Resurrecting A Classic Matador.....

[Chris Bott - Moderator]

Hi Mike, that's all very encouraging for my Matty build, maybe I'll find time to crack on with it soon, thanks.

It looks like you'll have many pleasant flights with it from now on. Let us know how the motor holds up. I think the best course of action is to keep flying it as it is, but have the brushless gear ready in case the motor gives up. If you do have that much left in the pack after 3.5 mins then it indicates that current is actually quite low.

One thing I think worth mentioning is that you are using Tamya connectors. Now I have had problems with these and gave up on them years ago. So I thought it fair to at least tell you what happened to me. I used them with geared brushed SP400's at a current of around 10A. All worked fine, mostly. Now and again I noticed they were a bit warm when I unplugged them, but not often. This was on multiple models so not just one set of connectors. I had two major faults with them.

1. I had a speed controller fail into short circuit, the model ended up on the ground with the prop stalled but not far away, magic smoke started to come out from somewhere so I dashed over to unplug and just couldn't. The pins seemed to be welded together and the plug would not come out.. you can imagine the rest... that ruined the motor, the battery, the model and my day.

2. I had a connector fail in the air. The motor stopped I lost radio contact and watched the model spiral into the ground. On inspection, the Tamya connector was still plugged in, but was brown and a little melted one side. A sure sign of overheating in normal use. The overheating had caused the connection to fail...

A change to decent gold plated connectors has served me very well indeed since. It's even possible that you were losing some of your power in the Tamya's at some point.

[Steve Hargreaves - Moderator]

Chris makes a good point.....the Tamiya connector are out of their depth in anything more than RC "toys"......personally I use 3.5mm gold "bunch" connectors...I think I pointed you at some of these in an earlier thread...but I am also quite liking the XT60 connectors too which I use on my boys RC buggies/boats.....be careful though...not all XT60s are created equal....look for "Original" XT60s...the copies are harder to mate/unmate & are prone to melting during soldering.....

[Mike Etheridge 1]

Good point on the connectors, on the flight day one of the club members gave me similar warnings and even suggested he had problems with his batteries in the past discharging with the Tamiya connectors--thanks.

The battery used was the 10 cell 12v pack.

As for Javelin throwing in 1962 I was sent on a 'Surrey Young Athletes Course' by my school to an athletics ground at Motspur Park Surrey. My events were Sprinting and Javelin. Whilst practicing Javelin I was singled out by the coach who pointed out to all the others that my throwing action was perfect, but I would never be a Javelin thrower as I was too short!!!----Good job I was into chucking planes!

Future strategy ---I agree, get some use out of the Geared motor and then intoduce the Brushless motor installation,I need to learn the new technology.

MJE

[Steve Hargreaves - Moderator]

So the 10 cell pack was used....did you use full throttle Mike or did you stick the the mark which says "here & no further" to keep the current under control......I would be really interested in the volts/amps used in this case.....can you not beg borrow or steal a wattmeter from a flying colleague? I think this info would be invaluable....

You might even find that the geared motor will do the job for you......

[Mike Etheridge 1]

Both flight attempts were made using the mark I had made on the transmitter casing. However I was too cautious on the first attempt so the landing you see relates to the first flight,just a trip down the flying field. On the second attempt I pushed the throttle stick slightly further (1 or 2 degrees) until the engine note and associated thrust seemed right,something I think we could all sense.

I will make some enquires about a wattmeter---someone is bound to have one at the club, or perhaps I can obtain one. I must admit there are a few unknowns in this experiment:

---How much power can a brushed/ geared motor produce?--enough obviously to over come the 'no-load' loss and fly a 32 oz plane.

----What is the maximum current that a brushed Speed 400 can take?

-----Is the 18 amp rating of the speed controller a 'coarse' or 'fine' rating?. Modellers at the club suggested they could take up to 10 amps overload---but for how long?

MJE

[Steve Hargreaves - Moderator]

Too many unknowns to draw any useful conclusions Mike.....

A Speed 400 will be fairly happy up to 10A & will take 15A but you will kill it pretty quickly......the brushes arc & burn the commutator & its game over. The "high" voltage from your 10 cell battery will tend to cause more arcing too.....

So if we take say 12A as the safe maximum & probably a voltage around 8.5 ish volts (8 cells) then thats about 100watts......& remember this is input power......a brushed motor is around 50% efficient so probably only 50watts or so to actually fly the plane.....

