Red Duck (Full Version)

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Remby -> Red Duck (4/11/2008 7:17:11 AM)

Getting this ready to go, RCU has no catagory to place the picture in. 1/2a can be so cool, without a ton of work.



combatpigg -> RE: Red Duck (4/11/2008 2:28:40 PM)

Looks like it should fly OK......I'm always curious about how well these fly. Good luck!



dieFluggeister -> RE: Red Duck (4/11/2008 3:35:18 PM)

I love the trim job! Very nice Remby.

Where did it balance out? I have never flown a canard so I am very interested to hear your report. I like your daring use of rudder for roll control! Hats off to you!



Remby -> RE: Red Duck (4/11/2008 5:48:53 PM)

dieFluggeister;

Thanks for the note. It looks like around 1.5" ahead of the L.E., as far as the computer is giving. This is a modified Lazy Duck, it was in the 1984 issue of Model Aviation. His was a powered glider, this should be a bit more sporty powered glider.


Combatpigg;

It ain't built for speed, that much is given, I'll post a couple of flight pictures.



build light -> RE: Red Duck (4/11/2008 10:43:48 PM)

I like it lots!
I have always been attracted to the unusual and this fits the bill nicely.

I particularly like the forward facing engine on the verticle fin. I think most Canards similar to this are pushers. Creates an eye catching difference!

Good luck on the maiden.

Robert



combatpigg -> RE: Red Duck (4/11/2008 11:26:02 PM)

How much up thrust is called out?



Remby -> RE: Red Duck (4/12/2008 4:21:17 AM)

Combatpigg;

The engine has a -2 Deg downthrust. Also, the carnad elevator is set at +3 Deg. Mind you, the plan calls for this, but this is not built to the plan @ one-to-one. The Six foot span was reduced to fit a 42" wing I had from another plane. The chord is wider. The body was reduced to keep it as close to the plan, but using the wing I already had.

This is my first carnad, it won't be my last.

build light;
Thats what I've seen as well, most are pushers. I have a few carnad plans, and this one is the only one that is like a trainer, so figured it was the one to try first.

I am sure it would take off from snow using just the body, and no gear. What other plane could do that?




OzMo -> RE: Red Duck (4/12/2008 4:26:01 AM)

way cool
can't wait for a flight report[8D]
what wing did you start with?



DeviousDave -> RE: Red Duck (4/12/2008 4:39:08 AM)

Definitely in the running for a Roy Clough Award....



Remby -> RE: Red Duck (4/12/2008 4:39:49 AM)

OzMo;

From the old Buzzard Buster I was flying three or four years ago. That plane died in a servo failure crash, but the wing survived. The pilot and windsceen are still where they were then, and he better not lean back!

In my gallery, look at the white and green one, thats the wing.



combatpigg -> RE: Red Duck (4/12/2008 4:55:14 AM)

Remby, After posting my thrust question, I got to thinking that maybe my head was screwed on 180 out. Some upthrust makes sense.
The way that I've set thrust from scratch on a plane with [in my case] a real low thrust line was to trim the elevator for neutral and hold the model at the CG kind of loosely with the engine running full blast. I had a helper work the elevator while I held the plane and felt for the changes in pressure. Anyway, in this case I needed to crank in a lot of down thrust to come up with a neutral feel while the elevator was centered. The first flight was just about perfect after doing this simple test.



Remby -> RE: Red Duck (4/13/2008 12:59:15 AM)

Combatpigg;
I pretty much understood what you were asking.

Your idea is sound for the most part. on this model, it will not work for the elevator. Only it's action through the air will give the needed airflow over the carnad, no prop-wash from the engine.

But it will work for the rudder, and will give it a test before the real test.

Thanks to youins' for the kind words on the plane, I'll let you know how it goes, and will get a flight picture or two if all goes well.



Remby -> RE: Red Duck (4/14/2008 7:35:39 PM)

"Definitely in the running for a Roy Clough Award...."

