. I believe that Boeing in their wisdom made the guy a manager. The Peter principle in full effect.
Excellent information. Thanks.
They should have built a case around the blades to reduce the noise and shock to the fueselage. No wait..
Still better than any 737-200 of the era. They were all cracked and patched. Even before lap joints.
@@azspotfree yeah, they should've done that for creating airplane engine since putting a case outside will also encapsulate the propeller and able to make more power
Hey, wait a minute...
@@arvin6606 Arvin, you and azspotfree aren't thinking it through.
Instead of contra rotating props they should have just put more blades that were thinner.
The shroud is a good idea.
It could be an Ultra High Bypass Shrouded Jet Engine.
Man... the 90s are gonna be wild!!
I was a flight test engineer on this project for McDonnell Douglas. We used an MD80 and tested it at Edward's Airforce base.
@beentga 757 yeah, like that is something one dreams about.
airandspace.si.edu/collection-objects/mcdonnell-douglas-md-91x-md-80-uhb-refit-proposal-engines-allison-model-578-dx-0
beentga 757 You're gay
markleyg what are you doing now? Still flying?
@@1compaqedr8 I wasn't the pilot, I was a data system engineer. We designed and maintained the sensors and computers for each test flight. I've been out of engineering now for over 15 years. I was allowed to fly on the test flights but usually didn't because it was pretty boring just sitting in the back of a windowless plane staring at a computer screen.
@@1compaqedr8 I wasn't the pilot, I was a data system engineer. We designed and maintained the sensors and computers for the test flights. Been out of engineering for 15 years. I was allowed to be on the test flights but usually didn't because it was rather boring just sitting in a windowless plane staring at the computer screen. One exciting thing on this project was its first flight. I was directly behind the plane on takeoff. The UHB was only on the port side with standard engine on starboard. The moment it left the ground the port wing took a quick dip and just missed hitting the ground. Have a lot of respect for those test pilots and how fast they can recover. Got video of it somewhere.
As there are no known sound recordings of the Thunderscreech, this is the closest we'll probably ever get, great footage! 👌
This does not even come close to the amount of DB’s the Thunderscreech would’ve produced
@@GrummanTestPilot I fully agree that the tiny speaker in my mobile phone couldn’t produce the same level of decibels as the Thunderscreech.
Goes to show that what might be classified as R&D failures can still be examples of awesome engineering!
It wasn't really a failure.... It just never took hold because fuel prices never went high enough to make this profitable
So disappointed those udf engines never caught on. They look and sound so cool.
Scott Major they DID catch on... all modern jet engines are derivatives of this technology- they simply eliminated the counterrotating fan and enclosed a huge fan with a lot more blades in a huge duct which improved its efficiency by 20%. Modern jet engines with the huge cowls are actually super high bypass ducted turbofans...
At the time this experiment was made, jet engines were entirely compressor/combustion driven by high speed jet exhaust alone. Noisy and fuel inefficient.
My favorite one now, is the Geared Turbofan on the A320 NEO. It is so much like this, but has a huge fan disk, that is geared down. It is ducted, of course.
@@christopherpardell4418 Bypass fanjets had been around in commercial jets since the late 50's. The P&W JT3 on the B 707 was one of the first. GE produced an aft fan engine for the Convair CV 880 and 990. Douglas was also using the P&W's and moved onto later GE designs. No B 727 flew with straight turbojets either as they came with JT 8D fanjets and the JT9 first flew in '68 with the B 747. These UDF projects never did catch on as the ducted high bypass fanjets gre in size and power which offered more especially for the more common low wing mounting of jet engines on aircraft.
@@christopherpardell4418 The UDF was tested in the '80s, high bypass turbo fans existed back then. The UDF was an attempt to achieve jet speeds with turboprop efficiency, without the weight of reduction gear . The reason that it was a dead end then was that the sound levels exceeded environmental limits.
I would say the biggest factor was noise. As others replied, high bypass engines came along that are much quieter and are just more efficient. I suspect there was some safety questions as well with respect to liberating blades. The high bypass engine are supposed to contain liberated fan blades. There is no containing those fan blades and there are more of them than standard propeller engines. The ducted jet engines are safer with respect to containing the fan blade. Much less risk to the aircraft and the other engine.
The technical data for the GE36 was sold to Cuisinart in '93.
Lmfao what
That'd make a big fuckin blender
Good one!
Beat those eggs. Lol make an omelette for 5,000 people in 10 seconds
Underrated comment
Almost all modern jets are now bypass fan engines. they just changed the design and covered the props
that's a compressor at the front end though. not a thrust device. but similar i suppose. they don't really explain much about how this works on the inside. top secret i suppose at the time
@@dayspoiler4608 .... the front end is a compressor for the jet engine, AND a thrust device. it blows air into the jet engine as well as around it.
