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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: Taurus retro aerobatic build
09/04/2020 16:10:37

Here's some tank bay detail on mine:

The hatch is held in place (very securely!) by 3 magnets, two at the back and one at the front, making access a doddle!

The hatch itself is part block, part built up:

I built it square initially, installed the magnets, and then carved it to shape once it could be "installed".

The floor of the tank bay is screwed to bearers for access to the steerable nosewheel linkage:

My nosewheel is bolted to the rear of the firewall (just visible at the front of the tank bay), with the linkage under the floor and out of sight.

I use the rudder servo for the nosewheel too:

(topmost in the frame)

The linkage has a large Z-bend under the tank, which takes the piano-wire pushrod from one side of the fuselage to the other. This provides the necessary springiness to protect the servo, but still provides surprisingly accurate steering control on the ground.




Edited By Peter Christy on 09/04/2020 16:12:14

Thread: Liability of Open Source radios
08/04/2020 11:43:09

Whilst it may (in theory) be possible to increase the power output of any system (even 35 MHz!), the extra output available at 2.4 GHz is trivial.

Going from 100 to 200 mW may sound a lot, but a more accurate way of perceiving it is by the dBm figure. 100mW=20dBm, 200mW=23dBm. The dBm figure is a far more realistic way of imagining the increase.

You will get a similar increase just by replacing the standard antenna (2dB gain) with a "high gain" one (typically 5dB gain - a similar 3dB increase!), without ever having to adjust the Tx at all. And that applies to ANY transmitter, Open Source or not.

All the transmitters I have looked at have a typical output of 60mW. The 2dB gain of the antenna raises this to 100mW erp (Effective Radiated Power). It does this by concentrating the RF output in a specific direction, a bit like a torch bulb being "brightened" by placing a reflector behind it - but only in a specific direction.

The higher the gain of the antenna, the more directional it becomes, so higher gains do not necessarily improve performance in our application.

Note: What I am talking about here is "squishing" the doughnut shaped radiation pattern of a typical RC antenna, ie: making the "dead spot" off the tip deeper and wider.

In practice, yes, increasing the output of the transmitter by either a firmware tweak (not trivial!) or using a higher gain antenna (simple!) does break the regulations.

The likely impact of a 3dB increase in power on other users in a typical model club environment approximates to - er - zero! The likely advantage of such an increase to the user approximates to - er - zero! In the case of high gain antennas, the narrower beam of the signal may well prove detrimental!

Note that I am NOT recommending modifying the RF output of our transmitters. 100mW / 20dBm is more than adequate for our purposes, and increasing it does not do our reputation with the powers-that-be any good, at a time when we need all the friends that we can get!

The only system I know of that actually offers 200 mW is (or was?) Spektrum - which is NOT open source! The US versions do - or certainly did at one time - use 200mW, as permitted by FCC regulations. EU versions are restricted to 100mW, but of course if someone grey imports a US spec set........



Thread: Taurus retro aerobatic build
08/04/2020 08:45:46

My KingPin follows a very similar method of construction for the fuselage. I made the decking over the tank detachable, held in place by magnets, rather than cut a hole in the bulkhead for rank access. This meant I could seal the tank bay from the rest of the fuselage. I've had tanks leak in the past, and soak the radio gear in fuel!

This made it a lot easier to hollow out that bit for tank clearance! In fact, IIRC, I built it up.

I also got the linkage for the steerable nosewheel to go internally, under the floor of the tank bay. The floor is removable for access if required.

I'll see if I can get some pix and put them up later.



Thread: Pink and Purple Super Sixty
08/04/2020 08:37:15
Posted by kevin b on 07/04/2020 19:00:33:
Posted by Peter Christy on 07/04/2020 17:25:21:

I would hesitate to cover a Super 60 in film! Nylon or Solartex (if you can find any) would be much more suitable. I had a nylon covered one for many years. It was only a high-speed argument with a barbed-wire fence that finally destroyed it! blush



Super 60 - High speed ?

Isn't that a contradiction ?

Did the wing come off and it plummeted to the ground (followed by the wing, several minutes later).

This was back in the days of reed equipment (pre-proportional control). Unbeknownst to me, I had an iffy DEAC pack powering the receiver. I lost contact with the model and it started to fly away. When it was a LONG way away, I regained control and managed to shut the throttle. I also applied full rudder and put it in a tight and fast spiral dive. When I guessed it was about 50ft or so up, I applied opposite rudder and full up elevator. It actually pulled out about two or three feet of the ground, doing some considerable speed, and went straight through a barbed wire fence! Not a lot left, though the Merco 35, receiver and servos were completely undamaged!

