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Member postings for Peter Christy

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

Thread: Durafly Spitfire 1 and 24
25/04/2017 08:24:14

Trevor, that's a good write up with some interesting tips! I completely removed the gear doors on mine, which helped a bit with the nosing over problem. However, the combination of small wheels mounted close to the CofG does make it very prone to tripping up on landing, no matter how careful you are. I must try that tip with the washers!

I broke the prop on mine on the first landing! Not being too sure about the tip-stalling, I brought it in a bit fast, just to be safe. That was a mistake! I've only broken one more since, but ordered replacements in pairs to mitigate the postage costs. The props seem to have come down in price since I broke the first one!

PS: Love the car, Cliff!

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Pete

Thread: Irvine 53 carb setting
21/04/2017 12:37:07

I should've gone to Specsavers........! blush

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Pete

21/04/2017 10:54:42

Steve H's method is as good as any for setting up an unknown carb. It will get you pretty close to the desired setting without too much subsequent fiddling!

That was how I was taught to set up a carb by an acknowledged expert years ago, and it works!

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Pete

Thread: Horizon Hobbies
20/04/2017 14:32:16

Well, perhaps my clubmate and I were just unlucky and caught the UK staff just after they had received their redundancy notices!

If the German operation is living up to the standards of the old HH, perhaps I ought to try sending them that receiver, which is now acting as a paper-weight!

The problem for HH, as I see it, is that good reputations are very difficult to build, and very easy to destroy. This is especially true when there are alternatives available that afford either better service or cheaper products - sometimes both! I ended up getting an Orange receiver, which whilst it may not have the backup that HH once boasted, is cheap enough not to matter. Oh, and so far, it has behaved flawlessly......!

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Pete

20/04/2017 13:00:00

I forgot to mention the episode with the B'n'Fly Pitts special as well, where 'phone calls led to me being shunted around an interminable automated 'phone system, whose sole purpose seemed to be to prevent you from speaking to a human being, emails and letters being ignored, etc. I finally did get that one replaced (the entire elevator chain - including the gyro - decided to reverse itself between flights!!!)

My fellow club member, who had one of their "beginners glider", which every second or third flight would lock everything hard over and spiral into the ground, never did get it fixed or replaced. He gave up in the end. It was definitely an airborne fault, as it did it with several different Txs, including my DSX-9, which has performed flawlessly for years.

So, no, I'm not just basing it on one incident. I was simply trying to be brief, and overdid it!

I also used to be involved in manufacturing and repairing radio gear many years ago, and remember a guy turning up at 9 o'clock at night, with a set that was at least fifteen years old and had a faulty stick pot. We replaced it while he waited! We also replaced, at less than cost, a receiver that had ended up in the sea, after the glider it was in was attacked by seagulls! We used to pride ourselves on fixing anything we'd sold and keeping customers happy.

Sadly, this approach is seen as old-fashjoned, these days.....

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Pete

20/04/2017 12:14:30

You had better luck than me, then! I also returned an out-of-warranty receiver that had suddenly stopped working. This was to the UK store, a while before they closed.

All I got back was the same faulty receiver along with a rather curt note saying it was no longer supported!

I'd only previously had to return one Spektrum item, a DSM-2 Tx module that stopped working. It was promptly replaced by a newer version, confirming reports I had heard about their excellent service support.

My most recent experience, and those of another club member, have persuaded me that now HH are to be avoided at all costs.

Its a real shame, after the efforts the original team put in, building such a good reputation.

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Pete

Thread: Irresponsible ' drone' retailers
19/04/2017 18:47:06

I think you'll find that references to the BMFA as a "Governing Body" refer to its duties for *competition* purposes. Competition flying for all aircraft comes under the FAI as the international body controlling the sporting side of things, but this has nothing to do with any *legal* obligations, which fall under the CAA. The FAI delegates national bodies - such as the BMFA - to be the "Governing Body" for competition purposes.

The CAA exempts model flying from much of the ANO, and recognises the BMFA as representing model flyers, but the BMFA has no statutory duty or responsibility for model flying, as far as I am aware.

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Pete

Thread: Dual elevator servos and flap mix - AAARRGGGHHH !
19/04/2017 08:45:23

Why not simplify the problem by using a "Y"-lead for the two elevator servos? That way, you would only be using one channel for the elevator function, which would make mixing in flap trim much easier.

I use a "Y"-lead for models using two aileron servos - one in each wing - and not had an issue with it....

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Pete

Thread: FrSky Taranis - user chat
18/04/2017 09:52:33

Chris: My reasoning for saying apply rates and expo at the mixer stage is as follows:

For simplification, lets say the resolution of the system is 1 part in 100. If I mix three functions together in equal measure, then the resolution of the output is only 3 parts in 100 (there is a possible error of 1 part per 100 in each input, so the potential error on the output is the sum of all three).

