PDA

View Full Version : JetPOD crashes on maiden flight, creater lost...



AirDOGGe
08-19-2009, 07:11 PM
I'm posting this in here because, though not a racer, it shows the dangers of creating entirely new and unique designs of small aircraft without the financial backing and testing capable of a large aircraft manufacturing corporation. I'm hoping SOMETHING here may prove helpful or informative enough in making a difference, and maybe saving someone's life somewhere in the future.

The cause of the crash is unknown, and, judging by the flight path of the airplane, may have been from an elevator problem and not the layout of the airframe. I only say this because the description of the short flight sounds almost identical to those that occur due to a locked or sticking elevator. You decide.

The witnesses statements are noteworthy, especially his description of earlier attempts of flight. What he describes may have only been high-speed taxi tests, or actual unsuccessful flight attempts. Again, we'll find that out later. I will not speculate on that for obvious reasons.

I'll add official findings of the cause later as they become available, May the pilot forever rest in peace, and my condolences to family and loved ones.


http://www.avweb.com/newspics/jetpod-taxi_large.jpg


An experimental STOL jet aircraft with possible military use has crashed during a test flight in Malaysia, killing its British pilot and inventor.

Malaysian civil aviation authorities are investigating the accident of the twin-engine raised-wing Jetpod built by London-based Avcen in which company director Michael Robert Dacre, 53, died.

The accident happened Sunday shortly after takeoff from Tekah airstrip near the city of Taiping, around 190 miles north of the Malaysian capital Kuala Lumpur.

The incident was witnessed by many residents, according to a report in the English-language newspaper The Star.

One witness was only 150 feet from the crash. "Earlier I saw it going down the runway three times but it could not take off. However, on the fourth run, the jet took off into the air but at about 200 meters high, it shot vertically to the sky before veering to its left and then falling to the ground," he said.


The aircraft had been transported in parts in a container to the airstrip about a week ago before being assembled for the test flight, the report said.

The single-pilot Jetpod was designed by Dacre, who set up Avcen in the United Kingdom in 1998 to produce the aircraft.

Few design details are available. The two over-wing turbofan engines were said to have a thrust of 2 X 13.3kn, and the plane had an operating payload of around 1,540 pounds. Its range was to be just more than 900 miles.

The Jetpod was initially marketed as a flying taxi because it needed only 410 feet to take off and land and had a maximum speed of 350 miles per hour.

glenplane
08-22-2009, 11:10 AM
I'm posting this in here because, though not a racer, it shows the dangers of creating entirely new and unique designs of small aircraft without the financial backing and testing capable of a large aircraft manufacturing corporation. I'm hoping SOMETHING here may prove helpful or informative enough in making a difference, and maybe saving someone's life somewhere in the future.

The cause of the crash is unknown, and, judging by the flight path of the airplane, may have been from an elevator problem and not the layout of the airframe. I only say this because the description of the short flight sounds almost identical to those that occur due to a locked or sticking elevator. You decide.

The witnesses statements are noteworthy, especially his description of earlier attempts of flight. What he describes may have only been high-speed taxi tests, or actual unsuccessful flight attempts. Again, we'll find that out later. I will not speculate on that for obvious reasons.

I'll add official findings of the cause later as they become available, May the pilot forever rest in peace, and my condolences to family and loved ones.


http://www.avweb.com/newspics/jetpod-taxi_large.jpg

I can tell by looking at this desighn that the elevator would be
in the wind shadow of the main wing on high angles of attack thus
making it useless. The elevator needs to be much farther back and
lager too. By the way Tsunami was a home built and it won races too.

First time Juke
08-23-2009, 02:08 AM
Sounds like the main landing gear was too aft. :dunno:

AirDOGGe
08-23-2009, 05:24 PM
A too-far-aft landing gear, would make lift-off difficult, but wouldn't make the plane suddenly shoot nose-high from 600 feet alt.

I'm still gonna wait for OFFICIAL reports myself. There's just too many possible things that could cause the tragedy.

First time Juke
08-24-2009, 04:30 AM
I think the Short Skyvan is a good plane in that category.

http://en.wikipedia.org/wiki/Short_SC.7_Skyvan

That must be a difficult task to make that work..first you have to able to load it..keep the CG right..get thrust etc.

