Lancaster

Lancaster – “JoD  Digger”

Background

I can clearly remember the first time I saw the movie “Battle of Britain”. It made such an impression on me so that WW2 propeller aircraft have become things of rare beauty to be appreciated forever, be they Allied or Axis aircraft.

I cannot tell exactly when I had the urge to build a Lancaster, but it has been sitting dormant for a very, very long time, until recently. The advent of good weight to power ratio electric motors with props to suit and the matching batteries have made this dream come true.

Electric Flight magazine recently had an article on a mostly foam constructed Lancaster using direct drive speed 400 motors with Gunther props, which is a low cost and efficient method of propulsion, but not for me. The article continued to describe building methods and of course finally how it flew.

The next day I had contacted Traplet Publications for a plan to be sent soonest possible.

I had also contacted Ramoser Propellers in Germany in connection with their propeller blades with static variable pitch hubs. These come in 2 or 3 or 4 bladed versions and after testing I ordered 4 of the 3 bladed hubs with a swag of various shaped prop blades of different diameters (remember - variable pitch = no worries) After consulting with Knut Neumann (Aeronaut importer). I decided on Speed 300 motors with 6.95:1 gearboxes. These motors should give approx 4500 rpm per volt input power.

Prior to even thinking about building, all testing for final outputs had to be done and of course test equipment built or procured. Final tests done with the motor / gearbox / propeller combination seemed to be acceptable and so on to building – not so easy to produce the canopy and turrets, so back to Traplet and fortunately they have all the “blisters” vacuum formed and available.

As this is quite a time consuming scratch build project, I tried to take enough time to plan and then execute hopefully quickly and efficiently. To this end I shamelessly called on some people and here must thank Max McCullough for his help in foam cutting the fuselage, Morgan Hill for the foam cut wings and Gil Grunberg for the electrics. All are DAC members.

What’s in it?

Wings are high-density white foam, balsa sheeted.

Fuselage is also high-density foam, balsa sheeted, with lite ply strengtheners.

Everything else is balsa bashed including the four engine nacelles, which took 10 hours building time on their own.

Ø      Covering is Litespan and painted with Killrust paint out of the can.
Ø      4 X Aeronaut Speed 300 motors with 6.95:1 gearboxes and variable pitch props.
Ø      8 X RC2400 batteries for power with a 50 amp Schultze speed controller running all four engines.
Ø      1 servo for each aileron, rudder and elevator.
Ø      Landing Gear is home made with the help of Rod King at Hobby and Model Warehouse.
Ø      Total flying weight is 2.3 Kg with approx 1.9m wingspan.

When it came to colour scheme, I really wanted something that had meaning to Australia. Of course the temptation is to reproduce the Dam Buster aircraft. I did not feel that the airframe would take the cutouts for the bomb and leave enough strength, so I then considered the India Squadron colours of 1946. This would have been Black lower surfaces with White upper which would have been a huge weight saving exercise as these are natural colours in Litespan.

As luck would have it I was going to Perth on business and took my camera with me to photograph the Lancaster in the Bull Creek museum, which I had seen before. Once I got there, my mind was made up immediately. I was going to produce “JoD - Bluey and Curly”. Having emigrated approx 11 years ago, I had no experience of Bluey and Curly and had to have an explanation as to what they were, and the spirit of the time.

Settings and Flying

My major concern was the multi engine syndrome of past years. The beauty of electrics really is that all prop/motor combinations can be very close in output tolerances without the problems associated with glow engines. The real added bonus with little on-going settings!!!!!

Initially static tests were done on the 8.3” scale propellers using a pitch of approx 3.5” on all props. I have subsequently repitched to 4” and now to approx 4.5”. This really showed the differences between static and in-flight efficiencies.

I had not put caps on the motors, as I understood that they were already done internally – what a mistake in assumptions!!!! All I can remember of the first flight was a nose pitching down as the aircraft glitched at about double tree height at the Doncaster club, above the billabong next to the golf course. As this happened I immediately came off throttle, which rectified it, and with short power bursts and a fair amount of raging adrenaline, landed safely.

Next flight had the necessary adjustments done to the motors, and with the CG moved back slightly as it had felt nose heavy. Ultimately I have moved the battery pack back nearly 20mm to what I consider to be still scale stable but a pleasure to fly.  I would never have believed that this model would take off like its full size counterpart. As the wheels lift off, the nose tends to point starboard and the backend to port in a wonderful little side slip. I have seen so many videos of their take offs and it is really very lifelike. Climb out is good under full power with me backing off once clear of the trees. If you know the Doncaster Club field, you will understand why! In low wind conditions it will happily cruise at approximately half throttle and give approx 9 to 10 minutes duration.  The twin rudders are really effective and even have the power to taxi easily without steerable gear. In flight it is easy to do very flat turns using rudder and opposite aileron.

The four motors sound great in the air and are really surprising in their efficiency.

Flying this aircraft high and especially with some cloud as background is unbelievable in its reality, especially when slowed to scale speed.

Months and months of work have ended in something that I am extremely proud of. I am grateful that we have access to so much technology today to make all these things possible at comparatively reasonable costs.

There is a saying that all things come to those who wait. In this case it is true and with this experience so many other aircraft are now real possibilities. Think outside the square!

Colin Kahn 

*** 10 January, 2010 10:26 PM +1000 ***

Last updated 10 January, 2010

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