After replacing all the battery packs (one for the receiver and one for the servos), the radio never gave any further trouble, but it was too late for my poor old Super 60!

Its amazing how fast they can go in a spiral dive! surprise



07/04/2020 17:25:21

I would hesitate to cover a Super 60 in film! Nylon or Solartex (if you can find any) would be much more suitable. I had a nylon covered one for many years. It was only a high-speed argument with a barbed-wire fence that finally destroyed it! blush



Thread: Vertigo
06/04/2020 14:57:41

I remember seeing Frank Van Den Bergh fly the original Vertigo in aerobatics at the nationals in the late 60s. It was the first time I'd ever seen a model *accelerate* vertically upwards!

He didn't win (IIRC!), but he did leave a lasting impression on a teenage me!




Thread: Liability of Open Source radios
06/04/2020 14:53:32

I'm not sure what the difference is between Open Source and proprietary code in this case. I can't think of a single instance being reported where Futaba, Jr or any other manufacturer has been held responsible for an accident involving RC gear.

Hardware failure is a far more likely scenario than software failure, and in the past its proven almost impossible to claim for incurred losses even when a demonstrable hardware failure has occurred. When such cases have occurred, the manufacturer has offered to repair the radio gear (usually FOC), but the loss of the model or any other damages is down to the owner and his/her insurance where appropriate.

One of the beauties of open source is that far many more eyes are examining the code than is the case with proprietary software, and when faults are found, they are usually fixed much more rapidly.



Thread: Cox 0,49 vs PAW 80
06/04/2020 09:26:03

I've got loads of Coxs and a PAW 80. My observations: The PAW is heavier and doesn't have an integral tank, as many Coxs do. It doesn't lose as much power when silenced, and is much quieter either silenced or not. Special piston and liners are available for Coxs with an extra transfer port (like the TeeDee) and no sub-piston induction, which brings the power back to (almost) un-silenced levels.

Although the PAW 80 will swing a bigger prop (7x4), it is much happier on a 6x4 - same as the Cox.

But the real killer is starting! The Cox is MUCH easier to start! My PAW 80 is a little brute to get going! I can be there flipping it for ages, without a pop or a bang from it, and priming it is just asking for a painful back-fire! The tiny size of the prop makes it difficult to use any kind of finger protection, and I have received more (and deeper!) cuts from the PAW than I have ever got from a Cox!

It also flatly refuses to start on D-1000 (so-called "easy start" fuel!). It is much better on D-2000, and even better on D-3000, though that isn't recommended for plain bearing engines. (Any comments on this Jon-Laser?)

The easiest way to start it is with some kind of electric starter, but you need to be VERY careful doing this! Most electric starters are way too powerful, and will bend the conrod (at least) if you flood it!

Its a shame no-one makes an electric starter for small engines (based on a 540 or smaller motor, perhaps?), as this would solve many of the problems.

Don't think I'm anti-diesel - I'm not - at least not in model aeroplanes! (Cars are another matter!) I've got quite a few diesels, AM15s, a KingCat, and several PAW 149s. In contrast to the 80, the PAW 149s are little jewels of engines! Easy to start (as long as you don't use D-1000!), quiet and they throttle extremely well.



Thread: Apps and Overlander
02/04/2020 11:31:54

Couldn't agree more! Why does my local bus company's app (which tells me when the next bus will arrive) need access to my photos, etc?

I believe the latest versions of Android enable you to be much more selective about what apps are able to access, but with 5G on the horizon, now would seem to be a bad time to get a new 'phone!

And its not just apps! nearly every website you visit demands that you "accept" them sharing your data with all their marketing buddies, or accept reduced functionality! Why???

Some do provide a "reject all" option, but then keep asking the question every time you log on!

Come the revolution, these jerks need to be first against the wall!




Thread: Round the Pole but Radio Control!
01/04/2020 19:09:37
Thread: Grass Cutting
01/04/2020 19:05:11

I think its fairly safe to assume that your area's Chief Constable will be a member of the Golf Club!

Or am I just being an old cynic?




Thread: The Gov't, CAA, BMFA & UAV legislation thread
31/03/2020 17:07:19

Where is the Campaign for Plain English when you need them?


Are people actually paid to write this stuff? Send 'em all back to school!



Thread: The penny is finally dropping....
30/03/2020 19:23:31

.... in some areas, at least! I wonder how long before our (and other) governments wake up?




