Wing Failure???

[Kelly]

Hi all

 

Update on the replacement Boomerang 40.

 

Picture of the wing ally tube,also the centre section sheeting has been extended .

 

Seagull  have listened

 

Kelvin

[Stephen Grigg]

My Boomerang lasted until it dropped Kelvin

[Phil 9]

I flew my new Boomerang yesterday. I will be holding off doing any loops with it for now.

 

I did get some damage on it on my third flight. The engine cut out on take off and it dropped from the air heavily.

 

damaged report as follows

 

front leg bent and wheel came off (lost the collets)

scuffed the nose

one wheel broken

wing tips damaged.

 

I found a spare wheel and use some CA on the wing tips. It is good to go again.

 

Edited By Phil B on 15/01/2010 10:00:36

[Bruce Richards]

Phil, I had similar happen to my Boomer when I first started. Have you checked the formers in the nose that hold the tank in place. After my incident thay were all broken but it was only visible when the tank was removed.

 

[Phil 9]

I did not check but i will now thanks Bruce. I would not even have thought to look there.

[Former Member]

[This posting has been removed]

[Lee Damms]

Hi Kelvin I've had my Boomerang 18 months now and its had a hard life mines got a plywood wing joiner but after putting into a grassy bank at full throttle the fuselage was in bits but the wing survived intact.  The fuselage was rebuilt and she still flies today, this has got to be one of the better ARTF's, but I'm glad that Seagull have seen fit update it.

[Kelly]

Hi Eric, 

 

Used 2 bands cossed and 2 bands fore and aft.

Lack of glue on the box spar was the cause.

Hi Lee,

 

Just got a duff one,must be a few of them about for seagull to improve  the wing joiner 

[Martin Harris - Moderator]

I'm not suggesting this caused your problem as it seems Perkins have accepted the lack of glue in this case but on the subject of bands, it's very important to ensure that the leading edge is held down effectively by sufficient bands of an appropriate length. If it can lift you can get into a runaway situation where you pull some elevator, the LE lifts, tightens the zoom, lifts the LE some more, tightens etc. etc. until the wing stalls - or breaks if it isn't strong enough.

[Peter Beeney]

If I might add another fairly predicable comment to this Boomerang aluminium tube wing joiner chronicle, we have a Boom as the club trainer, with the ally joiner, and this model seems to be very robust. It’s dragged around by an Irvine 53, turning a 12 by 6 APC, which makes it all a bit lively, and is very frequently flown to the limit of G, and maybe even beyond, but I have total faith in the integrity of the airframe and wings. In fact, I’ve had very few problems with the wings on any trainer, it’s the tail-planes that invariably seem to give up the ghost first, by generally becoming loose and weak and wobbly; I suspect due to all the constant spinning, flick-rolling and all the other all-sticks-in-all-the-corners stuff that we inflict on them; and, of course, I always use maximum control throws. I realise this is probable not quite how they are supposed to be treated, but generally speaking they put up with it remarkably well.

The wing bands may also be a little pointer, too. I would certainly agree with Martin here. Over the years I’ve seen a few models that have had insufficient bands holding the wings down, and what usually seems to happen is this. When pulling a touch of up elevator at the end of a power dive say, the sudden increased angle of attack, and resultant lifting affect, causes the wing to lift sharply away from the fuz and stretches out the rubber bands. There is now nothing to keep the fuz continuing on it’s previous course so due to the extra elasticity in the stretched bands it very quickly tries to play catchup and snaps back up against the wing. The upshot of this happening is that the model can give a very violent lurch upwards, sometimes accompanied by a very audible crack as the fuz rejoins the wing.
If anything like this starts going on you need more wing elastic!

I use 10 bands, the white JP 8” variety, I’ve not managed to lift the wing on the Boomer with this degree of tension, and although I spend time caring for the bands they can still become a bit perished and saggy so I renew them as and when required.
I had an original Wot 4, this had wing bolts and a dowel at the front and this started giving little upward flips, which, after some poggering over, proved to be an itsy-bitsy amount of wear on the dowel. Just an almost imperceptible amount of play was enough to allow the wing to lift.

Years ago, one of reasons considered for using rubber bands to hold the wings on was that in the event of a crash the wings could swivel or perhaps become detached, thus lessening the damage. I think we soon began to realise that when there were enough bands on to hold the wing securely enough to fly properly this advantage was lost! It would be rigid anyway!

We consider the Boomerang to be a good all round suitable trainer, for one thing it has a useful wing section, but we would always modify the nose wheel to a permanently straight-ahead fixed position; and even then it will give you grief if it can. I’m not entirely sure that beginners are that interested in steering around on the ground anyway.

PB