Nigel R
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Posts posted by Nigel R
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22 hours ago, Martin Harris - Moderator said:
There’s a good argument for routing the current draw away from the receiver bus in cases like this, especially given the small conductor size supported by standard servo plugs but we’re straying into larger model territory.
I agree. Servo connectors are the very opposite of heavy duty.
A Y lead and separate retract battery achieves the necessary separation perfectly well, and isolates the likely mechanical failure away from the main flight controls.
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On 17/02/2024 at 17:37, steve too said:
Indeed. Brownouts happen when the supply voltage drops below the reset voltage of the receiver's processor. This was a problem with the first Spektrum receivers (e.g. the AR7000) which would do a full signal acquisition scan on power up. It was fixed back in 2008 with Spektrum's Quick Connect firmware but the story will not die.
The only time that I have had a cell fail in a receiver pack, it was a LiFe...
It was also fixed by improving the tolerance of supply voltage in the next generation of receivers, if I remember rightly what I have read about the subject.
If I'm honest, there was no way a healthy 4 cell nimh pack (and a decent switch with good wiring) would have dropped below the original operating voltage range - providing the pack was not overstressed.
Of course, one could take a knackered old 4 cell pack, a dodgy old switch with dirty plugs or an icky solder joint, and combine them with some fancy new high power digital servos - trouble is being requested and would no doubt be delivered.
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Cannot add much to the advice above. Cleanliness is everything. Copper from mains cable, bind nearly as you can.
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Note, pva, not all pva is created equal, in that topic much has been written by folk more knowledgeable than I.
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I'd be a little careful before flinging legal language around.
Did the ESCs need any mod before use, eg soldering on a connector?
Did they genuinely fail or were they broken, eg by connection with a faulty motor. Or through a faulty power path that put voltage spikes into components that could not handle them? Have they been subjected to damage from a faulty soldering iron that has caused the failure under stress of real use?
I'd identify the common factor first.
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2 hours ago, simon barr said:
I swapped from NiMhs to lipos as receiver packs simply for practical reasons... It only takes less than an hour to charge, and I would be charging flight packs anyway, so can be out flying (power or glider) with just a couple of hours notice.
Given that the low discharge Nimhs lose so little charge over time anyway, and can be fast charged in an hour from flat, I'm not certain I see a practical advantage of a lipo.
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I use a set of fittings similar to those PDB posted.
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My 4 button imaxB6 clone came with an adaptor lead that fits a clip-on glow starter.
Maybe you also have one already, still hiding in the box for a charger?
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4 cell Eneloopp nimh for all my IC airframes.
Quality cells, technically simple answer, right volts for my JR servos, pack weight is not an issue at .40 size glow and upward.
I use a simple trickle charger.
2 cell lipo would also work if you are kitting out with new servos that cope with the voltage.
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The SF do also have plating issues. Buyer beware, etc. I have several 61 SF bought from second hand sources that had peeled liners. I read that Nickel plating requires a higher degree of both workshop cleanliness and chemical bath purity and OS struggled with that. The other manufacturers were not restricted by tighter environmental laws regarding chrome.
Of course OS did also use ringed pistons, I guess that wasn't fashionable, very few second hand engines have ringed setups. I do have a ringed SF, they are out there, and it runs just the same as the ABC one. The heli engines are a reasonable source of ringed piston/liner combos, if needed.
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Keep your eyes peeled for a nice 61SF on ebay, would be my suggestion. They are, as you noted, very nice.
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Hmm. Sukhoi, whatever flavour, will fly at Reynolds far above what a Wot 4 does, apples and orange etc.
One thing Chris Foss was good at was marketing and protecting his IP. Pinch of salt etc. What did this testing consist of? What results are there? What controls were in place to ensure single changes were tested and measured?
I remain unconvinced that he simply didn't draw something round a handy curve and claim it was the best thing since sliced bread...
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I believe the glider guys are way ahead there Peter, see work by Drela and previously Selig for instance.
With a power aircraft we completely swamp any differences in performance with excess power.
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8 hours ago, Robin Colbourne said:
it had a slightly of concave section between the spar and aileron to make the aileron more effective.
I'd love to see Chris Foss' supporting data for this claim...
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Faced with the prospect of cutting all those ribs, I returned to the tailplane and instead cut and shaped and tapered the elevator. This was then hinged and bevelled. Whilst I still have some shaping of the fins and rudders to do I think I am almost out of excuses to avoid cutting the wing ribs.
As usual for me, the elevator has harder wood at the hinge line and a hard point to take the screw on control horn. The rear of the elevator is simply soft sheet.
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You could take the 4-max setup from the Sky 40 and use that, it's a very similar size/weight trainer airframe.
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On 10/02/2024 at 21:24, Jon - Laser Engines said:
Ah yes well its a complicated attempt to save my SCASP 400 radial. One of its main issues is the valves. Some clown decided it would be fun to use valves made from cheese. And not a nice hard cheddar either, more of a baked camembert. In any case, the valves wear at an alarming rate and loose their seal after about 2 hours of running. I am bored of fixing them, so i thought 'would laser valves fit?' They do, the heads are not a bad size and they seal well, but the stems are too short for the existing valve guide and spring setup. So, what if i ream the heads and fit Laser valve guides, valves, springs etc...would it work? can i achieve the required accuracy?
This is why i plan to experiment with a busted head before i mangle the ones on the engine.
If i can fit the new valves, do i then need to make new rockers or can i shorten the rocker shaft mount post in the head? I also need to fix the rear crank bearing mounting plate as the bearing just falls out. I need to fix the front housing as the front bearing also just falls out, and....i forget, there is something else i need to do but cant remember what it is.
Either way, there is much to do.
EDIT. Wait, i remember. Make new piston rings and/or, see if i can make new liners and fit current Laser pistons and rings to increase capacity and performance.
Can't help but think the right answer is "5 Laser 80 cylinders fitted to the ASP crankcase which might as well be replaced because the valve gear is different which sort of gives you a five cylinder Laser"...? 😈
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welcome aboard!
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Answering the exam question, no, I don't think most people push themselves outside their comfort zone very often, if at all.
8 hours ago, Brian Cooper said:Those precious hours cannot be built on a simulator.
I would disagree, with the caveat - simulator hours are definitely worth something - but not as much as the real thing.
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Thanks Nick.
It's a touch tight, I'm aiming to open up the slot a little, later on. As you can see I'm going to have to be really careful to get the hinges lined up when it comes time to glue them. The cocktail sticks are an aid to keeping things nicely aligned and might do double duty as slight reinforcement to the joint.
External fairing - hadn't thought about it yet, but it's a good idea.
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I got a few shots of the rudder assembly to better show the thing moving around
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K+S do thin wall brass tube in short lengths, if you need to sleeve the wheels.
A single torque rod on each wing is my method. As per original Chilli Breeze plan https://outerzone.co.uk/plan_details.asp?ID=13801
Your test stand is too complicated 😄 Mine just have the engine screwed direct to a piece of thick ply!
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That could work (and yes, the nacelles will go back to the main spar).
That said, I'll also be running some thin glass right out past the nacelles this time - I'm hoping that, coupled with the half ribs, will be enough to toughen up the LE root area
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Swap it out for the Irvine 46, quick!
Powering the Rx
in Beginners
Posted
Apples and oranges, and not the kind of scenario I described.
Take off damage lead to mechanical failure with a subsequent electrical overload. As noted, separating the retract power supply would have mitigated this risk and allowed a controlled landing.