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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: GloFuel
16/02/2008 15:06:00

I have a number of "vintage" helicopters which require the use of straight fuel. Even 5% nitro is enough to cause severe engine running issues!

 I've always used "Bekra" fuels from Model technics, which are synthetic based. I use the 16% for my competition machines and straight (yes it is available!) for my older machines.

Although Bekra is marketed  as a heli fuel, its fine for fixed wing. I even use it in my OS20 4-stroke!

Many European engines - particularly Super-Tigres - are intended to run on straight. And even my (relatively modern) GSM 25 only started to run properly when I put it on straight! That last one really surprised me!

 If you can't get Bekra straight from your local model shop, try contacting Model Technics direct!

--

Pete

Thread: The WORST plane you ever had?
19/01/2008 12:06:00

I can't remember what it was called - I won the kit in a club raffle back in the 70's! It was a swept wing, low-winger designed for a 40, and looked a bit like a Super Sabre. It had the most vicious tip-stall I have ever encountered! You could do consecutive flick rolls just by applying the elevator sharply (and not even fully!) in level flight!

One of our experienced club flyers had a go with it and managed three consecutive flicks (before it hit the deck) just by lifting off to quickly! 

 It was great for club spin contests though! In fact thats how it met its end! I had got it up very high, and it was spinning like a top. I decided to go for one more turn before recovery. As a result, I pulled out a little lower than I intended, hauled on the elevator to level out, and it just seemed to vanish before my eyes! Then there was a loud crunch from about 50 yds behind me! (luckily on open moorland!)

Yes, the dreaded snap-roll finally caught me out, and destroyed the model! I can't say I was sorry to see it go. It looked gorgeous, but the handling was lethal!

 --

Pete

Thread: What cars type and model do the aged flyers use to transport their models
08/01/2008 21:59:00

Vauxhall Omega Estate. Its even bigger in the back than my daughters Volvo! I can get a fully rigged Schluter DS-22 (old BIG heli) with ease!

--

Pete

Thread: 2.4 GHz gear
08/01/2008 17:07:00

2.4 GHz is NOT an exclusive model control band. It never had been, and it never will be! It is an ISM band (Industrial, Scientific and Medical) - ie a dustbin, where they put all the things they can't think of anything else to do with! In that sense its the same as 27 MHz and 459 MHz.

 However, mostly its used for wireless networks on computers - which is where the technology for 2.4 GHz RC comes from. Most (but not all) of this equipment is meant to be sensitive to other users, and most of it is used in towns - not out in the sticks, where the bulk of modellers operate.

So there shouldn't be a problem!

35 MHz is exclusively for RC aircraft. 40 MHz is exclusively for surface models. These bands have been allocated to us and we don't share them (well, there are some maritime buoys and flea-powered alarms for the elderly, but they shouldn't concern us).

 2.4 GHz is shared with other users, but most of them are in urban locations and shouldn't cause us any issues.

That is unless someone fits a 2.4 GHz TV camera in a model and tries to control it with a 2.4 GHz RC system. And if he's that dumb, he deserves everything that will be coming to him! (Probably a Darwin Award!)

 --

Pete 

Thread: 35mHz interference poser
14/11/2007 14:47:00

Putting my engineer's hat on for a moment, we really shouldn't be using single conversion receivers on 35 MHz! The image rejection simply isn't good enough!

Most of the time we "get away with it" because the "image band" (usually 910 KHz below the transmitter frequency, but if the receiver uses high side injection, it would be 910 KHz above) has little or nothing on it! However, there will always be the odd instance where there is something in the image band that will cause an issue, and this is the problem that double conversion receivers address.

The difference between ch 67 and 73 is 60 KHz. I'm guessing that there is a transmitter somewhere in the image band that is overloading the front end of your receiver, and producing an IF of 390 or 510 KHz. This then mixes with the 60 KHz difference signal producing something close to 455 KHz, which is, of course, your receiver's natural IF frequency.

Just a guess, but it is something I have come across before!

Cheers,

--

Pete

12/11/2007 09:22:00

I've only just stumbled across this thread - sorry for the late arrival!

One vital piece of missing information here is what kind of receiver are you using - double or single conversion?

The image rejection properties of a single conversion receiver at 35 MHz are pretty abysmal - about -6dB at best! 

Its quite possible that there is a strong (and legal) signal sitting in the image band, that is mixing with the "interfering"  ch67 signal and producing a difference signal that falls inside the 455KHz pass band of the IF strip.

I seem to recall that there was a similar problem some years back when our 35 MHz band got expanded. The right combination of channels (it needed 3 transmitters) could produce an interfering signal within the front end of the receiver, if the third order intercept point wasn't high enough!

Just a thought!

--

Pete

Thread: Super Tigre 40
08/11/2007 07:52:00

Oh, yes! I know him well!

