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  #1  
Old 01-02-2008, 03:28 PM
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Default Safety versus performance

Last year, so a buddy tells me that read the nall report, 44 died from carb icing. why, cause it is simple, we trade take off performance for safe performance.

I know, I know, just add carb heat and the problem is solved - but 44 are dead

Does it really matter that we lose a little performance, are people flying from short runways?? Do they really need that extra little bit of performance.

Does it change climb, or cruise.

If it caused 44 fatalities, then it also caused 100's of other airplane accidents that were not fatal.

We need to stop trading performance for safty, we need to be just plane safe.

If you are putting a carb on your plane - put in carb heat and leave it on, no off position or put in fuel injection for no carb icing

Safe systems create safe flying
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  #2  
Old 01-03-2008, 08:38 AM
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Default Re: Safety versus performance

Knowlege is safety. Carb heat on makes your plane perform like total crap in some instances. Leave it on all the time and you may be looking at a repair bill. Best thing is know your weather. Period. Barometric pressure close to temp creates carb ice. Nothing to do with sacrifice. Piloting knowlege is key.
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  #3  
Old 01-03-2008, 09:27 AM
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Default Re: Safety versus performance

Repair bill - our cars have always had carb heat on - no repairs - no icing
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  #4  
Old 01-03-2008, 11:00 AM
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Default Re: Safety versus performance

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Originally Posted by Dust View Post
Repair bill - our cars have always had carb heat on - no repairs - no icing
I don't now about you, but every car I've owned in recent memory has fuel injection of some kind (TBI or full EFI). Throttle plates don't need carb heat, and the coolant lines to my intake manifolds are only for emissions. Give me EFI, an IAC solenoid and a throttle plate and I'll never think about carb ice again.
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  #5  
Old 01-03-2008, 11:22 AM
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Default Re: Safety versus performance

Yes - i agree - as i said fuel injection solves the problem - cars with carbs had carb heat all the time

I personally think it is silly to put a carb in an airplane and all manufacturers should have stopped the practice eons ago

I just look at the facts and last year 44 people died from carbs, simple as that
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  #6  
Old 01-03-2008, 09:24 PM
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Default Re: Safety versus performance

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Originally Posted by Dust View Post
Yes - ...cars with carbs had carb heat all the time.
Not completely true Dust. Yes there was carburetor heat, but only when the engine is cold. If you look at the air cleaner housing, there's a thermostat controlled bellow in there that open and close a flap. When the engine is cold all the intake air is from the heat box on the exhaust manifold. When the engine is hot, that flap close and all the air is directly from "outside" which does improve the performance of the engine. Of course "outside" varies from car models to car models.

Some cars just pull the "outside" air from under the hood, other cars have a duct to pull the outside air directly from the exterior of the engine compartment.

When it's really cold and wet, the flap would be between the two pulling air from both.

One notable exception I can think off right now is the VW bug air cooled boxer, where a small pipe direct part of the exhaust from one side and out the other side heating up the intake manifold and the attached carburetor. The intake air though, is not directly heated.
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  #7  
Old 01-03-2008, 10:03 PM
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Default Re: Safety versus performance

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Originally Posted by WileEZ View Post
Not completely true Dust. Yes there was carburetor heat, but only when the engine is cold. If you look at the air cleaner housing, there's a thermostat controlled bellow in there that open and close a flap. When the engine is cold all the intake air is from the heat box on the exhaust manifold. When the engine is hot, that flap close and all the air is directly from "outside" which does improve the performance of the engine. Of course "outside" varies from car models to car models.

Some cars just pull the "outside" air from under the hood, other cars have a duct to pull the outside air directly from the exterior of the engine compartment.

When it's really cold and wet, the flap would be between the two pulling air from both.

One notable exception I can think off right now is the VW bug air cooled boxer, where a small pipe direct part of the exhaust from one side and out the other side heating up the intake manifold and the attached carburetor. The intake air though, is not directly heated.
Both my '78 Chevy Nova and '74 260Z had a heat duct from an exhaust muff to the air cleaner, both controlled via a temperature controlled baffle.

