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Or metal D-section on the leading edge, with series (say, 8 or so) 1/4" Al tubes fastened to the inside to make it an assembly. Of course, you lose laminar flow and performance. You add weight of the plumbing and coolant, etc. You add LOTS of complexity and LOTS of expense and LOTS of failure modes. You carry all this stuff around with you ALL the time. All this fuss and bother to solve a problem that's easy to avoid.

 

We're doing what we do best again ... pole vaulting over rat turds ... Jim S.

...Destiny's Plaything...

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You'd need a system of some sort to force the exhaust gasses through the pipes without changing the back-pressure to the engine, with a fail-safe to ensure that if the system were somehow clogged there would be a way to bypass and vent exhaust normally. Hooking the exhaust directly to a system like that incurs little quirks in back-pressure and compression few people are qualified to deal with. I'd be more comfortable with a system that can be isolated from something as critical as the engine, like a heat exchanger between your de-icer and the cooling system.

Evan Kisbey

Cozy Mk IV plans # 1114

"There may not be any stupid questions, but I've seen LOTS of curious idiots..."

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Make the entire exhaust run through the wing (with mufflers)! No no... make the exhaust the LEADING EDGE of the wing! Hey... if these red-necks around here can turn their exhaust pipes into the shape of a Chevy bowtie, why can't we form the exhaust into the shape of a LE airfoil?

This ain't rocket surgery!

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How about a row of lights in the leading edge. I'm using a 55watt spot light as a taxi light.... and a pitot head heater all at the same time.

 

By the way, it doesnt have to be a lightning storm and ice at the same time. The metal will be there all the time. This way either will get ya. The metal will explode, or the deice system wont work.... that is if you survive the fire from the exhaust igniting you're wings.

I can be reached on the "other" forum http://canardaviationforum.dmt.net

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I forsee jokes about fire extinguishers and field-expedient beer coolers...

 

Of course, we could place CO2 bottles to trigger if the wings catch fire, but that would probably ice them up all over again and we'd be back to square one.

Evan Kisbey

Cozy Mk IV plans # 1114

"There may not be any stupid questions, but I've seen LOTS of curious idiots..."

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About the lightening issus (maybe this should be a new thread....)

 

Isn't there already some metal in the wings? Aileron torque tubes, rudder control lines, copper antennas? Will a lightening strike seek out and destroy these items?

Rui Lopes

Cozy MkIV S/N: 1121

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We got two seperate issues here. Lighning and Ice. There is no cure for lightning except distance (and a storm scope). Forget about trying to embed metal fiber in your glass work.

 

Ice. In the winter when it is REALY cold, you rarely if ever get lightning (not enough vertical buildup for the clouds). Your worst icing conditions (clear ice and rime) is in the spring and fall when temps are near or just below freezing. You can have temp inversions warm/cold layers and water existing in various states. Got to be extra careful.

 

When it gets REALLY cold most of the moisture is in ice crystals. Ice (clear and rime) usually doesnt happen too much if at all. The cloud layers are really shallow too. Usually bases are around 2000 ft and tops about 6000 ft. You need lots of power to quickly get above the clouds if you get some snow build up.

 

I would much perfer to fly in mid winter when it is really cold.

Regards, Nick

___________________________________

Charleston, SC LongEZ, N29TM, 2400 hrs

http://www.canardzone.com/members/nickugolini/

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  • 4 weeks later...

Just as a small update, I planned to do some research into airframe icing accidents, but it seems like Richard Collins has done that and written it up in the January 2003 issue of Flying. Like all his safety related columns it is well researched and the conclusions he reaches seem sensible.

 

His conclusions agree with the sentiments that many expressed on here. Basically it seems that the people getting in trouble in icing conditions are those that have anti-ice systems. The people without them do the sensible thing and don't fly in icing conditions (or get the hell out of it fast).

 

So it seems like this system may not be worth the effort. I am still intrigued however about the embedded tubes acting as a big radiator for auto conversion designs. Anybody know the thermal transfer qualities of epoxy and glass??

 

I guess the big problem is when you are on the ground and there is little/no air going over the airframe to cool things down. Anyway, probably just another half-assed idea that has no merit...

 

Fire away!!

Rui Lopes

Cozy MkIV S/N: 1121

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  • 2 weeks later...

Interview with Burt Rutan...

 

Question:

One of our readers wants to know if you have ever considered directing engine waste heat internally into an airframe to provide anti-icing.

 

Answer:

That's an excellent idea. That could be used, I think, quite nicely on the Boomerang. I would say to the reader: "That's a great idea. Build it. Test it. Develop it. Get it out there so I can use it. Really, I'd love to have that."

 

 

http://www.airandspacemagazine.com/ASM/Web/TWD/Rutan2.html

 

I was only kidding!

:D

This ain't rocket surgery!

