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  #1  
Old 02-27-2005, 06:29 PM
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Quote:
Originally Posted by Dust
adouglas, build a cozy and stay away from ice and thunderstorms, stay safe and always be petrified of ice, please.
Perhaps you misunderstood me.

I neither said nor implied that I would ever knowingly fly into icing conditions.

That would be stupid (or, as I like to say, "thtoopid"). And despite what my wife might say, I am not stupid.

But Ma Nature has a habit of whacking you up side the head sometimes whether you like it or not and if you have an instrument ticket, sooner or later you will encounter those conditions even if you try like hell to avoid them. Fellow instrument pilots, please chime in. Am I right? Have ANY of you managed to completely avoid ice or other conditions that you did not want to fly into?

That's why I brought it up in the first place. The lore as I understand it about canards having real problems with surface contamination is that if you pick up even light rime icing (at a level which is not a problem in a conventional airplane) you're descending whether you want to or not. And given the more highly loaded nature of the canard vs. the wing, wouldn't equal contamination on both airfoils automatically cause a pitch down? Roncz or not, this follows from a sheer logic standpoint.

Having encountered light rime icing on a few occasions (not intentionally) I know firsthand that it does not cause a conventional airplane to do things that you don't want it to do when you're at cruise speed. I've never gotten beyond that level of airfoil contamination or had ice on the wings when low/slow, so I cannot speak about moderate or severe icing or the effect of any ice at all during takeoff or landing.

The concern I expressed was about the different responses of the two types of aircraft to adverse conditions that are commonly encountered in IMC. If I understand all of this correctly, the flight characteristics of a conventional tractor design in this particular scenario are better than those of a canard.

I may be wrong about the canard's flight characteristics. Once again, I have no direct experience and invite comment from those who do. Those who do not, please state your views as the opinions they are.
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  #2  
Old 02-27-2005, 07:07 PM
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From the various descriptions i have had on icing on a canard and icing on a regular plane, the only item that seems to stick out is that on a canard configuration, with the canard in your view, you notice the icing quite a bit sooner than in a regular plane.

My plane buddy, nick the greek, was flying last week and noticed that his airspeed had dropped by 15 knots, wondered why. Found he had ice and had accumulated quite a bit of it.

The reason that we have the option of the ice shield on the canard, I believe it is for the counterweight, is that it was found that ice can jam the controls without it.

I looked for the description of the one that had it and cannot find it. I didn't move this post to keep the other thread about me, i moved it because Ice is always a good subject to talk about.

I know that i will occasionally run into ice in Michigan in winter. From the descriptions i have read of it, it is quite simple - the same as i have read of other planes - stay aware and get out of it.

With my projected high flight plan, the amount of time i will be subject to conditions that can have icing is during ascent and decent, which is part of the plan.

Now, would i install a weeping system on the leading edges and the answer is ????? - seems to be the more who have it the more who use it and the more that don't make it through it.
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  #3  
Old 02-27-2005, 08:45 PM
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just went to the ntsb site and searched experimentals and icing - well, of course icing is mixed with carb icing, i think it was 13 fatalities in the last 3 years, have to say it - 2 or 3 rv's, no canards, a seawind and others - descriptions are long and sad. the ones i read a few pages of were done by ATP's

The problems seemed to go on for a while, in other words, they didn't leave the icing conditions quickly and paid for it.

Altho icing is a serious problem, it does not appear to kill many fliers, now carb icing - has allot of bad results - but mostly in the non fatal, ruin the day and the airplane variety, I'll stick with fuel injection
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  #4  
Old 02-27-2005, 09:24 PM
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Quote:
Originally Posted by Dust
just went to the ntsb site and searched experimentals and icing
Don't limit your search to experimentals. I'm talking about aircraft configurations, not whether it was built in a factory or in a garage.

Even if you did limit it to experimentals, raw numbers are misleading. There are over 4,000 RVs flying. Nowhere near that many canards. So if you look at it on an hours flown or population basis, you'd expect different results.

