Resurrecting A Classic Matador.....

[Steve Hargreaves - Moderator]

And if it flies we can look at a new battery or a brushless set up.....I like spending your money Mike!!!

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:12:35

[Mike Etheridge 1]

Steve,

Wonderful developments brushless motors---artificial rotating 3 phase stator fields and long life I assume? Li-po batteries excellent, high output but need careful maintenance and potential fire hazards. So far I have resisted them especially as it means an investment of about £200 to ALSO include for the associated charging / balancing equipment. Adding them to the Matador would be like putting an Aston Martin engine in an Austin 7! If I did buy them my wife would be bound to find out!

Somehow I need to acquire / invest in a cheap IC scale model to fly at the club's scale day at Easter. I would need to sneak the plane into the loft at home and somehow accomodate it amongst the 25 other RC planes and control liners.

MJE

 

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:13:41

[Steve Hargreaves - Moderator]

Hi Mike.....brushless DC motors have been around for donkeys years......I think the Blackpool trams use them!!! Where the clever stuff comes in is the sensorless ESC which uses back EMF to establish the relationship between the stator & the rotor.....electronic commutation if you like.....previously this was done by Hall effect sensors.

Where they do score is in efficiency....brushed motors are probably around 50% efficient & wear out very quickly when subjected to the higher currents we put through them in our models.....brushless motors are around 85% efficient, offer more torque & will last pretty much indefinitely provided you don't overload them....

Yes Lipos can be hazardous & there are certainly cases of them bursting into flames.....I would contend that this is more likely down to incorrect usage & charging than any inherent problem with the batteries themselves.....treat 'em properly & you're highly unlikely to have a problem....

But I admire your desire to get the Matty flying with an older set up.....I would probably do the same.........

I think your figure of £200 to get set up is a little high too....for a basic set up for the Matty of around 140watts I think we could get you set up, including a basic charger, for around the £50 mark....

Sorry I'm coming over an an electric zealot aren't I......certainly not the case...I actually prefer IC to power my models but I do find electric flight facinating

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:14:16

[Mike Etheridge 1]

Steve,

OK on the brushless motors but of course they have only been used in the modeling world fairly recently with the electronic 3 phase connections. We do have a German vacuum cleaner (Vorwerk) that we have had for 24 years that has brushless motors, and the study and experimentation of all types of motors formed part of my college course which I commenced in 1965. The vacuum cleaner I assume may well have the same electronics to produce an artificial 3 phase connection to the motors? Certainly the price of the machine was high at £400.

In the industrial world certainly 3 phase motors are cheaper than equivalent single phase motors as they do not need capacitor-start devices. I had one instance on a school extension scheme where there was only a single phase 3 wire 240/480 volt supply available to serve a couple of 3 phase sewage pump motors. We had to specify and obtain static phase converters to produce artificial 3rd phases to run the motors. i imagine the 3 phase connections on the brush-less model motors are produced in a similar manner but with modern electronic technology?

I can't bare to wait any longer to fly the Matador so I am off to Croydon Airport where there might be some other modellers flying today. I will report to you later hopefully with good news?

Regards,

Mike

 

 

 

Edited By Mike Etheridge 1 on 28/02/2012 11:02:10

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:14:50

[Steve Hargreaves - Moderator]

Very true Mike...they are quite new to the world of aeromodelling....

The motors you describe are AC induction motors....very different to our DC brushless motors.....rather than have a rotating magnetic field caused by the sinusoidal AC wave form as in the AC motors the stator coils in a brushless DC motor are constantly switched on & off by the ESC in the right order at the right time to repel & attract the permenant magnets fixed to the rotor part to make it rotate......all at around 8,000 times per second... & in a little unit costing less than a tenner...... Amazingly clever isn't it.....

Wikipedia has a good description....useful if you have trouble sleeping....

Good luck with the maiden.....let us know how it goes won't you.....

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:15:26

[Mike Etheridge 1]

Croydon Airport Aircraft Incident Report..

Oh dear---just as suspected the geared motor had not sufficient guts to take the plane up from hand launches. However on three attempts using two battery packs the plane at least was controllable and is undamaged. As you have suggested (plus others this morning), a brushless motor and lipo battery would seem to be the answer. Alternatively I could dig out the OS 10, but that would mean adding an additional servo of course.

One of the model flyers this morning told me he had built two Matadors and was very successful with them, but agreed he had beefed up both the wing and fuselage structures much the same as I had done.

Looks like I am miles behind with motor theory, thanks for the explanation and perhaps it would be a good time to experiment with the new technology of the brushless motors. It does make me wonder however what sort in plane in the recent past could the Graupner geared motors deal with?

Mike

 

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:15:58

[Steve Hargreaves - Moderator]

So, good news....it flew!!!