The end of the fuse is very non-aeroplane like in form.

What are the holes underneath the wing...nozzles of some sort ?

AirDOGGe
08-24-2009, 04:04 PM
The latest report says, "According to Taiping deputy police chief Supt Syed A. Wahab Syed A. Majid, the company had NOT obtained permission from the Royal Malaysian Air Force to conduct the flight tests... "




...What are the holes underneath the wing...nozzles of some sort ?

Something like that, I assume. I didn't notice those before.

Investigating....

Hmm. The description of the aircraft on one website says "The Jetpod is a Very Quiet Short Take-Off and Landing (VQSTOL) light twin-jet aircraft, can cruise at 300 knots (350 mph, 550 kmh) and requires just 125 metres to take-off or land using a combination of horizontal and vertical thrust.

And another site says "Using thrust management technology, the VQSTOL (Very Quiet Short Take-off and Landing) jetpod also reduces the noise of a regular jet engine by 50 percent..."


Still looking for info on the aircraft concept...(searching...)


OK, here's the description, according to: http://www.prweb.com/releases/2005/01/prweb200545.htm


"1. The Jetpod operating principle of using a through-wing vertical thrust component, along with its unique wing-shape, have been confirmed by City University in London. City have confirmed that the aircraft can take-off or land in a distance of less than 125 metres (410 feet). Also, that the unique wing shape is well suited to low-high speed flight."


So it would appear that some of the jet engine's thrust is routed through the wing vertically to increase lift. At least that's what it was SUPPOSE to do. That would explain the unique top-of-the-wing location of the engines.

Sounds like all this is going to make the investigation more complicated. They have to figure out if this new vertical thrust layout was responsible, there was a control rigging error (the plane was assembled after shipping just days before the flight), there was a flaw in aerodynamics, a defect like a sticking elevator or cockpit control, or (you fill in the blank).

As I said, the possibilities are endless.

First time Juke
08-25-2009, 12:05 AM
Right Airdogge and that plane looked more like an aeroplane afterall...

http://www.dailymail.co.uk/news/worldnews/article-1206919/Michael-Dacre-British-test-pilot-dies-crashing-prototype-plane-flight.html

IcePaq
08-25-2009, 08:25 AM
I think Juke is correct.

The gear being too far aft would cause the elevator input required to shove the rear down enough to lift the nose to get the angle of attack high enough to lift off was probably excessive.

It's possible that the speed at which the elevator could generate enough downforce to pivot the plane on the "too far aft" main gear was high enough such that airplane pitched up rapidly once the wing was able to take weight off the gear and that the difference between the "main gear pivot" and center of lift caused that extreme elevator input to rapidly pitch up the plane once the "pivot point" transferred from main gear to center of lift.

It probably pitched up high enough such that the wings blanked out the airflow over the elevator making it impossible to get enough elevator effectiveness to get the nose back down.

If that is the case, then they overestimated the amount of vertical lift generated forward of the main gear at zero angle of attack by the engine placement and ducting since it's obvious from the pictures that it would never have gotten off the ground with so much weight in front of the main gear in a conventional engine configuration.

AirDOGGe
08-25-2009, 09:48 AM
I think Juke is correct.

The gear being too far aft would cause the elevator input required to shove the rear down enough to lift the nose to get the angle of attack high enough to lift off was probably excessive.





All true, EXCEPT....

The plane wasn't on the runway when it pitched up...It had already left the ground successfully, and witnesses say it was at 600 feet (200 meters) when that happened. But I've already stated that.

Article text:

"...on the fourth run, the jet took off into the air but at about 200 meters high, it shot vertically to the sky "

So, no, I doubt the sudden pitch-up had anything to do with the gear location.

First time Juke
08-26-2009, 12:27 AM
edited

I tried to figure out if the but word is there a typo..

“However, on the fourth run, the jet took off but at about 200m high, it shot vertically to the sky before veering to the left and falling to the ground.”

