Flying Through Rain

Velocity173 said:
View attachment 71321 Another anomaly for the canard guys is pitch instability in rain. Some don’t have it, some do. Just flew through light rain on Friday and soon as it hit, my nose pitched down a couple of degrees. A little annoying but once established and retrimmed in the rain, it’s a non event. It’s the in and out that’s the problem. Made for a pretty flight.
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I would never have thought about that. Very interesting.

Dan Thomas said:
Carb ice is more likely in rain. Can't have all that water in the air without the relative humidity going up.
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What are these "carburetor" things you speak of? ;)
 
Ted DuPuis said:
I would never have thought about that. Very interesting.



What are these "carburetor" things you speak of? ;)
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Yep, you can see in some of these comments that the phenomenon isn’t universal. Depends on the type canard. Not dangerous or anything but something to anticipate when entering rain.

http://www.ez.org/smf/index.php?PHPSESSID=5s41sjjroacen5oek5hc416b34&topic=338.0

There’s a Varieze vid “Race 20” where the guy flew a low pass over the lake by Oshkosh and picked up a bunch of bugs. When he pitched up and started to slow down, the nose started porpoising because of the canard stalling. Think he had to land at over 160 mph at OSH.

So yeah, with such a heavily loaded airfoil and contributing to around 20 % overall lift, surface contamination can produce some unusual characteristics. One of these days I’m going to put some tufts on my canard, go fly in some rain and see what’s going on.
 
Ted DuPuis said:
What are these "carburetor" things you speak of? ;)
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They're the 1930s tractor technology most of us have to put up with. Along with bias-ply tires, felt grease seals on the wheel bearings, and magnetos. Us old guys feel comfortable with stuff as old as we are:rolleyes:

How do guys in their 20s feel about flying airplanes three times as old as they are?
 
Remind me again why pressure carburetors are not a more common sight in our hobby? Are they more complicated/expensive to implement than fuel injection?
 
Tantalum said:
A plane like a Cirrus seems to be more "direct" with the air inlet up in the cowl and piping its way through the turbos / engine, with no carb and no drain that I've found when the cowl's been off. The alt air on a Cirrus is "automatic" it just flips open with a magnet, so.. hope for the best in rain I guess?? #parachute ?

It has happened to jets though, right? So it seems the possibility exists

Would be interesting to put one up in one of those turbine test stands and see how much water it takes to kill
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Most of the time you can't kill the engine with water; some have been tested with flows beyond any recorded in nature.
 
hindsight2020 said:
Remind me again why pressure carburetors are not a more common sight in our hobby? Are they more complicated/expensive to implement than fuel injection?
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Some of the early 310s used pressure carbs. The Bendix fuel injection systems that Lycoming used were described as "a pressure carburetor with individual cylinder distribution and particularly good resistance to icing" if you look back in some of the technical documentation.

Big reason I think has to do with the inherently uneven mixture distribution of carbs in any form and thus how rich you need to be for detonation resistance at high power settings.
 
Ted DuPuis said:
Some of the early 310s used pressure carbs. The Bendix fuel injection systems that Lycoming used were described as "a pressure carburetor with individual cylinder distribution and particularly good resistance to icing" if you look back in some of the technical documentation.

Big reason I think has to do with the inherently uneven mixture distribution of carbs in any form and thus how rich you need to be for detonation resistance at high power settings.
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So I assume then it's closer to the complexity of a mechanical fuel injection system, to the degree that it's not economic to implement compared to float carbs, especially if you're still gonna get the crappy fuel distribution of carbs. I'd figure the icing resiliency alone would be a big improvement over the float carbs to make it worth the while.

Wish there was a cheaper way of retrofitting these spam cans with economical fuel injection. Another EXAB FTW case study I suppose.
 
hindsight2020 said:
So I assume then it's closer to the complexity of a mechanical fuel injection system, to the degree that it's not economic to implement compared to float carbs, especially if you're still gonna get the crappy fuel distribution of carbs. I'd figure the icing resiliency alone would be a big improvement over the float carbs to make it worth the while.

Wish there was a cheaper way of retrofitting these spam cans with economical fuel injection. Another EXAB FTW case study I suppose.
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That's my understanding. Plus as they moved to bigger engines, the benefits of fuel injection were greater. Remember that we look at these things as "cheap old planes" but when they were new they were the equivalent of any new airplane that you and I can't afford. So, the technology was what fit that market need at the time.
 
