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Old Jun 09, 2009, 04:58 AM
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Tuomo's Avatar
Jyvaskyla, Finland
Joined Aug 2003
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Quote:
Originally Posted by jojoen
...But one thing many do not think about is also how this can happen. If you land nose in hard the joiner box can break loose. this is then easy to see in many cases as skin will get wrinkeled in very specific places that will not happen in a launch. So if you have damage of skin from landings you might see a failure like pictures have shown. This can happen to many models since spars is not made to be strong forward/backwards.
Just an input..

I have already those damages on my nr.1 model because I always land hard and had one hard one... So I will not claim anything if that model fails.
The joiner design used in Perfect, Apspire and many other moder planes snaps under extreme fore-aft loads. With my Aspire I broken 3 or 4 joiners, allways in a crashes (and maybe once in a very hard landing). Never had any damage to spar or wing skin close to spar.

A pic linked from Samba www-site:


What kind of joiner does Exprlorer use?
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Old Jun 09, 2009, 06:56 AM
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Sofia, Bulgaria
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Here I posted joiner of my Xplorer.
I fly Xplorers near 1 year and 4 months, fortunately have no crash (only small repairmen of fuselage after high speed landing for wind in North Cyprus).
F3j models are nor produced for F3B style launches, they are lighter and because of this not so tought. Also hard F3j landings are very stressful for all airframe and this gain cracks in structure. May be not all pilots think about this and sometimes failure happen.
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Old Jun 09, 2009, 10:00 AM
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Norway
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Quote:
Originally Posted by Tuomo
The joiner design used in Perfect, Apspire and many other moder planes snaps under extreme fore-aft loads. With my Aspire I broken 3 or 4 joiners, allways in a crashes (and maybe once in a very hard landing). Never had any damage to spar or wing skin close to spar.

A pic linked from Samba www-site:

What kind of joiner does Exprlorer use?
If you can can find ANY Perfect joiner that have broken on landing I will be VERY surprised. I have not heard of any. Perfect joiners are made with high pressure. So I dont think we should put Perfect into that discussion.
Also joiners on Xplorer will not break on these cases I think. They are "solid" joiners and seem very strong yet fairly light (atleast mine).
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Old Jun 09, 2009, 11:47 AM
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Jyvaskyla, Finland
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Quote:
Originally Posted by jojoen
If you can can find ANY Perfect joiner that have broken on landing I will be VERY surprised. I have not heard of any. Perfect joiners are made with high pressure. So I dont think we should put Perfect into that discussion.
Ok. Perfect joiners are just the same design as Aspire joiners... I have allways thought that the hollow design is intentionally made stiff up/down and break away fore/aft... The wall inside the joiner... Think about it - I am sure that (at least in theory) this is valid to any joiner with the same design.

During the past years I have broken couple of hollow joiners in accidents and once in accident-like landing. They are definately different from old type solid joiners... When hollow joiners brake, they do not just greate a small crack, they really break loose. I think this a very good thing

If you do not believe, I have to photograph the broken joiner that I left in clove compartment of my car Wing was left intact
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Old Jun 09, 2009, 12:25 PM
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Any Flying Field Across America
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Is there a way to inspect & repair now before a full failure might occur?

About two months ago my Xp got dropped on it's nose from a height of about 3meters with no other velocity components (just the downward drop). Since then I have not backed off of launching it with a full-pedal. I'm not the best of pilots and probably don't stress it as hard as others, but it still rockets after the zoom. So mine seems to be holding together fine (where's there a lumber yard that I can knock on all the wood I can find). But more importantly what should I inspect for before each launch to prevent a failure?

Thanks, Todd
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Old Jun 09, 2009, 12:31 PM
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OK I got confirmation on a broken Perfect joiner in a lock out/crash at landing. So it can happen. But they are not designed to break.

The Pike Plus and first Superior joiners were designed to break in hard landings. This was common in old times to save the wings. But then came the need for stiffer joiners and/or UMS rowing in them.
The first Perfect joiners were also "solid" and around 30g piece. But when the special moulds were finished (an cool and strange looking mould...) there is only the hollow ones supplied. Though the joiners from Philip Kolb is made "the old way" were the walls is made by wrapping depron that is placed in the moulds. Mould is then a fairly standard 2 piece steel that is screwed tightly together. They are not as light as the joiners from Samba (18g).

Joiners size on my Xplorer 3800 and Pike Perfect is almost the same. I could infact switch if I needed.
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Old Jun 09, 2009, 12:37 PM
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Quote:
Originally Posted by atjurhs
Is there a way to inspect & repair now before a full failure might occur?

About two months ago my Xp got dropped on it's nose from a height of about 3meters with no other velocity components (just the downward drop). Since then I have not backed off of launching it with a full-pedal. I'm not the best of pilots and probably don't stress it as hard as others, but it still rockets after the zoom. So mine seems to be holding together fine (where's there a lumber yard that I can knock on all the wood I can find). But more importantly what should I inspect for before each launch to prevent a failure?

Thanks, Todd
Might be that you will not see anything in advance. But if there is cracks around the joiner box hole I would stop flying and examine thoroughly by opening front and back of joiner box at tip/midsection ends (easy to enlargen the hole for servo wire and use a light to check glue around joiner box).

IF you can see there is space between joiner box and skin it means there is not enough epoxy. It should then be filled with 24h epoxy.
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Old Jun 09, 2009, 01:00 PM
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On a different note I got “educated” last weekend at a contest because I had not really setup my X for the kind of penetration I needed. I also made some hair brained decisions which I wont detail My plane survived though.

Wind was moderate to high at times and strong sink cycles were more than I bargained for.