First time Juke
08-27-2009, 05:38 AM
I think I got the flight pattern right, but the plane seems to have suffered from engine problems....

http://www.flightglobal.com/articles/2009/08/16/331065/jetpod-air-taxi-entrepreneur-killed-in-test-crash.html

AirDOGGe
08-27-2009, 10:30 AM
That's the same witness statement we've already received, except it appears that the writer decided to embellish it with his own "engine problems" comments. None of the other articles quoting the witness said anything about the engines.

"Circumstances of the accident have yet to be established..."

That's about the only accurate thing he wrote...


"...but a witness at the crash site tells Flightglobal that the aircraft had already made three runs, during each of which there appeared to be engine problems."

Speculation. No other report of the witness mentioned engine problems.



"It made a fourth attempt to become airborne, he says, and took off at about 12:45, entering a "sharp climb". It appeared to suffer a problem with its left-hand engine, he says, at about 500-700ft, then yawed sharply to the left and crashed."

This makes it sound like the plane went into a steep climb as soon as the wheels left the ground and climbed to 200 meters before rolling over, but ALL other reports say the plane took off normally and reached 200 meters BEFORE THE PITCH-UP.



How would the unknowing and un-involved witness know if the first 3 runs were not just high-speed taxi tests, as done with many first-time-flight aircraft? How does he know the extremely steep climb/stall/left side pitch-over wasn't just a plain-ol' stall, as would be expected with such a maneuver, and how could a failing left side engine cause the plane to pitch-up so steeply like that in the first place?

I'm taking this report as a "colorized" version of the previous ones, spruced-up by the author so that his report doesn't sound like an exact copy of what's already out there, of which it does except for the addition of a mention of engine problems and the shuffling of a few details. He mentions no new sources of info, and especially not any OFFICIAL sources.

:eek13:
.

IcePaq
08-27-2009, 09:27 PM
Hmmm.......I wonder if the pilot really had no intention to do more than some high speed taxis with a bit of control movement to get a feel for the control authority without fully leaving the ground?

Maybe just enough elevator to get the nosewheel up was all he intended.

One would think that the pilot would have had someone filming the first flight of his crowing achievement and the lack of video might mean he wasn't planning on it flying that day.

Just a guess.

AirDOGGe
08-27-2009, 09:39 PM
One would think that the pilot would have had someone filming the first flight of his crowing achievement...




Maybe he did, but if so said footage would now be in the hands of Malaysian officials and both Malaysian AND British investigators....

Perhaps he DIDN'T originally plan on taking off as you say, but did anyway inadvertently,( or intentionally like Hughe's did in his Spruce Goose). His lack of any permissions to test-fly it there would seem to say so, and many older, pre-crash articles I've found seem to say they were hard-pressed to get it flying so they could attract some badly-needed investors.



I did an unsuccessful search of any crash footage on the web, so possibly no cell-phone cameras were in witness. Stuff like that usually pops up quickly on the web.

I DID find an early intro film of the aircraft, but not much is learned from it. The narrator just mentions "new technologies" and says little else we don't already know of. I wish I could find some details of this "thrust management system".

LINK:
http://www.youtube.com/watch?v=ysCbOs6LnBQ



And here's another worthless 30 sec "teaser". They sure kept mum about it.

LINK:
http://www.youtube.com/watch?v=zJ1rVvwYtBY&feature=related

First time Juke
08-30-2009, 04:05 AM
Hmmm.......I wonder if the pilot really had no intention to do more than some high speed taxis with a bit of control movement to get a feel for the control authority without fully leaving the ground?

Maybe just enough elevator to get the nosewheel up was all he intended.

One would think that the pilot would have had someone filming the first flight of his crowing achievement and the lack of video might mean he wasn't planning on it flying that day.

Just a guess.

Ice Pack..the pilot did not take the co-pilot mechanic on the test run..possibly in order to attempt a take off and did not want to risk anyone elses life.

AirDOGGe
08-30-2009, 06:23 PM
WHat "co-pilot/mechanic" ? I haven't seen one mentioned anywhere.

Where did you read about him?

:dunno:

First time Juke
08-31-2009, 01:08 AM
Naturally in the internet concerning the case.