More good news.....we can make it fly better.....

Bad news.....you might have to spend some money!!!!

Are you keen on getting it aloft with a more modern electric set up then Mike? If so then might I make a suggestion? I think it would be useful for you to have a scout around the "Electric Flight For Beginners" section of the forum & perhaps a read of some of the tutorials & articles in there....some good work has been done in there & will help with the basics....then perhaps start another thread (a new thread always gets more attention.....the existing threads tend to attract only the old lags already in it....IYKWIM.....). Call the new thread...."Electrifying a Matador" or something & the sparky fliers of the parish will offer their suggestions as to the best way to lighten your wallet.....

Take a look at Lee Damms thread too.....he's building a new Matty powered by electrons for the Vintage fly in....

Alternatively you could fit the OS10 & a 9g servo & fly the Matty as Mercury intended

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:16:37

[Mike Etheridge 1]

Steve,

I suppose you have to go back to the days of the Wright brothers to find out the true definition of flying?That the Matador flew this morning may be an exageration but the other modellers / flyers thought it would have a chance with the right amount of power, and one chap in particular suggested that 'Giant Cod' could provide most of the brushless and lipo battery gear for less than £25. The implication would seem to be that you would need to know precisely what you want from Giant Cod as they appear to be a mail order company?

I have just looked through lee Damms thread and was impressed with both his building photos and approach to the electric power requirements. A new balsa model plane structure looks most impressive and obviously beats repairing an old plane rescued from a dustbin!

A few years ago I did buy books on electric flying at the same time I purchased the Graupner gear from Peagasus Models of Ipswich. Since then I have been spoilt with planes like the Twinstar 2 which has been very reliable to date but has still suffered from battery and speed controller failures and has been re-motored with brushed motors as the originals wore out. Very little brain power was needed to resolve those issues though unlike power needs for the Matador! It would seem with electric power you cannot over-power a model and then just throttle back as with IC models most of which including mine are over powered these days?

MJE

 

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:17:15

[Steve Hargreaves - Moderator]

Hi Mike...just a quick post cos its late.....& I'm off to Germany for two days tomorrow so won't be around....

Giantcod are a great source of all the electric bits you would need & at good prices....as you say they are internet based mail order only so you doo need to know what you want.....but fear not...we can help you.....

 

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:17:56

[Mike Etheridge 1]

Steve,

I found the delivery box that contained all the electrical gear I bought from Galaxy models of Ipswich (Not Peagasus!) it was dated 2003, So presumably brushless motors were not in use at that time for models otherwise Galaxy may have given me different advice and supplied different kit? (Is there a blame culture on this site?)

I have dug out the OS 10, it was priced in a sale in 1976 for about £9.08. I have never used it to date because the Mini-Concord I was building to take it was stolen from a lock up garage. That said they neglected to take the wings! Other modelling items went including my original Southern Dragon box!

If I do use the OS I will have to form a bearer plate as I moved the wood bearers to accomodate the Graupner geared motor that might just make a good food mixer? Alternativey I have an ASP 15 unused that would give plenty of umph and may fit the wood bearers as they are? However if you can advise a suitable brushless motor especially one that might work on my store of 9.6 volt Ni mH batteries I would appreciate it.

I noticed on another site someone suggested that the C/G should be altered on the Matador from 33% cord to 30% cord if radio and an elevator are added. If the plane is for free flight only he advises that the 33% figure should be retained. I will make that adjustment.

Hope your trip went OK?

 

Regards,

 

MJE.

Edited By Mike Etheridge 1 on 01/03/2012 12:27:51

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:18:27

[Mike Etheridge 1]

IC Engine options are photographed--the ASP was fitted some years ago in a Russian (Dementiev-spelling?) F2D (Or E) control line combat plane bought at the Nationals. The ASP engine selection was part of my nephew's and others development of 'Club Combat'. I have only flown the plane once and was never good at control line and who needs induced dizzy spells at my age? However comparing the physical sizes of the ASP and the OS 10 there is surprisingly little difference. The bearer spacings of both the engines is more of less the same. To remove the ASP from the Russian combat plane to fit in the Matador would seem like changing from the sublime to the rediculous. However it seems the best option and all I need is an RC carb from 'Just Engines'. The OS 10 can go in a second hand Veron Mini-Concord which is waiting in the loft for attention.

I think it's a great shame the Graupner geared motor did not work as it fitted perfectly in the Matador, but it was obviously intended for models less than 32 ounces that the Matador weighs as confirmed elsewhere. I will do a volt-drop test at full load on the motor before I remove it just to ensure my 9.6 volt EMF batteries are not the cause of failure. Unfortunately I have not got a suitable wattmeter or DC ammeter to calculate the battery power available at this stage.

