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January 2012 issue


Steve W-O
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Stephen
I agree -Nothing wrong with it .Only wished I'd done it whilst i was building but the bulkheads etc were cut out for a side winder if I remember correctly.I prefer an engine upright any time for loads of reasons as you well know .Are there maybe different kits from my own by Flair since their inception ? I bought mine about seven years ago .A lot younger than the one in the mag (15-20 years ),so I don't think that that is the answer actually.
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  • 3 weeks later...
Jan 2012-Tanks- Brian Winch........As an all electric flier, I should not be doing this, but I can't agree that that bendy clunk guy was asleep during Newton's lectures. Inertia means just that - a body, in this case fuel, wants to keep doing what it was doing before any acceleration. The fuel, when a plane is flying straight and level, will not be "pushed along by the back of the tank" It will settle on the bottom, just as in real planes, cars etc. When you accelerate the fuel will slosh to the back, and if you decelerate it will slosh to the front. Try it in a car with a half full bottle of water held horizontally and all will be clear. In a dive, providing you are not accelerating faster than freefall, the fuel must fall to the front of the tank. Some full size gliders have speed limiting brakes and will hold 90kts. or so in a near vertical sustained dive, and the pilot does "hang forward" in his straps. I am taking a big risk here, not having any clunky tanks, but I am sure your clunks must be out of fuel a lot of the time when doing aeros, and I can't explain why your motor does not cut when you shut the throttle suddenly or during a sustained dive - perhaps because with models everything happens quickly. Maybe there is enough in the tubes? I am sure someone is going to tell me!
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Posted by Erfolg on 22/01/2012 16:41:02:
Isn't the clunk affected by inertia in the same way as the fuel?
 
I would expect some divergence in the way they respond, due to a number of effects, but in essence the forces the fuel sees, so does the clunk?
 
 
 
Agree. In a vertical dive, when the fuel gravitates to the front of the tank, so does the clunk pickup. And when inverted the clunk 'falls' to the tank roof where the fuel is. Surely that's the whole point of 'em?
 
Regards
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I am glad we seem to agree.
 
The only complicating issues (I can immediately think off) are the fuel tube that the clunk is attached to, which can be considered to be a spring (rather weak and flexible) and friction of the clunk on the tank wall on a random basis. Oh, and the fluidity of the fuel, not necessarily behaving as a single entity.
 
Whatever the situation, clunks seem to work. Perhaps the one exception would be near vertical dive, of any length, if the clunk tube is stiff.
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Myron, as you now I am now an electric flier.
 
The problems that I actually see, is that most of us engineers tend to pick an instant, to consider what is happening. The real situation is that many models are constantly changing direction, so rather than favourite equilibrium model so loved, the situation is pretty much chaotic. The model never staying any one position for the considered equilibrium model to be achieved.
 
The dive situation does fox me a little. I am pretty sure that most fuel clunks cannot bend forward up to the bulkhead in a vertical dive, due to the resistance of the clunk tube. But then again, does the dive last long enough for all the fuel to move fro the back to the front, particularly if the model is accelerating, as then the inertial forces would then tend to see it stay where it (both) is, at the back.
 
At the end of the day. clunk tanks work.
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Posted by Erfolg on 22/01/2012 17:35:58:

 
The dive situation does fox me a little. I am pretty sure that most fuel clunks cannot bend forward up to the bulkhead in a vertical dive, due to the resistance of the clunk tube. But then again, does the dive last long enough for all the fuel to move fro the back to the front, particularly if the model is accelerating, as then the inertial forces would then tend to see it stay where it (both) is, at the back.
 
At the end of the day. clunk tanks work.
Hi Erfolg
 
Well , mine certainly do! I can't actually prove they do it in flight, but they often do it when I stand the model on its nose to do some work on it - or take the wing off. And they sometimes don't straighten themselves out without a bit of a shake. On more than one occasion this has proved to be the reason for the engine cutting out when the model was held vertical to check it wasn't too lean. Had me foxed for a bit the first time as richening up the needle obviously had no effect.

Regards
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  • 2 weeks later...
Just finished reading this one, and now started Feb's edition, question for David really, how come a review of the TT glider you did in the Jan edition, you are wearing a t-shirt and the sun appears to be out, and therefore it's not quite a current review is it, assuming this was done back in the summer?
 
One other review in the same mag also appeared to be no where near the publish date, just wondering if you are playing catch up all the time due to maybe a space restriction?
 
 
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Hmm, yes and no really. It varies model to model and for all sorts of reasons.
 
For the ehawk - we put the Jan issue to bed during the first few days of December and material for it had to be ready around mid-Nov'ish. The eHawk was photographed during its first flights late Sept when we were working on the November issue but I wanted to get a few more flights under the belt so it missed the Nov & Dec deadlines.
 
 
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