Skymaster Viper ..... unexplained crash??
07-10-2010, 10:02 AM
#27
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RE: Skymaster Viper ..... unexplained crash??
ORIGINAL: ianober
Something induced the spin, looks like lockout or flight control failure.
Something induced the spin, looks like lockout or flight control failure.
Smoke all the way to the ground. No turbine shutdown. Snapped out at the bottom of a roll.
I did the same thing on a Bandit ARF. Had a high wing loading and too much expo in the elevator. Pulled a little to aggressive in a banked turn.
Now I use no more than 20% expo.
07-10-2010, 10:33 AM
#28
RE: Skymaster Viper ..... unexplained crash??
If it was really a radio issue, then why did the turbine never shut down? Granted, its over-seas so they may not be required to set it up that way, but i dont understand why any responsible turbine pilot would attempt to fly a plane with limited control with the turbine running. And why even attempt a loop if you knew you were having radio issues and with the landing gear down at the airspeed and altitude he was at?
IMO, their is far to much missing from this story to say that it was entirely pilot error. Looking at the video.. the gear went down (minus the nose) then went back up, and then was back down for the loop/stall/spin crash... maybe the failsafe had kicked in during that time? Personally, dont know.. but i'd like to hear the pilots side of the story
IMO, their is far to much missing from this story to say that it was entirely pilot error. Looking at the video.. the gear went down (minus the nose) then went back up, and then was back down for the loop/stall/spin crash... maybe the failsafe had kicked in during that time? Personally, dont know.. but i'd like to hear the pilots side of the story
07-10-2010, 10:50 AM
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RE: Skymaster Viper ..... unexplained crash??
I watched the video magnified and it looks very much like the left flap stayed down and the right flap was flat and loose.. this would cause the roll to the right and elevator would only cause the downward plunge when inverted.... really sorry you lost your plane bud,,,,, i have been there I few times myself,, pilot error is too easy to say..... whatever,.... it's always a big hurt when you loose a plane,,,,best wishes for the future...MK
07-10-2010, 11:25 AM
#31
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RE: Skymaster Viper ..... unexplained crash??
accelerated stall as was stated before.
Speed into spin may have over ridden 1 flap servo causing asymetrical flap deployment. Note flap on non-stalled wing (with more air pressure) retracted.
To aggressive on maiden flight. Need to lean the plane.
Doubt radio issue. Just stall into spin.
Speed into spin may have over ridden 1 flap servo causing asymetrical flap deployment. Note flap on non-stalled wing (with more air pressure) retracted.
To aggressive on maiden flight. Need to lean the plane.
Doubt radio issue. Just stall into spin.
07-10-2010, 12:16 PM
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RE: Skymaster Viper ..... unexplained crash??
it also looks like he had 15 degree of flap through out the flight. hmmm not sure why he would want flaps deployed when he is in aerobatic mode same with gear down. Flaps in a high speed loop that's a no no, so he could have lost a servo during the loop which would also cause the death spiral. So here you have it, Pilot Error (IMO)... sorry to say that but I wish you best in your next jet.
07-10-2010, 12:58 PM
#34
RE: Skymaster Viper ..... unexplained crash??
I'd venture to say a high speed stall that exited into an aileron/elevator spiral, not a spin. I'm just assuming, but the downward velocity seems to high for a spin, plus the rotation is too slow for a spin as well IMHO. Now, if a flap "blew back" as it's called in big boy flying...you were doomed because of the low altitude that the failure occurred.
Either way, it's probably pilot error.
Sorry Mate, it was a beautiful jet.
Beave
Either way, it's probably pilot error.
Sorry Mate, it was a beautiful jet.
Beave
07-10-2010, 01:03 PM
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RE: Skymaster Viper ..... unexplained crash??
ORIGINAL: RCFlyerDan
Yes, it is called an accelerated stall!
Accellerated Stall - The accelerated stall usually surprises a pilot because it occurs at a higher airspeed than a normal stall (in which a wing loading of 1 G is maintained). Remember, a wing can be made to stall at any speed—all that has to happen is for the angle of attack to get high enough. As G-loading increases, so does stall speed. If a wing reaches its critical angle of attack when the wing loading is 2 G, twice normal, the stall will occur at a speed that’s proportional to the square root of the wing loading. The square root of 2 is approximately 1.41, so the stalling speed at 2 G will be 1.41 times what it would be under 1 G conditions. Accelerated stalls are often caused by abrupt or excessive control inputs made during steep turns or pull-ups. If you’re in a dive and pull back with enough suddenness and force to load the airplane to a typical design load factor of 3.8 G’s, you’ll enter an accelerated stall if the airspeed drops below 1.95 times the stall speed at 1 G loading (the square root of 3.8 is approximately 1.95).