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I think making the exhaust pipe the leading edge is the way to go, but it wouldn't be an easy operation, and wouldn't solve the canard problem. I think the Hercules uses this system, bleeding the final stage turbine compressor and routing it into the leading edge, although they lose the equivalent of one motor when it is turned on.

The Coconut King

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<... making the exhaust pipe the leading edge is the way to go ...>

It would probably solve the problem of leading edge ice (would probably trip the boundary layer of your laminar flow wing too). How do you propose to eliminate ice from the rest of the wing?

Help me out here ... Jim S.

 

PS To quote Richard Collins of Flying (via Rui): "... seems that the people getting in trouble in icing conditions are those that have anti-ice systems. The people without them do the sensible thing and don't fly in icing conditions ..."

...Destiny's Plaything...

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I'm about to start building a cozy, and will leave the fancy exhaust leading edge to my MkII. I had an idea to mount the turbo's in the wingtip and have the top of the wing as an intercooler, but am too lazy to work out if the exhaust gases would be useless by the time they travel that far, and doubt if the compression could generate enough heat anyway on the way back.

It would be fantasticaly complicated, so I guess I'll just stay away from ice.

Would having a heated ledge have an effect like a hot knife in warm butter, and create extra low pressure and raise the local speed of sound, or would it just ruin everything? i might be able to tell you in ten years.

The Coconut King

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  • 2 years later...

I have flown Helo's in moderate to severe icing and I can tell you electric systems are anti-ice...and fixed wing boots should be used the same way as anti ice. You should have the hot stuff on way before you encounter it. It is a little freaky standing on the ground and looking at an H-60 with huge junks of ice dropping off the airframe. No matter what system you develop in the world of the "Super Canard" I think the important thing to remember is the prop location and FOD from shedding ice...as the tractor or twin conventional is not at great risk of FOD on the prop from ice shedding. In the case of heated rotor blades and tail rotors if a de-ice fail light illuminates you shut down the system and exit the conditions ASAP. Think of the imbalance a canard would have if the de-ice process did not work equally across the airfoil. I would have to agree with the opinion to stay away and having the system would temp you to go into trace or light and encounter moderate or severe. I have had to fly in it due to mission constraints but otherwise...not so much.

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Howdy all. I'm a lurker and have been reading the anti-ice debate. I just thought I would put in my 2 cents....

 

What about putting a system similar to an auto rear-window 'defrost' between some of the layups on the canard or wing? For the canard in particular, the area is 14.7 sf. The back window of my car is roughly 15 sf. It seems to de-ice pretty quick. Not sure if something like that would work, it is just a thought. Might be feasable just for the canard, or the leading edges of the wing. Not sure how many amps it runs at on my car, but I've never blown the fuse. Yes, I also know that ice conditions in an auto are not as severe as an aircraft. Once again, just a thought.

 

-Blast away! :)

 

-Matt

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Now that is one heck of an interesting idea.

 

It could be worth making a test part to find out

 

a) how hot it gets

b) if the heat generated would have any adverse effect on the structure

c) how much current it draws (the test part would have to be large...at least as large as a canard).

 

This probably would not remove ice buildup, but it could possibly prevent ice formation if switched on ahead of time. It wouldn't do anything for visibility (canopy deice). However, as a save-your-butt device (as opposed to a flight-into-known-icing device) it looks as if it could have real potential.

 

Things to think about:

 

1) Would it work if placed under the standard layup (i.e. between the foam and the leading edge layups) or would it need to be closer to the surface, under its own strip of glass?

2) There isn't a whole lot of flexing going on with the structure, but there is some. Would this survive such flexing?

3) How much weight would it add?

4) Would it alter the stiffness of the airfoil along the leading edge, and therefore alter the manner in which it flexes?

======

Not started yet, maybe never will (currently having an affair with an RV project...shhh...don't tell my set of Cozy plans)....

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According to the FAQ on their web site, the current draw at 12v is 8-16amps, depending on the grid size. I asked them what the max temperature of the heater element was, and they sent me an email back that it was variable, but the max they expect to see is 120F. I little warmer than I would like in the epoxy, but not above it's Tg anyway. I wonder how well Fiberglass/epoxy conducts heat........

I may have to build a test part and try this. The grid is not overly expensive, particularly given the cost of the alternatives.

Mark

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Before you guys get too lost in this, maybe you ought to do some calculations to figure out how much POWER is needed to melt ice electrically over the many square feet of wing area, while moving at 100 - 200 mph through freezing rain.

 

There is some work being done on pulsed systems - do a Google search on:

 

"Electro Expulsive Separation System"

 

and

 

"Ice Management Systems"

 

For some more info, but you're still looking at a LOT of power. I believe that:

 

http://www.airplanedeice.com/home.php

 

these folks are the successor to IMS - they're talking about 100-150 Amp alternators at 50-80V.