18A is the max rating......they usually have a "burst" rating of a few amps extra for 30 or 60 seconds or so but the wise aeromodeller will keep his maximum current well under the ESC rating....15A or so maximum I would say. Any component pushed to its limit will fail sooner than one given an easier life..... Also remember thatif you melt the ESC it's likely that the BEC that powers the radio will go with it & the Matty will become a free flight glider......from Bartons Point it might reach the SS Montgomery...& we wouldn't want that......

[Chris Bott - Moderator]

One other thing to bear in mind Mike is that at reduced throttle settings, the ESC is chopping up the DC on, off, on, off very fast. Changing the lenth of the on to off (mark/space) ratio to change the power.

This means that the full 12V is applied through the ESC to the motor during every on period. It these times current will be the same as it would be if you connected the battery straight to the motor, albeit for a pretty short duration. The average current will be controlled by the throttle setting, but the peak could be very high. This in it's self has the potential to kill the ESC.

[Big Bandit]

Hi Mike great video, and I'm really pleased that it fly's . I do however have to agree with Chris, Steve, and your other club members the connectors that you are using are going HR under load. the standard Tamiya are only good for toys as others have said, and the loses compared to gold 2mm or 3.5 mm bullet connectors will be quite noticeable. Change those and keep the brushless setup for an eventual upgrade and you should be on a winner. Good job.

Cheers,

Chris.

[Mike Etheridge 1]

Chris-Big Bandit,

Our club member and my friend Peter Bruce who made the video is a perfectionist and also a very good model flyer. His videos are improving all the time but last weekend with the bright sun he had problems with the viewing screen so he was not entirely happy as some of the flight aspects were missed.

Peter has a background in the electrical industry but also used to fly hang gliders and was one of 11 persons in this country with a licence to fly powered paragliders. As you can imagine he is a very capable slope soarer.

The Tamiya connectors were fitted to a couple of electric Cessna 182's with batteries I bought to fly at The Common Broughton Gifford in Wiltshire where my older brother and his wife had moved to. I would often meet my nephew there and we would re-live old times flying the planes. Prior to buying the Cessnas I bought a Flying Toys B2 bomber to fly on the common. For some reason this black plane used to upset some of the local bird population and they would often chase it around the sky. The last time it flew, once the battery power drained radio control was lost. The plane was at a great height and just flew downwind and landed on the roof of a house belonging to a keen aeromodeller. He rescued the plane the following morning---it has not flown since!

MJE

[Big Bandit]

Mike,

Having just read the previous posts in the thread, I would say from experience 12 Amps is the maximum you should be pulling through the ESC using a Speed 400 motor, and unless you have a fuse in one of the motor leads, you could end up with as Steve suggests a free flight glider. When the comms burn it all fuses together ( you could be looking at 20 amps plus) and closing the throttle doesn't help unless you are very quick, and you will have to be quick to save the ESC. I've got the same motor / gear box that you are using in the shed, along with some 12volt packs of Nims. I'll have play with gold bullets and Tamiya connectors to see what the differences are over the weekend.

Cheers,

Chris.

[Mike Etheridge 1]

OK Chris---I will be interested to hear the results of your experiment as I am sure will Chris and Steve.

Best Wishes,

Mike

[Mike Etheridge 1]

CONCLUSION

Sorry about the delay but I have been given a book as a birthday present yesterday: ‘EMPIRE OF THE CLOUDS’ by James Hamilton –Paterson, I’m half way through it and would suggest all you guys that are interested in British Jet Aircraft should read it as it includes lots of facts that may not have been disclosed in the past.

THE MATADOR

Wing: Designed for ‘free flight’, I would it needs strengthening to support standard radio equipment.

This issue has been suggested with other radio conversions including the Super 60 and Junior 60 to prevent the wings folding when highly stressed. On the Matador I have added spruce spars top and bottom and enhanced ply dihedral braces. The spruce spars I have fitted alongside the original balsa spars.

Covering: Original covering was doped tissue which probably gave better structural support than the current Solarfilm. However the latter enables easy remedies of warps to the structure. Doped nylon would give better structural support all round and may be superior to Solarlex or even Oratex. However the latter I would rate the best covering I have used so far on a model plane despite the cost. It can also be manipulated to exclude structural warps

Tailpane and Fin

Lightweight covering seems preferable as the structure is prone to warps. Permanent fixture of the tailplane and fin to the fuselage would seem to be preferable for a radio controlled model

Fuselage

Original plan probably does not indicate the need to adjust the wing incidence to suit whether the model is intended for free flight or radio control. However this issue is covered by comment only on the Ben Buckle plan and as suggested earlier in the ‘blog’ I found that the wing platform needed to be raised by at least 12mm at the wing trailing edge location.

