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Old Dec 13, 2014, 02:12 PM
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United Kingdom, England, Wigan
Joined Jul 2011
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Originally Posted by zatopec View Post
Thank you all, for your very kind comments on my work. I would like to pay tribute to my very good friends David and Mike, without their continued help over the last few months I would never have achieved what I have achieved. Thanks to you both.

Christine
Christine

You built it.... And very well you did it too.. It's dead straight and true!

Mike and I were there in a purely advisory capacity on what was a quite complicated (wing) build... Well done girl!


Trevor

Yes it was running on just the one BEC.. And that was the wrong one of the two!

David
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Old Dec 13, 2014, 02:57 PM
71% of the world is runway . .
Bart83's Avatar
Nederland, ZH, Oostvoorne
Joined Jun 2009
1,970 Posts
Congrats !! beautifull maiden and indeed a perfect timing for the bec failure. Lots off discusion on using bec's on multi engined planes. I choose a seperate Ubec for reciever power and use te bec from the esc for the nav and landing lights.

Cheers,

Bart
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Old Dec 13, 2014, 06:23 PM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
3,791 Posts
Nice job, lovely photos, Hooray!

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Old Dec 14, 2014, 03:53 AM
...design-build-fly-publish...
eye4wings's Avatar
Ware, herts. U.K.
Joined Sep 2008
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Congratulations to builder and flyer on an excellent first flight.

It seems appropriate to me to reiterate my view on the risk we take by disabling all but one of our available radio power sources in following 'conventional wisdom'.
This seems to be based on the assumption that the tollerances in electronic components would result in two (or more) slightly different voltages being offered to the system, but we then put all our eggs in one basket. My understanding is that the higher of the two voltage sources will supply most of the current drawn by the system so provided we make sure that one BEC can supply all the demands on its own we are not wasting the opportunity of having the second BEC take over automatically should the first fail.

The only risk we take in doing this is that the first unit may fail without our noticing putting us back in the situation we would have been in anyway by disabling one.

One alternative among many is to build (at the expenditure of about 1 and an hour of time) a piggy-back board that mounts directly onto the receiver and divides the work required of the BECs without them being linked directly. This can be arranged so that as far as possible half of the model is supplied by each BEC and both supply about the same current. The receiver can only have supply from one side of course with this arrangement, so there is no safety advantage, but should the other fail then the Rx and half the model is still capable of being operated so as to land safely.

With this kind of thinking it is possible to use multipe BECs to supply different functions so that our models are inherently safer.
For those of us building larger models we are already installing our bespoke extension wiring throughout the model anyway so a little more thought allows us to achieve better safety, but although I am using a 12A uBEC for the Stirling's radio and system for example the onboard BECs can be used for other things like lighting for example. There are so many options available to us - and I have never had any problem direct linking two BECs on the occasions I have done that.

Robin
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Old Dec 14, 2014, 04:39 PM
What could possibly go wrong?
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Market Harborough
Joined Apr 2006
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Quote:
The only risk we take in doing this is that the first unit may fail without our noticing putting us back in the situation we would have been in anyway by disabling one.
Sorry Robin, I can't agree with that. You've missed out the risk of the 2 BECs interfering with each other. Sure, the Rx takes the highest voltage no matter which BEC is producing it. But the BEC with a lower voltage is also taking current from that source, and all changing at very high frequencies.

Keep It Simple works for me.

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Old Dec 14, 2014, 06:05 PM
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Canada, BC, Comox
Joined Nov 2003
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Quote:
Originally Posted by nickchud View Post
You've missed out the risk of the 2 BECs interfering with each other.
Castle Creations actually recommended that I keep both BEC's active when using their Phoenix 25's in my Twin Otter. So I did, and have never had a problem, and the airplane has been flying for over 10 years now.
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Old Dec 15, 2014, 02:29 AM
...design-build-fly-publish...
eye4wings's Avatar
Ware, herts. U.K.
Joined Sep 2008
3,518 Posts
No need to apologise Nick - anyone is allowed to disagree - and there may be manufacturers who still recommend disabling their units so only one works.

I started out using ESCs with linear BECs back in the year mumble-mumble and was told they could be used together so, like Frank, I did and have happily gone on doing so with other manufacturers' products as well, without apparent problems.
Unlike Frank I have never considered Castle Creations equipment to be in my price range (which is normally the cheapest available subject to peer reviews) but I am glad to see they have thought about and presumably designed for those who, like me, hate to see capability going to waste.

My point is that Christine's model could so easily have been lost with the failure of the single BEC in use and that the risk of disaster could so easily be considerably diminished with a change in thinking.

Robin
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Old Dec 15, 2014, 05:22 AM
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United Kingdom, England, Wigan
Joined Jul 2011
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Robin
Your last paragraph really sums up the situation
This test flight day could have ended in total disaster!
A chain is only as strong as it's weakest link...
The model airplane gods were indeed kind on the day!

David
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Old Dec 15, 2014, 08:57 AM
Slip the surly bonds...
Sopwith Mike's Avatar
Christchurch,England
Joined Aug 2004
2,730 Posts
Congratulations Christine - I missed this because I was on a pre-Christmas holiday but what a beautifully built and finished model. The Sealand is one of Ivan's best.

Perhaps I can enroll you in the growing BIMBO membership... There is no fee!
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Old Dec 15, 2014, 09:33 AM
GLM
AMA 209854
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Check Six!
Joined Oct 2003
1,520 Posts
A couple of Spirit of Ivan Empires at a recent float fly.

All these flyers favorite thing to do is land on the water - once hooked - well you know...

At the end is what we think was a failure of the port ESC on take off.

Cheers!

Gary

Trip Video Frank Karl Gary Nick (9 min 17 sec)
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