TopHatter

Regardless of the expense, how much safer is a twin-engine aircraft when you look at the various single-engine aircraft losses due to engine failure?

Maxor

ARe we counting enough extra thrust to make up the weight of the extra engine and control systems or are we just going for a basically comprable misison wise twin engine light fighter? I'd say on average you are looking at about 40% more over the life of the aircraft. thats a very dirty and rough estimate.

wabpilot

That depends on what singles you count. For civilians, single engine aircraft are much safer because they are much easier to control after an engine failure. Among business operators, twins and tri-jets are much safer. That is due to two factors, more hours and more simulator training. Among airlines, it's a mixed bag. For Part 121 airlines, there is no question that twins, tri-jets and quads are safer. But, if you count in Part 135, it gets messier. Singles have a good safety reputation in Part 135, because of the large number of piston twins operated there. If I had to pick between a TBM700 and a Beech Baron both operating under Part 135 rules, I would probably side with the TBM700.

In the military, there is no doubt that the F-18 has been exceptionally safe. But, there are twin jets that have not been so. Singles like the F-16 and A-4 have had a rough history. Among the A-4 community it was not unrealistic to expect a fifty percent attrition over twenty years of service. The F-4 community saw some high attrition numbers. A lot of that is attributable to aerodynamics. The F-18 flies better with one engine failed than the F-4 does.

Sorry, no clear cut answer.

Maxor

Wab Not being an aerospace engineer I can't say for certain but judging from looks don't most things "fly" better than the F-4 did/does? It looks like it has very little when it comes to glide ratio and controlability without power.

Bluesman

wabpilot's correct on both things: when I got my multi-engine ticket, just about 90% of the training was engine-out procedures. This is just common sense, because obviously, when your airplane has suddenly become 'asymmetrical' - one side thrusting, the other side dragging - you are going to have some SERIOUS controllability issues, quite apart from a massive loss of power.

Also, I back him up that a single motor on a 'good' design beats two on a 'bad' design.

But, all other factors being equal, and they never are , I'd rather have two engines than one.

__________________
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- George Orwell

Bluesman

My next-door neighbor back in Tampa was a retired AF Lt Col fighter driver, and he did some flight-test on F-4Ds. He liked 'em, but said it WAS a challenge to fly it well, at least compared to his time in F-15s. (And note that he flew 'em in combat in Vietnam, AND flew F-104s, without a doubt the most challenging aircraft ever in widespread use in the inventory.)

He said it was never happy at low altitudes, and wanted to 'buck you off', while the F-15 was just so easy in almost any flight regime.

When he transitioned from Phantoms to Eagles, the thing he noticed immediately was the different response at low speeds and a high power setting: the F-4 would fly away from it as you'd expect: with the knots coming up, it would get easier and easier to fly, until it was back in the 'sweet spot' that it liked best, between 300 and 600 knots, and if there was little or no g on the airplane, GREAT, it liked it even better and took less time to get to the 'right' speed.

The F-15, on the other hand, would just pin your ears back when you slammed the throttles in, and unless you were REALLY slow, it didn't mind if you were in a high-g maneuver or not, you'd be getting your airspeed back without having to 'manage' the increasing speed.

Bottom line: if you were good in an F-4, you were the 'real deal', a fine fighter pilot.

Maxor

As a aircraft avionics systems (most electronics and navigations systems for those uncertain. Also includes RWR and any other EWS on the airplane) guy. I've done a number of phased repair cycles for both duel and single engined planes. That 40% more expensive number was base on based on about 22% more expensive on start-up purchase and 15% increased maintence hours on the dual engined aircraft and 3% Based on operating costs (two smaller engines in a heavier airplane still use more fuel it seems.) Used the numbers from export versions of the f-16 and the f-18 (original hornet) (the f-18L would have been better but numbers on it are scarce to find quickly on the internet). Does anyone have disagrements with this or would you care to look at two other similair aircraft from a different manufacturer to determine wether this holds true across the board or if its just this case?

wabpilot

In slow flight, the F-4 is a challenge. Its stall characteristics are brutal and it will flat spin with minimal provocation. An engine out, is more than enough to provoke a flat spin. Thus, speed management is vital. That being said, I liked flying the F-4. It's slow speed control was better than the F-14. No PIO at all. I never was concerned about a ramp strike in the F-4, that was a constant concern in the F-14. At altitude, the F-4 had the power to explore parts of the envelope where test pilots should go on their own. The F-14 does not. Fortunately the overtemp sensor on the F-4's armored windscreen usually kept people out of trouble. (Certain maintenance test pilots, notwithstanding.)

I would call the F-14 more refined than the F-4. The F-18 is just in another league. It's got to be the best flying fighter ever. It is more than a refinement on the F-14. It was coming into the fleet as I was leaving. I never qualed, but I did make it to F-18 maintenance school. It's no wonder the thing is so great. It is built by people who want you to fix it and make it fly again real quick.