C of G

For a radio model this should be set to 30% of the wing cord (As recommended by others) which corresponds to the lower spar location. Ben Buckle C of G location is indicated at 33% of the wing cord.

Electric Conversion-Graupner Speed 400 1.5:1 Geared Motor, 8x4 ‘Slimprop’.

This arrangement has only worked with an Ni Mh 12volt battery pack to date with limited transmitter throttle stick movement to limit the speed controller current to its maximum of 18 amps. This current could exceed the maximum current rating for the motor thought to be 15 amps thus limiting the motor life.

The output of the geared motor with this arrangement assuming accurate current readings was

12Volts x 18Amps =216 watts. The Motor ‘no load’ friction/ windage losses were 48 watts,

Therefore the power to fly the plane was 168 watts at 84 watts per pound which would appear to be about right.

The power produced by the motor it was suggested exceeded the normal power by anything up to 100%. However use of smaller battery packs of 8.4 volts and 9.6 volts in practice did not produce enough power to fly the plane.

Brushless Motor

The existing motor set up will be replaced with a brushless motor that produces just under 200 watts with low ‘no-load’ losses.

[Big Bandit]

Hi Mike,

Good conclusion with some valid points raised, in my experience. I have already included some of your suggested changes in my build and will seriously consider others.

As for the book, just read it on the Kindle and it's a great read. I would also suggest Propellerhead by Antony Woodward, and just reading Lancaster:the second world war's greatest bomber, by Leo McKinstry

Cheers,

Chris.

[Mike Etheridge 1]

Chris,

Thanks for the tips on the other books. I finished 'Empire of the Clouds' yesterday, a whole book in two days which is a record for me!

I have not done any aeromodelling for a couple of days but did buy the April RCM&E magazine to keep in touch. Had a call from Peter Bruce who made the Matador video yesterday to see whether I would attend the club's scale event over the weekend. Unfortunately I do not have a scale model to fly and all the family are home so getting out may be tricky, but I could start the brushless motor installation?

Peter informed me that he can see the three masts from the SS Montgomery sticking out of the sea at low tide from his front garden as it overlooks the Thames Estuary. We both agreed it was not vulnerable to the Matador becoming a 'free flighter'as was suggested in the forum, but if the ship did blow up he would keep his front door closed for protection from any Sunami created!. I have spotted the ship twice in the past on sea fishing trips from Sheerness harbour.

Regards,

Mike

[Steve Hargreaves - Moderator]

I can also recommend Propellorhead too....finished it a few weeks ago....very readable. Currently reading Vulcan 607 about the Falklands raid....

The reference to the Matty reaching the Montgomery was very much tongue in cheek.....for those who don't know, the SS Richard Montgomery was a munitions ship sunk off the coast of Sheerness during WWII. The ordanance was never recovered as it was considered too dangerous & as time has gone on the stuff is now considered too unstable to move. I used to work for a company based in Sheerness....Weidmuller Klippon Mike...perhaps you knew them? The guys used to tell me that if the SS Montgomery ever blew it would take half of Sheerness with it.....there are those who think this would be a good thing.....

I believe its a major stumbling block to Boris's idea of a Thames Estuary airport too.....

[Mike Etheridge 1]

Steve,

I have read Vulcan 607 and recently learnt that one of the Vulcan pilots went to the same school as both my brothers. I am not sure they knew each other though?. I think the pilot now flies XH 558? One of my school 6th form class colleagues was a Victor pilot who also flew in Canberras and Nimrods---lucky chap i wonder if he has retired yet, he was working for a Helicopter company when I last I heard from him?

My links with Sheerness are through the Barton's Point MAC only, although my twin brother's wife lived there for a while. She informed me about the species of Scorpion that also lives there!

None of the Barton's Point club members are keen on the idea of the Thames estuary airport as the flying field could be lost if it materialises.

Even though the housing costs are low my wife will not under any circumstances move to the island even if the SS Mongomery blew half of it up!

MJE

Edited By Mike Etheridge 1 on 06/04/2012 14:50:08

[Big Bandit]

Hi Mike, Steve,

I had no idea what was significant about the SS Mongomery and when Mike mentioned the three masts and free flight I immediately thought of interference.

