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Member postings for Mark Powell 2

Here is a list of all the postings Mark Powell 2 has made in our forums. Click on a thread name to jump to the thread.

Thread: Sussex Models
27/08/2012 09:40:57

Modulation and compatibilty are different things. They probably implement if differently (coding, looking for 'best ' channels to start, different bind codes etc.) They use the same 'bought in' chip set, (not specifically designed for r/c, they are general purpose) and the modulation looks identical on a scope - I saw someones here for the Spektrum and tried them both myself. But the 'bought in' chipset only applies for the transmitter, the receivers are probably different. This is Multiplex an DMSX. DMS2 is different again.

Futabas Fasst is very similar, so we are told. Their S-FHSS is not

Edited By Mark Powell 2 on 27/08/2012 09:41:58

Thread: F27Q Stryker motor noise
27/08/2012 09:30:31

True, didn't spot that. Rubbing or bearings then. Or a loose magnet. I have found Axi's prone to that.. Possibly others too. Easy to fix with epoxy (only Araldite 24 hour 'precision' is any good). Tedious because you can only do about a fifth of a turn at a time or it runs out, so it takes several days, but not difficult. Have to clean it up a bit afterwards.

Rubbing, bearings, loose. There is nothing else.

Edited By Mark Powell 2 on 27/08/2012 09:31:00

Thread: First build, a cautionary tale
27/08/2012 09:02:42

It is Monday. Do not copy that fact as if it was your own.

Thread: F27Q Stryker motor noise
27/08/2012 09:00:04

If the motor is OK by itself then maybe the spinner or whatever is rubbing. But oil the bearings (as said) anyway.

May have got out of balance. This makes a BIG difference. Loosen the prop, give it a quarter turn relative to the motor and try again. Maybe another quarter turn and so on.

Thread: Elf and Safety think a Spitfire seat is dangerous
27/08/2012 08:54:07

Ben B,

My clever boss did that. At IBM we had a (very good) voluntary redundancy scheme. We 'important' systems programmers were all hault into his office and said as we were 'vital' we could neither apply nor know what the terms were. "I am going for a coffee, I should check what's in that folder on my desk. Can't be bothered".

But they don't pay museum attendants, or bosses, the 60K or so (fifteen years ago at least) a year that he got.

Edited By Mark Powell 2 on 27/08/2012 08:54:20

Thread: 7.4 v servos
27/08/2012 08:41:59

All Mutiplex stuff is good from 3.5 right up till 9.0 (the specs say so) and has been for years. And they don't bother with this 'HV' marketing stuff. Receivers, servos, accessories, the lot. Never exceed the manufactures spec with any receiver, servos can usually take a little more and won't mind . Some JR servos are touchy if the voltage is higher than the spec.

Thread: Battery Type
27/08/2012 08:25:15

Never gone wrong with 'Intellect' from Ripmax/HobbyStores. Thunder Power from West London Models are good too, and not as expensive as you might think. Thunder Power started all this lipo stuff for models. The Overlander 'Sports' ones are Ok but not brilliant, my models don't seem so powerful with them Suspect they are cheap because of thir high internal resistance, which is not easy to measure, though a wattmeter will tell, from the lower voltage under load.

Accutately measuring capacity is difficult. it might say '2200' on the pack but it all depends where the supplier starts from as 'discharged' and of course you don'y know. You just discharge them to your chargers idea of what 'discharged' is, which is probably different from the battery suppliers, and they read different.

And of course, every single charge/discharge cycle reduces them a bit.

You don't think the suppliers , assemblers, labellers or whatever actually bother to measure this stuff, do you? They just take the manufactures numbers.

Edited By Mark Powell 2 on 27/08/2012 08:27:27

Edited By Mark Powell 2 on 27/08/2012 08:30:21

Thread: Sussex Models
27/08/2012 07:03:12

I once worked in the 'service' industry. A real human being is more important to me that a ringing plastic telephone. When I became more 'important' and interviewed people in 'my' office I turned the phone off. I'm a bit scratchy about it, as in "Are you with them or with us?" Maybe because my wife is a mobile phone obsessive. SMC bad? Try my local doctors surgery!

