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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: The Gov't, CAA, BMFA & UAV legislation thread
14/06/2020 18:10:31

The BBC are reporting that Sussex police paid out £55,000, but that they are also facing a claim of £145,000 for legal expenses!




14/06/2020 15:17:22

Richard: Whilst I agree that we all tend to back down a bit too easily when presented with "orders from above", in this instance, I have a feeling that it will go the way of the RC transmitting license. This was finally dropped 1) because by charging for a license, there was an implication that the "powers that be" were then obliged to properly police the CB situation, and 2) it became uneconomic to collect it.

I can see the same situation arising here.

If every model flying site were to appear on NOTAMs and aviation charts, and every site complain whenever an incursion occurred, be it a commercial drone or anything else, the authorities would soon have to either take (possibly expensive) action, or concede that they were unable to police their own regulations.

I predict that within 10 years this registration nonsense will have died a natural death!



Thread: FrSky Neuron rpm readings
14/06/2020 12:57:33

Hi Geoff,

My motors were both Overlanders, and they do publish the number of poles. I have a feeling that the number of poles - which I assume refers to the electromagnets - does not have to be the same as the number of permanent magnets, and that could be why a multiplier is needed. However, I'm far from an expert on brushless electric motors!

If its any help, my DS-22 uses a 14 pole motor and needed a multiplier of 2. My Lark also uses a much smaller 14 pole motor, but doesn't seem to need a multiplier. It has a much higher kV rating, so I'm guessing its to do with the number of poles vs the number of permanent magnets.

5055 usually refers to the can size. The motor in my DS-22 is a 5055/06, 580kV motor. Maybe try the figures I've used (14 poles and X2) and see if that gives a closer reading?

Until someone more knowledgeable comes along, I'm running by guesswork here!



Thread: Dynam hurricane
14/06/2020 12:15:52

Just before the lockdown, I bought a Dynam Waco biplane. I'm singularly unimpressed.

I'm not a huge fan of foamies, but I have a Durafly Komet and Spitfire, and they are excellent. Everything fitted, and they fly well.

With the Waco, not one of the aerodynamic surfaces was true. The fin and rudder were bent like bananas out of the box, the elevators were both twisted, and the upper starboard wing has a pronounced droop, which stops the strengthening spar from locating properly!

I've only flown it a couple of times. Its okay-ish, but certainly not what I would expect for the money! I've had one slightly heavy landing - not enough to cause any damage other than dislodging completely that spar in the upper wing!

I will not be buying anything else from Dynam!



Thread: British Nats in the 60s
14/06/2020 12:05:10

Interestingly, Sheila Scott's Commanche ended up being owned by Max Coote, then the proprietor of RipMax. It was damaged beyond repair following an engine failure shortly after take-off from Elstree, though all the occupants survived un-injured.

What is left is on display in a museum in Scotland somewhere! A sad end to a beautiful aeroplane.

Speaking of Dave Platt, I think that Douglas Dauntless at around 09'37" and again at 10'06" was his. IIRC, he hadn't had chance to test fly it before the Nats. I know it crashed heavily on take-off on its first flight, and I remember seeing him carrying armfuls of matchwood back! Someone had just got the first batch of 5-minute epoxy in the country, and he stayed up all night gluing it back together again! The result is what you see there!

Not a man easily discouraged!



Thread: FrSky Neuron rpm readings
14/06/2020 11:50:16

A bit of background: I've been converting vintage helicopters to electric, and for the last two conversions I've used Neuron escs because of the telemetry they provide.

I had trouble with the esc overheating in my first conversion - A Schluter HueyCobra - which turned out to be caused by the drab olive green camouflage paint absorbing a lot of sunlight! That just had an ordinary speed controller, hence my desire to adopt the Neuron for my next conversions!

My first issue was getting the wrong rpm readings for the motor. I guessed that the esc needed to know the number of poles, but couldn't see where this was adjusted. Chris Bott kindly pointed me in the right direction, and my Lark conversion (Neuron 40S) seems to be giving the right reading once the number of poles was set.

Moving up in size, my Schluter DS-22 did NOT seem to be giving the right readings, despite having the correct pole count set (Neuron 80).

