I'm in the process of assembling the EAM Velocity and got around to measuring the "wing area".

It comes out close to what the manufacturer states but it also got me to thinking (that's odd)

If the canard on the Velocity "provides lift" (quote from full scale Velocity web site), shouldn't the area of the canard be figured into the "wing area", or better yet, the "lifting area"?

If so, even at 16 pounds, the model Velocity will have a "lifting area" that calculates out to a wing loading of about26 oz/sq. ft. Not bad for a plane of this type.

BTW, I will need between 2 and 3 POUNDS of lead in the nose to get it to balance, and the lead I use doesn't generate much lift (or horsepower)

Dick,
Your instincts are absolutely correct about including the canard area. In fact, since the canard must (for stability sake) be considerably higher in "loading" than the main wing, it is carrying more than its share (per sq. in) of the weight of the plane. If you figure a 30-40 percent higher wing loading on the canard, a perfectly logical assumption, then you have the canard running at upwards of 32 oz/ft, a far cry from the 26 you expected. This translates directly into minimum flight speed.
In terms of performance, the wing loading on the canard is the main issue, not the loading on the main wing.
A canard IS a kind of biplane and anybody who tells you otherwise is misinformed.
Allan

Let me make a correction on my previous post. The wing loading on the canard (after more figuring) will not go up quite as much. It still will probably be around 28.5 - rather than the 26 if figured using just the main wing.
My point is that including the canard area in the total would seem it should LOWER the wing loading but, in fact, the loading on the canard/elevator surface is HIGHER and that translates into a higher take-off and landing speed. The loading on the main wing is not the determining issue for those considerations.
Allan

The canard surface must be able to force the main wing into an angle of attack close to stall, in order to obtain minimum stall speed. To accomplish this, the canard must develop a much higher peak lift coefficient than the main wing, or the CG must be far enough aft to prevent the canard surface entering deep stall before the main wing develops close to its maximum lift. I have weighed the pros and cons of the canard versus tractor layout, and it came down to pretty much a draw. The portion of the main wing that is influenced by the downwash from the canard tail will have a lower effective angle of attack, and thus develop less lift than it would in a conventional tractor layout, and the tip portion of the main wing, which is outside of the canard tail downwash, will tend to have a higher effective angle of attack. This will tend to cause tip stall of the main wing at a lower average lift coefficient than would be the case with a tractor layout. In any case, in the full-scale world, stall/spin accidents appear to be about as common with canards as with conventional airplanes.

In most tractor layouts, the horizontal tail contributes to lift, unless the CG is at or forward of the wing aerodynamic center, although the contribution is not usually more than a few percent, due to the large downwash acting on the horizontal tail.

Pusher prop canards also suffer more from torque reaction than do tractor layouts, since they have no flow-straightening surface behind the propeller. Hovering without torque rolling would probably be impossible with an aft-mounted pusher prop.

Early aviators (with the notable exception of the Wrights) pretty much settled for the tractor layout, since it placed the center of lift well forward, permitting the engine to be at the nose, not behind the pilot, where it would present a clear hazard in a crash. I did a lot of design work on a canard pattern model, but never built it, when I reflected on what would happen in even a mild crash, when all that rearward mass forced itself up forward, tending to clobber everything in its path.

Sorry, but most conventional layouts have the horizontal tail surface providing DOWN force. This counters the wing's tendency to force the nose down. It also helps pitch stability. As airspeed decreases, the downforce of the stabilizer also decreases, and allows the nose to pitch down. This makes the aircraft increase speed. If airspeed is increased, the downforce is increased, which causes a pitch UP. This causes a reduction in airspeed. Because this is a dynamic process, a well-designed aircraft will be very tenacious in holding the trimmed airspeed, and will quickly return to it after a disturbance. Van's RV-series of homebuild aircraft are examples of aircraft that do a good job of holding their trimmed airspeed. They're very well behaved in pitch.

Using the Velocity (full scale) web site data for their airplanes, the canard area is indeed factored into the total lifting area when figuring out wing loading.