Besides that, you have to take into account the missions...I seriously doubt there are any IFR VariEzes...or any IFR RV3s. People are certainly flying IFR in RV6s and RV7s, and in Cozys (I think).

Then there's pilot qualifications/experience...Cessna 152s have a higher accident rate than 182s not because they're more dangerous airplanes, but because they're flown more often by student pilots.

FWIW, when I was working for Aviation Safety magazine and did these calculations, I used accidents per 100,000 hours flown when comparing different aircraft types. Even that is extremely misleading if you have a very small sample size.

Bottom line is that it's very difficult to draw meaningful conclusions from accident data unless you have a LOT of accidents with a LOT of common factors, which implies a LOT of aircraft to begin with, with a very consistent usage pattern and pilot profile. There simply aren't enough canards out there to meet that standard, so we have to rely on anecdotal reports.
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  #5  
Old 02-27-2005, 09:39 PM
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Statistics RULE my life

You seem to think that there are very few canards flying, i think there are many. If you look at the vari,long,cozy3,cozy4 direct lineage and compare that to the RV numbers you might be surprised. I don't include velo,sq,berk,eracer as they were not burt design or approved design and it would not be a true accumulation of one designers planes, as the RV SERIES is.

no matter how you slice 13 fatalities in 3 years you will not get any real info, especially when some of them were carb icing. Also, as there would probably not be any canards in the certificated world, adding that info in would skew the results in the wrong direction.

The point is, many of all configurations and planes inadvertently fly into icing conditions, see the error in their ways and leave it, shaken, but unharmed.

Very few fatalities result. we lose in all of GA about 135 per year, total. for experimantals in 3 years about 6(some of the 13 were carb icing).
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  #6  
Old 02-28-2005, 01:36 AM
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Default weeping?

Pardon me Dust, what's a weeping system? I've heard of leading edge heaters and leading edge boots.
  #7  
Old 02-28-2005, 05:10 AM
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Quote:
what's a weeping system?
Ah. That would be the kind that doesn't work when you need it.

Sorry. Working late. What can I say.
I think it the "weeping" type dribbles deicer out through little holes or something.
  #8  
Old 02-28-2005, 09:06 AM
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Default Whaaa...whaaa.....

Yes.

http://www.weepingwings.com/

It pumps ethylene glycol (deice fluid) through teeny-weeny laser-drilled holes (a bit larger than a human hair) in the leading edge.

On the TKS systems that you buy for spam cans, they install porous titanium panels on the leading edge of the wings, a slinger ring on the prop and a spray bar on the windshield.

The TKS system without fluid weighs 40 lbs.

They claim it has both an anti-ice mode and a deice mode, which I believe differ only in the volume of fluid being pumped. My impression from years ago when it first came out was that it was not as effective at deicing (actually removing ice that has formed, as opposed to preventing ice from forming in the first place) as other systems such as boots, but that may not be correct (or they may have improved the system). It is of course much mroe effective at preventing ice formation than a boot, since the boot doesn't do diddly until you inflate it...it's a totally reactive answer, while a weeping wing is proactive.

The technical challenge involved in home-brewing such a thing on a canard while still keeping the leading edges smooth would be considerable. Adding TKS-type panels is a a non-starter, since even transverse paint stripes a couple of thousandths thick on the leading edges is a Bad Idea on these airplanes. (This goes to the root of my concern about icing in canards...on a conventional tractor type design, you can stick stuff like deice boots, etc. on the leading edges of the wings and it's no problem. Canards, IIRC according to Burt himself, are much more critical in terms of having stuff on the leading edges of the wings. You have to have clean, smooth airfoils. Please correct me if I'm wrong about this.)

Drilling holes that small yourself is impractical at best and more likely impossible (any of you got a laser that can do that in your basement?).
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  #9  
Old 02-28-2005, 11:19 AM
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Have you seen a canard with all those little thingeys attached near the leading edge that trip the boundary layer into micro turbulence.

Staggered every four or so inches. what are they called?? mmmmmmmm, memory doesn't work so well this morning, they reduce stall speed by 5 or 10 knots and do not change top speed by more than 1 knot or so - look really ugly, but work great.

