No more blogging 'till the New Year

Which leaves me to say have a Merry Christmas and Happy New Year, and thanks for watching this space in 2008.

A great flying day so no engineering.

I took my time preparing stuff this morning, and until very late I was undecided as to which aircraft I was going to take. Finally I chose the Sunbeam and the Yak54. Both flew superbly although starting was a little more difficult probably due to the low air temperature, after all it is winter. At this time of year I tend to use fuel with 5% nitromethane mixed in to help with cold starting.
Met Geoff at the airfield and he brought along his Mustang which was developed from a trip to Cornwall earlier in the year. That's another story.
All in all a lovely day, wall to wall sunshine, and just a light air moving from the North East.


Yak54 in the late afternoon sunshine.

Geoff with his Moki powered Mustang. The tail wheel bracket failed just before this picture was taken, and that curtailed its flying for the rest of the day.

More on the Crankshaft

A day off work, and as the weather forecast is better tomorrow, I'm in the machine shop today.

Finished the front crankshaft part, see pix below:-

I've made a start... To give you an idea of the scale, the 3 jaw chuck is 80mm dia.

A 6mm dia. pin is used to aid setting.

Nearly finished, just the 3.1mm dia. clearance hole and M3 thread to be cut.

Finished and assembled to the centre web with an M3 grub screw.

The hole is clearance size down to the centre and threaded into the 6.0mm hole where the centre web assembly is clamped with an M3 grub screw. Sorry the photo is a bit out of focus, I wanted to get as close as possible to show greater detail.

Flying tomorrow - with a bit of luck!

What did I say?

I was spot on yesterday when I said today the weather would be glorious. Its been wall to wall sunshine and light winds all day - aaargh!

No flying again today...

...but you wait, tomorrow will be glorious when I'm back at work - 'hit happens, aaargh!

So, into the machine shop for some more exciting swarf making. This engine I'm building is my own design, and I'm drawing it up on AutoCad before making the parts. Occasionally I have to go back to the drawing board to make alterations to the drawings because in practice, sometimes things don't quite turn out as you'd expect. Its called research and development or R & D. The engine I've named, the Ketro KT120fst. is 1.2 cu.in., 20cc swept volume and about 22cc full capacity. Its a horizontally opposed twin cylinder four stroke engine also known as a "Boxer".

Centre drilling position for the crank pin.


Having drilled the hole its now ready for reamering.



Finished, and its a good fit.

All the bearings arrived this week, so now I'll be able to finish the diameters on the crankshaft parts, as I will use each bearing as a gauge to test the fit.

All the parts together, nearly finished. Just the counter balance to mill and the holes for the clamping screws.

And yet more engineering

It looks like this is going to be the norm for at least the rest of this month and probably well into December as the weather situation is leaving a lot to be desired. Even the long range forecast doesn't look promising. Anyway it gives me a chance to get on with the Winter project. I'm hoping to have this engine fitted, working and flying early next year. No pix today, (sorry) but I've started on the rear part of the crankshaft. After I'd nearly finished it, it didn't look right so I had to do some cross referencing with the other drawings, and indeed I found an error. Having now corrected the error I can proceed with the part. Luckily nothing was spoiled. The other thing is I've ordered all the bearings for the engine. Six in all, but one size was not available in britain (would you believe it?) so I had to get it from Hong Kong of all places. Then I had to buy ten and I only needed three. Hey ho!
Soon I'll order the cross helical gears for the gearbox. These come in mild steel and will need to be case hardened. The supplier could do that for me but the extra cost makes it more than prohibitive, so I'll do that myself. It was successful on the KT54fs I made earlier, so it should be OK for the KT120fst too.
More on Sunday 30th all being well.

Very bad weather all week-end - NO FLYING...AGAIN!

So more engineering. I've made a start on the crank shaft front part. All the diameters are turned and the M6.0 hole has been tapped. Its now ready for parting off. I'll do that with a hacksaw, and although this sounds a bit crude its my preference in this case as the part protrudes out of the chuck by a long way. Parting in the conventional way would be a bit risky.

Notice the DTI on the cross slide to assist with accuracy.

Turning the 10.0mm dia. Revolving centre for support and helps prevent chatter.

Ready for parting. Note the M6.0 thread has been cut.

Oh! yes, and I've cut the flats on the central web as seen in the log below.

