RE: Red Duck  
View related threads: (in this forum | in all forums)

Tower Hobbies
Enter up to 4 keywords or Tower stock numbers
Logged in as Guest



Users viewing this topic: none
  Printable Version
       

All Forums >> RC Airplanes >> "1/2 A" & "1/8 A" airplanes >> RE: Red Duck
Page: <<   < prev  1 2 [3]

Login
Message << Older Topic   Newer Topic >>
RE: Red Duck - 6/15/2008 4:38:55 PM   
Yuu


 

Posts: 329
Joined: 9/4/2006
From: Shawano, WI, USA
Status: online
This 'Red Duck' has been "stewing" long enough for the meat to fall off the bones !! Did she get thrown into the burning barrel?

(in reply to Yuu)
       Post #: 51

RE: Red Duck - 6/17/2008 9:38:21 PM   
Remby


 

Posts: 621
Joined: 11/2/2002
From: Russell, PA, USA
Status: offline
Yuu;
Yes, it was well done a while back, meaning it is ready to get finished. The other Carnad was tried, a pusher. It did fly, but controls were a bit off. Have you ever hand launched a pusher? I thought it would work, and was happy to see it can be done. The ducks wing is now on another rebuilt plane, and flys well.

The duck is fit to the EZ bee wing, and a recalc of the data will be worked out, the data Yuu (you) gave mirrored what the program gave.

A picture of the other Carnad. Will keep it all up to date very soon.

Attachments
Click to see fullsize image.
Click for fullsize


_____________________________

1/2a flyer !

(in reply to Yuu)
       Post #: 52

RE: Red Duck - 6/19/2008 1:01:33 AM   
Yuu


 

Posts: 329
Joined: 9/4/2006
From: Shawano, WI, USA
Status: online
Hmmmm.. a black and white 'duck'... on the East coast I think they call that a "Brant". The twin tails on the 'Brant' look sharp!

(in reply to Remby)
       Post #: 53

RE: Red Duck - 6/22/2008 7:16:01 AM   
Remby


 

Posts: 621
Joined: 11/2/2002
From: Russell, PA, USA
Status: offline
Yuu;
I have found out quite a bit from these two attempts at Carnads. The "flights", along with info and suggestions from the interested 1/2a'ers like Yuu are helping get these back into the air. The elevators need more positive angle to keep the nose up, and the engine offset is also very much a "must have correct" for the thing to fly.

Data to build Carnads, more so in this class of build size, requires some changes to a larger plane's plan. Trouble is it is trial and error, and that adds another strange attractor.

C.G. programs work, but do not supply everything one needs to know to make it work properly. the "feel" of these are not like a "normal" plane, some of the just do this or that things must be set aside with the elevator up front. It can be learned, but new ideas must be soaked in to be used.

These "Ducks" were both scaled down from larger planes, the angle changes are required as Combatpigg was talking about. And the angle of attack of the wing, elevator, and the engine power offset, these require more balance interaction between them so the whole thing will sail long proper.

There are Carnads that were already flown as 1/2a, but not very many. The Lazy Duck was a 6' span as the plan shows it. The Trident was a true 1/2a Carnad pusher.

This rant is just about brain overload, a purge of thought.

I guess it should be said, I never want to eat Duck again.

_____________________________

1/2a flyer !

(in reply to Yuu)
       Post #: 54

RE: Red Duck - 6/22/2008 6:15:41 PM   
BMatthews



Posts: 8951
Joined: 10/4/2002
From: Burnaby, BC, CANADA
Status: offline
All in all a wonderful modelling journey.

I have to admit that I just more or less scanned quickly through the posts but I'd like to stress a couple of things for the Duck. First is that it is large enough and light enough to test glide into the proverbial tall grass. Preferably on a day with a bit of steady headwind. Look for signs that it wants to lawn dart, stall or seems stable and wants to settle in with no bad habits. If the wind is strong enough you can also run with the model held overhead and lightly gripped between two fingers at the CG location and feel for the model wanting to pitch up or down. What you want to feel is a light sort of bouancy without a strong tendency to try pitching or lifting and dragging back. When you can feel that sort of behaviour you can push it ahead into the wind and it'll almost certainly be ver close to glide trim.

On oddball thrust line models the aim is to try to direct the thrust line so that it goes through the CG. So a forward wing mounted pylon would want to see upthrust. On glider pylons it's not uncommon to see 6 or 7 degrees of upthrust. More offset is requred the closer to the CG the engine is located. On your Duck with the engine's prop located so close to the CG location I suspect that 4 degrees of downthrust is not unreasonable at all and you may well end up with 8 to 10 before it settle down and flies right.