Now, if you reduce the inputs to 50%, the resolution is now only 1 part in 50 - or 2 parts in 100. If you once again do the same with three separate inputs and mix them all equally, using the same logic, your resolution has now dropped to 6 parts in 100.

Its generally considered best practice to do any arithmetic at the highest resolution possible, and then wind it down at the end of the process as required.

However, I don't know in detail how they handle all this in OpenTx, and am relying on what I was taught in computer classes back in the days of IBM mainframes and DEC PDP-8s, so my understanding may be out of date!

I do know that the Taranis uses a 32-bit processor, so it may well be that any cumulative errors are within the resolution of the servo at the end of the day anyway, even if you process things the wrong way around!

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Pete

Thread: Irresponsible ' drone' retailers
18/04/2017 09:40:21

Personally, I'm an optimist. Drones are simply this year's CB craze. We all thought CB radio was going to kill RC flying in the UK, and for a while it did cause quite a few issues.

But the craze passed, and we carried on much as before.

I suspect the same will be true of drones. For a few years, their use by the non-modelling public will cause us some grief, but then something new will come along and they will swiftly be forgotten.

27 MHz is nearly as quiet as 35 MHz these days......!

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Pete

Thread: FrSky Taranis - user chat
18/04/2017 09:07:35

WARNING: Be careful when using a Taranis (or any OpenTx system) to set up an i/c helicopter. There is a trap for the unwary that can lead to a (very!) hot start!

I recently built a NOS Schluter HeliBoy, and equipped it with FrSky gear that I've been using for some time. I had selected the throttle trim to "idle-only" and programmed a "kill-switch" for the engine. I was using a five-point curve for the throttle, and during test flights, I needed to increase the three mid-points to get enough head speed in the hover.

When I re-started after carrying out these adjustments - which were only slight, around 5% - I was treated to the delights of a VERY hot start, and there ensued several seconds (but it seemed longer!) of panic whilst I tried to shut it down!

Moving the mid points on the throttle curve had significantly increased the idle speed.

There is a solution, and that is to apply the curves at the input stage, rather than in the mixers. For a full description of the whole saga, plus the solution, see here:

**LINK**

I don't think this is an issue with OpenTx per se, but to those coming from other brands it was unexpected behaviour! It certainly caught me out!

It is unlikely to happen with an electric powered heli, as the ESC will usually refuse to arm unless the throttle is fully closed. Having said that, I usually power up my electric models with the "kill" switch engaged on the Tx, to prevent accidentally opening the throttle before I'm ready! Releasing the "kill" switch could also produce a sudden and unexpected spooling up!

I was caught out primarily because it is considered good practice to apply rates and expo at the mixer stage, to ensure all the arithmetic is carried out at maximum resolution. Since a curve is a variation on a rate, I assumed that the mixer would be the best place to apply a curve too.

In this case, I was very wrong, and gave myself quite a fright!

Golden Rule: Apply throttle and pitch curves at the INPUT and rates and expo at the mixers!

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Pete

Thread: Fisher Redshift R60
05/04/2017 15:32:48

Gangster: If you send Just Engines the measurements of the exhaust port (they show what's required on their website), they'll tell you if it will fit. I would be very surprised if one or the other would not fit.

Is it a Schnuerle ported engine or a cross-flow? A cross-flow will have a deflector on the crown of the piston (Schnuerles are flat), easily observable through the exhaust port. If its a cross-flow, the 40/50 size BCM should be quite adequate. A Schuerle ported 45 is pretty much the exact equivalent of a cross-flow 60.

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Pete

05/04/2017 09:38:40

I bought a BCM strap-on silencer for my SuperTigre .45 when I managed to damage the original in a "heavy" landing!

**LINK**

(Scroll down to bottom of page)

They do two sizes, one for 40/50 size motors and another for 60-90 size. Very easy to fit, and pretty quiet too.

As an aside, I always use 5min epoxy as a gasket. Never had a leak or silencer come loose since I started doing that some years ago!

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Pete

Thread: Small PAW advice
28/03/2017 09:04:44

Cheers, Jon! Yes, fresh diesel smells wonderful! Its the exhaust residue - usually a black oily goo - which isn't so good!

I agree that high nitro fuels do tend to promote rust, and I'm always careful to run my engines on 16% bone dry at the end of a session. Its less of a problem if the engine is in regular use.

As another aside, I managed to persuade MT to make some Bekra straight - no nitro! They don't advertise it, but its perfect for Super-Tigres, and other engines that don't like nitro!

