highhorse

My Feedback: (2)

Why would you be sorry that the views differ. What is there to be sorry about?

I don't know about the "most everyone else's opinion" count there dude, and in any event I didn't kow we were "voting" on the matter. But I think u hit it right on the head when you say opinion. I would not disagree that your opinion is an educated one. So is mine. Nuff said there, lest we start whippin' out our resume's to see who's is biggest.

You make some valid points Chad. I can't argue against them all, nor would I want to. This isn't an all or nothing proposition. In the end, if we only had a magic crystal ball or onboard flight recorder, i suspect that we would both be right and we would both be wrong about various aspects.

As I said, even accounting for various factors, the flap deployment does not appear to be a constant. Certainly, again, the case is not so "clear" as to support the hoisting of this guy by his thumbs. Make no mistake: that is exactly what is going on here, and most of the guys pulling on the halliard are not putting 1/10th the consideration or thought into it that you are.

I applaud your effort in digging up the vid. That is a quite clear case, i think, of loss of lift on one side and resultant crash. In fact, one can plainly see in the beginning of the vid that the thing is quite out of trim with left rudder and right ail trim countering each other. I was only a few seconds into viewing it when thought to myself "oh Sh%t, he's gonna snap left", which he did one turn later.. I had been there, done it, learned from it, saw it coming, and felt his pain when it hit. That airplane had clearly quit flying. (the 104 vid begins similarly then, I think, deteriorates further into a "deep stall", which is a whole other animal)

I don't see that in the subject Viper vid. I see a barrel roll/spiral. I see the exact same flight path as happens during a blown snap when one does not get the inside wing to stall. I see TWO wings still doing the magic Bernoulli thing.

I have seen it my whole life over and over again where folks wrap their popular/easy opinions around scant and/or cherry-picked facts and then throw the whole wad at the pilot's head. It happens in the real aviation world and here in these forums every day.

What I am seeing over and over here is that there seems to be a lot of fratricidal judging and convicting going on based on opinions which are presented as facts, all while the countering views are merely relegated to the status of.....opinions.

I agree completely that there are reasons to initially see this as an airplane stalling and then hitting the ground. But my opinion isn't exactly uneducated, and I see several things that cast serious doubt on that conclusion.

highhorse

My Feedback: (2)

+1

tucson

My Feedback: (1)

I agree Alex.

SinCityJets

HH,

I apologize for my lack of use of BOLD to emphasize my points, however I have seen this in-person by my own wrong doing. One thing I have never understood is why people are so scared to have other people know about their crashes. Heaven forbid someone know that so and so crashed their Viper Jet on landing, or what's his name lost their A-10 due to engine failure, or ol' dude plowed it in during a figure 9. Crashes happen. It's sad, it's expensive, and it's just part of the hobby. No one is calling this guy an idiot, albeit I felt like one when I crashed, but just to nail this point home, when I first crashed my BARF, guess who I blamed......BVM. I told them that a control surface failed in flight, which is what appeared happened to me. I wasn't trying to lie or be deceitful, I really felt an elevator failed in flight, causing this barrel roll to the ground.

I claimed this until someone much more knowledgeable than I explained an accelerated (or high-speed) stall. Not only did he explain it, he PROVED it by taking a plane with a high wing loading, making it a little nose heavy, adding in 50% expo, and inducing one before my eyes (at altitude).

Since this demo, I have done it myself, on purpose, at altitude. It wasn't enough for me to see it, I wanted to know how to get out of it. Unfortunately, the only answer is altitude, relax the elevator, and altitude. Being really high up doesn't hurt either. Without this demo, I would STILL be flying around at 50% expo on elevator (because it makes me fly really smooth) not concerned about relative wing loading and aircraft limits.

These are not digs on the pilot, they are chances for him/her and everyone else reading these threads to learn. If you are flying at a high rate of elevator expo, you are a candidate for this to occur. If you have a nose heavy plane, you are a candidate for this to occur (I am aware of the saying nose heavy planes fly like crap, tail heavy planes fly once.). If you have a plane with a higher than designed wing loading, you are a candidate for this to happen.