DeviousDave;
I resemble that remark!

Seriously, who is Roy?



old git -> RE: Red Duck (4/14/2008 7:46:27 PM)

Take a look at what is posted by dicknadine in the Vintage thread.

quote:

ORIGINAL: Remby

"Definitely in the running for a Roy Clough Award...."

DeviousDave;
I resemble that remark!

Seriously, who is Roy?


Dick is seemingly intent on building all of the Roy L Clough designs he can find.

They are really worth a look.



old git - - - - aka John L.



Remby -> RE: Red Duck (4/21/2008 5:44:16 AM)

Update on the Duck's flight attempt..

I balanced it at a forward point, close to the full forward position given on the computer. Started the engine, and let her go.

Once in the air, it acts like a Pelican and heads for the fish in the water. So, first flight, and we have roast duck. Damage not too bad, and this was fixed.

Next day, another go. The balance was shifted to the rear, the minimum given on the numbers. This time, the arc is larger, but still hungry for fish. The Duck bent it's beak.

Will take a bit to fix it, should still fly. Based on what is going on , it is the down thrust from the engine that is not correct.

When this was downsized,I had to push the engine higher on the rudder so the prop would clear. Thus, the engine is higher ,and causing the loop effect. I need to add more downthrust, right now it is -2 degs, and am not sure how to figure a correct thrust line. Any input from you'ins would be great, let me know what you think may help get it right.

And I can go with a 5*3 prop, and lower the mount if the downthrust deg idea flys south.



combatpigg -> RE: Red Duck (4/21/2008 6:17:56 AM)

Are you saying that the engine is pushing the plane into a dive that you can't pull out of? If so I suppose more negative is needed. Too bad you can't try the static "feel" test in front of a big moving air supply. What I don't like about designs that need gobs of vectored [wasted] thrust is that the angle needed is dependant on engine speed. I wonder if your plane is still too nose heavy for the foreplane to lift the nose? If the CG is correct, I don't see why a bunch of thrust angle is needed. The 1/2A canard I played with was a constant juggling match between CG and canard throw...finally I gave up and converted it to elevons.
Keep at it til you win!



Remby -> RE: Red Duck (4/21/2008 6:47:31 AM)

"Are you saying that the engine is pushing the plane into a dive that you can't pull out of?"

CombatPigg
Thats about it. Second try was at the minimum placement, and was launched with up elevator held in just a bit. It was better, but still took the dive.

The model that this one is based on had a six foot span, and uses the same engine. my moving it up on the rudder is my guess to the trouble. The thrust line is right over the top of the Horiz-Stab by a inch, it would be nice to know how to figure a proper thrust line. My guess is around 3.5-4 Degs negative.

Using thrust to balance a model is tricky, but not somthing the numbers can't figure out.

As long as I can figure the numbers.



combatpigg -> RE: Red Duck (4/21/2008 7:39:56 AM)

I never was able to find detailed info on setting up model canards that were in laymans terms. I think you should move the CG back until it allows you to pitch the plane up and down with it running in your hands.



Scar -> RE: Red Duck (4/21/2008 1:22:22 PM)


quote:

ORIGINAL: Remby

"Are you saying that the engine is pushing the plane into a dive that you can't pull out of?"

CombatPigg
Thats about it. Second try was at the minimum placement, and was launched with up elevator held in just a bit. It was better, but still took the dive.

The model that this one is based on had a six foot span, and uses the same engine. my moving it up on the rudder is my guess to the trouble. The thrust line is right over the top of the Horiz-Stab by a inch, it would be nice to know how to figure a proper thrust line. My guess is around 3.5-4 Degs negative.

Using thrust to balance a model is tricky, but not somthing the numbers can't figure out.

As long as I can figure the numbers.

I am having trouble following. This plane has the engine above the wing, so engine thrust applies a torque about the CG. That torque twists the plane down. Drag underneath, at the wing, thrust ahead, up on the rudder. Plane wants to dive.

