ViperJet1

My Feedback: (12)

Beware.......This will make you sick!!!!!

The guys at the field will tell you how well I was doing with my Viper. 25 flights before today despite the problems that I encountered wich could have been catastrophic .......I seemed to weather through them. Flaps getting stuck due to gap seals catching the trailing edge of the wing(first flight), Rudder desintegrating with the fin at 5th flight and a bit of smaller other issues.Even the strange flight charactheristic this plane seemed to have in slight to heavy wind conditions such as its called "wing walking" , where the plane seems to shift from side to side like your adding slight back and forth rudder even though your not. But nothing could have prepared me for what was to happen today........

At first flight during a high speed pass building up speed at about 150 or more the rudder fluttered wich it had never done before. You heard it. it was loud. My friend Mark heard it. And as I thought highly advised me to land and I did. Under inspection we found nothing really wrong. I pondered over another flight and chose to do so very carefully after his flight. Asking he stand by my side in case he would detect a problem before I do I thought was a good idea.

As I took off the plane seemed to dance a little more than usual but it had always done that somewhat in slight to moderate wind so I proceeded.
As you will see in the video wich I will add was the first video other than the maiden flight, and lucky to find out that a friend had shot it after we got back from the wreckage, I proceeded into my first loop doin two rolls to the top........now.......WATCHCLOSELY!!! That roll at the top was not me as you can hear myself mutter to Mark "I did'nt do that". He said I stalled it and the wind probably blew it over. OK.........But all in all......I felt strange.....like I did'nt have it for a sec.
Moving on through the flight being a bit more concerened I flew even more cautiously and flew a few circuits as you will see and decided to loop it again......
That was the turning point for the plane. At 3:30 minutes into the flight I went into the loop and did not rool at all but as it climbed to the top and overed the loop something happened at that point to initiate an unrecoverable stall. As I realized I did not have control into the spiralI eased slight inputs into the elevator to make sure not to pull full and worsen the stall but to no avail. Even trying to correct with some aileron but nothing helped it.

SIckening at that moment........ it was.....more so of what went wrong. Could'nt tell at the time but it was actually about 1/2 mile away. We trecked up and down ravine's , fell into a mud marsh up to my waste (and nearly sank to my death like quicksand) just to get to the plane while all along its burning away.
As I got to it (still on fire)used my brand new just got Co2 fire ex... on it and still could'nt get it out. Basically we burried it in dirt and then realized it was in fact......A total loss. I only grabbed the turbine to prove that I had a jet to myself.
It even melted the case of the EVO 160.
Perhaps I had stalled it like Mark concluded.............but I can't help but think I have slowed this plane down to much slower speeds and I had not even come near a loss of control like that.

What a gorgeous plane it was. What I pile of ashes it is now.......... Sadened. But I told myself this was inevitable getting into jets. It was only my experience and desire to push through it and the Viper was the plane that caught my eye.
Not sure if others had the same flight characteristics as mine but as I have heard.......they do. I never seen one fly other than my own and youtube.
My friend Nick has one and had his potentiometers go bad on him in flight with his 14MZ.....bad pots........You can take a guess what Iwas using........yes.....a 14mz....but it never faulted before today. I could'nt even tell you if it has the white bad pot in it or not. I just don't know , and I only used for the Viper.
I plan on sending it to Futaba as I don't plan on loosing another like poor major Woody did as I've heard about. Two .........one after another.. If mines a shame,
Thats a crime.
I am uploading the video wich is taking considerable time. So check back in a few to see and give me your thoughts. I would like to hear from ALI and all you guys since you have experience. Unfortunately we will never know for sure what happened. Only me as the pilot knows what it felt like on the sticks, but it helps to conclude some type of majority opinion, Ithink.

What I lost
1 Viper airframe
1 set of viper retracts
1 EVo 160 Booster
1 Powerbox Royal
2 4000 mah Powerbox batteries
1 EV5U pro air unit
7 Futaba BLS155's on all surfaces
1 Futaba BLS352 nose wheel
2 futaba 14 Ch. 2.4 HS recievers
All hangar 9 titanium links
all Dreamworks ball ends
oh yea,
my pilot.
and many other add ons.

15,000$ Give or take.
Heres the video.

http://www.youtube.com/watch?v=FOCzGjDSz7c

FILE IFR

VJ, I'm sorry for the loss. I really like the Vipers too. That sux.

I'd delete the first two paragraphs... George is gonna go postal on you.

Sorry Bro. []

2 RX's too? wow.

ViperJet1

My Feedback: (12)

Who's george?

AndyAndrews

George on the Skymaster Wing Failure thread..

ViperJet1

My Feedback: (12)

Yes , I believe I saw that. And was something I forgot to mention since it is also what could have happened.
Let me say that my wings particularly were very tight to install every time I put them together. If in fact I did loose the tab that were to hold them in I doubt it could have backed the wing out but it had the tendancy of that as I lost it.. But a wing failure? I just cannot say for sure. Maybe you guys can make something out of the video when it uploads in about an hour or so. Check back.