_____________________________

Bruce-
Proudly wasting balsa since 1965.

Free Flighters go that extra mile........

(in reply to Remby)
       Post #: 55

RE: Red Duck - 6/23/2008 4:17:13 AM   
Remby


 

Posts: 621
Joined: 11/2/2002
From: Russell, PA, USA
Status: offline
BMatthews;

Thanks for the input and thoughts. It will get a test as you described, I like the way you placed that picture in my head, it makes getting it ready a set goal to work for.

The offset description also fits with what I have seen from the tests. Pushing it through the C.G. will be quite a bit downthrust.

The radio was removed from the Duck after its last dive, the switch was destroyed, and the radio needed to be checked out from this damage. I can install the radio after the body is repaired and given a slight upgrade for nose strength. The final layout will need a recalc of the C.G. It won't look like it did, but I really would like to see it fly, thats the goal.

_____________________________

1/2a flyer !

(in reply to BMatthews)
       Post #: 56

RE: Red Duck - 6/23/2008 7:55:24 AM   
Thomas B


 

Posts: 456
Joined: 7/14/2002
From: Fort Worth, TX, USA
Status: offline
I want to log in as being opposed to the down thrust idea...

Take a look at the pic of the Lake Renegade aircraft I have attached. Note the large degree of up thrust in the thrust line.
Note that the prop arc is in a pretty similar location to the Red Duck...above the trailing edge area of the wing.

Yes, the Red Duck has a CG a little bit further in front on the wing leading edge than the Lake Renegade. I still think the upthrust will help. you may need 5-6 or even ore degrees.

I found that some upthrust on my Electrifly EP Seawind (motor on extension in front of fin, prop arc above rear of wing near trailing edge) notable reduced the nose down tendancy under power, at low airspeed (no problems either way at higher airspeeds)

Airspeed will help as well...once the Red Duck is moving well, the aerodynamic effects will start to outweight the thrust line effects

Attachments
Click to see fullsize image.
Click for fullsize


_____________________________

Electric Coolhunter

(in reply to Remby)
       Post #: 57

RE: Red Duck - 6/23/2008 5:50:09 PM   
Demon-Leather


 

Posts: 120
Joined: 12/11/2001
From: Rex, NC, USA
Status: offline
I love Canards (I love anything different ) I haven't got the intestinal fortitude to try one yet.. but, I'm well armed with lots of plans when I do! I'm hesitant mostly due to my flying skills with conventional planes. One of the plans I wanted to attempt was the Piper PAT-1 (Piper Advanced Technology) which was going to be the first all composite canard commercially produced. Unfortunately, the main push behind it, Howard Piper, died just before the maiden flight in June 1981. Then the only prototype crashed in a demonstration flight killing it's designer George Meade & 2 NASA employees in Nov 1981...So you can see you are not the only one having trouble with canards.
The other, is the plans for the Varieze. Both are free flight rubber designs...the PAT-1 is a peanut, and the Varieze is a 25" span. I'm considering enlarging them for powered flight, and even making them from fan fold insulation board (that way, they "bounce" when they crash) I have the Variviggen, a very interesting 30's French design,.. and a few others but can't find them at the moment in my mess Bob


Attachments
Click to see fullsize image.
Click for fullsize
Click to see fullsize image.
Click for fullsize
Click to see fullsize image.
Click for fullsize



_____________________________

Demon-Leather
Experienced crasher

(in reply to Thomas B)
       Post #: 58

RE: Red Duck - 6/24/2008 5:14:58 AM   
BMatthews



Posts: 8951
Joined: 10/4/2002
From: Burnaby, BC, CANADA
Status: offline
The thrust doesn't need to be all the way directly through the CG. But it should point fairly well towards it.

I have to admit that the Lake picture runs afoul of what I'm suggesting. However without seeing the sometimes odd wing incidence arrangement that some full sized aircraft use and that the Lake may well use as well it's hard to say just where that thrust line is located although it sure does seem like it's the "wrong" way by my theory. One thought is that it's angled the way it is so it pushes down onto the stabilizer. If the stabilizer wasn't up on the fin like it is perhaps they would have chosen a different thrust line angle.

In any event downthrust on the Duck will produce some nose up torque which from the accounts is what it needs. But I have to admit that it may also be from the wing setup as well as a not hard enough throw. Hence the suggestion to do the running two finger pitch test and move from there onto actual test glides over the proverbial tall grass and only then fire up the engine again.


_____________________________

Bruce-
Proudly wasting balsa since 1965.

Free Flighters go that extra mile........

