Ice Bridging

Sorta related question.

On the King Air we have heated cowl inlets from the exhaust being routed around the ring and out the other side. Why is it so difficult to continue routing it down the wing?
 
Cessnaflyer said:
Sorta related question.

On the King Air we have heated cowl inlets from the exhaust being routed around the ring and out the other side. Why is it so difficult to continue routing it down the wing?
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Heating the wings adequately would require quite a bit more bleed air, not sure that the PT6 has that much extra.
 
SpiraMirabilis said:
You say there is a limited amount of time you can use TKS, sure... but there is an even more limited amount of time you can use boots in icing. Have you ever been in constant icing for 40+ minutes in a caravan with boots that you can blow an unlimited amount of time? I bet you would be happy to trade them for the 2-3 hours you can get out of TKS at that point.

My experience in the caravan is that everytime you blow the boots it is a little bit less effective than the last time.
Sent from my SPH-D700 using Tapatalk
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exactly! having not flown the booted ones in icing, and now that we have all but 2 planes in base with TKS i don't want too. the tks is cleaner overall, if you do build some ice you don't lose speed. overall it seems to be the perfect system for a 208
 
I am not an engineer but I would imagine that the gases would cool before they got to the end of the wing, especially at low power settings, rendering the system ineffective. At high power settings the exhaust gasses may become pressurized in the wing, causing other problems. I imagine it would be pretty complicated to rig an exhaust bleed off valve like they have for the bleeds of most aircraft
 
For some of those that don't fly jets, there's often a minimum power setting that the bleed system needs to operate effectively.

Even in big jets, well, not big like Alchemy's and Polars, but you absolutely do not go casually milling about with moderate and ESPECIALLY severe icing because you've got decent ice protection.

The Beech 1900D had an awesome system and thank goodness because up in the midwest, you were lookin' and crackin' all the darned time. But if it was moderate, later skater, we're climbing or descending out of it because if your system fails, you've just painted yourself into a corner and you begin to run out of options quickly.

I'll be the wuss-boy getting above or below it and save all of the studs for slogging around in it.
 
PT6's (or any other turbine really) are very sensitive to exhaust back pressure. Ducting the majority of the exhaust down a wing would create HUGE losses in efficiency. And unless you have a turbo prop over about 3K in shaft horsepower, there wont be enough bleed air either.
 
Doug Taylor said:
For some of those that don't fly jets, there's often a minimum power setting that the bleed system needs to operate effectively.

Even in big jets, well, not big like Alchemy's and Polars, but you absolutely do not go casually milling about with moderate and ESPECIALLY severe icing because you've got decent ice protection.

The Beech 1900D had an awesome system and thank goodness because up in the midwest, you were lookin' and crackin' all the darned time. But if it was moderate, later skater, we're climbing or descending out of it because if your system fails, you've just painted yourself into a corner and you begin to run out of options quickly.

I'll be the wuss-boy getting above or below it and save all of the studs for slogging around in it.
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Teller and I got stuck with no pressurization in the NE one winter. We were in what I would call the worst Ice i've ever seen. We couldn't climb above it, and honestly, buy the time we got up to 9-10k feet, we were only doing 500fpm. best forward speed was 180kts or so if I remember. While we tried multiple different altitudes, nothing was helping. We had ice formatoins as far back as I could see on the engine nacels, well aft of the boots, and all over the winglets. I was spending more time hitting the auto swithch than flying the plane, and every cycle was poping a lot of clear off. PWM approach knew something was up. GS/ frequent altitude requests must have done it, but, they offered up block altitudes for us. We tried everything from 3k feet to 10, and were pretty much screwed. It didn't seem funny at the time, but, we had no guidance for appraoch speeds after severe icing etc. On the way into boston, we were looking at 6in of ice on the winglets, fully glazed spinners, and chunks of ice on top of the wings. We ballparked that we were going to add 20kts to ref, and wave off if we felt any unusuall vibrations, pitch movements etc. held our breath a bit as we put out flaps.. I've seen a lot in the 1900 but, this scared me.

Post this event, I will not take an altitude restricted airplane into forcast or reported icing condtions greater than light, unless I have a really clear picture of what I'm looking at. We only had maybe 4 people in the 1900? The plane was a truck, it could take ice left and right... but, when you exceede the capabilities of it's ice protection, it's no better than flying a 172 into ice..

but, we didn't have any issues with bridging :)
 
Itchy said:
PT6's (or any other turbine really) are very sensitive to exhaust back pressure. Ducting the majority of the exhaust down a wing would create HUGE losses in efficiency. And unless you have a turbo prop over about 3K in shaft horsepower, there wont be enough bleed air either.
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I can't imagine the minimum power settings for deice on a hot winged pt6... I'm not sure that you could descend or land for that matter...
 
Itchy said:
PT6's (or any other turbine really) are very sensitive to exhaust back pressure. Ducting the majority of the exhaust down a wing would create HUGE losses in efficiency. And unless you have a turbo prop over about 3K in shaft horsepower, there wont be enough bleed air either.
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Yeah I guess I didn't think of the basic function of an engine is acting like an air pump. It just works so nicely on the cowls :) On another tangent has anyone flown with the Cessna 400's hot wings?
 
Consider the PT-6 like a kid blowing a geared pinwheel.

Can anyone name the original intended purpose of the PT-6A? Class? Class? Beuhler?
 
Yeah. A non-pilot friend told me they have a few here for microsofts power backups. They are tested a few times a month and they have to be running at 100% in three minutes or less before the battery backups are out of juice.
 
Cessnaflyer said:
Yeah. A non-pilot friend told me they have a few here for microsofts power backups. They are tested a few times a month and they have to be running at 100% in three minutes or less before the battery backups are out of juice.
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The PT6 might be the only thing beyond Tim Teebo that will run on a hope and a prayer.
 
mikecweb said:
The FAA and NASA claim that one of the reasons that ice bridging isn't a concern anymore is due to new boot design. Problem is we're still flying around aircraft with old boot designs. TKS i think is smart for props. For jets like the Hawker it's moronic. I never had a problem with it but I've never had a problem with any heated wing either.
I've seen ice bridging in the Metro and Baron.
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What I understand is that the old boot design was when the whole boot would inflate at once without any ridges in the boot. From what I understand, there are no aircraft that uses this design anymore which is why NASA and the FAA says everyone has the new boot design. Am I correct here?
 
Fly_Unity said:
What I understand is that the old boot design was when the whole boot would inflate at once without any ridges in the boot. From what I understand, there are no aircraft that uses this design anymore which is why NASA and the FAA says everyone has the new boot design. Am I correct here?
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My boots have ridges and I was cursing up a storm yesterday trying to climb through moderate mixed as I watched the boots just bridge instead of blow the ice.
 
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