There is a great article on this Anti Yaw Device
in the October issue of MA.

Can't wait to try it.


Bob

It's an interesting name for a weight in one wingtip.

The "device" is a wingtip weight.

Anyone care to work up the comparison between a side mounted motor versus an ounce or so of wingtip weight? Just wondering, as we already have an existing set of test subjects to consider. There would be a fair number of models that already have those "devices" or at least a virtual equivalent. They should have been testing the effectiveness of the concept for quite awhile now.

I know it's just wing tip weight.

All of my engines are mounted upright,
and my Astro Hog does yaw hard left
after take off.

Bob

So your Hog will provide a really good test vehicle.

BTW, they all turn left on takeoff if you push the throttle too fast.

It's because the prop is working great but everything else isn't yet or just barely getting started. The fin/rudder have barely got their usual power. It comes with airspeed and there isn't much, and what airspeed they're seeing is coming from the propblast on one side.

But the weight is an idea that's not universally preached. It will be interesting to hear other's observations of it. And of course, everyone with a sidemounted engine will have seen something of the effect.

I agree,


Waiting for our field to dry up after all
the rain 10 + inches.


Bob

i have the modern airplane news
where is the articale? which page?


is this refering to multi engine yaw effect?

how about to mix the rudder to the TH to compensate the yaw of the engines or to add a gyro on the rudd?

I already had an anti-yaw device. I call it a rudder.

Me too. Works very good IMHO. I also have just a tick of right thrust to help offset the tendency to yaw left from P-Factor.

I have a side mounted engine in my Tsunami..... but I put weight in the opposite wingtip to balance it. Isn't lateral balance supposed to be a good thing if you want an aerobatic airplane that tracks well?

ChiefK

Wingtip weight should be determined by how it flys, both inside and outside loops. However the article kind of mentions that the asymetrical tip weight is more for airplanes that avoid actual acrobatics.

The effects of the weight of a horizonally mounted engine is very small (yes, lots of weight, but a very small moment (distance from center line)). On pylon racing models, weight usually ends up on the right tip even with the engine side mounted with the cylinder on the right side as well. The reason is that in the turn, which is just half of a horizontal loop, the increase in the angle of attack makes the prop blade on the right side of the airplane do all the thrust, while the other side is doing very little if any.

I always added tip weight to the left wing on my racer to keep that wing down in the turn. I think right thrust and piloting skills are all that is needed here. Hi thrust, hi angles of attack, left yaw. That is the rule.

I certainly agree that final trim (including balance) is based on actual flying characteristics, but "balance" at the recommended CG as well as laterally is probably an appropriate starting point. I also agree that the side mounted engine requires very little weight in the opposite wing. The idea of deliberately "unbalancing" the airplane laterally seems strange to me. I guess I overlooked the caveat about aerobatic airplanes when I read the article.

Thanks for the pylon racer perspective. I did not know that they did that.

ChiefK

Magazine is Model Aviation.

The article focuses on the left turn most planes exhibit on takeoff. That's more often a result of too much throttle too soon. His theory is that a mass far out in the right wing will cause it right yaw.

Pattern planes very often are balanced laterally by flight test result. That is certainly a very sensible way to arrive at any lateral ballasting a flyer would wish for. It seems humorous that anyone would feel that poor takeoff technique would be worth laterally imbalancing the airplane and probably influencing flight characteristics negatively.

If'n the model balances out in a static test (and most will not) then the last thing I do is add any unbalance setup such as tip weight
One thing lot of aerobatic guys do NOT do , is to balance the airframe about the prop axis
For those who wonder if this really counts - try some good ol flat foamies with the battery mounted high -above the wing and low below the wing
Now do your full routine of rolls snaps etc..
It can and does make a difference on hard core aerobatic models.

Right, and tuning aerodynamically isn't anything like sticking nails into wingtips based on how the sucker tips when you grab it by the nose.

I actually know a couple of aerobatic guys who in fact did balance with weight, but others would not wish for lateral balancing by the addition of mass. "would wish for"..... Don't know any who ever did wish for or add weight. Always adjusted stuff, like adding differential.

easy now,

I was just think about this Topic for my A. Hog.

I am bye far a Great Pilot, but know when
something is causing my curiousity to learn.

Bob


Keep The Faith .

I haven't read the article, but it sounds like the guy is trying to think outside the box a little bit. I can see how if weight is added to the right side, that side of the plane will accelerate more slowly, causing a right yaw in order to cancel the left yaw caused by the propeller. The uneven wing loading will of course affect stall characteristics with the engine off. Hmm....what if the wing area was also increased on that side? The added weight and drag from that could allow for some of the other wingtip weight to be removed and the idea would be to keep an even wing loading. I think the Macchi 200/202/205 series fighters from WW2 did something like that, with one wing longer than the other one.

Yes, Dick has an excellent point here. That so called "CG" point on the plans is not an indication of where the CG should be. More likely just placed on the plans because no structure was drawn there. All it shows is the balance point with the model level.

A few years ago I asked a famous TOC pilot about balance in the vertical plane. His blank look and rambling answer told me that he had never thought about it.

So, does say a 27 ounce mass with a CG say 2-3 inches from the pivot point produce more torque than say 1.5 ounces placed 30 inches from the same point?

Or should we ignore the 27 ounces for some reason.

were you looking fora dynamic response concerning a rather static problem?

Dick's having fun with you.

Static balance, a 22.5 oz weight at 2 in is the same as 1.5 oz at 30. OK if you never fly it.

But the dynamic balance would be way off (weigh off??), since the moment of inertia is proportional to the distance squared. The moment of inertia (the total summed up) defines at what point of the roll axis the model will roll about when a force is applied. Further more, you could not just move weight up or down the design at one point and fix the problem. Think about spin balancers for tires. Weights go on both the inside and outside rim for best dynamic balance. So if servos are also mounted in the tail, their vertical position could be just as important as moving the battery up or down. Or the weight of the tires.

I would suggest that the difference between a good flying airplane and a great one is where the components are mounted. Fortunately most of us are not good enough pilots for it to matter, and no amount of transmitter mixing will fix these problems.

Now we're talkin'

So could someone suggest that the simple solution is jest a bit too simple? That aerodynamic problems usually don't have one liner solutions?

This reminds me of the reasoning for why some guys automatically crank in some right thrust...because just a tiny amount of left thrust [accidentally] is so detrimental. I guess if you could pick a side to be off lateral balance wise, the starboard side is much better than port.

Control line flyers have known about and exercised good lateral CG hygene for decades.

After reading the article word for word for about the first paragraph, they began to lose my attention once I got the feeling that they were reporting about some kind of panacea or magic elixir. I'm kind of surprised that MA ran the article in that light, like they had just invented a glowplug that never burns out.

When is a hinging not on a hinge line?
PS -I started "flying " with a Veco Brave and an O&R 23 backport.
Also, went thru a StuntWagon /Barnstormer/Nobler/myown sstunt ideas before I picked up a Transmitter
Even built a biggie in the eighth grade powered by a Bluestreak 65- -all I could do to stay on my feet.

I thought these were called "rudders"...