This is important on this machine, as it has an early collective pitch head, and needs to be run at around the right rpm. The head-speed is too low to measure on a conventional tach, so I needed to get reasonably accurate rpm readings from the motor.

The tail rotor has a 3:1 reduction from the motor. This morning, I ran it up in the garden without the rotor-head, set the motor speed to an indicated 3000 rpm and tach'd the tail. It should have read 1000 rpm. It actually read 2000 rpm!

In the telemetry set-up, in addition to the pole count there is a setting for "multiplication factor", which defaults to 1. I set this to 2, and now I get the correct readings!

Can someone please explain what determines if this "multiplication factor" needs to be changed? There must be some reason for it being there, but nothing is mentioned in the (rather skimpy) manual, and I have been unable to find any guidance anywhere!

Why does my DS-22 need it and not my Lark? (admittedly very different motors)

If setting up a system from scratch, how do you know if it is needed or not, other than by guesswork or trial and error?

Surely there must be some kind of logic to work this out!

Over to you guys!



Thread: The Gov't, CAA, BMFA & UAV legislation thread
14/06/2020 11:31:05

I've actually found the repeats on BBC4 more entertaining than the main channel! Same goes for ITV-3!




Thread: British Nats in the 60s
14/06/2020 09:33:03

I was a teenager at the time myself! After 1968, real life intervened for a few years! Getting a job, training, getting married, having kids etc. I'm afraid I missed the Mike Birch years!

Although I never stopped building and flying, it was only much later, when my son was getting interested in competing that I started going back to the Nats!

Thanks for the positive comments, and I'm glad you enjoyed this glimpse of yesteryear!



Thread: Horus RTC battery
14/06/2020 09:26:40

It will be doing the same job as the one in your computer - maintaining the cmos RAM that stores things like the clock & date settings. Remember, any "computer" transmitter needs memory, and more sophisticated ones need to be able to keep the time when the main power is switched off.

Some JR transmitters need them too, notably the 388 (and similar). Also the PCM-10, if memory serves me correctly.

If your computer loses its time settings and any changes you have made in the BIOS, its because the cmos battery is flat. Some computers won't boot when this happens. I have no idea what happens to a FrSky transmitter in this case. My X10 is too new to need one yet, and my Taranis is still going strong after 7 years!

Cmos batteries typically last around 5 years in a computer, I'm not sure why they should fail so soon in a transmitter. I've recently changed one in a JR 388 that was donkey's years old!

Usually, once the Tx is turned on, the cmos battery is redundant. It only takes over when the Tx is powered down. Of course, the Horus family use a software switch to turn them on, and the power for that has to come from somewhere, so maybe if the cmos battery fails, you won't be able to turn it on!

Usually, the cmos battery will be backed up by a capacitor, which will keep things running while you change the battery, but not much longer. My advice would be to change the battery as soon as you get the warning!




Edited By Peter Christy on 14/06/2020 09:27:49

Thread: British Nats in the 60s
13/06/2020 18:56:23

I've finally got round to editing up the 8mm film I shot at the British Nats at Hullavinton, between 1966 and 1968 (may have started in 1965 - its a long time ago!)

I've captioned all the people and models I remember. No doubt you guys will tell me who I've missed or got wrong!


Thread: The Gov't, CAA, BMFA & UAV legislation thread
13/06/2020 15:37:59

I think what it is referring to is the current system, where the BMFA collects the registration fees on behalf of the CAA, and then periodically uploads the details of those who have paid and their qualifications to the CAA.

Basically, it means that the BMFA has become a "one stop shop" for membership + CAA.

Of course, you can still register separately if you choose to do so.



Thread: Diesel vs glow on a .5cc engine
13/06/2020 09:33:51

My own experience from decades of running Cox .049s and PAW 80s (both 0.8cc):

The Cox engine is very easy to start and powerful. It can be silenced, but unless fitted with a special piston and liner (which does away with the sub-piston induction) it will lose a lot of power.

The PAW 80 is quieter, and nearly as powerful. It is quite a bit heavier and vibrates more. It is an utter pig to start! It flatly refuses to run at all on D-1000 (so-called Easy Start fuel!), and is a real finger slicer on D-2000, but once going it runs well!