Thread: Bending 2mm steel wire?
27/08/2012 06:48:53

You can even do the loops in thick retractable U/C legs with them. Replace the limp spagetti wires you get in the Asian rubbish. The American K&S wire is the best, even though it tends (for the UK) to come in weird sizes, but you can always find a 'near enough' one.

Thread: Mercury Models Aeronca Sedan conversion to RC and electric?
27/08/2012 06:06:47

The real one has a flat plate tailplane made out of welded steel tube, also wires from the tailpane to high up on the fin and the bottom of the fuselage. Mine has a sectioned tailplane because of the aerodynamic effects you state  (if you believe Bernoulli and not Newton, I go for Newton but curve it just in case) and because it looks nicer. Can't be bothered with the wires.

The 'more than scale' wing incidence on free flight models is the cause of the problem. I always reduce it on radio conversions, even on my Junior 60. You can compensate with elevator but it is a pain, and doing it with a throttle to elevator mixer can produce rather sudden 'bad effects' (five foot up, then one foot up and nose down) at low landing speeds when you wham the throttle open when your landing is baulked. New Forest ponies, in my case.

Mine has a one piece wing, the struts are just decorative. Makes it all much simpler.

If you have a two piece wing the free flight method is usually hopeless. My Airsail kit Auster has that and making a one piece wing is difficult because of the all glass cockpit. The Airsail wing/strut design is also hopeless, even though a quite heavy r/c design, so I changed it.. I used a very strong steel tension spring beteen two hooks. Your struts have to be good too. there can be unintended negative G sometmes and the fixing have to be secure even if the G is only positive. And the sruts stiff. My fixing is brass plates firmly attached to the main spar and to the fuselage. and the fuselage plates are carried throgh to its opposite number as it is all one piece. The struts are bolted on, none of this Kwiklink stuff. As for the struts they are the hollow airfoil section aluminium tube, stiffened with a 1/4 inch carbon rod (not tube) epoxied in. As I dont trust joining end fittings to carbon, at the same time I epoxied in a continuios 14 guage wire with loops on each end for the strut fixing bolts. Ten years old, with the occasional outside loop (on an AOP 9?)and nothing has broken yet

Aerobatics on a high wing plane. Build the Sig Citabria. It is excellent for what it is.

Dave Deadman's article was my original inspiration and that is what I scaled up the plans from. All the magazines used to have scaleable plans. They even made it an easy 'fractional' scale and told you what it was so you could do it. Not so 'commercial' then..

Edited By Mark Powell 2 on 27/08/2012 06:09:29

Thread: Curare Build
27/08/2012 04:46:12

These loops on U/C legs are a thoroughly ineffective design. They only do it because it is simple and cheap. It puts all the bending load (and there is a lot) on the U/C mechanism. And the U/C leg, after a hard landing or a grass takeoff, never returns to its proper position, you have to 'adjust' the leg yet again. Even more often if you have doors attached to the leg.

Leaving the loops out makes the load on the mechanism and its mount even higher, though you may 'get away' with it. .

The vertical loads, on take off or landing, are so small compared to the bending loads that they can be completely ignored - see the way the U/C block breaks on all these naff ARTFs. Backwards, not upwards. on landing, not takeoff, so the bending load is higher on landing, though of course there are loads on takeoff too. Not that 'which is the highest' really matters, as you have to deal with the highest anyway.