First time Juke
08-31-2009, 09:25 AM
Last paragraphs here; http://thestar.com.my/news/story.asp?file=/2009/8/17/nation/4533356&sec=nation

AirDOGGe
08-31-2009, 05:14 PM
I've read that one before, but I didn't want to post that article because of the gruesome way the author describes the recovery of the pilot's body. That part of the text wasn't necessary, and was unkind to the family of the deceased...


The text mentions a co-pilot suggesting he go along, but nothing about him also being a mechanic. That's the part I haven't seen mentioned anywhere and was asking about.


The only new "news" I have seen is a local article (local to the accident site) stating that they are keeping the pilot's body at Taiping Hospital, and not letting the family bring him home to the U.K. until further investigations of the accident are completed.

Link: http://www.bernama.com/bernama/state_news/news.php?id=433915&cat=nt


.

AAFO_WSagar
08-31-2009, 07:55 PM
The description of the crash in the link Juke posted earlier is a gross example of TMI when it comes to reporting.. far too graphic!!

First time Juke
09-02-2009, 06:47 AM
I've read that one before, but I didn't want to post that article because of the gruesome way the author describes the recovery of the pilot's body. That part of the text wasn't necessary, and was unkind to the family of the deceased...

The text mentions a co-pilot suggesting he go along, but nothing about him also being a mechanic. That's the part I haven't seen mentioned anywhere and was asking about.


Right the co-pilot could have been a mechanic..that was my assumption.

This was not very polite towards the inventor and his family I agree to explain all details.

AirDOGGe
09-02-2009, 08:45 AM
Right the co-pilot could have been a mechanic..that was my assumption....

Ah. Well, let's not ADD any details to the accident info to keep facts accurate and rumors/mis-conceptions to a minimum, please.

:thumbsup:

First time Juke
09-03-2009, 12:36 AM
Ah. Well, let's not ADD any details to the accident info to keep facts accurate and rumors/mis-conceptions to a minimum, please.

:thumbsup:

What diffrence does it make here..the point was that the pilot refused to take co-pilot with him since he was about to take off...and not taxi the plane. Wasn't this what Ice Pack assumed ?

IcePaq
09-14-2009, 07:09 AM
My assumption is that he didn't take the other guy along because he only intended to fast taxi the plane and maybe move the elevator a bit to see what kind of authority it had but the design dictated that the huge amount of force necessary to affect any pitch change was more than enough to cause problems if the wing generated any amount of lift.

There have been similar accidents involving planes with main gear too far aft of the center of lift that ended the same way.

AirDOGGe
09-20-2009, 02:59 PM
What diff does it make HERE? I believe that accuracy of info is VERY important at AAFO, and ESPECIALLY at AAFO.

ANYWAY...

All this talk of gear location and elevator issues being the cause ignores the fact that this is an STVOL, and is suppose to use some ducted jet thrust to lift-off. How do you know it's not a propulsion-related issue?


Too many potential culprits (shakes head).


Meanwhile, here's some ACCURATE info related to the issue:


TAIPING: No flight plan was filed for the maiden test flight of the Jetpod which crashed at the Tekah airstrip here on Sunday, killing its inventor Michael Robert Dacre.



The Civil Aviation Department said the test flight was not registered in the Civil Aircraft Register.



MCA vice chairman Datuk Ho Cheng Wang said the Tekah airstrip was no longer surrounded by jungles as in the old days.

“The airstrip is now surrounded by housing estates and who is going to be responsible had the plane crashed into some houses in the vicinity?” he asked.

The airstrip is not suitable for conducting test flights.



Taiping deputy OCPD Superintent Syed A. Wahab Syed A. Majid said since the airstrip was surrounded by housing schemes, advice from the police should have been sought.

“Although we are not empowered to approve or disapprove the maiden test flight, we would have studied the matter and given our views because we must also think about the safety of civilians in the vicinity,” he said.

IcePaq
09-20-2009, 11:06 PM
I've been following the jetpod saga since it started and even sent an e.mail to about 5 years ago telling them what would they were up against if they used that configuration on the finished plane.

I actually found this forum while performing a search for a thread in another forum where I predicted it would pitch up and crash if it somehow generated enough elevator downforce to even lift the nose at all.

I'll try to dig up flight test data from other planes that had "too far aft" main gear that experienced dangerous pitch up because of the configuration.

