Bird Shaped Flyer... ready for first flight!

[CactusJackSlade]

HERE IS THE BETTER THREAD ON THIS:

http://www.rcgroups.com/forums/showthread.php?s=&threadid=171945


Well,

Here it is, all ready for a maiden flight.

I did not cover the fuse or tail because I have a feeling that the tail configuration will change. The wings came out great.

I have it set up for full span adjustable camber as well as crow mixing for landing. If the elevator control is not too wierd (because of my design) it should fly! I suppose that I'd better hope I calculated the CG at least close??!


Wingspan: 92.5"
Length: 41"
Current built weight: 38 oz.
I have not calculated the wing area after butchering my OverKill cores so I don't yet.

I added 3.5 oz to get my theoretical CG point.

Anyway, here are some photos, I will give a flight report... tomorrow??!

[CactusJackSlade]

Here is a top view, I like the shape!

CJS

[CactusJackSlade]

Oh,

Here is the website link for a photo build up tour...

http://www.foaminfusion.com/EppTechHawk.html

CJS

[Daemon]

Looks cool.

With that span to length ratio though, I'd be worried about yaw stability. I doubt the tiplets will do much for directional stability (although they may help over efficiency). Gotta think you're going to end up having to use a fairly large V-tail to get the mix of directional stability and elevator control you need.

ian

[CactusJackSlade]

ian,

Yes I think you will probably be right, but I thought I'd carry out my first vision of this design to see what happens...

I am thinking of a V tail with a very shallow angle, like 80 degrees. This would add more yaw stability and rudder like control (if I added another servo) and since the fuse is so short pitch control is already sensitive enough... what do you (or anybody) think?

Although I might just make it into a flying wing as well. My big reason for a tail of any kind was for pitch control while using crow mixing for landing... I did also think about just a flying wing set-up with a vertical fin, like a Moth or Bandit.

Oh, sorry, no test flight today... wind was 30-35 mph with a peak gust today of over 60!

Maybe tomorrow!

CJS

[AustinTatious]

Hey, why not jsut add a little CLEAR fin on the bottom of the Fuse? Purposful and candid ... sort of :-P

[CactusJackSlade]

First of all, thanks for all the suggestions!

I had my first flight a few days ago and as I suspected the tail I built made it WAY too pitch sensitive... but after I got it trimmed it flew pretty good.

Only problem was if I even touched the elevator it would loop or dive! I did get one pretty good level flight after a lot of trim work and DID NOT TOUCH the elevator... it cruised right along. All these were just hand tosses.

I have already built a quickie coroplast tail... much more conventional with a fixed forward area and hinged aft area. I may still make a V tail, but I will see how this does first... also I may add a fin (like a moth/bandit etc) and make it a flying wing after I figure out the CG.

Speaking of CG I think it is going to end up WAY forward of what I calculated!

Anyway, hopefully another flight test tomorrow, weather permitting.

Anyway, here is a photo of my quicky Coroplast tail... I didn't even bother to feather the trailing edge until I see what it's going to do...

[CactusJackSlade]

Here is the underside of the tail, simple set-up. Just cut out a rib section on one side and you've made a hinge. Nice for prototyping... took me about 5 minutes to make this one.

To temporarily install it, I just slotted it in two spots either side of the fuse and used 1/2" strapping tape to secure it. It is actually pretty solid!

Test flight will tell all!

CJS

[CactusJackSlade]

Well the new tail did the trick... although still SUPER sensitive to pitch... but managable.

Man does this thing FLOAT?! Everytime I gave it some up to flare the landing it would just pop up and keep going! This should be a nice slow stable platform to anchor my wireless video stuff to!

Probably the one thing I need to work on is yaw control.

Daemon! Just what you said, I think the winglets are too close to the yaw axis and do very little. I think you are spot on when you say a large V tail will be needed to overcome the yaw issues of this lumbering wing!

Now that I have the CG pegged I may just try the flying wing configuration and add a vertical fin... the experiment continues!

CJS

[Daemon]

Another approach would be to put a vertical stab out back, either clear, or colored sky blue, or some sort of blue/white combo (camouflaged).

ian

[CactusJackSlade]

Ian,

Thanks for the comments. You have been spot on so far!

I think than rather than try to camoflage a tail I will probably just go with a sharp angle (90 degree or even less) V tail and just incorperate it into the overall design... I think a V tail would look cool anyway, and may be the function I need.

I am thinking that a high angle V tail will give me maximum rudder advantage with a decreased/dampened pitch control. The pitch is so sensitive with the short fuse that I think I need a more vertical V tail. This would help with the yaw issue as well. I plan to mix in rudder in conjunction with the ailerons, as well as a fair amount of aileron differential.

Anyway... more work ahead! Add a servo... design the V tail mount etc...

Here is me with the beast so far! If conditions were soarable I'd fly it as is for now!

CJS

[stegre]

Any more progress on this one, it sure looks cool ? A smaller one might be a cool sloper.

Steve
http://www.californiasailplanes.com

[CactusJackSlade]

Hey Steve,

Well, I've changed out the flat tail for a V tail and the yaw issue is pretty much solved, I added a rudder servo for the V tail so I could also mix rudder/aileron to help with yaw.

I have test tossed it, but the weather here has been most uncooperative... still waiting for that south wind to toss it from a hill! If I do not get some good weather (wind) soon I will get my tow hook set up and hi-start it!

Here is a current photo:

I'll definitly post a report when I get some flight time in!