Forum: F-22A Raptor

Elite Joined: Dec 19, 2005 Posts: 621 Status: Offline

sferrin wrote:

Corsair1963 wrote:

JR007 wrote:

A civilian F-104 still holds the low alt speed record, since 1977 by the way.

988.26 mph by a civilian, in a civilian aircraft. And if the “French” hadn’t screwed up with their equipment, he was averaging over 1,000 mph when their “stuff” broke. So later and with warmer temps, a civilian comes back and rips the old F-4 military record into shreds

Go Darryl!!!

I wonder what other ex-Military types mite be used in the future to break the current record held by the F-104. I believe the Tomcat and F-111 had very good Low Alt Performance! Wink

There was talk (here I think) about the F-16 being able to beat it but the USAF squashed the idea.

Interesting! I the Tornado is smaller and lighter than the two American designs. So, it maybe worth considering? Does anyone have any ideas???

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sferrin wrote:

Corsair1963 wrote:

JR007 wrote:

A civilian F-104 still holds the low alt speed record, since 1977 by the way.

988.26 mph by a civilian, in a civilian aircraft. And if the “French” hadn’t screwed up with their equipment, he was averaging over 1,000 mph when their “stuff” broke. So later and with warmer temps, a civilian comes back and rips the old F-4 military record into shreds

Go Darryl!!!

I wonder what other ex-Military types mite be used in the future to break the current record held by the F-104. I believe the Tomcat and F-111 had very good Low Alt Performance! Wink

There was talk (here I think) about the F-16 being able to beat it but the USAF squashed the idea.

I highly doubt that... F-16 doesnt have a variable inlet, thus its thrust is less at altitude.

Actually, the F-16 is extremely fast down low. What you have to understand is that the Mach number isn't that high when you're trying to break speed records at low altitude. Variable geometry inlets only give you a significant thrust advantage as your approach Mach 2. A low altitude speed record won't even reach Mach 1.5 most likely.

Veteran Joined: Jul 01, 2007 Posts: 325

Just don't try it with a block 25 or 42.

Elite Joined: Dec 14, 2005 Posts: 652 Status: Offline

SnakeHandler wrote:

Just don't try it with a block 25 or 42.

Unless it happens to be an ANG Block 42 with the new PW-229 engines they're upgrading them with...

More heat! Devil

SnakeHandler wrote:

Just don't try it with a block 25 or 42.

I heard (from a former Eagle driver, so take it for whatever you think it's worth) that the 800 KCAS limit airspeed was put in place after an early block F-16A pilot took his aircraft past 800 KCAS down on the deck causing the engine to... well... blow up? This happened due to the F100-PW-200's inability to limit compressor discharge pressure. If you got the thing too far above 800 KCAS at low altitude, the fan RPM (and possibly the compressor RPM too) would end up generating too high a pressure for the sections aft of the compressor to handle... and then boom.

I believe all F-16 powerplants with the exception of the F100-PW-200 have a pressure probe extending out in front of the fan which measures the inlet total pressure (or is it stagnation pressure?) and adjusts fan (and possibly compressor) RPM to keep the compressor discharge pressure below critical levels no matter what the flight conditions. The 800 KCAS limit airspeed was kept in place, but I don't think anyone really knows when other parts of the F-16's airframe will start failing. The canopy will likely be the first thing to fail on the airframe above 800 KCAS. How long it can withstand, say, 850 KCAS probably depends on several factors. I somehow doubt that the USAF, General Dynamics, or Lockheed Martin tested a bunch of F-16 canopies in a wind tunnel at various speeds above Mach 1.2 (standard sea level conditions) to see how long they'd hold up.

As for breaking the low altitude speed record in an F-16, the Block 30 and 40 with F110-GE-100 engines would be the worst candidates. F-16s powered by the F110-GE-100 (I'm not even considering the small-mouth Block 30s that were fitted with this engine before big inlet versions arrived on the scene) have installed thrust issues in the lower right of the flight envelope. In other words, the installed thrust for Block 30s and 40s with F110-GE-100 begins to drop off dramatically at low altitudes above Mach 1. They won't even make 800 KCAS at sea level in max AB on a standard day. The Block 50 with F110-GE-129 does not suffer from the same issue. In fact, one of the major issues addressed by the -129 was low altitude installed thrust performance above the Mach. All F-16 variants with the exception of the Block 30 and 40 powered by the F110-GE-100 are able to make at least 800 KCAS at sea level standard conditions.

The best contenders for the low altitude speed record (as far as F-16s go) are the Block 50 (F110-GE-129) and Block 52 (F100-PW-229). I would assume that the Block 60 with F110-GE-132 is at least equal in low altitude performance to the Block 50, so throw that in the mix too. The thing about breaking low altitude speed records is that you're pushing the limit of at least one of the airframe's components. Fit the F-16 with an aluminum canopy and a virtual reality picture of the world and it might very well reach 875-900 KCAS. The Block 50 or 52 can easily break 800 KCAS in max AB. You'd have to be a fool, however, to go for a low altitude speed record in a stock F-16. Imagine having the canopy fail on you while you're doing in excess of 850 KCAS at sea level! Yipes!