I made an educated guess but it doesn't take a genius to see that the jetpod will experience violent pitch up once it goes fast enough to gain enough elevator authority to even lift the nose with that short arm and the fulcrum transfers from the main gear to the center of lift.

I'm actually surprised that he even got the nose up at all and I'll venture a bet that it happened at a very high rate of speed when it did.

On top of the main gear being too far aft, the engines are too high and will pitch the plane nose down under thrust requiring even more downforce from the tail so.....it's even possible that the plane pitched up AFTER he pulled power if he had any elevator in it while powering down the runway.

It's also obvious that the Jetpod would experience a nasty nose gear touchdown after the mains are down because of the main gear location.........unless the plan was to land with very high power setting and ducting mucho thrust downward near the front of the wing.....which would still make landings on a short field near impossible since I doubt jetpod can divert anywhere near the percentage of thrust downward required to counteract the short arm from tail to wing on an approach and still not have too much thrust propelling the plane forward such that it can decelerate.

The band-aid to tame such a configuration would be a high angle of attack while sitting on the gear much like what they did with the F7U cutlass or maybe a higher angle of incidence in the wing such as in the F8 which would eat into speed and efficiency unless it was also able to be adjusted in flight as the F8's wing is.

As the matter of fact, the F7u had main gear that moved further forward for take off than for landing.

I stand by my guess and challenge anybody to find a picture of a flyable plane with the main gear as far aft as the jetpod relative to the tail and the center of lift from the main wing.

The only flyable planes you will find with gear that far aft of main wing's center of lift will have canards up front or have an excessively high nose high attitude while sitting on the mains.

http://www.voughtaircraft.com/heritage/photo/assets/images/db_images/db_1240_081.jpg

AirDOGGe
09-21-2009, 01:07 AM
I'd have to know far more of the actual internal design and concept to venture a true argument, but there's a few points I can make:


--> The assumption is made that the plane was intended to pitch-up like a conventional design to achieve take-off. How you you know the aircraft wasn't suppose to achieve flight with a more level stance, ala B-52 and AN-124? Those aircraft both sit level at static and during take-off, yet manage to get off the ground just fine at said level attitude even with far-aft main gear locations.

The mentioned Boeing bomber has it's rear-located gear set WAY aft of it's center-of-lift and C/G, and I'd LOVE to see someone try to pitch up the Antonov with it's lengthy caterpillar-type gear arrangement. Neither machine requires a pitch-up maneuver to obtain flight, and as far as I know, neither has canards up front. ;)


--> How does anyone not involved know if the unconventional jet thrust ports, located AHEAD of the main gear, were intended to provide the "push" the close-coupled elevator needed to lift the nose, or provide enough upward push to get it off the ground without said pitch-up?

--> Artist drawings available show very large flaps situated below the wing and above the main gear, with most of said flap appearing to be in front of those wheels. Perhaps those (along with the vertical thrust component) were to provide the lift to get it off the ground without the pitch-up maneuver you suggest.

Again, not enough detail has been revealed about this unique system to venture a true EDUCATED guess, and so using conventional aircraft designs as examples may not apply. Details of this thrust/flap system haven't been forthcoming, and possibly never will now.



--> And finally, the assumption is made again that the severe pitch-up and resulting loss of control happened while the gear was still on the ground, yet initial reports state that the plane had ALREADY left the ground, and had successfully reached 200 meters of altitude BEFORE the pitch-up occurred. The gear location would be a non-factor if this is the case.


I agree that a CONVENTIONAL aircraft with such a short-coupled T-tail would experience pitch problems at take-off, but then this is far from a conventional concept.

This is why I say, much more info of this one-of-a-kind design would have to be forthcoming BEFORE any form of real educated guess could be made by myself. What applies to apples may not apply to oranges.

:cool:

First time Juke
09-21-2009, 03:24 AM
I've been following the jetpod saga since it started and even sent an e.mail to about 5 years ago telling them what would they were up against if they used that configuration on the finished plane.

I stand by my guess and challenge anybody to find a picture of a flyable plane with the main gear as far aft as the jetpod relative to the tail and the center of lift from the main wing.


I bet that is the reason why Molt Taylor Aerocar looks how it does..the added tail actually shifts the CG dramatically from automode to aeromode.

