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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: Super Tigre S90k problem
27/02/2017 15:33:06

Dave Wilshere at Motors and Rotors may be able to supply parts for the original carb. What fuel were you trying to run it on?

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Pete

27/02/2017 13:40:16

Hi Martin,

Yes, Mick was always adamant that no nitro should be used in Super-Tigres, and mine - even the smallest - have run fine on straight.

The later STs did include a shim to put under the head, if you insisted on running nitro, but even then, they only suggested a minimal amount - 10% was the absolute max, IIRC.

The OS 4-stroke plug has a huge thermal capacity - it needs it in a 4-stroke - and would certainly help with an engine flooding up in the transition. However, setting the carb up correctly should also solve the problem, and the tip about pointing the fuel inlet nipple at the front mounting hole certainly improves the transition.

Funnily enough, I always assumed that Japanese engines would like lots of nitro - I usually run OSs and Irvines in my helis on 16%. But in recent years I found two that got very unhappy on 16%! One was an AirSupply 40, the other a GMS 25. Both got very hissy and spitty on 16%, and would not idle properly. Switching them to straight had them running like turbines......!

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Pete

Thread: Engine Baffle Design
27/02/2017 10:58:40

Cymaz: The only comment I would make is that you seem to have blocked off the airflow over the cylinder heads - the hottest part of the engine.

The airflow around the cylinders should be fine, given enough exit area, but I would be concerned about airflow over the heads. That's why heli engines tend to have massive heatsinks on the heads - to keep the heads cooled in a restricted airflow (fans notwithstanding!). Notice how Gary's ducts include the heads in the airflow.

Just a thought.....

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Pete

Thread: Super Tigre S90k problem
27/02/2017 09:47:31

In addition to the above points, the other question is what fuel are you running? Super-Tigres were designed to run on "straight" fuel ie: NO nitromethane! Unless you shim the head, it will not run properly on fuel containing nitro.

They were also designed to use long-reach plugs rather than the current short-reach types, though this doesn't make much difference to the running. It just means that if you later fit a long-reach plug, the bottom of the thread will be full of carbon....

I'm also curious as to why you changed the carb? In my experience, the ST carbs, properly set up, as as good as you will get.

One tip: If you go back to the ST carb, rotate the spraybar so that the fuel inlet nipple points at the front mounting bolt hole. This increases the fuel draw in the mid-range and gives a better transition between idle and full power. Otherwise the setup is just the same as any other twin-needle carb.

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Pete

Thread: Starting a motor for the first time
26/02/2017 15:47:38

Depends on the engine! In days of yore (ringed, cross-flow engines), a couple of tankfulls quite rich, followed by leaving it on the rich side for the first few flights was considered the norm. The main thing is not to let the engine labour or overheat.

Modern engines usually require far less running in. In particular, ABC engines are probably best run-in in the air (better cooling than on a stand), slightly under-propped (prevents over-loading) and just a tad rich - definitely not slobbering! Keep the flights short at first.

Those of us who fly helicopters don't have the luxury of being able to run them in in the recommended way. We usually just bolt them in the airframe, leave them a tad rich for the first few flights, and keep initial flights short. Never seems to do any harm!

Just as vastly improved manufacturing processes means that modern cars need little if any running in ("Don't tow a caravan for the first 500 miles, sir!", so most model engines require little running in compared to the motors of yesteryear.

As I say, a tad rich, keep flights short, and don't over-load it, and it will bed in in no time! wink

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Pete

Thread: Solarfilm ClearCote......
26/02/2017 15:33:03

Steve, I think Graeme is right about Balsarite, but I also think it was withdrawn from sale in many states as there were fears that some of the ingredients were carcinogenic. I believe that although it may be available again in some states, it is a "watered down" version.

They are a bit touchy about these things across the pond, but personally, as long as its used in a well-ventilated area (as recommended!), I don't see a problem....

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Pete

Thread: Storm Doris
26/02/2017 09:34:32

Some years ago, I was sent to Belfast by the company I worked for. I was warned that Aldergrove was notorious for its bumpy approach, and sure enough, it felt like a roller coaster ride!

The thing finally slammed hard onto the runway, following a couple of big bounces, at which point the pilot engaged full reverse thrust.

The (very nervous) passenger alongside me mistook this for throttling up! "Oh, God!", he moaned, "They're going to make him do it again until he gets it right!!!"

surprise

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Pete

Thread: Starting a motor for the first time
26/02/2017 09:26:20

Manny: Glad you got it sorted! laugh

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Pete

24/02/2017 19:06:39

Manny, I'm not that up on Enya plugs, but IIRC, their numbers go in the opposite direction to OS for the heat range. Talk to any of the helicopter guys still running IC engines, and you will find nearly all of them running OS 8s. You don't want the engine stopping unexpectedly in a heli.....! wink

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Pete

24/02/2017 18:52:11

Manny, that engine sounds pretty close to correct - you are not far out! Its difficult to tell from the video, but it sounds as if, when throttled back hard, it slows down and then picks up slightly. If so, then the idle needle is probably slightly lean.