So I thought about it. On my Topflite Spitfire I mounted the U/C mechanisms each on  its own strong plywood plate hinged to the main spar and free at the rear, between stops. Between the plate and the top stop is a strong spring (two, side by side if you can't find a single one strong enough - they have to be stronger than you might think). The U/C leg can move back under stress by about 2 1/2 inches but instantly returns to its exact proper forward position when the load is removed. Not difficult to do - the stops are mounted in much the same way as you mount regular U/C mounting blocks, except one above the other rather than horizontal, and its hinge is a 'regular' one from B&Q. Join the blocks together so the springs are not trying to split the ribs or tear out of the foam all the time. Particularly useful on grass. You can do it on a noseleg too. Did it on my Super Star.

Did the same on my DH88 Comet racer twin too. That has 'backwards and forwards' retracts.

Edited By Mark Powell 2 on 27/08/2012 04:56:36

Edited By Mark Powell 2 on 27/08/2012 05:00:01

Thread: Battery Type
26/08/2012 20:53:14

I think all the huge range of modelling lipos are purchased from the same half a dozen manufacturers, assembled into packs, covered with heat shrink, labelled and sold. Of course these few original manufacturers offer variois 'C' ratings for various prices.

It's like nylon monofilment fishing time. Sold under hundreds of different brand names, and dyed different colours, at madly varying prices. As far as I know, there are only two manufacturers of the stuff, Beyer in Germany and one in Japan. They may be manufacturers I have not heard about, but only one or two.

It's like radio. Multiplex FHSS and Spektrum DMSX use the same chip set, 'bought in' from the same semiconductor manufacturer., National Semiconductor, IBM, Texas instuments, or whoever, and none of them designed specifically for model radio control. They are 'general purpose 2.4 GHz chipsets' that anyone can buy. The others do the same. My modern Samsung TV is full of IBM chips, some of them the  old 'Power PC' originally made as a joint venture between IBM and Apple, when you thought the IBM PC and the Apple Mac were rivals.

Edited By Mark Powell 2 on 26/08/2012 20:59:57

Thread: West Wing Beguine r/c build
26/08/2012 20:19:50

I recently bought a KMS motor at about £19 that is the same size and RPM/volt as the £50 Axi because I am fed up with Axi prices. If the physical size is the same, and a '22' motor will be, and the RPM/volt is the same, the plane won't know how much the motor cost smiley

Thread: Sussex Models
26/08/2012 20:06:16

Didn't know Spektrum had it soo. The Futaba sets are not selectable, you have to buy a different one.

Multiplex and Spektrum use the same 'bought in' chip set, and Mpx sets use the same modulation as Spektrums DMSX so I imagine thats why they both have it. But they are not directly compatible, probably for 'business' reasons.

Edited By Mark Powell 2 on 26/08/2012 20:14:02

Thread: Electric RTF For Learner...Advice Please
26/08/2012 19:51:40

Wasn't directed at you, a couple of guys earlier (I should have made that clear) said he recommended Wot 4s for everything. Except when he recommends Concordes....

Thread: Sussex Models
26/08/2012 19:42:00

If you fly in France most UK 2.4 sets are illegal as their band is slightly different. Multiplex sets , wherever you buy them, have a 'France' setting you can select. Don't know if others do. Ripmax have some 'Euro' Futaba sets, but you have to buy that verson, as it is not user selectable.

Edited By Mark Powell 2 on 26/08/2012 19:44:55

Thread: any ideas as to what this is
26/08/2012 19:36:07

So my bottle of Laphroag is in the post? smiley

26/08/2012 19:33:49

It was used by the RAF, often used to carry the 'brass' around, Dunno when but it is certainly a Beech 18, which is the 'base' name of all the versions.

Thread: Electric RTF For Learner...Advice Please
26/08/2012 19:29:11

Don't go on at CS. He mentioned 'scale', but didn't suggest what I thought he might (small ones are quike easy), get it wrong and they just stick into the ground (or the farmers cow) like a dart. rather than break

Mpx are good but a bit pricy.

Thread: any ideas as to what this is
26/08/2012 19:17:28

Beechcraft 18. I thought it was a Beech, so just Googled Beechcraft twins and there it was. It has a few other names too, depending on version.

Do I get a prize?

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