|Feb 05, 2011, 03:45 AM|
Joined Jun 2008
SHARK DLG - Triangular boom, Y tail, low mounted wing
We thought we would post some information about our new DLG that we are developing called the Shark. It has a few unique features and most importantly it looks really different. It is the brainchild of Marcus Stent, Brad Wilman and Andy Smith and we are based here in Melbourne, Australia.
The heart of the design is in the triangular shape boom.
The trianglular shape is good for a few reasons:
1. The bottom of the triangle gives us a flat surface in the direction we need it (laterally) so we can build a mini I beam along the bottom of the fuz, which will be lighter and heaps stiffer than a round boom (refer theory on post #22. Construction on post #53. First Boom on post #81).
2. Traingular tubes can be made torsionally stiffer than round tubes (refer explanation on post #22).
3. It looks good and the extra stiffness results in a better launch height.
The (inverted) Y tail feathers.
This does a few things other than look cool:
1.We used Drella's V Tail sizing formula on the Elevators and Lower Fin, so we should be getting the same effective tail control as a conventional layout (refer explanation on post #26).
2. The Y tail will be set up with a fixed upper Fin and moving Rudder/Elevator control on the inverted V, so it still uses two servo's.
3.For Rudder control we only have the lower half moving and therefore the design is halfway beetween current trend of 'no Rudder' and 'full Rudder' designs.
4. The secret aerodynamic benefit is that when you deflect the surfaces for Rudder you get a 'proverse roll' effect. This means it is trying to roll the plane into the turn when Rudder is applied, where as conventional V tails try and roll you out of the turn when they are deflected.
The low mounted wing
This is not a new concept but a worthwhile feature for two reasons:
1. It does move the centre of mass higher and keeps the wing flatter during launch.
2. It fits on the Triangular boom better and adds to the unique look of the plane.
The other design philosophies are kept similar to the successful Salpeter, but we couldn't just make another cookie-cutter!
As you can see in the pic's the CAD is finished and we have also finished cutting the plugs for the wing moulds, so we are off and running...just got to keep running now!
Oh, and as for the name 'Shark'....we think it is self explanitory.
|Feb 05, 2011, 05:10 AM|
Looks great Marcus.
What sort of lay-up?
Spread-tow? Disser? 31 Rohacell?
1 piece fuz or pod/boom?
Inverted servos all in pod secured to the fuselage sides wth top-driven flapperons?
|Feb 05, 2011, 05:42 AM|
Great project but I must question this point.. Assuming a equilateral triangle where the leg length is the same as the diameter of the round tube (which would result in near enough same weight as a round tube).. then the round tube will be stiffer in torsion.. 25% stiffer to be exact.
|Feb 05, 2011, 09:18 AM|
Boy you guys must like to be different. I generally like the look of it and hope it does well for you guys.
Wing moulds suggest production????
|Feb 05, 2011, 12:53 PM|
United States, MD, Lusby
Joined Nov 2003
Very interesting design concept. No matter how it flies it will for sure be unique! Hopefully launch height is increased with the increased vertical area, although I'm a bit concerned with elevator effectiveness.
Have you run a detailed controls analysis?
I'm no structural expert (really only know what I'm talking about when it comes to controls and I can understand most aero discussions), but I'm not sure the triangle is really that much better than a round boom, although it would let you keep the same shape from nose to tail. Seems difficult to manufacturer well with stress concentrations in the corners.
I may have to actually fully design one of these blasted DLG's from the ground up one day, I have the tools and knowledge to do it, just lack the time.
|Feb 05, 2011, 03:24 PM|
Cool concept! Is there an aerodynamic reason for having the Y fins upside down? If not, a single, fixed fin pointing down (upright Y) would be less likely to be damaged in a rough landing, and easier to repair when the inevitable occurs.
|Feb 05, 2011, 10:43 PM|
|Category||Thread||Thread Starter||Forum||Replies||Last Post|
|Help!||Wing Dragon 4 tail boom replacement||Todd D||Foamies (Kits)||6||Dec 26, 2010 09:00 AM|
|Protecting a tail boom mounted servo||AaronOM||Fuel Heli Talk||6||Oct 13, 2004 01:10 PM|
|Yippee!||Aerohawk electronics mounted underneath the tail boom.||Fragster2001||Micro Helis||2||Jul 21, 2004 10:05 PM|