The counter rotating idea was never continued however.
They use fixed vanes instead to help straighten airflow.
@@1971merlin Russian/Ukrainian airplanes (aircrafts and helicopters) use common counter rotative propellers size the 50' up today with the Ivchenko progress D27 (Antonov AN70), and Safran engines work sinze 2017 on a a similar engine (Open Rotor)...
At 1:27 that thing sounds like an old WWII fighter.
Uh no it doesn't. It sounds like every turbo prop I've ever heard which certainly never existed in WWII.
Charley Zimmer I think you are referring to the siren the Nazis used on their bombers in order to strike fear into their enemy...I’m sure I’ll be corrected, but I believe it was called the Stuktka ...or something like that
@@Miatacrosser Like the others said, it sound like the siren of that dive bomber the Germans had.
@@greenidguy9292 *Ju 88 and Ju 87* Stuka *had them*
@Valami Izé yeah that's it
While we aviation heads love that sound the public doesn’t. Inability to solve the noise problems, among other issues, put an end to that project.
Meanwhile the Thunderscreech design team is uncharacteristically silent...
@@eurogryphon dont forget about the TU-95 it's propellers are loud enough for submarines to hear it on thier sonars but not so wierd when the propellers are breaking the sound barrier
What's the problem? Everyone knows it's anti-American to not want huge quantities of unnecessary noise.
@@jsmariani4180 Yeah that's why we take the mufflers off of cars
Other issues yes of course, such as not being able to mount them under a wing for fear of a blade failure piercing the fuel cell in the wing or piercing the passenger cabin. Stupid idea from the beginning.
I remember seeing this at the Farnborough international airshow.. sounded fantastic
I remember reading about this in some design magazines back in the day. These unducted fan turboprops were a response to the big increase in fuel prices in the '70s and '80s. I recall that the noise they made (while cool) was not well received by potential passengers and was harder to muffle or dampen out than the smoother high pitch whine of jets. I suspect that the exposed high speed multiblade fans were more of a worry to potential passengers than the invisible though much higher speed turbine parts of ordinary jet engines. Plus people had rapidly become to equate jet engines with modernity and anything with a propellor as old-fashioned.
The big increase in 1970's MONEY PRINTING. The oil price hike was just one by-product.
Jet engines have now been been obsoleted by the 21st Century internal combustion engine, which is considerably lighter, more powerful, more fuel efficient, and much cheaper to build and maintain.
@Bhum Brahmavira ducted fans are actually infact better anyways
@@RayleighCriterion Explain? what engine could be used to replace gas turbines?
I think I remember hearing that the reason they were so noisy is that the exposed blade tips spin so fast that they actually created a succession of small sonic-booms.
A sky full of aircraft powered by these engines and you'd think it was a bombing raid
The speed at which the GE 7J7 juliennes french fries is incredible. I have one in my kitchen.
I wondered my my local takeaway has a jet engine in the carpark out the back. This must be what they're up to.
I guess it didn’t “take off.”
I’ll see myself out. 🤦♂️
Damnit
I just made this joke too
The idea was pretty plane so it isn't a surprise. The engines look pretty fly tho.
Gausts
LOL
You should just for using that emoji. Emojis are for bored housewives, be a man.
@@gausts Agreed, they definitely deserve some props.
Nice video Boeing 727 👍🏼🛩
Now we just use high bypass ducted fans. The extra bonus of ducted fans is that the shroud is made to contain the blades if they were to break. It works somewhat well. A fan blade in the fuselage would certainly be life threatening.
Man the past we’re the good ol days
As an addition, the prop fan itself was manufactured by Hamilton Standard (now part of Collins Aerospace). Hamilton had been a premier manufacturer of aircraft propellers since the dawn of flight.
Actually , although it is now called Collins aerospace it is still a division of United Technologies Aerospace. Formerly Hanilton Sunstrand , formerly Hamilton Standard...makers of propellers since the dawn of aviation.
I was working at Hamilton as a calibration tech at the time and remember them coming through the shop. There was a lot of excitement because it seemed like we were going to have enough work til retirement.... sad they didn't pan out but they sure looked cool....
@@mikepoulin3020 I was there from 1978 - 1999 and 2008 - 2011. Used to be a great place for a career.
@@BELCAN57 Steve Pitaro?
If you put the props in front and cover them all around,you have tomorrow turbofans
not really
@@SevenCostanza r/whoooosh
No. They were heavily spiraled.
