A tiny scale plane

I have two small brushed motors with 2.5" dia props.

I have been thinking of what to do with them for some time.
The 3.5oz Frog Wren at 25" span flies very well so I imagined some sort of 'twin' but I wanted it to be scale.
The next problem is they are not very well matched for power, one has noticeably stronger magnets.
A 'tandem' twin would solve that but being brushed motors it will have to have an efficient airframe with a reasonable wing area and look scale with no undercarriage.
So a Cessna Skymaster or rather the military version the O-2.

Simple paint job, interesting USAF insignia!

Oooooo this looks an interesting build! Will look forward to seeing you do this one

Whats the wire from the twin tail to the wing for?

I am looking forward to this build, I would say you should build the Cessna with them! There is a full size one up the road from me at my local airfield and it looks/sounds great! Going to keep my eye on this!

The O2 will be built along the same lines as the Frog Wren in 2mm Depron.
I rather expect it will be somewhat under powered with the brushed motors so it may be converted to brushless at some point.
28" span. The wing should be quite efficient.

As it has wing struts it will be a 'one' piece plane with everything permanently fixed.
Elevator and aileron control with the servos in the wing at the front of each tail boom.
The motors weigh 1oz so my target is 5oz with an 800mAh 2s.

Well I have problem
I have tile printed the full plan to a 28" span and it all looks very nice but there is no way the resulting plane would be adequately powered by those particular tiny brushed motors or even look sensible.
There are some options:-
I could make it smaller, it would have to come down to about 20" span, but as the overall weight would still be similar it might not even fly at all.
Or
I could use brush less motors but the whole point of the exercise was to use the brushed ones!
Or
I could build a simple non scale plane to use the brushed motors.

On reflection I think this is what I will do.
But
The Cessna O2 is a very nice subject and should give a stunning performance so it will be back!

I'm not sure I do 'cobble up'!

After a bit of testing (a bit of a story in itself!) the brushed motors appear to be reasonably well matched so they can go into a simple tractor twin but with a gull wing to keep the props clear of the ground.

The 'new' Cessna O2 will be a big bigger than originally proposed at about 36" span and hopefully with the capability of shutting down one motor in flight - if you going to have a tandem twin you might as well make use of it!

Strictly the title is no longer correct as its now just "A tiny plane", in fact its a Twin Wren!
The motors mounted on my 'spare' Frog Wren wing.

This wing will be permanently fixed to a new fuselage.
The only brushed ESC I have is rated at 20A so it should be big enough.

The wing attached to a new part built Wren fuselage.

I think the battery will go in the cockpit area but I cannot be sure until the tail feathers and servos are in place.
As it is not really a Wren any more it will have a single fin and rudder..

I did something very unusual today I destroyed two airframes!
I normally like to keep everything I make even if no longer flyable but my absolute lack of space meant I had to make some room. One was already stripped of bits but the other was completely flyable.
There is now a pile of Depron bits in the bin!
However some of the leccy bits will go into the Twin Wren.

The rudder and elevator servos are mounted in exactly the same way as on the Wren - glued together to form a 'servo block' that fits exactly across the inside of the fuselage just behind the wing..
It looks like the Twin Wren will weigh about 1/2oz more than the single. Not too bad seeing as it has brushed motors.

A first run of the motors restrained by a big chunk of lead. It makes quite an interesting noise.

The ESC and radio installed under the wing.

The final job is to position the battery to give the same CofG as the other Wren.

Klipkopwildlife
These motors are supremely cheap with 'bent metal' brushes (but they do at least have carbon/copper blocks) but the whole assembly is just 10mm diameter so any adjustment is not really possible.
I am fairly certain the problem is the magnets or rather one of them. One motor has 6 distinct equal steps as you turn it. On the other the steps are less well defined and not so equally spaced. I suspect on of the magnets on that motor is weaker than the others.

That was one of the reasons I made the video to check the sound. There is only a slow 'beat' so either they are running at similar revs or they are a whole order different!

Just to be safe the motor are mounted as close to the fuselage as possible and it has a generous fin and rudder!

All finished along the original

Can you have a brace of Wrens?

I expect the fin and rudder will be cut down a bit after some flight testing.

Now I can start thinking about that Cessna O2!