A Shadow of its Former Self
I am posting this due to the manufacturers determination that it was not a defect from manufacturing that caused the in-flight failure. I have had a number of qualified designers, engineers and professional builders look over the evidence and everyone has agreed that this was indeed a manufacturing flaw. Due to the fact the manufacturer will not replace or compensate me in any way for the loss, I feel it is my place to show other modelers the evidence, the emails and let you the reader, decide if you want to purchase from a company like this. Just because they are located over-seas and not bound by any of the business laws or recourse, read this as they can not be sued, that we have in the USA, they feel they are immune from standing behind a product. This is not a cheap over the counter model, this is a world class FAI F3A competition model. I will let you decide. If you feel my case is just, all I ask is please refrain from purchasing any products from Technohobby based in the Ukraine. They will get the message.....
I do feel that noel Barrett, the distributor, did what he could to resolve my issue. My quarrel is not with him but with the airplane manufacturer.
I purchased 2 used Angels Shadows several years ago and have been contesting them ever since. I really like the way they fly and the finish is great too. About the time I purchased my used Shadows they changed the wing, increasing the taper on the trailing edge, decreased the span, all to aid snap maneuvers. I really wanted two sets of new style wings but on April 15th of 2006 I made an agreement to purchase a new Angels Shadow via Noel Barrett in Ireland. Noel is the world distributor for the Angels Shadow. According to our emails the plane had been a "cancellation" and just became available. To me this was good news, as there was a four month wait for a new plane production slot according to Noel. I placed the order and prepaid the entire amount at their request in good faith that this was a newly produced model and was built for a YS engine. The model arrived via air freight in Chicago. I had no problems with customs and the package had no apparent damage. With freight the price of the plane was very close to $2800.00 US dollars. I assembled the aircraft with all new MK, Tettra and CH hardware. I installed my trusty YS 140DZ with Hatori Muffler for power. A Hyde mount and permanent nose ring were already installed by the manufacturer. As are most Pattern pilots, I too, am very anal about my setups and what equipment I use. I will not detail the test flight here as it is in my email below.
The General Consensus:
I have had several nationally known pattern plane designers, an aerospace engineer, a few professional builders, including a composites expert who builds RPV's, look at the actual wreckage and they all agree that the fault lies in the material that was used as a stiffener in the rear of the fuselage. It is a very soft Depron foam that was adhered to the fuselage side with one bead of an epoxy like glue. The glue held to the fuselage, but the foam did not hold to the glue. The Depron was not laminated with glass or carbon fiber. It was just plain foam. The general consensus is that possibly even before the airplane was shipped to me it could have been partially separated, however the problem surfaced during the knife edge part of the test flight, starting from the front left side, the foam delaminated from the fuselage, thus allowing the fuse to "oil can" and collapse causing the vertical and horizontal surfaces to flutter and the in-flight separation of the complete tail assembly. This was not flutter of the control surfaces, this was the actual surfaces aka, horizontal and vertical stabulators themselves. Despite the claims of the manufacturer, the evidence does not support "rudder flutter". Especially when the rudder is aerodynamically balanced and the rudder servo was completely intact, the gears were not stripped and the control wheel was still attached. The cables showed no sign of failure had been "cut" at the adjustment screw on the control wheel when the tail separated from the plane in flight.
It has been the consensus of everyone that has seen the parts that if the Depron foam stiffener in the tail had been laminated with e-glass or carbon fiber, the separation would not have occurred. It was the oversight of this small, but vital step, that created this in-flight failure. In the USA we call this kind of "oversight" a manufacturing defect.
Here are the inside fuselage shots of the foam stiffener in question.
You may notice in the fourth photo the Depron reinforcement on the turtle deck which IS laminated under glass cloth, which is the correct way to use this type of material as a stiffener.
I have had my other Shadows for several years and have been very happy with them. The construction methods, while similar, does not use the same materials in the older production runs. The two I have, number 24 and 30, are framed with vertical balsa crutches in the aft end of the fuselage for stiffness. I am not sure when they started using foam, but if any of you have Angels Shadows built from 2004 until now I would inspect this area before further flight. If you find the foam in the same state, not laminated in any way, I would not recommend further flights until the foam is laminated with glass or carbon fiber to prevent separation of the bonding and possible total in-flight failure of the empennage. They may have started doing this when electric powered Shadows came on the scene.
