EBJ1248650 From United States of America, joined Jun 2005, 1859 posts, RR: 2 Posted (4 years 7 months 1 week 6 days 14 hours ago) and read 6089 times:
Typhoon and the F-22 both have power to spare; can cruise at Mach 1+ without use of afterburner. With this kind of excess power, why don't these airplane take off in military power. I can't number the many photos I've seen of F-22s and Typhoons taking off in afterburner and it seems unnecessary. While stationed at Luke AFB, I often saw clean configured F-16s take off in military power and they had no problem at all. Is the use of afterburner for F-22 and Typhoon take offs for show or is there something I'm not understanding?
Highlander0 From United Kingdom, joined Sep 2007, 165 posts, RR: 0 Reply 1, posted (4 years 7 months 1 week 6 days 14 hours ago) and read 6089 times:
Perhaps it is to get the aircraft to the safest speed incase of a one engine failure. I think the F-16 would have a *slight* problem on that front.
I know that Tonka (Tornado) pilots regulary leave re-heat on untill bout 300 knots (555 km/h) which is best single-engine speed should a failure occur.
PADSpot From Germany, joined Jan 2005, 1676 posts, RR: 6 Reply 2, posted (4 years 7 months 1 week 6 days 14 hours ago) and read 6086 times:
Quoting EBJ1248650 (Thread starter): With this kind of excess power, why don't these airplane take off in military power. I can't number the many photos I've seen of F-22s and Typhoons taking off in afterburner and it seems unnecessary.
German Eurofighters usually take off W/O reheat. Exception are alpha-scrambles, air shows or flight under heavy loads. I can just repeat myself once again: Do not draw any conclusion from air shows or events alike.
It is for noise reduction, reduction of fuel consumption and reduction of wear. Also since the introduction of the EF German Air Force is once again conducting simultaneous take offs which had become somewhat rare after the the end of the Cold War.
Checksixx From United States of America, joined Mar 2005, 896 posts, RR: 0 Reply 3, posted (4 years 7 months 1 week 6 days 12 hours ago) and read 6076 times:
F-22's normally take-off without afterburner. Most of the pictures you see that the Raptor is taking off with afterburner are at airshows.
Garysted From United Kingdom, joined Sep 2005, 48 posts, RR: 0 Reply 4, posted (4 years 7 months 1 week 6 days 12 hours ago) and read 6071 times:
Hi,
I think you'll find it's very, very rare to see operational RAF Typhoon's depart in afterburner - unless it's a airshow performance or a back seat ride for a lucky guest. During numerous visit's to Coningsby for photography I've only seen one afterburner departure - and that was a ride as said above. I've seen operational QRA departure's with wing tanks and eight AAM's and the three tank configuration, all without burners. I guess the high percentage of Typhoon burner shot's on A.net would be because many are airshow pics or are so rare that they've been uploaded specifically because of it. I think a lot of the pre-delivery flights from Warton are also carried out in burner - I would love to photograph burner shots at Coningsby!
EBJ1248650 From United States of America, joined Jun 2005, 1859 posts, RR: 2 Reply 5, posted (4 years 7 months 1 week 5 days 16 hours ago) and read 5868 times:
I think you'll find it's very, very rare to see operational RAF Typhoon's depart in afterburner - unless it's a airshow performance or a back seat ride for a lucky guest. During numerous visit's to Coningsby for photography I've only seen one afterburner departure - and that was a ride as said above. I've seen operational QRA departure's with wing tanks and eight AAM's and the three tank configuration, all without burners. I guess the high percentage of Typhoon burner shot's on A.net would be because many are airshow pics or are so rare that they've been uploaded specifically because of it. I think a lot of the pre-delivery flights from Warton are also carried out in burner - I would love to photograph burner shots at Coningsby!
