Aero120

I fly in in the house and its quite warm in here. But I'll try warming the battery in a pocket and see how it goes. Thanks.

Hi,   I've had an mcx for a couple of weeks and its great. Having an Ic outdoor heli I find it fun and easy to fly and so its not had too many knocks. However the flight time has suddenly dropped to just over a minute before the onboard Led starts to flash and the power reduces. I've replaced the charger batteries and checked the heli to make sure nothing is binding. The recharge time has also dropped so it seems either the battery has lost capacity or the charger is stopping too soon. Has anyone had a similar experience?

Be careful Eric, that could be him!  

Hi,   I think the light visible through the gimbals is the light from the power led that leaks back into the case. I've got the supplied Tx and its still on its original batteries whilst the charger is on its third set if that helps  

So its finally finished and trimmed out; I've changed the colour scheme on the wings and tailplane slightly to aid orientation. My first petrol installation has been quite a learning curve, but its been worth it. Several flights from one tank full mean a trip to the field needs no fuel / starter kit. This is useful in the muddy weather and so is the lack of oil spray on the plane. Its only getting covered in mud, but this easily wipes off with a damp cloth. If I can help anyone else who wants to try a petrol engine I'll answer anyones questions. The best initial advice though is to read and follow the Zenoah instructions. They are well written and as they say based on their practical experience. 

The second issue has been harder to sort. I had an intermittant aileron flutter. It only occured at the flying field and only effected the ailerons. I tried all the usual things, changed the linkages, servos and receiver but it persisted. I then suspected that the problem must be due to the length of the extension from the rear mounted reciever to the servos, giving some 60cm of potential "aeriel" and / or voltage drop to each servo. Having cut 18cmm out of each lead and soldered the lead instead of using a plug, the problem is solved.   Another forum on here "aileron interference" was a great help in sorting this.

I mentioned a couple of issues that I've had with the plane and now I've sorted them I'll mention them here to help if anyone else has a similar experience.   The extra being an aerobatic design is ballance critical. Fingertips just aren't accurate enough. Having set the initial ballance this way, I flew the plane and it was very tail heavy. I made a ballance rig which was far more accurate  this improved things but was fiddley to use. I've subsequently bought a commercial ballancer and can't think why I didn't get one earlier.   This rig is very accurate and can measure down to 5mm movements of the C of G. The plane is now flying well, although I have moved the ignition Lipo forwards so it sits under the fuel tank. This is better as there is now a bigger distance between the ignition and radio circuits.   From trial and error, I have found that 105mm from the wing leading edge at the root is a good ballance point. Oddly enough this is that recommended by the manufacturer but quoted at the wing tip. This might sound obvious but I've realised my plane will never be as nose heavy when fuelled as a "standard" Seagull Extra as my fuel tank is 130mm (its own length) further back in the fuselage. some 20mm of it is actually behind the C of G. Hence the nose down moment of a full tank will be far less than that of a fuel tank in the standard positon. So although the C of G with an empty tank is as per the instrctions, it will never gain as much nose weight when fuelled, but I like the way it handles.

And here's a shot showing just how much muck comes out of the exhaust after an afternoons flying;   It soon wipes off with a damp cloth!

Been a while since the last posting as I've been busy sorting out a couple of issues with the plane. Here's a couple of shots of the completed engine installation  

 Lee, my Club, Bassett Model Flying club is on Google Earth and in use in Warsop Vale. Try Latitude  53°12'39.60"N and Longitude 1°11'25.56"W. Our cars are on the lane and a few planes in the pits around the shed!

Hi, Just a quick update.  I cut the extra length out of the aileron leads, 7 inches on each side and soldered the join in the wire and its cured the problem. The receiver is still in the rear of the fuselage and it all works as it should. I suspect the problem was due to the voltage drop due the length of wire and two sets of plugs. Removing one set of plugs and a length of wire has cured the glitching. I also use JR stuff, a 770 receiver and 591 servos. Maybe its a tad more sensitive to voltage drops than other makes.