It may still be the best option to add a brushless motor rather than an IC engine to the plane the only problem I see is the need to 'bulkhead mount' the motor rather than fixing to the existing bearers.

Edited By Mike Etheridge 1 on 03/03/2012 13:08:12

Edited By Mike Etheridge 1 on 03/03/2012 13:09:28

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:10:22

[Chris Bott - Moderator]

Hi Mike, lot's of options there. I have an Enya 15 and an OS10FP in the garage. But I also have the 1.5cc diesels to try. I'm all electric these days so mine could even end up that way, who knows.

I used to use that very same geared SP400 in electric gliders a good while ago. I always found that with slightly too small or slightly too large a prop they would be pretty useless, but if you happened to find the one that hit the prop size sweet spot, they actually did the job OK. Nothing like a brushless / lipo combination mind you.

I'll be very interested to hear your battery voltage results. There is a good chance that they will be dipping a bit too much under load.

 

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:01:20

[Mike Etheridge 1]

Chris,

Plane battery is on trickle charge at present and I will follow this up with a 'fast charge' befor the volt drop test. I had considered increasing the battery EMF beyond the 9.6 volts by adding more cells or creating a new NimH battery pack with AAA batteries. The trouble is I am not sure what the critical voltage is to prevent damage to the associated receiver, speed controller (although this is voltage rated) etc. On my Twin Star I have other larger cell battery packs one of which has an additional cell creating 10.8 volts which is noticeable in the plane's performance.

As for diesels all my early aeromodelling experience from the age of 12 upwards was with diesels, and my friends and I used to start them as a form of entertainment in our back gardens much the annoyance of various neighbours.We were eventually banned / restriicted by our parents from running them all day!. There were two junk shops in Croydon that sold second hand motors so we had a regular supply of early diesels at very cheap prices. I was sad to see one of the 'junk shop' buildings completely destroyed during the recent riots.

On thing we did with diesels that I doubt anyone does today is to hand test them. By holding the engines in our left hands ,squirting diesel fuel in the exhaust ports and then flipping the props over till the motors started.----we suffered no injuries as the engines soon stopped!.

 

MJE

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:01:46

[Chris Bott - Moderator]

Blimey that hand test does sound a bit dodgy! Although I have vague recollections of trying simalar stunts a very long time ago.
I can just imagine today's fun police coming down on that really hard.
If it's OK with you I'll not try it!

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:02:16

[Mike Etheridge 1]

Chris,

 

The volt drop test on full load / engine speed showed a PD just in excess of 8 volts. The voltage dropped to under 8 volts after about a minute's engine run. I am just wondering whether my last flight test may have been undermined by inadequate battery voltage as I think NI mh batteries lose about 10% of their charge in a short space of time ?---I will look into adding a further cell before I conclude the Matador experiment with the old Graupner gear.

As for hand starting /supporting diesels we started will Mills 0.75's and the more erratic Merlin with 8x4 props, and I eventually started a PAW19D BR combat special in my left hand but nothing larger!!!

MJE

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:02:43

[Chris Bott - Moderator]

I think it's worth mentioning at this point that the starting in your hand technique is highly dangerous and is definately not being recommended. In fact - do not try this at home!

If you were able to measure motor current Mike we'd have a much better idea. It's a shame you don't have the facility. What you could be seeing is a setup with poor batteries and too small a prop, not drawing much current but dragging down the batteries anyway. On the other hand they could be good batteries and a prop that's too big, so it's pulling huge ammounts of current that the batteries are just about supporting, but the large prop is slowing things down too much.

I guess having said that, you might even have the optimum set up for that motor but even then it will still never be enough... Unfortunately we just don't know.

 

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:03:14

[Mike Etheridge 1]

Chris,

Hand starting engines I agree should not be recommended and it's something my friends and I practised when we were younger and less safety aware.

What we learnt with diesels was that it's a good idea to always keep your left hand fingers on the compression screw when starting the engine for continuous adjustment. The comp screw should always be slackened off prior to choking the engine or priming it through the exhaust ports if a silencer is not fitted. If possible never use a tool to turn the engine over as you do not get a true feel of the compression available. If necessary use a 'chicken finger' especially if small props are being used. Gradually increase the compression till the engine fires and then runs. Once running slacken off the compression till a miss fire is heard and then increase the compression to just eliminate the mis-fire. If the revs drop when the engine heats up then further slacken off the compression. It is also necessary to adjust the fuel needle so that the engines reaches it maximum revs before cutting out. This can usually be sensed and once at this point it is necessary to turn the fuel needle back to provide a slightly richer setting---Hopefully this is a more usefull comment on starting diesels? ----I am not good with glow motors!!

