Initially this was to be a "winter project" but a weekend of bad weather brought this forward, however it may not be completed until after winter.
The idea started as a discussion on the flying field "what if...." extended the wings,....... two fuselages, two engines.....
I already had the plan for a small .25 sized profile, "Taco" from Paul Swaney. This had progressed from my fascination in flying profiles and owning a Mojo 60 already from the said Mr Swaney's stables hanger.
Then Just Engines ran a two for one engine deal so two .25s were ordered.
The first stage was to draft the extensions to the wing. With some slight deliberation the centre section was created to accommodate two props with a little space between.
I then set about preparing the parts. I was partly lucky in that Paul had provided the wing wibs.
I'm well into the project now so I'll progressively load the build,(if anyone's interested), over the next few nights.
The plan shows a 91/2" mid section extension
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Sounds like a really cool project... I'll be following this thread..

SUBSCRIBED.

Tacos kick *****

Dang, I was already thinking of that. You have to keep posting photos.

What engines are you using? I have a couple of Magnum .28s that individually run OK, but hardly ever keep running on a twin. We have had them on 3 different twins and can never count on a reliable flight. I had one of those on my Taco and it ran great. I also had an OS .25FX on the Taco and I'll get another one for a twin.

I did a twin fuselage Sky Raider Mach II and used 14" center line spacing. I figured 12" props max and 2 " clearance. It is an excellent flying plane. None of my twins is 3D, which is why I was thinking of a Taco, Burrito or Mojo twin.

I have also not had good luck with the Magnum .52XLS on a twin. Again, individually fine, but not very reliable with 2 of them. I have had good luck with the GMS .47s and OS .46AX on twins.

Having made the extra parts required. The instructions were downloaded from Paul's site.
Construction was relatively easy and quick.

The photos show the ribs and the sub rib construction.

The wing was easily constructed by building the right wing, left on the plan built inverted, with the addition of the centre section. When this was dry, fairly short time using cyno and having a "tea break", the structure was slid along and the remaining wing constructed.

In answer to the engines, the offer was for two GMS 25's which I know little about except reading the odd bit off the net. However I must say I was impressed when they fired up on the test bench with only a little priming and were fairly easy to adjust. I ran with 8.5 X 6 Bolly's.
If all goes well here are some further progress photos. With a little teaser taken tonight.

Can I have some bean dip with that double taco?

don't forget the fresh, home made salsa! cool project!

Praise enough from the master of projects
Thanks Mr Bigg.

Here's a few more progress shots. with a little construction detail
Had a delay due to running out of 1/16th sheet balsa but that's now remedied.

Picture one shows the centre section now covered, with space for four hatch positions. This is to allow me the luxury of "carefully positioning the servos.

Picture two shows the inclusion of tubing to feed the receiver cable through the wing

And the third photo the engine mount just hung around

Cool !! I almost missed this one.

Hi Ed
swup Swany
Mike, going to Nashbro?

Fus construction and progress photos
A slight deviation from the instruction with the use of carbon fibre tube instead of fibreglass tubing. Other than that construction followed the instruction manual.

On completion of both frames these were taped together and any "highs and lows" sanded out.

As expected when "scratch building" discrepancies do occur, check the joint to the wing. This required some "balsa bashing" to get a good close fit.

how did you figure out, how big, the center section of the wing needed to be?

The honest truth?
Well as I'm fitting two 25s the maximum prop is going to be 81/2 X 6 or 7 so 2 X 81/2" = 9" + a bit of clearance say 1/2" therefore say inside dimension 91/2".
As they Keep It Simple Stupid
Will it fly ?
Don't know but it's worth a try!

Some more progress photos and comments
A little "balsa bashing" was necessary to obtain a better fit to the wings.(A closer photo of the gap from the last set of photos)

With this achieved the upper fuselage was epoxied to the wing and the carbon rod was held in place with the masking tape and then cyno was run along the joint. (I've found that this is more than adequate to join carbon fibre to balsa).

The lower sections were then epoxied and cyno'd. And left to cure.

Man, you'll be finished in no time at the rate your going!

Unfortunately work gets in the way!
Also I've a tempremental OS 120 that requires some attention.
I have actually progressed a bit further and will load these up later during the week.

Thanks for the continued interest and I'm glad you're back to building.

back to building for a while- my daughter is getting married next weekend, so this week will be hectic![sm=spinnyeyes.gif]

Well with one thing and another computer time had been down but a slight chance for an interim update with some photos. These are best described as building the "flappy bits".
Picture one
This bit is in fact not a "Flappy bit" but an essential part of the construction process, the "stabiliser". Like the wing the centre section is also separated by a 91/2" inserted centre section.
picture two
This is the construction of the elevator, which is all one piece.
I've taken a bit of a gamble here and reduced the overall area. This is because I have assumed that with the increased centre section this may cause the elevator to be too effective. I can always build a larger elevator if necessary.
picture three
Rudder construction is fairly straight forward, times two.
Except where the proposed leading edge of the elevator passes through the rudder I have put some balsa braces as some "balsa bashing" in the shape of a cut out will have to be made in the rudder edge.[picture four]

I didn't take a picture of the ailerons!

johny,

the plane looks great, definetly an original.

So what type of flight are you hoping for? It should be a good acrobat but I would guess with 2 engines you take away most 3D ability?

I guess a harrier wouldnt be out of the question.

I'm not really sure what it's flight characteristics will be. So long as it flies, which I'm sure it will. Interesting to speculate. I "open the floor" to any suggestions. At the rate of build, due to more bad weather the maiden could be as short as three or so weeks away.

I would think you have plenty of vertical. The Taco was designed for a .25/.28. I have had both an OS .25FX and a Magnum .28 in mine and they were easily 3D capable. I have also build a twin fuselage plane and it has great performance. To a normal Taco you are add an extra fuselage and engine and a small center wing. This isn't double the weight, but you have twice the power. It's going to have tons of vertical.

If you use a computer radio, you can mix engine to rudder and have one engine cut back with rudder and should get great flat spins. Looks to me like a great project.

Knife edge should be good too!

I was thinking too that it will have a lot of power. Becuase you double the power but increase weight by only a half or so because you only have the weight of a small wing and the fuselage but dont add radio gear, full wing, landing gear, etc.

I bet you could have used 2 .15´s and still had good performance

I've finished the construction, well major "balsa bashing" so below is a Naked Double Taco

Looks great. You didn't think about a flap in the center? You don't need flaps, but you might use one in a crow set-up.

I would also think about holding elevator and rudder servo placement until you cover and install engines. You might need to move 1 to the rear for CG.

I found I needed something stronger than HS 81s on ailerons. They just weren't powerful enough.

On my twin fuselage Sky Raider, I used double servos-2 aileron, 2 elevator, 2 rudder, 2 throttle. You normally use 5 so this is 3 extra. I also split my elevator in the center and mixed to get them together a la dual elevator set-up.

Man, it sure would be something to 3D a profile twin. That is one sharp project.