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RE: 2 death 4 wounded in model airplane crash - 9/5/2006 9:50:34 PM   
BaldEagel



Posts: 4037
Joined: 10/12/2005
From: Wychling, Kent, UNITED KINGDOM
Status: offline 		Fine no pack drill intended.

Mike

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RE: 2 death 4 wounded in model airplane crash - 9/5/2006 10:00:25 PM   
Woketman



Posts: 3927
Joined: 12/6/2001
From: Slidell, LA, USA
Status: online 		David, I am saying that it is less understood than static strength. Hence our higher fatigue life factor than our ultimate strength factor. Also, in commercial aviation, they get the airframe back to study flight after flight. We never see the effects of flight on the External Tank as it goes to Davy Jones' locker (after being burnt and melted!).

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(in reply to Gordon Mc)
       Post #: 252

RE: 2 death 4 wounded in model airplane crash - 9/5/2006 11:12:39 PM   
EASYTIGER


 

Posts: 7676
Joined: 12/7/2001
From: nyc, NY, USA
Status: offline 		On a similar tangent...I was always very concerned about that B-52 that was built in the UK. You know, the 300 pound one. The second one was only 200 pounds. Both were conventional balsa and ply construction. I know they flew, one had some fifty flights on it...but I was really wondering about fatigue life on them. Weighting the wing down to see what it will hold is one thing. Flexing it up and down a few thousand times to see what happens is quite another. I had real doubts about the methodology used in that model. Conventional balsa model, just larger. Not sure if that is really appropriate with a 300 pound model.
On a most basic level...you take a wire coat hanger and bend it 90 degrees, then bend it back. All looks fine. Do it 10 times and you have a broken coat hanger. And I kept thinking that was going to happen with that particular model. All speculative, of course. I thought Eddie Week's glass and foam approach on his DC-10( which was much lighter to begin with) was much more sound. Any thoughts?

(in reply to Woketman)
       Post #: 253

RE: 2 death 4 wounded in model airplane crash - 9/11/2006 8:36:58 PM   
David Gladwin



Posts: 1885
Joined: 2/5/2002
From: Sydney, AUSTRALIA
Status: offline 		I was flying at a really excellent UK meeting this weekend. I was NOT impressed when a "heads up" call came and I looked up to see a jet model passing overhead minus BOTH of its stab . halves and crashed, inverted, on the 'dead" of the airfield, 50 or 75 meters from the pits. Why? The model, a much vaunted ARTF, did not have its load bearing stab. spar installed at the factory, meaning ALL of the stab loads were carried by the skin and a balsa, butt joined, spar which promptly and not surprisingly, failed ! Structural failure because of abysmal QC at the factory. I was shown, and examined in my own hands, the evidence so no excuses. Another lucky escape before the "big one" which, if this nonsense continues, is sure to happen.

Regards,

David Gladwin.

PS.
All of the BVM ARTFs plus my Bobcat performed flawlessly as well as the Savex's etc.

(in reply to EASYTIGER)
       Post #: 254

RE: 2 death 4 wounded in model airplane crash - 9/12/2006 11:59:01 AM   
Big Tony



Posts: 475
Joined: 10/25/2002
From: Redditch, , UNITED KINGDOM
Status: offline 		David,

Nice to see you at the said meeting . I was acctually calling for the second best bandit flier in the country (your first geoff) when the call came out and also saw the VERY POORLY built and QC tailplane and stand by you with your comments on this and the other threads this was mentioned on.


All the best David

Ant

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       Post #: 255

RE: 2 death 4 wounded in model airplane crash - 9/12/2006 1:36:29 PM   
wojtek


 

Posts: 3017
Joined: 12/25/2001
From: old bridge, NJ, USA
Status: offline
quote:

ORIGINAL: David Gladwin

I was flying at a really excellent UK meeting this weekend. I was NOT impressed when a "heads up" call came and I looked up to see a jet model passing overhead minus BOTH of its stab . halves and crashed, inverted, on the 'dead" of the airfield, 50 or 75 meters from the pits. Why? The model, a much vaunted ARTF, did not have its load bearing stab. spar installed at the factory, meaning ALL of the stab loads were carried by the skin and a balsa, butt joined, spar which promptly and not surprisingly, failed ! Structural failure because of abysmal QC at the factory. I was shown, and examined in my own hands, the evidence so no excuses. Another lucky escape before the "big one" which, if this nonsense continues, is sure to happen.

Regards,

David Gladwin.

PS.
All of the BVM ARTFs plus my Bobcat performed flawlessly as well as the Savex's etc.