More engineering today

Made the central crank web this afternoon, turned up a piece of mild steel to 29.5mm Ø, drilled a 6.0mm Ø tooling hole in the centre, and parted it off to 3.0mm thickness. Placed it in a 3 jaw chuck mounted vertically on the milling machine, and clocked the tooling hole to centre it on the machine. Drilled and reamered 2 holes through 6.0mm Ø in 'Y' +10.0mm position and 'Y'- 10.0mm position.

Then I cut off two pieces of 6.0mm Ø silver steel to 17mm length, and silver soldered them into the central web. I've not cut the 3.1mm wide flats yet, that'll be done the next time I work on it. Check out the pictures...

No flying today, poor weather conditions

The wind was blowing a hooley today, so I spent the day in the machine shop. Finished the finning on the cylinder heads, and now I'm thinking about the crank shaft design change. I have to enable the use of one piece conrods due to lack of clearance on the lower parts of the cylinders and the pistons. This will necessitate the design change from a one piece shaft to a three piece.

Some pictures as promised

After a bit of household maintenance this morning I managed to get out to the machine shop to do some work on my KT 120fst engine. I've been looking at the Cylinder Block and thinking that it probably won't make as the design is at the moment due to the large size of the big ends. So I'm thinking about making the Crank Shaft in three pieces to enable attachment of one piece Conrods. Anyway, enough of that, today I set up the mill with an angle plate and a fixture to cut the fins in the Cylinder Heads. Take a look at the photos, they can explain far more than I.

Angle plate & fixture mounted on the machine bed

Close up of Starboard Cylinder Head prior to finning

Cylinder & Crank Case with Sleeves fitted

Cylinder & Crank Case with Port Head & two Pistons

1.5mm slitting saw used to create the cooling fins

A late session

Went flying today, though I didn't go until late in the day, had some jobs at home to do first. Arrived at Westonzoyland Airfield at around 16:30hrs. Light winds from the West and glorious sunshine - and there's no-one here. Only brought along the yellow/red Sunbeam and the Pico-Jet. The replacement li-po charger arrived this week, and I'm now about to test it out having had a flight late this afternoon. Oh! yes, and the bearing fell out of the motor again. The Super Tigre engine in the Sunbeam ran well today although it was a bit difficult to start. It seemed I couldn't get enough fuel through by choking so I primed some fuel directly into the carburettor, and then I flooded it, but once it was running it was quite reliable in the air.
As the sun went down the wind dropped and my last flight was dead smooth, even at very low height. Flights like this are rare and are the most satisfying.
I intend to do some work on the engine I'm building tomorrow (Oh! did I not mention that?), so I'll try to include some pictures.
The weather forecast for tomorrow is crap (light rain and sixteen mile an hour winds) and I have to work on Sunday, so that's it for this week as the clocks change early Sunday morning. Winter has arrived.

Early Morning was Best

Yes, the weather took its toll on todays flying. I arrived at the airfield at 09:15hrs and it was dead calm. By 10:00hrs it was getting windy and by 12:00 it was rough. Took both trainers again and flew both and I flew the Pico Jet but there is a problem with the motor, there is excessive "slackness" in the bearings so I only had the one flight. The Super Tigre engine in the trainer is behaving better so I wonder if the problems were related to running in. I'm still a bit disappointed with the power output so I might experiment with some different glow plugs, fuel and propeller combinations. By 12:30hrs I'd had enough, the wind was cutting through me and I could feel my core temperature was beginning to fall so I packed it all back in the car and went home. At least I've had my fix for the week.

