News:



  • May 12, 2024, 09:48:06 PM

Login with username, password and session length

Author Topic: canard concept  (Read 1146 times)

Offline jim gilmore

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1216
canard concept
« on: September 01, 2010, 03:23:11 PM »
Ok, here is my idea as a canard concept. It may get built but I have too much stuff going on that may prevent me from any real building. There might be many changes but first off 1/2a is the best place for me since I'm very limited on space.

Offline Tim Wescott

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 12818
Re: canard concept
« Reply #1 on: September 01, 2010, 04:12:34 PM »
Twin?

The basic layout is that of the Sarpoulis "Wild Goose", although your aesthetics are completely different.

Think what you could do with an electric, with the motor in back & battery up in front for proper balance.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline jim gilmore

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1216
Re: canard concept
« Reply #2 on: September 01, 2010, 04:25:08 PM »
I have searched for the wild goose but been unable to find a photo.
I know that looking at it leaves it a bit confusing if the model is a twin engine or a single with twin booms.
I was thinking twin boom with a center nacelle .
electric would easily make starting a  finger saver a least.
It does kind of resemble a bird.

Offline Tim Wescott

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 12818
Re: canard concept
« Reply #3 on: September 01, 2010, 05:20:28 PM »
I have searched for the wild goose but been unable to find a photo.
This thread, 6 posts down:
http://stunthanger.com/smf/index.php?topic=17629.0
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline PerttiMe

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1175
Re: canard concept
« Reply #4 on: September 02, 2010, 02:37:26 AM »
Flaps?

A canard might not need them. At least that is the impression I get when reading about other canard projects. It would save a little weight and complexity, too.
I built a Blue Pants as a kid. Wish I still had it. Might even learn to fly it.

Offline minnesotamodeler

  • 2014 Supporters
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2335
  • Me and my Chief Engineer
    • Minnesotamodeler
Re: canard concept
« Reply #5 on: September 02, 2010, 08:06:02 AM »
Seems the flaps would be counterproductive, trying to pitch the wing down as the elevator is trying to raise the nose...or, if coupled to move the same, it would decrease the wing's lift just when it needs more.  Just MHO. elevator-only (in front) works well.
--Ray 
Roseville MN (St. Paul suburb, Arctic Circle)
AMA902472

Offline john e. holliday

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 22776
Re: canard concept
« Reply #6 on: September 02, 2010, 09:26:04 AM »
I had forgot bout those picks of my Blue Goose I call it.  It is my version of the Sarpolous Wild goose.  I have the trailing edge flaps of the main wing moving very little.  Also the front moving surface has been cut down on movement.  Set up in the method shown it was a hand full.  It was a challenge I made to myself to build the plane.  Someone at the time stated that canards could not do the stunt pattern.  It may not do a competitive pattern, but it will do a reconizable pattern.  My problem is no flying it enough.   H^^
John E. "DOC" Holliday
10421 West 56th Terrace
Shawnee, KANSAS  66203
AMA 23530  Have fun as I have and I am still breaking a record.

Offline jim gilmore

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1216
Re: canard concept
« Reply #7 on: September 02, 2010, 03:44:20 PM »
Ok, do not shoot me here...some basic questions.
1. why do we use flaps in the first place?
2.  Even the B-2 has flaps and it has no conventional horizontal stab.
3. Does the flap increase lifT as speed drops? As in when you change direction. the lift is no longer in the direction the a/c was prior to the change in control surfaces movement. Not sure I'm explaineing what I mean clearly here.

Offline john e. holliday

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 22776
Re: canard concept
« Reply #8 on: September 02, 2010, 04:58:00 PM »
Is the B-2 a canard?   Maybe some of the experts will explain why we use flaps on stunt planes.  I have flown several stunt planes that did not even have flaps.   H^^
John E. "DOC" Holliday
10421 West 56th Terrace
Shawnee, KANSAS  66203
AMA 23530  Have fun as I have and I am still breaking a record.

Offline jim gilmore

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1216
Re: canard concept
« Reply #9 on: September 02, 2010, 05:59:40 PM »
No the b-2 is kust a wing. But still has flaps.
My understanding is that flaps are for when the speed slows and we need more lift .

Offline Tim Wescott

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 12818
Re: canard concept
« Reply #10 on: September 02, 2010, 06:02:59 PM »
Ok, do not shoot me here...some basic questions.
1. why do we use flaps in the first place?
My understanding, from lots of reading and very little plane building, is that it makes for a smoother looking square corner.  It's debatable whether they're actually necessary, as apparently folks can build flapless planes that corner square just fine -- except they don't look as good doing it.
Quote
2.  Even the B-2 has flaps and it has no conventional horizontal stab.
The "flaps" on the back end of a flying wing are the elevators.  High-lift devices on flying wings are restricted to leading edge slats, drooped leading edges, and maybe vortex generators (turbulators).
Quote
3. Does the flap increase lifT as speed drops? As in when you change direction. the lift is no longer in the direction the a/c was prior to the change in control surfaces movement. Not sure I'm explaineing what I mean clearly here.
A flapped wing will generate more lift before it stalls than an unflapped wing.  It'll also generate lots more drag.  I suspect that the biggest thing that flaps do for you in control line stunt is to lessen the need for extreme pitch angle on the square corners, and generating more lift is only the second-biggest thing.

