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Old Nov 17, 2008, 04:03 PM
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Joined Oct 2006
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Hello:
It my first message in this topic, first of all congratulations for your evolution in the canard world. Now, Im desingning a canard model, for a 50cc. But I want to select the best airfoil configuration, which airfoil do you recomend me for the canard and the wing? I attach an excel program that help you to calculate the basic dimensions (the zip archive).
Thanks for all. Yours faithfully
Jess
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Old Nov 18, 2008, 10:31 PM
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South - Africa
Joined Nov 2007
232 Posts
This is my first post to this forum. I love deltas and so like the idee of the double delta canard and would like to build one. I could'nt find plans for one. I know that there are lots off info scattered on this site and that all off my wuestions has probably already been answered, but could you help me with some of the design criteria for a double delta?

How important are -
- profile - I've got a symmetrical I like to use on my deltas
- canard location - higher or lower than the main wing
- pusher or tractor - much easier to get tractor props here than pushers
- incidense - relative to thrust line and to one another

Canard size?
controll surface size?

and the most importand is the correct way to calculate c of g?
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Old Nov 19, 2008, 02:20 AM
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G_eronimo's Avatar
Near Koblenz
Joined Oct 2006
284 Posts
Quote:
Originally Posted by EINA
This is my first post to this forum. I love deltas and so like the idee of the double delta canard and would like to build one. I could'nt find plans for one. I know that there are lots off info scattered on this site and that all off my wuestions has probably already been answered, but could you help me with some of the design criteria for a double delta?

How important are -
- profile - I've got a symmetrical I like to use on my deltas
- canard location - higher or lower than the main wing
- pusher or tractor - much easier to get tractor props here than pushers
- incidense - relative to thrust line and to one another

Canard size?
controll surface size?

and the most importand is the correct way to calculate c of g?
Everything is important.
So, no easy answer to your questions possible.

I don't see, why a symmetrical airfoil should not be possible for the main wing.

The location (and size) of the canard depends on your preferences. Every position has its pros and cons.

With a brushless motor it doesn't matter, if there are pusher props available. Just use the tractor props for pushers and let the motor run in the other direction. (You did not mention, what type of motor you would like to use)

There must be plans somewhere from these planes for example:
http://www.rcuniverse.com/forum/m_8056765/tm.htm
That would be a good starting point for your own design.
You don't need EDFs for them as you could easily use a pusher motor.

There was software mentioned earlier in this thread for the calculation of CoG (I don't know where, as I did not use it up to now).

Uli
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Old Nov 19, 2008, 03:21 AM
What could possibly go wrong?
nickchud's Avatar
Market Harborough
Joined Apr 2006
3,696 Posts
CoG Calculator

Here it is

Worked a treat for me, as a canard beginner.

cheers

Nick
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Old Nov 19, 2008, 12:42 PM
INDORUS EXPARAMINTO
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Springfield, Missouri, United States
Joined Jul 2002
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Link to the Telos
http://www.rcgroups.com/forums/showt...9#post10971962

Larry
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Old Nov 19, 2008, 02:31 PM
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South - Africa
Joined Nov 2007
232 Posts
Thanx for the replies. The models in the links are a bid above my building skills ( and patiance) at this moment. I think I will just build 2 delta's ( the same exept the size ) join them with a fuz, do the cg and see what happens. I've got a OS 61 that needs a plane.
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Old Nov 19, 2008, 02:53 PM
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Don Stackhouse's Avatar
United States, OH, Bradford
Joined Jun 2005
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Quote:
Originally Posted by EINA
Thanx for the replies. The models in the links are a bid above my building skills ( and patiance) at this moment. I think I will just build 2 delta's ( the same exept the size ) join them with a fuz, do the cg and see what happens. I've got a OS 61 that needs a plane.
Before investing in one big enough for the OS 61, try making a scaled-down balsa free-flight glider, maybe about 6" to 10" span. Fly it in your living room or garage, experiment with C/G and incidence, get all of those in the ballpark using something cheap and simple before making something big and expensive.
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Old Nov 19, 2008, 03:13 PM
Sink stinks
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United States, GA, Atlanta
Joined Apr 2005
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Quote:
Originally Posted by SPEED-E-FLYER
Looks cool. I wish I had a mountain around here so I could try that.
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Old Nov 19, 2008, 07:28 PM
Jets are for kids-of all ages
Florida, USA
Joined Jun 2008
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This is my first time on this forum, but after finding it thought it would be helpful. I love canard aircraft, (velocity, cozy, long-ez) etc. I have built one velocity out of foam board to test the concept. Even though it was under powered, with a Park 450, it flew beautifully. It was very stable, and smooth. First flight I tried a stall to get a feel for it. It went into a deep stall, and even full power, full down pitch, would not recover it, so I let it fall like a leaf. Just broke the main gear, had it flying again that afternoon. After moving the cg forward it flew and stalled like it was supposed to. Then I got used to the landing speed, it made great touch and goes. Now I have built a bigger version, more power, haven't tried it yet. Maybe this weekend. Anyone know of any plans for a Long-ez balsa and ply (electric) version?