Thanks for the response on the Matador electrics. it's a shame nobody has produced BHP / Prop /engine speed/ battery voltage curves for the old geared motors in the same way that IC engine tests have been produced---or have they?

MJE

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:22:10

[Chris Bott - Moderator]

Thanks Mike, yes I think I was getting a feel for things when I was trying the two deisels. My starting finger certainly seems to have retained the muscle memory from my youth. I'll keep your suggestions in mind next time I have a go.

Nope I don't know of any useful data for the old motors myself. There may well be some out there of course.

Chris

 

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:04:07

[Chris Bott - Moderator]

Lots of data here Mike. Possibly too much. Mostly tested on 7 cells. There are three different SP400 motors, (do you know which yours is?) and a few different gearboxes.

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:04:33

[Mike Etheridge 1]

Chris,

The gear box is a 1.5:1 ratio. I am not sure why this ratio was selected at the time on my behalf?

I will have a further look at the data tomorrow but it seems odd that 7 cells were used rather than 8?

 

Mike

 

Edited By Mike Etheridge 1 on 04/03/2012 00:10:07

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:04:57

[Mike Etheridge 1]

Chris,

Having looked at the readings for the 1.5:1 ratio motor it is evident that the props used were significantly smaller than the 8x4 I have currently on the Matador. The 8x4 prop would seem to be the right prop for an IC motor and the Matador. I have always been surprised that the Twin Star with it's very heavy battery pack flies both high and fast on two standard brushed 400 motors and very small props. Perhaps I should try a small prop or two on the Graupner motor especially as the person who produced the data / readings suggests it's not so much the thrust of the motor but the speed of the aircraft that makes it fly?---aeronautical degree needed?

I am still not sure what would determine the selection of one gear ratio from another in terms of prop selection. The suggestion is that they are reduction ratios presumably to reduce current demand for larger props?

I have ordered a 50 amp rated DC ammeter to do a current demand check on the Matador but the delivery time is not good. Nothing in Maplins for sake of argument was available with DC current ratings higher than 10amps.

MJE

 

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:05:30

[Chris Bott - Moderator]

Hi Mike

We always use something like this wattmeter there are plenty of different ones available. They measure volts and current at the same time and also display Watts and mAh used out of the battery. No self respecting electric flier is without one.

As for using a prop smaller that 8x4, that really doesn't ring true with me. I seem to rememeber using 9" or 10" folding props on my gliders. But then mine could well have been the common 7.2V version of the motor, whereas this guy wrote his tables using the 6V and 4.8V motors.

I think we may be going down a route that will still not fly the Matador here. I hope you don't spend too much money going any further this way.

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:05:58

[Mike Etheridge 1]

Chris,

I am familiar with watt meters from my 47 years in the electrical industry and from my College days plus my school days stuying A-level physics. As I was never an installer / tester I never owned any test equipment I just borrowed it from 'the office' and on some occaisions hired computerised monitoring equipment.

Could you provide with the specification / make of your meter please?

Thanks again for your advice on the props as you may have guessed my experience has mainly been limited to 'ready made' electric planes where someone else has done the electric motor /propellor installation design. I may well nip into Avicraft next week and seek their advice on a suitable brush less motor and speed controller. I could fit a ply bulhead mount to the front of the plane to fit a brushless motor which would have to be fully exposed however?

MJE

 

 

 

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:06:35

[Chris Bott - Moderator]

Hi Mike

I use an Eagle Tree data logger, but it's a bit over the top for most people. Click on the image for more info. However it isn't as convenient for measurements on the ground as the one I linked to earlier.

I had to buy the logger and the display separately, and the display can be a nuisance to hang on to while doing measuremets with a prop generating a good draft.
But as well as static, on the ground, measurements I can fit it in the model and record the electrical parameters of a whole flight, then look at a graph using a PC.

 

I also have one that looks like this but it's green. I can't find mine for sale anywhere.
Again, click the photo for more info. One drawback I found with my green one, is that it doesn't hold the max and min readings like some others do. So that could be something you want to look for when buying.

 

 

I think you might find it very useful if you click here and then scroll down to the Electric Flight section. There are lot's of threads there on motor selection, batteries, chargers, etc etc. All really useful stuff.

 

Edited By Chris Bott - Moderator on 04/03/2012 16:21:49

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:07:12

[Mike Etheridge 1]

Chris,

Thanks again for the information. I had no idea such equipment existed and would have to admit it would seem to exceed my requirements, but I am most impressed with the idea of monitoring flight data---a bit different from monitoring the electrical demand of a three-phase supply in a school building etc but similar in principle.

MJE

 

Edited By Steve Hargreaves - Moderator on 14/03/2012 16:07:47