Avro Lancaster 102" Dambuster

Absolutely right. I will add some weight to it so that it falls away from the plane.

Did some design and 3D printing yesterday evening. The instrument panel and air intakes for the sides of the engine nacelles. The instrument panel needs a bit of work but pretty close.

Did a bit more on the Lanc today. The fuselage is fully sheeted and filled. It has its first coat of surface sealer on ready for glassing, which hopefully I will do tomorrow.

Motor and prop arrived today so did some trials with it. It is a Turnigy G10 and I want to fly with a 3 bladed scale prop. On 3S at wide open throttle with an 11 x 7 - 3 blade prop = 10.1V, 7100rpm it is pulling 33A (330W) and producing 1660g of thrust. So 4 of these should produce 6640g thrust on a plane that will hopefully weighing in at 6 - 6.5kg. So a 1:1 thrust weight ratio. At 24A, 6400rpm it is producing 1350g thrust so more than adequate.



The downside is that the pitch speed is a little lower than I wanted. Using various motor / prop calculators, which validate my results above, show that the estimated stall speed is 30 mph and max pitch speed is 50mph so a bit tight. Could really do with 9 x 10 3 blade prop and the only one i can find is a Ramoser (statically adjustable pitch) but at 40 Euros each I will have to think about it. Alternatively a 10 x 10 2 bladed prop would be the most efficient.

Had a bit of fun with the 3D printer. Designed and printed some wheel trims and the bomb aimers glass bubble mounting flange.

A 30 mph stall speed sounds a bit frightening to me and does rather show the effect of 'scale' speed.
1/12 scale size but with 1/3 the stall speed of the full size.

I agree Q. The 30mph comes from Ecalc and is based on wing area, weight, height above sea level etc. I do not expect it to be anywhere near that based on seeing someone elses model of the same design fly last year. It was just stooging around the sky at a moderate running speed, I guess about 20 - 25mph.

The problem with this motor prop combination (11 x 7 3blade) according to eCalc is that:
50% is 26mph with each motor giving 540g thrust
57% is 38mph with each motor giving 680g of thrust.
70% throttle is 47mph & 1020g thrust each
90% throttle is 58mph & 1600g thrust each

So it would mean that to maintain safe flying speed the throttle is around 60 - 70%+. This all goes away if the stall speed is lower, say 20mph. So the lighter I can build it the better.

I am going to do a more detailed run on the numbers to see a more developed stall speed calculation rather than eCalc's wing loading guestimate.

The lipos arrived today from Hobbyking. I decided to try their 'new' graphene batteries after reading good reports from the EDF guys. They come in a very fancy box and are inside a felt pouch!! :dry: :dry:

These will sit in each engine nacelle behind the motor. According to Ecalc these should be good for 12 - 14 minutes flying well over my boredom threshold!! [badass]

They do come well-packed. I've been trying to think of a use for the hard, magnet-closed boxes! :evil:

A good job it isn't one twelfth the weight too[badass]

"They do come well-packed. I've been trying to think of a use for the hard, magnet-closed boxes!"

How about as a fireproof box to keep the battery in? LOL

It occurs to me that if you can really get 12 to 14 minutes flying time then that represents an average discharge rate of between 4 and 5 C. :ohmy: Few planes can achieve better than a 3:1 full power to cruise power ratio so even flat out it would still only be a 15C discharge.
For such an application It does raise the question as to whether "expensive" batteries have much benefit unlike the 30C + discharge rates used in many EDFs.

Thats a fair point of view Q. But when comparing the prices they were just a few pounds more expensive than the normal Turnigy or Zippy's I buy so thought I'd give them a go. All my Zippy fail/puff up/lose power after 2 seasons flying or thereabouts.

It will be interesting to see how these hold up.

Bought the wing joining tube from SLEC. Its is a 19m OD aluminium tube with 23mm OD phenolic outer tube. Couldn't believe the weight, 330g!! So I decided that I would try and make an outer tube for a length of carbon tube I had. I lubed to carbon tube with vaseline then wrapped it with a length of polythene. Easier said than done! :S :S Then I laid our some glass cloth on a polythene sheet, applied resin and rolled the carbon tube up in the cloth. Again easier said than done to keep the glass even and not twisted. Then using fingers massaged the resin through the cloth to make sure all the air was removed and glass fully wetted out. Left it overnight to cure.

Spent an hour this morning trying to get the carbon tube out of the middle of the glass tube!! Would it come out, would it b***ery. So I put it on the central heating radiator for a couple of hours then warmed it up with a hot air gun. It started to move!! Eventually after going through my repertoire of English expletives several times and and questioning the birth rights of the carbon tube I got it free. So now I have a carbon tube and glass wing tubes. Total weight 67g. [badass]

Decided to do something simpler this afternoon and cut out the parts for the engine nacelle structure and assembled them, all four of the things. They just need final sanding then fit the retract mounts and battery tray in each one and they are done.


Bit the bullet and ordered 4 Ramosa 3 blade hubs and propeller blades. The way these are designed you can statically adjust the pitch. With the benefit if you break a blade or want to change the diameter of the prop you can replace them individually. If anything happens to the Lanc I can always use them on other planes.

Hi Ralph i did a thread on here on how i do my own outer tubes, have no trouble getting them off

Thanks BB. I'll look for it and see how you did it.

Update on the nacelles. Tried fitting the vacuum moldings around the inner wooden structure. The outer nacelles are just about right. The inner ones are too deep by about 25mm so the moldings do not fit properly. I will cut the structure down and remake some parts during the week. These plans leave a lot to be desired, a lot of parts simply do not match up when assembled.

Thats where your superb building skills come in

Started the wing panels. Did the centre sections first. The original design is a one piece wing. I have redesigned the fuselage and wing so that it is two piece wing. This means infilling the fuselage and separating the wing.


Started the starboard wing. The original design does not have flaps but I wanted flaps. I have that vision of a Lancaster turning onto finals with undercarriage down and flaps down. Just looks so right. So I have redesigned the wings to have flaps.


The additional amplifier for the sound system arrived yesterday. So I can now add the 4 transducers into the wings. If you are going to do scale might as well do it as best you can. So far this build has cost £442. But that includes the 4 Vario props, 4 motors and 4 ESC's all of which can be used on other planes.

So question. The plan only shows the starboard wing layout. How do I reverse the plan so that I can build the port wing? I have heard of reversing the paper and rubbing oil onto it so that is goes semi transparent. But i do not fancy ruining the plan. Any ideas?