Flaps also give you the opposite pitch moment than what you want -- drop the flap trailing edge and you not only generate more lift for a given pitch angle, but you also make a pitch down moment which has to be overcome by the elevator.  This leads, if I'm not mistaken, to the need for the relatively enormous horizontal surfaces on flapped stunters vs. just about everything else in all creation.
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Online Larry Renger

  • 21 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 4000
Re: canard concept
« Reply #11 on: September 03, 2010, 12:33:45 AM »
OK, here is my read on flaps.

1.  You change your angle of attack of the wing instantly as you deflect them, no fuselage motion required.  If you tune the flap/elevator ratio just right, the fuselage will flow through a corner with perfection, no plus or minus angle of attack.  The corner can look perfect.

2.  You can carry more weight, as the wing can generate more lift.  This makes a more "dense" model possible, and wind gust effects are reduced.

3.  The reverse pitch effect of deflecting flaps means you need more elevator movement than without flaps, and thus, the coorect sensitivity of controls is easier to achieve.  You can use more handle spacing, and finding center is easier.

4.  "Downwash" from the flaps actually helps the stabilizer generate its lift in the correct direction.  I haven't a clue whether this is good or bad.  Brett?  Help???

5.  Since it is usually easy to provide more power to a model, the added drag of flaps is of no significance.  The ultimate stunter would have infinite thrust and just under infinite drag.  No other forces would matter.  Speed would be constant, no matter what.
Think S.M.A.L.L. y'all and, it's all good, CL, FF and RC!

DesignMan
 BTW, Dracula Sucks!  A closed mouth gathers no feet!

Offline PerttiMe

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1175
Re: canard concept
« Reply #12 on: September 03, 2010, 06:16:34 AM »
OK, here is my read on flaps....
I believe those things apply very much to large ships of conventional design (although some seem to have done well without flaps).

In case of a 1/2A canard, some things are surely different.
- power is not all that abundant
- weight and drag may be more critical
- the elevator is in front of the wing. When you give an "up" control input, a conventional ship responds by moving its tail down, while a canard responds by moving its nose up.

... just armchair e-engineering here  :P ...
I built a Blue Pants as a kid. Wish I still had it. Might even learn to fly it.

Offline Serge_Krauss

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1330
Re: canard concept
« Reply #13 on: September 03, 2010, 09:52:29 AM »
Hey, guys-

'just perusing the board for the last times this week (early departure on vacation tomorrow). So I'm sorry not to be able to take some time for deeper comment. There are some very good (and also some marginal) comments here already, but at the risk of being a "cracked record" (LP - most of us remember these, and even 78's), I gotta comment again that there is an absolute wealth - treasure trove - of wisdom on this subject in the archives, especially on the older of these forums. The search function will doubtless prove very valuable on this topic. Try it!

For canards...I cannot see any good coming from "main-" (aft) wing flaps. They increase lift on a wing whose lift is not limited by its own configuration and area, but by the necessity of limiting its maximum lift to load the canard higher. This simply can come to no good, if the flaps on the main wing load the canard even more toward a stall! Neutral point and relative CLmaxs  are the canard story (see other posts). The higher the canard lift, the higher the wing lift, but the canard must reach its stall point first. 

SK

Offline jim gilmore

  • Trade Count: (0)
  • Admiral
  • ******
  • Posts: 1216
Re: canard concept
« Reply #14 on: September 03, 2010, 12:41:04 PM »
There are some things being said that are marginal and thats where the difference between the fact and subjective hit the wall.
Yes the stability of a canard is that the front wing will stall before the back wing. But flight for aerobatic's use thrust to overcome stall in the first place. A brick with enough thrust will still fly.
Yes I built the b-2 it has elevator and flaps, and rudders though not the way most people think of rudders. Plus aerolons.<sp>

Beyond that I cannot say a whole lot.

If the down wash from the flaps help the elevator do its job in normal flight. Does that mean when inverted it works against it ?
My understanding was that it modify's the airfoil creating more lift while the elevator turns/pivots the fuselage and the thrust pulls the plane along the path.
Simplified explanation here.



Offline Tim Wescott

  • 2016 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 12818
Re: canard concept
« Reply #15 on: September 03, 2010, 12:59:08 PM »
I thought this might be interesting:
http://www.djaerotech.com/dj_askjd/dj_questions/canard.html.

Better yet, here's your concept only with two engines:
http://en.wikipedia.org/wiki/Miles_M.39
« Last Edit: September 03, 2010, 01:20:27 PM by Tim Wescott »
AMA 64232

The problem with electric is that once you get the smoke generator and sound system installed, the plane is too heavy.

Offline minnesotamodeler

  • 2014 Supporters
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2335
  • Me and my Chief Engineer
    • Minnesotamodeler
Re: canard concept
« Reply #16 on: September 03, 2010, 10:20:44 PM »
Fascinating...helps explain why the CG has to be considerably ahead of the LE on a canard. 

Gives me some more ideas too...
--Ray 
Roseville MN (St. Paul suburb, Arctic Circle)
AMA902472


Advertise Here
Tags:
 


Advertise Here