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Old Sep 16, 2012, 07:28 PM
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Originally Posted by sighen View Post
...and as such, should be flown in that manner. That means, if the original is not intended for aerobatocs, why should you try that on a model? Just becaus there are videos on Youtube showing consecutive loops? In my opinion, this is a glider intended to thermal, which it does really well. I had my maiden flight on it yesterday, without any reinforcement, and it was really nice to hear the hight gaining sound from my variometer. In few minutes, I went from 350 meters to 420. The second trip was also very nice. I think that a lot of people tend to fly scale models on a non scale manner, often with bad results to the model. That said, I too belive that there are "lemons" amongst products, as is the case with many products.
However, I think it is unwise to fly a scale model in a none scale manner. Before buying a scale model, one should read about the full size counterpart and see what it is intended for, and capable of. And, not least, the don'ts. Besides this glider I fly a 1:3 Grunau baby (4.5 meters), a 1:3 Minimoa (5,5 meters) ASH 26 (4,5 meters) and a ASW 24 (4 meters). I try to fly them in a scale manner, and have never had structural problems with either of them.
I'm sorry, have you not read this thread? Have you not looked at the pictures? Have you not seen the size of the so called spar? Mine is grounded until Hobbico comes up with a fix and if that fix is not adaquite in my estimation I will do my own repair to add a real spar to the wing. How these are still flying is beyond me......the spar system they have used may be suitable for a 2 meter plane, but a 6 meter 35 lb. airframe? No.
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Old Sep 16, 2012, 07:41 PM
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Sighen,

I hope and pray that your plane holds together flying in your scale like manner. My plane broke because the spar was inadequate for this size of glider. Just know if yours does break and you injure or kill someone as a result your argument that you were flying it in a scale like manor will not save your you know what. Like I said I hope yours stays together for along time.

See Ya,


Pat
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Old Sep 16, 2012, 08:26 PM
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The existing joiners

I have had a look at the existing joiners.
.469 Diam Carbon 2 off for the tips
.469 Diam Carbon 2 off at the root
1.25 in .035 Al Alloy at the root. This assumes it is not soft Al.

The joiners themselves are up to the task.
The issue is transfering the load to wing structure then having that structure strong enough.

Allan
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Old Sep 17, 2012, 02:58 AM
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Originally Posted by Big Nuts 181 View Post
My ka8 flys in a bery scale manner and does beautiful loops and stall turns in a very scale manner. Remember these were a club aircraft intended as a follow on from the ASK 13 trainer and were rated for light aerobatics..... Loops spins etc and were built to survive a winch launch as a cost effective alternative to the more expensive racing class kind of like a 1-26 Schweizer. just as many are today..... Not all though mind you.
If you look at the fullsize manual, you will see that the original is nonaerobatic, it is not intended for such maneuvers. Performing them would overstress the airplane and could be fatal.
See http://www.csgc.org.uk/Manuals/Ka8%2...t%20Manual.pdf
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Old Sep 17, 2012, 03:16 AM
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Hi Pat and Szd16,
I can assure you that I have read all 400+ posts in this tread, and I am aware of the limitations in the structure, and I have looked at all the pictures. Of course I will monitor this tread to see what solutions or modifications Phoenix Models comes up with.
However, this is a thermal flying glider, and as the full size manual states, it is nonaerobatic. I should not be flown at high speeds. The original manual states max 60 mph in tow, and the flying speed is not high, either. I think this also should be applied to flying the model. In my opinion, it is misleading from the producer to show consecutive loops when the glider is nonaerobatic. It can lead buyers into flying the model too hard.
I bought my model in Norway, and will of course see if similar cases turns up in Norwegian forums.
(being a Norwegian, my English language may not be correct at all times, but I hope that you understand my postings).
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Old Sep 17, 2012, 03:29 AM
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Originally Posted by pmccleave View Post
Sighen,

I hope and pray that your plane holds together flying in your scale like manner. My plane broke because the spar was inadequate for this size of glider. Just know if yours does break and you injure or kill someone as a result your argument that you were flying it in a scale like manor will not save your you know what. Like I said I hope yours stays together for along time.