I know this sounds counter-intuitive, but if it is slightly lean at tickover, suddenly opening the throttle will flood the chamber with rich mixture and cause it to bog down for a while. Try richening it a fraction (say 1/8 of a turn at a time). You may need to speed the tickover up slightly when you've done this, as it will slow the tickover!

One other question, what plug are you running? This can make a BIG difference! I only use OS No.8 plugs these days, unless my engine needs a long reach plug (I have some oldies!), in which case I use one of my dwindling stock of Super-Tigre plugs. I would strongly recommend an OS 8 - or possibly an Enya 5.

If you throttle back hard, leave it shut, and it continually slows down, its too rich at tickover. If it slows down and picks up slightly, its too lean.

You are very close. Easily within quarter of a turn, I would say.

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Pete

Thread: Sharkface
24/02/2017 15:30:39

OK, David, but where's the bit that goes across the bottom? Or did yours wear false-teeth for that bit? wink

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Pete

Thread: More Re-visited RCM&E Designs
18/02/2017 11:15:37
What a out the Sub-Mini - a half sized Super 60? I think it was January 1965. I still have two, one with single channel, the other two channel ruddr and elevator. Great little models for .049 class motors.
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Pete
Thread: Any Idea What This Is?
13/02/2017 09:29:15

Another vote for the Sandpiper. The Skydancer was very similar, but was a tail-dragger. I think they both used the same wing.

I had a Skydancer back in the day, and it was a delightful little aeroplane. I have an untouched kit awaiting its turn on the building board......

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Pete

Thread: Are the BMFA Mandatory Questions Applicable?
11/02/2017 16:47:03

The chap currently in charge of the achievement scheme is someone I know. He is a very reasonable sort, and open to *constructive* criticism.

My problem is that the nearest of these meetings would involve me in a 280 mile round trip - not something to be undertaken lightly, and I don't think I could justify the expense!

An old friend of mine (and flying buddy of over 50 years, now!) has been an area chief examiner for over 30 years. The last time I spoke to him, he was seriously talking about packing it all in. Why? Because he is now expected to know the ins and outs of many different disciplines within the hobby in some detail. Like he says - life is too short!

I support the Achievement Scheme in principle, but I believe it has become too complex and unwieldy for its own good. Too much emphasis seems to be placed on being able to quote - parrot fashion - chapter and verse, rather than to demonstrate any real understanding. And far too often, it is being used for purposes for which it was never intended.

Perhaps time for a major re-think?

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Pete

08/02/2017 17:23:50
Posted by john stones 1 on 08/02/2017 16:00:00:

Get yourself elected Peter if you wanna change things teeth 2

John

Been there, done that! wink

I actually had this argument at a full council meeting a few years back, and watching the then Tech Sec trying to square the circle had the rest of the Council gasping in disbelief! I was under the impression at the time, that it was something that was going to be looked at in more detail, but it seems to - once again - have fallen off the agenda!

(Sorry! This one is a bit of a hobby horse of mine!)

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Pete

08/02/2017 15:56:07

Well, said, Piers. My sentiments exactly! Surely all that is required is that a pilot should be aware of his obligations under the law, not to be able to quote chapter and verse. We are not trying to pass the Bar exams!

One of my problems with the achievement scheme - which I support in principle - is that it has suffered from serious "mission creep" over the years. And this has not been helped by the BMFA's own attitude to it, saying on the one hand that it is only for personal satisfaction, and should not be used as a certificate of competence, and then using it as a prerequisite to enter the Nationals!

It does seem to have taken on a life of its own!

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Pete

Thread: Charging a Lithium Iron Motorcycle battery
08/02/2017 15:45:34

I don't know about bikes, but I used to race karts (Villiers 9E4s, highly modified!) back in the day. We stripped all the standard ignition systems off them, and ran them off a 12V lead/acid, with NO charging circuit. The batteries were charged off the kart prior to race week-end.

Most on-vehicle charging circuits are pretty crude, and although the nominal voltages match up between a 4-cell LiFe, and a 6 cell lead/acid, I don't think I'd want to risk an expensive LiFe battery on a vehicle's internal charger.

In other words, its not the using of the battery on a road bike that is the issue, but whether the on-vehicle charger is suitable for it.

Your model charger should be absolutely fine, if set as Phil suggests.

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Pete

Thread: Flying over the Devon hills
06/02/2017 08:36:43

Glorious Cliff! I would have been up there myself, but for other commitments. Curses, foiled again!

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Pete

Thread: BMFA Nationals notice
03/02/2017 11:54:16

Excellent news!

I had feared the worst, and that we had lost Barkston for good!

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Pete

Thread: Hello all. Cambria Piper Tri-Pacer
03/02/2017 09:15:06

Always had a soft spot for the Tri-Pacer and its relatives, mainly because I learned to fly full-size on one, back in the 60's:

Actually, that was a Piper Colt, a stripped down Tri-Pacer for training. The club had two of them (G-ARNJ and G-ARNK), and also two Carribeans, a de-luxe Tri-Pacer with all mod cons. Both Colts are still flying, but one has been converted to tail-dragger configuration.

Around that time, I'd also just started flying multi-channel R/C, with a Super 60 and six channel "reeds" (rudder, elevator and throttle). The Colt flew just like the Super 60.......! wink

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Pete

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