Using the wing area plus canard area versus just wing area alone to calculate "wing loading" on the model, here's the difference:

wing area alone = 1200 sq. in. At 16 pounds, wing loading is 30.72 oz/sq ft

wing area plus canard area = 1400 sq. in. At 16 pounds, wing loading is 26.33 oz/sq ft

That's a considerable difference.

And, yes, the Velocity will weigh every bit of 16 pounds, maybe more, once the necessary 2 to 3 pounds of noose weight is added.

Rotaryphile....Your comment on the rear mounted engine smashing everything in a crash on a Canard reminds me of my last crash with my Canard, shown in the Avatar at the left. I hit some nasty gusts on landing, made a poor recovery and hit the ground at about 30 degrees from vertical. The grass field was very soft. The fuselage (1" aluminum square tubing) in front of the canard wing stuck into the ground about 10 inches. The engine was still running, and about 3 feet in the air. It took two hands and some wiggling to get it out of the ground. The front gear was bent and the canard wing had sheared a 1/4 inch nylon bolt. No other damage. Flew next day. The wings are Coroplast corrugated plastic.

pettit....Hope you will post photos of the EAM Velocity. I'm not familiar with it. The 2-3 pounds of lead in the nose is terrible. My canard seems to have a wide range of safe CG.

Here's a photo. An all white airframe dosn't photograph well.

80" wingspan, 44" canard span, wood frame wing and canard with UltraCote, fiberglass fuselage

Uses an OS 1.08 with Perry pump, 14-7 pusher 3 blade prop.

Awaiting paint on fuselage (gel coat only for now)

Will be reviewed in R/C REPORT Magazine in a few months.

That's a shame about the lead.

The swept wings help the CG to be forward on a canard pusher by putting the engine closer to the neutral point. However the downside is that the propellor tips get very close to the wing trailing edge if the engine is well forward. This creates a lot of prop wash noise. I found that using an APC prop really helped with reducing this noise. (used zingers and graupners before that - both noisy when close to the wing trailing edge).

I think its poor design if you need that much lead to balance - it is possible to get this configuration right CG-wise with no lead. (I've done it).

The problem with my canard is the landing approach. I can't get the aft wing into a high drag, high alpha steady sink. I have to come in low and relatively quick. It seems hard to land the aircraft on our rough grass strip with out some longitudinal pitching on touch down which often results in the prop hitting the ground. This puts shock loads on the firewall. I guess I could move the undercarriage back and make it harder to rotate on take off.

Pettit....Thanks for the photo. I'll be looking for your article in my R/CReport.

destructiveTester....Can you post a photo and some specs on your Canard? I would like to study it. Your description of landings is very good. I have had that pitch up problem at touchdown also. My good landings are probably a little faster than conventional planes. I make around 10 landings per flight so I get lots of practice. When the winds are the worst I take up my SPAD Canard.

unfortunately i don't have any photos at present but I will post some when I get some.

specs are
5.5 lbs all up weight
inverted 40 two stroke pusher mounted as far under wing as possible
60 inch span aft wing - section NACA 2415 - 18 degrees sweep and tapered - outboard fins
about 26 inch forewing - section NACA 4415 - rectangular planform
spoilers for roll control elevator on forewing.
steerable nose wheel

Here's My Velocity in the air. Very nose heavy, but that's better than just a little tail heavy!

looks nice!

How does it fly?

Fly? I was just trying to keep it in the air!

Actually, it does fly very nicely. That canard lifting area must have helped since I overshot 3 landing approaches.

Lots of up elevator needed to get it into the air (nose heaviness) but it flew great. The OS 1.08 pulls it quite nicely. Half throttle for cruise.

I did a few rolls but no loops (probably not enough elevator left)

That's just about all this plane will do. I didn't connect the rudders but stall turns aren't in the book.

It seems to stall straight ahead, and will "porpoise" if up elevator is held.

I took out about half a pound of nose weight (I had added 2 1/2 pounds to get it to balance by the book)

The CG is now rearward about 3/4" and the manufacturer says the starting CG point is very "generous".

cool - glad you got it going!

where is the CG in relation to the aftplane leading edge at the moment?

Since the wing is swept, I don't know where I could measure it from, to give you a correct dimension.

It is 27" back from the nose. The manual says to start it 26 1/4" back and I brought it back almost an inch now.