I will not place blame on skymaster. Their kits have issues as all do. I just don't know what happened to mine. I will say Iwas disturbed to say a little when my first rudder blew apart to the faulty hinges they supplied with the kit and the lack of and instructions. And what little ribbing was in the rudder fin. But that seemed to be the only thing I would beef up.
Anton made good and replaced the whole rudder and fin painted free of charge.

It was to my amzement that the plane flew as well as it did with what was left of the fin hanging off it. And even more........I landed it.

dubd

I'm very sorry to hear about your Viper. Did the plane look to be going slow at the top of the loop? Did the plane respond to any of your inputs?

Rush!

Sorry to hear of your loss...   that viper is just a great looking bird.  I think yours might be the second Viper that went into a spiral coming out of a loop. 

Ali posted a while back that the ailerons could get jammed into an extreme throw position if to much travel was programmed into the ailerons.  Something about ailerons getting jammed if there's no enough clearance with the wing?  Could this have caused the slow spiral?  

dubd

The aileron issue was on the small Viper. However, the flaps can get jammed on the large Viper if too much servo travel is applied to them.

ViperJet1

My Feedback: (12)

First I'll answer the flap issue.
The flaps were not on.
The jamming is due to being past 20 degrees of flap the gap seal separates from the trailing edge of the wing. With the lift of air to the underside of the flap it causes the flap to lift up so if you remove from full flaps it can bind one or both. I had this happen the maiden flight and you could tell it tedered to one side but not enough that you could'nt correct it some what easily. I had 15 partial and 45 full as the instructions recommended.
Unless the flap servo went haywire......I find this unlikely. I also ironed the gap sealers down a 1/8 inch with an iron so I would not have this happen again.

As for the aleron getting stuck....I happened to me on the bench. I so worked it out to try and fail it there again and again. After the light sanding it took to get it cleared.
Through the first loop as I said at the top you will see........I had my finger off the stick when it rolled over.
But yes....it is possible it got stuck as a lot of other things are too but I just could not get any feedback to feel it was going to recover.
I have seen the other Viper that crashed and its very similar to mine. Although I did not have my gear down and flaps were not on and I backed off the power coming on the backside of the loop.
Hopefully that puts a little more insight.
Video I believe is done almost............
Ali Helped me a lot with questions on my build and responded quite quickly as I barely even know him. I appreciated that a lot. As this was my first jet.
I bit expensive......but if you watch my maiden you'll see I had little to worry about after hitting the landing the first try. They got even better everytime after that.

http://www.youtube.com/user/viperjet.../0/YsCGdOeejcE

ViperJet1

My Feedback: (12)

Vid loaded
http://www.youtube.com/watch?v=FOCzGjDSz7c

STKNRUD

Oh no....I fear another 5+ page postmortem.[&o]

One thing for sure....it did make me sick to watch. Whatever did happen, sorry for your loss.

George

dubd

The wind was coming from right to left and it appeared you were pulling out of the loop with the plane coming towards you. Perhaps a stall occurred because there wasn't enough lift over the wings since you were flying perpendicular to the wind direction? Do you recall how much power you were giving at the top of the loop?

FILE IFR

Wow.

It seems the rotation stopped for a moment, then continued in the same direction of rotation before it went behind the trees.

Sorry VJ, I've been in your shoes too.

SinCityJets

Gary,

Makes me sick to watch man. I think your initial assessment of a stall is absolutely correct. Stall at the top, followed by a continued elevator pull (not yet realizing it was a stall), than a relax on the elevator which was the pause in the turning, followed by a re-application of the elevator in a last ditch effort to recover the bird before the impact, which re-initiated the stall due to the slow air-speed.

Whatever it was, it sucks. Don't let it get you too down. We all know, that it's not if, but when.

Take care and call me if you need anything.

Chad

causeitflies

The plane would fly slower than that speed, but not while pulling elevator. [] Full power may have saved it and maybe not.
I still feel sick about it...

dubd

I agree. I can slow my VJ down to walking speeds, but I'm not applying much elevator.

DelGatoGrande

My Feedback: (23)

Mike i dont think so[X(] ... havent expirience that stall with mine ither

ViperJet1 sorry for your loss[sm=thumbs_down.gif][sm=thumbs_down.gif]

PHIL GREENO

Sorry you lost your model.
The problem was not your 14MZ as the model flicked out of your first loop after you slowed the model down with an upward roll and you got away with it.
I think you have too much elevator movement. If that is coupled to a CG on the rearward side and remember the Viper has a very short rear moment arm (more pitch sensitive)the model is trying to flick roll on full elevator and slow speed (top of loop)
I have had this problem on my F1 scale pylon racers in the past (high speed flick roll at no 1 pylon)and the cure is to move the CG forward and reduce elevator movement/use plenty of expo.
When you roll inverted how much down elevator do you need to maintain level flight.If you require none or very little down then your CG is at its rearward limit and could come forward a touch to be safe.
I have not flown a Viper Jet but looking at the short coupled design I thinkthe CG and elevator movementcould be critical.