Also, I really hope you don't fly/taxi around with your carb heat on, the carb heat bypasess the air filter and can let contamination in.

Also in my humble opinion, having maximum power at take off is a safety issue. You really want to climb at the greatest rate to get yourself to a safe altitude as soon as possible.
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  #8  
Old 01-03-2008, 11:46 PM
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Default Re: Safety versus performance

Quote:
Originally Posted by mfryer View Post
Both my '78 Chevy Nova and '74 260Z had a heat duct from an exhaust muff to the air cleaner, both controlled via a temperature controlled baffle.

Also, I really hope you don't fly/taxi around with your carb heat on, the carb heat bypasess the air filter and can let contamination in.

Also in my humble opinion, having maximum power at take off is a safety issue. You really want to climb at the greatest rate to get yourself to a safe altitude as soon as possible.
Well, if the air filter is bypassed with carb heat on that is just poor design, blows my mind that pilots have accepted this just for a little extra performance!

If you are on a runway and have conditions that require more power than a heated intake can provide, simple, do not use that runway.

The air delivery system to the airplane engine should be bullet, i mean pilot proof.

Don't use aviation sense, use common sense and read the accident reports. Design systems that do not allow simple mistakes to kill you. carb heat, fuel that can be pumped overboard if you forget a pump on. oiless vacuum pumps that fail every 400 to 600 hours. magnetos that have a short life compared to modern electronics. electrical connections that are not stress relieved. Stainless used where spring steel is appropiate. understand the materials and systems and design out "you gotta remember" and be safe
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  #9  
Old 01-03-2008, 11:51 PM
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Default Re: Safety versus performance

Quote:
Originally Posted by Dust View Post
Yes - i agree - as i said fuel injection solves the problem - cars with carbs had carb heat all the time
Not flying a plane solves the problem too.
Quote:
I personally think it is silly to put a carb in an airplane and all manufacturers should have stopped the practice eons ago
Possibly. Carbs are safe given check lists and skill sets. Might have something to do with recertification of a plane certified for a carb too. I understand that yellow tag (or whatever it's called. STC?) can be worth thousands.

Or another way, what do you think a Cozy would cost the end user if Piper made it?

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  #10  
Old 01-04-2008, 04:00 AM
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Default Re: Safety versus performance

Quote:
Originally Posted by Dust View Post
...blows my mind that pilots have accepted this just for a little extra performance!
Not so little, carb heat on can decrease engine performance as much as 15% to 20%! In a 180 HP engine that is about 27 to 36 HP lost.

The chart below shows when icing is most likely to happens. (From http://www.faa.gov/ats/afss/newyork/ENROUTE.htm)

However while the FAA article speaks of winter flying, icing condition can happens in the middle of summer. It pays to watch the weather reports and look at the dew point.

Best way to deal with this, is to educate yourself and if you feel the need to turn on the carb heat, leave it on! Wait until you get to where icing is less likely to happen (climb to attitude) then turn it off, don't turn it off just because the engine seems to be doing better.

Google "carburetor heat performance", there's lots of information about carb heat, icing and how to avoid and deal with it.
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  #11  
Old 01-04-2008, 10:06 AM
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Default Re: Safety versus performance

Quote:
Originally Posted by WileEZ View Post
Google "carburetor heat performance", there's lots of information about carb heat, icing and how to avoid and deal with it.
I completely understand the methods of dealing with carb icing, i'm sure the 44 dead also did! I'm also sure the hundreds of others that had accidents understood it.

But the continual mantra of train, train train, should be replaced with better systems. Simple as that, we should not accept the mantra in lieu of better systems.

Interesting to find out that on every landing i have no air filter cause on every landing, even in arizona, i use carb heat.

Best solution for not using carb heat is to have fuel injection.

To repeat a story, a few years ago i went to the ntsb or faa, forget which has the database, site to research wing icing, could not find ANY incidents cause of all the carb icing reports that popped up.
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dust

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  #12  
Old 01-04-2008, 05:14 PM
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Default Re: Safety versus performance

Quote:
Originally Posted by mfryer View Post
Both my '78 Chevy Nova and '74 260Z had a heat duct from an exhaust muff to the air cleaner, both controlled via a temperature controlled baffle.