JoJo noted his 3.8M did not have the legs he thought it should but was still tweaking. I read somewhere in this post that the wing has some camber molded in.

I changed my "clean" wing position and added 1mm of reflex across the surface and tested the performance and also changed my max reflex and elevator settings.

In some late afternoon test flights the plane really did not appear to be suffering any glide ratio loss and of course it was notably faster.

I have a CG of 106 now. If anyone else is using reflex in the normal cruise mode could you post your elevator position and CG? I would like to compare setups.
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Old Jun 09, 2009, 02:17 PM
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I have used 1-3mm reflex or negative camber meassured at flap and equal at all trailing edge. Have it on a slider togheter. Have not meassured elevator in the different positions. Though I am at 112mm CG.
The Xplorer 3800 does not have the legs I would have liked for above 5m/s conditions even with full ballast. It is probably better than my Perfect ET in calm conditions (yet to testfly in dead conditions with logging) but in windy conditions when you need to search or move I still prefer my Perfect ET.
Sebastian Feigl used his Experience Pro in the weekends conditions at Eurotour in Podhorany Czech. The conditions were extreme with sink and turbulence that I hav enot seen in any Eurotour before. But it was also a good test of model and especially setup.

Next competition I will probably choose Xplorer for calm conditions and Perfect for other. What I will choose in the future time will tell.

Regards Jojo
www.jojoen.no
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Old Jun 10, 2009, 03:34 PM
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Quote:
Originally Posted by jojoen
I have used 1-3mm reflex or negative camber meassured at flap and equal at all trailing edge. Have it on a slider togheter. Have not meassured elevator in the different positions. Though I am at 112mm CG.
The Xplorer 3800 does not have the legs I would have liked for above 5m/s conditions even with full ballast. It is probably better than my Perfect ET in calm conditions (yet to testfly in dead conditions with logging) but in windy conditions when you need to search or move I still prefer my Perfect ET.
Sebastian Feigl used his Experience Pro in the weekends conditions at Eurotour in Podhorany Czech. The conditions were extreme with sink and turbulence that I hav enot seen in any Eurotour before. But it was also a good test of model and especially setup.

Next competition I will probably choose Xplorer for calm conditions and Perfect for other. What I will choose in the future time will tell.

Regards Jojo
www.jojoen.no
JoJo - thank yo for your input.
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Old Jun 13, 2009, 11:12 AM
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Joined Mar 2007
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Jerilderie Handlaunch 2009 Results , report and images

Hi Guys,

Jerilderie Handlaunch 2009 Results , report and images can be viewed on the f3k.com.au website


Glad to be flying Perfects


I have some not so nice images of a xplorer failure.....mmmmmmm
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Old Jun 13, 2009, 12:22 PM
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London UK
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Quote:
Originally Posted by bellaflight
Hi Guys,

Jerilderie Handlaunch 2009 Results , report and images can be viewed on the f3k.com.au website


Glad to be flying Perfects


I have some not so nice images of a xplorer failure.....mmmmmmm
Perfects have failed on the winch too, so no need to be that way. I think its already been discussed about the reasons it can happen.

Many of us are glad we are flying the Xplorer too
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Old Jun 13, 2009, 02:27 PM
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X and reflex

Took my X out yesterday to tune my reflex settings a little more. The wind was moderate to strong at times but there was too much lift to really see how well the settings will perform when they are really needed (way down wind in sink)

My issues of recent have so much more to do with my general lack of attention to reflex mode when I encounter bad air. Once that wing gets into reflex mode the plane "scoots" along fairly well.

There is so much that the X does so well that I have no issues with the difference in legs that it appears to have compared to other planes. I would never expect the accuracy I have wiht the X out of my Perfects nor could I expect it to float like it does in light lift.

JoJo - you indicated the 3.8X had better legs than the Perfect ET (in early tests) do you think there is a reduction between the 3.5 and 3.8 X? in other words does the increase in squares noticibly increase the issue in high wind and sinky conditions?
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Old Jun 13, 2009, 03:35 PM
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Quote:
Originally Posted by webbsolution
.....snipp.....
JoJo - you indicated the 3.8X had better legs than the Perfect ET (in early tests) do you think there is a reduction between the 3.5 and 3.8 X? in other words does the increase in squares noticibly increase the issue in high wind and sinky conditions?
You mean Perfect compared to ET?
Have never flown the 3.5
The Perfect normal compared to the ET is that the ET is slightly slower but still enough to keep up a good pace. Actually the ET is more directional stable and likes the ballast.
I heard also several other Germans thought the Xplorer 3800 was a bit too big for windy flying. Yet I am still convinced with a bit of more tuning I would figure out some settings much better than what I have now. I need more flying on it. And as you mention one needs to do those tests in different sinking conditions.
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Old Jun 14, 2009, 01:45 AM
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Quote:
Originally Posted by jojoen
You mean Perfect compared to ET?
Have never flown the 3.5
The Perfect normal compared to the ET is that the ET is slightly slower but still enough to keep up a good pace. Actually the ET is more directional stable and likes the ballast.
I heard also several other Germans thought the Xplorer 3800 was a bit too big for windy flying. Yet I am still convinced with a bit of more tuning I would figure out some settings much better than what I have now. I need more flying on it. And as you mention one needs to do those tests in different sinking conditions.
Thank you for the clarification.

the Winds at the WC were pretty harsh and the german team still flew the X. This makes me wonder what they consider too much wind...

I too think you could improve the legs with good tuning. I have made some changes to my 3.5 and I am getting a good return on them so far. I will fly a bunch tomorrow and see how it does.
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