Ted DuPuis said:
That's my understanding. Plus as they moved to bigger engines, the benefits of fuel injection were greater. Remember that we look at these things as "cheap old planes" but when they were new they were the equivalent of any new airplane that you and I can't afford. So, the technology was what fit that market need at the time.
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What's interesting about that statement of course, is that the new airplanes still come with this anachronistic technology installed (Piper still rolling O-360s out the Vero Beach floor). Which begs the question, what's up with new pricing then. The latter is a rhetorical point of course, we all understand the death of the hobby by lack of volume, and the lack of ROI in implementing technology advances due to litigation as the National Sport.
 
Most lawn and garden equipment have pressure/diaphragm type carbs so they can operate at any orientation. Those aren't very expensive, although there would not be any advantage for most standard air application
 
hindsight2020 said:
What's interesting about that statement of course, is that the new airplanes still come with this anachronistic technology installed (Piper still rolling O-360s out the Vero Beach floor). Which begs the question, what's up with new pricing then. The latter is a rhetorical point of course, we all understand the death of the hobby by lack of volume, and the lack of ROI in implementing technology advances due to litigation as the National Sport.
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Yes, I figured that would be the logical follow-on to that.

Basically there's an intersection of technology, wants/needs, money, and FAA certification. Back in the 50s and 60s, FAA certification was a much lower hurdle than it is today, and the sales were much higher. So an "advanced" mechanical fuel injection system provided operational benefits while being pretty easy to certify and not cost prohibitive.

Now certification is a lot harder and a lot more expensive, especially for electronic engine controls. I spent 5 years doing this so I know of what I speak. Sales numbers are lower, and the reality is that the wants/needs are still handled mostly fine by mechanical setups.

The real reason cars went electronic was emissions, and piston aircraft don't have any emissions regulations. That would force the hand of manufacturers, but it would probably add $100k per plane.
 
1RTK1 said:
Most lawn and garden equipment have pressure/diaphragm type carbs so they can operate at any orientation. Those aren't very expensive, although there would not be any advantage for most standard air application
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When it comes to airplanes, I would say icing resiliency would be huge advantage over float carbs, beyond the obvious aerobatic orientation benefits. Induction icing is my #1 grievance against float-carbs. Poor induction balancing I'm rather willing to live with by comparison, at these fully depreciated price points anyways.
 
Oh, they still can ice no matter what marketing says, or at least the ones I have played with.
 
I fly a Cirrus sr 20, been trough some "yellow" radar return rain, relatively heavy, never and issue with the engine. The biggest thing is the cruise speed slows by about 10 knots in rain. The 20 has an alternate induction air door that is manually actuated from inside the cockpit.
 
PaulS said:
I fly a Cirrus sr 20, been trough some "yellow" radar return rain, relatively heavy, never and issue with the engine. The biggest thing is the cruise speed slows by about 10 knots in rain. The 20 has an alternate induction air door that is manually actuated from inside the cockpit.
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Interesting. I’ve never had a noticeable speed decrease in rain more than a few knots at most. Thanks for sharing that.
 
Ted DuPuis said:
Interesting. I’ve never had a noticeable speed decrease in rain more than a few knots at most. Thanks for sharing that.
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I believe it's due to the laminar wing design on the Cirrus, at least that is what I've been told.
 
PaulS said:
I believe it's due to the laminar wing design on the Cirrus, at least that is what I've been told.
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That came to my mind, along with the fixed gear adding places for the rain to hit.
 
PaulS said:
I believe it's due to the laminar wing design on the Cirrus, at least that is what I've been told.
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I've heard about the Cirrus wing slowing down significantly in rain too for the same reason. However, the Mooney has a laminar flow wing and doesn't slow down noticeably, so the question becomes "how laminar is laminar?"
 
people throw the words laminar too liberally. Hell, my wobble leg Cherokee airfoil is technically "laminar". That and a buck twenty gets me a cup of coffee.... :D
 
Ted DuPuis said:
Remember that we look at these things as "cheap old planes" but when they were new they were the equivalent of any new airplane that you and I can't afford.
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Not much change there. When I learned to fly in 1973, the price of a new 172 was $23K, the same price as a new house in my hometown. The price of a new (relatively equivalent) house there now is well over $500K, maybe as much as $600K. Adjusting some for an overheated real estate market, that house still costs about the same as the new 172. Sure, the house is better built and more efficient, but the 172 has G1000 and leather and other stuff, too.
 