Thread: Charmouth, Spring 2020
26/03/2020 17:23:31

I don't think anyone will be surprised to learn that the Spring Charmouth Heli fly-in has been cancelled.

Newlands Holiday Camp, which hosts the majority of attendees, is offering to move existing Spring bookings to Autumn at no cost.

Stay safe, folks!



Thread: Radio
26/03/2020 16:24:17

I actually had a long discussion about this with an Ofcom official, way back when 2.4GHz had just been legalised.

At the time, they were saying that modules could only be used in transmitters that they had been specifically tested in. ie: If one had been tested in a PCM-9, that didn't mean it was also permitted for use in a PCM-10!

I asked if this meant they were going to ask PC World to certify the WiFi adapters they were selling for laptops in every type of computer they sold that they could be used in? He said he would get back to me!

He actually did, and the answer was that they accepted that type approval held for any suitable transmitter. ie: if it was tested in a PCM-9, yes, it could be used in a PCM-10.

They stated at the time that the "transmitter" was the whole unit - not just the module - as the module was not capable of transmitting unless connected to the main unit.

That being the case, as long as part of the "transmitter" pre-dates the rule change you should be good to go!

Now I am not a lawyer, I'm just re-iterating what I was told by an Ofcom official. And, no, I don't have it in writing. But equally, it is a logical argument. And quite honestly, they will only investigate if a complaint is made. A pretty unlikely occurrence, I would guess!




25/03/2020 16:48:34
Posted by MattyB on 25/03/2020 13:20:30:I would love to understand how T9 justify selling the DJT after all this time. Nothing new that uses the V8 or D8 protocols has had a valid certificate of conformity since the regs changed in Jan 2016, and the grace period for selling old stock was only 1 year... sarcastic

But if your transmitter pre-dates the regulation change (as Paul's PCM9x certainly does) then you have "grandfather" rights and can continue using the older protocols!




Thread: Email for a mac
24/03/2020 11:15:41

I do have a Mac, though I don't use it much - mostly for video editing. But Thunderbird (email client) works absolutely fine with gmail, and is available cross-platform (Windoze, Mac and Linux). This makes it ideal should you ever decide to change platforms at some point.



Thread: Has Your Club Made Any Decisions Regarding The Coronavirus?
24/03/2020 11:11:34

Like most people on here, I will - reluctantly - follow the new rules.

What I cannot understand is why public transport was not closed down a week or so ago. Clearly, places like London Underground, over-crowded buses and trains are going to spread illnesses like this far faster than anything else.

When I was about to retire, a few years back, I joked with the wife that I wanted to buy a place in the middle of nowhere! She is now beginning to understand where I was coming from!

We ended up compromising, and live in an almost rural location - but not quite rural enough to escape Boris' Ban!

The appalling weather over the winter has forced us into semi-isolation since before Christmas. Now the weather has finally broken, it looks like we are going to be stuck at home for another 6 months (at least, I reckon!).





23/03/2020 15:39:19

Frankly, living out here, I'm far more likely to pick something up off the post, Amazon, food deliveries, than I am stood in the middle of a field, miles from anywhere. This thing can live on surfaces outside the body for some time, we're told.

So do you sterilize the post before you open it? Amazon deliveries? Food orders? Where do you draw the line?

In any case, most of the major food delivery companies are presently booked solid until the middle of April, so there is no choice but to visit the local shops, or (Shock! Horror!) the supermarket.

Mixing with "the great unwashed" in such places is far, far more risky, than a couple of hours with a small number of sensible people in an isolated location.

Frankly, I trust the other members of our small group far more than I trust the postman, the baker or the candle-stick-maker. These are people I've known for over 50 years in some cases, and there is mutual trust and respect.

We are all being cautious, and self-isolating at home. Current figures for infection in our area are 16 out of a population of 136,000 in the surrounding area. Of course, the true infection rate will be more than this, but even if it is an order of magnitude in error, it is still a vanishingly small number. This is NOT a big city - even remotely.



23/03/2020 12:44:02

With it looking like there might (finally!) be a break in the weather this week, a few of us have been discussing our options. We are all theoretically in the "at risk" group by virtue of age, but otherwise in good general health.

None of us is worried about being on the field in the presence of others (it is in the middle of nowhere!), but have decided that car sharing is out, as is handing the transmitters around! We will also be keeping a reasonable distance apart, and if anyone has any symptoms at all, they will NOT be coming to the field!

We believe that if we are sensible about this, there is no reason not to enjoy our flying while we can.



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