Big Bandit Posted May 21, 2012 Share Posted May 21, 2012 Just sprayed it so I'll have a result for when you get back. Chris. Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted May 21, 2012 Author Share Posted May 21, 2012 Thanks Quote Link to comment Share on other sites More sharing options...
Steve Hargreaves - Moderator Posted May 22, 2012 Share Posted May 22, 2012 Great result Chris....looks very good.....I assume the B+W photo is the original Matty from ahem years ago yes? Amazing how little power they need isn't it.....I guess you were trundling around on about 60-70 watts or so.... I have a bit of a theory about the aerodynamics of these model that I've been developing for ooooh! nearly two weeks now & it revolves around the wing section & the type of flying these models did....indulge me for a few minutes if you will.......... Nearly all these Vintage designs are characterised by two things....flat bottomed wings & lots of downthrust....now...when designed they were often free flight models or at best rudder only & were hence designed to fly at two speeds....flat out & gliding. During the motor run they needed to gain altitude as quickly as possible & then during the gliding they needed to assume a nice shallow glide angle to prolong the flight. It is my theory that the flat bottomed section is quite speed sensitive & the lift produced is directly proportional to the speed. Whilst this is true of all aerofoils to some extent I think the flat bottomed section is more prone to larger variations in lift. Hence with the power on it will fly faster & produce much more lift to allow it to climb. In the glide the model flies slower & hence produces less lift thus the nose drops into a nice shallow glide. So far...so self evident but the interesting thing is that now we fit throttles (or ESCs) to our motors & can thus vary the speed. It is during the "acceleration" phase that things get interesting & here the downthrust plays a part......bimbling along we decide to add more power. The power increase is immediate but the model needs time to accelerate. The extra power will now pull the nose downwards until the models speed increases. At the faster speed the combination of more lift & drag will counteract the downthrust & the model will again fly straight. Conversely chopping the throttle at speed will immediately reduce the power but not the speed & the model will tend to zoom climb until the extra speed bleeds away. This phenomenon was very apparent to me recently when flying my Sharkface.....a very small model with heaps of downthrust......it is happy to fly S&L at many speeds but if you whack the throttle open at very low speed you need to be very quick on the elevator to stop it nosediving into the floor.....at least until the speed builds up when you can remove the thumbfull of elevator.... Being a hooligan my Sharky has way more power than it needs & this plus the small size tend to excaserbate the "problem" Quote Link to comment Share on other sites More sharing options...
Big Bandit Posted May 22, 2012 Share Posted May 22, 2012 Hi Steve, I think your right , the mags arrived yesterday and I've been like a big kid flipping through them and telling the missus I had one of those, I knew him, they were rubbish, they had my Elmira for a display model and I never had it back. Until she said you used to have a hair cut like that , retreats to the shed. Chris. Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted May 22, 2012 Author Share Posted May 22, 2012 Thanks Steve. I bet the centre of lift moves back and forth with speed too. No idea if this is true but I know a man who might... I know mine does what I wish though, so won't be changing anything. I am a tad concerned mind you, that the Frog 150 might pull her through the air a bit quick ? BB I do have a pic of me with my first Matty somewhere, not sure it needs posting though purely because of the hair! Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted May 25, 2012 Author Share Posted May 25, 2012 A quick test with some old airfix waterslide transfers soon proved that without any coating on the Solartex, they would just rub straight off again. Using a thin coat of clearcoat seemed to fix that, and the clear background blended too so it was out with the airbrush and Matty got a coat all over. Add some of the decals and out for a quick shot in the garden. The moody shots with the sun through the trees didn't really come off, but you get the idea. (Note to self:- Must complete the front end...) What do we think about a couple of RCM&E stickers on the wings? Quote Link to comment Share on other sites More sharing options...
