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  #16  
Old 01-08-2008, 12:25 AM
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Default Re: Safety versus performance

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Originally Posted by Dust View Post
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
Dust, I respectfully disagree. While I admire your caution, something that is valuable in our en devour of building and flying aircraft, i think it is a little to broad brush in this case.

If something can go wrong, it MIGHT. Not WILL. My first instructor had over 10,000 hours instructing in J-3 cubs, Cessna 150s and 172s, and doubtless more with no accidents. His flying career ended ironically in the fog, when a hung over student hit him while cycling to work. I doubt I will be so lucky.

(If a drunk student can hit you on your bike - he will)

He didn't have any prop strikes, wingtip strikes, gear up landings, carb heat engine failures etc.

Those things do happen, and we should do what we can to prevent them. However, while carbureted engines CAN experience carb icing, there is a back up, and that is the carb heat system. It should be tested at engine run-up and used as prescribed in the POH.

I personally have experienced carb icing a couple of times. Fortunatly I had a CFI onboard both times, but they did not intervene. They let me discover the problem (a slight drop in RPM over time), and I remedied the situation by applying carb heat. That is what training is all about. Would I fly in December with visible moisture again (at night no less)? No. I would not risk it. Also at any point in during the flight an emergency landing site should be picked out, another important part of this equation.

Aircraft have many systems that we should learn and use, any system can fail, there should be an understanding of the system, how it works and what do do in case of a failure.

I guess Dust, that while that aircraft carburetor systems are not perfect, I don't feel quite as uncomfortable with them as you. I will however, if I do go with a carb, to make sure that the heat system is functional and properly designed.

One last note it that to be sure, if we do not want an aircraft accident, we simply don't fly. For me, that is an option, but not one I relish.
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  #17  
Old 01-08-2008, 09:56 AM
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Default Re: Safety versus performance

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Originally Posted by mfryer View Post
One last note it that to be sure, if we do not want an aircraft accident, we simply don't fly.
heh heh heh - cmon - how come when talk goes to safety it is suggested that i just don't fly!

Talked to a long driver last evening, he swears that he is committed to safety and thinks carbs are just fine.

Then he told me of a time in florida when he gets ice, even with the carb heat turn on, so thick in the carb he losses the engine. Makes it to an airport and goes in for a cup of coffee.

1/2 hour later he checks the carb - still full of ice. He still thinks carbs are fine!

the "it won't happen to me syndrome" gets people killed.

Would you accept this kind of performance from your car?

Lets train for real safety and design out the extra burdens and dangers.
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  #18  
Old 01-14-2008, 12:18 PM
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Default Re: Safety versus performance

Talked to a vari plot the other night - he has never lost an engine to carb ice, but, his hangar mate flew 150's allot and would regularly get carb ice and use the carb heat to solve the problem.

Except once - it did not work and he lost engine power. he was lucky, landed in the winter on a harvested corn field, after a talk with the local sheriff - was able to take off with no problem.

When you can talk to random people and they or someone they know has had a problem - it is time to accept the fact and solve the problem.

If you insist on using a carb - study airplane systems that prevent ice and design yours to do the same. And then test, test and test

Remember a system to prevent ice will not take away as much power as one that gets rid of it, if you can figure out a way to properly design one
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  #19  
Old 02-04-2008, 09:59 AM
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Default Re: Safety versus performance

Well, the complaint against designing a system that ELIMINATES the need for carb heat seems to be performance, 50 RPM means slightly less take off performance.

If you insist on a carb and make add prevention of carb ice and add VG's, which decrease take off roll - then you probably have no net taker off performance degradation.

MMM, does throttle body injection get carb ice? I think not, good solution for carb ice and keeping standard airplane stuff on an airplane engine.

Step one - review accident reports.

Step two - Admit what the accident reports tell you.

Step three - Solve problems at the root of the problem.

In this case - it is not training, it is systems.

Now, as we all know or should know most accidents are caused by knowingly flying into bad weather from good weather - spend your time making good weather decisions.
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  #20  
Old 02-04-2008, 10:42 AM
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Default Re: Safety versus performance

Quote:
a person motivated by irrational enthusiasm (as for a cause); "A fanatic is one who can't change his mind and won't change the subject"--Winston Churchill
Well, to be honest with all - i'm done with this subject. The protectors of the carb are doing so with fanatic devotion to this arcane and dangerous method of fueling a plane engine.

MMM - a review of the above quote - some would say I'm a fanatic - I don't fit as the stats show that my concern is not irrational.

