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Member postings for Martin Harris

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

Thread: RCV engines
17/05/2020 17:43:52

My 91CD powers a traditionally built and venerable 64.5" Sterling Models Stearman very adequately for more than scale performance. A quick Google shows that it was designed for ".56 - .65" engines - presumably 2 stroke glows given the 60's origin of the design and that there are many recommendations to use .90 - 1.10 4 strokes so that would suggest the power output of my example at least keeps pace with traditional engines.

17/05/2020 14:58:54

Interesting. I was always under the impression that they were made in China long before Weston took over. It seemed odd that there was never any mention of where they were made on the packaging or published literature although there were references to being designed in the UK. Were these perhaps prototypes or being assembled from batches of components produced elsewhere? Did you see the parts actually being made?

Thread: Smoking....
17/05/2020 14:49:21

I bought a Wattmeter, branded by a very well known chain of model shops and stopped using it once I realised that there was little relation between the readings displayed and reality. I now use telemetry sensors on new electric models to check that components are operating within reasonable limits, both on the ground and in flight.

And yes, I'm another retired BT engineer (with over 41 years service, man and boy). I was too young for some of the very generous release schemes but I managed to escape to early retirement at the age of 58 what was becoming a very different micro-managed culture of fear environment which was so alien to the probably somewhat over-lax days of the 70s and 80s before the effects of the Civil Service origins diminished in the face of privatisation and competition. I moved in to the very different environment of internet and private network provision in the early days of commercialisation of the internet which was interesting and challenging until it was absorbed into business as usual and progressively de-skilled.

Thread: Flaps
16/05/2020 17:56:42

I must say that balancing the drag from flaps with throttle gives very satisfying approach control - the instant and so controllable response to varying the throttle on the approach path is almost hypnotic at times.

Edited By Martin Harris on 16/05/2020 17:57:07

Thread: Coffin dodger needs help.
16/05/2020 14:20:51
Posted by Barrie Lever on 16/05/2020 10:13:58:

I get the feeling that you might not have any of the equipment that I mention, so you are in what I would call the 'Sahara situation' meaning out in the middle of nowhere and no tools.

In this case I would make the connections by simply twisting together the bared back cables and wrapping tape to insulate, I am not advocating this as a normal fix but under current conditions getting help is going to be difficult.

Solder has a relatively high resistance and should be used primarily to hold together a good mechanical joint. If I were in this situation, I would consider a dob of epoxy over the wire twist to seal against moisture and air ingress leading to oxidisation.

Thread: Has anyone heard from Jeff2Wings ?
15/05/2020 15:51:40

It may be that one or more former members have "thrown their toys out of the pram" and requested all their posts to be deleted. I'm fairly sure this has happened in the past - IIRC a member posted asking for this to happen and a day or so later, similar messages appeared to replace his posts.

No doubt it involved a lot of hassle for our hard working moderators!

Thread: Flying over private land
15/05/2020 11:18:44

Thanks Steve, I was beginning to wonder if I'd remembered it correctly. For the benefit of others interested, this is the relevant exemption from EASA regs.

a) The Civil Aviation Authority (CAA) permits, under SERA.3105 and SERA.5005(f), subject to the condition set out in subparagraph (b), an aircraft to fly elsewhere than as specified in SERA.5005(f)(1) at a height of:
i) less than 150 metres (500 feet) above the ground or water; or
ii) less than 150 metres (500) above the highest obstacle within a radius of 150 metres (500 feet) from the aircraft.
b) The aircraft must not be flown closer than 150 metres (500 feet) to any person, vessel, vehicle or structure except with the permission of the CAA.

So, my amateur interpretation is that over clear ground or water, there is no minimum height but as soon as a person, vessel, vehicle or structure is encountered, there is a 500 foot distance and height "bubble" in which the aircraft is not allowed to fly.

15/05/2020 10:42:08

I'd hesitate to argue with those credentials but I think Cuban is right. I always understood that the 500' rule was distance from a person, vessel, vehicle or structure, not necessarily altitude - although maintaining 500' AGL would more or less guarantee compliance except in the case of unusually high buildings or structures.

Of course, things may have changed since my day - especially with the advent of EASA.

Edited By Martin Harris on 15/05/2020 10:59:06

Thread: For Better or for worse
14/05/2020 13:37:19

On a related note, I nearly lost my car a couple of years ago due to wondering if I'd loaded my spare transmitter for buddying a friend. I had set off to the field and after half a mile or so got that nagging feeling that I didn't recall putting it in the car. I'd just turned on to a hill so waited until I'd got to just before the top so that I wouldn't cause a blind spot hazard, pulled over and jumped out to have a quick check.

As I approached the back of the car, I became aware it was moving and quickly got behind it to stop it moving. It quickly became apparent that I wasn't going to be able to hold it and I realised that I had to get into the car to apply the brakes before any more speed built up. I pulled open the driver's door and attempted to jump in - but the door took my standing leg and I was deposited bottom first onto the road. A last gasp grab at the B pillar was successful and with a despairing scrabble and heave, I found myself in the driving seat and brought the incipient disaster to a halt.

After dealing with the realisation that I could have ended up with a broken leg and/or had the car career down the hill, maybe ending up causing a serious accident, I parked properly on the level, reapplied the parking brake and found that I had indeed left the buddy box in my front garden.

