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Depron 134" Lancaster.

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Ian10127/12/2014 20:49:07
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225 forum posts
323 photos

Seasons greetings.

This is something I have been messing with for about 6 months, on and off, well more off than on! It is likely to take the same time again, so please be patient.

The plans and plastic mouldings are all Tony Nijhuis, but the build 'style' is not Tony's. If it doesn't work, I can't blame him. I have had the drawings for a year now, can't rush these things.

I built the TN 72" Spitfire in mainly depron and it flies amazingly well. Being about half of the plan weight gives it scale flight (in my opinion). The goal with this Lancaster is to do the same. Plan weight is 23.5 lbs, hopefully it will end up about 14 lbs or less. Having very little building experience and even less patience, it will be a challenge for me.

I don't know how often I will be able to do updates, but I will try to keep them coming. Time is always in short supply!

Anyway, started with a long box. My other builds have been around a cruciform, but because of the size, I went for strength with a little ply reinforcing along the way. The box on it's own is quite rigid and very straight. The formers are taken straight from Tony's plans, but altered to make the traditional Lancaster, not the dambuster version.

The nose section slides out of the main box and will contain the batteries. I think this may make it nose heavy, but we will see later. I have also tried to make the front turret swivel (not powered, just with a weight and gravity).

A bit of paint and a picture and the bomb aimers window ready for skinning.

Formers in position.

Where the skins will join on the top is thickened up for extra glue area.

Can't have a Lancaster this big without having bomb doors. I made these on the fuselage so hopefully they fit properly! Once removed I was surprised by how they stayed something like the correct shape even if they are a bit flimsy.

To keep the doors closed and to give them support while they are open, I have used a 6mm aluminium tubes with 3 arms, rear, middle and almost front(the 1m tube from B&Q was not long enough for the massive doors). I have also reinforced the hinge side of the doors with a bit of spruce. With a masking tape hinge, it all seems to work ok. Haven't decided yet what sort of hinges to use.

Doors skinned and dropped on to check alignment. A bit of tweaking and not too bad!

Because I have a DX6i, I am short of a channel! I am going to use my old 35mhz jobby to operate the bomb doors and bomb release. This isn't a bad idea apart from the extra weight, as any problems with the mechanisms will not interfere with the flight battery. The retracts will also be separate from the flight battery along with the motors. Clear as mud. 3 sets of batteries, flight batt, motor/retract batts and bomb batts. My son is quite excited about operating the bombs, assuming it ever gets off the ground.

Anyway, that's it for now.

Regards Ian

Electriflier27/12/2014 21:42:03
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474 forum posts
1210 photos

Ian, wow! This is going to be a winner!

I'm thrilled that you've decided to post up the build log - subscribed!

if it turns out half as good as the Spitfire, (which I'm confident it will), it will be a beauty.

So looking forward to seeing this build progressing.

Roy

Ian10128/12/2014 08:44:29
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225 forum posts
323 photos

A little bit more:-

Bomb release mechanism will be from 1 servo via a snake connecting up the 10 bomb bays.

1.2mm copper coated welding wire will hold the bombs. Wire is glued in at the required drop angle, bombs slide on then hook the wires over the catches. Super simple! Hopefully the bombs will slide off in some sort of order, rather than them all fall out together. Don't know yet whether to have 60 small bombs or 48 bigger bombs. Might go for 48 as it will be less work and easier for a young helper to find!

Bomb loaded (finished bombs will be a bit better hopefully!)

Bombs released.

Ran out of wire to finish. Also need to get another servo before finishing the release mechanism.

bouncebounce crunch28/12/2014 08:59:57
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1739 forum posts
212 photos

looking great Ian

maybe a little idea of a dot of metal in your bomb surface, that way you could have an old stereo speaker on the end of a spade handle to pick them up. my ideas don't always work so caution.

cheers. bbc

Ian10128/12/2014 09:01:37
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225 forum posts
323 photos

That's up to date nearly.

I have installed the receivers/ubecs and a mile of wiring. Receiver batteries will go in small pockets either side of the removable nose.

Props are 15 x 8

Motors are DYS A3548-05 900kv 770watt.

I bought 1 motor and prop to test before ordering the rest. With a 3s 3000mah battery (which is what I want to use as I already have some), I got 410 watts at 43 amps. I think it will fly on about 250 watts per motor or less, based on Tony's info which is about 25 amps. Hopefully I should be able to use 40amp esc's.

That's about it until I find some time to do a bit more!

Regards

Ian

Edited By David Ashby - RCME on 16/01/2015 15:53:43

Dave Hopkin28/12/2014 09:07:01
3672 forum posts
294 photos

Impressive!