David, I agree, BVM ( I personally do not have experience with Savex) quality is some of the best, but it still does not mean that every ARF will be perfect. Hey , remember the king cat boom issues ? I know of at least 5 cases that were publicly disclosed where the whole tails ripped off in flight ... no matter who you get an ARF from, there is always the possibility of flaws / errors, be it in the design itself, material selection, or the assembly process.

In the spirit of not caring about political correctness I will say that the planes I have seen and hear about failing the most in flight have been those from CompArf. Usually the failures i have seen are due to sloppy assembly where the glue joints are inadequate, or poorly asembled. Also, I have seen these come apart after slight dings and scrapes that the pilot disregarded as minor, which ended up being the root point of failure. I would say the old Cermark kits make a close second for in flight failure rates .. the Viperjets are known for the stab failures .. be it poor materials, or poor design, there are issues .. I have seen several MB339s come apart as well from Cermark ( i will say i was happy with mine however, and it survived my abuse for many flights ) Then there are the old Skymaster kits ( from what i have seen, the new manufacturing process SM uses has improved the quality of these greatly and there is a night and day difference between the ARFs of old and what’s being produced now) .. i have seen the occasionally missed glue joint cause devastating failure in flight, such as a friends elevator ripping off due to missing glue in the stab causing the plane to go into the ground.

Bottom line, if you did not build it yourself, you do not know how well an ARF is assembled beyond where you can get at the glue joints yourself. Its a good idea to go over any ARF as thoroughly as possible ...


Voy


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       Post #: 256

RE: 2 death 4 wounded in model airplane crash - 9/13/2006 8:50:35 AM   
David Gladwin



Posts: 1885
Joined: 2/5/2002
From: Sydney, AUSTRALIA
Status: offline 		Hi Voy,

I totally agree with you. We have a problem in our midst and I dont know the answer to it but I do believe it is an issue which needs serious debate before it bites us hard.

At least BVM is taking production back under his own control which should eliminate the sort of problems such as experienced with KingCat booms. A wise move in my view.

Regards,

David Gladwin.

(in reply to wojtek)
       Post #: 257

RE: 2 death 4 wounded in model airplane crash - 9/13/2006 4:18:48 PM   
Eddie P



Posts: 678
Joined: 2/4/2003
From: Reno, NV, USA
Status: offline
quote:

ORIGINAL: EASYTIGER

On a similar tangent...I was always very concerned about that B-52 that was built in the UK. You know, the 300 pound one. The second one was only 200 pounds. Both were conventional balsa and ply construction. I know they flew, one had some fifty flights on it...but I was really wondering about fatigue life on them. Weighting the wing down to see what it will hold is one thing. Flexing it up and down a few thousand times to see what happens is quite another. I had real doubts about the methodology used in that model. Conventional balsa model, just larger. Not sure if that is really appropriate with a 300 pound model.
On a most basic level...you take a wire coat hanger and bend it 90 degrees, then bend it back. All looks fine. Do it 10 times and you have a broken coat hanger. And I kept thinking that was going to happen with that particular model. All speculative, of course. I thought Eddie Week's glass and foam approach on his DC-10( which was much lighter to begin with) was much more sound. Any thoughts?



Hi ET, my personal view is that a wood wing can have just as long of a life (or more) than a light weight composite wing as long as the engineering is sound. Wood is quite basic but it has a natural shock absorbtion quality and the individual component structural strength is very high in comparison. Of course we all know it as the primary product for boats and airplanes used well into the last century. I've flown a few full scale small airplanes with wood wings (well known for their outstanding flying qualities), even the WWII Mosquito was wood and had an exemplary record. Composites tend to erode/decay over time, especially when exposed to sunlight often. Composites used in modern aircraft are extremely different than those used in model applications - they are made via autoclaving processes and heat treated in kilns like pottery - a very specific, expensive and complex process that yields a completely different product. Wet layups for compoosites, like we use, are pre-historic in comparison. Model airplane composites are prone to delamination, viods and weak spots that are difficult to detect in the primitive model building manufacturing processes we use. Composites are on most boats now for the mere fact that they need almost no maintenance like wood and they are easy to mass produce and cheaper. Long term ownership of a wood product, like 20 years, requires some inspection processes but as long as it isn't exposed to too many outdoor elements it should be fine for a very long time.