(in reply to Demon-Leather)
       Post #: 59

RE: Red Duck - 6/24/2008 8:23:54 AM   
Remby


 

Posts: 621
Joined: 11/2/2002
From: Russell, PA, USA
Status: offline
Agreed, the test glides come first, and it will need more down thrust. It is hard to get a feel for the negative thrust line, but it becomes clear very fast when it leaves your hand, it is needed.

_____________________________

1/2a flyer !

(in reply to BMatthews)
       Post #: 60

RE: Red Duck - 6/24/2008 8:41:02 AM   
Remby


 

Posts: 621
Joined: 11/2/2002
From: Russell, PA, USA
Status: offline
Thomas B;
The Duck has to have up-thrust. Your picture of a seaplane is not quite the same as the carnads I've been testing the waters with. If you had seen the test flight, you would agree after the laughing died down.

Carnads are cool, even sitting on the grass.

_____________________________

1/2a flyer !

(in reply to Remby)
       Post #: 61

RE: Red Duck - 6/24/2008 2:41:10 PM   
combatpigg



Posts: 9830
Joined: 11/22/2003
From: arlington, WA, USA
Status: offline
You could take the running pinch test a step further and set up shop in the back of a pick up truck, complete with tools and materials to modify the thing until it yields smooth and stable pitch control. I would run a rod through the plane at the calculated CG.....[actually having a series of holes pre drilled would be better] and also have a means to add or subtract areas, change angles, etc.
The other thing to do if all else fails is to call Barnaby Waifan for a lecture.

_____________________________

Led Zeppelin is NOT "old fogie" music.

(in reply to Remby)
       Post #: 62

RE: Red Duck - 6/25/2008 1:39:15 AM   
BMatthews



Posts: 8951
Joined: 10/4/2002
From: Burnaby, BC, CANADA
Status: offline
My only issue with doing it standing in the back of a pickup is that the air arcs up and over the cab so you're not getting direct flow. To achieve that sort of flow you'd need to mount the model well above the bed or well out in front of the front grill by about 10 or so feet.

Other than with gliders and old timers the models tested using the running pinch test won't fly from your hand unless you're running into a rather stiff breeze. However it will show a tendency to pitch up or down strongly enough to produce the sort of results the Duck seems to have had up to now.


_____________________________

Bruce-
Proudly wasting balsa since 1965.

Free Flighters go that extra mile........

(in reply to combatpigg)
       Post #: 63

RE: Red Duck - 6/25/2008 5:01:35 AM   
combatpigg



Posts: 9830
Joined: 11/22/2003
From: arlington, WA, USA
Status: offline
If you can gain access to any large airhandler equipment [if you work in a skyscraper, hospital, school, etc.] or where there is any other kind of big air mover...that is where to set up shop then. Some equipment rental shops have huge portable fans also. When I was goofing around with a scratch built canard and getting nowhere, I should have gone this route instead of crash, repair, modify, crash, repair, modify.

_____________________________

Led Zeppelin is NOT "old fogie" music.

(in reply to BMatthews)
       Post #: 64

RE: Red Duck - 6/25/2008 6:28:28 AM   
Remby


 

Posts: 621
Joined: 11/2/2002
From: Russell, PA, USA
Status: offline
Combatpigg;
Its up to date to say its been.. Crash(duck roast),repair, modified, crash, repairs underway..

And thats the way it is.

_____________________________

1/2a flyer !

(in reply to combatpigg)
       Post #: 65

RE: Red Duck - 7/19/2008 3:56:36 PM   
Yuu


 

Posts: 329
Joined: 9/4/2006
From: Shawano, WI, USA
Status: online
Remby, don't get discouraged. The "Red Duck" has become a challenge, evev though the radio needs to be fixed, and the previous flight brought lots of laughter from the 'peanut gallery'. You don't see any of THEM trying, do you? Bah!! Sissies. In the thread "Little Seaplane 'Aqua Star'" there are comments on engine thrust. Post 15 says 'three degrees upthrust to pull the plane from the water' . Post 17 says there is an 'error addendum' in the box saying to change the 3* downthrust [shown on the plan] to 3* upthrust.... Post 18 shows the location of the prop over the NOSE ....And post 17 says "3* upthrust puts the prop blast over the elevator". Well, AIN'T got NOTHIN' to do with the engine located on the back end as yours is for the canard!!

Your post above states the elevator needs more 'up'... well, the entire foreplane of my canard is tilted 3* up in Front, and elevator neutral is level with the foreplane. [3* up also] I would set the engine thrust level with the top of the fuse.

Post 54 says you n