 

Plus, you couldn't bury the system under the glass - it has to be able to move.

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It wouldn't be necessary to melt ice over the whole wing surface, just the leading edge, right? Take a look at the Thermawing photo...ice is only melted off the leading edge.

 

Boots only act on the leading edge. Ditto engine bleed air systems.

 

TKS glycol systems bleed fluid along the leading edge and it streams aft...but it evaporates within a few inches.

 

The electro-expulsive thing physically removes ice...it doesn't melt it. Different idea entirely.

 

Interesting thing about the power. That was the big question in my mind.

 

Why would the system need to move, aside from the potential for wire breakage due to airfoil flexing? Same issues as copper foil antennas, no?

======

Not started yet, maybe never will (currently having an affair with an RV project...shhh...don't tell my set of Cozy plans)....

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It wouldn't be necessary to melt ice over the whole wing surface, just the leading edge, right?

Sure, if you don't care if the canard keeps providing lift.

 

Personally, I find this whole notion of anti-icing systems on these planes to be ridiculous, but that's just me.

 

Why would the system need to move, aside from the potential for wire breakage due to airfoil flexing? Same issues as copper foil antennas, no?

No. Did you read the articles about how it works? The electric pulse causes the strips to move apart approximately 0.02". This means the skin of the wing has to be able to expand outward 0.02". This is the motion that causes the ice to crack and break apart. No motion, no ice removal. My copper foil antennae don't move any.
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No. Did you read the articles about how it works? The electric pulse causes the strips to move apart approximately 0.02". This means the skin of the wing has to be able to expand outward 0.02". This is the motion that causes the ice to crack and break apart. No motion, no ice removal. My copper foil antennae don't move any.

Yes, I read it. But I think you're missing the basic idea here. FUBAR's proposal is to put wires in the leading edge in order to HEAT it, in the same way that the rear window of your car is heated.

 

The system you described does not heat the wing. It is designed to do what boots do, specifically to shrug off serious ice accumulation by physically flexing. It's a DE-ice system, not an ANTI-ice system. Doesn't do anything at all to prevent ice accumulation. And if it works like boots, you need to wait until you've got a fair bit of ice for it to work at all (inflating boots before the ice is thick and strong enough to crack won't shed it).

 

The idea of ANTI-ice systems (like the TKS weeping wing system, which doesn't remove ice that's already formed) is to prevent buildup in the first place. Ice forms from the leading edge aft, so if you have a leading edge that's warm, no ice (or more accurately, significantly delayed ice formation...if you're stupid enough to continue flight into severe icing conditions an anti-ice system may get overwhelmed).

 

No anti-ice system I know of treats the whole wing surface, for this reason.

 

Since you're going to get ice on your windscreen at the same time you get it on your flying surfaces, you'll be able to see that you need to get out of there. Such a system would give you time to do what you need to do, which is turn around and get the heck out of Dodge.

 

Such a thing would NOT be suitable for flying into known icing. Neither is the TKS system, IMHO. This is because it's not a DE-ice system. It's also limited by the amount of fluid in the tank.

 

If I were to have something like an electrically heated airfoil, then if there were a CHANCE I'd encounter icing conditions I'd turn it on. I'd NEVER EVER EVER fly into known icing conditions unless in an airplane certificated to do so. I don't have enough money to fly such a plane.

 

The problem with icing, as you'll discover when you get your ticket, is that you don't know you're going to fly into it until you do. The forecasts are spotty at best and pireps are the only thing that provides even halfway reliable information...and they're not very good, either.

 

So: Either don't ever fly in visible moisture when the conditions might allow ice formation at any altitude you might fly at (which is a significant chunk of the year here in the Northeast), or make darned sure you can get out when you do encounter it. That means exit strategies. If you have equipment to help you do it, you're adding a safety margin.

 

You have a point about too much being made of icing. There are lots and lots of people flying airplanes in IMC with no anti-ice/deice equipment, and they do just fine. From the various threads, you may have noted that I was under the impression that ice on your canard was a REALLY big deal, moreso than in a conventional airplane. Subsequent digging revealed a number of reports from qualified individuals that canards can carry a little bit of ice pretty well. So I retracted that assertion, and I feel a lot more confident now.

 

However, there's a caveat. In a couple of hundred hours of actual IMC in the Northeast (flying year-round), I've picked up ice maybe two or three times. Never much of it, so it was never much of an issue. But it DID happen and I DID NOT plan on it. Decide for yourself if you're okay with that happening, and whether you feel the need to do anything about it.

 

The other thing, of course, is that if your wings are icing up your prop might be, too. This is why you should get out of the ice ASAP no matter what equipment you've got. You will have time, but it's limited.

======

Not started yet, maybe never will (currently having an affair with an RV project...shhh...don't tell my set of Cozy plans)....

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