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Aircraft Vs Thread 4


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Well, the F-16 has an angled seat, said to give like .5 or .75 extra G's of "resistance" for the pilot.

Fact: (AFAIK). It was not designed that way because of G's, nor did they expect such a benefit. It was the only way to fit the seat under such a low canopy.

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Well, the F-16 has an angled seat, said to give like .5 or .75 extra G's of "resistance" for the pilot.

Fact: (AFAIK). It was not designed that way because of G's, nor did they expect such a benefit. It was the only way to fit the seat under such a low canopy.

That is correct sir on both counts. When GD originally designed the F-16 the ACES-2 was still in development so the side rails were an unknown. The seat mounting was then redesigned after the full specs were revealed in order to make the seat fit inside the cockpit tub that was designed and not hit the canopy. The extra G tolerance was a happy offshoot.

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i had a question pop in to my head while i was working. it may have been already covered. but would piloting lieing down as opposed to being seated help in any way at reducing the effects of gs?

Eric "Winkle" Brown, the great British test pilot, was an advocate of this arrangement and IIRC tests have shown that it increases "G"-tolerance.

David r.e. Lightning - we had to protect the domestic industry somehow... :lol:

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David r.e. Lightning - we had to protect the domestic industry somehow... :lol:

One would think that the biggest threat to your domestic industry would be the Luftwaffe, and properly functioning P-38s would have been useful for that.

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Low-alt, high-speed B-52 pass:

That's nothing compared to what this guy did with the B-52 (of course before it got him and three other officers killed):

http://www.youtube.com/watch?v=UJb08ZzejAA...feature=related

http://www.youtube.com/watch?v=sjFIB1L3BPU

In the case of the photo op at that bombing range he comes within about 30 feet of hitting the ridge where the photographers were... allegedly on one pass he came within THREE Feet of hitting the ground.

Edited by Apollo Leader
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That B-52 video reminded me of the story of the RB-47 and the Mackinac bridge... I would have loved to seen such a thing...

http://www.absolutemichigan.com/dig/michig...ath-the-bridge/

http://akkingfish.homestead.com/files/lappo.html

Now that would have been cool if a photo or film existed of that stunt.

Edited by Apollo Leader
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I hope I can post this question here, since it is aircraft related.

I've been having some fun converting most of the older Valkyries thrust outputs measured in kg units into kN, which is used for the new Macross Zero statistics. It's interesting to compare the older Valkyries (in-fiction "newer") with the Macross Zero Valkyries. Anyway, this got me interested in real world comparisons as well, so I've been looking up statistics for the F-15, F-22, Su-30, F-35, A-10 and a bunch of my other favorite planes and comparing them to the Valkyries. Needless to say, it's no wonder the Valkyries are so amazing. They often have many times more thrust than traditional planes yet weigh only half as much.

So then the idea hit me to compare thrust-to-weight ratios. Just one problem; I don't know how. I can do the formula's well enough, but my math must be sloppy because I can't get the numbers right. How does one properly determine the thrust-to-weight ratio of a fighter?

Edited by Mr March
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As simple as it gets. Total thrust of the engines divided by weight of the plane. Bigger is better. Numbers above 1 allow straight up flight.

The issue is--what weight? Empty, max takeoff, or "typical combat load"? There is a defined standard for "combat load", but few people use/agree with it. Something like 1/2 weapons and 3/4 fuel.

And some people like to do the opposite, which is weight-per-thrust units, where lower numbers are better. (In other words, how many pounds of plane must each unit of power carry). (based off the common "pounds per horsepower" measurement of cars)

PS---converting kg to Kn? Are you sure? I've never seen engines measured in kg. That's not technically a valid measurement unit for thrust---mass vs force. I'm betting someone got confused somewhere, and figured since a "pound of thrust" was valid, that you could just divide it by 2.205 and get a "kilogram of thrust"---but it doesn't work that way.

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Wow, I was using a much more complicated formula. Now I feel stupid :)

So the F-15 Eagle produces 155.24 kN and 12,700 kg empty weight you get a result of .01222 expressed as 1.2 I would guess. I guess I have to use emptry weight, but as you say, who knows for sure. The statistics on the wiki has the F-15 at a 1.12 thrust to weight ratio. Gawd knows how the hell they came to that :)

So if the VF-1 produces 225.4 kN and weighs 13,250 kg you get 1.7 thrust to weight ratio or 3.4 thrust to weight ratio with afterburners. Sexah :)

Regarding kg (kilo-gram force) for engine thrust (now it's time for me to act smart, lol):

It's a measurement rarely used and not recognized as an official SI. It was used in early German rocketry and by the Russians (I think China still uses it too). Since kg was used as the unit of force for all the Macross Valkyrie statistics (until the release of Macross Zero which FINALLY started using the proper kN units) one has to convert everything in order to properly compare. Grrr! Perhaps Kawamori and Co. thought kgf sounded more futuristic or perhaps Japan is yet another country that uses this silly unit rating for thrust.

