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DB Cirrus Moth 40 Electric build

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martin collins 121/10/2020 21:40:13
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475 forum posts
212 photos

This is a build log for my next project, it is an old DB pre laser cut Moth 40, i am hoping to keep it light to fly on 3s, i have Gens Ace 4000mah pack which will go up against the old i.c bulkhead and the motor is going to be an EMAX BL2820/07 I had used in an airframe which got sold on, prop is 12x6 APC E.

The pack weight should help with the c of g but i will aim to try and keep it light at the tail end. Colour scheme has already been chosen, more of that further on into the build, suffice to say the full size has an interesting story behind it. Any advice or thoughts as i go along will be appreciated, i hate a silent build log! Pics of any others built from the DB kit also welcome, first build update and pics tomorrow evening...........M

Geoff S21/10/2020 22:29:54
3902 forum posts
57 photos

i chose to power mine on 4S. I use an Emax GT3526-05 (710kv) with a 13x6.5 prop. A 4AH LiPo gives me a reasonable 9/10 minute endurance. The battery is housed beneath the motor with access from the front and the model needs no ballast to get the CoG in place.

Actually mine is a Gypsy Moth as flown in the film 'Out of Africa' and I made a different, Tiger Moth style undercarriage.

Here it is on its second flight before I fitted dummy elastic flying/landing wires.

_mg_5636.jpg

I love it. It's probably my favourite model and it's had well over 50 flights - pehaps a 100 (I don't keep a score)

Geoff

 

Edited By Geoff S on 21/10/2020 22:32:09

martin collins 121/10/2020 22:52:21
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475 forum posts
212 photos

Nice looking Moth Geoff, do you have a picture of the battery/hatch area?

Geoff S21/10/2020 23:31:12
3902 forum posts
57 photos

Notan actual picture but this is where te battery fits:

battery placement.jpg

Part 148 is made into an access hatch.

Here's the motor installation in progress:

fuselage 3.jpg

I have a removable link between one of the esc/ motor connections to disable the motor so I don't chop off my fingers inadvertently That, coupled with a transmitter based motor disable switch, seems to be good protection.

Geoff

martin collins 123/10/2020 23:37:00
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475 forum posts
212 photos

Progress so far has concentrated on the lower wing panels, built as per plan except holes made in ribs for the wing servo wiring and i have moved the spar webbing on a couple of bays as per suggestion in other builds to help with the leading edge sheeting glue surface area. Tomorrows aims are to fit the wing tips, top trailing edges and front leading edge sheeting, anything beyond that will be a bonus. img_20201023_232002_resized_20201023_112020855.jpg

Goose is the real hero24/10/2020 10:41:56
55 forum posts
7 photos

Hi Martin, great to see you have made a start on this. Watching with interest...

martin collins 124/10/2020 11:03:13
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475 forum posts
212 photos

Hi Robert, yep it is now underway so you will get to see it built! Fair bit more sanding and shaping than a laser cut version but not a problem. I think you will be interested in the plane i have chosen to model it on but i am keeping that under wraps till i am a bit further down the road.

Jonathan M24/10/2020 11:06:01
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870 forum posts
335 photos

Also watching with interest!

Mine is the smaller 20 size version, still in kit box, destined for a 30 four-stroke, will be my first scale model once I eventually get round to building it...

Goose is the real hero24/10/2020 11:15:05
55 forum posts
7 photos
Posted by martin collins 1 on 24/10/2020 11:03:13:

Hi Robert, yep it is now underway so you will get to see it built! Fair bit more sanding and shaping than a laser cut version but not a problem. I think you will be interested in the plane i have chosen to model it on but i am keeping that under wraps till i am a bit further down the road.

Interesting - I await the big reveal!
Really glad to see this getting built rather than mouldering away in my loft, grateful for the build log as it will help me when I get round to my Tiger Moth too!

Stuphedd24/10/2020 14:02:33
730 forum posts
376 photos

with ref to Jonathan M

I too have a 20 size DB Moth very old kit given to me last Christmas on the basis I built and flew it which I did over this last winter .

