80" B26 Marauder

[awrightbrother]

This is my first thread at Flying Giants.

I had designed, built, flown, and kitted a 60" version of a B26 Marauder, a few months ago. Details and flight video of this model are at http://www.wowplanes.com/product_inf...roducts_id=116

This one turned out to be such a good flyer that I have received several requests for an 80" version. In this thread, I will walk through the design, building, and flying phases of this model. After that I plan to make it available as a kit.

The pictures below show what comes out of the kit box, and how it will end up looking when finished. This is the 60" version, and the 80" one will look similar with a few changes. This particular one is going to be electric powered, but my kits lend themselves equally to gas power.
Please feel free to give me your input and feedback on the construction technique. So lets get started.

Regards
Fahim

[awrightbrother]

Having sent away the plastic plugs for fabrication, and a few honey do's out of the way, I started earnestly on the build this morning.

Since I am also building the construction manual for this kit, I will use the same pictures. The text within the picture explains the context.

The basic fuselage structure is done except for shaping the nose block. I have to defer this until I get the nose gunner and canopy plastic back from my supplier. Then I can check for fit while shaping. Meanwhile I can work on the tail and wings next.

At this point the fuselage weight is just under 1 lb 5 oz. I expect it will come in around 2 lbs when finished.

If you have any questions, please feel free to ask.

Fahim

[awrightbrother]

I worked on the Fin & Rudder this morning.

The text in the pictures explains the steps.

I like to keep things simple, but this is not the only way it can be done. If the servo is to be hidden inside the fuselage then, the servo pocket foam plug can be glued in place to fill the cutout. If more scale like hinges are to be used then the rudder hinge face can be done differently. Lots of flexibility and room for creativity and innovation.

On with the horizontal stab next.
Fahim

[SleepyC]

Wow.. cool. All foam?

[awrightbrother]

	Quote: Originally Posted by SleepyC
	Wow.. cool. All foam?

Thanks SleepyC,

This is not going to look, feel, smell, or behave, anything like foam when we get to the surface finishing stage. Stay tuned.

Fahim

[awrightbrother]

I worked on the horizontal stab and elevators this afternoon. Here are pics of the step-by-step assembly.

The weight of the tail feathers up to this point is 5.1 oz. So we are up to 1 lb 10 oz at this point for the fuselage and tail.

I plan on using one servo per elevator imbedded in the stab. Again, I should mention that this is not the only way to do this. A single servo can be hidden inside the fuselage and the hinges can be different. That's all left to individual builder's preferences.

Next come the wings and nacelles. Lot more work there.

Fahim

[awrightbrother]

Started work on the wings. Got the wing panels prep'ed. I don't plan to have flaps on this build, but it is a simple matter of using the 3 view provided in the manual to measure, mark, and cut out the flaps if desired.

Note that the kit will include the wing beds to help those who want to balsa sheet the wings. It also helps me keep my garbage collectors happy.

The next step would be to join the wing panels and install the spars.

Fahim

[Trumpetman]

Interesting! What is your projected all up flying weight? I'll be interested to see where the strength comes from to support an 80" foam airplane.

[awrightbrother]

	Quote: Originally Posted by Trumpetman
	Interesting! What is your projected all up flying weight? I'll be interested to see where the strength comes from to support an 80" foam airplane.

Trumpetman,
My guesstimate at this stage is for an AUW between 10 & 15 lbs. I will have a better handle on that as the build progresses further. I plan to have three 1/4" plywood spars, two that go just past the nacelles and one that will go all the way to the wing tips. Then I plan to cover it with several coats of Liquid Sheet which will give it added strength. I don't know if all this will be enough, but the only way to find out is to do it.

If, heaven forbid, we find that it is not enough, not all is lost. I can build a second plane within a few days and build it stronger with balsa sheet + Liquid Sheet. That I am sure will be very strong, albeit heavier.

Any help/suggestions/observations/comments, positive or negative, are greatly appreciated.

Fahim

[awrightbrother]

I got the wing done and will let the joints cure overnight.

The wing has two 1" x 1/4" plywood spars and one 3/4" x 1/4" plywood spar. The mid spar goes all the way to the tips, while the two outter stars go just past the nacelles. The nacelles have the better part of the weight of this planes i.e. the motors & retracts, so extra support there is in order I think.

Here are some pictures.

Fahim

[JohnVH]

nice, subscribing!

[awrightbrother]

Worked on the wing mount.

The wing is held in place by two 5/16" dowels in front and two 1/4" screws at the rear. The wing is essentially done at this point. Next would be the nacelles.

Here are some pics.

Fahim

[awrightbrother]

The first plastics set arrived yesterday and I was able to finish the fuselage that I had suspended earlier. Here is a picture of the assembled frame without the nacelles. The tail feathers are not permanently attached yet, just taped in place for the picture.

I will be working on the nacelles next.

[awrightbrother]

I worked on the nacelles and cowls today. Could not finish it all because the retracts have not arrived as yet.

My build is for electric power, but once the firewalls are in place, a gas or nitro installation is easy to visualize.

Here are some pictures of my progress.

Fahim

[awrightbrother]

I wanted to see how strong the wing is. I put a 39 lb cinder block on it and it held up. Now that's bare foam and plywood spars. With LS applied, it would easily go up to 50+ lbs. With a 13 lb AUW, that is 4G. I am more than happy.

I did not want to keep adding weight until it broke, but at 4G it is more than enough for me.