See Ya,

Pat
Hi Pat,
Of course I am not interested in crashing the model as a result of weak structure, possibly injuring people or property. That said, I think it is unnessacary to be sarcastic about my flying manner. The model had an incredible flight picture when it soared very slowly overhead, picking up even small thermals.
I am very interested in how many modellers have suffered problems with the wings, to see if there are a few lemmons, or if it is a common problem. Being very low priced for this size of model, I think that it will be sold in large quantities.
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Old Sep 17, 2012, 09:58 AM
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Ok.....we are all entitled to our opinions but not to our own facts......and the facts are is that this airframe is woefully under designed for its size and weight.
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Old Sep 17, 2012, 10:18 AM
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Yah but works as long as your not a hack .......

:-)
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Old Sep 17, 2012, 10:34 AM
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Originally Posted by sighen View Post
Hi Pat and Szd16,
I can assure you that I have read all 400+ posts in this tread, and I am aware of the limitations in the structure, and I have looked at all the pictures. Of course I will monitor this tread to see what solutions or modifications Phoenix Models comes up with.
However, this is a thermal flying glider, and as the full size manual states, it is nonaerobatic. I should not be flown at high speeds. The original manual states max 60 mph in tow, and the flying speed is not high, either. I think this also should be applied to flying the model. In my opinion, it is misleading from the producer to show consecutive loops when the glider is nonaerobatic. It can lead buyers into flying the model too hard.
I bought my model in Norway, and will of course see if similar cases turns up in Norwegian forums.
(being a Norwegian, my English language may not be correct at all times, but I hope that you understand my postings).

Well there you go I didn't know that I thought they were rated for loops.
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Old Sep 17, 2012, 11:02 AM
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I was not being sarcastic about your flying. I was just stating that this plane is under built and it is known to be under built. Anyone that is still flying one until either they put together their own re-enforcement plan or wait for the MFG to correct the problem is doing so at their own risk and the risk of others. I truly hope that there are no more failures period. It is a very sick feeling seeing your plane falling helplessly to meet it's demise with Terra Firma. Like you said the plane is beautiful in the air and though my flight did not last long, appears to be a really great flying plane. I hope a solution can be offered and we can all enjoy the plane for a long time. The further I tear into my damaged wings and look at how this thing was constructed there is a very little doubt that the person that was building wings the day mine was built was having a bad day. Not only is the structure inadequate for this big of a model but there are several glue joints that were very lacking in enough glue to form a good bond between pieces of the structure. Oh and just for the record, the stresses I put my plane in before the wing folded would not have been sufficient to even remotely warrant to be considered excessive. I have seen many incidents on tow that would have stressed the plane a lot more than what I did. Did I get a lemon? Probably, but the failure of my lemon had uncovered a major issue with the design structure of the spar system. The carry through and wing joiners held up great, but the spar is not tied into any of the joiners thus creating a shear point at the point where the joiners end. Guess what, that is exactly where mine failed. Good luck with your model, I hope it stays flying for years to come.

See Ya,


Pat

Quote:
Originally Posted by sighen View Post
Hi Pat,
Of course I am not interested in crashing the model as a result of weak structure, possibly injuring people or property. That said, I think it is unnessacary to be sarcastic about my flying manner. The model had an incredible flight picture when it soared very slowly overhead, picking up even small thermals.
I am very interested in how many modellers have suffered problems with the wings, to see if there are a few lemmons, or if it is a common problem. Being very low priced for this size of model, I think that it will be sold in large quantities.
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Old Sep 17, 2012, 04:15 PM
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Wing is currently good for about 2G

I have enough info now to get a feel for the current wing.
The numbers suggect it will rupture at 2G. That assumes the loads from those joiners find their way to the spars and the D Box AL Alloy tube. Their are lots of variables in all this including how well things are glued and assembled.
This explains why many are surviving out there for now. Flown with care at 1G plus minus 0.5G it should work.