Now, what is in my garage? Mostly composites. I have a lot of "plastic planes" becasue they fly great, they are light, easy to work with on scratch builds and they dominate the easy to assemble high performance model airplane offerings. Most of my scratch build airplanes are foam core and wood skinned wings with a fiberglass coat over the wings and stabs with a composite fuse - that's just becasue I'm comfortable with the process. If I could exchange a few of my foam core wings for wood buildups, I would however.

(in reply to EASYTIGER)
       Post #: 258

RE: 2 death 4 wounded in model airplane crash - 10/9/2006 2:25:16 AM   
David Gladwin



Posts: 1885
Joined: 2/5/2002
From: Sydney, AUSTRALIA
Status: offline 		The following ASR is offered in the hope it may help prevent a repetition and someone may learn from my mistake:

Yesterday I damaged my beloved BVM F4 (shredded port wing , some fuselage cracks and tears and bent gear, (it will easily be repaired when BVM builds me a new wing and repairs the gear). The AMTNL Pegasus HPES flamed out during the 3rd point of 4 point roll (when the aerial would have been sheilded by the steel jetpipe, possible cause of a momentary FS signal) and the model was landed downwind and off strip. There was NO air in the header tank and the Pegasus has an impeccable record. Preliminary inspection this morning shows that the controlling channel for the ECU, Aux 2 is set to failsafe in the instant "off" position, and so is aux 3, which is a flap channel., BOTH of these channels should be set to hold and inspection of my backup F4 programme shows that this IS the case. How Aux 2 and a flap came to be set to FS on my operating Tx is simply a mystery, particularly as before the previous outing the failsafe function had been checked meticulously (including a double check with Bennie VdG in Holland) and worked exactly as required. I may have inadvertently hit the FS buttons when moving the gear channel to FS, I'll never know.

Downloading the last run data from the ECU reveals the failsafe.

I had seen the JetCat advisory following Malcom Kay's flameout but I knew in my mind that my Aux channel on Pegasus had been set to hold and HAD been checked prior to the last outing, I should have checked again , I didn't recheck and paid the price.

No doubt, my mistake, pure and simple, but perhaps this note may save someone else's jet.


Regards,

David Gladwin.

PS In similar safety vein, I made refernce to the loss of a stab. on a jet model in the UK, sadly there was fatal accident here in Australia last Thursday when a fullsize Strikemaster crashed having apparently suffered separation of its tailplane.





(in reply to Eddie P)
       Post #: 259

RE: 2 death 4 wounded in model airplane crash - 10/9/2006 5:25:47 AM   
CARBUNCLE


 

Posts: 244
Joined: 11/12/2005
From: n/a, AE, US MINOR OUTLYING ISLANDS
Status: offline 		I hope nobody minds if I ask some safety related questions here... Is it just me or did anyone else seem to think there might have been some safety issues that were overlooked at a certain jet event that finished up this week? After looking at certain pics in the thread for the event coverage and reading some posts about situations that occurred, I really wonder if anyone at the event was noticing things that were questionable (to me anyway) as far as safety.. now I'm just asking so don't unload on me.. ok here's my questions - 1st- is it legal or wise to due maidens at jet events? or maybe- hopefully they were done before or after the crowds were there and the official time of the event had not started or was over for the day.. 2nd- is it legal or wise for groups of toddlers (very small children) to be hanging on the "barrier" fence at the flt line (or side of the runway- it looked like) with jets on final in high crosswinds headed right at them? or maybe that was just one of those tele-photo lens illusions.. 3rd- is it legal or wise to have large groups of none flying spectators congregating along the flt line among the active pilots while they fly? or maybe they were all part of the crews.. I know none of us want any accidents to cause jets bad pr and ama relations.. I've heard that the jpolice are watching out for all of us by informing the ama about anyone they even hear rumors about doing dangerous stuff, but I really wonder if some safety concerns that are looked at by some of our "governing groups" are not looked at as closely because it involves someone or some group or some event that is well known and/or the people in question have been flying jets for a long time and are popular or have a lot of friends in the sport... I'm not trying to start a debate here about this one event's safety level or anything else, but if it saves a life then I'm glad to help by bringing it up and maybe to someones attention that could help stop these kind of situations- if these are bad saftey situations.. If these things are legal and wise plz let me know and I'll try to stay more up to date on the rules and not so over worried about safety.. I was not at this event so I can't say I saw anything, but just from looking at the thread I started to wonder about all jet events and if the safety rules are becoming enforced less? or are the officials and groups that can correct safety problems just turning their heads because of who is involved? OR EVERYONE COULD JUST IGNORE THIS POST AND PRETEND THIS STUFF DOESN'T HAPPEN- TILL SOMEONE IS DEAD.