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Pete

27/03/2017 19:56:31

That's a very interesting post, Jon. For glow engines, I switched over to fully synthetic years ago, and have never had any issues. I've used Bekra heli fuel in all my engines (heli or not!) for many years without any issues. Ben Godfrey (who formulated it) was an old friend of mine, and had come up via racing motor bikes. There wasn't much he didn't know about two-strokes!

Interestingly, when Bekra came out at first, I believe it was only 15% oil. It certainly ran very cleanly, compared to what we had been using! IIRC, it only got upped to 18% because OS were threatening not to honour warranties on engines run on less than 18% oil!

As a matter of interest, what synthetic are you using in your diesel fuel? I ask, because I know that not all oils dissolve equally well in all fuels! Castrol used to do two different castor oils - one for petrol and one for methanol, and heaven help you if you picked the wrong one!

One of the worst things about diesels is the horrible oily residue left by the exhaust. It seems to get into everything, and the smell lingers for ever! Anything that is easier to clean off has got to be an improvement....!

As an aside, I recall many years ago, Mick Wilshere of Super-Tigre fame had a friend who worked for Shell. This "friend" recommended some new synthetic oil they were working on, which he reckoned would be ideal for model engines. It was! Mick mixed a few gallons of the stuff, and handed it out for people to try. No engine problems whatsoever, but the STENCH was unbelievable!

Even transporting a tightly sealed bottle of it in the car left a stink that lingered for weeks! And when it was spread through the atmosphere by a screaming two-stroke......

Well, I leave you to imagine why it never caught on.....!

disgust

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Pete

27/03/2017 18:00:56

Jon: That's interesting that D-3000 is 20% castor. I was under the impression that it was less than that, but I've just looked at the MT website and you are quite right! (They didn't used to publish the formula "back in the day"!)

I would have thought 20% would be more than enough for any engine, but I'm not a real engine expert! I know how to set them up and maintain them, but the finer points of fuel formulation are outside my area of expertise!

I know my PAW 1.49s loved D-3000, and throttles superbly on it. Maybe I ought to switch the 80 to it after all! It certainly starts more easily and is less critical on the needle valve on it.....

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Pete

27/03/2017 11:44:04

I've got a PAW 80! Great little engine, but quite fuel sensitive, and those little 6x4 props have *really* sharp edges - even when sanded!

Mine is in a half-size Super 60 (30" span). There's some video of it in action at the PANDAs event last year, about 1'30" in:

Mine has a muffler fitted, and it flatly refuses to start on D-1000 (the "easy-start" diesel fuel!), but goes like a dingbat on D-3000 (the contest stuff!)! However, the general advice is that D-3000 doesn't have enough oil for plain bearing engines, so I've compromised on D-2000.
Its quite sensitive on the needle (as you'll see from the video) but once sorted, it pulls really well. I started off with it on a 7x4, which made it easier to start, but it pulls better on a 6x4.
I think they've re-named it to PAW .049 these days. What other changes have been made, I don't know.
Enjoy!
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Pete
Thread: Navy carrier landing
23/03/2017 15:40:44

The pilot certainly earned his salary with that one!

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Pete

Thread: RC equipment reliability
21/03/2017 14:32:07
Posted by MattyB on 21/03/2017 12:37:03:

Correct - the DSM and some first generation DSM2 RXs had brownout voltages in the 4.1-4.2V range. That proved well within the window of vulnerability if using an aging 4.8V pack as the power supply for high power/large numbers of servos.

And that hits the nail squarely on the head!

It never ceases to amaze me that modellers will spend months building a model, spend hundreds of pounds on RC gear, and then power it using a battery and switch that they pulled from the last wreck! angry

I used to have a friend who ran a model shop, sadly no longer with us. He used to sigh with relief when a heli flyer came in! "Why?", I asked him. "Because they think nothing of spending £100 on a servo, if that's what's needed! Fixed wing flyers argue about the cost of the cheapest servo / batteries / switches I stock, despite the effort they've put into building, and the amount they've spent on receivers and engines!"

I have to say that looking around some of the local clubs, I can see where he was coming from......! disgust

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Pete

20/03/2017 15:45:47

MattyB: An excellent summary! However, as one of those who came to the hobby before proportional control was actually available - analogue or otherwise - I feel duty bound to point out that we *had* to install our equipment carefully!

Reed and relay receivers (some had as many as 12 relays on board!) had to be mounted "just so", and with as many as seven wires going to each servo, heaven help you if your wiring was not tidy!

I suspect the sloppiness to which you refer (and I agree it is out there!), started when equipment began to arrive pre-wired, and ready to use "out-of-the-box".

devil

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Pete

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