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Old Oct 27, 2008, 10:00 PM
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Hilltop Fun Fly

Sunday, With 80 plus in attendance, and a near perfect weather day, the Hilltop Flyers near Loganville, Ga. had their fall fun fly. The highlight of the show was two German scale models, one a canard, which were built by the late Dan Stevens from Americus, Georgia. Dan also created the Mac Hodges B29 and the red rocket it carried. Two of Dan's sons are Hilltop members and they are proud to have their father's models. Both models were flown several times. The canard has been pictured elsewhere in this thread courtesy of Dan and others who have scratch built smaller versions. Sorry that I cannot recall the names of either model. Our club is about 10% electric and on the last raffle drawing of the day, I was lucky to win an RTF Bonny. Edit: The German canard, a Focke Wulf FW-42 is shown here on page 5 post 69. Top center picture shows Dan Stevens with transmitter with his son Mike doing a check out before flight. Charles
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Old Oct 27, 2008, 11:56 PM
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Congrats Charles!

That photo of a Blohm-Voss BV-XXX? brings back memories. I picked up one of those that was a bash job of a Sig Dazzler. Truly asymetrical, several attempts and it never did fly. I'd be very interested in not only the longitudinal CG of that model but the lateral CG as well!

Our Capital City Radio Control Club (ccrcc.org) fall fly-in was this past Saturday. Beautiful day but with about an 8-12mph crosswind. The awards presentation was delayed about 30 minutes while some fellows were looking for a downed model, the wind let up for just a bit and I flew the Georgia Goose. 10 minutes later I took the "Most Unusual/what is it/how do it fly? Award. $40 worth of raffle tickets and I managed a Hobbytown $25 gift card.

Sunday I flew the Goose a few times at the other club field; I had flown it and removed the lipo and left it on the table. Little while later I picked up a fully charged lipo and my brand new little Richmodel Quickie 380 and put them on the same table as the Goose......and the discharged battery from the last flight of the Goose.

Needless to say, the little Quickie took off in a flash, made one turn and then immediately went into LVC. I cycled the throttle and it came back for only a few seconds and then into the brush it went.
Working my way around the briars and not noticing the tallow tree that damn near killed me (HACK HACK HACK of the lungs) I found the little Quickie with a perfect canard, perfect wing and a fuselage broken in half.

You've probably guessed it....I checked the voltage on the 3s lipo and it was 10.65. I then checked the other battery on the table and it was 12.5----I picked up the WRONG battery!

Oh well!

Rube
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Old Oct 28, 2008, 10:30 PM
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Rube, I am proud that you took the most unusual prize with your Goose. Also it is good to hear that you managed cross wind flights without canard damage on landings. You had me sweating there for a while. Too bad about the Quickie. Did you get a few flights in before the crash? Look on page 70, posts 1043 and 1046 for how Lost Soul crashed his first of two Quickies. I hope you can get a replacement model and then will have spare parts. I have edited my post above with more on the German canard FW-42. Charles
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Old Oct 29, 2008, 12:46 PM
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Someones got to do the later Miles canard...................??
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Old Oct 29, 2008, 05:03 PM
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http://www.ipmsstockholm.org/magazin...o_tailless.htm

http://www.ipmsstockholm.org/magazin...o_miles_02.htm

Scroll down a little to see some lovely static display models of the Miles fleet.

I'm going to have to do some digging here, but from memory

The late Doug McHard, arguably one of England's finest aeromodellers, published a FF plan of Miles' single engined pusher canard fighter. A web search when I should have been doing something useful (making the final decal set for my 200% full scale version of Chuck Wenlock's FF rubber powered 'Sportster' from the June 08 Flying Models!) failed to unearth a source for Doug's plan, but I recall him talking about it. I googled Doug's name and got 863 hits - if you ever want to read up on a great aeromodeller, Doug was one of the finest.

