Hey Lynn;
Did you notice how smooth it was running? It was MADE as a 2 cylinder engine and balanced as such. Like the 084, out of the box, prop hub and go fly, LOL.
Bob

Today I received the 150 cm two blade composite ground adjustable prop. So an other good reason for test.
Just a reminder, the wood is 150 cm, about 8.5 degree prop, topping the rev at 2850, half power cruising with 100-105 km/h. Takeoff distance 150 m to rotate. climb rate little below 2 m/sec.

So I took the new prop , put it on and for the 2nd try it was matching the figures for the wood prop. So I thougt, ok lets shorten the takeoff distance. I went down to 7 degree pitch which resulted a 3050 static rpm on the ground. I went flying and as expected.
Takeoff distance to rotate shortened about 30 meters, climb rate is over 2m/sec  (2.5m  at 90 km/h)  But cruising power went to 3/4 power with more noise.
To be honest: I did not like that. But its nice to have a prop which could be adjusted to the available runway.

Just for the record. There is one more problem  with higher rpm : hotter engine. The oil was around 80C instead 70C before and cyl head climbed also up to 170 C vs before 150 C. So it may need to add an oil cooler if reducing pitch for better climb and shorter takeoff.

It's not a very good picture, but you can see the "loop" oil cooler on my 2A042. I patterned it after what others on the 2A042/4A084 Yahoo Group had done. Some on those groups who have experience with the military surplus engine maintain that an oil cooler is not an option. I don't know what others used, but mine is a coil of 3/8" O.D. aluminum tubing with 37 degree flare AN fittings. The pic is from last Summer when I test ran the '042, thinking I'd possibly use it for my MiniMAX, but ended up going the 277 Rotax route.

Please don't laugh too hard at my engine test stand, using my old, crusty trailer to hold it in place. It worked

Lynn

There are some news.
I simply love this engine. But I could not resist to make a 1.6:1 redrive.
Result :
Instead of swinging a 150 cm 7 degree  two blader wooden prop direct, topping static rpm on 2850 , cruising 110 km/h on 2750 rpm  with the redrive I took my 160 cm 3 blader carbon from my Hirth 2702 Himax  (40 HP 2.54:1 redrive) and without any adjustment I got 3150  static engine rpm, cruising 2850 on 110km/h .
The two engine by HP is pretty much the same. If I would reduce 1-2 degree, probably it would go 3300 static rpm and it would perform just under a 503.
The takeoff distance is shortened to around 70-80 meters instead of 110-120 with a sluggish initial climb before.
With direct drive I would not take that to shorter runways than 450 meters, now I would do that on 300.
It is a wonderful combo and I dont know why not everybody is flying this way.
Its heavy but its an aircraft engine not a coffeemill.
I love it !!!!!!!!!!!!!!!!!!!

Something more to mention: I called arrowprop to buy their redrive but its not designed for tractor mode, and weight is about 2.5x of the one I designed. Arrow is good on boats, not on aircrafts.

Some new addition.
I have about 1.5 hours flying with the redrive. All above the airport which is 1200 ft long.

Lessons:
1, Vibration exist even on a smooth 4 stroker.  The prop hub driveshaft screw loosen resulted a slight tilt between the two pulleys, which made the belt came off on a circuit. It happened in 2 minutes till it happened. It resulted a dead stick landing on the airport.  
Loctite screw glue and a second nut fixed this problem.

2, Dont overtight the belt.
The edge of the belt is strongly pushed to the edge of the pulley, and started to eat the poliurethan reaching, the steel wires inside. The a steel wire end started to stick out about 2 inches. it was visible but not noticeable by sound, so I landed it on the airport engine idle.

Its still a better option with a redrive, larger prop, than direct from flying characteristic point of view.  But here we go, adding one more part, which can fail and it will fail. Than you get into the question if it is a design flaw or just bad installation.  

I dont get discouraged by this. Yes, the question came into my mind that direct could be simpler and problem free, but learning how much better this engine performs with redrive I still want to stick to the redrive. I can revert within 20 minutes to direct.

Others:
Higher rev does not necessarily mean that you need an oil cooler. The engine is open from the front now, and oil temp dropped very much. So the heat sink at the bottom of the oil sump works very well by itself if airflow is around it. My cowling was almost totally closed.