@@IntelTV No woosh the op's comment is wrong r/physics
They were already present on the 747 amongst others - turbofans
I heard one of these warming up on the tarmac, it was extremely loud and high pitched. Like metal on metal spinning fast and grinding hard sound.
but then GE whipped out _the beast_ the GE90
I used to work on the GE CF6 80C2 in engine overhaul at QANTAS. Fantastic engine. We used to overhaul the PW JT9D 7R4 and RR RB211 524G's as well. GE90 is the big girl nowadays. The RR Trent 900 less so. All our engines are overhauled offshore now. Sad loss
The fan blades from this engine were the inspiration for the GE90 fan blades. Much was learned from this experiment. Composite blades with a Titanium leading edge.
That and Rolls Royces terrible failure with pure composite blades on the RB211.
a n i m e
n
i
m
e
Or should *We* say the GE9X? 😏
I've heard many counter rotating prop engine planes race at the Reno Air Races, and they are incredibly loud! I remember quite a few issues with them blowing seals, and gears, and calling Mayday! I don't recall what plane it was, but it had a single counter rotating prop engine with the main shaft that appeared to be at least 8 or 10 feet out from the nose of the plane. They said it was being tested to be the first prop plane to break the sound barrier. I guess that never happened.
I followed these very closely during the testing phase. Riding an Air Force C-130 showed me how loud the fans could resonate inside the cabin. When I learned how a single UDF created similar sound problems, it was no surprise to me that the project took a different direction. The turbofans that ultimately replaced turbojets, also were noisy and the 727 didn't have effective sound barriers, so it was decided instead to hang them off the wings.
I never knew that was a thing. Sounded badass.
Like one of the comments said below: Instead of a un-ducted propeller, people figured out that you could achieve a similar amount of fuel efficiency by increasing the bypass ratio of current ducted turbofans. Which lead to truly massive engines like those on the 777x. But counter rotating high bypass fans only exist in military transport aircraft and as far as I know, no civilian turbofan aircraft use contra rotating fans.
The unducted fan never panned-out, but Jim Johnson still does color for the Fighting Vikings of Western Washington University.
Quay Rude what?!
WWU engineering student here -- can anyone explain what this means, to me?
@@mccryan3 In other words he's a color commentator for their sporting events, IE announcer.
@@BikingVikingHH Color commentary. Announcing for sporting events.
Those 727s were some sky rippers!!!!!! LOUD AF!!!!!
Now thats what I name a turbo-fan!!!
All I can think of is a flock of birds flying into that thing. Pinata from hell.
@Freemont Tulane Nice try numbnuts!
Haaa , flying saucer ? No ,
Flying slicer ;)
In my apartment (Seattle) a long time ago I heard this strange sound, from my balcony there was a 727 flying by, then I realized it was the unducted fan test aircraft.
I thought is was mounted on the left side, obviously not. ;-)
T'airn'KA
Yeah. The photos I e seen were left mounted. More than one test platform?
Flipped the photo over...
farmer strong
Nope, different aircraft;
ruclips.net/video/1BMNaXc1rL8/видео.html
That is cool. I don't live in Seattle but in Spokane, no we don't get the tests as much but they do come over here sometimes, and back when the 747-8 was being tested I caught it flying over one day on a clear sunny day on a test flight as it was headed to Montana and north Idaho to do zig zags and simulate a longer haul flight before turning around after several circuits over Monatana and Idaho and head to Moses Lake to land. But it had started in Seattle as well. I watched the FlightAware data in anticipation of photo opportunities. Sadly the 747-8 isn't too popular either. The way of the 4 engine jet is also on its way out, and even the A380 is shuttering its program. But sometimes they will land in Spokane too, normally when they are testing a 737 or 787 before its painted or delivered to the customer, also as well as I said Moses Lake. I have seen several 787's in many different airlines liverys pass over my house on tests. Its funny seeing an airline paint scheme from someplace like Asia fly over since it is not a normal visitor here! And another cool thing I see here is the 737 fuselages coming through on trains headed your way from back east. Its cool to see an un-assembled plane with its bare skin pass by on a train, and its usually at least 3-4 airframes rather than just 1 when it does have them.
And yes it is 4 AM. Since you are in my timezone you might call BS on when I am posting this lol, but I am up at 4 AM!
@@RobotWillie I frequently see the big engines on lowboy flatbed trailers headed for Seattle up Interstate 95 through Idaho. Despite being covered with tarps the shape of high bypass turbofan engine outside its nacelle is unmistakable.