I have not seen a single pic how the Jetpod looked like before the mishap.

IcePaq
09-21-2009, 08:55 AM
The B52 gets around the aft main gear location with a main wing that is mounted extremely far forward to lift the front in addition to having huge flaps mounted right behind the engines.

Had the jetpod had the engines mounted under the wings acting on flaps the way the B52 does, there would have been no need for ducting thrust downward.

Sure it takes off flat but the B52 has more than enough length between the wing and the tail in addition to having lift far enough forward to lift the front without considerable downward pressure from the tail.

http://www.alaska.faa.gov/fai/images/Aircraft/B52-a.jpg

The An124 has a very long arm with which the tail can act in lifting the nose and the gear is not nearly as far aft in relation to the plane's center of gravity as in jetpod and it certainly does not take off flat.

It also has the engines acting on large flaps under the wings.

Neither of those planes has the engines mounted high forcing the nose down.

http://www.youtube.com/watch?v=KkQyet-mREg

I'll come back to this thread once the investigation is over and see whether my guesses were correct but further discussion seems to be headed toward an argument so I will only view this thread until the experts post thier findings on the incident.

AirDOGGe
09-21-2009, 10:18 AM
Not correct about the engines blowing on the flaps to increase lift. That wasn't done until the C-17, and is why it's engines are mounted close-to and forward of the wing on shorter-than-usual pylons, rather than well below like the older aircraft.

On the Boeing, large gaps exist BETWEEN the flaps to allow the jet thrust to blow directly back. Said older aircraft's flaps weren't designed for hot exhaust to strike them.

http://www.aerospaceweb.org/aircraft/bomber/b52/b52_04.jpg

If you watched many B-52'a take off, sometimes the rear wheels actually lift off before the fronts.

And the AN's engines are mounted well below the wings on tall pylons, so that their exhaust does not strike the full-span flaps.


And despite the forward location, the Boeing's wings are swept far aft, so the center of lift is much farther back than you state.


Having the engines mounted on top does not impede flight as much as you say. Having personally worked on NASA's QSRA research aircraft at AMES (the wind tunnel model actually), and having seen the actually aircraft make many successful take-offs, I can say that having the turbines on top of the wing works just fine. In fact, that aircraft gets off the ground in shorter distances than most.

http://www.aviationsystemsdivision.arc.nasa.gov/multimedia/simac/images/qsra_lo.jpg


Anyway, If you look at pics of the Jetpod, you can see that most of IT'S it's wing is also set well forward on the airframe, so the Boeing wing-location argument applies to it as well. Along with the large flaps and vertical thrust component, it should have no problem getting off the runway without a conventional pitch-up.


Along with JUKE, I too have not seen any real photos of the J-pod, only drawings. as such, NONE of us have any idea of the actual aircraft that was flown and lost, only drawings that show some detail but leave out so much more. Things could have changed since these were released:

http://planetagadget.com/wp-content/uploads/2008/05/jetpod-3.jpg


Scholars familiar with this aircraft's design have already investigated and confirmed the wing layout as being capable of short distance take-offs, and since they have seen the details we haven't, I tend to trust their opinions:



The Jetpod operating principle of using a through-wing vertical thrust component, along with its unique wing-shape, have been confirmed by City University in London. City have confirmed that the aircraft can take-off or land in a distance of less than 125 metres (410 feet).


The rear-mounted gear location is obvious, so if the design wasn't intended to compensate for it, surely that point would have long-since been addressed and dealt with.


Finally, you are still ignoring the point that the plane may have already been in flight at the height of a 60-story building BEFORE control was lost, where gear locations and pitch-ups from the runway do not apply:

Witness statement:

"...on the fourth run, the jet took off into the air but at about 200 meters high, it shot vertically to the sky before veering to its left and then falling to the ground,"

If it had said that the pitch up to vertical flight had occurred while trying to leave the runway, then I might be agreeing with your viewpoints, but that doesn't seem to be the case here.



In any case, This has been a good discussion and I don't see it leading to any kind of unacceptable arguments. I have enjoyed the debate myself, as you offered some pretty good counter-points.