I carried out some mods , like convert it to electric , used a complete system from a leccy Acrowot of ebay . , put in lower wing ailerons and reduced the down thrust and top wing incidences to make the engine line look " more realistic , because I mocked up a Genet radial to be a bit different, Also beefed up the cabane , It flies very well and steady , I am not a "scale" man so there are anomalies !wink

I have lots of build photos and a vid of its very first flight I have put photos of it elsewhere but just in case!img_1927.jpg

Geoff S24/10/2020 15:37:54
3902 forum posts
57 photos

Looks like yellow/black schemes are popular. I can vouch for good visibilty whilst in the air which was the reason I chose to model the Gypsy Moth flown by Robert Redford's character in 'Out of Africa' where there's quite a long flying scenes swooping low over herds of zebra etc. It's on Netflix if you have access and recommended for the flying alone (I like the story, too).

I'm not a real scale modeller but I do like scale features which is why I have closed loop control of both rudder and elevator exiting the fuselage in scale positions.

Glad to see you're making progress, Martin. I love biplanes but not so keen on building wings which is a bit odd I suppose I find ailerons on the bottom wing only perfectly adequate for scaleish aerobatics - which is all I'm capable of anyway.

Geoff

Stuphedd24/10/2020 17:08:13
730 forum posts
376 photos

Mine was going to be silver and red but I had not got enough silver to complete the whole plane where as I had plenty of yellow and black .And as you say its very visible !

Bottom wing ailerons allow mine to do slowish rolls but needing a lot of elevator and rudder to make them look good !Yet to be perfected !blush

cheers

Jonathan M24/10/2020 21:16:59
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870 forum posts
335 photos

Interesting to hear all the above. I'm still honing my general flying skills with sports models, so by the time I get mine built (at least its a 'stand-off scale' design!) I should hopefully have become a bit more convincing with things like using the rudder appropriately etc. I was inspired to buy the 20-sized one after seeing this video (which seemed to prove that the small version could be made to fly very nicely indeed in the right hands):

Edited By Jonathan M on 24/10/2020 21:20:45

martin collins 124/10/2020 21:19:38
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475 forum posts
212 photos

Will do a little bit more tonight but have got the lower panels more or less finished, just about to cut some corner pieces for the servo mounting hatches. The panels will be removed in the morning and the top wing panels started. Will do an update once they have been built and will unveil the chosen colour scheme then, enjoying the build so far, i know they fly great so this one will not be a nail biting maiden when ready.

img_20201024_205922_resized_20201024_085943596.jpg

martin collins 124/10/2020 21:24:04
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475 forum posts
212 photos

You do not need to be proficient with flying it by rudder, i will have rudder mixed in with the ailerons so that when turning with ailerons a percentage of rudder is used as well with no extra input from the rudder stick. A lot of biplanes require this to help the turn....................

Stuphedd24/10/2020 22:32:49
730 forum posts
376 photos

I totally agree with mixing the rudder and ailerons, essential on this model ( and many others not only bipes ).My first flight showed it fighting the bank mixed a little in the rudder and its spot on , For anyone you has flown a full size Tiger Moth will know that the turn is initiated with a touch of rudder,

Its a BIG rudder so you only need a tad .

cheers

Geoff S24/10/2020 23:10:38
3902 forum posts
57 photos

Obviously it's always better to get balanced turns by adding rudder and ailerons but if you have sufficient aileron differential (2 x up versus down) to limit adverse yaw then the DB Cirrus and Tiger Moths can be flown one handed (on mode 2) perfectly well. I like to add a little rudder just for the satisfaction but it's not absolutely necessary. I did have some rudder/aileron mix but never use it.

They are absolute pussy cats - at least both mine are.

The guy who took the photo of mine on its second flight (see above) asked if there was some problem because it appeared a little unsteady. It wasn't the model that was unsteady it was me I really hate maidens of models I've built but needs must when there are no mode 2 pilots who are sufficiently better than I am - apart from Ian Redshaw and he's rarely there when I am.

Good to see your build progressing.  I was glued to Eurosport watching the penultimate stage of the Giro d'Italia with my wife so got nothing done at all.

It's probably worth having a look at Dwain Dibley's Cirrus build about 3 years ago if you get a bit stuck.

Geoff

Edited By Geoff S on 24/10/2020 23:15:01

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