The only flight conditions I could picture causing that much water intake, the engine quitting would be the last of your worries.

 
Maybe that's why my instructor was adamant about always landing on the center line
 
James331 said:
The only flight conditions I could picture causing that much water intake, the engine quitting would be the last of your worries.

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I had never heard that. What a story. It's amazing he survived.
 
That William Rankin story is nuts, I remember hearing about that once in a CAP meeting. Insane stuff

PaulS said:
I fly a Cirrus sr 20, been trough some "yellow" radar return rain, relatively heavy, never and issue with the engine. The biggest thing is the cruise speed slows by about 10 knots in rain. The 20 has an alternate induction air door that is manually actuated from inside the cockpit.
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Interesting, the SR22TN I fly has a magnetic automatic alternate air door.. so no way to use it from the cockpit. And it also slows down in the rain.. I was surprised actually what a big impact turbulence has on the speed too.. it makes sense, but I don't recall other, granted slower, planes I have flown on be that sensitive to speed in the bumps. Heck even having the FIKI on seems to take 1-3 knots off
 
Tantalum said:
Interesting, the SR22TN I fly has a magnetic automatic alternate air door.. so no way to use it from the cockpit.
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We have an IO-550 in the Mooney as well, and we have both the auto (magnetic) door as well as a knob we can pull to manually actuate it. Kinda surprised Cirrus didn't include that.

And it also slows down in the rain.. I was surprised actually what a big impact turbulence has on the speed too.. it makes sense, but I don't recall other, granted slower, planes I have flown on be that sensitive to speed in the bumps. Heck even having the FIKI on seems to take 1-3 knots off
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The FIKI thing makes perfect sense, since you're introducing fluid onto the leading edge of the airfoil, much like flying through rain but probably a bit less so. ;)
 
flyingcheesehead said:
as well as a knob we can pull
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We like as few knobs as possible.. hell, even having a mixture controls seems like some kind of peasant joke

flyingcheesehead said:
FIKI thing makes perfect sense, since you're introducing fluid onto the leading edge of the airfoil
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For sure.. makes you appreciate the work the wing is doing out there. When you do all your training in beat to hell Cherokees and Skyhawks missing wheel pants, paint flaking, years worth of dead bugs all over it, thumb sized rivets sticking out all over the place, etc., you don't realize what impacts these things have. Now get a meticulously clean airplane, and you hit some rain and down your speed goes 10 knots!
 
Tantalum said:
For sure.. makes you appreciate the work the wing is doing out there. When you do all your training in beat to hell Cherokees and Skyhawks missing wheel pants, paint flaking, years worth of dead bugs all over it, thumb sized rivets sticking out all over the place, etc., you don't realize what impacts these things have. Now get a meticulously clean airplane, and you hit some rain and down your speed goes 10 knots!
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I used to say that the Aztec was so good in icing because its aerodynamics were so poor it was impossible to make them worse.

Worst I ever lost for IAS was 10 MPH in mixed icing. Went from LOP to ROP and got my 10 MPH back.

The 310 and 414 lost it a lot quicker, but removing excess antennas reduced that slowdown significantly.
 
Tantalum said:
We like as few knobs as possible.. hell, even having a mixture controls seems like some kind of peasant joke
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So what you want is an iPlane? :rofl:

There's certainly something to be said for that, but my CFII pointed out on my most recent flight review that for the magnetic door trip to happen, you need a significant restriction in airflow for it to get sucked open, meaning that without using the knob you may be stuck in a very undesirable partial-power situation. It'll certainly keep it from quitting entirely, but if it happened in the wrong time or the wrong place... I guess I'm still kinda glad I have the knob available.
 
flyingcheesehead said:
for the magnetic door trip to happen, you need a significant restriction in airflow for it to get sucked open
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Yeah, when we had the cowl off last I was surprised how much force it required to pop that door open!

I was mostly kidding about the knobs.. but some of these things do seem a bit anachronistic

..open the pod bay doors hal
 
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