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My Bixler 1.1 has a non-successful maiden.


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It was very well packaged. More likely it happened, (perhaps?) when I very carefully glued the two halves of the fusi together. I used Uhu Por which gave much more assembly time than hot glue,  but I started from the nose when putting the halves together.  It's logical, start at the big end I thought. Foam is flexible and stretchable. It's 35 inches long and when I got to the tail the end it was slightly out. Only a couple of mm but it did annoy me TBH but there's no way you'd pull it apart again without wrecking it to correct it. You get one hit to get it right. Maybe that distorted it?  Who knows.  If there was a next time completing the ARTF  I'd probably start in the middle putting the halves together. 

 

And I will post my flight attempts today, there were a lot before I got it flying ok, and my conclusions video tomorrow if I get a chance to edit it. I'll keep you in suspense! But it was not a CoG problem! 

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Any foam model especially those with long thin fuselage like the bixler are flexible. They often bend when flying at speed and can ho out of control. I test flew a model for a club mate of similar size and configuration to a bixler made for EDF power unit . It had an upgraded EDF fitted so was considerably more powerful than intended. Flight started fine but as speed built up it became uncontrollable.  As rhe speed drop control was regained and the model was landed. On inspection all seemed OK but the fuselage between the wings and tail plane was found to flex enough to cause the problem. Four lengths of carbon fibre strip 1mm x 3mm were inserted , one at the top and  bottom and one either side. Simply make a slit with a scalpel and push the strip insnd run thin cyano along it. Problem sorted . The airframe can now   handle the stresses put on it in flight.

This was also a problem for the mk1 HobbyKing Venom that had flexible booms . The  addition of carbon strip transforms the airframe. 

Worth checking out and wont cost a lot to fix.

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1 hour ago, Engine Doctor said:

Any foam model especially those with long thin fuselage like the bixler are flexible. They often bend when flying at speed and can ho out of control. I test flew a model for a club mate of similar size and configuration to a bixler made for EDF power unit . It had an upgraded EDF fitted so was considerably more powerful than intended. Flight started fine but as speed built up it became uncontrollable.  As rhe speed drop control was regained and the model was landed. On inspection all seemed OK but the fuselage between the wings and tail plane was found to flex enough to cause the problem. Four lengths of carbon fibre strip 1mm x 3mm were inserted , one at the top and  bottom and one either side. Simply make a slit with a scalpel and push the strip insnd run thin cyano along it. Problem sorted . The airframe can now   handle the stresses put on it in flight.

This was also a problem for the mk1 HobbyKing Venom that had flexible booms . The  addition of carbon strip transforms the airframe. 

Worth checking out and wont cost a lot to fix.

 

Yes, thanks.   I had Googled the model before buying and I knew some Bixler builders had done that.   I considered it and  I've done it on some of my Lidl glider conversions, but I didn't really want to add that much extra weight to the tail.  I'll re-consider it now!

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I have witnessed a weird issue on one of those Easy Star / bixler type models , It was one of those Multiplex  small versions of the Easy Star , forget the name , but teaching someone to fly on it was a night mare !  

If left in the sun , the fuz went like a banana and was easy to see the bend , left in the shade it went straight .The main problem was flying when bent , it gradually straightened in the air requiring constant trim changes , It needed a mixer input of outside temp/ rudder.

cheers     

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Well I got it flying in the end after a long afternoon of trimming and experimenting and in the end it became obvious that it wasn't a CoG issue as had been suggested, and  I didn't need the 60 gms of lead on the nose.  My cut and shut to change tail incidence pretty much solved the problem. But also,  having used a different motor and prop to that in the RTF I concluded it was overpowered and  the bad incidence was what caused it to climb so hard even when on reduced power or trying to glide in to land.  Now with the incidence changed a bit it's quite happy at half throttle, and I've changed the prop from the 5045  3 blade  to a 6 x 4 which is the size Bixler use, it might help to depower it a bit. 
Other observations. It's very easy to build twists and bends into the fusi if the you are putting together the ARTF version. But my cut and shut worked ok.  I have found that instead of putting carbon into the tail to stiffen it, tape is just as effective.  
  
All in all a good learning experience.  And I know I need to improve my throw.

 

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  • 1 month later...

My Bixler 1.1 died recently after a catastrophic ESC failure.  It was my 'goto' aircraft for throwing around & gliding, and was quite battered after over 2 years of regular flying.  It had plenty of power for climbing yet could glide for 30 minute flights and land with plenty of battery remaining.

 

Looking at your video it was very tail heavy.  I found that a 2200 was too light and always flew with a 3000 right forward in the nose.  It balanced perfectly and flew on rails.

 

Why the 3-blade prop?  The stock 6x4 two-blade delivers plenty of power.  If it ain't broke don't fix it!

 

My only crit of the Bixler is that it has no ventillation so the ESC can cook on a hot day.  I 3D printed a scoop for the nose and vents under each wing which helped to cool the ESC.

 

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Hi Phillip,  

 

Sorry to hear that!  

 

On Wednesday I finally managed to get mine flying really well.  I had changed to angle of incidence on the tail after that flight, as I think I built in a bend when glueing the two fusi halves together, but it was still porpoising at times. I'd also tried more nose weight. 

 

The last thing I tried was a little down trim on both ailerons. Bit of an experiment really to try and change AoI a bit more. Anyhow, Wednesday it flew really well , best at half throttle. It is a bit overpowered with the motor prop I had on. I changed to a smaller prop too.  It was floating around and dead easy to fly. Full chat it looped easily .

 

Re the ESC overheat, I have seen people mount the esc on the outside of the fusi in the airflow. Or as you say, fit a scoop. White plastic teaspoons cut off make a good scoop!

 

 

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  • 4 weeks later...
13 hours ago, James Humphreys 1 said:

My bixler flew fine straight out the box no nose weight etc for months, Here's the rub though while doing a club funfly she started to porpoise and turn where before she'd glide hands off, when checked over by several people and flown by them aswell weight had to be added to the wing and to the nose. WEIRD 

Mmmm, that is weird, maybe the fusi developed a bend. Distorted in sunshine or something?  Mine didn't come ready to fly , I even had to glue the two fusi halves together and it was too easy to build in a bend while doing so. The incidence of the tail was out which I think contributed to my problems. Got it sorted in the end though and it flies well.

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