Probably my last big Depron plane

[quorneng]

With the wing joined together a start is made on how to install the batteries, ESC and rx in the wing.
A rough guestimate of the required CofG made it clear the battery(s) would have to go as far forward as possible which meant right into the wing leading edge at the root.
This suggested a twin arrangement either side of the central rib. The Depron battery boxes were made big enough to handle a range of sizes. The batteries would be inserted via a substantial hatch.

Note the 'magnet wire' used to connect the motors to the tiny opto 'Little Bee'20A ESCs. It is much lighter than silicon insulated flex.
Each ESC is supported vertically in a small printed holder to aid cooling.

An additional mount is added for the 8A UBEC that powers the rx and servos

For safely the motors are wired up so the inboard and outboards pairs can be supplied by their own battery.
As most of this will not be accessible everything is tested carefully both singly and all together.
The short test of all four motors mounted on the wing.

I had not realised how close it was to sucking the bedspread up into the motor.
Certainly sounds impressive!

 

[bf109g-14]

With the wing joined together a start is made on how to install the batteries, ESC and rx in the wing.
A rough guestimate of the required CofG made it clear the battery(s) would have to go as far forward as possible which meant right into the wing leading edge at the root.
This suggested a twin arrangement either side of the central rib. The Depron battery boxes were made big enough to handle a range of sizes. The batteries would be inserted via a substantial hatch.
View attachment 183768
Note the 'magnet wire' used to connect the motors to the tiny opto 'Little Bee'20A ESCs. It is much lighter than silicon insulated flex.
Each ESC is supported vertically in a small printed holder to aid cooling.
View attachment 183769
An additional mount is added for the 8A UBEC that powers the rx and servos
View attachment 183771
For safely the motors are wired up so the inboard and outboards pairs can be supplied by their own battery.
As most of this will not be accessible everything is tested carefully both singly and all together.
The short test of all four motors mounted on the wing.

I had not realised how close it was to sucking the bedspread up into the motor.
Certainly sounds impressive!

The plane looks amazing! I can’t wait until it’s finished.

 

[BoredGuy]

With the wing joined together a start is made on how to install the batteries, ESC and rx in the wing.
A rough guestimate of the required CofG made it clear the battery(s) would have to go as far forward as possible which meant right into the wing leading edge at the root.
This suggested a twin arrangement either side of the central rib. The Depron battery boxes were made big enough to handle a range of sizes. The batteries would be inserted via a substantial hatch.
View attachment 183768
Note the 'magnet wire' used to connect the motors to the tiny opto 'Little Bee'20A ESCs. It is much lighter than silicon insulated flex.
Each ESC is supported vertically in a small printed holder to aid cooling.
View attachment 183769
An additional mount is added for the 8A UBEC that powers the rx and servos
View attachment 183771
For safely the motors are wired up so the inboard and outboards pairs can be supplied by their own battery.
As most of this will not be accessible everything is tested carefully both singly and all together.
The short test of all four motors mounted on the wing.

I had not realised how close it was to sucking the bedspread up into the motor.
Certainly sounds impressive!

The wing looks kinda short, is the wing in the video without the wingtips?

 

[quorneng]

The wing looks kinda short, is the wing in the video without the wingtips?

Yes. That is just the centre section.
It carries everything but the aileron and elevator servos.

The tail plane alone is bigger and with twice the wing area of my 40 mm EDF DH Venom.

It is built just like the outer wing panels. The 5g elevator servo is positioned so it just fits between the wing skins.

With a top tape hinge it makes quite a neat, simple and even more important light installation.

Note the little printed servo arm shroud.
The link rod is actually made from a paper clip! Easy to bend and plenty stiff enough over such a short length. No adjustment you just go on making new ones until the elevator is exactly neutral from a servo tester. Done this way ensures both servos will trim from the same start position.

 

[Timmy]

Yes. That is just the centre section.
It carries everything but the aileron and elevator servos.

