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When you think you're to experienced to make a simple mistake, you're not!

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David Davis26/08/2019 11:06:19
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3463 forum posts
621 photos

I took three models to the field yesterday including my Senior Telemaster (STM) which you may see in my avatar. I had not flown this model for several months. It's a high wing trainer made out of balsa and ply, covered in Solartex and powered by a Thunder Tiger 91 FS . I like it even thought takes a fair time to rig. It's twelve years old now and it could really benefit from a re-cover. The fuselage is a bit flexible and could do with strengthening but in flight the tailplane doesn't seem to wobble, besides I only fly gentle circuits and eights with this model. Sometimes I like to fly eights using the rudder to turn the model and the throttle to maintain a consistent height. It's that stable!

I was the first to arrive. Temperatures in the 30s ( about 85F) no wind to speak of except for thermals moving through. Wings out of bags and joined together, flap and aileron cables joined, wing bolts inserted and struts bolted to the fuselage fittings. Fill the fuel tank and the mighty engine burst into life after two or three turns of the starter motor. Check controls, all good . Carry the weighty beast to the runway, final check on controls, still good, push the throttle lever forward and the lumbering giant roars down the runway and into the air, smoke issuing from the exhaust. "That's impressive!" I thought.

I make a 180 degree climbing turn to the left to get away from the disc of the sun then level off. I still have the engine running at full power but realise that I'm holding in a little up elevator. "Funny, it's never done that before." I reach for the up trim and was rewarded with only two beeps of the trim before I ran out of movement. I'm still holding in a little up elevator then it began to dive, only a shallow dive but it was diving. Clearly something was wrong so I throttled back and brought it in to a safe landing. Nothing seemed to be amiss so I put the problem down to the flexible fuselage and I resolved there and then not to fly it again until I'd fixed it. I spent the rest of the afternoon flying my Baron and running in my Laser 80 on the test stand. "What's a Baron?"  Suffice it only to say that I am a competitor in a light hearted competion for these three-channel trainers on 7th September.

One of the younger members of our club is a man called Ludovic Jouinot. I suppose that he is about thirty years old. He repairs dented Volkswagens for a living and his models are always beautifully built and finished. He is very close to his sister Ludovine, and she often comes with him to the flying field. She is a charming young lady in the prime of life. After we'd finished flying she came up to me and asked whether I needed help to put everything away. I explained that it was quite a complicated process loading three models, the starting equipment, tools and a test bench into the van even though it is a two tonner, but she took an interest in the STM . I explained that the fuselage was wobbly and needed strengthening and that this had caused some dangerous flying characteristics before she had arrived so I had landed the model immediately. She stayed to watch me dismantle the model. First I disconnected the struts from the fuselage, then I unscrewed the wing bolts. It didn't require much effort.

I had fitted the wing bolts finger tight but I hadn't tightened them up with a screwdriver.

Consequently the trailing edge was lifting in flight causing the model to dive.

Now what does Bart Simson say?

Edited By David Davis on 26/08/2019 11:07:15

FlyinBrian26/08/2019 12:13:42
525 forum posts

DOH!

McG 696926/08/2019 12:26:24
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2706 forum posts
1015 photos

... are you sure that the charming Ludovine wasn't already next to you when you fitted that wing to your STM, David... ???

You can tell me, no probs... I'm good at keeping secrets. angel

Cheers

Chris

Jason-I26/08/2019 12:35:07
268 forum posts
37 photos

Bart Simpson - Eat my shorts, Ay Caramba

Homer Simpson - D'oh!

wink

Edited By Jason-I on 26/08/2019 12:35:58

Don Fry26/08/2019 12:56:22
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4116 forum posts
48 photos

I wondered that McG, note sentence one, paragraph two. Clearly an unnecessary statement. I leave it to you as a trusted confidant.

Charming in the prime of life indeed. You can almost see a moustache wax purchase coming along. Not by her I might add.

David Davis26/08/2019 13:48:15
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3463 forum posts
621 photos

Jason, it was Homer Simson I was thinking of but I haven't had a television since they went digital.

Chris and Don, Ludovine is young enough to be my grand daughter and I'm very happy with my English Rose.

trish and me at the ulster memorial on the somme 1st july 2019.jpg

I do need to order some more moustache wax though!

alex nicol26/08/2019 16:39:50
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305 forum posts
15 photos

I think that's called a senior moment ........... I've been prone to a couple of them myself lol

jeffrey cottrell26/08/2019 18:58:03
71 forum posts
6 photos

Hi David

Interesting story, Puts me in mind of something that happened to me a while back, and also begs a question.
So, I'm out flying my Limbo Dancer. Normally a well behaved model and fun to chuck around.
This flight seemed a little imprecise in the manouevers and had the annoying habit, after a loop, of adding another tight uncommanded loop.
Anyway, landed pretty quickly.
Mulling over what could be wrong when my mind was made up for me. I spotted that one of the wing bands had actually split and was lying under the model.
So, problem solved, but led me to wonder just how long wing bands are supposed to last.
I used white SLEC bands and never left the model assembled and the bands under tension.
Now replaced the bands with some brown ones, and using 6 instead of 4 and the model is back to its normal good flying.
However I am concerned that the bands might have let loose in flight with predictably unpleasant results, so how do I know when the bands need replacing?