But I DO agree that waiting until further official investigation is completed is the next best step for this topic. Neither you nor I have enough real info to take it further. Of course, I've been saying that since I started this thread ;). As I like to say, IT'S ALL GOOD.


Take care, be well, and thank you for taking up the topic with me.

:beerchug:

First time Juke
09-22-2009, 03:48 AM
Not correct about the engines blowing on the flaps to increase lift. That wasn't done until the C-17, and is why it's engines are mounted close-to and forward of the wing on shorter-than-usual pylons, rather than well below like the older aircraft.

On the Boeing, large gaps exist BETWEEN the flaps to allow the jet thrust to blow directly back. Said older aircraft's flaps weren't designed for hot exhaust to strike them.

http://www.aerospaceweb.org/aircraft/bomber/b52/b52_04.jpg

If you watched many B-52'a take off, sometimes the rear wheels actually lift off before the fronts.



Take care, be well, and thank you for taking up the topic with me.

:beerchug:

Yeah 2 aspects make b-52 special..gear layout saves weight and ailerons don't produce negative lift when deployed.

Like seen here...the flaps are enermous.

Jetpod fuse seemed to me quite short...doesn't that make AC easily unstable at take off and flight ?

AirDOGGe
09-22-2009, 08:42 AM
yes, but the Questair Venture guys seem to have little trouble with short-coupled layouts...

http://www.advancedcompositesolution.com/gallery/thumbnails/P1010736.JPG


...And Northrop's flying wings are about as short coupled as you can get, with the elevators right on the trailing edge of the wing!

http://www.ctie.monash.edu.au/hargrave/images/northrop_xb-35.jpg

Short aircraft will be more touchy than those with a long fuselage, but they manage to get by that limitation.

First time Juke
09-23-2009, 08:38 AM
...And Northrop's flying wings are about as short coupled as you can get, with the elevators right on the trailing edge of the wing!

Short aircraft will be more touchy than those with a long fuselage, but they manage to get by that limitation.

How come I have a haunch that test pilot Robert Gardenas might have a different opinion ?

AirDOGGe
02-05-2011, 08:28 PM
Apologies for bringing this topic back to life but footage of the incident was recently discovered on Youtube.


IMPORTANT: The pilot/designer was lost in this tragedy, so please don't watch if viewing such may upset you.


http://www.youtube.com/watch?v=VapC_CxzQlw&feature=related

First time Juke
02-06-2011, 12:06 PM
Somehow reminds of this crash of a prototype.

http://www.pacificnorthwestflying.com/index.php?PHPSESSID=8f8fa716ddc889046fec77a3673f92 f6&topic=4081.0

Chad Veich
02-07-2011, 10:30 PM
One thing we can now be sure of, he did not achieve 600' altitude before the pitch up.

kiwiracefan
02-08-2011, 12:42 AM
One thing we can now be sure of, he did not achieve 600' altitude before the pitch up.

no... looks like it pitched up as it lifted off... straight into a verticle where it ran out of airspeed

RichH
02-08-2011, 10:22 AM
As IcePaq was saying...

AirDOGGe
02-08-2011, 08:38 PM
Yep. Makes me think the T-tail may have been at least partially involved now.


Many T-tailed aircraft require a good pull on the wheel to get the nose up for lift-off, since the elevator is up high and out of the boosting effect of the prop airflow. Once up you have to quickly push forward again to maintain the correct pitch else you end up rotating the nose up too high.

If you DON'T perform this little extra-pull maneuver then you may just end up simply scooting down the runway on a Sunday cruise.


Since the designer/pilot had already made 3 attempts to get off the ground and couldn't, then did the major pitch-up maneuver on the last and final run, I suspect this I speak of may have been at least partially responsible. I also would wager that he didn't have any significant T-tail time.

First time Juke
02-13-2011, 10:23 AM
I have a feeling deploying the flaps fully was not a good idea. CG may have been too aft and gear placed dangerously aft. Also the elevator looks very very small...and stabilizer too big..IMHO.

IcePaq
03-19-2011, 08:54 PM
Terminal pitch up right at rotation.

I figured that the initial reports of it pitching up after it attained 200 meters were incorrect.

I think the video supports my earlier posts.