The silencer appears to have little effect on power, but makes it even more difficult to start!

Glow fuel residue is stickier, but easy to clean off. Although unburnt diesel fuel smells glorious, the exhaust residue stinks to high heaven, and lingers in a car long after the model has been removed. It also lingers on hands and clothes! The residue is thinner than glow, and seeps into every tiny crevice in a model, making it difficult to completely remove.

A diesel powered model does not *need* to be fuel-proofed, but nonetheless, will last a lot longer if thoroughly sealed against oil seepage.

The bigger diesels (PAW 1.49s, for example) are much easier to start and handle than the small ones. Very nice engines, in fact, and throttle remarkably well!

The Mills .75 is a good engine for free-flight and very easy to start, but marginal on power for a r/c model.

Just my thoughts on the subject, for what they are worth!



Thread: Dangerous
12/06/2020 14:06:51

Mike B is probably the best person to answer this, but my guess would be that not all protocols support receiver numbering and/or model match.

It may be difficult to implement on some, but not others. Also it is possible that the multi-protocol module doesn't communicate this information back to OpenTx.

'Fraid I don't know enough about its inner workings, but those would be my guesses.



12/06/2020 10:11:32

If there's enough interest I can probably write something about Ace. My connection to them was only second hand, as Mick dealt with them directly.

Yes, I did a lot of work on the electronics side for Mick. I know he had a reputation for abrasiveness (!), but the people who got on best with him were those who were not intimidated, and gave as good as they got! wink

When you got to know him, you could not ask for a better friend, and I actually owed him quite a lot. Shaun Garrity asked me to write a bit about my work for Mick, and he published it in RCM&E an issue or two back. I stopped the article at about the time we were working on 459 MHz, but if there is enough interest, I'm happy to write more.



12/06/2020 08:27:49

You may remember this version:

Its the single stick version. I use it for fixed-wing aerobatics, and you probably saw me with it a couple of years back when I came up to Watford for that vintage aerobatics competition.

They were actually very advanced for their day. There are eight model memories that you can back up to a PC, it has crossed trims (so no stretching across the face of the Tx on the 2-stick version) and an auto-trim button (re-centres the controls to wherever you are holding the sticks!). You can even adjust the rate at which it re-centers!

8-channels, 8 model memories and 8 mixers! But programming it makes OpenTx look like a doddle in comparison!

As with any system, great flexibility comes at a price - often in the form of more opportunities to mess things up! wink



11/06/2020 22:17:08

If you think trim reverse is a problem, you should have a play with my MicroPro 8000!

(This is my 459MHz version)

Servo reversing is achieved by reversing the endpoints for the channel: ie you need to change one end from 1 to 2 mS and the other end from 2 to 1 (you can also adjust the centre!). If you only adjust one end, you get a "V" curve!

The problem is that you have to remember to reverse the rate switches in a similar manner - otherwise, flicking the reverse switch reverses the direction of the channel!




11/06/2020 19:34:01

Barie: Don't worry! I don't take offence easily, and in discussions like this, I'm always aware that what is written can seem very different from how it would have sounded if spoken! (And I'm not sure I'm as clever as you credit me! I've just been lucky to be in the right place, with the right knowledge, at the right time!)

Martin: Yes, there's the easy way to reverse things and the difficult way! wink I suspect its the difficult way that caused you the problem! However, the difficult way is there for a reason that becomes apparent when you start doing V-tail or elevon mixing and need to reverse one function, but not both, on a specific output!

And if its any consolation, I got caught out the first time I set up an i/c powered helicopter! My college computer tutors always taught me to apply complex maths (such as curves!) as late in the process as possible, to avoid "rounding errors". (Bear in mind that we are talking of the era of IBM mainframes and DEC mini-computers here!) I dutifully applied the throttle curve at the mixing stage.

This had the unfortunate effect of raising the idle speed when I raised the middle of the curve to raise the hovering head-speed. The ensuing "hot start" had me scrabbling to yank the fuel line off with one hand, whilst hanging on to the rotor-head with the other for dear life!

You see the "trim" is applied at the mixing stage, which is why the idle was suddenly very fast! When I applied the curve at the input stage (before the trim was applied!), the problem went away!

