Project Bird Monster

[Rob Nicholson]

Alright, I am in the middle of a Dynaflight Bird of Time build. But, I am taking an AME course, and after talking to one of my instructors I found out he enjoys building rc helicopters. He's also instructing the composites section of the course and, after a bit of talking, gave me permission to build something in the composite lab with any of the materials there. I jokingly suggested a spar and fuselage for a 6 meter wingspan sailplane, and he said go for it. :eek:

I'm a bit out of my league now, but I've been researching for the last couple of weeks, and I'm going with 2x scale Bird of Time. Reasoning: I already have the plans, and current experiance with the model. I've always liked this model, and I'm hoping this might be the biggest one around. I only have experiance with wooden build ups, so I beleive a carbon spar and d-box will leave me with the shallowest learning curve.

I am starting with the fuselage, carving a plug from insulation foam. We will be using what he calls the lost mold technique to make the fuse. I read a web page where someone did this with carbon sleeve, dissolving the foam core afterwards with solvent. We'll be pretty much copying this technique.

Don't have a concrete plan for the wing structure yet. Other then it's going to be a three peice, with the same planform as the original BoT, but probably a newer airfoil, still doing the research for that, any advice would be great.
Ailerons? Do you think it's silly to go without them one something this big? Or would you keep it original.

What I have so far, as you can see in the pic, is the fuse plug carved out on the side view, hope to get the top view carved out tomorrow, and then the final shaping. I extended the length of the rear fuse area as the rudder response was pretty much the most commen complaint I found about the design. I'm going with a just slightly sleeker then the BoT fuse footprint, I never liked the look of skinny uniform tail booms. Oh yeah, I got the plans blown up 200% at a local print shop for just over 10 bucks.

Anyhow, I plan on documenting this thing, and I have to get it done before the end of the school year. So I guess I should get back to work.

More soon.

[Alex J]

Interesting! :cool:

For a possible wing structure, take a look at the Allegro Lite or Bubble Dancer designed by Mark Drela.

http://www.charlesriverrc.org/articles/allegrolite2m/markdrela_allegrolite2m.htm

http://www4.ncsu.edu/~djedward/planes/bubbledancer/bubbledancer.html#cent

http://www4.ncsu.edu/~acstewar/BD.html

Or at the Houston Hawk, designed by Jack Womack.

http://www.rcgroups.com/forums/showthread.php?t=157276

http://www.houstonhawks.org/Projects/HoustonHawk/OverView/HoustonHawkProject.htm


I've built both the Allegro and the Houston Hawks and not having flawn the Hawk yet, both have very strong wing structures.

And being no expert, for better rudder response I'd rather enlarge the rudder and fin area than lengthen the arm. You don't want more weight in the tail.

http://www.charlesriverrc.org/articles/kitmods/dickwilliamson_gpspiritmods.htm

Check what he has to say about another planes fin and rudder area.

Keep posting!

Alex

[Ollie]

The braided sleeve carbon is very costly. Carbon costs are going up. See:
http://store.friddles.com/browse.cfm/4,2192.htm

I suggest you skinny down the front of the fuselage. The sleeve dia. has a maximum and a minimum. You might want to cut down the fin height to fit the sleeve, also.

See:
http://www.favonius.com/soaring/lost_foam/lost_foam.htm
"You can even use off-cuts or pieces of glass fibre, Kevlar or carbon fibre cloth if you can't get braid."