To me the only way to compare a/c performance is TAS but of course in the same atmospheric conditions (ISA).
Why would IAS be better?
It's actually GS that really counts ;) Peter's point is that TAS varies with altitude AND temperature, so alexisvc you have remembered data based on the temperature at that point in time, which is just one data point..
well ,if it's the GS, then I win: 225 Kts GS yesterday, in 2500 feet with 55 percent power and 10 GPH :-)
But it was so turbulent that it made me sick (let alone scared when the plane yawed back and forth 20 degrees while rolling L/R 30 degrees ...
"Two engines only means that an engine failure is two times more likely to occur".
That's such an old and worn out comment, I think I've heard it a million times. But, is it actually true? Anybody in the statistics department?
Twins have one huge benefit over singles in that second engine. It actually provides you with an OPTION! You can land, like any single, or keep on flying. For some reason though, twins are presumed always to keep on flying, and I think that's where flight training could do a better job.
One problem could be that twin training is mainly aimed at getting the rating in order to move into an airline job, so there's not so much effort going into suitable real world light twin operational procedures. For example, one should calculate ASDA and balanced field lengths and stuff, but that really has more merit in a twin turbine.
When checking out on the Tecnam P2006T I found that it was a very nice alternative to an Arrow or similar aircraft, and handled much like a single. Performance isn't ever going to be stellar, but if you apply a combination of single engine emergency procedures with twin engine options you really should end up with a safer package overall.
The parachute gives you one option and that is to float with the wind, completely out of control...
I know that. The question is: What is MORE DANGEROUS? Engine failure in a single or in a twin. And I am quite sure that for all amateur pilots the answer is: Twin.
Lufthansa, for example, does not train in piston twins anymore. You fly a Bonanza and then a twin jet next.
if it's the GS, then I win: 225 Kts GS yesterday
Come on guys, stop pulling my leg 
GS counts only if you sit on the ground and wait for a tailwind, and then you fly downwind, don't care where to, taking pics of your GPS GS readout to post on a forum.
IAS (and fuel flow, at whatever engine operating point you feel shows your plane in the best light) is the most basic measure of airframe efficiency.
TAS is also OK but you have to supply the OAT and altitude, without which TAS is meaningless. If you do supply them, TAS is as good as IAS. But no better. And it means anybody doing comparisons is going to have to get out a TAS-IAS converter to always work it back to a surface IAS, or a TAS at some consistent condition... That's why salesmen love TAS.
That's such an old and worn out comment, I think I've heard it a million times. But, is it actually true? Anybody in the statistics department?
Taking it in its totally narrow sense, it must be true. The Saturn 5 with 5 engines had 5x the prob of an engine failure than if it has one big engine.
I have heard old twin guys say that the chance is actually more than 2x, due to the much longer control cable runs, and control cables do account for a good % of loss of engine power / prop control incidents (neglected cables jam, or break off). And the longer fuel runs (blockage, more exposed to cold airflow (an Aztec owner, who almost never posts here but has a huge forum profile, says he has a 100% chance of an engine failure due to icing below -15C, so uses EDME/PRIST), etc. Also, some believe, more damage-causing vibration because the engine frame is just screwed to the wing spar, rather than being screwed to the very rigid firewall in a SE.
Then you have great stuff like the turbocharger exhaust burning through the wing spar if the pipe comes apart.
So, while this must be very much system dependent, I think 2x the chance of having a heart stopping moment is about right
I think one needs to be very separate about the pilot factors e.g. needing more currency when close to the ground, more chance of fuel mismanagement (due to more complex fuel systems, and due to more chance of repeated flights with the fuel level never high enough to be visually verifiable because some types have a poor full-tank payload - google G-OMAR AAIB for an absolute classic whose operator had (has) a charter AOC).
And - hey I am never controversial - a twin owned by a given person is less likely to have €X thrown at it by Person Y than a SE owned by person Y, due to the greater money flow rate required by the twin for a given condition. Evidence? Your local airfield... admittedly this is assisted by most twins flying having been out of production for decades.
Obviously an engine failure in cruise should be a non-event, which is highly relevant to flights over water, mountains, etc. And I think for most twin owners that is the main driver.
The fact they are probably more likely to kill themselves when close to the ground is an individual choice - same as countless other things in flying where you assess the risk and - on a noncommercial flight - hopefully compensate for it.
Yeah, Lufthansa pilots are lucky bastards.
Yes, I agree with you that twins are probably more dangerous for inexperienced pilots, and I think it has to do with the training and mindset. In the Single, decision making is easier. You're going down, so if there's a chute, pull it and enjoy the ride. In a twin you just keep on going, even if it's impossible.
Haha, I ALMOST posted the pic with my 225 kt GS :)
I still don't see why IAS would be a better meter for aircraft performance. Airplane performance data is given at ISA conditions, so the data is already comparable.
Or, more simple: A SR22 NA is faster than a TB20 ;-)))
You must admit that 147 KTAS at 13° C in 4400 feet with 11.3 GPS is impressive, Come on, say it!
You must admit that 147 KTAS at 13° C in 4400 feet with 11.3 GPS is impressive, Come on, say it!
(cough, cough - we get the same performance in the DA42-VI!)
Yes, with two engines! Does that count? ;-) I wonder how much maintenance of the DA42 is compared to the SR22 ... really have no idea!
