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May 12, 2016, 04:34 AM
It's time to buzz the tower
nklkn's Avatar
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Build Log

OV-10 Bronco


Here's my latest scratch build: a 6mm depron OV-10 Bronco.

Wing Span: 44.5"
Weight: 45-50oz
Wing Area: 378.25"
Wing Loading: 17-19oz/sq.ft.
Wing Cube Loading: 10.6-11.7

Power system:
NTM Prop Drive Series 35-30 1100kv / 380w - (2)
Turnigy Plush 30A ESC - (2)
Single battery used. Successfully used
2200maH 25C 3s (7 min flight times)
2200maH 35C 3s (7 min flight times)
3700maH 25C 3s (11 min flight times)
8x6 Master Airscrew CW+CCW 3-blade props

Balance point is best at around 28% MAC

This is my first electric twin and also my first depron build using an airfoil (clark Y). It is a joy to fly and is very docile in the air. It handles a bit of wind easily and best of all looks fantastic in the air. I went with no landing gear or flaps for simplicity but you could add them easily. The build itself is simple although shaping the canopy and nose to achieve a scale look is a bit of a challenge. Power-wise it is fine for my taste but you could put a larger prop/motor combo and get a faster plane. I went with an 8" prop as it is less likely to get caught in grass.

I think all the templates are there but if there's something missing or want more info about, just post a question.

IMPORTANT NOTE:

I deviated from the plans in some areas:
- There is an error in the width of the tail plane in ov-10-bronco2.pdf. Use ov10-tail2.pdf for your template.
- The wing-to-fuse mount was improvised. Read the build photo comments for more info.
- I used a 5mm CFT spar instead of the 4mm spar in the plans.
- I made balsa access hatches in the top of the wing over each boom for motor wire access.
- I moved the aileron servos and made the ailerons bigger from what is in the plans.


Enjoy!

Neal
Last edited by nklkn; May 13, 2016 at 07:25 PM.
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May 12, 2016, 05:28 AM
It's time to buzz the tower
nklkn's Avatar
Thread OP

Photos


This is mostly a simple build with some notable exceptions: the canopy and nose section was a challenge to shape correctly to get a scale look. Also getting everything square is challenging as you have two booms and two motor mounts to deal with.

I also abandoned an idea for the wing-to-fuse connection. I opted for a single nylon screw through the top of the wing into a receiving nut that is epoxied into a plywood frame glued to the fuse.

I've learned a lot from this build and there are things I'd definitely do differently if I build it again.
Last edited by nklkn; May 13, 2016 at 07:14 PM.
May 12, 2016, 09:21 AM
Jer. 29:11
jeffsch's Avatar
Congratulations! It does look nice.

Quick questions:

* What CoG do you recommend?

* What do you recommend for the battery hatch?

* What are the square ply doublers with holes on the side of the fuselage for?
May 12, 2016, 07:41 PM
It's time to buzz the tower
nklkn's Avatar
Thread OP
I can't remember the exact measurement but if you take 28% of the chord length you will find that number!

The battery hatch is under the canopy. I just improvised the hatch with magnets... works fine.

You should ignore those square ply doublers. They were an early attempt at holding the wing to the center fuse; but in the end I just used a nylon screw through the wing to a receiving nut inside the fuse. I'll post some photos of that if you want.

Neal
May 13, 2016, 01:46 PM
Registered User
Nice build. I've been wanting a good OV-10 project, any other photos and hints would be helpful
Thanks
May 13, 2016, 06:08 PM
It's time to buzz the tower
nklkn's Avatar
Thread OP

More Photos


Unfortunately I didn't document this build very well because I honestly didn't think it would come out as well as it did!

For anyone interested the photos below have some build info that might assist you if you want to have a go. If you have questions or need more photos just ask! Happy to help

Neal
Last edited by nklkn; Jul 18, 2016 at 03:32 AM.
May 13, 2016, 07:50 PM
Registered User
Hey thanks, it adds a lot of help. Really like the detail you did.
May 14, 2016, 03:43 AM
Foam is where the heart is
brett.c's Avatar
Very nice effort.
Not many plans around for this size so good to see that you have provided us with some.

I built mine from MPF a few years ago and it is still one of my favourite planes.
Very forgiving and easy plane to fly.
Look and sound nice in the air too.
May 14, 2016, 03:59 AM
Registered User
Nice plane,do u have this plane's flying video?
May 14, 2016, 03:03 PM
Registered User
Another nice build
May 15, 2016, 09:18 AM
Registered User
rajazo's Avatar
beautiful Bronco Nklkn!!!
I will adopt lot of your ideas in the next iteration of my easybuilt version.
I will check your motor position because mine needs some down thrust to keep it leveled at full throttle.

thanks a lot for this new version and plans
May 15, 2016, 06:24 PM
It's time to buzz the tower
nklkn's Avatar
Thread OP
Thanks guys!

Brett.c I used your model for a lot of inspiration. How did you do the cowls? Does your model have a removable wing?

I don't have a video yet but the model is very gentle and stable. Very scale in the air. Hand launching is an absolute breeze with the counter rotating props.
May 15, 2016, 11:00 PM
Foam is where the heart is
brett.c's Avatar
Quote:
Originally Posted by nklkn
How did you do the cowls? Does your model have a removable wing?
The cowls are made in box form from 5mm mpf with bits added for the intakes etc. Then sanded into shape. The good thing with mpf is that it can be curved to suit the shape you want.

The wing is glued to the main fuselage. I was going to make it removable, however that got a bit too complicated for me. This would have made installing the wiring jumble a lot easier, as I note with your build.

A big problem I had after the build was flex between the booms and I note that you took this into account. Good move.

I find the rudders almost useless and I use a bit of differential throttle instead. Therefore I will remove the rudder servo and complex linkage setup.
May 17, 2016, 01:29 AM
It's time to buzz the tower
nklkn's Avatar
Thread OP
Quote:
Originally Posted by brett.c
The cowls are made in box form from 5mm mpf with bits added for the intakes etc. Then sanded into shape. The good thing with mpf is that it can be curved to suit the shape you want.

The wing is glued to the main fuselage. I was going to make it removable, however that got a bit too complicated for me. This would have made installing the wiring jumble a lot easier, as I note with your build.

A big problem I had after the build was flex between the booms and I note that you took this into account. Good move.

I find the rudders almost useless and I use a bit of differential throttle instead. Therefore I will remove the rudder servo and complex linkage setup.
I thought you vac-formed those cowls! They look really nice! I thought about cutting the cowls off just in front of the motor mount and adding depron bits and pieces to achieve the same thing. Maybe I'll give it a go. They would need to be removable so that I can get to the motors if necessary.

I didn't really do much to address the flex in the booms. I laminated the tailplane and fins so that they are 12mm thick and epoxied them together. There's some flex but not that much to be problematic.

I find the rudders in my model very effective. I always build in rudders in any model but this one in particular seems effective especially in cross-winds and some aerobatic manoeuvres. They weren't that hard to install as I just located them on the insides of the booms. The elevator wiring and location was more complicated. I like the differential throttle idea though.

Neal
May 17, 2016, 09:04 AM
Foam is where the heart is
brett.c's Avatar
Get some knauf foam board from Bunnings. It comes in 30mm and 50mm thick sheets and is quite cheap. It can be carved and sanded nicely.
I used it to make the cowling on this plane. It attaches to the firewall using some bamboo dowels and adjacent holes, with magnets to keep it in place.


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