Coincidentally, a week or so ago, I went outside to run the air con for a few minutes to lubricate the seals and noticed the car moving on the very slight slope outside my house. As my wife had given the car a run earlier, I thought "silly woman's left the brake off" and applied it. As soon as I blipped the throttle to raise the RPM it moved again! My car has what I consider to be an unnecessarily complex "electronic parking brake" instead of a proper handbrake lever and a quick diagnosis revealed that if the engine was running (in neutral), the slightest nudge on the accelerator pedal caused it to release! This is not something detailed in the handbook and the car is supposed to sense the gear selection when it enters the "hill start assist" mode - whatever use that might be.

I'm now wondering if this was the reason my car rolled away on that hill - at the time I put it down to not having held the operating button for long enough but had I knocked the accelerator pedal slightly as I jumped out of the car, it would fit the circumstances.

Spookily, while I was typing this, I got an email from the manufacturer following up on the report I raised to VOSA querying the safety of this operating system. I'm sure someone on the forum will want to tell me that I should have stopped the engine, engaged a low gear and turned the wheels into the curb but we don't always follow best practice and I have learnt lessons from the experience.

Thread: The big question, WHEN
12/05/2020 13:03:46

Odd. Hopefully not tempting fate but we must be doing something wrong as our membership seems largely supportive of the committee and willing to listen to reasoned argument. There's no lack of grey hair though.

Thread: Flair Pupppeteer
11/05/2020 14:12:08

The C of G position marked on a plan is a guidance really. Advocating hanging nose down is the designers way of ensuring any error is on the safe side. In full size practice, there is a permissable range specified so looking for perfection to a few thousandths of an inch is overkill. You will see a range marked on a minority of plans to reflect this but many designers simply mark what they think is likely to give reasonable results. We are really all test pilots due to all the variations in builds - even ARTFs can differ between examples - so the principle of starting at a safe position and working back to the "sweet spot" is best.

Thread: Overlander. Which genius
11/05/2020 14:00:54

I changed from bullets to Deans many years ago and they have been reliable for my electric toys - I'm afraid that I still prefer my larger models to have IC engines so the current carrying limitations haven't concerned me.

In my bullet days, I always adopted the male/female pair principle but took the precaution of adding heatshrink banding just behind the bullets around both leads to make it virtually* impossible to connect the battery terminals together inadvertently.

*I appreciate that there's always someone who can circumvent any solution!

Thread: How to smooth the glue lines between balsa sheeting?
11/05/2020 01:23:44

I can't say I've ever had a problem sanding planking fixed with aliphatic - I wonder how long it takes to harden completely - not just the surface? Perhaps leaving it a bit longer before sanding might help?

Thread: ungluing
10/05/2020 18:09:28

On a more sensible note, prompted by gangster, I've remembered that I've used a thin steel rule for separating parts - Poundland do a particularly thin gauge 2 foot one for...a pound.

10/05/2020 17:16:17

Get one or two people I know to fly it after the lockdown. They never seem to have much trouble dismantling their models quite soon after take-off...

Thread: Shaft reversal
10/05/2020 14:24:00
Posted by RC Plane Flyer on 09/05/2020 18:50:40:

Was John Emm's the manager of Puffin Models who were agents of a brand of special Brushless Motors ??

John and his wife Sandra owned and ran Puffin Models.  Sadly, they sold the business and I think it has now closed - if my experience of the new service was anything to go by, I'm not terribly surprised.  Customer service under John and Sandra was second to none.

Edited By Martin Harris on 10/05/2020 14:28:34

Thread: Binding undercarriage using solder and wire
09/05/2020 11:51:08

Wingman's point is, in my opinion, the key [apart from scrupulous cleaning] to successful soldering. Whether soldering electrical components, structural points or tinwork, the only time you should touch solder to the iron is to tin the tip. The wires or parts being soldered must be hot enough to melt the solder when it is touched to the metal being soldered. Fresh tinning aids heat transfer to the components being soldered.

I picked up an old fashioned "lump of copper on a stick" soldering iron which is useful for heavy jobs but although many will say they can't cope without a large heat retaining capacity, my 50 year old Weller instant heat gun copes with surprisingly large joints.

Edited By Martin Harris on 09/05/2020 12:02:26

Thread: CAP1915 UK Drone Corridors - Future impact on model flying?
09/05/2020 11:38:04

We certainly checked them at my gliding club some years ago when I was active, which were received daily by fax [remember them?] Mistakes happen, but I would be surprised if full sized pilots regularly ignored them.

Happily, it's far easier to get NOTAMs in this internet age - you can get a daily update to your email inbox every morning.

Thread: Approaching a farmer to ask for a flying field
04/05/2020 13:48:04

Well, I keep getting the M$ message - try this link instead.

I'm a little curious - you say the local BMFA [club?] is "mostly indoors" - does this mean they have access to a flying site but it's not used much? If that's the case, can't you use it if you join - you'll be no worse off than going it alone if nobody else turns up!

Whereabouts are you? There could be forum members with local knowledge...

Thread: Power consumption on multi engined model
03/05/2020 15:43:38

Just thinking out loud - have you considered a higher cell count to reduce the current required?  The result could reduce both weight and cable management issues along with reducing losses due to voltage drops across the various connections at higher currents.

Edited By Martin Harris on 03/05/2020 15:50:27

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