The startor solenoid failed, its a Skoda Favorit starter, cost USD 50 to replace with 30 min work.

Hi Peter

Good to see you're still enjoying your new engine.

I made my own reduction drives, mainly for the Robin EC44 50 hp 2 stroke, some years ago. Like you, I used the toothed belt system. The reason for this was because the data available showed me the toothed belt was better able to transmit the horsepower for a given width of belt, or number of vee belts. Also that being thinner in section thickness, and not relying on friction, the belt did not get so hot.

But, again like you, after a few hours - and a few inflight failures - I became aware of some of the problems with tooth belt drives.

Firstly, they are a less forgiving belt than vee, or multi vee belts. Because they are effectively a gear drive, there can be no slippage between the belt & the drive pulley. This means the belt does nothing to help even out the sharp drive pulses from the engine - it just transmits them. With vee drives there is the possibility of a small amount of slip that seems to soften the drive characteristics.

Secondly, they are super critical on getting the two shafts exactly parallel. With even the slightest misalignment, the belt migrates to one end, and chews itself up on the guard ring - as you have found!

So in the end I went for the multivee type belt such as these: http://www.fennerprecision.com/capabilities/belts/multi-v-belts.php. They still run a bit hot, but overall seem the better solution to me.

Good luck with your project.

Bruce

Bruce,
I also wanted the poly v but the I came across that there was no aluminium pulley off shelf only iron. And they were heavy like hell.
The other thing is that Raven  http://www.raven-rotor.com/  and many other uses thoothed belts.
Today I fixed the tension problem and its not eating the belt so rapidly, but I could discover that the paralell alignment is really super critical as you say.

I run the engine for 75% power on the ground for 15 minutes and it was OK to take a 20 min flight above the airfield. I investigated again, and it seems I need 1-2 mm spacers under the 6 bracket mounting screws to get the two pulleys paralell. Thats my next step.

I am also in favour of poly V- belt, but I could not find suitable pulleys so far from aluminum.

My first aim was to see how this engine performs better with redrive if it really make sense, or stick to direct drive. I am convinced now that redrive is better, but now I need to enhance the drive system.
So far this experiment costed me USD 100 for the pulleys and belts, USD 120 for the work, USD 25 for the laser cut bracket and 20 bucks for the bearings. So for 270 bucks I can learn a lot about new things

The other thing which comes into consideration is dynamic vibration balancing. I have a Dynavibe balancer and I discovered that slipping belt will make new balacing each and every time the belt slips. And not thoothed belt will slip for sure.
So I am not so convinced yet which way I should go.


Peter

Well toothed belt drives can be made to work - as you say, the Raven guys apparently use them (I couldn't open your link).  Just that they are not as easy or forgiving as poly vee.

One solution may be to get the pulleys machined?  Shouldn't be too difficult to copy the profile off an iron pulley - or even from manufacturer's data - and machine an aluminium set.  In my early days of experimentation I machined tooth belt profiles in a large nylon wheel that the prop mounted on (and it contained the bearings - it rotated around a fixed stationary shaft).

But it may cost you more than $100!

Bruce

Its winter time, I decided to swap the unknown history engine with the overhauled one which sits in my garage. I will repaint the whole aircraft and it will stay with the redrive. Today we have transported it into my friends workshop in a very easy way. Some pics.

The fuselage end of the wing sits on some foams, the spars fixed to each other. The other end is cushioned on the deflated tire, while the whole wing binded together cushioned to the fuselage.
It was 15 min to put this up. The transport took 30 min and its about 20 miles or so, so not for x country trip.

I am seruiosly thinking about some kind of a saddle which sits on the tail and holds up the end of the wings as well as the engine cowling and the other end. That way its even self supported and the aircraft is rolling on its own.

Old engine out today. The overhauled one is "dressing up"-

New steps-  fuselage cleaned and sanded so as the wings.
Goose liver pathe sandwitches served.
A new way of carburettor heat box is created. Its an Y where there is a common axle with 90 degree different ventils from ram air and also from the exhaust. When one closes the other one opens.
I made a new throttle quadrant having the choke, throttle and the carb heat in one.

The wing sprayed today. I selected Mercedes Yellow 1625  the painter sprayed 1626 kinda butter color so both wings will be resprayed. We both happy.
Oh what a fun.