I setup all the control linkages in the new Shadow identical to the other two. Below is an email of the details of the maiden test flight that was sent to Noel and forwarded to Vladimir. I have also included his email response and my counter response. Notice that he says the model was built in 2004. My question is if he is 4 months out on production why did he have this old warehouse queen around in the first place and second why were they not up front with the production date and age as I still paid a premium price. UV and other environmental concerns may have had an impact on the plane in storage. There are just to many factors on the Russian side that make this plane a total question mark. I have given Technohobby plenty of time and even volunteered to ship some or all of the remains to them after my full documentation. His whole response was based solely on a few photos and my email.
My Email to Noel Barrett on June 1st 2006 just a few hours after the in-flight break up.
Noel, I just returned from the first flight of the new Shadow and it did not go well to say the least. I lost it to an in flight break up that started at just in front of the horizontal stab. My first flight was witnessed by three others and they will confirm the events if necessary by sworn affidavit. Here is the details of my setup: I set it up just as my other two Shadows with the same throws (7 degrees of aileron and elevator and about 28 degrees of rudder). I used high quality servos, Futaba 9650’s on Elevator, Futaba 9154’s on ailerons, a Futaba 9151 on the rudder and a 5101 on the throttle. I was running my 9ZAWII with a 309 receiver and a regulator set to 5.1 volts with a 6 volt nimh battery pack. The engine was a YS 140DZ with a CH hobbies header and a Hatori 698 muffler. All hardware was MK and Central Hobbies. I had a tetra fuel tank. The prop that I started with was an APC 16X12 which is the same setup I used on Shadow #24. I had inspected the outside of the aircraft for damage after picking it up from Swiss Air and I found nothing that would indicate any shipping damage. My balance point was the 225mm that we had discussed and was verified by the flight test. The flight test: The conditions were as follows: Temperature 74 degrees, wind was out of the North at 5 mph. Our field lays North-South. I had run the DZ prior to the trip to the field to set idle and throttle curve. I fueled with PowerMaster 30% DZ fuel. After a startup and run up to set the high-speed needle I taxied out. The plane departed as normal. I noticed right away it flew very similar to my other two shadows. I performed a 90 degree turn out and a 270 to down wind for a trim pass. It took only 2 clicks of right aileron for hands off flight. I did a ½ Cuban 8 and did another straight and level pass. On the North end I pulled for a humpty bump with a half roll on the up line to check vertical up and down lines. On the down wind pass I rolled inverted to check the CG and it took just a scoch or a touch of down to maintain straight and level so the 225mm CG was right on. I rolled out and pulled to a reverse Cuban 8. On the up wind I rolled inverted and checked the trim again. I once again did a ½ Cuban to downwind and did three rolls to check for my aileron throws and if I was going to need any additional differential, I had setup for 7 degrees up and 5 degrees down which is the same I am using on my other two. It was axel and on line and no correction was needed. I did a humpty bump and on the up wind I rolled left to knife edge and held it level for a 6 count. No rudder to elevator mixing was needed. I did another ½ Cuban 8 and headed back down wind and rolled right to knife-edge and held a level line for a six count. All this time I was varying throttle as needed for each maneuver and I only needed about 5/8 throttle for straight and level. At the end of the six count I rolled level to setup for another turn around when, at ½ to 5/8 throttle, I noticed a slight tail wag. I started to reduce throttle to idle but before I could the amplitude increased exponentially and the tail separated ahead of the vertical and horizontal stabs. The fuselage with the wings attached headed towards the ground as the tail parts floated down landing beyond the fuselage. We walked out and I photoed the crash site. The fuselage had impacted in a nose down attitude into black farm dirt. The spinner was about 6” in the soft ground. The lightened back plate was bent. As you will see from the pictures there was nothing really left intact except for the tail. Noel, I have been flying RC for 27 years and it has been at least 15 years since I have had a serious crash. I have been flying pattern since 1995 and compete in the AMA Advanced class, so I do know what I am doing. I would be the first to admit if I had done anything wrong. I have owned and flown Angel Shadows number 24 and 30 for the past two years competing at the district level. I used one of my existing Shadow setups in my 9ZAWII as a starting point since Ivan Kristensen did the trimming and setups for both of my other two Angels. I checked and rechecked all my throws and settings and I cannot find anything that would have caused this kind of catastrophic failure on my end. There had to be some kind of problem in the airframe. This should never have happened on a gentle test flight. I did no snaps, no outside anything…….no hard pulls….. The airframe is a total loss. Only the gear legs survived. All of my servos will need repair and the YS has a damaged fuel regulator. The exhaust system except for the header is a total loss as is 70% of the hardware. I figure just in repairs to what I installed I will be in excess of $900.00 US Dollars. I don’t know if Vladimir will want any of the structure back to see where the failure occurred and why. But I can ship what is left if necessary. I have not emailed anyone or posted any information to the pattern boards and I will not until I hear from you. I would hope Vladimir will stand behind his work on this one. The total time of the flight, well you add it up I was in the box the entire time…. Maybe 7 to 10 minutes at most. If you need those witnesses I can either have them contact you or have them send you their observations. They were all dumbfounded, a in flight breakup during straight and level flight. One of them was a Russian (Yury Brandt) was from the Ukraine and lived not far from Vlad’s shop. He was shocked and completely surprised by what took place today. I was to go to our first district contest this weekend and was simply going to use the new Shadow as a backup to #30. There is no way I can get #24 back together in time with the damaged engine and exhaust so I will cancel this weekend and our district shoot-out next weekend. My season is turning out to be just terrible. Please forward this to Vladimir along with the photo’s. I will await your reply. Thanks, Marty King
Here is the reply from Technohobby on June 3rd, 2006
Dear
Noel and Marty.