Yes, it is called an accelerated stall!
Accellerated Stall - The accelerated stall usually surprises a pilot because it occurs at a higher airspeed than a normal stall (in which a wing loading of 1 G is maintained). Remember, a wing can be made to stall at any speed—all that has to happen is for the angle of attack to get high enough. As G-loading increases, so does stall speed. If a wing reaches its critical angle of attack when the wing loading is 2 G, twice normal, the stall will occur at a speed that’s proportional to the square root of the wing loading. The square root of 2 is approximately 1.41, so the stalling speed at 2 G will be 1.41 times what it would be under 1 G conditions. Accelerated stalls are often caused by abrupt or excessive control inputs made during steep turns or pull-ups. If you’re in a dive and pull back with enough suddenness and force to load the airplane to a typical design load factor of 3.8 G’s, you’ll enter an accelerated stall if the airspeed drops below 1.95 times the stall speed at 1 G loading (the square root of 3.8 is approximately 1.95).
07-10-2010, 01:13 PM
#36
RE: Skymaster Viper ..... unexplained crash??
There are so many things wrong with that flight, the gear cycles at least once, its down when he enters the loop and the one flap down also, this would induce the spiral dive that happened (sorry it was not a spin) an accelerated stall spin would have rotated much faster as well, IMO the assermetric drag from the one flap down, too slow, too heavy and agressive use of the elvator all contributed to what happened.
Mike
Mike
07-10-2010, 01:23 PM
#37
RE: Skymaster Viper ..... unexplained crash??
With all deference to Ali, who is certainly knowledgable and talented beyond a level that most of us could even dream of:
This was, IMO, NOT a stalled airplane. Look at all of that barrel/spiral. BOTH wings were still "flying" or the flight path would have not spiraled.
At the very least, the case for pilot error is not "clear", as stated by Ali and those who jumped onto his band wagon.
That was my take on it even before I saw the magnified freeze-frame of the assymetrically deployed flap, which seals the deal.
This was almost certainly NOT caused by a "tip" stall, accel stall, snap, spin, too much elevator, too slow, too low, gear down etc....The ONLY, repeat ONLY thing that is "clear" here is that for some unknown reason, a reason that cannot be inferred from the video, there was an assymetrical flap condition. It could have been a linkage failure. Or not. It could have been a servo failure. Or not. It could have been a radio component (rx, matchbox, extension, etc) failure. Or not.
Praises to MACH 1 who actually searched for facts rather than dressing his opinions up in pretty little fact suits and inserting them into the thread as "case closed".
And my apologies (on behalf of my too-quick-too-judge RC brethren) to the pilot who's "dumb thumbs" were accused, tried, convicted, and then sentenced on such faulty grounds........
(nicely said)
Again, I don't think either wing was stalled. That said, even IF that were the case then the stalled wing would be the right wing, the wing with the flap retracted. The plane was rolling right.
Who says it's a no-no? Who says it was a "high speed loop"? (everyone else seems to be condemning the guy for being too slow) Who says the servo wasn't a stout, high quality, metal geared unit ? I think it's at least as factual to say that lots of flaps get deployed at higher speeds every day without failure. But that's just my opinion based on guesses
C'mon, y'all. It's human nature, I suppose, to see a vid like this and WANT TO BELIEVE that it wouldn't happen to us (or our wallets and pride) because we are somehow smarter than the guy who was on the sticks. But WANTING it to be true does not make it so...........
Enuff bashing of the poor guy already.
This was, IMO, NOT a stalled airplane. Look at all of that barrel/spiral. BOTH wings were still "flying" or the flight path would have not spiraled.
At the very least, the case for pilot error is not "clear", as stated by Ali and those who jumped onto his band wagon.
That was my take on it even before I saw the magnified freeze-frame of the assymetrically deployed flap, which seals the deal.
This was almost certainly NOT caused by a "tip" stall, accel stall, snap, spin, too much elevator, too slow, too low, gear down etc....The ONLY, repeat ONLY thing that is "clear" here is that for some unknown reason, a reason that cannot be inferred from the video, there was an assymetrical flap condition. It could have been a linkage failure. Or not. It could have been a servo failure. Or not. It could have been a radio component (rx, matchbox, extension, etc) failure. Or not.
Praises to MACH 1 who actually searched for facts rather than dressing his opinions up in pretty little fact suits and inserting them into the thread as "case closed".
And my apologies (on behalf of my too-quick-too-judge RC brethren) to the pilot who's "dumb thumbs" were accused, tried, convicted, and then sentenced on such faulty grounds........
