Elapor, Cyano and a good day ruined

[Brian Parker]

Yesterday I felt the need for some relaxed soaring, so took the EasyGlider out for an airing.
Conditions, despite the forecast, were perfect with plenty of lift almost to the edge of eyesight (my).

 After some enjoyable soaring and several manoeuvres later the limits of the EasyGlider were revealed.

 Or was it the limitations of Cyano?

 She failed to pull up out of a steep dive, the left tailplane detached, hung on to the elevator for a moment, freed itself and fluttered down on its own.

 The EasyGlider was previously in perfect condition with no added ballast.

 

Later inspection at home revealed that the right-hand side of the tailplane was almost detached, cracked exactly at the same point as the left hand side. (Hard to see in photo).
Obviously a localised stress point.

 

The impact was heavy at about 20 degrees from the vertical but was into longish grass/moss and peaty soil, although, all equipment, including the servos (spot cyanoed in) were ejected.
She looks surprisingly clean but is a bit green under her nose.

 

It is now repaired and looks like new (well almost).
Was this a direct result of the lack of elasticity of the cyano glued joint?

 Would she still be in pristine condition if flexible glue had been used?

Or was she pushed to hard?

 

ps. Sorry about the oily building board, 'tis the engineering board, not the construction board.

[PatMc]

But it's not broken at a glued joint so why suspect the cyano ?

[Brian Parker]

Because the cyano, being rigid, is not allowing the Elapor to flex at a localised stress point.
 It may well be that the model was driven too hard and the cyano was not to blame. Object of posting was to invite comment or to see if anyone else had suffered the same.

[Peewhit]

Bad luck with the EG Brian!

 

CA and "kicker" will repair almost any elapor break - could even use some carbon rod to reinforce.

 

What sort of manoeuvres were you doing?

 

The EG is a gentle beast and whilst it will perform a decent loop, it is not really designed for aerobatics or steep dives.

 

Something has stressed out the tailplane - could be too big an elevator throw, or could be too harsh treatment!

 

Keep the EG for gentle flying in gentle conditions, and go get an SAS Fusion (or similar)for bigger lift and aerobatics.

Edited By Peewhit on 15/07/2009 20:25:05

Edited By Peewhit on 15/07/2009 20:25:27

[Andy Freeman]

Closest I can say is a month or so ago i had the EG completely specced out at the Blyth field. Thinking it was on its way to Denmark i pushed it into a dive. After about 20 seconds the airlerons stopped responding. Fortunatly the elevator and rudder were still functional. Even though there was an unnatural bend in the wings i blame the chaepa and nasty servos i had installed. Rudder and elevator are HS82mg and in the wings are 9g cheap and nastlies from a local Eflight specialist. 

 

Moral of the story for me is the fact that the Eg is a stooge about the place model and not designed to be beasted!

 

There again what would i know....just the observations of an idiot

[Peewhit]

Observations of another idiot seem to be similar Andy

[Brian Parker]

Peewhit,
Have a Fusion.

 The dives were quite a long and steep (almost vertical) .

I have reinforced the tailplane and elevator with carbon strip and used carbon pegs on the join.

I had expected a light breeze, but it was fun while it lasted.

Andy,

Perhaps I need to act my age

[Chris van Schoor]

That beak is not normal.  The EG can handle a reasonable amount of abuse in the air (particularly the tailplane).  Admittedly it's not a hotliner or racing glider, but It shouldn't be necessary to fly it with kid gloves in the fear that it may break: that would go against the whole point of owning one.  The only possible cause that comes to mind is prior damage caused by transport or storage. Particularly in the car, the tail is difficult to protect..

[Brian Parker]

 Chris,
Definitely no prior damage either due to storage or transportation.

[Peewhit]

Brian,

These Fusions are really good fun, especially when ballasted with a few ounces of church roof.

Glad you have fixed the EG.

I think we have all been caught out by unpredictable weather.

 

It seems strange that both sides of the tail broke in virtually the same way - could just have been the stress from your long steep dives - a weak point or model just not designed to cope?

 

I have had the complete tail come off my EG - didn't use kicker - hence am now on my second one!

Have also put it into some steep dives prior to loops, but no sign of any breaks in the tail surface.

 

So what wind speed were you flying an unballasted EG in?

[Former Member]

[This posting has been removed]

[Brian Parker]

Peewhit,
 I forgot the anemometer but the wind speed was probably in excess of 12 mph gusting to 18mph perhaps higher.

Tried it out today, wind speed 10mph (measured) with the odd higher gust, plenty of lift (more than Tuesday).

 Gave it a good wringing out and she certainly seemed more responsive. Perhaps with the carbon reinforcing in the tail she was more able to hold she own.

 Also had my Weasel out on both occasions, highly recommended and excellent value for money.  I have it fully taped and she is a little overweight (she initially ended up tail heavy) but is superb. I intend to send for another and keep uncovered for lighter/lazy days.

 My fusion also carries a lump of lead in her belly and she is all the better for it.

 

Eric,

Thanks for input. I only had the tail fail in mine; control is via snakes and MG servos.

Andy had the ailerons freeze.

[PatMc]

IMO flutter is the most likely cause of both. The tailplane failing/cracking at the same point either side seems to back this up.

 

Andy's incident could have been caused by the ailerons fluttering violently enough to damage the servo gears. ie the surfaces moved but the ailerons tried to hold.

 

Andy, next time you want to lose height fast try spinning the model down. It's much safer & doesn't stress anything - so long as it recovers to normal flight in time.

What type of servos are you using now in the ailerons ? I'm using Zebra ZS-F135MGs. 

[Brian Parker]

 

On reflection and with due respect to all, I don't think it was flutter.
The dive was as straight as an arrow with no oscillations of fuselage. There was absolutely no slop in any linkage.

 The break was at the exact instant of my input and she failed to pull out. To me this is catastrophic structural failure.

The break was clean with no sign of repeated compression, tension or torsion.

 I am still of the opinion that the lack of flexibility due to the cyano was a contributory factor. If you look at the photo, the crack starts at the rear of the tail where it meets, and is glued to, the rear of the fin (localised stress point) it moves forward and outwards equally on both sides of the tail to meet the leading edge. Bearing in mind the resultant forces, I would have expected the crack to be more parallel to the fuselage. 

Anyway, as I posted earlier, although not as pristine, she still performs well with her new carbon splints and she cannot expect to be confined to easy glides in the future.

[Chris van Schoor]

I dunno Brian.  I really, really dunno about that theory..  I guess this is just one of those times where we will all have to agree to disagree..

[Stubee]

Intresting to see that other people have had 'problems' in hi speed descents. I was doing a beat up with my EG descending steeply when pulling back on the stick had little effect, it gradually eased out as the hedge on the far side of the field (and ground) got closer! I wondered if it was the servo's not man enough (Nano s) or perhaps an aerodynamic issue. After seeing what happened to Brians model I may be more careful and inspect that tail area.

[Alex Leigh]

Well I've been chucking mine around today in about 15mph of wind. About the limit I'd want to fly it on my slope, but as the wind dropped a bit, I tried giving it a bit of stick and had no problems at all. Although I'm not doing very long vertical dives.

It's an amazing glider really, prefer flying it to my Blizzard. I do check it before flying now though after reading this thread to see if anything looks loose!