Seems he built a FF model of the M35, many years ago - mid 1960s - and got it to fly. He published the plan in 'Aeromodeller' magazine, then the UK's only mag, and re-visited it some years later - and was unable to get it to fly at all, though he used his own plan and bear in mind that Doug picked his prototypes for them making unlikely FF subjects! He inevitably made all sorts of unlikely things fly far better than anyone could reasonably expect.

In the meantime, not neccesarily 'Canardly' - but this is the webside for a lot of the plans published by 'Aeromodeller' and the slightly later 'Model Aircraft'. For those who like history and/or a serious challenge, it could provide a useful source or just a slant on a different way of doing it.
http://www.xlistplans.demon.co.uk/

I suspect someone in the UK did a large RC Libellula and flew it in public, though I can't recall much beyond that I saw a photo in a paper mag a long while ago!

Another Miles M35 Libellula:
"A 9.5" span profile scale glider (or rubber-powered pusher) with a canard and swept-back main wing. Full-size plan included.
AERO MODELLER #701 Jun 1994 (v.59) pg. 26"

Was unearthed on a site called NLE Index, of which I have no idea what else it does! I was busy settling into life in another country at that time, so have no recollection of that issue, but it was late on in the life of 'Aeromodeller' as a stand-alone magazine. Anyway, I figure anyone who can contemplate a scratch design/build of a scale canard like this should have the common to start with a similar size of 'chuckie'

If there's a point to all this rambling, if you head into a model of a Miles canard (especially the jet one!), it could be a lot of fun

Regards

Dereck
(Who will now finish off that decal!)
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Old Oct 29, 2008, 05:41 PM
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Dereck

Excellent links , thank you
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Old Nov 07, 2008, 09:28 PM
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Hey I just joined today (building a new stealth plane from scratch), and I have some questions about CANARD placements...

I know for the canard to have maximum performance, they need to be some distance in front of the wings. (like this one)


I noticed a lot of modern fighter jets have canards on the fuselage beside the intake exhaust ports, rather than near the cockpit.
Could someone please tell me WHY they are placed in this location? Is there some kind of benefit having the canards further away from the main fuselage body?
EXAMPLES:




Also, I noticed some planes have canards (ones on the main fuselage body near the cockpit) either above or below the wing location. I'm assuming this is to avoid the turbulent wind from the canards flowing over the main wings during level flight and positive pitch movement ???
Anyways, I'd appreciate an explanation on this as well.
EXAMPLES:




Any answers to these questions would be greatly appreciated!
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Old Nov 07, 2008, 10:03 PM
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Re: Canard Location

It is generally bad to "mess up" the flow into the intakes. Flow off of any surface tends to be "messed up".
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Old Nov 07, 2008, 10:23 PM
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Re: martimer

Okay, so having canards (in front of the cockpit) which could affect airflow into the intakes is bad... fine.

What about those canards behind the cockpit on the top side of the fuselage compared to those beside the intakes ports?

I kinda think the ones high behind the cockpit would be better because they cause less drag on the main wings?
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Old Nov 08, 2008, 09:57 AM
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Complicated. Some of it is keeping the wake of the canard boundary layer separate from the wing. However, you also need to remember that many of the examples you brought up are supersonic fighters. A major factor there is the interactions of the shock waves coming off the canard, fuselage and wing, including during maneuvering. Subsonic aircraft like the ones we build generally don't have to worry about shock waves.
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Old Nov 08, 2008, 01:31 PM
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In some cases causing some "drag" on the main wing is a good thing because it can increase the aerodynamic efficiency of the main wing be reducing the effects of flow separation. Of course it only works at certain subsonic speeds and so is only useful for cruising/loitering. It also ends to interfere with supersonic flight.