I watched the video magnified and it looks very much like the left flap stayed down and the right flap was flat and loose.. this would cause the roll to the right and elevator would only cause the downward plunge when inverted.... really sorry you lost your plane bud,,,,, i have been there I few times myself,, pilot error is too easy to say..... whatever,.... it's always a big hurt when you loose a plane,,,,best wishes for the future...MK
Note flap on non-stalled wing (with more air pressure) retracted.
Flaps in a high speed loop that's a no no, so he could have lost a servo during the loop which would also cause the death spiral...(pilot error)
C'mon, y'all. It's human nature, I suppose, to see a vid like this and WANT TO BELIEVE that it wouldn't happen to us (or our wallets and pride) because we are somehow smarter than the guy who was on the sticks. But WANTING it to be true does not make it so...........
Enuff bashing of the poor guy already.
07-10-2010, 01:27 PM
#38
RE: Skymaster Viper ..... unexplained crash??
ORIGINAL: SinCityJets
That's a great explanation of it!
ORIGINAL: RCFlyerDan
Yes, it is called an accelerated stall!
Accellerated Stall - The accelerated stall usually surprises a pilot because it occurs at a higher airspeed than a normal stall (in which a wing loading of 1 G is maintained). Remember, a wing can be made to stall at any speed—all that has to happen is for the angle of attack to get high enough. As G-loading increases, so does stall speed. If a wing reaches its critical angle of attack when the wing loading is 2 G, twice normal, the stall will occur at a speed that’s proportional to the square root of the wing loading. The square root of 2 is approximately 1.41, so the stalling speed at 2 G will be 1.41 times what it would be under 1 G conditions. Accelerated stalls are often caused by abrupt or excessive control inputs made during steep turns or pull-ups. If you’re in a dive and pull back with enough suddenness and force to load the airplane to a typical design load factor of 3.8 G’s, you’ll enter an accelerated stall if the airspeed drops below 1.95 times the stall speed at 1 G loading (the square root of 3.8 is approximately 1.95).
Yes, it is called an accelerated stall!
Accellerated Stall - The accelerated stall usually surprises a pilot because it occurs at a higher airspeed than a normal stall (in which a wing loading of 1 G is maintained). Remember, a wing can be made to stall at any speed—all that has to happen is for the angle of attack to get high enough. As G-loading increases, so does stall speed. If a wing reaches its critical angle of attack when the wing loading is 2 G, twice normal, the stall will occur at a speed that’s proportional to the square root of the wing loading. The square root of 2 is approximately 1.41, so the stalling speed at 2 G will be 1.41 times what it would be under 1 G conditions. Accelerated stalls are often caused by abrupt or excessive control inputs made during steep turns or pull-ups. If you’re in a dive and pull back with enough suddenness and force to load the airplane to a typical design load factor of 3.8 G’s, you’ll enter an accelerated stall if the airspeed drops below 1.95 times the stall speed at 1 G loading (the square root of 3.8 is approximately 1.95).
07-10-2010, 01:59 PM
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RE: Skymaster Viper ..... unexplained crash??
Sorry HH, there is no asymetrical flap condition. Look at the video again and not just one blurry, fuzzy frame. You can clearly see both flaps down, both during the loop and the accelerated stall to the ground.
I am certainly not calling anyone dumb thumbs, but pilot error IS what put that plane in to the ground (I don't know anything about the wing-loading and other factors of the plane that MAY have contributed to the accelerated stall). I am not jumping on anyone's band-wagon, but I have seen this occur myself on a nose-heavy, high wing-loaded bandit. Exact same flight characteristics.....right to the ground. Only solution, release elevator, get it flying again and pull up.....IF you have the altitude. Otherwise, shut off turbine and deploy crash recovery vehicle.
Chad
I am certainly not calling anyone dumb thumbs, but pilot error IS what put that plane in to the ground (I don't know anything about the wing-loading and other factors of the plane that MAY have contributed to the accelerated stall). I am not jumping on anyone's band-wagon, but I have seen this occur myself on a nose-heavy, high wing-loaded bandit. Exact same flight characteristics.....right to the ground. Only solution, release elevator, get it flying again and pull up.....IF you have the altitude. Otherwise, shut off turbine and deploy crash recovery vehicle.
Chad
07-10-2010, 02:28 PM
#41
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RE: Skymaster Viper ..... unexplained crash??
