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lindyman
08-16-2004, 08:12 AM
Just curious, is there any aircraft flyable in AEP that you can stall when taking -G? I haven't had the possibility to try them all out, because of the sheer numbers, but all I've tried simply become unable to keep the nose up when slowing down inverted. I haven't tried accelerated stalls, just -1G.
_
/Bjorn.

lindyman
08-16-2004, 08:12 AM
Just curious, is there any aircraft flyable in AEP that you can stall when taking -G? I haven't had the possibility to try them all out, because of the sheer numbers, but all I've tried simply become unable to keep the nose up when slowing down inverted. I haven't tried accelerated stalls, just -1G.
_
/Bjorn.

PBNA-Boosher
08-16-2004, 12:11 PM
With Neg. G's carborated aircraft will stall. Not in an aeronautical sense, but in terms of the engine. These planes as are currently in AEP are:

J8A (Gloster Gladiator)
Cr.42
G.50
Hawker Hurricane Mk.I
I-16
I-153
P.11c

I think that's all of them. Basically Negative G's will cause the engine to cut out. If you hold it for too long the engine will stop because it has been starved of fuel. you can restart in the air normally if you are above a a certain speed. I think for the I-16 you need to be above 250 kph for it to work. Otherwise you're dead meat on a very tall stick.

Even though these planes are carborated, it doesn't mean they're not dangerous! Next time you make fun of the I-16 or I-153, they'll come and bite you in the @$$, be sure of it!

Boosher
_____________________________
"So do all who live to see such times, but that is not for them to decide. All you have to decide is what to do with the time that is given to you..."
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Cragger
08-16-2004, 12:39 PM
All aircraft are carborated in this time frame, its just the ones that don't have fuel injection (known today as throttle body) and rely on gravity feed fuel bowls in the carborator that can stall the engine.

There are two main types of fuel injection. Forced injection into a carborater or intake manifold and direct port injection where each cylinder has one or more fuel injectors.

http://redspar.com/redrogue/cragger_sig.jpg

lindyman
08-16-2004, 03:15 PM
Ah, I should've thought about the good chance for misunderstanding, since the same word is used for two completely different things, both of which apply very well to what I wrote.

I don't care much about the engine in this case, I mean aerodynamically, where the wing becomes unable to increase lift with increased negative AoA.
_
/Bjorn.

PBNA-Boosher
08-16-2004, 04:58 PM
Oh I see! Nope, there is no way to stall the plane while pushing down on the stick, as you are letting gravity do the work when you push down on the stick. However, depending on your speed, you will get one hell of a redout!

Boosher
_____________________________
"So do all who live to see such times, but that is not for them to decide. All you have to decide is what to do with the time that is given to you..."
-Gandalf

Jason Bourne
08-16-2004, 09:27 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Cragger:
All aircraft are carborated in this time frame, its just the ones that don't have fuel injection (known today as throttle body) and rely on gravity feed fuel bowls in the carborator that can stall the engine.

There are two main types of fuel injection. Forced injection into a carborater or intake manifold and direct port injection where each cylinder has one or more fuel injectors.

http://redspar.com/redrogue/cragger_sig.jpg <HR></BLOCKQUOTE>

do a little more research, this is what i found about FI, though i dont know how well it relates to WWII planes:

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>A fuel system using a pump and injectors instead of a carburetor to meter fuel. Fundamentally, there are four types, though there are many variations of these types. Direct injection squirts fuel right into the combustion chambers, and is used primarily in commercial diesel engines. Pre-chamber injection, used on nearly all passenger-car diesel engines, injects fuel into a small chamber above the main combustion chamber. Port injection, sometimes called multi-point injection, is widely used in gasoline engines and puts the fuel charge into the individual intake passages but somewhere upstream of (though close to) the intake valve. Throttle-body injection, also known as single- or dual-point injection, employs one or two injectors squirting into a carburetor-like device in gasoline engines called the throttle body. Fuel can be delivered mechanically or electronically and can be timed, continuous or a combination of the two. In mechanical injection, a reciprocating pump feeds the injectors. Electronic port fuel injection employs a constant-flow pump and electromagnetic injectors to open and close each injector. Electronic injection is most frequently a timed system, in which the length of time the fuel is squirted in is precisely controlled (according to variables such as engine speed, manifold vacuum and coolant temperature). Continuous injection delivers fuel in a steady flow. Sequential fuel injection is port injection timed to the opening of each injector's associated intake valve so that fuel is delivered to each cylinder in its proper firing sequence, not to part or all of the cylinders at once.
<HR></BLOCKQUOTE>

and not all planes in WWII were carborated (sp), infact the Me 109s best manuver in the early war years was a -G loop, since the hurris and spits would have thier engines cut out if they tried to follow.