< Message edited by CARBUNCLE -- 10/20/2006 5:09:59 AM >

(in reply to David Gladwin)
       Post #: 260

RE: 2 death 4 wounded in model airplane crash - 10/11/2006 5:09:53 PM   
Ray Davis


 

Posts: 344
Joined: 7/31/2002
From: East Falmouth, MA, MA, USA
Status: offline 		Hey David...always follow your writings...they always seem to be on the mark!

Your ASR above, however: Not sure I understand your thoughts fully, as I'm sure you are aware of US FS requirements....but if I do read correctly, you meant to set up your ECU/engine to 'hold' in the event of ALL FS events. In the US we pretty much subscribe to the thinking that FS' are generally momentary/short term glitches (unless they are truly 'bad', long term events, like a same-channel Tx left on, etc.) and control is restored often w/o the pilot even being aware. 'Hold' is good in that instance/keeps the engine running, but....'hold' also means the engine continues operation in the event of a 'real' FS that would cause an inevitable crash....and likely a turbine-caused fire. (Pretty well accepted after numerous tests and crashes, that if the 'light' is out, even for a second, the turbine cannot be an iginition source.)

Obvious solution seems to be keeping the engine running during short term events but shutting it down for long term....and 'we' 'picked' two seconds as that threshold (thinking that after two-seconds of continuous lost link...it's, indeed, lost!). In fact, it is now codified in our AMA Waiver requirements, '....that turbines must be programed to shut down after two seconds of (continuous) lost link.' Since JR radios have virtually no built in delay, and Futaba only a one-second delay (of lost link before initiating a FS), folks were rightfully loathe to set FS to shut-down w/ either radio system (too many needless deadsticks). So, ECU manufacturers (for US sale, anyway) have programed in a two-second delay if link was not restored on JR systems; one-second for Futaba. Pilots must still program their FS properly...not to 'hold' but to shut-down....and the newer/modified ECUs automagically add that one or two second protection.

This seems to have drastically cut done on burn events when a model is lost due to a lost link, yet enables engine ops after events such as you seemed to experience. (Interestingly, it has also 'trained' pilots of the need to 'flip the switch' just before the inevitable....whatever the cause.) Am I wrong in thinking that's not universally known......or did I just misinterpret your post?

Ray

(in reply to CARBUNCLE)
       Post #: 261

RE: 2 death 4 wounded in model airplane crash - 3/12/2007 12:12:41 AM   
David Gladwin



Posts: 1885
Joined: 2/5/2002
From: Sydney, AUSTRALIA
Status: offline 		So, the discussion on the FJ accident has ground to a halt. However the hot topic in this weekend’s Sydney newspapers is air safety following the death of several Australians in a Garuda 737-400 crash in Yogjakarta and the papers are dissecting the crash in detail and there are many conflicting stories.

In comments about the FJ accident it is clear that a certain percentage of fliers DON’T want to discuss safety in RCU and there is one comment on R/C Freedom (where other aspects of that accident and the pilot’s history are discussed) that we are “stupid” to do so, fearing the bad publicity. There are also a couple of comments on the FJ threads alluding to the opinion that to discuss safety is to “Spoil” the event and another that we should stop discussion as “Frank has you covered”. However I have had a number of highly supportive PMs and emails following my comments on that thread, so clearly many others DO want to discuss flight safety in an open forum, most of those PMs come from model jet fliers with a fullsize aviation connection who know the safety culture which is an essential and intrinsic part of the industry.

Consider this : Every month / week I read a number of fullsize aviation magazines and ALL have a safety element, some with dedicated sections.. Perhaps the most respected world wide aviation industry magazine is “Flight International” which covers everything from GA, military aviation and air transport. That magazine has been covering safety issues as long as I can remember (at least since 1962 ) and does so in an accurate, unbiased and objective way.
It has an Air Safety editor, David Learmount and as well as its regular air safety reporting it also publishes an annual air safety review and from time to time I have seen airliner wreckage on the front cover picture. It tells it like it is and has world wide respect for doing so.

I very much doubt whether David gets any angst from aviation companies (if he does it does not deter him) when he reports and discusses accidents and incidents to their aircraft or equipment and those companies clearly DON’T pull advertising following such discussion, so if its good enough for Flight to discuss air safety matters in public why should gas turbine modelling be different ?

So I ask, as flight safety is an essential aspect of the operation of any and all aircraft, models included, just where and how should safety issues be discussed ?

Please discuss.

Regards,

David Gladwin.

(in reply to Ray Davis)