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An empty F-15C has about a 1.7 thrust-to-weight ratio.

Here's a page with LOTS of weights for the F-15 variants: http://jsbsim.sourceforge.net/F15.html

Where are you getting 155 kn for an F-15's thrust? That's well below the lowest spec. I get 208 kn for a -220 engine. (23,400lbs x2, divided by 2.205, times 9.8, divided by 1000).

Again, metric and kilograms won't calculate out nicely if you don't have the same unit of measurement. If you want a "proper" 1.7 thrust to weight ratio for an empty 15C, you need the following:

208 kn of thrust. 208,000 newtons of thrust.

12,700kg of weight. Times 9.8 to get newtons. 124,460 newtons of weight.

208,000 divided by 124,460 is 1.67. (Numbers vary depending on your source--I don't have my best F-15 book handy to get "authoritative" numbers)

See, a pound of thrust is the exact same unit as a pound of weight. But a kilogram and kilonewton are not the same---you have to take into account the force of gravity.

Thus, part of the reason aviation still uses English measurements. :)

A "combat load" F-15C is right around 1, or just above it. A fully loaded F-15 can drop down to .6 (which is sad, considering some airliners hit .4)

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I just used the wiki information. That's weird that they use the max afterburner thrust for the thrust to weight ration for the F-15C. I would have thought the dry thrust would be more appropriate. :wacko: But I'm out of my element here, so I'll just go with the flow :)

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Oh no, use afterburner. You go with the max thrust regardless of how it's achieved. Omitting afterburner is kind of like saying "this car has 200horsepower, because we're not going to count the extra 40 it gets from the supercharger, because it's sometimes bypassed and not always available"

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Will do. Wow, the thrust ratios are going to be insane. The VF-1's 3.4 is just the tip of the iceberg. Although, the later Valkyrie statistics don't have overboost ratings :( Well, I suppose when you have the YF-19 with a thrust to weight ratio of 9.56, it doesn't really matter :)

Thanks a lot for the help DH. I'll know where to come if I have some more questions.

Edited by Mr March
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Langley's F-22's have reached FULL operational capability as of yesterday. (Means they can actually be deployed overseas)

"Super Gripen" going ahead. It's going to rock. Super Hornet engine, and AESA radar. Amazingly enough, the new engine is cheaper than the current Gripen engine despite having 21% more thrust. And requires no intake changes to accomodate it. Expected to fly in 2008.

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Langley's F-22's have reached FULL operational capability as of yesterday. (Means they can actually be deployed overseas)

Great info. I was wondering when the 1st Fighter Wing was going to reach full operational status with the F-22. I hear that the next to get the F-22 is Elmendorf AFB, Alaska.

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Sometimes I wish I didn't ^_^

My father spent 12 of his 22 years in the Air Force working on the B-52 and still has friends in the USAF. I get to here about whats happening with the B-52 every time I talk to him. :lol:

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I just did a search on F-14's for the VX-9 squadron on Airliners.net, and I am appalled at what they did with the "Vandy-1"!!!! The VERY last built F-14D that was sent to the VX-9 squad, the all black with bunny logo, has been stripped of paint and painted up in the CAG colors of the Pukin' Dog's!!!!!

BLASPHEMY!!!!!!!!!!!!!

There's 3 pics on there. 1 during the strip down I believe, and the other two of it all restored and in the new colors.

:angry:

HERE

is the link

Edited by Fatalist
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So if the VF-1 produces 225.4 kN and weighs 13,250 kg you get 1.7 thrust to weight ratio or 3.4 thrust to weight ratio with afterburners.

According to the line art on your site, afterburners on a VF-1 is 125% (cannot set to over 100% in the sim version that I currently downloaded, so the figures are done at maximum or 100%) power and 200% is in over boost.

The thrust obtained from redlining your jets should not be included in the thrust to weight ratio.

Since engines are not run at their peak power for longevity's sake unless their is a war on or an emergency, there is no reason to add power that is more than likely to be unavailable to the operator (or broken feature in the sim).

I digress. Thrust to weight ratio of the VF-1 (dry) in afterburner (125% power) is 2.2:1.

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Most F-14 fans are aware of what they did to the last F-14 ever built. I believe it has been repainted yet again. Black Aces on one side (who didn't even HAVE F-14D's) and I think the Black Lions on the other.

Well excuse the hell out of me for not being in the know.

Jerk

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