Big Bandit Posted May 25, 2012 Share Posted May 25, 2012 Hi Chris, It's looking good, interesting about the Clearcoat first. On the old cowl there was some lifting around the edges, so I used some Ponal from the BMFA office applied with a small brush, just where the transfers were lifting and wiped with a damp tissue. It's worked. The RCM&E stickers should look OK on the wings. I'll get mine fuel proofed this weekend, and looking forward to the maiden next weekend weather permitting. Cheers, Chris. Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted May 25, 2012 Author Share Posted May 25, 2012 The transfers are superb BB, I'll be getting some of that paper and spry very soon I think, or at least as soon as I need something else. Juts wondering - what's Ponal? Good luck with the maiden, I hope the wind drops so we can all get some flying in. Quote Link to comment Share on other sites More sharing options...
Big Bandit Posted May 25, 2012 Share Posted May 25, 2012 Hi Chris, Ponal is the stuff the BMFA sell to stick the little education scheme models together with. It's like a very quick set PVA and only comes in very small bottles, it's good for the stick and tissue rubber powered jobs as well. Cheers, Chris. Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted May 25, 2012 Author Share Posted May 25, 2012 Ah OK thanks, I had never heard of it. Quote Link to comment Share on other sites More sharing options...
Big Bandit Posted May 26, 2012 Share Posted May 26, 2012 Posted by Chris Bott - Moderator on 25/05/2012 23:15:09: Good luck with the maiden, I hope the wind drops so we can all get some flying in. I went flying yesterday and was tempted to take the Matty, but it's not fuel proofed yet, and maybe a good thing. My mate who I fly with a lot had a fly away with his Black magic and we'd just maidened that last seen drifting with the motor at full chat towards Croft Hill. Cheers, Chris. Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted May 30, 2012 Author Share Posted May 30, 2012 I made a motor cover topday but am not sure I'm pleased with it yet.. it might be OK when I've covered it in Tex. I just hooked up the single channel Tx that you saw in my first post here. Lo and behold all the planning has paid off and when the Spekky Tx is in trainer mode I have the following controls using the McGregor single channel:- Press once and hold - left rudder Press, let go, press and hold - right rudder Press, let go, press, let go, press and hold - a bit of up elevator. Quick blip - half motor, next quick blip - full motor, next blip - half motor, next blip - motor off. That should make things interesting! I think I'll be glad I'll have a safety pilot who can take over in an instant! Anyone want a go at Greenacres? Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted May 30, 2012 Share Posted May 30, 2012 Lol my head hurts already...... what test do you have to pass for that one then Chris Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted June 7, 2012 Author Share Posted June 7, 2012 There's been progress on the diesel "pod" now Can you spot the difference? Hopefully fears about vibration are now addressed. Who says you can only be a leccy or an I/C flier? Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted June 10, 2012 Author Share Posted June 10, 2012 Something approaching an hour of electric flying with Matty was carried out this morning, and very enjoyable it was too. However, with a reduced prop size she is still overpowered and not a lot of fun to handle flat out. So now, I'm quite concerned about trying a 1.5cc diesel with no throttle. Of course, I decide this just as the diesel pod is almost ready to go... Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted June 10, 2012 Author Share Posted June 10, 2012 Right here's another option. Does anyone recognise this baby DC beauty? It seems to make a nice lot of noise while reliably spinning a 7x4 Yes Geoff, just had it running, so many belated thanks Oh and any idea what the crankshaft thread might be? I'd rather use a standard nut than that long standoff. Quote Link to comment Share on other sites More sharing options...
Mike Etheridge 1 Posted June 10, 2012 Share Posted June 10, 2012 Chris, The DC engine looks like a 0.76 CC Merlin especially if you were able to run it with a 7x4 prop. The larger 'Sabre' would be a bit tricky to start with a small prop. I did have a Merlin as my first engine to power a KK Pirate but eventually lost it in a Southern Junior Models Southern Dragon (September 1962) It it is a Merlin it would appear too small for a Matador which would be better suited to the Sabre. I did dismantle a Sabre a few weeks ago for a friend. The engine was completely seized-up and it was necessary to put it in boiling water to free it up. I have just returned from a holiday in Dartmoor -weather grim! Mike Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted June 10, 2012 Author Share Posted June 10, 2012 Thanks Mike I just tested my electric setup which has a 7x6 prop now. A fresh off charge battery gave 102 Watts at about 8 Amps. But my very light Matty really didn't like that much power. I think I'll be looking for a 7x4 for electric, and of course I have a throttle.. For diesel use though, I really don't want to suck it and see with too much power and no throttle.. Quote Link to comment Share on other sites More sharing options...