Loved the 727
A dear friend of ours, David, RIP worked for GE and helped design these engines..he was a brilliant man..
"The video gives some feel for the engine and important acoustical properties"
Translation, efficient, BUT DAMN IT'S LOUD!
Hey, I remember when all the airliners were fitted with these back in 1992, it revolutionized air travel and now I only pay half a million future-bucks to fly from Wisconsin to Moonbase Alpha, which takes just 13 years.
@@LeonAllanDavis johnmaddenjohnmaddenjohnmaddenjohnmaddenfootball
I love old airplane reports! ✈❤
Super cool sound!
The Brits will love it because it sounds like a Buzz-Bomb!
It sounds like a massive JU-87 about to dive into a target.
Jim johnson sounds excited !!!
I remember seeing ads for these things on Meet the Press when my dad would watch it on Sunday mornings many years ago. I think those ads had them on a DC-9/MD-80 though.
I really like the looks of it.
And it sounds like an angry Stuka m. Imagine a plane with 2 or 4 of them.
I saw it fly over Wilmington ca. Man it was loud. I realized in a few seconds that shock waves of accelerated air coming off the first rotor were causing sonic booms a from the leading edges of the second rotor.. the fix could have been to put razor sharp leading edges on the second rotor bags and increase their pitch significantly as they needed to push the air even faster than the first rotor . Also changing the blade count so all the blades did not line up perfectly every eighth or ninth of a turn. Russians did this eventually.
When ge showed their later primary fan with the convoluted blades my jaw dropped. It was art and efficiency at the same time.
Or to shroud them. So, ducted inducted.....
I think you're on the money with the different pitch different blade count, as well as altering the profile of the individual blades to something both swept back and curving into the direction of rotation, something more organic in appearance.
@@edwardtupper6374 this external fan project died about 35 years ago.. look at the massive inlets on todays crop of jet engines.. the external fan lives on with a duct and on the inlet.
Sounds pretty amazing lol
Best sounding airliner ever
Love the sound and the potential. Eventually even ducted fans will reach their limits and don't panic - somewhere in the future some maverick will resurrect this beasts in newer, better form. They always do...
And It has happened. Check out the CFM RISE
1:53 - this guy must be a hoot at parties.
Can't wait to jet out and see one.
Props to Boeing. Cheers!
Back then they were like "Looks great! Hope I don't die on it, what are we waiting for let's go!"
I'll bet this makes use of the revolutionary turboencabulator
Is this a reference I don't get, or are you trying to sound smart..?
@@cynicalnews963 ruclips.net/video/kkH20fNavoI/видео.html
how did you know.....does it look obvious........if they had adjusted it just right,no one would have heard the blade noise.
Sounds amazing
Well, when you think about it - it's similar to a turbofan, of which most of the thrust is propeller (fan) driven. It's just the fans are on the outside of the cowling. And that sound is wicked.
This was back when the FAA mandated quieter engines phased in over many years in stages. Original 727's were loud as hell.
I love when old media makes bold claims about a products future use. In 6th grade (2010 for me) I read some book saying 'flying cars will be commonplace in 2010' which obviously.. well, you know.
TS remember manganese nodule mining?
There was a great future tech program called "Beyond 2000" on TV in Australia for a few years while I was growing up, I loved it. Little did 10 year old me know that the producers were perhaps being a little bit optimistic in their timeframes when suggesting that we'd all have robot butlers, flying cars, plastics and building materials "grown" by genetically engineered microorganisms, fusion power...
I heard the same thing in 1962 that by 1965 we would have flying cars.
Or that Ford would have engines made of ceramic that did not require liquid cooling by 97? Lol. More flying cars.
@@spacecat7247 if you go off a cliff or fast enough off a ramp, you'll have a flying car
Beautiful.
Quite a while back, an acquaintance made a dual-propeller power unit using two brushed (Speed 480) motors & two concentric driveshafts. He never got as far as putting it in a plane but it did make quite a surprising amount of noise on the bench: the rearmost prop was about 800 rpm behind the forward one at full power.
Man, these April 1 videos are getting out of hand!!!
Look at the publish date...
"Propeller? Don't be ridiculous, this is an unducted fan! Totally different!"
I remember seeing this aircraft at the Farmborough show as a child back in 1988
Props blow!
Who else is having this recommended 2 years later?
2020 and still no UDF powered aircraft. I suspect it was shelved due to noise concerns, a la the Air Force's "Thunderscreech" plane.
the funny thing is that modern turbofans have such a high bypass ratio that they're almost the same thing. Modern airliners on takeoff sound a lot like this.