What's the current low altitude record holder in terms of indicated/calibrated airspeed?

Elite Joined: Dec 14, 2005 Posts: 652 Status: Offline

Raptor_One wrote:

..the 800 KCAS limit airspeed was put in place after an early block F-16A pilot took his aircraft past 800 KCAS down on the deck causing the engine to... well... blow up? This happened due to the F100-PW-200's inability to limit compressor discharge pressure. If you got the thing too far above 800 KCAS at low altitude, the fan RPM (and possibly the compressor RPM too) would end up generating too high a pressure for the sections aft of the compressor to handle... and then boom.

I haven't heard that one, but who knows!? Shrug

But it is true the engine can fail at high speed low altitude if compressor discharge pressure isn't kept within limits. The diffuser case is more likely to actually fail in such a situation but same net result... BOOM! Shocked

Raptor_One wrote:

..I believe all F-16 powerplants with the exception of the F100-PW-200 have a pressure probe extending out in front of the fan which measures the inlet total pressure (or is it stagnation pressure?) and adjusts fan (and possibly compressor) RPM to keep the compressor discharge pressure below critical levels no matter what the flight conditions.

The probe may have not pointed out the front of the engine, but there is an inlet pressure reading taken for the engine's control system and pilot instruments. Inlet and Exhaust pressures are used to calculate Engine Pressure Ratio (EPR). I'll have to dig out some old books to confirm but I believe the Electronic Engine Control (EEC) of the PW-200 had compressor discharge pressure limits as part it's logic. (I will get back with everyone soon)

Raptor_One wrote:

..The best contenders for the low altitude speed record (as far as F-16s go) are the Block 50 (F110-GE-129) and Block 52 (F100-PW-229). I would assume that the Block 60 with F110-GE-132 is at least equal in low altitude performance to the Block 50, so throw that in the mix too.

Again, don't forget the Block 42s that the ANG folks have modified with PW-229 engines. These 42s are lighter than 52s and are said to be a hotter Viper than Block 52... (but then again who truly knows except for the guys/gals flying them?) Shrug

I'd love to see an A model with a PW-229 in it! In Love

Elite Joined: Dec 19, 2005 Posts: 621 Status: Offline

Raptor_One wrote:

SnakeHandler wrote:

Just don't try it with a block 25 or 42.

I heard (from a former Eagle driver, so take it for whatever you think it's worth) that the 800 KCAS limit airspeed was put in place after an early block F-16A pilot took his aircraft past 800 KCAS down on the deck causing the engine to... well... blow up? This happened due to the F100-PW-200's inability to limit compressor discharge pressure. If you got the thing too far above 800 KCAS at low altitude, the fan RPM (and possibly the compressor RPM too) would end up generating too high a pressure for the sections aft of the compressor to handle... and then boom.

I believe all F-16 powerplants with the exception of the F100-PW-200 have a pressure probe extending out in front of the fan which measures the inlet total pressure (or is it stagnation pressure?) and adjusts fan (and possibly compressor) RPM to keep the compressor discharge pressure below critical levels no matter what the flight conditions. The 800 KCAS limit airspeed was kept in place, but I don't think anyone really knows when other parts of the F-16's airframe will start failing. The canopy will likely be the first thing to fail on the airframe above 800 KCAS. How long it can withstand, say, 850 KCAS probably depends on several factors. I somehow doubt that the USAF, General Dynamics, or Lockheed Martin tested a bunch of F-16 canopies in a wind tunnel at various speeds above Mach 1.2 (standard sea level conditions) to see how long they'd hold up.

As for breaking the low altitude speed record in an F-16, the Block 30 and 40 with F110-GE-100 engines would be the worst candidates. F-16s powered by the F110-GE-100 (I'm not even considering the small-mouth Block 30s that were fitted with this engine before big inlet versions arrived on the scene) have installed thrust issues in the lower right of the flight envelope. In other words, the installed thrust for Block 30s and 40s with F110-GE-100 begins to drop off dramatically at low altitudes above Mach 1. They won't even make 800 KCAS at sea level in max AB on a standard day. The Block 50 with F110-GE-129 does not suffer from the same issue. In fact, one of the major issues addressed by the -129 was low altitude installed thrust performance above the Mach. All F-16 variants with the exception of the Block 30 and 40 powered by the F110-GE-100 are able to make at least 800 KCAS at sea level standard conditions.