Phil.

rhklenke

My Feedback: (24)

Sorry for your loss - that's hard to swallow, I know.

It may have been a TX issue. However, the pots went bad on my 12FG and when they did, they stayed bad. I sent it back to Futaba and they figured out that it was cold solder joints on the surface mount pots. Lots of guys with that radio I know have been sending them back to have the pots resoldered. I don't know if that has been an issue on the 14MZ or not.

Hind sight is 20/20 for sure, but as soon as you had the uncommanded roll in the loop on the flight, you should have put the airplane on the ground. I know there is a desire to try and figure out what is going on with the plane at that time, but as you saw, that didn't go too well. If you suspected the TX, then checkout flights (perhaps many) with a lesser plane would possibly helped nail it down. In addition, using someone else's TX to fly the Viper for awhile would have been a good test. Of course, after the flutter on the first flight, the second flight probably shouldn't have happened. If you were sure it was the rudder, then the rudder servo should have been replaced and the linkage modified to give more torque at the surface. I have never seen flutter occur that did not damage *something* in the control path and I'd bet that was the case here...

Bob

luv2flyrc

My Feedback: (6)

Sorry for the loss of your viper jet. I'd agree with others here, the most likely cause is too much elevator causing stall.This can happen at any speed. I had it happen to me on skymaster hawk, completely, lost control of aircraft twice on test flight using SUGGESTED elevator throws. Fortunately, recovered and no crash, next flight with seriously reduced elevator, it was a completely different jet!

Mike

basimpsn

My Feedback: (5)

Lateral Balance problem will show-up at slow speed with elevator input.

highhorse

My Feedback: (2)

A very unfortunate loss, to be sure. But this isn't the cause.

Once an a/c has broken ground, steady state winds have no effect on airspeed whatsoever, and airspeed does not change simply because one is flying upwind, downwind, crosswind, or even when alternating between any combinations of the above.

I know that someone here will absolutely insist upon arguing and perpetuating the whole "downwind turn" myth. Please don't hijack this thread. I will start another for that.

ViperJet1

My Feedback: (12)

Normaly you would be correct, but, Being a heli pilot I've got quite quick with responses and running through my head as soon as it was happening was that poor chap that lost his viper in the same manner months ago. I immediately notch slight inputs to the elevator in order to avoid what happened to him.
To no avail. I had full power until the top of the loop wich as soon as it moved over the top I backed off to about 1/4 and the evo is set with a 2 sec spooldown so it should have been adequite. But it was'nt. All in all I have had the plane slower and it never stalled but every situations different.

As Dantley had said about the wind it was actually blowing from the left side of the plane at that point.

I just wish I killed the power to the turbine shorlty before it hit, but I was trying to recover the aircraft as anyone probably would have.

Think I may take a walk out there today and get the mangled mess for something to do since I am off. Because of the extremely rigid terrain of the ARCSflying field it took me a half an hour just to get to the plane wich is probably why ,even though it nosed in, I lost everything.
We had trouble getting the fire out even after exhausting my fire extinguisher.

Bob.......... You are absolutely right about the first uncommanded roll. I should have landed. Its just strange how going slow at the top of the first loop it rolled over that quick. I just felt the wind must have blown it over.

O'well , I won't drag it out, as I hope this thread don't. I just wanted to let you guys possibly learn from my mistake if I made one.
I know it sucks, but we still want to know what went wrong.

I have a Skymaster F-18 brand new waiting for engine and electronics. I know the Viper is big and in order to keep the weight down Skymaster had to lighten parts of the plane so it would seem weak but it really held up fine. The f-18 seems a lot more solid. But its also a totally different plane.
I'll give it another go....in good time. Maybe another viper is in the future.......but not the near future.

Unless I hit the LOTTO!!!!! Ohwait,
I don't play. To much of a risk!!!!!

HAhahahahahahahah.

LGM Graphix

My Feedback: (22)

I'm not convinced of a stall, the nose was pointed down and the airplane heading down before it started to spin from the looks of it. Right before the spin started I don't see the nose pitch or show any evidence of a hard pull on the elevator.
I have no idea what might have caused it, but I know of a few other unexplained Viperjet crashes out there where speed and stalls were not even given a thought.

highhorse

My Feedback: (2)

VIPERJET:

Beware, there is a faction here that will friggin INSIST that you stalled your jet. They were not there, of course, and they were not on the sticks.

But they saw a vid and they will be certain, in spite of any contradictory evidence or anomalies which don't neatly fit their theories, that you screwed up.