Isn't the solution to tilt the engine UP? Like on a PBY? Other posts refer to negative degrees, I have always heard up thrust referred to as positive.

Or am I still confused?

Best wishes,
Dave Olson



combatpigg -> RE: Red Duck (4/21/2008 3:18:32 PM)

When trying to visualize an outcome I like to work with extremes. Picture this model with the engine pointed almost straight up....it's going to try to raise the tail and apply a downward force on the foreplane. The more aft the CG is set, the less leverage the angled thrust will have to upset the aircraft, plus the symptoms of the first crashes point to the fact that the foreplane doesn't have enough leverage or command to at least wrestle with the plane yet.
I don't care what the software says about CGs unless this program is geared to models this size.
I think the Reynolds numbers get crappy enough after you go down in size past a certain point that a successful 1/2A canards' proportions would need to be more like a tandem wing. If the foreplane is going to contribute to lift, Reynolds charts show a huge drop off for chords of less than 4 inches. This backs up the way mine flew, the small foreplane never was given enough area to contribute meaningfully to lift, all it was good for was a weird kind of pitch control/airbrake effect. When I tried to assign more lifting responsibility to the foreplane by moving the CG forward, the plane would lose pitch control and fly like the RedDuck has so far...



chevy43 -> RE: Red Duck (4/21/2008 7:23:07 PM)

I'm just going to guess widley here: First I'd try more positive incidence in the elevator. Next I'd go with more cord on the elvator.. The eleveator should have enough authority to overcome engine thrust shouldn't it!! Is the elevator a flying surface or does it have a hinged elevator on the back?

Did you do an engine off glide test?



Yuu -> RE: Red Duck (4/22/2008 2:59:50 PM)

Remby... I just went back and looked at the photo. Your forward control surface has 1/4 the area of my 049 RC canard, and 1/3 the area of my cl canard. My engines push straight from the back center of the fuse, so I have no 'moment-coupling'. Looks like the cord of the forward control surface needs to be enlarged to get the 'upward' force on the nose to keep her out of the fish. Who wants a 'fish duck' anyways.... they taste like dead fish!! Yuk!!



Remby -> RE: Red Duck (4/23/2008 7:00:41 AM)

Yuu

You just gave me a big yuc!

I wrote a long answer to many things brought forward here, and it errored just as I was posting. Gun shy, or bitter I guess, I will try again.

I will get the mdel specs posted, it may give more to work with.



Remby -> RE: Red Duck (4/23/2008 7:42:34 AM)

Red Duck:

Wingspan = 41".
Wing Cord = 6.50"
Wing Tip Cord = 6.50".
Wing Area = 266.5"Sqr In.
Wing Loading = 8.37oz with Elevator, (10.2oz without).

Elevator Span = 20.125".
Elevator Chord = 3".
Elevator Tip Cord = 3".
Distance from L.E. Wing to T.E. Elevator = 11.375".
Elevator Area = 60.375".

One Vert. Rudder
Height Rudder = 6.375".
Cord Rudder = 4.125".
Rudder Tip Cord = 4.125".
Rudder distance to Wing L.E. = 6.875".
Rudder Area = 26.29 Sq In.

Carnad C.G. 1.17" to 1.41" ahead of Wing L.E.
Engine = Cox Tee Dee .049.


Thats the basic layout, It should work if the forces can be balanced. The thrust line is going down to around -4 Degs. Chevy43 says to give a bit more up degs to the elevator, could help if the thrust deflection will not get it done.

CombatPigg has good advise, and has done this before, so keep it going. I am not very worried about the offset thrust as it is a powered glider, not a speed burner, just want it to fly. As longs it gets there, should be fun.



Remby -> RE: Red Duck (4/23/2008 7:48:04 AM)

Chevy43

I did not test glide the first trys, but am going to before the next. A good idea.

With a name of Duck, you would think it would fly, I did without thought.



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