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-   -   Why does the Falcons have 3 engines? (https://www.pprune.org/tech-log/108392-why-does-falcons-have-3-engines.html)

E1453 10th Nov 2003 09:36

Why does the Falcons have 3 engines?
 
With the exception of the Falcon 2000, all new Falcons (as long as I know) have 3 engines. Why?

Is it for the passengers / owners feel safer?

It doesn't make sense, at least in the costs aspect.

pigboat 10th Nov 2003 11:40

I've had a P&W rep tell me it's so's you can finish a flight on two, but I suspect he was biased.;)

skyhawk1 10th Nov 2003 12:34

It's so that they can do long range flights without having to worry about ETOPS certification

Torquelink 10th Nov 2003 18:41

I had a Challenger rep tell me it's because Dassault fit "Garrett Grenades" but I think he was being a little unfair!

747FOCAL 10th Nov 2003 20:45

It gives the fat cat that owns it a little piece of mind when out over the pond. And.....mostly because if you can afford a new Falcon, engine maintenance is not one of your worries. :E

Zoom 10th Nov 2003 21:28

And why does (did?) the Lockheed Jetstar have 4?

GlueBall 10th Nov 2003 22:15

And the B-52: Eight (8)!

Onan the Clumsy 10th Nov 2003 22:35

...and the Dornier Do X had TEN!

Zoom 11th Nov 2003 03:20

I suppose that's why those last 2, and others like them, had all those engineers on board - just to work the throttles!

pigboat 11th Nov 2003 05:26

Gentlemen, please. Enough with the terrible jokes already. Time for a serious answer. :D :p

The Jetstar prototype was originally built for a military application with two 4800 lb thrust Bristol Orpheus engines - that were to be built under license by Curtiss-Wright - and no slipper tanks. The deal to build the Orpheus in the US fell through, and the American military were reluctant to acquire an aircraft with a foreign built engine. Lockheed went back to drawing board and added two pairs of 3000 lb thrust P&W JT12's in place of the single powerplant, added two 560 gallon slipper tanks to counter the increased fuel requirement and as they say in French "Viola!"

Trivia tidbit: The four rear mounted engines configuration Lockheed used was first proposed by Vickers in 1956, for the project that became the VC10.:cool:

Specnut727 11th Nov 2003 18:35

What's wrong with terrible jokes ?

I thought I saw a VC10 once, but it was only an Ilyushin !!!!

Boss Raptor 11th Nov 2003 20:51

Educated guess - at the time of the inception of the first of the Falcon trijets, the Falcon 50, the only proven light fan engine was the TFE 731 series which had a track record on the LR35/36 and 125-700 (the later 731-5 series was fitted to the Falcon 900 and 125-800).

The only other suitable contender in the power bracket for a 2 engined alternative being the ALF502 from Avco Lycoming which at the time has all sorts of teething problems which were being experienced by operators of the 146 and Challenger 600.

Dufwer 11th Nov 2003 21:18

Specnut727, that has to be the worst aviation joke I have ever read.

Made me smile :D

D

DA50driver 12th Nov 2003 08:03

3 Engines on Falcons
 
I don't know, but it feels really good to have 3 throttles in my hand. I have flown a Falcon 50 for a couple of years, and it is a wonderful airplane.

Also, if you lose one engine on a twin, you loose a lot of your excess power(which makes you climb). If you lose one of three, you lose a lot less of your excess power on a percentage basis.

The airplane has an amazing performance envelope. We operate out of a 4300 foot strip, and can legally carry 3.5 hours of fuel on a wet runway, ISA day. Off longer runways we can non-stop it to Western Europe.

DanAir1-11 12th Nov 2003 11:29

specnut727!! LOL - :D

VC10 was a thing of beauty! Sad to see her retire from airline ops as indeed I was with Tridents and my beloved 1-11's!

The Ripper 12th Nov 2003 12:51

So then the answer must be it has three engines because it has three throttles.:cool:

Mad (Flt) Scientist 13th Nov 2003 01:48


DA50driver
Also, if you lose one engine on a twin, you loose a lot of your excess power(which makes you climb). If you lose one of three, you lose a lot less of your excess power on a percentage basis.
But since both the twin and the trijet must meet cert requirements, the worst you can ever be for FAR25 is:

takeoff first segment (gear down):
on a twin:
"positive" climb (25.121(a))
On a trijet:
0.3% climb (25.121 (a))
takeoff second segment (gear up):
on a twin:
2.4% climb (25.121 (b))
On a trijet:
2.7% climb (25.121 (b))
above 400ft:
on a twin:
1.2% climb (25.111(c)(3)(i))
On a trijet:
1.5% climb (25.111(c)(3)(ii))

So following engine failure the climb gradients are not dissimilar - which means that all other things being equal a twin will have better performance (in terms of excess thrust) when all engines are operating, which is the most common case (you hope :)). So unless that 0.3% difference is make-or-break - in which case the twin won't be taking off without unloading - the twin is usually a better climber.

Dale Harris 16th Nov 2003 17:07

There is a bit more than just the certification to it mad scientist. What you quote is the certification requirements. I can't think of any of the aircraft quoted above that wouldn't exceed those requirements, some by a large margin. So the difference lies in the figures actually achieved by the individual aircraft.

Intruder 17th Nov 2003 03:40

Ripper:

No, the real answer is that it doesn't fly very well on 2 engines.

pigboat 17th Nov 2003 07:16

...and the thrust reverser on the center engine is to make noise so you think it's slowing you down. ;)


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