Alan Gorham_ Posted June 10, 2012 Share Posted June 10, 2012 Chris The motor is definitely a DC Merlin. For info the prop nut needs to be 3BA. If you are worried about too much power, then you can't ask for a better motor than a diesel to test fly with... Even if you don't try the old trick of test flying with the prop on backwards, you can try a series of powered glides with the motor decompressed and burping, then you can increase comp. at will. Quote Link to comment Share on other sites More sharing options...
Big Bandit Posted June 10, 2012 Share Posted June 10, 2012 Hi Chris, Yep it's a standard Merlin alright, (the super Merlin has a red anodised head, spinner, and crankcase mounted tank. Not enough poke for the Matty. Better to stick with the Frog with the comp screw backed off and a rich run as Alan suggests. Check the "tug" with the leccy setup at home then setup the Frog to a similar pull. At the patch you can always start on the lower settings and lean it out a bit at a time until your happy with it to keep a steady climb. The frog is certainly a better motor to the DC equivalent (DC Sabre) Limit the amount of fuel for the first flights for about 2 minutes, similar to the Tomboy comp with Mills .75 and 1.3 motors. Glide about for a bit and dead stick. Cheers, Chris. Edited By Big Bandit on 10/06/2012 20:59:55 Quote Link to comment Share on other sites More sharing options...
Mike Etheridge 1 Posted June 10, 2012 Share Posted June 10, 2012 Alan, A good strategy,I used to start the Merlin on a 'burp burp' slow setting on the Pirate and after a while in the air the engine would heat up and the revs increase. By this time the plane was usually at a great height and as the revs increased further the plane would 'go bananas' and loop the loop etc -most entertaining. My friends had Mills .75's which were far better and consistent runners. The Merlin did improve with Mercury 8 fuel which even smelt better than the Davies Charlton muck which I first bought in a bottle. KK fuel was also OK! Mike Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted June 10, 2012 Author Share Posted June 10, 2012 Thanks guys I'll have a think about this. I'm not sure I have a moment between now and the fly in to try any of this, we'll see. I'll carry on and finish the pod with the Frog in it, if theres a flying window I'll have a go. Otherwise you might be all "assisting" at the event.. that might cause a giggle or two! Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted June 14, 2012 Author Share Posted June 14, 2012 Progress this evening was supposed to be a test flight with the Frog 150. However she wasn't quite ready and it's very windy still. So instead an engine run was tried in the garden just to check the mount wouldn't vibrate too much (oh - and just for fun ) I have to report that the test was totally successful, it even proved just how much gunge will cover the model and where it will get! I may even switch the model to my DX6i 'cos my hands are still sticky after a couple of washes.. (Can you tell it's been a while since I went all electric? ) So what's left to do? - Strap on a Rx battery somewhere in the engine pod, and set the C/G. Oh and now it's tipping down with rain.. so I think this evening is a write off. Quote Link to comment Share on other sites More sharing options...
Big Bandit Posted June 14, 2012 Share Posted June 14, 2012 Hi Chris, Ahh, but It smells much better than Palmolive hand wash, I recon that the Co op and other UK wide retailers, should sell burnt model diesel fuel, after shave, shower gel, and hand wash . Cheers, Chris. Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted June 14, 2012 Author Share Posted June 14, 2012 - I'm not sure about the smell of burnt diesel, but the whiff just as you open the tin of fresh fuel.. now that's quite something. Was straight from the 70's for me Quote Link to comment Share on other sites More sharing options...
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