There are FIVE solutions, some simple, some knot

constant flow airplane fuel injection with fuel return - simple
constant flow airplane fuel injection without fuel return - simple
airplane throttle body fuel injection - simple
electronic fuel injection, experimental from auto applications - complex
air from a warm section of the cowling or somehow automatically mixed - complex

pick one - train for real emergencies not one that you induce by making a bad equipment decision - these are your planes
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  #21  
Old 02-04-2008, 01:03 PM
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Default Re: Safety versus performance

Dust, you remind me of those congressmen standing at the potium giving a heartfelt speech with conviction on TV. When the camera goes wide you can see there's nobody in the room. That doesn't stop him a bit.

Your enthusiasm is great. Your prose is to be desired, "if you can get .... - you will". I think the proper context is "if it can.... - it will, somewhere eventually". That reminds me of a comedian named James Gregory. His quote, " you know because somebody somewhere...".
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  #22  
Old 02-21-2008, 05:41 PM
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Default Re: Safety versus performance

It was a good soap-box performance, 4 consecutive posts from the same person! I usually resolve my "I-shoulda-said" situations with the edit button
Quote:
Well, if the air filter is bypassed with carb heat on that is just poor design,
I think you are forgetting the carby heat does TWO things, it supplies heated air to melt/prevent the ice and provides air from an alternate source. If your air cleaner is blocked/partially blocked from a build-up of dust(nothing personal)/insects/taper-fit bird corpse the symptoms will resemble carb-ice and SELECTING THE CARBIE-HEAT WILL FIX THE PROBLEM.

If I had an injected engine, I would still expect (and include) an alternate air system for this reason, it just would not have to be heated just bypass the air filter - GOOD design.
Quote:
a time in florida when he gets ice, even with the carb heat turn on,
I learnt to fly in a Piper, but have only encountered icing in the air once. The engine slowly began to sound like crap, and the revs slowly fell off. It took me a while to notice because I thought it was just part of my usual battle to trim out the cruise. When I selected the carbie-heat the engine immediately sounded and performed worse! It is common dog to reverse an action that seems to make things worse, but I had been briefed on the effect so didn't. After a bit more gargling the engine cleared.

I wonder what your mate in Florida did? I wonder what I might have done some time in the future if I had encountered this for the first time and that briefing had been completely forgotten???
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  #23  
Old 02-22-2008, 10:02 AM
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Default Re: Safety versus performance

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Originally Posted by Spodman View Post
have only encountered icing in the air once. The engine slowly began to sound like crap, and the revs slowly fell off. It took me a while to notice because I thought it was just part of my usual battle to trim out the cruise.
well, it took you a while to notice, mmmmm, if you were in the pattern that "while" would have caused an off airport incident, simple as that.

Yes i am on multiple soap boxes, have been for a long time.

Ask any one about small planes and are dangerous, and guess what - they are!

But some of the danger is because we accept poor and dangerous designs and will spend money on performance and not safety.

If we want GA and experimental aviation to grow instead of continually shrinking, WE need to admit the problems and solve them. Look at the success of the parachute plane - look at the saved lives that would have been lost, look at the sales, all good stuff cause ONE manufacturer decided to design in safety

WE are the Manufacturers, we can choose to design in safe, once WE accept that certain things are inherently dangerous.
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  #24  
Old 02-22-2008, 06:07 PM
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Default Re: Safety versus performance

Quote:
well, it took you a while to notice, mmmmm,
mmmmmmmmmmm, See I have more mmmmmm's than you so I must be right... The point is it hit me at a point of maximum distraction. I identified and remedied it regardless. It is just not the problem you are making out it is. Maybe you need to examine the safety assumptions you have made in selecting a single engined aircraft, the following sounds to have more of the safety bases covered:

No matter how well an engine is designed it has the potential to malfunction at some point during its lifetime. The possibility also exists that something outside the pilot's control, like bird ingestion, could cause an engine or lift fan to fail. Therefore, any aircraft using higher disc loading will need a back-up system or systems to ensure passenger survival in case of a critical component failure.

-- In the unlikely event of an engine failure sufficient power remains to ensure a safe and comfortable landing. Since the M400 has eight engines, one or more can fail and the Skycar will still operate safely. Unlike any light helicopter or airplane, the M400 Skycar has four engine nacelles; each with two Rotapower engines. These computer-controlled engines operate independently and allow for a vertical controlled landing should one engine fail.

-- The Skycar has redundant, independent computer systems for flight management, stability and control. Should a computer problem occur backup systems would take over seamlessly. M400 has multiple independent computers for flight management and the design prevents a single-point failure from adversely effecting the performance of the aircraft. Top

-- Multiple systems check fuel for quality and quantity and provide appropriat warnings.

-- In the unlikely event that insufficient power is available to hover, the Skycar's aerodynamic stability and good glide slope allows the pilot to maneuver to a safe area before using the airframe parachutes.

-- Since computers control the Skycar flight during hover and transition, the only pilot input is speed and direction. Undesirable movement of the Skycar due to wind gusts is automatically prevented.


-- Rotary engines have very few moving parts and therefore require very little maintenance and have little opportunity for breakdown and wear.