The best contenders for the low altitude speed record (as far as F-16s go) are the Block 50 (F110-GE-129) and Block 52 (F100-PW-229). I would assume that the Block 60 with F110-GE-132 is at least equal in low altitude performance to the Block 50, so throw that in the mix too. The thing about breaking low altitude speed records is that you're pushing the limit of at least one of the airframe's components. Fit the F-16 with an aluminum canopy and a virtual reality picture of the world and it might very well reach 875-900 KCAS. The Block 50 or 52 can easily break 800 KCAS in max AB. You'd have to be a fool, however, to go for a low altitude speed record in a stock F-16. Imagine having the canopy fail on you while you're doing in excess of 850 KCAS at sea level! Yipes!

What's the current low altitude record holder in terms of indicated/calibrated airspeed?

How would that problem effect F-15's equipped with P & W F-100's at Low Alt?

When it comes to maximum speed (especially at low altitude), a few hundred pounds or even a thousand pounds or more makes little difference. The angle of attack at Mach 1.2+ down on the deck is going to be extremely low during level flight. The difference in trim drag due to slightly different static margins from one block to the next will also be minimal at Mach 1.2+ speed (the aircraft is not unstable at this speed either). To maintain level flight, you need to have your lift = your weight. At Mach 1.2+ at sea level, you're generating a huge amount of lift at a very low AoA. An extra 1000 lbs of lift necessary to maintain level flight for a heavier Block 50 or 52 (compared to a 42 with PW-229) would amount to a small fraction of a single degree of angle of attack at Mach 1.2+. The added drag from this super small increase in AoA would be insignificant. In fact, the drag coefficient may be constant (or nearly so) throughout this small change in angle of attack. Of course the lighter plane will accelerate faster, but it will top out at the nearly the exact same speed given identical aerodynamics and installed thrust.

Veteran Joined: Jul 01, 2007 Posts: 325

I guess I missed the segway. How did we go from time to climb to low level dashes, again?

Elite Joined: Dec 19, 2005 Posts: 621 Status: Offline

SnakeHandler wrote:

I guess I missed the segway. How did we go from time to climb to low level dashes, again?

I don't know...........but you have to admit its more interesting! Wink

Newbie Joined: Oct 04, 2007 Posts: 5 Status: Offline

According to "Air Forces of the World", Crescent Books, 1990, author Christopher Chant, the F-14, F-15, F-16, and F-111 all have a max sea level (or 1000 ft alt) speed of 910-915 mph, or mach 1.2. The Tornado IDS is listed as having a sea level speed of 980+, or almost mach 1.3. So, as our friend mentioned above, the Tornado would be the most likely candidate of "current" jet fighters to take the low altitude record from the Starfighter.

Interestingly, all of the modern high performance jet fighters (1990 current) listed in that book have a max sea level speed well under 1000 mph with the exception of the Tornado. This, I'd guess, is entirely due to the variable geometry wings. Yes, the F-111 and F-14 have them also, but they both have much higher drag wings and much larger airframes. The Tornado was designed from the outset for low level penetration work.

I'm not an aerodynamic engineer, but I'd venture to guess that 1000 mph is the approximate limit for a manned airfoil in a 15 psi atmosphere.

Oh, and the reason we ended up back on low alt speed records was my bringing the Starfighter back into the TTC discussion. I love this little plane. It has the most efficient high speed wing and fuselage ever put into a production fighter. The only reason it doesn't hold every speed and climb record is due to a lack of engine power. Give it a ~25K lb st motor and it will own all the records again.

Elite Joined: Jul 22, 2005 Posts: 915 Status: Offline

Then there was Project Pluto. Thousands of miles at Mach 3 -4 at 1000 ft. Shocked

(Sorry for the drift but the low drag at low altutude comment reminded me off it. According to one of the reports on it added weight effected drag very little.)

Elite Joined: Jul 20, 2005 Posts: 1021 Status: Offline

It never flew in Project Pluto...

Elite Joined: Dec 14, 2005 Posts: 652 Status: Offline

sferrin wrote:

Then there was Project Pluto. Thousands of miles at Mach 3 -4 at 1000 ft. Shocked

(Sorry for the drift but the low drag at low altutude comment reminded me off it. According to one of the reports on it added weight effected drag very little.)

I remember reading about Project Pluto in an Air&Space Magizine years ago...

Here is some of it's Wikipedia article:

"Once powered up, the unshielded half-gigawatt nuclear reactor would emit highly lethal radiation in a large radius; such a vehicle could not possibly be human-piloted or reused. Indeed, some questioned whether a cruise missile derived from Project Pluto would need a warhead at all; the radiation from its engine, coupled with the shock wave that would be produced by flying at Mach 3 at treetop level, would have left a wide path of destruction wherever it went. The SLAM as proposed would carry a payload of many nuclear weapons to be dropped on multiple targets, making the cruise missile into an unmanned bomber. Contrary to some reports, the exhaust of the engine would not itself be highly radioactive."

If anyone is interested; check out this site... WOW! Shocked

http://www.bisbos.com/rocketscience/air ... actor.html

Forum: F-22A Raptor

Time-to-climb record attempt - F-22A Raptor