ORIGINAL: highhorse
Who says it's a no-no? Who says it was a ''high speed loop''? (everyone else seems to be condemning the guy for being too slow) Who says the servo wasn't a stout, high quality, metal geared unit ? I think it's at least as factual to say that lots of flaps get deployed at higher speeds every day without failure. But that's just my opinion based on guesses
C'mon, y'all. It's human nature, I suppose, to see a vid like this and WANT TO BELIEVE that it wouldn't happen to us (or our wallets and pride) because we are somehow smarter than the guy who was on the sticks. But WANTING it to be true does not make it so...........
Enuff bashing of the poor guy already.
Flaps in a high speed loop that's a no no, so he could have lost a servo during the loop which would also cause the death spiral...(pilot error)
C'mon, y'all. It's human nature, I suppose, to see a vid like this and WANT TO BELIEVE that it wouldn't happen to us (or our wallets and pride) because we are somehow smarter than the guy who was on the sticks. But WANTING it to be true does not make it so...........
Enuff bashing of the poor guy already.
07-10-2010, 02:50 PM
#42
RE: Skymaster Viper ..... unexplained crash??
ORIGINAL: SinCityJets
Sorry HH, there is no asymetrical flap condition. Look at the video again and not just one blurry, fuzzy frame. You can clearly see both flaps down, both during the loop and the accelerated stall to the ground.
I am certainly not calling anyone dumb thumbs, but pilot error IS what put that plane in to the ground (I don't know anything about the wing-loading and other factors of the plane that MAY have contributed to the accelerated stall). I am not jumping on anyone's band-wagon, but I have seen this occur myself on a nose-heavy, high wing-loaded bandit. Exact same flight characteristics.....right to the ground. Only solution, release elevator, get it flying again and pull up.....IF you have the altitude. Otherwise, shut off turbine and deploy crash recovery vehicle.
Chad
Sorry HH, there is no asymetrical flap condition. Look at the video again and not just one blurry, fuzzy frame. You can clearly see both flaps down, both during the loop and the accelerated stall to the ground.
I am certainly not calling anyone dumb thumbs, but pilot error IS what put that plane in to the ground (I don't know anything about the wing-loading and other factors of the plane that MAY have contributed to the accelerated stall). I am not jumping on anyone's band-wagon, but I have seen this occur myself on a nose-heavy, high wing-loaded bandit. Exact same flight characteristics.....right to the ground. Only solution, release elevator, get it flying again and pull up.....IF you have the altitude. Otherwise, shut off turbine and deploy crash recovery vehicle.
Chad
Actually, I did look at the entire vid several times, some portions MANY times.
The flap assymetry is intermittent. Something screwy was going on with the flaps. And if that isn't a hard fact, then there is certainly enough evidence to chalk it up as one very STRONG theory. Even when taking into account the sun angle, aspect, etc the inside wing looks clean, then dirty again. I don't think that the "fuzzy" frame is inconclusive at all !! Certainly not 'fuzzy" enough to be completely ignored so that a "pilot error" verdict can be more readily shoved down the poor guy's throat as if THAT is a solid fact.
07-10-2010, 03:06 PM
#43
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RE: Skymaster Viper ..... unexplained crash??
I was looking for a different video, the one I was looking for was a Hawk or L-39 flying over a frozen lake that does a slow fly-by them tip stalls on the pull out.
Here is another one though that does an accelerated stall on a bank (same thing my plane did)
[youtube]http://www.youtube.com/watch?v=pj9bExCIyT0[/youtube]
I am sorry that my (and most everyone else's) opinion (as they are all opinions) do not match up with yours. I don't know why you would say the flaps are moving up and down rather than saying the sun angle was making it appear as though they were moving. If the flap movements were "intermittent," the plane would have shown different flight characteristics at other portion in the video, not just when the plane finally entered an unrecoverable accelerated stall.
Just my uneducated .02
Here is another one though that does an accelerated stall on a bank (same thing my plane did)
[youtube]http://www.youtube.com/watch?v=pj9bExCIyT0[/youtube]
I am sorry that my (and most everyone else's) opinion (as they are all opinions) do not match up with yours. I don't know why you would say the flaps are moving up and down rather than saying the sun angle was making it appear as though they were moving. If the flap movements were "intermittent," the plane would have shown different flight characteristics at other portion in the video, not just when the plane finally entered an unrecoverable accelerated stall.
Just my uneducated .02
07-10-2010, 03:14 PM
#44
RE: Skymaster Viper ..... unexplained crash??