Price has them on his bird, put them there to break the world altitude record, helped him go to 34000+ feet Normally Aspirated, had 30hp at that altitude in his long.

mmmmmm

adouglass, as i said before, the canard you are talking about does not seem to be the one i am building
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dust

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  #10  
Old 02-28-2005, 11:34 AM
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Quote:
they reduce stall speed by 5 or 10 knots
Yea, I forget the name too. Vortex Generators?

The VariEZ in my hangar has them. I think I read somewhere (ITIRS) that these work well on the old style canard, but dont make a hill of beans difference on ours.
  #11  
Old 02-28-2005, 11:45 AM
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If anyone wants the real skinny on a canard airplane's performance in icing conditions, then you must speak with Carl Denk. He is one of the few canard fliers I know of with actual icing experiences. I'm not talking accidental encounters. I'm talking actual enroute and on approach encounters.

I don't think Carl participates here. You can find him on the Cozy Builders E-mail list (Marc Z's list).
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  #12  
Old 02-28-2005, 01:10 PM
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They're called vortex generators and they're a whole different ball of wax. Their purpose is to re-energize a boundary layer that has become turbulent.

I'm talking about surface contamination at the leading edge, such as might be caused by ice, bugs, or even a transverse paint stripe. Or surface roughness or waviness. We've all seen spam cans with wavy surfaces, dinged up leading edges, etc. etc. etc. and they fly just fine without serious degradation of performance.

I'm sure I've seen stuff about how important it is to get the leading edges of your airfoil clean, smooth and perfect, or degradation of performance will occur.

But this seems to be an area of debate, so I decided to do some digging. I did a couple of searches in my PDF of compiled Canard Pushers and found some references to the importance of having a very smooth canard surface, but they specifically refer to the GU canard. I don't know if the Roncz canard on the MkIV is less susceptible to surface roughness. I also found reference to paint trim on the leading edge tripping the laminar boundary layer and causing speed losses of as much as 11 knots. Tripping the boundary layer on a conventional airplane will have an effect, but not that much. And conventional aircraft do not display any trim change with leading edge contamination (not just rain), which canards do, to one extent or another. This is common knowledge. This might be where I got the idea that canard aircraft are a lot more sensitive to leading edge contamination than spam cans.

But I also found several entries which specifically stated that canards carry small amounts of ice fairly well, with the same caveats that would reasonably apply to conventional aircraft. This was news to me...makes me feel a lot more confident.

I also did a cursory search of some Cozy newsletters and found some icing war stories, but nothing that would lead me to believe that canards are significantly harder to handle in light icing than a conventional aircraft.

I stopped short of searching various other mailing list archives, and because of time did not search all of the Cozy newsletters.

So...I stand corrected.

Anyone have anything useful to add?
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  #13  
Old 02-28-2005, 01:15 PM
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Quote:
Originally Posted by Richard Riley
If both wings suffer an equal loss of lift, there will be no change in pitching moment.

But...but...but...

The canard is more highly loaded than the wing, right? So if it loses (picking a number out of a hat) 20% of its lift and the wing loses 20% of its lift there will be a pitching moment, won't there?

This is where the trim change comes from in the first place, isn't it?
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  #14  
Old 02-28-2005, 01:21 PM
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Quick correction... its not the Canard aircraft that is more suceptable to problems with ice, bugs, pedestrians, etc... its the airfoil chosen for either the canard or wing.

I believe the first airfoil used on the vari and some longs were so critical in design tollerances, that builder errors or contamination of any kind would drastically change the performance.

Okay... back to work!
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  #15  
Old 02-28-2005, 01:58 PM
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Quote:
Originally Posted by Richard Riley
In short, ice on a Long etc is no more a problem than it is on any conventional airplane.
Why thank you Mr. Riley. Important to get the real skinny, I really don't care what airplane someone decides to build, as what I care will not lead to someone to complete the task, they have to really want the particular plane to finish it.

BUT, I want real info for those to make a judgment from.

So the Rule stays the same, icing is bad, but no worse than a regular configuration
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