A Good Sunday

Probably one of the best flying Sundays this year. The weather has been amazing for Autumn, today starting off foggy but by 11:00hrs the sun burned through and resulted in a hot day. Took both trainers, the Pico Jet and the Yak 54 to Westonzoyland. A lot of pilots turned out to fly although I suspect the early fog put some off. I meant to have covered the slots in the red and white wing this week, but I've been too busy with other things. Thinking on (careful), perhaps I should try covering just the white section. Maybe all the sections are too much - hmmm. Worth a try.
The Yak was a bit unnerving today, my fault, there were a lot of other aircraft flying at the time and I was trying to fly Knife Edge. Got myself in a disoriented state, and near panicked when I wasn't certain which way up the aircraft was after I leveled the wings. Upright - phew! that was close. Time to land, too many other aircraft flying lead me to distraction. Or should that be destruction?.
The Pico Jet performed well, but is a bit lively on the controls and the motor is continuing to resonate at certain revs. Still not sure whats causing it. I'll check the propeller balance and also see if the motor does it without a propeller. With regard to the "lively" bit I think I need a little weight removed from the tail end of the aircraft. I always reckon to do it this way rather than take the easy option and add weight to the nose. I can't remember the last time I added weight to the nose of an aircraft. The need for this change is as a result of the use of Li-po batteries replacing the much heavier Ni-Mh.
The Super Tigre engine in the other Sunbeam is still playing up, I've been experimenting with the carburettor, but with little success. The spray bar position is adjustable, and its important (allegedly) to get it right, and I've found it does make a difference when its adjusted, but it doesn't seem to stop the revs from surging at the top end. I've found to stop it, I need to richen it up a lot but on closing the throttle and opening up again the engine runs extremely rich and needs to be leaned. There is nearly a happy medium I can use but it ain't quite right yet.


Its not likely there will be any mid week flying from now on untill the clocks change again next Spring, although I might be able to get the odd Monday in as shift work and weather allows.

Last of the Summer Flying - Revisited

I lied about the previous entry. Who would have thought the weather would have been some of the finest of the season at this time of the year. Wall to wall sunshine this evening. Last week I was on holiday and it rained every day, sometimes horizontally. This week there's hardly been any rain at all. Just my luck! Never mind, had a few flights with the Sunbeam trainers and I'm not happy with the slots and flaps on the red and white wing, so I'm going to cover them over. Thought I'd try inverted flight, and it was hopeless. Full down elevator required and still the aircraft decended. Those slots have got to go.
Two flights with the Pico Jet and as always good entertainment. Motor is making some strange resonating noises at certain revs. Don't know what this is all about, may need investigating.
19:00hrs., and its too dark to fly. Clocks change soon, Winter's on its way!

Last of the Summer Flying

This is probably the last of the mid week flying sessions. I took the Pico Jet and the two Sunbeam Trainers to Westonzoyland. The weather was a little windy, about 5 mph gusting to around 10 mph, and 95% cloud. Had two good flights with the PJ, and a flight with the 40 powered Sunbeam, and two flights with the 25 powered Sunbeam with the new wing. (Flaperons and slots). This behaves a bit strangely when flaps are deployed, it seems to become a bit unstable. Some more testing and investigating required I think. It got too dark to fly by 19:15hrs., but there was a beautiful sunset, shining scarlet through a break in the cloud. Dam! I forgot the camera.

Sunday 21st September. A bad omen?

Arrived at the airfield at around 10:45, opened the tailgate of my car and my bottle of fizzy pop fell out onto the tarmac and squirted some of its contents everywhere. Was this a sign of things to come? Anyway, got unloaded and took the car to the car park, and walked back to the pits and began assembling the aircraft. First up was the yellow Sunbeam after tuning the engine carburettor after its ultrasonic clean. Once tuned it seemed to be a bit more settled, but was still a bit below par on power. I would have expected 12,500 rpm on a 12 x 7 prop out of this Super Tigre 40, but it was struggling to get 11,000. The flight turned out OK though. The Sunbeam in the picture above has a new wing equipped with slots and flaperons, untested at this time.

Next up, the Pico Jet. I am amazed at the power of this little toy, and the flight length is incredibly long with the 2200mah li-po battery. This is where I discovered I had a problem with the new charger not charging correctly. I seemed to charge cells 2 and 3 OK but didn't charge cell 1 at all. This was confirmed when I tested the battery with a digital multi meter, in fact I found also that cells 2 and 3 were not fully charged. I've emailed the vendor.

Then I thought I'd chance the Yak54. First flight was fine, no problems, but on the second flight the canopy and cockpit decided to part company from the fuselage and ended up like a busted bag of flour on the tarmac. Highly annoying as it was a new one I'd just purchased recently, to replace the one which the same thing happened to in Cornwall back in August. Managed to land the aircraft safely, though. That bottle of pop was trying to tell me something after all!

Wednesday 17th September

The day looked dull all day, in fact it rained during the afternoon, but it soon dried up by 16:00hrs. Arrived at the airfield where fellow members Jim, Paul and Bob had already been flying. My first flight was with the yellow Sunbeam with Super Tigre 40. Having some problems with engine surging at full throttle and richening the mixture cured it although after closing the throttle and opening it again, it went so rich it wouldn't be able to take off. More tweaking improved the problem and I managed a flight.

