Not to be picky, but there are no military airplanes equipped with all aircraft chutes, so that doesn't seem applicable even discounting the military thing.

Uh, one pound thrust is not equal to one HP. The seeming similarity of the two values has tricked you.

Conversion between the two is complicated, but a general rule of thumb is about 2.5 pounds thrust is 1 HP.

No go back and convert those SFC numbers again. You'll be shocked!

Note that SFC gets a LOT worse at low altitude and part throttle. You only reach the published number at max temp.

Mike C.

Not true at all.

I just need the underlying mechanism explained for the following:

1. Why do Corvalis pilots get into one third the fatal situations as Cirrus pilots?

2. Why are there no passenger initiated chute pulls in a Cirrus?

3. Why is there no chute pull for 2/3rds of Cirrus fatal situations?

By stating I am intransigent in my opinion, you are trying to excuse your lack of substantive answers to the above questions. It is a fallacious ad hominem argument.

Mike C.

Done on purpose so that added power didn't cause a pitch up. Indeed, almost all business jets has a bit of engine pitch down for this reason (or high thrust line like the CE750) and they have a bit of engine cant outwards (adds yaw input to reduce OEI rudder forces).

The SF50 angle is exceedingly larger than you need so it GREATLY overdoes the pitch thing. It is also above the airplane drag line, adding to the effect.


It is around 28% of MAC. That's just they way wings work.


Uh, you posted a picture of it with handy reference lines drawn.


V tails are as much surface area if not more than traditional tails. Look at the size of them compared to, say, and EA500.


I'd be curious to see that demonstrated with planes of otherwise identical power and weight. I suspect the difference is negligible or attributable to other differences.

Are you accusing Beech of using a less efficient tail on the 36? Why would they do that on their top of the line piston single?


Go for it.

Mike C.

And we have a winner. Anyone willing to strap themselves into anything less than maybe a B737 is probably not the brightest individual when it comes to risk management.

Cirrus has remove the video:

http://www.cirrusworld.com/cirrusaircra ... 1c623.html

In it, Klapmeier talks about taking his two young sons on a night time trip, in icing conditions, to Jackson Hole airport, and having to rush there before the storm closes the airport so they can go skiing. The plane he took at the time was operating under an experimental certificate.

It sent chills down my spine. Mountains, icing, weather, schedule, night, experimental, with kids, piston, single. Would any of YOU do this?

The real issue here is not that he did this, but that he produced a VIDEO TO BRAG ABOUT IT to sell airplanes!

Mike C.

One semi-practical ? re the SF50 and the chute:

If the engine fails at altitude, and you pull the chute what effect does that have on cabin pressure? I assume the engine the source of bleed air for pressure in the cabin. I also assume that the cabin leaks air a bit (and maybe even a bit more when the chute changes the loading of the structure). Does each seat have a quick don O2 mask? How long does it take, while under the chute, to get from 25K down to breathable air? Is the ops plan "with an engine failure at altitude, drop gear, drop flaps, emergency descent and when <12K pull the chute"?

W/o an understanding/plan for those issues, isn't the chute something of a non-sequitur?

RAS

Gotta say I have seen this video an it was AWFUL. Really honest to god truly horrible. It was like some video that was made by the FAA to point out every piloting judgement mistake you could make.

This all reflects on the character of the person speaking it and not the plane's capabilities. But the video was jaw droppingly bad.

Mike - I only know of one chute failure from out of envelope in a plane what was near/over VNE. Lots of deployments from near typical cruise speeds. Are there other accidents where the chute failed due to airspeed/envelope issues. I know there was one in TX that was just a dud.

Bingo.


Exactly. They took a single on trips that fit the risk profile for a twin. The "spent" the risk credit they perceived the chute gave them on taking riskier flights.


No, that works only if the chute provides the same benefits as a second engine and clearly it doesn't.


From the NTSB report:

"The pilot told the right seat passenger to pull the emergency parachute handle"

Doesn't count as a passenger initiated chute pull.


I think it is honest to admit this is not a rational decision. That's okay and it most likely makes you that much safer knowing that.


That's a little unscientific. Why do so many macho pilots chose a Cirrus to do it in?

Also, many of these accidents are solo. Macho stupidity is usually an audience induced phenomenon.

Mike C.

Great point! Any ideas?

And we have a winner. Anyone willing to strap themselves into anything less than maybe a B737 is probably not the brightest individual when it comes to risk management.

A little, sure. It's not any worse than a PC12 or a King air with the PT6 intake cone below the compressor.

I think the PT-6 air needs to reverse direction? The cirrus looks more like a 727 top engine straight into compressor but through a curved duct.

Which, to be fair, is a very inefficient engine.

No delicate way to say this, but yes, you have.

Jet engines are in thrust specific fuel consumption, TSFC, which is pounds of fuel per hour per POUND OF THRUST. Roughly, every 2.5 pounds of thrust is one HP. Exact equivalence is complicated.

Shaft engines are in brake specific fuel consumption, BSFC, which is pounds of fuel per hour per shaft HORSEPOWER.

Turboprops can also be express in EFSC, effective specific fuel consumption which includes the benefit of the jet exhaust as if it were delivered to the prop.

A Williams TSFC of 0.48 lbs/lbf/hr is an equivalent of about 1.2 BSFC. That is, it would take a 720 HP shaft engine to equal the 1800 pound thrust of the FJ33 on the SF50.

A PT6 is about 0.6 lbs/hp/hr BSFC, and about 0.57 lbs/hp/hr EFSC.

My TPE331-10AVs have been measured at 0.49 lbs/hp/hr BSFC and 0.44 lbs/hp/hr EFSC.

A standard light aircraft piston engine takes off about about 0.6 to 0.7 lbs/hp/hr BSFC. It cruises ROP around 0.45 lbs/hp/hr, and LOP can get down to maybe 0.38 lbs/hp/hr.

The SF50 has a 1800 pound rated FJ33. It burns 864 pounds of fuel per hour (~130 GPH!) when making that 1800 pounds thrust.

A 720 HP shaft engine (my TPE331s are 715 ESHP so a near perfect fit) would deliver the same rough performance as the jet. A TPE331 would burn 47 GPH to do that.

A 720 HP piston engine would burn abut 45 GPH LOP (fuel is lighter, so more gallons to get the pounds).

Of course, things are not directly comparable like that as each engine has its own installation requirements and systems support, but the basic point is there.

This should give you a feel for just how inefficient the jet is compared to the other engines. Jets are only efficient IF you can fly high in thin air.

Mike C.