@@johnyeager3997 Turbo props of this caliber are known to cause nausea, hearing loss, broken blood vessels, and in some cases concussions.
Its more of a concern to ground crews than to residential spaces.
The Russians have some but not used a lot.
@@elykeom1 TU-95
Yeah, it blends
80s were the pinnacle of engineering.
When one of those jet props sheers off, it's coming straight through the plane? With force!
That was my thought from the first time I saw that crazy design. Also they couldn't mount them under a wing for fear of a blade failure piercing the fuel cell in the wing.
That can and has happened even with regular high bypass turbofans
I guess they had some issues getting this engine off the ground.
I’ll kick myself in the ass on the way out.
Yeah,that joke has already been said a year ago
@@johnbravo7542 And it wasn't clever the previous 30 times it was posted either.
Interesting. Never heard of the 7J7 before.
Nothing beats the sound of a JT8
You could certainly see that a tire coming apart might ruin your day, and the engine.
okay this is just hilarious to look at and to hear
Expected the year I was born, at least some videos make me feel young lol
Juice-O-matic. The most powerful juicer conceived by man. “Man, That’s some great juice !”
Had they enclosed the props in a nozzle it may have worked. I never knew this. humm. Or maybe it was too efficient and worked perfectly.
FAA discontinued it because the fans were out in the open and if one broke off might penetrate the fuselage or tail surface. That is why jet engine have an enclosure. To contain a separation.
Tim Bacchus what. Be no different. Than any prop plane. Blade. Strieght. Through the fuselage
Sounds cool
I recall seeing an MD-80 rigged up the same way out of Long Beach, CA in the late 80's as well. Interesting concept.
They did the flight testing work out of Mojave airport at that time.
Damn if we fly this thing in Europe everyone runs in a shelter lol
Better to fly one over Israel back in 1992 and watch them so called Chosen One's hit the deck
Funny. GE - Safran is going this route again with new prototype engines, the CFM RISE program. 20% more efficiency than the CFM LEAP engines.
That was such an awesome idea! But I can only imagine children everywhere screaming in terror from the sound of this thing lol!
Love it.
I wondered what happened to "the missle knows where it is" script reader when he left the air force..
This design would certainly help with "debris" ingestion. I can imagine it would make extremely short work of a flock of geese.
Mais, oui oui, monseiur, c'est le foie gras! Merci! Merci!
the "Geese Blender"!!
The 7j7 is cool
Such a success all planes have them now
2092? Thats gonna be a wait. The damn robots will have taken over by then!
This is not how the 7J7 looked. This is merely a 727 being used as a test bed.
There were a number of issues with the 7J7, including extremely dangerous vibrations that set up in the airframe and not enough room to hide the main gear. One day we were designing it, and the next day it was cancelled. After that, we just never headed that way again.
Watch the video, please!
The 7J7 became the 757
The video said it was just a 727 being used as a test bed for the UDF engine.
@@leifvejby8023 the video clearly says that the 727 was used as a test bed for the engine technology being considered for the future 7J7 program, due around 1992.
This video was made in 1984, by then both the 757 and 767 were in commercial service.
@@twentysevenlitres yes, and?
I see this never passed
That was me, the test pilot. What a beauty it was flying it.
Full send baby
Wow you're lucky!
I wonder if the issue was the safety of airport ramp workers .. as those blades moved at great speed close to the apron.
No, unfortunately, although the SFC was amazing (about half the fuel consumption for similar thrust/cruise velocity), they were extremely loud. Many things were tried to attenuate the resonance (which could be felt in the cabin, as well as on the ground/in the terminal), but nothing was successful.
Ear plugs for everyone.
Maybe. But as an ex-airport ramp worker, my colleagues and I never had any problems working around turbo-prop aircraft.
JetFix: Put the cover- ring around the props, and you'll get more thrust,safety and silence.
Interior noise and the threat of uncontained broken blades made it a non-starter. The large ducted fan of modern jetliner engines made even larger up to 140 inches in diameter was the chosen path instead.
QUOTE: "The GE90 was developed from the NASA 1970s Energy Efficient Engine, a prototype variant of the General Electric CF6.
GE's GE36 Un-Ducted Fan (UDF) was meant to replace the CFM International CFM56 high-bypass turbofan which was initially uncompetitive against the rival IAE V2500. However, when the V2500 ran into technical problems, sales of the CFM56 took off.
GE was not interested in having the GE36 cannibalize the CFM56, and while "the UDF could be made reliable by earlier standards, turbofans were getting much, much better than that." However, GE integrated the UDF's blade technology directly into the GE90."
This looks like a Ultimate booster
Congrats! you made a reverse turboprop