Hi, I've been experiencing the same problem on a Seagull Extra that I have recently built. I fitted it with a 20cc petrol engine and put the receiver in the fuselage behind the cockpit to help with  the ballance and to keep it away from the engine ignition system. At home in the house the ailerons were fine, but at the field the ailerons would chatter away and then settle until used. If you got hold of an aileron you could move it a bit by hand. The servos behave as if trying to find a centre point. So I've swapped the reciever, control linkages and finally the servos. All the radio kit was taken out of a plane I had flown so I knew it worked. Did it cure it?, NO! Having found this thread I fitted ferite rings near the servos, still no better. Fitted them at the other end of the wire, no better. So I measured the leads and I had two extension leads totalling 60cm. I 've taken one of the leads out on each side and the servos behave! The receiver is in the middle of the plane now in a more conventional position so I will have to decide if I will mount it there or try a soldered extension lead of about 40cm. I will also have to have a short extension from the receiver so I'm not plugging directly into it.

Hi   http://www.micro-flight.com/   Have a selection of goodies for the mcx. The MD 500 looks very nice. Not sure if there is a Uk dealer yet.

I've just got an MCX and its great, loads of fun flying "Nap Of The Earth" over the furniture and precision landings on dining table place mats having found a route through the light fitting! Slightly more seriously I'm practicing nose in hovers so I can do them with my Sceadu.  

Hi   How about:   PBY 5A CATALINA         for glow / electric   Pitts S1                            for glow / electric ( many S2s available already) Hawker Hunter               EDF hand launched    

Keith, Have a look at the Vulcan to the sky site. Lots of videos including undercarriage tests: http://www.vulcantothesky.org/galleries.asp

Inside the fuselage I repositioned the throttle and rudder servos as far back as I could on a set of bearers.  Worth mentioning here is that the  engine instructions recommend using a throttle mechanism to push against the return spring rather than one that pulls against it. This is to prevent resonance effecting the throttle movement. I chose to use a bowden cable, but so it wouldn't flex under pressure, I reinforced the outer with a thin carbon fibre rod, bound to the outer every few inches with thread and araldite. This works well and allows a small amount of sideways movement at each end to follow the movement of the servo and throttle lever. I did think about using a carbon pushrod but thought it could abrade away on any contact points. Where the servos should have been became home for the fuel tank The Walbro carburettor includes a fuel pump so the tank can be some distance from the engine, so I choose to move it backwards nearer the planes ballance point. I built an obechi frame to hold the tank which is held into the frame with a velcro strap. The tank is the one supplied with the Extra, but fitted with petrol compatible bung, a felt clunk and brass pipes. Tygon rather than silicon tubing is used and I built the breather system visible above based on the information given in the engine instructions. The system has two open vent pipes unlike an enclosed glow system. The pipes loop over the tank and vent out of the bottom of the fuselage to reduce spillage through aerobatic flight.  A trial balance showed that the batteries would have to be in the rear fuselage to avoid the use of any extra weight. I cut a hole in the covering on the rear fuselage and built this frame to hold the batteries and receiver The hole is patched with a peice of white solar film and so can be peeled off when access is needed which won't be very often once the ballance point is established. An advantage of having to move weight rearwards was that it gave me chance to fit this tail wheel that I spotted in a shop. Its a Graupner unit and close to scale for an Extra.

Kelvin,  That looks great, very realistic how it projects through the cowl!

