SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Feb 05, 2011, 02:45 AM
Aussie F3K Pilot
Melbourne, Australia
Joined Jun 2008
525 Posts
Cool
SHARK DLG - Triangular boom, Y tail, low mounted wing

Hi all,
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.

Cheers,
Marcus
Machineman is offline Find More Posts by Machineman
Last edited by Machineman; Feb 20, 2011 at 03:07 AM. Reason: clarification
Reply With Quote
Sign up now
to remove ads between posts
Old Feb 05, 2011, 03:52 AM
flying is not a dream
lebenj's Avatar
Spain, CT, Cardedeu
Joined Jan 2008
987 Posts
i really like your concept....
lebenj is offline Find More Posts by lebenj
Reply With Quote
Old Feb 05, 2011, 03:54 AM
Registered User
Joined Sep 2009
5 Posts
send me one to test if you like..
JOHNinCHCH is offline Find More Posts by JOHNinCHCH
Reply With Quote
Old Feb 05, 2011, 04:10 AM
Thermal Wrangler
DrFragnasty's Avatar
Launceston Tasmania
Joined Mar 2004
2,095 Posts
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?



Chris.
DrFragnasty is offline Find More Posts by DrFragnasty
Reply With Quote
Old Feb 05, 2011, 04:42 AM
Grumpy old git.. Who me?
JetPlaneFlyer's Avatar
Aberdeen
Joined Mar 2006
11,603 Posts
Quote:
Originally Posted by Machineman View Post
2. Traingular tubes are torsionally stiffer than round tubes.

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.
JetPlaneFlyer is offline Find More Posts by JetPlaneFlyer
Reply With Quote
Old Feb 05, 2011, 07:00 AM
Registered User
Joined Apr 2004
132 Posts
Marcus,
That looks pretty interesting....when do you plan to have a flying prototype finished?
6cuda6 is offline Find More Posts by 6cuda6
Reply With Quote
Old Feb 05, 2011, 08:18 AM
Now fortified with carbon
DLGjunkyard's Avatar
Canada, ON, Puslinch
Joined Apr 2010
2,718 Posts
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????
DLGjunkyard is offline Find More Posts by DLGjunkyard
Reply With Quote
Old Feb 05, 2011, 09:01 AM
Kyle Clayton
Wave Glider's Avatar
United States, VA, Dinwiddie
Joined Feb 2008
2,396 Posts
very cool, I'm anxious to see what the finished product looks like! What airfoil will you guys be using?
Wave Glider is offline Find More Posts by Wave Glider
RCG Plus Member
Latest blog entry: Helios and XXLite DLG
Reply With Quote
Old Feb 05, 2011, 11:53 AM
Aurora Builder
United States, MD, Lusby
Joined Nov 2003
3,437 Posts
Marcus,

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.
samc99us is offline Find More Posts by samc99us
Reply With Quote
Old Feb 05, 2011, 12:33 PM
Team Hong Kong F3K
ThomasLee's Avatar
Hong Kong
Joined Sep 2010
3,073 Posts
sweeeeet!
Can't wait to see the progress, should be sweet in the air.
I actually saw an inverted-Y tail group on one of the DLGs in the eurotour... wonder how they did?
ThomasLee is online now Find More Posts by ThomasLee
RCG Plus Member
Latest blog entry: Neos Layups
Reply With Quote
Old Feb 05, 2011, 12:40 PM
Registered User
Joined Sep 2007
284 Posts
the looks are very nice, but how do you put servos in this glider, triangles are usually used for the arms of the servo, but here, the wing is the way for both stab and ailerons, if in the fuse.

Cedric,
ced_toulouse is offline Find More Posts by ced_toulouse
RCG Plus Member
Latest blog entry: Ojective: TAIWAN!!
Reply With Quote
Old Feb 05, 2011, 02:24 PM
The ground's the limit.
shawnc's Avatar
Boulder, CO Area
Joined Aug 2008
833 Posts
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.

Shawn
shawnc is offline Find More Posts by shawnc
Reply With Quote
Old Feb 05, 2011, 03:34 PM
mmmmm....BEER
Launceston, Tasmania
Joined Jan 2010
186 Posts
Hey Dude,

Almost looks good enough to eat. Be careful with it around Brad
Boagy is offline Find More Posts by Boagy
Reply With Quote
Old Feb 05, 2011, 08:55 PM
Aurora Builder
United States, MD, Lusby
Joined Nov 2003
3,437 Posts
Shawn,

The reasons were posted above that v-tails have not so great turning habits that the y-tail fixes.
samc99us is offline Find More Posts by samc99us
Reply With Quote
Old Feb 05, 2011, 09:43 PM
Turn down for what?
rdwoebke's Avatar
United States, IN, Indianapolis
Joined Feb 2004
14,853 Posts
Quote:
Originally Posted by Machineman View Post


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.
That proverse roll effect is pretty minimal. I wouldn't design the tail around solving just that issue. If it were a big issue then every regular non dog tail would suffer it too.


Ryan
rdwoebke is offline Find More Posts by rdwoebke
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Help! Wing Dragon 4 tail boom replacement Todd D Foamies (Kits) 6 Dec 26, 2010 08:00 AM
Protecting a tail boom mounted servo AaronOM Fuel Heli Talk 6 Oct 13, 2004 12:10 PM
Yippee! Aerohawk electronics mounted underneath the tail boom. Fragster2001 Micro Helis 2 Jul 21, 2004 09:05 PM