It also brought to mind a mate of mine has had two PZ T28's smacked down close to some mobile masts where he sometimes fly's.

I've never been shot down by the things but I did have one occasion when I parked the bike in a layby near Bedford, I'd stopped there before often in the past. This time when I came to turn off the alarm and immobiliser before carrying on to Old Warden the bike wouldn't start. Then I noticed a new mobile mast close by. I managed to bridge the alarm and disable it then the bike started. After getting home I took the bike to Peak Security who normally serviced the alarm to be told that something had fried the PC board (the solder blobs on the bottom of the PCB were melted into the plastic case) apparently high powered masts can cause problems when the alarm circuit resets automatically after turning the alarm off. That one cost me £400 for a new alarm immobiliser.

As for Vulcan 607, brilliant read, First light by Geoffrey Wellum is another good read and it's on telly tonight after the Battle of Britain on Yesterday.

Cheers,

Chris.

[Mike Etheridge 1]

Here is Nigel's reponse to seing the video of his old Matador:

Hi Mick - looks good remembering how it looked in the bin! I hadn't remembered the original crash prior to the spiral dive so it was interesting reading the article. I've been racking my brain trying to work out when the spiral dive happened and I think it was when I was 16, so it's nearly 33 years since it last flew. Hope you enjoy flying it - nigel

MJE

[Mike Etheridge 1]

As I promised myself if the Matador flew successfully I would improve and complete the cockpit and cabin as shown below. The cabin interior needs a tidy-up though and I am yet to fit the brushless motor.

MJE

[Chris Bott - Moderator]

That's looking great Mike - very well done.

Once the brushless is in, let us know what it weighs if you don't mind?

[Big Bandit]

Hi Mike,

That's looking good, well done.

[Mike Etheridge 1]

Thanks Chris and Chris,

I will dig out my spring balance to weigh the Matador before and after the installation of the brush less motor. I have in mind to reduce the 12 volt battery pack by one cell so that I do not exceed the voltage ratings of either the brush less motor or speed controller. This may have an effect on the C/G so depending on the comparative weights of the brushed and brush less motors and mounting arrangements some ballast may be needed.My guess is that there will not be a lot of difference in the weights of the two motor arrangements?

 

Mike

Edited By Mike Etheridge 1 on 08/05/2012 13:47:25

[Mike Etheridge 1]

Chris,

Current weight of Matador is 2lb 4oz with brushed geared motor and 12 volt battery pack .

I have had no chance to make any further progress due to domestic chores. Gardening may also get in the way of further progress.

Mike

[Mike Etheridge 1]

Chris,

Must try the canopy glue sometime.

I spent about an hour this afternoon creating a ply bulkhead for the brush less motor after removing the geared motor and battery pack from the plane. Everything seems to fit OK without any changes to the cowling. The cowling top just fits without fowling on the bulkhead with the original engine thrust line maintained. I assume with bulkhead brush less mounts they are squared-up, and adjustments for motor side thrust and down thrust are made with washers or similar?

Next step is to glue the bulkhead to the old bearers with both super glue and epoxy glue, and then add the motor and prop assembly. I can then modify the battery pack by removing one cell to achieve 10.8 volts and do the associated electrical including the addition of the Deans connectors. None of this should take too long--I must see how they are getting on at the club with the bad weather as I think another test flight for the Matador could be on the cards by the end of the week after I have bought a 9x4 prop?

 

Mike

 

Edited By Mike Etheridge 1 on 09/05/2012 19:49:59

Edited By Steve Hargreaves - Moderator on 11/05/2012 13:45:16

[Mike Etheridge 1]

I will fit the Deans connectors this afternoon---I have bought 10 pairs so will add them to all other battery packs as necessary.

I have just carried out another test with the 50 amp ammeter in line (No wattmeter purchased yet!) and at low throttle with about 10 amps registering there seems to be enough power to fly the plane. Pushing the throttle further to just under 15 amps gives enough power I think to allow the plane to take off. I have not attempted full throttle as the plane already seems to want to leap off the drawing board where it is secured with two large paint tins! The speed controller is rated at 30 amps so the system is operating within that parameter,but what about the motor---how much current can it take,it has a voltage rating at 11.1V but no current rating is shown?

Mike

Edited By Steve Hargreaves - Moderator on 11/05/2012 13:31:11

Edited By Steve Hargreaves - Moderator on 11/05/2012 13:32:13