Now, one last monkey wrench.....temperature will also greatly affect this (Density Altitude). You may do a maneuver on one cool day, and try the EXACT same maneuver, with the same set-up on a hot day and dump the plane right out of it. I just did this last weekend with my Flash. Bottom of a happy face, a little slow on the down side, pulled hard to get up and do the nose and I saw two dips of the wing. Fortunately, the flash is one of the most forgiving sport planes out, and two dips was all I got, but I have done 1000 smiley faces, but in 112 degree weather, I need to be a little more aware of my speed and control surface deflection.

This is a sad event, but it is also a chance to learn.

Chad

BaldEagel

Can someone explain why having a high expo on elevator makes you a candidate for this to happen? I used to instruct full size and used to demonstrate accelerated stalls and accelerated stall spins and I can't get my head around why having a high expo would make any difference, now if what is meant is too much movement on the elevator softened by high expo that is a different matter, its not the expo that has caused the problem, but the excessive elevator deflection, lets not get this confused if that is what is meant.

Mike

RCFlyerDan

My Feedback: (54)

When you panic, you over compensate on the sticks. Too soft of a center, you keep moving (or jerking) the stick too much until something happens, thinking more is better. As a full scale pilot, you know more isn't always better. On my normal flying rates, I never use more then 10-15% expo, and cut the throws down.

This is why on full scale planes/jets there is a manuvering speed. At or below that speed, full deflection of the control surfaces won't cause structual damage or failure. Above that speed, you are asking for trouble. Same on a model.

SinCityJets

Sorry for confusing you Mike. Dan nailed it. High expo, pulling through the turn, pulling a little more, just a little more (reached the point in the expo curve where my "little" pull produced a LARGE movement, exceeding the allowed control surface deflection. While the expo itself is not the root cause, the dummy pulling the stick (aka ME) more and more, can be.

Chad

highhorse

My Feedback: (2)

Yup, that last "little bit" on the stick is actually a LOT at the elevator, and there is no force feedback to warn you.



Chad, we are chasing each other's tails, and I'm worn out. The best we can do is agree to disagree on the cause of the crash in the vid and many of the subsequent posts.

I have read ur posts on many other topics, know something of ur background and respect your knowledge base. You are a reasonable, intelligent, and accomplished dude.

But I think you are mistaken here, on this topic vid, in this thread.


It's Saturday night, bye Y'all...............

SinCityJets

HH, I always appreciate a good debate based on what each believes to be the facts I appreciate the comments and feel the same way of you. I too, hereby agree to disagree.

Chad

RAPPTOR

My Feedback: (41)

PLANE BECOMES MORE NOSE HEAVY WITH FLAPS DOWN.C.O.L ,MOVES REARWARD.. TOTAL STALL FROM TO MUCH ELEVATOR!!! SAME AS TOP OF A LOOP.. THIS ONE WAS AT THE BOTTOM !!,,

Gary Arthur

My Feedback: (29)

To me, it looks like the loop was done with the gear and flaps down. As someone has already mentioned the left flap looks down but if you look at the right one, it looks up. Could a servo or linkage have failed on the right flap?

aatiger

My Feedback: (26)

Hello All,

Great discussions and investgative work by the vey best jet pilots around, learn lots from these 3 pages, ultimately, we draw our own conclusion to what actually happened.

I do like to ask the pros ( I'm sure many new jet pilots would like to know as well) that are there many other moves like accelerated (or high-speed) stalls we should be aware of
what not to do or watch out for?

SM Viper jet suppose to be easy flying jet, could accelerated stall happens to any jet?

Allan

norbert montenegro

Hi Allan,
I have a Viper SM with more than 115 flights, without any problem, however schedule a series of acrobatic figures and always do the same motions, I can ariar in one or two figures, but it is always the same and always what I do with the model.

The rest think it is wishful thinking, there is an aggressive use of elevators, low speed and the landing gear out, and looping with thIS condition. UFF !!!!!