The first step was the mount the engine. Instead of the usual bearers/radial mount, the petrol engine bolts on at the rear of the crankcase. The prefitted captive nuts were removed from the firewall, the front fuel tank mounting removed and the predrilled holes in the firewall were filled. The Firewall was then sanded to remove the grey paint and allow new holes to be marked out and drilled. I chose to remove the alloy mount fitted to the engine as the mounting holes were wider than the firewall, but those on the crankcase weren't. All I had to do was to make a suitable spacer to hold the engine at the required distance from the firewall so the prop driver was in the right place. I chose to make the spacer from dowel and ply Here are the parts cut to size and drilled so that mounting bolts could pass from the back of the firewall through the spacer and into the crankcase. I used bolts from B&Q I think they're roofing bolts with a big flat head and a wider washer to match that would spread the loading into the firwall. Here is the spacer sanded and glued in place. Also note the cutout in the side of the firewall "box" to provide ample room for smooth airflow into the carb fitted with a trumpet. The was made from 3/16 Balsa steamed and curved to fit. And here it all is with the engine in place.On the bottom of the carb is the fuel connection. Initially this was at a forty five degree angle pointing out. Its a plastic moulding over a knurled brass tube pushed into the carb body. The plastic sometimes breaks if you try to move it, however I was lucky and managed to turn the pipe to point rearwards. Also visible is the carbon fibre ninety degree inlet manifold. Relatively expensive, but beautifully made and essential to keep the carb inside the cowl with decent airflow. The ZG20 has electronic ignition rather than the older magneto type found on many engines. At the top of the engine is the crank position Hall sensor that is triggered by a steel stud in the alloy crank extention. The sensor plugs into an ignition unit that will be fitted later and is powered by its own battery.  

Andy, I will and I got plenty of photos to illustrate how it all went together which I will be including.

Simon Yes its still a two stroke with oil in the fuel, but the exhaust is much less messy, partially as you say from the reduced fuel consumption compared to a glow. I can get four ten minute flights from a tank that would only do one such flight with glow. There is also far less oil in the fuel. I'm mixing it at the ratio of 1:30 as a running in mix. Normally this will be 1:40. Glow fuels contain between 10% and 20% oil, which equate to ratios of 1:9 and 1:4. Also I think most of what oil there is burnt so the aircraft doesn't get covered in oil like a glow engined machine. It can be wiped clean with wet paper towels to remove the  mud that is unavoidable at this time of year. The only oily residue is a slight spattering immediately behind the exhaust pipe on the cowl. There are some marks on the underside of the wing and tailplane, but these seem to be more sooty than oily.

The aircraft is built pretty much to the instructions, but as I was hanging a heavier engine up front, I was going to have tyo move as many parts as I could towards the rear of the plane so I didn't have to add any ballast weight. The wings and rear of the fuselarge are built as per the instructions, but I chose to cut away the balsa under the elevator servos and fit a piece of obechi to the rear of the mounts to give the screws something to bite into. I also reinforced the aileron servo mounts the same way. Similarly I changed the aileron and elevator horns to match the rudder. The new horns have a bigger "footprint" on the control surface and so spread the control loads better.

Hi, I've been building glow engined planes and helis since the late 70s and just recently decided to have a go with petrol. I've  searched around asking for advice on the subject so I hope to put together a bit of a guide for anyone wanting to take the plunge. Its worth it for convenience and running costs alone. Plus you get a nice sounding plane that doesn't get covered in oil. As a change to the usual build blog, this plane is now finished and flying. When I was building it I didn't know what would work so with the benefit of hindsight, I can tell you the right things to do. The plane I'm building is the 63" span Seagull Extra 260 fitted with a Zenoah ZG20. This engine is claimed to be an equivalent for 10-20cc glow engines so I can compare it to the Os 91Fx (14.95cc) that I already own. Most obvious is the weight. The Zenoah is 1240g including ancillaries, compared to the 550g of the Os. The bulk of the Zenoah is obvious as is its detailed engineering including the Walbro carb which includes a fuel pump. The economies of scale can be the only reason this engine is nearly the same price as the Os. The Zenoah is slightly more expensive, but this price increases when you include an inginition battery, switch and a 90 degree bend inlet manifold.  To use petrol you also need to buy a compatible fueling pump, fuel tank bung, clunk and non silicon fuel tubing.

Well done Glenn. Looks fabulous. Hope its fun to fly too. You can loop and roll it too as the real one could although it wasn't part of the RTS schedule. Does it do the flat sink at stall speed as per the real one?  XM597 used that manouvre when it did an emergency landing in brazil after the refuelling probe snapped off during a Black Buck Falklands raid.

Thats is very neat and much better than a hatch