The tail plane alone is bigger and with twice the wing area of my 40 mm EDF DH Venom.
View attachment 184124
It is built just like the outer wing panels. The 5g elevator servo is positioned so it just fits between the wing skins.
View attachment 184125
With a top tape hinge it makes quite a neat, simple and even more important light installation.
View attachment 184139
Note the little printed servo arm shroud.
The link rod is actually made from a paper clip! Easy to bend and plenty stiff enough over such a short length. No adjustment you just go on making new ones until the elevator is exactly neutral from a servo tester. Done this way ensures both servos will trim from the same start position.

Thats a huge elevator!

 

[quorneng]

Slowly moving on. The tail plane and fin mounted on the rear fuselage.

Just a portion of local skin to be added over the tail plane. This will actually be structural as it helps support the fin.
Note there is only one servo wire as there is no rudder. Like many an EDF it will flown bank and yank. This does mean it will almost impossible to fly on 3 but then it probably wouldn't anyway. The rule is "Any sort of motor failure shut them all down and concentrate on a glide landing".
Next is to start joining the fuselage sections together then I will have a storage problem.

 

[BoredGuy]

Slowly moving on. The tail plane and fin mounted on the rear fuselage.
View attachment 184456
Just a portion of local skin to be added over the tail plane. This will actually be structural as it helps support the fin.
Note there is only one servo wire as there is no rudder. Like many an EDF it will flown bank and yank. This does mean it will almost impossible to fly on 3 but then it probably wouldn't anyway. The rule is "Any sort of motor failure shut them all down and concentrate on a glide landing".
Next is to start joining the fuselage sections together then I will have a storage problem.

Just a thought, why not use differential thrust as there are four motors? And will having such a big stabiliser made of a single depron layer be an issue regarding flex or snapping?

 

[quorneng]

BoredGuy
Actually none of the surfaces are single layers. They are all built up symmetrical aerofoil sections with 3mm Depron skins giving a maximum root thickness of 30 mm (1.125"). As a result they are surprisingly rigid.

I did consider differential thrust but the AN124 has quite significant negative dihedral so its reaction to differential thrust is open to question.
I fly many planes other than single motor EDFs 'bank and yank'. In this case I am confident the huge fuselage side area, the big fin and counter rotating EDFs left and right will ensure pretty docile handling in a banked turn.
I am more concerned at a its predicted thrust to weight of just about 50%. No problem for a high performance glider but the AN124 has a 'barn' for a fuselage.

 

[Timmy]

How heavy is it so far?

 

[BoredGuy]

BoredGuy
The motors are Emax 2205 with a racing drone 3x3.5 four blade.
The motors were on offer for four, 2 CW and 2 CCW and the same with the props. All for less than the price of a single cheap 76 mm EDF! All four together are no heavier than the EDF either.
From my point of view the attraction of such a motor/prop combination is it is quite efficient for the thrust they produce. Sort of midway between a conventional prop and a true EDF.

Are they 2300kv or 2600? Check out the bench testing on mini quad test bench, if you can fit in a four inch prop then I think you could get around 800g of thrust EACH with the right pitch and blade count.
EDIT:
Here are the mqtb test results:
2300kv:
https://docs.google.com/spreadsheets/u/0/d/1wYKeC-jX5o2-x3tqKZPkuHw57DTeBFgwrXBICZvTJ1o/htmlview
2600kv:
https://docs.google.com/spreadsheets/u/0/d/1SWG84xFVaz3w1P0SbiI9JtoIXjKydGsAaVgPbavu6sg/htmlview
Sorry I didn’t post this earlier, just reread the post where you mentioned the motors and this clicked in my head.

 

[quorneng]

Timmy
It does rather depend on what batteries I use but the best guess at the moment is 1600 g (56.5 oz).
Under ideal test condition (short leads, big battery) each nacelle just reached 250 g thrust which would be 'adequate' giving a thrust to weight of 63%. With the long wiring in the wing and a shared battery there will be some voltage drop. Hopefully not too much!

BoredGuy
They are 2300kz 2205.
Unfortunately for scale I am limited to 3" diameter so the 3 x 4 x 4 blade I have is about as good a thrust as I can expect.
They are remarkable motors. At 16V (5s?) with a 5 x 4.5 x 3 blade 1kg thrust at 30 A is claimed but I suspect only for short bursts.