Next up was the Pico Jet, and Jim said he'd join in with his PJ. So we launched together. I was well chuffed when I beat Jim on top speed and duration. These Li-Po batteries are the bees knees, I can fly my PJ for around 20 minutes and the top speed is phenomenal thanks to a 1700kv out runner motor. Towards the end of the flight I encountered seemingly a minor problem, when I accelerate the motor to full revs the plane drops its nose a lot and after I'd landed I found out why. The motor mount had come unglued and was hanging loose. I couldn't believe the PJ was still in one piece. Lucky!

Back to the Sunbeam Trainer and a bit more tweaking, and some more flying. Its still not right so I'm going to dismantle the carburettor and place it in an ultrasonic bath with some ethanol. Watch this space...

CAP 21 Crash!

Sunday 31st August.
Flying at Westonzoyland as usual, and had a bit of an accident with the CAP 21. The intention was to half roll to inverted, then half loop, but it got as far as the half roll, and kept on rolling, throttle wide open, vertically into the bean field. Oh! sh!t. Walked over to the spot and with the aid of a pair of walkie talkies and a fellow club member who spotted the point of impact. I walked straight to it, and sure enough it was in bits. I had to dig the engine out of the ground, and after further examination, I discovered it was fine, not a mark on it. Its rare you find anything wrong which could indicate a fault in these cases and this was no exception. The radio was working perfectly. I sent off all the radio gear to Horizon and they very quickly found a fault in the transmitter. The RF output was low, so they changed the RF board. Now I find I have 60+ paces of range compared with 32 previously. But I'm not going to take any chances, so I'll only fly aircraft I can afford to lose for the time being.

Sat 13th September, Westonzoyland.

Fine weather today, sunshine and light winds from the WNW. Flew the Pico Jet now fitted with uprated out runner motor, ESC and li-po. Superb performance, even vertical. In the IC section, I flew the Sunbeam trainer with a Super Tigre 40 engine swinging a 9x6 APC prop. Yes, I know its a bit small, and I've ordered a 10x6 and a 10x7 Master Airscrew. Should be here in time for my four day weekend. The engine is about 20 years old and never been used, so its "running in" rich settings for the time being. One thing I noticed is how noisy it is. I guess it was made before the surge to reduce engine noise.

Sunday 27/7/08.

Probably the best day of the year so far for weather and flying. My 2.4Ghz receivers returned from Horizon earlier this week and I've fitted one in the Sunbeam, and one in the Yak54. Flew both today, and no problems - excellent.

Off to Cornwall next weekend, so I must get the other 2.4Ghz receiver fitted in the CAP21 before then. Also I'm still waiting for some Li-po batteries, a charger,motor and an ESC to arrive hopefully this week, so I can fly the Pico Jet.

Flying Now

Current models are Sunbeam trainer, I've had this model for years, Its nearly been shot down twice by someone else switching on their transmitter on the same frequency, but I somehow managed to maintain control and land safely. So now I've finally invested in 2.4Ghz. Powered by an Irvine 25 and guided by Spektrum DX7. My Yak 54 is a fairly new model, laser sculpted by Seagull Models, its powered by an SC108 which is more than ample for vertical performance. Guidance is by Spektrum DX7 with 6 servos. I've experienced a few problems with this engine with regard to keeping an exhaust muffler on it. It just will not stay on, so I've wired it on just in case. Oh yes, the carburrettor has a design fault. There is a reducing sleeve in the barrel which at the fully open position will engage with the body casting jamming the throttle wide open during flight. Spending 30 minutes flying around at full bore is no fun, and landing dead stick with this aircraft is difficult. It does'nt glide far and if you need to turn it drops like a stone due to the tapered wing.

The CAP 21 is 60" span aerobatic aircraft for a .40 two stroke to .60 four stroke engine. I used to fly this with an OS .61 four stroke, but it was 'orrible. It kept changing its trim settings during flight and landings were less than graceful. Currently its fitted with a four stroke engine I designed and manufactured myself, the Ketro KT .54fs. A change of radio to Spektrum with digital servos has eliminated the trim change problem, and the engine has performed faultlessly for over a year. I'm well pleased.


The Pico Jet is a small electric delta. I use 8 x Kan 1050 cells to power the 400 size motor and pusher prop. Guidance is by Spektrum using the AR6100 receiver.