HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Dec 03, 2010, 07:11 AM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
3,741 Posts
Charles
Quote:
Nick, didn't you change the front airfoil on your latest?
Yes, it's the flat bottomed thin one (8%) that I also used on the Long EZy and the EZyCat. This seems to give me a very gentle stall and a short recovery, just a nod in fact. I felt the need for something bigger with a longer moment than the Delta Duck to cope with the water-drag and the high thrust line this time.

Nick
nickchud is offline Find More Posts by nickchud
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 03, 2010, 09:57 AM
Registered User
Joined Jun 2005
2,465 Posts
Check this canard water plane out.

Large WISES model flying! (Japanese ekranoplan and WIG concept) 空飛ぶ船(大型模型) (1 min 22 sec)
canard addict is offline Find More Posts by canard addict
Reply With Quote
Old Dec 03, 2010, 10:15 AM
Registered User
Joined Jun 2005
2,465 Posts
The Ekranoplanes are interesting. Charles

Ekranoplane (8 min 51 sec)
canard addict is offline Find More Posts by canard addict
Reply With Quote
Old Dec 03, 2010, 01:10 PM
who has rabbit ears down
Captain Canardly's Avatar
United States, MN, Buffalo
Joined Jan 2007
3,634 Posts
Ahhh Bummer- I thought I had a "new Idea"- at least we can get our overseas LiPos in a hurry!
Thanks Charles!
Captain Canardly is offline Find More Posts by Captain Canardly
RCG Plus Member
Latest blog entry: One printer running!
Reply With Quote
Old Dec 03, 2010, 02:45 PM
Registered User
Joined Jun 2005
2,465 Posts
36 inch Delta Duck Wing

The second wing turned out really well. Unlike previous wings of high aspect ratio, it should not warp from covering or the environment. The spruce hardwood spars have great tensile and compressive strength. I estimated the model to weigh 3 ounces more than the original.
Charles
canard addict is offline Find More Posts by canard addict
Reply With Quote
Old Dec 04, 2010, 01:02 AM
Registered User
John235's Avatar
Sydney, Australia
Joined Mar 2006
1,315 Posts
Quote:
Originally Posted by canard addict View Post
John, This quote and your comment on the no bounce Duck landing limited my sleep to 3.5 hours with another 1.5 hours spent tossing and trying to analyze the models flight characteristics. Both airfoils are symmetrical and have zero lift without positive angle of attack. the main wing is at zero incidence, the canard is at 2 degrees and the motor's thrust line is at 2 degrees negative.
The landing from the video on page 318 left me very impressed. I'm not totally sure how much to attribute to the model versus your flying skills. I think its safe to say that both aspects are performing well. My comment was based on the reduction of pitching moment co-efficient when using a symmetrical or low-camber airfoil on the main wing. I wrote about that previously here. Lower negative pitching moment allows the canard to unload which will allows more elevator authority.
Quote:
Originally Posted by canard addict View Post
My head is spinning wondering if performance could be improved with a higher lifting canard airfoil with smaller area? Nick, didn't you change the front airfoil on your latest?
Charles
I think a well chosen flat-bottom airfoil on the canard would most likely perform better at low reynolds numbers and could even allow the stall speed to drop slightly - all else being equal. It would probably need less assistance from the elevons which would improve aerodynamic efficiency, although that's probably not a priority for this model. The delta duck flies so nicely that I can't really see a reason for changes. It would be a pity to risk any change to the aerobatic capabilities of this model. Looking at your CG calculation above, the canard area is only 11% of the newly updated main wing. It seems already small enough, especially since the tip chord is only 2.8". If considering reynolds numbers, I can't imagine there is much to gain from reducing the dimensions any further.
John235 is offline Find More Posts by John235
Reply With Quote
Old Dec 04, 2010, 01:09 AM
Registered User
John235's Avatar
Sydney, Australia
Joined Mar 2006
1,315 Posts
Chalres, thats and awesome looking wing structure you posted. The build precision looks amazing!
John235 is offline Find More Posts by John235
Reply With Quote
Old Dec 04, 2010, 10:30 AM
Visitor from Reality
United States, VA, Arlington
Joined Dec 1996
12,788 Posts
Hi Charles
Ekranoplanes - amazing widgets indeed.

They were always cropping up in the darker corners of my old day job, around the mid-1980s. The best part was that none of the intel folk could figure out what they were for!

Basically, they could operate over water that was pretty much flat. Large waves 'grounded' them. Overland operation might have been possible in the flat parts in the middle of Russia, but not only was that dubious and how could they have got there to start with - bu why? was the main question. Some thought they may be aimed at troop transport for amphibious landings, except the USSR had plenty of shipping capability to do that in the event of, say, WW3

Cheap research it wasn't. That 8 jet monster in your video posting probably cost as much as a new frigate, which could attack shipping and / or detect and chase submarines - little of which that WIG monster could have done.

Though models of it would be fun to mess with if you're into that sort of modelling, and that Japanese one would be handy for rich folk whose bank accounts are so overstuffed that they had to spend a few hundred thousand

BTW - lovely bit of wing construction there. A full sheet D box is, IMO, the best way to start any wing you'd like to remain stable and warp-free for the duration. Though all my designs seem to have parallel chord wings for some reason that escapes me. It's either an aerodynamical reason I can't spell, or laziness

D
Dereck is offline Find More Posts by Dereck
Reply With Quote
Old Dec 04, 2010, 12:26 PM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
3,741 Posts
Dereck
Quote:
BTW - lovely bit of wing construction there. A full sheet D box is, IMO, the best way to start any wing you'd like to remain stable and warp-free for the duration.
Couldn't agree more!