-- Each nacelle fully encloses the engines and fans, greatly reducing the possibility of injury to individuals near the aircraft. The volantor's VTOL lift is obtained via airflow through the four ducted fan propulsion nacelles which is redirected downward by deflection vanes during vertical takeoff.

-- Even in the instance of complete power loss you and your passengers are protected. The two airframe parachutes, front and rear, will guide the volantor safely and comfortably to the ground without incidence and can be deployed in the event of a critical failure of the aircraft. With the parachutes, the pilot, passengers and the Skycar can be recovered safely. Parachutes developed for the ultra-light aircraft industry, that are ballistically ejected, have demonstrated reliable vehicle recovery above 150 feet. Recovery is possible at a much lower altitude if the aircraft has a modest forward velocity or if a spreader gun is used to spread the parachute canopy. The best primary system should use the minimum number of engines necessary together with sufficient power to hover after the failure of one engine. A multi-engine system also interfaces well with a back-up parachute system since the time between consecutive engine failures should allow sufficient opportunity for the parachute to be deployed. A single engine failure in a VTOL aircraft with eight independent ducts and one engine per duct would require 54% reserve power in order to continue to hover. The same number of engines arranged in four nacelles with two engines per nacelle requires 36% reserve power to accommodate an engine failure. The safe operation of a VTOL aircraft requires that during hover it operate as close to the ground as possible (<25 ft.) and that transition to forward flight occur as quickly as possible. With the loss of an engine at 25-ft altitude the vehicle could be landed very quickly without incident. Above 25 ft altitude one can assume that the vehicle is moving forward and generating some aerodynamic lift so that a second engine failure should not be as critical. In the case where a critical number of engines fail and transition is not complete, aerodynamic lift can extend the flight time in the critical period before the parachute is fully deployed. Thus, deployment could occur at relatively low altitudes (<25 ft.) particularly if a spreader gun is used. In any case, a new concept aircraft can be expected to undergo the unexpected. Thus, overlapping systems to ensure passenger safety would be appropriate and should be mandatory.

This farcical grab-bag of concepts is probably the main reason this alleged vehicle is 30 years in the making - AND HASN'T FLOWN YET!!! Just get up and fly mate
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  #25  
Old 02-22-2008, 06:15 PM
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Default Re: Safety versus performance

interesting spoddy, you have a problem, take while to notice it, if that while would have been under slightly different circumstances - down you go.

You then justify it by saying effectively "planes are dangerous" just accept that fact.

If this attitude did not crunch planes and kill people, it would be humorous.

BTW, it is the attitude of most aviators, you are in the majority.
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  #26  
Old 03-02-2008, 02:51 PM
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Default Re: Safety versus performance

There's one big problem with Dust's 'fly with carb heat on all the time' suggestion that I'm surprised nobody has mentioned, namely that in some conditions, it can actually CAUSE carburetor icing. If the carburator air temperature is outside the range of carb icing, having carb heat can actually raise it into that range. It's a combination of humidity and temperatures, not just temperature, and the suggestion given would leave a pilot with no method for dealing with the loss of engine power.
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  #27  
Old 03-03-2008, 10:29 AM
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Default Re: Safety versus performance

Chairboy, you just might be right, so you too feel there is no way to make a carb safe! I agree

I don't think you are right cause there are planes with carbs that do not have carb heat, just alternative air, but you may be right! Also colder air has less humidity in it, if you take 40 degree air with 90 % humidity in it and heat it up to 70 degree air, it is quit a bit drier, relatively speaking.

Why not get an independent view, talk to your spouse and explain that you can fuel inject, either throttle body or runner, or put a carb in and if you put a carb in you promise to practice, practice hearing the itsy bitsy change that the engine makes when ice starts (while you are talking to her/him or the tower or changing the radio freq or whatever ) and will turn carb heat on in time to stop from losing your engine.

Then go to the ntsb accident site and do a search for icing accidents, no need to define the search further than that, you won't get any plane icing accidents to pop up, and have her or him read them for a while.

The quantity of accidents that pop up from just the last 12 months will keep you reading for a long, long time.
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  #28  
Old 03-07-2008, 12:44 AM
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Default Re: Safety versus performance

I'm putting an injected 13B in mine, no worries here. It was the 'fly w/ carb heat on all the time' advice that had me worried.
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  #29  
Old 04-07-2008, 09:52 AM
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Default Re: Safety versus performance

Well, at the airport workin on my intake manifold Saturday - Max and I stopped at the terminal building for a pit stop and coffee. Stated chatting with a guy and i made a comment on carb icing and its dangers.

He pondered a moment and said he had been flying a 182 this past winter and it was so prone to carb icing he just left the carb heat on all the time.

i really chuckled to myself.

He was waiting for a student pilot to give flight instruction to.
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