Gary
Gary, to you and the others who responded, many thanks. Now I know the score. Much appreciated. Earl
AutoThrust From Switzerland, joined Jun 2006, 1254 posts, RR: 8 Reply 6, posted (4 years 7 months 1 week 4 days 21 hours ago) and read 5759 times:
Quoting PADSpot (Reply 2): Exception are alpha-scrambles, air shows or flight under heavy loads
Isn't it quite sensless using apart QRA to use afterburners even its a flight with heavy load?
Quote:
The 17 Sqn aircraft was airborne after a 2,800ft (850m)take-off roll in full reheat, before climbing to an altitude of 40,000ft using dry power. “With six Paveway IIs and six [air-to-air] missiles, the aircraft was carrying a weapons load equivalent to three legacy platforms,” says Pemberton. “This fit clearly illustrates the impressive nature of the Typhoon’s performance and gives an exciting insight into future operations.”
PADSpot From Germany, joined Jan 2005, 1676 posts, RR: 6 Reply 7, posted (4 years 7 months 1 week 4 days 20 hours ago) and read 5746 times:
Quoting AutoThrust (Reply 6): It could have done the takeoff perfectly without afterburner, it would have just needed a little more runway. Waste of fuel don't you think?
Runway length is fixed and military airplanes need much larger security margins compared to civil airliners as braking power is relatively much lower. Typical military runways at fighter bases are 2000-2400m. With a heavy load you simply need to be airborne after about 1000m, because otherwise you don't have enough runway left to come to safe stop in case of an rejected take-off. You can almost say required runway length is take-off distance *2.
Norlander From Faroe Islands, joined Sep 2007, 128 posts, RR: 0 Reply 8, posted (4 years 7 months 1 week 4 days 20 hours ago) and read 5743 times:
Quoting PADSpot (Reply 7): ...military airplanes need much larger security margins compared to civil airliners...
Please explain that point a bit more, as I understand it military equipment doesn't need to hold to the stricter security margins of civilian use. They are not liable in the same way. To put it another way: "There is no way a plane like the SR-71 would ever be certified for civilian use".
TheSonntag From Germany, joined Jun 2005, 3311 posts, RR: 33 Reply 9, posted (4 years 7 months 1 week 4 days 19 hours ago) and read 5733 times:
Quoting Norlander (Reply 8): Please explain that point a bit more, as I understand it military equipment doesn't need to hold to the stricter security margins of civilian use.
I am not an expert, but NATO has certain rules which are not mandatory for civilian operations. For example, as far as I know, fire brigades must be ready when a transport plane is switching on its engines, at least my grandfather told me that once.
When taking into account that military planes usually take more risks, it does not seem unlikely that they also have tighter rules for certain procedures. Maybe someone who knows more can explain this.
PADSpot From Germany, joined Jan 2005, 1676 posts, RR: 6 Reply 10, posted (4 years 7 months 1 week 4 days 16 hours ago) and read 5713 times:
Quoting Norlander (Reply 8): Please explain that point a bit more, as I understand it military equipment doesn't need to hold to the stricter security margins of civilian use. They are not liable in the same way. To put it another way: "There is no way a plane like the SR-71 would ever be certified for civilian use".
I think you misunderstood me. A fully laden jet fighter needs to be airborne after about 1000m, because it may need the remaining 1000-1200m to come a stop if it had to reject take off. It is not like a B737 which just has to take care that the remaining runway length from the time it reaches V1 speed is sufficient to come to a stop. Jet fighters may have only one engine and are mostly incapable of take-off on a single engine when fully laden. Also jet fighter usually have less breaking power, which makes emergency arrestor systems necessary in cases of emergency. The power-to-weight-to-brakepower ratio is entirely different with jet fighters compared to commercial airliners. Thus runway requirements are different.
In other words you cannot do a "dry" take off with 5tonnes of ordnance that would take 2000m on a 2200 runway. If an engine broke down on the last meter you would be in trouble.