If you were half as destructive as me you would put webbing between the spars all the way across, just has you have done in the centre section. I find my wings outlast my fuselages several times over. That Delta Duck wing is now on its third incarnation. It's very robust. Mine is looking a little battered, complete with doggy toothmarks, but it's still giving me a lot of fun.

I'm looking forward to seeing your Mark II Duck.

Cheers

Nick

BTW How does that Japanese Ekranoplane get its propulsion? I can't see any props. Are there EDFs expelling through the trailing edges? What have I missed?
nickchud is offline Find More Posts by nickchud
Reply With Quote
Old Dec 04, 2010, 12:33 PM
Registered User
Joined Jun 2005
2,465 Posts
John 235
Quote:
think a well chosen flat-bottom airfoil on the canard would most likely perform better at low reynolds numbers and could even allow the stall speed to drop slightly - all else being equal. It would probably need less assistance from the elevons which would improve aerodynamic efficiency, although that's probably not a priority for this model. The delta duck flies so nicely that I can't really see a reason for changes. It would be a pity to risk any change to the aerobatic capabilities of this model. Looking at your CG calculation above, the canard area is only 11% of the newly updated main wing. It seems already small enough, especially since the tip chord is only 2.8". If considering reynolds numbers, I can't imagine there is much to gain from reducing the dimensions any further.
John, Thanks for your kind support and observations. Your thoughts make good sense to me and are thought provoking.

The D. Duck 2 will use the same same canard wing and being only 11% of the main, may hold down the climb rate at full throttle. The big delta wing seems to be highly sensitive to CG changes. A Mark 3 version may have a flat bottom canard at zero incidence relative to the bottom and a vertical tail assembly with it's leading edge at ailerons TE. What could go wrong with those changes on a proven good flier? I have not tried inverted flight again with the added 2 degrees down thrust which will become up thrust and may relieve the forward pressure I needed on the elevator control. My big question is: will the new wing experience a tip stall in high speed turns?

Dereck, thank you for responding with your views on the Ekranoplans. I did not check out the meaning of the word but trust that your RAF days gave you insight. I still feel that my wing cross section design had it's start from one of yours in a publication. Do you still have that view handy? It does not require those miserable slots which I always hated because they could not be cut with any accuracy.
Charles
canard addict is offline Find More Posts by canard addict
Reply With Quote
Old Dec 04, 2010, 12:57 PM
Registered User
Joined Jun 2005
2,465 Posts
Nickchud
Quote:
That Delta Duck wing is now on its third incarnation. It's very robust. Mine is looking a little battered, complete with doggy toothmarks, but it's still giving me a lot of fun.
I'm glad you are enjoying it, Nick. I could not help sharing the new build because it gave me the most satisfaction ever! The webs will make it extremely tough but since there will be negligible shear on a 10 ounce loading, I figure like Dereck, laziness rules.
Charles
canard addict is offline Find More Posts by canard addict
Reply With Quote
Old Dec 05, 2010, 12:56 PM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
3,741 Posts
Polar Duck Video

Sorry, not a very good video. Wrong camera and we ran out of time before lunch. Still, you get the idea. There were some good rolls and loops in there, but too far away unfortunately. I'm not good enough to do that stuff close to the ground.
PolarDuck1.wmv (1 min 50 sec)

The plane survived the dog attack, no harm done. He's not as fierce as the video makes him seem.


Now here's an interesting canard experiment....
Crazy Science: Aileron Canard or Ailenard ?? (3 min 6 sec)

I tried a canard idea for the Stuntcat, but I went for an elevator, not ailerons.

Never thought of that! There's always another idea out there!
nickchud is offline Find More Posts by nickchud
Last edited by nickchud; Dec 05, 2010 at 01:10 PM.
Reply With Quote
Old Dec 05, 2010, 01:15 PM
Jets are for kids-of all ages
Florida, USA
Joined Jun 2008
2,892 Posts
And here is why I will never have another depron plane. I make a lot of planes out of Elmers Foam Board and while somewhat heavy, it is extremely strong. So from now on that is my medium.


The story is it was flying fine but it was windy on Saturday and a cross wind at that. Coming in for a landing the wind pitched it up, but adding power to get some forward airspeed to get the nose down, it was blown toward the spectator area, so I purposely nose it into the ground to protect anyone from getting hurt. Depron NOT DO LIKE asphalt.

Roger
mullinspsm is offline Find More Posts by mullinspsm
Last edited by mullinspsm; May 12, 2011 at 06:57 PM.
Reply With Quote
Old Dec 05, 2010, 03:41 PM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
3,741 Posts
Ouch! Roger, what a shame!

Don't be too hard on the Depron, I got pretty much the same result with my balsa Long Ezy.

If you see that Stuntcat in the video above, I've got one like that and I lent it to a visiting 6 year old boy this afternoon, I've also lent it to my daughter's boyfriend, my neighbour, who's a beginner and however old he is, it's more than me. I get airborn first and then hand them the Tx. It's been stuck up trees and crashed so many times that the glue and tape pro'ly weighs more than the Depron. Still it keeps on going and flies straight as an arrow, good enough that I can catch it one handed every time.

On the other hand, there's nothing so satisfying as building with balsa and film. I just wouldn't lend those planes to those people.
nickchud is offline Find More Posts by nickchud
Reply With Quote
Old Dec 05, 2010, 04:23 PM
Registered User
Joined Jun 2005
2,465 Posts
Future Delta Duck?
Charles

RC Canard Experimental Plane (with gyros) (1 min 15 sec)
canard addict is offline Find More Posts by canard addict
Reply With Quote
Reply


Thread Tools