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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: Horus RTC battery
17/06/2020 22:37:47

GPS signals contain a very high accuracy time signal, so maybe the "Adjust RTC" option allows it to update automatically from a known source. The standard clocks do drift a bit.

A PC can also do this using a timing signal from the internet, so this would make sense. However, I don't have a GPS unit so I can't confirm.

Your mixed results maybe to poor GPS reception indoors? You probably need a good signal for it to work properly.

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Pete

17/06/2020 17:19:32

Thanks for that, Geoff! It looks a bit fiddly, so an "idiot's guide" is very useful!

I do wonder why manufacturers make consumable items so hard to change! I recently did a JR-388 which doesn't even use a battery holder - it uses a battery with tags welded to it, which is almost impossible to find! I ended up soldering some thick-ish solid copper wire straight to the battery. Worked like a charm, but again, dead fiddly to fit!

And don't even ask about the CNC milling machine where we had to dismantle most of the control unit to get at the board with the RTC battery on it.....!

angry

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Pete

Thread: FrSky Neuron ESC
17/06/2020 12:02:57

Thanks Bob, that's a useful link!

He is mostly talking about quad setups, which I believe are generally low-inertia, high rpm set-ups. My requirement is almost exactly the opposite - very high inertia, low rpm! Nonetheless, some of the descriptions he gives are useful!

I get the impression that not a lot of people are attempting what I'm doing, so perhaps I'm pioneering a bit here! Most of the guidance on electric flight conversions applies to either fixed-wing, or high performance helicopters - both of which are pretty well understood.

Working on vintage stuff (typical headspeeds around 1000 rpm, maybe less) is a whole different ball-game. For example, my Schluter Cobra and DS-22 both use motors for which the recommended speed controller is 80A. However, most of the time they seem to be drawing around 20A on 6S. The little Lark flies on 4S and draws around 17A.

Unlike fixed wing, you can't adjust the "prop size" or gearing. You have to choose the motor to match the application. This is where the Neuron comes in very handy, as all the telemetry gives you a good idea as to how close a match you have achieved.

Actually, on the Lark, I did manage to adjust the gearing slightly, as it has a belt drive for the first stage reduction. The Schluters have an oil filled gearbox, and you cannot vary the ratios.

Just to give you an idea of what I'm playing with:

 
 
I need to make a new rotor shaft for the Schluter! There is a lot of play in the "Jesus bolt" that connects it to the gearbox, and the constant knocking is likely to shear the bolt, hence my caution for the moment!
 
--
Pete
 

Edited By Peter Christy on 17/06/2020 12:10:49

17/06/2020 10:37:27
Posted by Mike Blandford on 14/06/2020 23:37:20:

Some settings to check, I had some interesting results with a 600 kV motor and 3S/4S cells:

What is the current limit?

Increase the "ramp up power", I had to do this to get 3 cells to give full power..

Turn rpm power protection off. This is significant more for low kV motors. The Neuron can decide the motor is too slow (e.g. stalled) so limit the current.

BTW, I reckon the full size pup flew on 40 to 50 watts per pound!

Mike

Edited By Mike Blandford on 14/06/2020 23:38:13

Mike: What is your definition of "low kV"?

I see you mention 600kV. I'm using a 580kV on 6S in a vintage heli ( **LINK**

and I have been struggling to get the desired rpm (Neuron 80). When it stops raining (!), I intend to try your tips, but for future reference I would be interested to know your definition of "low kV".

Similarly the "ramp up power setting". I'm flying a modified Micro-Mold Lark on 4S using a 1300kV motor, and a Neuron 40S. Although its flying nicely, its not as spritely as I might have expected.

These parameters are poorly explained in the manual, and a bit of insight into what they actually do would be much appreciated!

--

Pete

Thread: Leisure or standard car battery for charging lipo's
16/06/2020 18:29:17

Posted by Dickw on 16/06/2020 17:32:19:

I used to use Leisure batteries but got fed up of repalcing them every couple of years.

Interesting! I bought a leisure battery some years ago for this very purpose. It cost a lot more than the equivalent car battery, and didn't last at all well. Thinking I was just unlucky with a one-off, I bought another - which lasted a similarly short length of time!

Nowadays, when I replace a car battery (I tend to keep my cars a long time!), I keep the old one and use it for LiPo charging at the field. Even a knackered car battery usually has enough for a days sport flying!

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Pete

Thread: The Gov't, CAA, BMFA & UAV legislation thread
15/06/2020 09:44:26
Posted by Steve J on 15/06/2020 09:18:30:
The primary driver is enabling commercial unmanned aircraft operations.

Hence my comment about making sure your site is on NOTAMs, etc.

That ought to ensure that commercial drones do not pass through your airspace.

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Pete

Thread: Diesel vs glow on a .5cc engine
15/06/2020 08:29:41

For Cox .049s, special pistons and liners are (intermittently!) available that do away with the sub-piston induction. They also add an extra transfer port (as per the TeeDee) to restore most of the lost power.

These run well with silencers, though I haven't tried to throttle one - yet! wink

--

Pete

Thread: FrSky Neuron ESC
15/06/2020 08:26:05

Some good tips there, Mike! Thanks!

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Pete

14/06/2020 22:12:01

Geoff,

You can calibrate it against your transmitter the same as most other escs.

Set Tx to full throttle (probably best remove the prop first, just in case!), power up the esc. Wait for all the beeps to stop. Shut the throttle. Wait for all the beeps to stop. Disconnect and reconnect the power, and it should now be matched to your Tx.

When you connect it to BLheli32 it should read whatever it is now calibrated to.

--

Pete

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!

**LINK**

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Pete

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!

--

Pete

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!

--

Pete

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!

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Pete

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!

--

Pete

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!

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Pete

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!

devil

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Pete

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!

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Pete

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!

--

Pete

 

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!

Enjoy!

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Pete
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.

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Pete

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