The full fuselage. It is enormous!

Then there is the problem of how to take it somewhere to fly. Now in one piece I am not at all sure it will fit in my car.

 

[Hondo76251]

That is awesome! If i had that much work into one i dont think id be brave enough to fly it!

 

[BoredGuy]

Timmy
It does rather depend on what batteries I use but the best guess at the moment is 1600 g (56.5 oz).
Under ideal test condition (short leads, big battery) each nacelle just reached 250 g thrust which would be 'adequate' giving a thrust to weight of 63%. With the long wiring in the wing and a shared battery there will be some voltage drop. Hopefully not too much!

BoredGuy
They are 2300kz 2205.
Unfortunately for scale I am limited to 3" diameter so the 3 x 4 x 4 blade I have is about as good a thrust as I can expect.
They are remarkable motors. At 16V (5s?) with a 5 x 4.5 x 3 blade 1kg thrust at 30 A is claimed but I suspect only for short bursts.

The full fuselage. It is enormous!
View attachment 184522
Then there is the problem of how to take it somewhere to fly. Now in one piece I am not at all sure it will fit in my car.

Oh man, that’s huge. If I were you though, I still would upsize the nacelles-having such a beautiful plane so underpowered seems like a bit of a risk, and I don’t think anyone would be able to tell the difference-kinda like EDF kits having bigger intakes and cheater holes than the plane they are based off of.

 

[Timmy]

Its awesome how the build has progressed! I can't wait for the wing to be put on! Are they gonna be removable?

 

[Grifflyer]

Incredible build! I just found this thread and this is such an amazing project!!

 

[quorneng]

BoredGuy
You well maybe right about the nacelle size but I am basing my judgement (guess?) on the experience with my Depron Airbus A350 - 900 which uses two of the same motors and props in scale size nacelles.

Built in much the same way as the AN 124 it is just under 1/2 the weight but with only 1/3 the wing area. It has 'adequate' thrust so it can 'cruise' satisfactorily on reduced power.
I surmise the AN 124 with its significantly lower wing loading will fly slower which will make up for its less streamlined fuselage.
At least the Antonov will belly land on its fuselage rather than on the engine nacelles as does the A350 which requires the gentlest of touch downs to avoid difficult to repair damage.
We shall see!

 

[Flyingshark]

BoredGuy
You well maybe right about the nacelle size but I am basing my judgement (guess?) on the experience with my Depron Airbus A350 - 900 which uses two of the same motors and props in scale size nacelles.
View attachment 184556
Built in much the same way as the AN 124 it is just under 1/2 the weight but with only 1/3 the wing area. It has 'adequate' thrust so it can 'cruise' satisfactorily on reduced power.
I surmise the AN 124 with its significantly lower wing loading will fly slower which will make up for its less streamlined fuselage.
At least the Antonov will belly land on its fuselage rather than on the engine nacelles as does the A350 which requires the gentlest of touch downs to avoid difficult to repair damage.
We shall see!

@quorneng -- That A350 is beautiful! Is all of it made of depron?

 

[quorneng]

Yes. All 2mm Depron apart from 2mm thick balsa spar flanges out as far as the nacelles. Like the Antonov the wing ribs and fuselage formers are printed. It only draws 10A in total so manages quite nicely on a tiny 1000 mAh 4s battery.
It does fly very nicely, particularly with the aid of a gyro rx.

 

[quorneng]

Finally assembled the AS124.

Given the weather and the need for calm conditions I will give it some paint before the maiden. The lightest scheme is more or less a light white 'wash' over the white Depron but a stronger gloss colour on the fuselage underside for both visibility and to improve the scuff resistance of the Depron for belly landing.

 

[Timmy]

Finally assembled the AS124.
View attachment 184945
Given the weather and the need for calm conditions I will give it some paint before the maiden. The lightest scheme is more or less a light white 'wash' over the white Depron but a stronger gloss colour on the fuselage underside for both visibility and to improve the scuff resistance of the Depron for belly landing.

looks awesome!