Fascinating stuff! Personally, I think variable geometry canards are next.
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Old Nov 08, 2008, 02:25 PM
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Thanks, dredogol, for the new material. These super fast short coupled aircraft really need to be controlled from the front as I see it. It is like driving a car with front wheel steering, you put the nose exactly where you want to go. I enjoy flying my models with the positive wind penetration and ease of landing. Charles
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Old Nov 08, 2008, 04:28 PM
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Quote:
Originally Posted by martimer
In some cases causing some "drag" on the main wing is a good thing because it can increase the aerodynamic efficiency of the main wing be reducing the effects of flow separation. Of course it only works at certain subsonic speeds and so is only useful for cruising/loitering. It also ends to interfere with supersonic flight.
I presume you're referring to turbulation to prevent boundary layer separation. That really only applies to lower Reynolds numbers, such as models or on relatively slow full-scale aircraft. At higher Re's, the efficiency-improvement problem is usually more about trying to keep the flow from becoming turbulent.

There are cases of turbulation (such as vortex generators) used on higher Reynolds number applications, but there it is generally to prevent or delay stall of that portion of the flying surface. It does not generally improve efficiency (in fact it normally reduces it), but it can increase the max lift coefficient possible from the surface. It's often used as an add-on to fix handling problems, such as loss of aileron effectiveness near stall, or to increase control authority.

For example, used on the fin of a twin-engined aircraft they can allow more lift to be squeezed out of a given size fin+rudder, allowing the tail to handle more asymmetric thrust in an engine-out situation. This can fix an existing problem, or it can allow a new design to get away with a smaller vertical tail than it would need without vortex generators. However, the benefit here is not from a direct increase in fin efficiency in cruise (as before, it reduces it), but rather by allowing the fin (which in a twin is sized by an emergency situation) to be smaller. Note, vertical tails on twins are normally several times larger than what yaw stability alone would call for, just to get enough authority for the engine-out situation.

Quote:
Fascinating stuff! Personally, I think variable geometry canards are next.
A canard with a control surface on it IS a variable geometry canard. The majority of canards already out there fall into this category. A canard with variable sweep (such as on the Beech Starship) is a more radical example of variable geometry. In that case they have a wing with flaps, and need a multi-mode canard to keep the canard's lifting ability matched to that of the wing in its different modes. Beech paid a pretty high price in the form of a fairly complex and extremely flight-critical jackscrew linkage coupling the canard sweep to the wing flaps in order to pull that off. A failure of that mechanical system could immediately make the airplane incontrollable. Failure modes end up making a lot of the decisions in aircraft designs.

In all cases, for decent stall characteristics you need to make sure the canard stalls before the wing, unless you can limit the canard's capability by some other means, such as through a very "smart" fly-by-wire system. If you don't, you run the risk of a violent pitch excursion at stall. As Burt Rutan pointed out to me once, you almost never want to add more lifting ability to a canard (the typical reason for more elaborate variable geometry techniques) unless you first increase the lifting ability of the wing.

In any case, it's important to remember that it's the wing's job to support the plane, and the tail's (or canard's, in this case) job to take care of stabilizing and controlling the wing. When you start to blur those two tasks, overall aircraft efficiency generally goes down.
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Old Nov 08, 2008, 05:58 PM
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When I typed "efficiency" I was referring to overall effectiveness of the wing. My degree is aeronautical engineering but when discussing these things with non-engineers I often use terms that are not technically correct or have multiple uses to actually make things easier to understand. Most people have a clue about what efficiency means.

Sorry to ruffle feathers...
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Old Nov 08, 2008, 10:37 PM
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Okay... comparing the Canard way up front and just in front of the wings.
Correct me if my assumption is wrong:

1) Forward canards enable more pitch stability & more gentle rolling?
2) Canards just in-front of wings provide less stability and more unstable maneuverability?

If I have these correct/incorrect, please let me know.

----------------------------------------------------------------

If these assumptions are correct, then I am going to place the canards on my plane as close as possible to the wings.

However, my wing design is very similar to the YF-23 (intake port is under the diamond wing), so should I place the canards slightly ABOVE the wings to prevent the broken air entering the intake ports?
The canards will be directly on the main fuselage just behind the cockpit...


If I manage to get my sketch done, I'll be showing the front, top, and side views of the jet design.
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