It was very obvious, once it was pointed out to me! blush

So, not so clever, after all!



11/06/2020 16:53:53

When talking about radio reliability, what a lot of people overlook is the manufacturing process. For the best part of the last 50 years, bad *designs* have been few and far between. Most were variations (I hesitate to say copies!) of established American designs, and could trace their ancestry back to Don Mathes, Doug Spreng and Frank Hoover (F&M).

However, most were built by relatively small companies - especially in the UK - and the build quality could vary enormously!

Once the Japanese industrial giants entered the market, the game was pretty much up for the small manufacturer. I don't think many people realise how big Futaba (as an example) is! If you have a video recorder, or CD/DVD player, the chances are that many of the fluorescent displays - not to mention many of the internal components - are made by Futaba! And what these industrial giants brought to the party was mass production. Solder flow baths and robotic production could build a thousand boards in the time it would take an individual to make just one. Automated production techniques also made things like poor solder joints history!

Now the tables have turned once again, and the Chinese, with an enormous (and cheap!) workforce are able to mass produce high tech equipment even faster than the Japanese. They also seem to be more flexible and responsive to demand!

They have brought the processes of churning out iPhones and TVs to the model control market!

And don't think the Chinese are just slave labourers. They are very clever! Chinese children were playing with toy helicopters when we were painting ourselves blue and fighting the Romans!

I've been using the FrSky / OpenTx system for around seven years now, and not had any issues. It has proven just as reliable as my JR gear is (still!). As far as this numbering of the receivers goes, every time I have created a new model, the system has automatically attached an unused number to the receiver on binding. Yes, it is possible to over-rule the system, and make it use a number of your choice, but if you do that, you must take responsibility for that choice! It is not easily done by accident! If it were, I would have done it by now...! wink 2

I'm not sure how Martin is ending up with reversed trims! No doubt it is possible, but I think you have to work at it! My own technique for setting up models is to leave as much as possible at default settings, and only change things that I actually *need* to change. Because OpenTx has a reputation (undeserved, in my view) for being tricky to set up, its easy to fall into the trap of over-thinking what you are doing.

It really isn't that hard!




Thread: The Lockdown Restrictions Have Been Relaxed. Who's Been Flying?
09/06/2020 19:00:08

During the lockdown, I've been busy converting old helicopters to electric. Had a good session yesterday (Monday). First up a Micro-Mold Lark Mk2:

That one is pretty much sorted!
Next up, a Schluter DS-22 (circa 1974)
That one needs a bit more work yet. The headspeed is still a bit low.
I have a feeling its the model that was featured in the May 1974 issue of Radio Modeller:
The colour scheme is very similar, and the previous owner to me bought it from Dave Nieman's shop in Wembley. I believe the reviewer was a friend of Dave Nieman's, so it could well be that model, though it has had some upgrades down the years!
Thread: Max Thrust Riot versus Wot4
07/06/2020 14:44:06

I currently have a WOT-4 i/c, powered by an Irvine 46, which is a good sport model. However, I found the Foami-E version very disappointing.

I managed to write off a fuselage on the first flight, due to the instructions giving the wrong CofG position! With the CofG as per instructions, it was constantly trying to dive into the deck, and needed a LOT of up elevator to keep it airborne. In desperately reaching for the trim, I managed to switch the Tx off! Exit fuselage no.1!

The replacement fuselage came with a note explaining that the CofG should be (whatever it was), not what the instructions said!

Once that was sorted, it flew OKay-ish, but was never nice. On the plus side, it was quiet and had a very short take-off run. Perfect for less-than-ideal strips! On the downside, it was seriously unstable in pitch! A gentle climb would quickly increase until action was taken to stop it, as would a gentle dive. The elevator required constant correction to maintain level flight. I put it down to the ridiculously floppy tailplane, which must have been blowing all over the place in the slipstream!

I bought it as a test hack for suspect radio gear. Alas the radio compartment was only big enough for small receivers, so not even fit for that purpose, really.

I suppose it was OK for "stick banging", but that's not my style. I finally wrote it off a few weeks ago when I got momentarily blinded by the sun behind a large, bright cloud! I wasn't sorry to see it go, and most of the electronic bits will live on in other models...



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