Norbert

SinCityJets

I am certainly not one of the pros, in fact the opposite is probably true, but just remember, an accelerated stall can occur in ANY maneuver in which the pilot pulls too much elevator. Whether it's a bank, an Immelmann, a loop, or a cuban, an accelerated stall can occur at ANY speed. Operate the plane within its limits and don't grab too much elevator (pull too many G's) on your maneuvers.

Seacrest, out!

norbert montenegro

And the Landing gear out. It is a great aerodynamic brake.
Again, I have a Viper with more than 115 flights and no problems but I do loops with the landing gear out.
Norbert

aatiger

My Feedback: (26)

Great Pointers Chad, thanks

gonzalom

My Feedback: (1)

It sounds nuts if he tried to loop at low speed, low altiitude gear down and flaps down....... If that was intended..... I don't what to say.

Gonzalo

David Jackson

My Feedback: (15)

Deleted

jfetter

I'm new to jets, been flying prop planes some 7 years but jets only a little more than a year. My instructor, Rob Lynch, who is working to make me a respectable jet pilot very early on had me take my Electra up high and point the nose down. On the way down he said pull back on the elevator, hard so I did. Wow! I wasn't expecting it, I had never seen it but bam, there it was, high speed stall to the heavy/weak side, happened in an instant and resulted in the same death spiral as the video. Even myself, watching this video for the first time, recognized it, it was that last tug of the elevator, probably becasue the pilot feared too low of an altitide to complete the loop, clear as day...

Jack

BlueBus320

My Feedback: (57)

20+ years of rc, 20yr chopper pilot, 6yr turbojet airline pilot.. All my aviation experience tells me: If you think you know it's an accelerated stall, you don't!!! Without some sort of a flight data recorder to tell you exactly what that plane was doing, it's all just guesses. I would personally trust a high time rc Jet pilot on what happened by looking at a video, over a full scale pilot anyday. We recover from them every 6 months in a sim, but the experts on what they look like are the rc guys.
IMO. No one should clame to know what happened, because the only fact here is, You Don't.

Robrow

I teach aerodynamics amongst other things but it is difficult without the aid of flight data to say exactly what happened.

A similar thing happened to me some time ago flying a Rookie II, took me completely by surprise, it started rolling around it's velocity vector, (same position during a loop), but fortunately as I eased off the back stick it recovered in time. Maybe it was helped by being a delta with foreplanes and no gear down, I'm not sure but since then I have always given that area of the flight envelope plenty of respect and touch wood it's never happened to me since.

Rob.

Springbok Flyer

Hi guys,

Perhaps a good time to throw a few facts and onsite speculation into the mix.

Facts first:
- It was not my plane.
- The radio was set up with failsafe.
- The pilot was having some retract problems and all the retract movements you see in the video were made by the pilot.
- The plane was not flying at altitude, but basically at sea level.
- It was not hot, the temp was around 18c.
- The pilot is well experienced in jet flying - I've known him since 2004 when he had been flying them for some time already.

The onsite speculation:
- After the crash there was a conversation, in my presence, between the Viper pilot and another pilot that concluded the following situation.
- The second pilot said that at the exact time of the incident, he was switching on to fly his own jet. The radio would not bind.
- Both pilots were using JR 2.4 Spectrum equipment.

Therefor as the person, posting the video on YouTube stated in his comments - suspected radio interference or failure.

Cheers

Jan

norbert montenegro

Radio interference????
JR 2.4 Spectrum equipment???

Norbert[sm=shades_smile.gif]

BaldEagel

The difference between a Sim and the real thing is when you pull back on the elevator at high speed and quite suddenly you are upside down and in a spiral dive you know its an accelerated high speed stall, you can't feel that in a Sim, the best flight data is the seat of your pants.

Mike

norbert montenegro

Hola

I still think it is a misuse of elevators, do not think that radio interference. Excuse my English is not very good, and if I offended anyone, sorry.

Just my opinion for the video I've seen several times and have and fly, the same model.

Saludos
Norbert