Zeke From Hong Kong, joined Dec 2006, 6800 posts, RR: 74 Reply 11, posted (4 years 7 months 1 week 4 days 16 hours ago) and read 5709 times:
Quoting PADSpot (Reply 7):
Runway length is fixed and military airplanes need much larger security margins compared to civil airliners as braking power is relatively much lower. Typical military runways at fighter bases are 2000-2400m. With a heavy load you simply need to be airborne after about 1000m, because otherwise you don't have enough runway left to come to safe stop in case of an rejected take-off. You can almost say required runway length is take-off distance *2.
The Jaguar technique was to pull back at the threshold markers at the other end of the runway and hope you clear the fence.
AutoThrust From Switzerland, joined Jun 2006, 1254 posts, RR: 8 Reply 12, posted (4 years 7 months 1 week 4 days 15 hours ago) and read 5695 times:
Quoting PADSpot (Reply 10): Jet fighters may have only one engine and are mostly incapable of take-off on a single engine when fully laden. Also jet fighter usually have less breaking power, which makes emergency arrestor systems necessary in cases of emergency. The power-to-weight-to-brakepower ratio is entirely different with jet fighters compared to commercial airliners.
While i mostly agree, the EF has to have good brakes because the EJ-200 on IDLE produce so much thrust, to make the plane move if the brakes aren't applied.
Second though fighters don't have thrust reversers, the Typhoon(and othe types) have a deployable brake chute, which i guess wouldn't need at a RTO 1000 meters to stop.
Rwessel From United States of America, joined Jan 2007, 1614 posts, RR: 2 Reply 13, posted (4 years 7 months 1 week 4 days 10 hours ago) and read 5649 times:
Quoting PADSpot (Reply 10): Jet fighters may have only one engine and are mostly incapable of take-off on a single engine when fully laden.
That doesn't make a lot of sense to me. Most twin engine fighters have similar (or better) MTOW wing loadings as airliners, and much more installed power.
Consider:
777-200:
MTOW: 535klbs
Engines: 2x77klbs
Wing loading: 132lbs/sqft
Single engine power loading: 6.9lbs/lb
F-15C:
MTOW: 68klbs
Engines: 2x17.5klbs dry, 2x25klbs A/B
Wing loading: 112lbs/sqft
Single engine power loading: 2.7lbs/lb
In fact the F-15 has considerably better power loading on a single engine than the 777 has on both (and only a bit worse than the 777 with a single engine "dry"). Admittedly the F-15C is near the high end of the range, but fighters tend to be severely overpowered.
PADSpot From Germany, joined Jan 2005, 1676 posts, RR: 6 Reply 14, posted (4 years 7 months 1 week 4 days 10 hours ago) and read 5642 times:
Quoting AutoThrust (Reply 12): While i mostly agree, the EF has to have good brakes because the EJ-200 on IDLE produce so much thrust, to make the plane move if the brakes aren't applied.
Ehhmm. Don't tell that to anyone who has a basic knowledge of physics. You will get a hell of a bashing
Just do that experiment with you car. Pull the hand brake really tight and try to start. If your break works it will quite hard to accelerate at all. You will need all the power to overcome the break and it will smoke and smell. Now drive 100kph on a highway and try to stop the car wit the hand brake. It will takes ages ...
Braking power increases almost linearly while the kinetic power that you need to kill with a brake has got a quadratic relation to speed. The kinetic power of 20t aircraft at 320kph is ASTRONOMICALLY BRUTE. Nevertheless even a really bad brake might be able to keep an aircraft still although you apply high levels of (dry) thrust. That's because a still aircraft has ZERO kinetic energy even if full afterburner applied. In order to keep the aircraft still the brake just needs to hold, but is does not destroy any energy. Energies are destroyed when parts of landing gear break after you drove your experiment over the top.
Second though fighters don't have thrust reversers, the Typhoon(and othe types) have a deployable brake chute, which i guess wouldn't need at a RTO 1000 meters to stop.
The Tornado has got thrust reversers. Brake chutes are optional on some types and a mere emergency measure on others. There are not so many type who deploy brake chutes as part of a normal landing.
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