I think these systems are just for getting heat to the carb to allow it to warm up quicker. If your nova has the V8 you will find that there is a exhaust bypass built into the intake that will have heat under the carb all the time. That is if you haven't installed an aftermarket intake that does away with the heat bypass.
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  #13  
Old 01-05-2008, 12:26 AM
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Default Re: Safety versus performance

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Originally Posted by dirtdox View Post
I think these systems are just for getting heat to the carb to allow it to warm up quicker. If your nova has the V8 you will find that there is a exhaust bypass built into the intake that will have heat under the carb all the time. That is if you haven't installed an aftermarket intake that does away with the heat bypass.
I don't mean to get off topic, that being said, it was a 305 v-8, all stock. I do not recall (I sold the car in 90) any sort of exhaust bypass, but I to remember the little duct from the exhaust manifold to the cleaner. Frankly I cannot think of any experience that I or any one I know of having automobile carb icing problems, but just last weekend the car talk guys were talking about that on a Honda.

I think I sort of understand Dusts aversion to the system, but the topic is a little more complex then stated. Also nothing can replace good training.

I personally would like to have the ability to fly any well maintained aircraft that I can fly. I will probably begin tailwheel transition in a J-3 this summer. The landing gear design is not nearly as safe as a tricycle configuration, however, it will be fun, and no doubt I will probably be a better pilot for it.
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  #14  
Old 01-07-2008, 09:53 AM
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Default Re: Safety versus performance

Quote:
Originally Posted by mfryer View Post
I think I sort of understand Dusts aversion to the system, but the topic is a little more complex then stated. Also nothing can replace good training.
Well, i just love learning a subject. I was chatting with an a&P OVER THE WEEKEND and he agreed that carb icing is silly and mentioned that pipers rarely have carb ice problems as they put the air intake near the exhaust.

Probably why your nova did not have ice problems - the air in the engine compartment is slightly warmed up.

We as aviators should simply not accept dangerous conditions. the current carb heat systems are not meant to stop ice from forming but to quickly melt any that does form, that is why they rob so much power.

The honda probably runs into a problem as the air is ducted from outside of the engine compartment and does not add enough air from the hot exhaust manifold to prevent ice.

I don't know how to perfectly design a system to prevent ice, imagine it would take some kind of temp controlled spring on a vent to allow hot air from the manifold to be mixed with outside air.

Just make it simple, use fuel injection and don't forget to have a backup pump and a backup electrical system and plenty of pleated fuel screens with pressure overflows.

And again, i agree on training, but, design the plane so that the minimum must be trained for. Engineer out "you gotta remembers" and save lives.

As far as what is dangerous and what is not - just go to the accident logs and look for reality, not what you are told is reality.

If it can go wrong - it will. warning horns do knot work, memory does not work. if you can make it automatic - do it.

if you can get carb icing, you will

if you can forget a pump on and pump fuel overboard - you will

if you can leave the gear up - you will

If you can over-boost - you will

If a connection is just soldered and/or crimped and not stress relieved it can fail - it will

if a belt can break - it will

If you can make a backup that is automatic - make it

If you can hit a wing tip on take off or landing - you will

If you can hit the prop on takeoff or landing - you will
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  #15  
Old 01-07-2008, 01:48 PM
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Default Re: Safety versus performance

Well, I tell ya' if I find a great price on a carbureted 360 I'm gonna' buy it. I want to fly and if the price is right its no problem adding carb heat when necessary. I'll definetly go F.I. if that's the plan but I'm not afraid.

Did all 44 die from carb icing at takeoff? I used to fly a 152 and if the carb heat was on at takeoff on a hot summer day the sucker would sputter, shake, and complain. I never did find out if I couldn't make the length of the runway but I wonder if there's any accidents with the carb heat left on?

Last edited by neverquit : 01-08-2008 at 08:02 AM.
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