For the bombs a bit of ferrous metal in the nose might help them to fall out and drop vertically and would help in finding them afterwards, as BBC says a magnet on the end of a broom handle to "bomb sweep"

Shall be watching this with interest

Ian10128/12/2014 09:13:29
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225 forum posts
323 photos

Thanks guys.

The bomb has got a bit of broken motor shaft shoved in the front. It's good to keep those bits of scrap sometimes. It has been thrown across the garage a few times to test, but I think they need to be much heavier or they will just blow away with the wind. Should be able to carry a bit of weight, after all, that's what it was designed to do!

Ian

Depron Daz28/12/2014 20:20:43
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760 forum posts
173 photos

Absolutely brilliant Ian, well impressed!

You do know that this means that Roy will want to build one twice as big LOL surprise

All the best with this project, I'll keep an eye on this one for sure!

Andrew Price 228/12/2014 21:58:40
815 forum posts

Signing in, with interest.

Simon Chaddock28/12/2014 23:18:14
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5405 forum posts
2824 photos

A spectacular build but if the motor is capable of drawing 43A it would seem unwise to limit yourself to a 40A ESC.

An ESC failure resulting from a burst of full power at low speed could be very serious.

"Spoil the ship for a ha'porth of tar"?

Ian10129/12/2014 09:16:34
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225 forum posts
323 photos

Simon you are correct.

The esc's I was thinking of using were Overlander 40amp continuous, 55 amp for 10 seconds. Hopefully it will plod around at half throttle or less, but that element of doubt is always going to be there! Maybe I will go bigger.

I looked at the quad esc route that Electriflier went down with his Hercules, but I want to keep all 4 power systems separate.

I have been fascinated by your building techniques (been watching from afar).

Ian

Ian10129/12/2014 09:22:47
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225 forum posts
323 photos

Just a thought. Has anybody tried re-shaping the propeller tips to make them look symmetrical.

I thought about making a template and having a go, but not sure about what might happen to the performance.

I know I would have to re-balance them.

Tony Bennett29/12/2014 09:26:20
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5074 forum posts
129 photos

fascinating.

Dave Hopkin29/12/2014 09:31:55
3672 forum posts
294 photos
Posted by Ian101 on 29/12/2014 09:22:47:

Just a thought. Has anybody tried re-shaping the propeller tips to make them look symmetrical.

I thought about making a template and having a go, but not sure about what might happen to the performance.

I know I would have to re-balance them.

Thought about it quite a few times... plucked up the courage to do it..... not yet!

Depends if you are willing to sacrifice a prop on the test bed and see what happens I guess

I guess you would need a way to measure pretty accurately the thrust before and after the surgery to understand the effect you would have on the prop

Bob Cotsford29/12/2014 09:45:02
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7874 forum posts
433 photos

I can't imagine reshaping the prop tips will have any drastic effect on thrust, in fact i think it will have more effect on noise levels. Even then it shouldn't be more than a dB or two. We have used square and round tipped props for decades, the scimitar tips are a relatively recent fashion.

Pretty impressive build for a pizza tray!teeth 2

Simon Chaddock29/12/2014 13:02:29
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5405 forum posts
2824 photos

ON the subject of bade shape the Lancaster used both "tooth pick" and "paddle blade" props.

My gut feeling is that at model sizes the paddle blade with its broader chord is likely to be more efficient although on the full size it appears it had more to do with availability than any significant difference in performance.

In single seat fighters where there was a limit on maximum diameter the paddle blade became the only option to absorb any increased engine power.

Ian10101/01/2015 22:02:27
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225 forum posts
323 photos

Thanks for the comments and the prop information. I shall have a go at re-shaping them later in the build.

Managed to get a little bit more done. Did the first bit of skinning so I could have a go at the cockpit canopy. I am quite impressed with all of the plastic stuff. Got it to fit quite well for a quick trial fit.

The problem I have now is moving it and not damaging the surface. All of a sudden it seems to have got quite big! I think I may buy a large bit of soft foam to lay on the workbench.

Happy New year to one and all.

Ian

Tony Bennett01/01/2015 22:57:01
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5074 forum posts
129 photos

that looks impressive sir.

how strong is the skin between the formers.

Ian10102/01/2015 07:13:55
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225 forum posts
323 photos

Thanks Tony.

There are still more ribs to go in where I haven't covered yet, but the skin seems fine. Obviously as the weight goes on I will have to be careful to spread the load with my hands, not just use fingers, but can't see it being a problem. You will have the same with your Trent Meteor.

Can you remember what weight your big Lancaster was?

Tony Bennett02/01/2015 07:22:22
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5074 forum posts
129 photos

the big one i did turned out to weight 23lb 5 oz without batteries.

i found you need more formers with depron than you would need with balsa.

but the weight of an extra depron former is negligible anyway.

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