DA-40 Defroster

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vontresc
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DA-40 Defroster

Postby vontresc » Thu Dec 06, 2018 1:58 pm

Last night I went flying in our 2006 DA-40 and was reminded of the poor performance of the pilot's side defroster vent. Now that it is cold again this is more of an issue than in the summer obviously. My current workarouns is to put something over the co-pilot's defroster vent to redirect the airflow to my side. I was wondering if anyone had found a permanent fix to this annoyance?

Thanks
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Re: DA-40 Defroster

Postby Steve » Thu Dec 06, 2018 2:22 pm

Join me in South TX? ;)

I've used the defroster maybe 2 times in 17 years.

Seriously, though, maybe glue a deflector inside the defroster outlet to divert the (meager) airflow more where you need it...


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Re: DA-40 Defroster

Postby briankelly327 » Thu Dec 06, 2018 2:35 pm

Same issue Peter, also a 2006.

I recently built up a pretty thick layer of frost inside the canopy while in flight, but found that by directing the pilot side fresh (cool) air vent up towards the canopy, it slowly helped work away the layer over 10 minutes.

I was also flying solo. Not sure the the plane has defrost power for an extra 1-2 bodies.

Curious about any other workarounds.
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Re: DA-40 Defroster

Postby BkFlyer » Thu Dec 06, 2018 4:53 pm

I encountered this issue on my long IFR training XC with the instructor. To be fair, it was one of the coldest days I can recall, after a blizzard. I was heading home from New Hampshire with the CFI, at altitude it was around -18 to -22C. We had winter coats, defrost heat on blast. Pilot side kept frosting over, but CFIs side was totally fine.

I was able to continually wipe off enough frost to maintain visibility (and it was night). I thought the issue was related to forgetting that one of the winter baffles was removed during a warm front the previous week. Anyway, this is definitely something to be aware of.
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Re: DA-40 Defroster

Postby Rich » Thu Dec 06, 2018 6:15 pm

One trick I've heard of: If you don't have anyone in the rear seats, plug the rear seat heat vents in whole or part, with old sweaters or something, forcing more airflow though all the other heat vents.
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Re: DA-40 Defroster

Postby BkFlyer » Thu Dec 06, 2018 10:32 pm

Rich wrote:One trick I've heard of: If you don't have anyone in the rear seats, plug the rear seat heat vents in whole or part, with old sweaters or something, forcing more airflow though all the other heat vents.


Great idea 8-)
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Re: DA-40 Defroster

Postby Rich » Thu Dec 06, 2018 10:48 pm

Rich wrote:One trick I've heard of: If you don't have anyone in the rear seats, plug the rear seat heat vents in whole or part, with old sweaters or something, forcing more airflow though all the other heat vents.


Disclaimer: I've never tried this so I don't know how effective it really is, but seems rational.

I've not seen this particular problem with the defroster. I get slightly more airflow on the pilot side than copilot. I now wonder if there isn't a design difference between the instrument cover on my pre-G1000 plane vs. the more common post-2004 planes. On mine there are two sets of defroster vents across the front and would likely produce an interesting interference effect. There might also be something going on with how much the defroster vs. floor heat controls are balanced in different aircraft. (Of course those lower heat vents are amazingly small. They remind me of my old MGB's almost useless heating/defrosting system :roll: )
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Re: DA-40 Defroster

Postby Lou » Fri Dec 07, 2018 2:40 am

I fly a lot in the cold. When I took off this morning it was -16C (although it was only -6C at 5500' - typical). I find that once the engine gets to operating range, the defroster works pretty well. You have to use the cold air baffle. You also need to lean aggressively to get the highest CHT to 380, and try to get the oil above 170, although it won't go much above. But since it's impossible to do this on the ground, you are scraping for the first few minutes. ( I remember driving a Honda Civic in the 1970's: you steered with one hand, shifted with the other, and scraped with the other.) And yes, the pilot's side is worse.
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Re: DA-40 Defroster

Postby Steve » Fri Dec 07, 2018 2:59 am

Lou wrote:I fly a lot in the cold. When I took off this morning it was -16C (although it was only -6C at 5500' - typical). I find that once the engine gets to operating range, the defroster works pretty well. You have to use the cold air baffle. You also need to lean aggressively to get the highest CHT to 380, and try to get the oil above 170, although it won't go much above. But since it's impossible to do this on the ground, you are scraping for the first few minutes. ( I remember driving a Honda Civic in the 1970's: you steered with one hand, shifted with the other, and scraped with the other.) And yes, the pilot's side is worse.


Lou:

Since our heat/defrost air comes from a shroud around the muffler, I'm not sure that either oil temperature or CHT has anything to do with how warm the supplied air gets. Maybe EGT (indirectly). It is just an inadequate system for environments with a lot of cold weather. I understand that the Powerflow system is slightly better, but I have the original design exhaust system...

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