ORIGINAL: BirdofpraY
Hmm, High speed loop; just look at the impact splash, Easy one to figure out... Now if you are flying the whole flight with a deflected flap for the entire flight this can cause huge loading on a servo and I have no idea of what servos he is using, but I have had 8611's fail with huge loads before. Just ask the 3D guys why they put 4 servos on there rudders. In my 10 years of fly turbine jets I never used my flaps but only to land or take off, or to use in a speed break configuration but never have used them for more than a minute or so at low speeds. It appears the flaps had been deployed in the whole flight. If he comes back on it would be interesting to see if that servo failed or a linkage. If you look at the second video as they bring the jet back the flap is still down but that may just been from the crash. There is still a lot of unanswered questions that need to be answered but other than that all we can do is speculate. I too have lost a few jets so I feel his pain...
ORIGINAL: highhorse
Who says it's a no-no? Who says it was a ''high speed loop''? (everyone else seems to be condemning the guy for being too slow) Who says the servo wasn't a stout, high quality, metal geared unit ? I think it's at least as factual to say that lots of flaps get deployed at higher speeds every day without failure. But that's just my opinion based on guesses
C'mon, y'all. It's human nature, I suppose, to see a vid like this and WANT TO BELIEVE that it wouldn't happen to us (or our wallets and pride) because we are somehow smarter than the guy who was on the sticks. But WANTING it to be true does not make it so...........
Enuff bashing of the poor guy already.
Flaps in a high speed loop that's a no no, so he could have lost a servo during the loop which would also cause the death spiral...(pilot error)
C'mon, y'all. It's human nature, I suppose, to see a vid like this and WANT TO BELIEVE that it wouldn't happen to us (or our wallets and pride) because we are somehow smarter than the guy who was on the sticks. But WANTING it to be true does not make it so...........
Enuff bashing of the poor guy already.
AND now he's also accused of "flying the whole flight with a deflected flap for the entire flight"? In my judgement, which is certainly as valid as yours, there is NO "high speed" flight in evident in this video through the 3rd quarter of the loop.
Another thing to consider, which I think I can safely say IS fact: THE ENTIRE VIDEO IS 53 SECONDS LONG. Since you are now introducing a new theory which involves the "entire" flight in order to support your previous opinion that the pilot was in error for having deployed the flaps, are you in posession of more video than the rest of us have seen? If so, will you please share it with us?
I do whole heartedly agree with the very last potion of your post !!
07-10-2010, 03:24 PM
#45
RE: Skymaster Viper ..... unexplained crash??
You guys who don't fly full scale jets or planes, and do not understand aerodynamics, just need to go up in a full scale plane, as I have, being a FULL Scale Jet Captain of Boeing-727, Hawkers, Westwinds, etc, and see what an accelerated stall does to a swept wing jet! This is exactly the characteristics of a swept wing jet accerated stall. Of course, this manuever in full scale jet is so dangerous, that it is only practiced in a simulator. Both flaps were down. I am sorry to say for the guy, it is pilot error and quit looking for something that isn't there.
07-10-2010, 03:29 PM
#46
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RE: Skymaster Viper ..... unexplained crash??
ORIGINAL: highhorse
are you in posession of more video than the rest of us have seen? If so, will you please share it with us?
are you in posession of more video than the rest of us have seen? If so, will you please share it with us?
No
07-10-2010, 04:16 PM
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RE: Skymaster Viper ..... unexplained crash??
Personally, I just feel for the owner/pilot for his loss! I also wonder if Jan asked the pilot's consent to posting this video here and on You Tube and opening him up to this relentless second guessing and armchair quarterbacking. I also wonder if that laughing voice heard might not be the videographer himself? Makes you wonder why this video was even posted?
Who among us hasn't pulled a dumb thumb at some point which cost us a plane? Would you want it plastered all over RCU and over analyzed and argued about, for however long this thread continues to bleed? At some point this activity just becomes morbid and without soul. Just my opinion. Give the guy a break and stop prolonging the pain.
David S
Who among us hasn't pulled a dumb thumb at some point which cost us a plane? Would you want it plastered all over RCU and over analyzed and argued about, for however long this thread continues to bleed? At some point this activity just becomes morbid and without soul. Just my opinion. Give the guy a break and stop prolonging the pain.
David S
07-10-2010, 04:28 PM
#50
RE: Skymaster Viper ..... unexplained crash??
Hi guys, I tend not to get involved in threads such as this but I am pleased people post their opinions and thoughts on such events. I'm sure we've all lost model jets or will at some point so I feel for the guy. Whatever your opinion as to what happened the event is thought provoking and perhaps by seeing the vidio some of us might think twice about pulling that bit too hard or go and check the linkages on our own models etc... You get the idea.... So maybe posting this here on RCU will save other models from a similar fate.
Just a thought......
Cheers, Alex
Just a thought......
Cheers, Alex