Yes,
it is very sad news. I am shocked.
I
understand as it is awfully to lose the plane.
Accept
my condolences please. It is very a pity to me that such has taken place.
I
have closely studied your letter and pictures.
Thank
you for the detailed description, I see you are
accurate
and punctual person.
What
do I think about happened?
It
should not happen because of a mistake of a design of model.
Models
made before and after this model successfully fly now. It is about 150 models.
Probably
you know that in 2002 there were problems with forward edge of wings and the
stabilizer.
It
was more than 30 models up to your plane. Your model was made in 2004.
I
have improved a design of seams of wings and a fuselage.
Such
case was not with similar models which have been made before and after this
broken model.
The
design of models was absolutely identical. I have toughened the control over
quality of works.
I
have working book where parameters of a material of which the model is made are
marked.
In
this book it is written down - what, when also who made the work.
I
should to tell that fuselage of your
model made very much responsibly and accurately under my supervision.
I
do not believe in any miracles and accidents at manufacturing model.
If
there are mistakes which I has not noticed in a design or in manufacture of
models it would necessarily be shown on other models.
But
I did not receive any news about wreck of models.
For
example, Luca Friggeri from
I
see the real reason resulted to destruction of a tail of model - flutter of the
rudder.
The
reason of fluttering of a rudder can be a detachment or the big easing of
rudder’s cables.
I
cannot find more reasonable explanation that happened.
I
understand that you
are
the sportsman with experience. But as shows
the
practice, nobody is insured from mistakes at installation of equipment. Among
the Russian sportsmen of such examples is a lot.
I
very much regret about happened.
If
I had big company with manufacture more than 100 models for one year, I not
doubting make the new plane for Marty is not dependent on the reasons of crash
the model.
But
I can only offer you the big discount for new plane if you will want in the
future.
I
understand that is probable you will be dissatisfied but, unfortunately, I
cannot make another.
I
am sorry.
Certainly
you can describe this accident on the Internet. And it is very unpleasant and
not good for me.
You
are able to do it.
But
you should understand that I can tell my opinion in this case too.
I
sincerely hope that we can do without it.
Best
regards.
Noel, I disagree with him on this as I have the same rudder setup on my other two Shadow and I even have a cable tension meter which I use for full size aircraft and I use that to make sure the new Shadow had the same tension on the rudder cables. I understand that he is unwilling to replace the model, so be it. I will not order another. I still say it was not a design flaw but a delaminating of the skin on the left side if the fuse which caused the entire episode. Composite ARF has a similar thing and at least they replaced the aircraft. If he was located in the US we would be having a longer discussion. Since he is out of our country I have no recourse to either prove my theory or disprove his. I bought what I thought was a newly constructed airplane. Now he says it (number 113) was built in 2004. That my friend it over two years of sitting and way in excess of any manufacturers warranties for most any product. I am not happy and I do know Shadows. Not as well as the designer but I fly and maintain two of them. Again, I purchased what I thought was a newly built aircraft and not a two year old warehouse queen. I think I will have to look at the Pinnacle real close. Thanks, Marty
Again, I post this for you the reader to make your determination as to whether to purchase anything from Technohobby in the future. Again, no one is perfect and manufacturing mistakes do happen. Unfortunately in my case I am out a plane and $2800.00 hard earned dollars plus the damage equipment. Thank you for reading this and if you would care to make a comment send it to mking46516@yahoo.com