How about a twin?

Vipertech13 · Post by **Vipertech13** » Tue Jan 06, 2015 6:08 am

Winter brings too much free time for a scratch builder, I start thinking of the next plane and I don't have my balsa project finished but I need some parts. While I wait for those the brain kicks in and I'm off on another foam scratch build! I want a twin but which one? My search of twins leads to the Vulcan Air P68C. I like the overall look and it's a twin! I started with the original dimensions.

: P68C-ExternalView-Up.jpg (20.49 KiB) Viewed 6621 times

: P68C-ExternalView-Side.jpg (16.9 KiB) Viewed 6621 times

: P68C-ExternalView-Front.jpg (23.84 KiB) Viewed 6621 times

I scale them down from feet to inches and I use windows 7 paint and format it to the dimensions of Adams foam board 20 x 30 inches. I stretch the original jpg. picture to the size I want it to be in Paint then touch it up as needed. then I can print it as a full size plan.
I should do a demonstration on that process at some point!?
So here is the plane progress in just a few days.

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I made a steerable nose wheel from scratch you can sort of see it, I forgot to take the picture before gluing on the nose cover.

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The wing with the motors

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And an overall look at the progress

Tony · Post by **Tony** » Tue Jan 06, 2015 7:35 am

That is just totally amazing Gerald, can't wait to see this bird in the air... Nice one. What electronics are you going to use?

cml001 · Post by **cml001** » Tue Jan 06, 2015 10:43 am

Oh yeah!

Graham Lawrie · Post by **Graham Lawrie** » Tue Jan 06, 2015 11:24 am

Very good Gerald:) I have never done a foam build, but would be interested to see how you do the plans on windows:)

Post by **danhampson** » Tue Jan 06, 2015 4:26 pm

Nice build Gerald. You've got some good projects going on this winter.

Vipertech13 · Post by **Vipertech13** » Tue Jan 06, 2015 6:26 pm

Tony wrote:That is just totally amazing Gerald, can't wait to see this bird in the air... Nice one. What electronics are you going to use?

Thanks, the electronics will be 2, 20 amp esc's, 2, ST2204 1500kv HK Donkeys, they are cheap but work really well for $6.05 us, ORX six channel RX, 2 1500 or 1800 Mah 3s batteries, one for each engine. That way if one conks out I might have a shot at saving the plane. I will most likely use a RX battery just as a precaution instead of relying on the ESC BEC circuit. Kind of over kill but safety forced! Will use 9 gram servos. Still some details to work out like will I do a flaperon setup or do differential thrust Hummmm... I can tell you that the plane fuse is 30" long and wing span is 39.5" with a 6" cord KFM3. I don't have a weight yet but I am aiming for 24 oz or less as my motor set up will have 28oz of thrust! Cutting it close but I think she'll be ok.

Vipertech13 · Post by **Vipertech13** » Tue Jan 06, 2015 6:33 pm

Graham Lawrie wrote:Very good Gerald:) I have never done a foam build, but would be interested to see how you do the plans on windows:)

Thanks, I will be looking into a way to make a video demo of the process I used to design and build as I have had requests from guys at the field to do a demo of 1 of my builds, The 1 Sheeter Bush Beater, people go nuts over it when ever I bring it to the field. Just have to find the time!

Post by **danhampson** » Tue Jan 06, 2015 6:35 pm

That would make a cool thread Gerald. I wouldn't know where to start, well some foam board would be good lol.

Vipertech13 · Post by **Vipertech13** » Tue Jan 06, 2015 6:35 pm

danhampson wrote:Nice build Gerald. You've got some good projects going on this winter.

Thank you! Yep many projects going on and my Formosa II came Fed-EX today! Wife is going to FLIP!

Post by **pvolcko** » Thu Jan 08, 2015 2:27 am

A word of caution on using two separate batteries. That means that you will likely be running the motors at different speeds. That was already going to be the case due to variances in the windings, but with separate batteries you're going to make it worse as the batteries will have different voltage and will discharge in different rates during the flight. If you want to run two batteries, that's fine, but I'd suggest running them parallel instead of having them completely separate (one to each ESC). If you do end up running one to each ESC, make sure to tie negatives together so you have a common "ground" for the whole system and don't have any loop currents flowing through the Rx or ESCs (especially if you're using non-opto isolated ESCs).

Vipertech13 · Post by **Vipertech13** » Tue Feb 03, 2015 7:19 pm

So I finished the Formosa now the twin is on the bench again. I have opted for the single battery for the motors and a separate RX battery to save weight yet add a measure of safety. The esc are non opto so I disconnected the red 5 volt lead from the connector and taped it back, then connected them to a "Y" harness. I designed nacelle covers and a channel guide/cover for the wires and esc's.

: Nacelles; IMG00092.JPG (506.66 KiB) Viewed 6578 times

: Nacelles and channel; IMG00093.JPG (686.7 KiB) Viewed 6578 times

: How it lays out; IMG00094.JPG (743.96 KiB) Viewed 6578 times

The channel and nacelle have enough room for air flow, so should be ok there.
I won't be horsing this unit around, more easy, scale flight.
Here is how it looks assembled.

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: Nacelle underside view; IMG00105.JPG (681.63 KiB) Viewed 6578 times

Rear servos are mounted

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Steering servo mounted

: Steering servo; IMG00100.JPG (681.87 KiB) Viewed 6578 times

The rudder and steering servos are on a "Y" cable.
Need to decide on size of ailerons yet and if I will add flaps or just mix flap and ailerons?
Need to make battery compartment on the bottom, enclose the cabin and bottom of the fuselage and put on some kind of finish.

Tony · Post by **Tony** » Fri Feb 06, 2015 12:43 pm

This is looking awesome Gerald. Nice build. Take note on what Paul is saying regarding separate batteries...

Derek · Post by **Derek** » Fri Feb 06, 2015 7:33 pm

That's very clever, Gerald! Nice job!!!

Vipertech13 · Post by **Vipertech13** » Sat Feb 07, 2015 6:21 am

Thanks Tony and Derek! Yep, batteries grounds Taken care of. I went with flaperons to save some weight. I am really cutting it close on power here. The accepted normal power guideline is 100 watts per pound and combined I have 200 watts so 2 lbs would be about the max. I am currently at 28.4 oz. AUW. I did a redneck thrust test, put my scale vertical against the wall and put the plane's nose against it and ran the motors up to full power and she hit 29.4 oz on the scale so I think it will work! I wanted to do a few more test runs but my wife was upset because she could not hear the tv in the bed room over the roar of the motors. I want to do a amp draw test and shoot a video of it. May be she will go shopping tomorrow and I can get that done.

Vipertech13 · Post by **Vipertech13** » Wed Jul 08, 2015 3:49 am

Well moderators you can kill this build thread! This turkey just would not fly! I attempted three times and all I was able to do was get it about 6 feet in the air and stall it back to the ground. The motors just did not have enough oomph to maintain, no, achieve flight! It is dead! I will try a twin again when I get more funds for BIG motors.

Post by **danhampson** » Sun Jul 12, 2015 2:29 pm

thats a shame Gerald it another amazing looking plane you've built.

RC-Hangout

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Now back to the twin!

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Update DEAD BIRD!

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