Over to you experts

Jeff

leccyflyer26/08/2019 20:35:48
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1288 forum posts
302 photos

Four wing bands isn't really enough to hold the wing on firmly IMO - I always use six or eight bands. You should be able to pick the model up by the wing without any movement on the bands. They also have a finite life and need to be replaced regularly. In practice I think I probably replace them every 2-3 years, but they are used infrequently, since I greatly prefer bolted on wings.

Bob Cotsford26/08/2019 20:57:51
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8058 forum posts
444 photos

If they get fuel on thm then they need washing and drying. Store them in a dark bag or tin, when I used glider bungees we used to dust them with talc after use. I reckon UV kills them pretty quickly, and yes, I think cheap brown bands seem to last longer than the white ones.

J D 826/08/2019 21:06:34
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1317 forum posts
78 photos

Flying a Limbo Dancer with only two wing bands results in a clapping sound as the wing lifts and drops back in place. Lucky to land OK.

fly boy326/08/2019 21:10:21
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3535 forum posts
18 photos

Re elastic bands, do you folk use what I call normal bands around quarter of an inch wide, or so called wing bands from slec where are much wider. Cheers

jeffrey cottrell26/08/2019 21:26:17
71 forum posts
6 photos

Hi Guys, thanks

Leccyflyer
Started off with four bands and never had a problem until recently. Model can't be more than a year old.
Having found a source of cheap bands I have now gone to six and will stay that way.
Guess I needed to know how often they should be replaced, or if there were any early signs that they were reaching the end of their life.
Bought a big bag of bands off e-bay, so I could replace them every year as a precaution.
I don't leave the model assembled and the bands under tension, and it is stored in a shed so exposure to UV is only when it is out flying.
Don't think that's too much of a risk.

Bob
This one's electric, so no fuel contamination. Glad to hear the brown bands last longer.
Good news to my wallet.

JD8
Not sure where you got the idea I only used 2 bands. It's always been a minimum of 4, and now I'll use 6.

fly boy3
I have found a source of brown bands on e-bay, but these are 10mm wide, so much the same as SLEC ones.

Cheers

Jeff

J D 826/08/2019 22:59:54
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1317 forum posts
78 photos

Jeff , It was me using only two wing bands, just forgot to fit the others.embarrassed John.

David Davis27/08/2019 05:09:36
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3463 forum posts
621 photos

Jeffrey, I used to have a Limbo Dancer. It was great for doing low inverted passes until one day I joined the "Up Elevator Club!" There's not much to a Limbo Dancer is there? blush

As for using only four elastic bands, I was in the process of selling surplus stuff prior to retiring to France. Among the surplus stuff was a Telemaster 40. There was a novice pilot at my local club and I'd planned to sell the T40 to him after a demonstration flight. The model was well flown but apparently in good condition. What could possibly go wrong? I secured the wing with four elastic bands, took off, gained altitude, and then the wings flew off! surprise

Too few elastic bands? Wing dowel giving way? I don't know but it went ftom this

Rapsody in Blue!

to this in a matter of seconds.

rip t40 (1).jpg

The wing, of course fluttered down to the ground undamaged. I still have it but somewhere along the way I lost the tail surfaces. One day, if I live long enough, I'll build a new fuselage for it!

leccyflyer27/08/2019 08:09:07
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1288 forum posts
302 photos
Posted by jeffrey cottrell on 26/08/2019 21:26:17:

Hi Guys, thanks

Leccyflyer
Started off with four bands and never had a problem until recently. Model can't be more than a year old.
Having found a source of cheap bands I have now gone to six and will stay that way.
Guess I needed to know how often they should be replaced, or if there were any early signs that they were reaching the end of their life.
Bought a big bag of bands off e-bay, so I could replace them every year as a precaution.
I don't leave the model assembled and the bands under tension, and it is stored in a shed so exposure to UV is only when it is out flying.
Don't think that's too much of a risk.


I have found a source of brown bands on e-bay, but these are 10mm wide, so much the same as SLEC ones.

Cheers

Jeff

Most of my models with wing bands are slope soarers. So their wing bands are stored in the rucksack that I use on the hill as a transmitter case, butty and flask carrier and transport for waterproofs. In terms of spotting when they are coming to the end of their life, they are given a good stretch before being fitted on the model - if they show signs of perishing they are delberately snapped and discarded.

Typically I only use the white soft rubber bands on the soarers, and they last a long time, like you said they are only being exposed to UV whilst I'm out flying but some parkflyers do have standard brown bands. I haven't noticed any difference in longevity if the bands are stored out of the sun. I use ordinary thin office bands to keep the wings on a couple of parkflyer models which are hung up for storage. Those thin bands, in tension, don;t last more than a year max.

David Davis12/11/2019 17:47:40
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3463 forum posts
621 photos
Posted by Don Fry on 26/08/2019 12:56:22:

... Charming in the prime of life indeed. You can almost see a moustache wax purchase coming along. Not by her I might add."

Many a true word spoken in jest!

moustache wax (1).jpg

Don Fry12/11/2019 19:39:26
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4116 forum posts
48 photos

Silence is a virtue.

McG 696912/11/2019 20:06:04
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2706 forum posts
1015 photos

+1 on the virtue of silence, Don.

... but then what are the 'Bounder' thingies?

... some kind of marmelade?

Cheers

Chris

David Davis13/11/2019 04:49:26
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3463 forum posts
621 photos

Moustache wax is used to prevent the ends of one's moustache from drooping, as in this picture of your humble servant presenting a wreath from the local British community at the village war memorial two days ago.

I wish I could think of a use for the little empty tins. wink

armistice day 2019.jpg

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