Quoted Text

I am also in favour of poly V- belt, but I could not find suitable pulleys so far from aluminum.

Peter, these guys http://www.aceaviation.co.uk/index_files/Page456.htm might be able to help.

Bruce

Thanks Bruce, they look nice, and it is a good option,  but have to ship the things from India.

Its all painted and coming together back again....

Peter, What is all the stuff on the intake tubes for???

Quoted from Harless Greear

Peter, What is all the stuff on the intake tubes for???

According to my findings when I received the first engine from Bob and tested it around 5....7 degree C , it was building on massive ice.  The carb intake was direct and all the engine was uncovered. It was very difficult to start, and also it could not reach higher rpms, it has rough running.  When I covered the intake tubes with some kind of foams and duct tapes it improved a  lot and also I took some warm air from the cyl heads.

As I bought this aircraft probably the previous owner had the same problem so he also installed foam and duct tapes (see the photos above) still had no carb heat box.

The best solution I find for an esthetic cover of the intake tubes is a foam tube called Aeroflex SSH solar heat pipe insulation. Its made from synthetic rubber, very flexible,  is weather  and UV proof. Its up to 175 C heat and - 40. This is flame retardant and self extinguishing.
Cost USD 10 per metre.

Peter

New engine cranked today with the new carburettor heat solution. It works fine. Its freezing today. I have a throttle quadrant which incorporates the throttle, carbheat and choke.  /I will post some pictures next time/
The vertical and horizontal stabilizer is back and many more little details. New EGT and CHT sensors added, new oil pressure and heat sensors. Everything is doubled, since these sensors will work with my UL instrument developments. Should be back on the airport at the first week of Jauary, and needs at least 1...2 hours run in for the new engine before takeoff.
Next run is to put the windows back and add an additional small petrol tank to enlarge range which is currently about 2 hours 10 minutes.

pkoszegi,

It looks like the redrive positions the prop above the centerline of the plane.  Do you think this will give problems?

My Challenger's prop is well above centerline,  but it is a pusher,  not a tractor design.

Quoted from The Termite

pkoszegi,

It looks like the redrive positions the prop above the centerline of the plane.  Do you think this will give problems?
My Challenger's prop is well above centerline,  but it is a pusher,  not a tractor design.

I have not discovered any in-flight difference with this. The 582 Minimax is also out of center line , we tried downturned and upturned gearboxes, and could not tell the difference but the ground clearance is much better. There we sticked to upturned one.

Peter

Peter, Are you going to cut the piece that goes across the windshield???

Quoted from Harless Greear

Peter, Are you going to cut the piece that goes across the windshield???

I dont understand your question Harless. There is nothing what goes thru the windshield.

In your picture, there is a strip of wood that goes across the windshield from one leading edge to the other, you are supposed to cut that out at the edge of the plywood..

That's one of the few things I called Wayne about when I built my max..

Quoted from Harless Greear

In your picture, there is a strip of wood that goes across the windshield from one leading edge to the other, you are supposed to cut that out at the edge of the plywood..

That's one of the few things I called Wayne about when I built my max..

The windshield is bended over that and srew fixed from outside. I dont see any issue with it, this plane is like this for years.

Some more critical issues like how my wire haired dachsund will fit behind me....

And as I promised a picture of the quadrant I made. Its not a lot of money involved in this project but a lot of time. I dont know if just buying one from Baxter would made my life simpler.  Now throttle, carbheat and choke is at one place.

It looks like the dog has plenty room but he does need a safety harness so he can't interfere with the PIC..

PS: I removed the choke completely and plugged the holes so it could get a little more air, I now use a primer..

Does priming only with out choke fix freezing or even  below freezing flight conditions ?

The Dog will have a harness. Otherwise he licks my ear all the way.

Done, and delivered back to the airport. I have to run in the engine first, than fly. The pushrods of the flaps and the nose cone is still in the paintshop. Probably wednesday. The white registration number is still missing, since I might change the Club, so as changes the number.

Very nice Peter! I'm excited for you! I look forward to a safe flight report.

- Sean

Peter, I don't think using the primer instead of a choke has any effect on carb icing but it does let a little bit more air get to the carb..