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>The Me-109 was a formidable opponent for the early marks of Spitfire; its low speed handling qualities were excellent and its rate of climb matched the Spitfire. Moreover, it had a higher service ceiling and it had one other major advantage - fuel injection. This allowed the Me-109's powerplant to run flawlessly regardless of the aircraft's attitude, unlike the Rolls-Royce engines of early Spitfires, which cut out at the slightest suggestion of negative G<HR></BLOCKQUOTE>

QED: the 109 did not have a carburated engine, but a MFI engine.

oh, and a throttle body != (is not equal to) a FI system.

sorry, but im allergic to unchallenged BS

TX-EcoDragon
08-16-2004, 09:28 PM
There is no -1G stall, though I don't see a +1 G stall either. As far as accellerated stalls, yeah, they can happen + or - . Try a snap roll, and then try it outside.

Some planes dont have much negative elevator, like the lagg 3, spits, and im sure many others, will not.

But in short yeah, accellerated stalls are possible in many aircraft.


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Hiriyu
08-16-2004, 09:44 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Cragger:
All aircraft are carborated in this time frame, its just the ones that don't have fuel injection (known today as throttle body) and rely on gravity feed fuel bowls in the carborator that can stall the engine.

There are two main types of fuel injection. Forced injection into a carborater or intake manifold and direct port injection where each cylinder has one or more fuel injectors.

http://redspar.com/redrogue/cragger_sig.jpg <HR></BLOCKQUOTE>

I agree with Jason above.

There is no such thing as forced [fuel] injection into a "carborater"; the closest thing to this concept would be a blow-through supercharger or turbo setup, and relates specifically only to increasing airflow (enrichment is done via carb work and/or other controls).

Also, there is no float bowl present in any F.I. system that I'm aware of http://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif.

BTW guys, it's "carburetor" - Old man Weber is spinning in his grave http://ubbxforums.ubi.com/images/smiley/cry.gif.

WTE_Galway
08-16-2004, 09:54 PM
he is talking about stalling not engine cut out

but while on the topic .. merlins FLOODED under negative G from excess fuel - they did not suffer fuel starvation

Cragger
08-17-2004, 12:23 AM
If you break it down to its fundamentals Throttle Body(CPI), TPI, MPFI and a carb are all the same thing. Mixing fuel and air before before they enter the combustion chamber. They are three approaches to the same concept. Three used forced injection (artifical pressure provided by a pump) to insure continous proper fuel flow. One uses a float/fuel bowl and jets that uses gravity to supply the proper fuel flow. A Throttle body being nothing more than a carb minus the complexities of float bowls, metering valves, air and fuel jets, and accelerator pump replaced by a fuel injector. The remaining fuction of a carb and throttle body is the same, to atomize and supply a fuel/air mixture to the intake manifold.

Direct injection which I errorunously called TPI is a different concept, injecting fuel into the combustion chamber after the air has been supplied and begun compression.

It all depends on where you consider the major difference being the mixing before or after the air mass enters the cylinder or simply on the system used to deliver the fuel to the point of mixture.

The -G engine stall aircraft suffered was purely dependent on the use of a gravity regulated system and was fixed by using a artifically pressurized injection system regardless of it being Direct, TPI or Throttle Body.

This is a fine example of oversimplying something in relation to the subject at hand and posting in a rush after having not slept in 35 hours. What I was attemting to say was that no aircraft of the WW2 era to my knowledge used Direct combustion chamber injection all used pre cylinder mixing of some typed. Fuel Injection is also one of those lovely technologies that is greatly overcomplicated by the industry itself. As there is many forms CPI, TPI, MPFI, EPI, TBI, EFI, MFI, MPI, SFI. Many of these are simply different acronymes for the same thing. Here is a article on the complicated injection system terminology and what they really are. You can see why I was attempting to simplify my previous post and perhaps went way too far. However I had minutes at the time instead of the half hour its taken to put this post together.

http://www.chevyhiperformance.com/techarticles/49279/

BTW here is a good link on a MPFI system if you want a visual rendering. MPFI is just TPI with more injectors located to directly spray fuel into a open port/valve. MPFI is also known as SFI which is named different from MPFI because it is combined with EFI and a ECU instead of mechanical/electrical control. Confused yet?

http://www.indiacar.com/index2.asp?pagename=http://www.indiacar.com/infobank/mpfi.htm

http://redspar.com/redrogue/cragger_sig.jpg