Please, I recommend no one try a loop or fly a tight turn much above minimum speed, at least not over a populated area. Watch for wing damage on firm landings too.

Unfortunately the beef up will have to extend the full tength of the inner panels and about 8 inches into the tip panels to get that 5G we are aiming for.

You have the wood and carbon strip dimensions for a full single main spar replacement in my earlier mail if you want to go that way. The current center joinrs are up to this load if you can tie them in properly. Otherwise a big single joiner in line with the spar is definately the best.

I'll get on this week and sort out the carbon tube method

Fly carefully

Allan
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Old Sep 17, 2012, 09:29 PM
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I was one of the tow pilots at the Mickey Sullivan aerotow where Pats plane went in. I was walking to the hangar to get fuel for my towplane and watched Pats wing depart the airframe. I had a side view of it and the nose dropped slightly and even before the fuse became level , the wing came off. From the view I had, the plane was not moving very fast at all. I know the plane was going faster than it looked , but there was no abrupt elevator movement, the wing just came off and the rest is history. After looking at the wing construction, Im suprised it survived the tow.
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Old Sep 17, 2012, 10:13 PM
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I guess that shows how really marginal this model is, particularly if you get one like K2K's on page 19. Voids in the ply and parts only partially glued. All this degrades that 2G capability I was talking about.
Turbulence too can impose a lot of load on a big light model. With real ones will apply a thing called gust factor to the loading spectrum. This has a lot of influence particularly on big lightly loaded structures like this. Pat may have got caught with some rough air too.

All this says the only safe thing to do is park until you have a better wing, either by fixing your own or getting an improved wing from the manufacturer.

Good luck all.

Allan
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Old Sep 17, 2012, 10:35 PM
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webs?

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Originally Posted by AllanK1 View Post
I guess that shows how really marginal this model is, particularly if you get one like K2K's on page 19. Voids in the ply and parts only partially glued. All this degrades that 2G capability I was talking about.
Turbulence too can impose a lot of load on a big light model. With real ones will apply a thing called gust factor to the loading spectrum. This has a lot of influence particularly on big lightly loaded structures like this. Pat may have got caught with some rough air too.

All this says the only safe thing to do is park until you have a better wing, either by fixing your own or getting an improved wing from the manufacturer.

Good luck all.

Allan
Allan, Is the 2G capability figured with the existing webs, WITH the triangle holes in each, as they are now, which only gives a small portion of each web directly connecting the caps in each bay, OR is the 2G figured with the wing as is, but with the same webs, WITHOUT the large cut-out triangles, as is usually done in a proper spar assembly? In other words, to have an actual 2G load capability for the box-stock wing, do the existing webs with the holes, have to have web doublers to make them solid? Were the web triangle cutouts figured in the calculations? I'll definitely add web doublers, but It just makes me wonder if the webs hadn't had those large cutouts for assembly, if the wing would have failed so easily. Thanks for all your time and work.
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Old Sep 17, 2012, 11:43 PM
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Webs OK as they are.

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Originally Posted by flyingfever View Post
Allan, Is the 2G capability figured with the existing webs, WITH the triangle holes in each, as they are now, which only gives a small portion of each web directly connecting the caps in each bay, OR is the 2G figured with the wing as is, but with the same webs, WITHOUT the large cut-out triangles, as is usually done in a proper spar assembly? In other words, to have an actual 2G load capability for the box-stock wing, do the existing webs with the holes, have to have web doublers to make them solid? Were the web triangle cutouts figured in the calculations? I'll definitely add web doublers, but It just makes me wonder if the webs hadn't had those large cutouts for assembly, if the wing would have failed so easily. Thanks for all your time and work.
It should do the 2G with the out of the box wing. The cut outs in the Webs are OK. They should still carry enough shear between the spars as they are as long as they are glued fully to the spars. This is important as the provide stability and prevent compession buckling.
This is still a perilously week structure though.

Allan
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