Living room flyer help

[j8m8l]

Hi

I am a high school student studying Design & Technology for my A-level's. For the project this year, I am building a Living room flyer, a plane which can be flown in a small living room. I have built most of the control system, which is based on this (http://www.rcgroups.com/forums/showthread.php?s=&threadid=24711&highlight=diy+ir) thread.

The plan is for a monoplane, built mainly from carbon fibre (covered in 2gsm mylar), using modular design, and magnets to hold together many parts (so that in a crash, they will "pop" apart). At present I plan a 56cm span, 18cm chord wing, with a design similar to the Kolibri (but with ribs). This will have an area of around 930cm^2, and with an estimated RTF mass of 9g, a wing loading of 0.96 g/dm^2. I am thinking of a v-tail design similar to didel's (http://www.didel.com) living room flyer, with a total area (not including the rudder) of 160cm^2 (17% wing area).
http://www.btinternet.com/~l.levine/img/vtail.jpg
Does this design (and area) look ok?

I require some assistance with estimating the flight speed, Cl, and fuselage length, can you guys help?

Below are a couple of images showing the wing ribs, and a wing half.
http://www.btinternet.com/~l.levine/img/ribs.jpg
http://www.btinternet.com/~l.levine/img/wingribs.jpg

Thanks
Josh Levine

[AndyOne]

Josh,

There was a graph of wing loading against feasible room size posted in the indoor and micro section about a year ago, I did a quick search but I can't find it. I think Gordon Johnson may have posted it.
I think the graph also had data on flying speed.

As far as the CG is concerned, if you put it at 30% of the wing area back from the leading edge you can't go far wrong.

Andy.

[j8m8l]

Thanks Andy.

Was it this graph?
http://www.rcmicroflight.com/dec99/images/model_weight.jpg
Found on the sample article section of rcmicroflight.

That estimates a room 5m long, just what I am aiming for.

Josh

[AndyOne]

Josh,

Looks like the one.

Andy.

[JohnHorn]

What airfoil is it, or just something from scratch? I have extensive airfoil tables and can give you all the data for whatever foil you are using. Or find something similar if it is a homemade foil.

[opualuan]

given the weight/wingloading constraints, I would skip the ribs... you can't afford ANY unnecessary weight. kolibri's seem to fly fine with the wingtip-induced airfoil shaping to the covering... at these speeds I doubt an accurate airfoil is that important...

[j8m8l]

Thanks Guys.

JohnHorn - The airfoil is the upper surface of a Clark Y. The wing will only be covered on the top. If you could get me some data it would be very helpful !

opualuan - I have thought of a Kolibri style wing. This would be best weight wise. I am planning on having two joining wing halfs, since transport would be very difficult with such a large fragile wing. I was hoping to avoid dihederal threads, using the weight of the body, to pull in dihederal (the wing is rather flexable). This would make using the wing tip shape for airfoil difficult.

How can I estimate a suitable fuz length, and what sorta of area should the tail surfaces have? Any help would be great... I am running out of time to get this built !!

Thanks
Josh.

[Ollie]

I'd use these guidelines for sizing the tail area and moment arm by Dr. Mark Drela:

"Ch = (A_hori/A_wing) * (tail_arm/avg_wing_chord)
Cv = (A_vert/A_wing) * (tail_arm/avg_wing_span )

A well-sized tail will be in the range...
Ch = 0.35 - 0.50
Cv = 0.02 - 0.035
If the Ch and/or Cv are below the minimum values, the handling will suffer."

Use the longest tail moment arm that will allow CG placement without extra nose weight and tail areas to meet the minimum Ch and Cv criteria.