Yorkman
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Posts posted by Yorkman
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JR/Spektrum, but middle is the important part!
pondering on the UBEC-the next one up-the Hobbywing 5-7.5A is 3x price (big deal-12 quid) but also 3x the weight...?
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thanks Timbo-will nip back to giantcod a minute and have another look....
can you please confirm red middle wire?
ta
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Timbo wrote (see)
So I reckon that even with a fully stalled servo, and the others all working hard, the current drawn from the battery should not exceed .75A and that is allowing a high margin. The output current of the UBEC @ 6v nominal should be around 1.5A, which is well within the rating of 2.5A continuous.
In normal flight conditions, with good non-binding control runs to flying surface controls, I expect the current output from the UBEC to average around .5 to .75 Amp.
I found the current draw of the digital servos surprisingly low against what I expected, and the experiment also proved the benefits of using a switch mode regulator with a good high voltage input, in so much as the current required to be supplied by the battery is much lower than it would be if using a normal flight pack 4 or 5 cell battery.
I feel this also further enhances the case for using a 2 or 3 cell LiPo with a suitable regulator to power onboard radio gear - not withstanding some peoples reservations about using LiPos generally
are these figures representative of standard servos too?I've just ordered one of these-
to run the 3 primary controls in the York, and also flaps and 2 retract servos-though unlikely they will all be moving at the same time!
Then I will need to disable the BEC input from the ESC, you said-by cutting the red (middle)wire?
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I am thinking of adding a 40 or 60 amp opto esc with a UBEC. A whole new ballpark for me, so I have posted a seperate thread to keep it clear.'
where, Shaun?
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Is this depron a wonder material? Can you make anything from it? How about spinners?
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They answered the phone to me last week.
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' but a simpler - and therefore better- common paractice is to either disconnect one BEC and let the other do all the work,'
errr-but how does the second esc get throttle input?
perhaps I'll get a UBEC then.
can you tell me how to test the QC capabilities? Ta
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ps-best of luck with the rebuild-a lovely looking model. Just promise me you'll put some u/c doors on her!!
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I am interested to hear the outcome of this-having just bought a Spektrum radio!
I have to say (from my limited knowledge) that it didn't sound like 'brownout' as previously described-in that the model seemed to carry on flying-unchanged-for several more seconds-I thought the throttle should cut? And even without 'quick connect' it should re-establish contact within 3-4 seconds?
Also, I don't know when you bought your radio Shaun-recently I guess as that was, what-your third flight with it? but my handbook says that all receivers manufactured after 2007 have the quick connect feature..have you tested the radio since the crash?
On the same topic-does the fact that I will be running a pair of ESCs both with BEC into a Y lead to the rx mean that I have doubled the current available to the servos, thus halving the chances of this 'brownout' phenomenon? Or halved the current? Or not affected it at all?
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There are some touchy people around...seemed a perfectly reasonable explanation to me.......
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oops
thanks Alex....now where's that dunces hat?
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Pictures please Glenn!
I'm interested in this new 'depron' stuff.....
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slightly different query....no aileron/rudder mix? is this usual on a modern computer radio?
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'Incidentally failsafe on the spekky dx6i and 7 sets only actually operates on the throttle channel - ALL other channnels will simply hold their last known good position....actually positioning any of these channels during binding is a complete waste of time.'
well, selecting 'gear up' and rebinding has fixed it....
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actually not the twinstar being discussed here, Frank, but the York.
thanks for the heads-up tho
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'by the way what model is it?'
scratchbuilt avro york-as per the pic!-6' span, 4x speed 400s
I always switch on the tr and then WAIT at least 10 seconds before switching on the receiver - try that method after you have re-bound
me too-though not necessarily 10 seconds...
'Incidentally failsafe on the spekky dx6i and 7 sets only actually operates on the throttle channel - ALL other channnels will simply hold their last known good position....actually positioning any of these channels during binding is a complete waste of time.'
kind of shoots my theory down....
let you know later how i get on
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Hi Alex
the retracts work fine, on the retract switch, on 'gear' channel
i know what you mean about the servos 'hunting' on initial switch on-all the control surfaces wiggle briefly-but this is a complete cycle.
I'm thinking what's happened is that on the initial 'bind' (done with just the rx and a slave esc on the bench) i had the u/c selected 'down' and the rx now sees that as the 'failsafe' position-so when switching on, before the rx picks up the tx signal (which seems to take a couple of seconds) it is selecting 'failsafe down', then picking up the signal and retracting the gear again...
can't prove this right now as had to come to work (motorway drive very good for pondering these things!) but will try a 'rebind' tomorrow and post the outcome.
cheers
Martin
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and then I'll replace them with some the new brushed lipo specific 400's that Puffin Models are stocking
or aren't, in fact....
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Thanks Frank.
I've got a u/c on my twinstar too.....
I'm aware of the possibility of the esc reverting to 'full' but I think as long as i don't switch the model on with throttle set to full (after 'teaching' the esc where 100% is) the esc will continue to just think it's got 75% (or whatever) throttle on the stick-essentially, all one is doing with the 'throttle travel' adjustment is putting an electronic 'gate' on the stick movement-as i understand it?
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got a brand new spektrum Dx6i-and all seems hunky-dory....
but why, when i switch the aeroplane on (tx already on) does the u/c cycle through extension/retraction?
is this to do with binding to the model or something?
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but I'm a 'heavy' and if I can't fix something with a hammer then I tend to struggle....
you may remember my 'nicad to lipo upgrade' thread from a few days ago, about the issues of running speed 400 motors on a 3s lipo pack-well. my cunning plan, having upgraded from my trusty JR Propo Core (1985 vintage!) to an all singing and dancing computer 2.4ghz spektrum-is to simply reduce the 'WOT' position by using the 'servo travel' adjustment on the transmitter, so that the static thrust measurement (I don't own a fancy wattmeter, but do have kitchen scales!) is the same as produced by the old nicad packs.
Well, it seems to work-winding down the throttle travel from 100% to 40% reduces the static thrust to previously seen levels, and the motors run correspondingly cooler.
Finally, to the question...
One of the suggestions for reducing current draw was to change to smaller dia/pitch props-but would I be correct in assuming that if I did that, I would simply have to compensate by increasing the volts and current draw would remain the same? In fact-are 'current draw' and 'static thrust' essentially measuring the same thing?
And....if running at this reduced power setting-does that also mean the speed controllers are handling less amps?
Cheers in advance
Martin
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know what you mean about the rain.....
if as you say your model 'glides dead flat' power off, then you need only a small amount of thrust to maintain height-you obviously have an excess, so enjoy!!
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well, indeed! as you increase speed (forward stick/down elevator) so you need to increase throttle, and vice versa...that's flying as opposed to driving!
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