 Seriously though, I doubt if it is a motor problem - it does sound like a weird fuel feed issue. However, Mick doesn't charge for labour on repairs, only parts. And from the sounds of it, your motor is under warranty anyway!

He will usually get a motor back in the post the same day that it arrives, so if you send it off at the begining of the week, you should have it back in plenty of time for the next week-end.

I think Mick's son Dave is teaching his son to fly with an ST40 equipped Taxi, so there is plenty of "local knowledge" about this application to be had!

 Best of luck!

--

Pete

07/11/2007 19:58:00

Yes, that should be fine.

 I prefer fully synthetic myself - I use Bekra Straight - as it doesn't bake on to the engines like fuels with castor in them, but it ought to run fine on Dynaglo.

 Send it back to Mick Wilshere. He's very good on repairs, despite the gruff manner on the 'phone!

;-)

 --

Pete

07/11/2007 08:29:00

Diamond Geezer,

 What fuel are you running? Remember, STs only like straight - they shouldn't be run on nitro, or you will get all sorts of odd issues.

 In addition to STs, I've also got a GSM25 (Chinese?) and an AirSupply 40 (Japanese) that refuse to run properly if they get even a whiff of nitro! Yet both run like turbines on straight!

--

Pete

Thread: 2.4ghz a warning.....
16/10/2007 19:33:00

Alright! And don't say I didn't warn you!

Q: What's the difference between Ginger Baker and a Chiropodist?

A: A Chiropodist bucks up you feet.......!

--

Pete

Thread: Save 2.4 GHz!
10/10/2007 08:26:00

Zut alors!

 

 --

Pete

09/10/2007 21:31:00

Thanks Myron!

I should also point out that as with all these petitions, you will get a confirming e-mail - in French! However, the confirm link is pretty obvious, even if you don't speak the lingo......!

 --

Pete

08/10/2007 21:14:00
The Belgian Authorities are trying to ban the use of 2.4 GHz without warning, having only approved it a short while ago!

If they get away with this, who will be next?

Full details and a petition are at http://www.save24ghz.eu/

The site is in Dutch, English and French.

Remember, we're all EU citizens now! The Belgian modellers need our support!

If this ban succeeds, it may give out lot ideas.......!

--
Pete
Thread: 2.4ghz a warning.....
04/10/2007 22:46:00

Wait 'till I start on the Ginger Baker jokes........

 --

Pete

04/10/2007 08:28:00

Myron,

What's this I keep hearing about Queen re-forming?

Apparently they are going to call themselves "Right, Fred's Dead"!

--

Pete

03/10/2007 07:59:00

....and ThunderTiger don't make a 2.4 GHz RC system, which probably explains a lot!

BTW, "cheap" wasn't meant to be necessarily derogatory, but a pukka professional system like that - one that meets all the regs worldwide - would probably cost a couple of grand!

In any event, even if it was "spectrum aware" and able to avoid a frequency in use, I would *still* be very wary of using it alongside a 2.4 GHz RC system. Even if it didn't interfere directly, its transmissions would have the effect of "deafening" the RC receiver. Imagine someone trying to shout a message to you from a hundred yards away, whilst you're stood next to the speakers at a Pink Floyd concert........!

--

Pete

02/10/2007 11:48:00

The non-interference aspect of 2.4 GHz only applies to compliant digital systems. Many camera systems are ANALOG, and do NOT comply with the non-interference spec. Some of them may not even be legal in the UK!

Video takes up an awful lot of bandwidth, and cheap, unfiltered camera systems probably tie-up most of the 2.4 GHz band!  I'm not suprised that your gear didn't work with the camera switched on!

2.4 GHz is an un-licensed band - a "dustbin" frequency, just like 27 MHz and 459 MHz. That is not to say that it cannot produce good results in our application, but it is NOT totally interference proof, and if another system interferes with it, tough! You have no right of redress!

--

Pete 

Thread: Today (Monday) is your last chance...
30/04/2007 08:58:00
.. to register your support for democratic reform of the BMFA!

Get over to www.vote-bmfa.org.uk whilst you still have time!

The site will close at midnight tonight (30th April).

--
Pete Christy
Thread: Only 2 days left..........
28/04/2007 08:13:00
....for you to support democratic reform of the BMFA!

Get over to www.vote-bmfa.org.uk and register now!

--
Pete Christy
Thread: Vote! Use it or lose it!
17/04/2007 21:31:00
Antony,

All you need is your BMFA number. You may be able to contact the office and get this, if it hasn't arrived yet.

The deadline is midnight on the 30th, though it may stay open a little after that whilst my web-master saves the database.

Mike and Antony (and all those others who have voted),

Thank you for your support!

I'm going to need it!

--
Pete
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