Check my blog for more photos and a video of it flying.
Roger
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Old Nov 19, 2008, 08:05 PM
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Sydney, Australia
Joined Mar 2006
1,315 Posts
Quote:
Originally Posted by EINA
This is my first post to this forum. I love deltas and so like the idee of the double delta canard and would like to build one. I could'nt find plans for one. I know that there are lots off info scattered on this site and that all off my wuestions has probably already been answered, but could you help me with some of the design criteria for a double delta?
Hi EINA,
Nick has already given you the right answer regarding the CoG calculation. I'd just like to add that a static margin of 10% works well for the models I have built. I have never built a delta canard model myself but for what its worth, I will give you my thoughts anyway.

Symmetrical airfoil should be workable for a canard delta. If it was my design, I would rather use a low camber semi-symmetrical airfoil and use elevons on the main wing to assist with pitch control. For a conventional delta model, a symmetrical airfoil is often recommended to get the necessary pitch stability. On a canard model the forward wing incidence should be set as required for pitch stability. I think this alllows a bit more lattitude in airfoil choice for the main wing than on pure delta model.

Regarding location of the canard wing - I think there exists an optimum location for maximising efficiency and minimising drag. The efficiency aspect would be important for a sailplane, but for a power model I wouldn't worry about it too much. The theory I read about for full size jet aircraft is that a canard aircraft can achieve the highest max CL by placing the canard wing higher than the main wing. Apparently it has something to do with the canard tip vortex reducing the pressure above the main wing.

Tractor vs Pusher - For canard models I think that pusher is better because it won't directly affect the airflow over the forward wing. If you use a tractor, there is an increased risk that the main wing can be stalled before the canard, which will lead to a complete loss of control or flat spin, etc. No matter whether pusher or tractor is used, I think that all IC powered canard models need a good chunk of ballast to get the CG correct. My suggestion would be to keep the OS61 for another project and build an electric powered canard model. Please feel free to disagree if you prefer IC power!

regards,
John.
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Old Nov 19, 2008, 10:04 PM
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South - Africa
Joined Nov 2007
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John 235

Thank you for your input. I've always received good advise on this forums - even helped me to get my f117 stealth flying against all odds at my local club.

I've only recently started with electrics so I don't have alot spares around, if I go IC it wouldn't be because I disagree it would be because its what I have.

I think that using a pusher would be better for getting the cg more constand between full and empty tank. The distance between the cg and the tank would be long and that will have a uge impact when it gets empty.
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Old Nov 21, 2008, 06:43 AM
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Sydney, Australia
Joined Mar 2006
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EINA, Do you have some idea about the delta angle you would like to use on your canard?

I am thinking of a new canard model using a main wing with a leading edge sweepback of around 30 degrees. I don't think it can really be classified as a true delta. For airfoils I would probably use a NACA1408 (8% thick) at the root and NACA1410 (10% thick) at the tips. Mine would be smaller than 60 size at around 43" span and 3lb.

Please keep us updated with your progress.
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Old Nov 21, 2008, 09:12 AM
Jets are for kids-of all ages
Florida, USA
Joined Jun 2008
2,892 Posts
Does anyone know of any plans for a built up Long-ez or Cozy of Velocity? I would like to build one, just trying to save some time and effort, from having to draw my own plans.

Roger
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Old Nov 21, 2008, 01:40 PM
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South - Africa
Joined Nov 2007
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john235. On my deltas I use the SD8020, its fully symmetrical and not to thick. As I am no expert I hear a lot of theoretical arguments about waht is delta and what not, about profiles, le or te sweep exc, exc..... My believe is that if you have a delta of 45 deg and you change it to - 45 deg you've had a delta then a wing then something I haven't seen before, but if there's a wing, engine and the cg is right it must fly.

It looks like the NACA1408 has a little downward lip at te, it would give like an under camber where they usually recommend a reflex for wins and deltas.

This forum is not about deltas and I think that alot of the "delta" rules would change a bit. My experiance also are that you need more power for a certain wingspan on delta shape then for a normal wing.
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Old Nov 21, 2008, 05:10 PM
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Sydney, Australia
Joined Mar 2006
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Roger, Just in case you didn't already know about the 40 size IC powered Long-EZ from Nitroplanes.com, here is the link. http://www.nitroplanes.com/arfloez46von.html

They used to do a smaller electric version, but the the information seems to have been removed from the site now. That version features in a couple of places in this thread.

There is some information about conversions to electric for the 40 size version here:
http://www.rcuniverse.com/forum/m_48...oplanes/tm.htm
http://www.rcgroups.com/forums/showthread.php?t=433051
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