FXX and LWF: Lightweight Fighter propositions in the early 1970s

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Blacktail

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I was reading about Col. John Boyd's FXX requirement a while back, which resulted in the LWF project (which, in turn, resulted in the YF-16 and YF-17). It seems that the aircraft Boyd specified for was actually markedly different than the ones the USAF would allow to qualify. Specifically, what he wanted in the FXX was;
- A gun
- 2 wingtip missile rails
- No other weapon stations
- An F100 turbofan
- A bubble canopy
- Ranging radar only
- No ECMs

...and that's it.

The resulting design actually ended up having twice the range of the F-15A Eagle on less than half the fuel and half the engines, because it had an extremely high capacity of fuel compared to it's empty weight (i.e., a large Fuel Fraction --- and man, did the USAF brass flip their lids when they found out!).

Here's the thing, though. I've only heard the original FXX specifications briefly mentioned in passing; I've never seen them, nor any official artwork, schematics, models, and so on.

Even more disappointing is that the sources in question are the "Lightweight Fighter Mafia" themselves. You would think they would have had more information on such a huge undertaking! After all, an aircraft like this sure wouldn't be popular with the establishment (and they unsurprisingly hated it with a passion, doing everything they could to sabotage the project), but the final result *still* ended up becoming an operational warplane; the F-16 Fighting Falcon.

We all know what happened from there, but what about the early FXX designs? This is what I'm interested in.

Does anyone else know more about this subject?
 
PaulMM (Overscan) said:
http://www.secretprojects.co.uk/forum/index.php/topic,20070.msg195298.html#msg195298
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Well, that covers Northrop's involvement in FXX and LWF!

But what about the other contenders? I know that General Dynamics (obviously), Vought, and Boeing had proposals as well.
 
In June 1969, Sprey's paper "F-XX and VF-XX - Feasible High Performance Low Cost Fighter Alternatives" used the Northrop N-700 P-530 variant [perhaps N310 / P700?] and General Dynamics FX-404 designs to substantiate their work. Riccioni's "Falcon Brief" in 1971 used the Boeing 909-618, Northrop N314-2 (another P-530 version), and a General Dynamics 401(?) design [Stevenson gives FW71-274-VG1369 which is a drawing number not a model number] to illustrate his concepts.
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Blacktail said:
It seems that the aircraft Boyd specified for was actually markedly different than the ones the USAF would allow to qualify.
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I think this concept was nicknamed "Red Bird," which differed significantly from the concept aircraft that they were studying that eventually led to the F-15, which was nicknamed the "Blue Bird."

"The reason the Air Force ignored Red Bird was that the service saw it as a small, simple fighter with short range and limited load-carrying capability, and the Air Force had previous bad experiences with such aircraft. Range was the major issue. Small fighters carried a small amount of fuel, so they had limited endurance. This meant their patrol time was limited and they were not able to escort long-range bombers. Additionally, small aircraft had to keep their weight down so they could only carry limited armament, radar, electronic countermeasures, and other systems the Air Force deemed necessary for modern air combat, especially based on their experiences over North Vietnam. The Air Force had looked at two small fighters, the F-104 in the 1950s and the Northrop F-5 in the 1960s, but combat tests in Vietnam confirmed that both the F-104 and the F-5 had too short a range and too light a payload to be useful." THE REVOLT OF THE MAJORS: HOW THE AIR FORCE CHANGED AFTER VIETNAM - Marshall Michel (2006)
 
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Can anyone on this website come up with any designs & artwork/concept art for a Red Bird style aircraft please? It’s for a designchallenge for making a future pair of compact low cost low maintenance ruggedly high reliability low maintenance air superiority fighters that can operate in similar fashion to the Mig-21s & Jas-39s away from populated areas which means operating from ice snow sand swamps rivers streams oceans mountains rainforests rocky cliffs roads highways volcanoes lava etc. it means I would honestly love to see an aircraft being able to operate from volcanoes with fully retractable ski undercarriage
 
Although, not necessarily Red Bird, Harry Hillaker of General Dynamics, who discussed with Boyd the EM theory and the design of an EM fighter concept developed this early concept in 1965. A single engine concept emerged in 1968 that was a single engine variant. The early design has influences of the Hillaker's early F-111 design.

"My first dealings with John Boyd and Pierre Sprey did not involve any airplane designs per se. Our early work was purely and simply an analysis of the relationships of wing loading and thrust loading and fuel fraction (the ratio of fuel capacity to the weight of the airplane). We wanted to understand the relationship between these variables. We knew that we wanted low wing loading and high thrust loading. But we also knew that low wing loading means more weight and more drag. High thrust loading means high fuel consumption. Airplanes with high thrust-to-weight ratios are normally equated with short range. That's why we started looking at fuel fractions. We wanted to tie all these things together to get a better feel for the boundaries involved."

"I would say that people had thought about it, but no one had applied it systematically to get a complete picture.
We were trying to determine the trends. We didn't spend a lot of time looking for exact values. It is one thing to agree that something is better. But how much better is another question. The answer involves finding a trend and asking more questions. Is the design being improved by these actions? How fast is it improving for a given amount of change? The person most responsible for this approach was John Boyd."

"People tend to focus on one part of a given parameter. You can, for example, get a higher thrust-to-weight ratio by increasing the thrust. You can also get a higher thrust-to-weight ratio by leaving the thrust alone and reducing the weight, which is what we did on the lightweight fighter."

"We had to take this approach because we had to use a given engine, the F100, which had been developed for the F-15. John Boyd had played a part in defining that engine, and he felt comfortable with it. So the engine was fixed. That meant that the thrust was fixed. If we wanted a high thrust-to-weight ratio, we had no choice but to reduce weight."

"The range equation can be treated like the thrust-to-weight ratio. The typical approach to increase range is to simply increase fuel capacity. But increasing fuel capacity increases volume, which means more weight and more drag. People think that big is better. It's not. With the lightweight fighter, we wanted to achieve our ends through different means. We increased range by reducing size."

Harry Hillaker interview http://www.codeonemagazine.com/article.html?item_id=37
 

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overscan (PaulMM) said:
Fighterreaper97 said:
it means I would honestly love to see an aircraft being able to operate from volcanoes with fully retractable ski undercarriage
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I have no idea how you expect to operate an aircraft from volcanoes. The mind truly boggles. Active volcanoes? Lava-proof ski undercarriage?
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Can you fly that plane and land it, out of a volcano ?

View: https://www.youtube.com/watch?v=dycYPvcP-Tk


View: https://www.youtube.com/watch?v=lm8fYf53SMg
 

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