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Airframe in General Print E-mail
(17 votes, average 4.24 out of 5)
Written by Sabc   
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Compared to an average fighter, the F-15E is a very large aircraft, 70 feet long and 42 feet wide. It is more or less the same size as a B-25 bomber from World War II. It's a twin-engined, twin-tailed construction, it has fixed-geometry, swept wings which are shoulder-mounted. The wing surface is exceptionally large, resulting in a very low wing loading, which is a key factor for good turning performance.

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The fuselage is an all-metal semi-monocoque construction, consisting of a central pod and twin aft booms outside the twin engine exhausts. The following figure illustrates the material distribution in the F-15E. The composite materials displayed dark grey on the figure below are carbon/epoxy in the speed brake (aft of the cockpit, around the middle of the airframe) and boron/epoxy in the vertical stabilizers, rudders and horizontal stabilizers

 

Materials used in the aircraft are of the following distribution (percentages below are given by weight):

Material Type Weight %
Aluminium
Steel
Titanium
Composites (boron, graphite)
Fiberglass
Other
37.3 %
5.5 %
25.8 %
1.2 %
1.0 %
29.2 %

 

Parts that are put to great tear and wear and high temperatures are made of titanium, mostly around the engines and in the inboard sections of the wings. The entire rear fuselage section is made of superplastic-formed and diffusion-bonded titanium. Titanium-made sections are the following

  • Three main wing spars
  • Connecting bulkheads to the main wing spars
  • Engine bay frames
  • Fuselage skin aft of the forward main wing spar
  • Cantilever booms outboard of each engine which carry the twin fins and horizontal Stabilizers
  • Stabilizer attachments
  • Spars of the fins
  • Firewall between the two engines (to prevent fire in one engine from spreading to the other)

The heart of the aircraft structure is a set of four carry-through frames which run across the central fuselage, each with holes cut into them to allow the engine air intake ducts to pass through. At each end, they form the main attachment points for the wings, the three aft frames being attached to the three wing spars (made of titanium), and the forward point attaching to a leading-edge member. Machined titanium frames in the rear fuselage maintain structural integrity and provide the main mountings for the engine installation.

The structure of the aircraft is stronger compared to other F-15 models (A to D), it can safely operate at takeoff weights as great as 81,000 pounds, can withstand 9G load when turning and is cleared for 16,000 hours, double the lifetime of earlier F-15's.

Space for additional avionics is provided at the expense of a slight decrease in internal fuel capacity. Internal fuel is stored in eight individual internal Fuel Tanks, located in the main inter-spar areas of the wing and in the center section of the fuselage between the air intakes. Besides three optional external fuel tanks (two under the wings and one on the centerline pylon under the fuselage), all F-15E's can be (and most of time are) fitted with conformal fuel tanks (CFT's), each of which is not just storing extra fuel but equipped with six tangential hardpoints.

Sources

Dennis R. Jenkins:

McDonnell-Douglas F-15 Eagle - Supreme Heavy Weight Fighter

1998, Aerofax, ISBN 1 857800 81 8

Paperback, 8.5" x 11" (21.5 cm x 28 cm), 112 pages, over 250 images

Without a doubt the finest air fighter in service with western air forces, the F-15, still in production (now under the Boeing name) is meeting export orders for Israel and Saudi Arabia with interdictor variants. This book includes in-depth coverage of systems, engines, weapons, development usage and all 20 test aircraft. Recommended for F-15 enthusiasts.

F-15E.info rating: HIGHLY RECOMMENDED

 

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Last Updated on Monday, 30 May 2011
 


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Discuss (4 posts)
Re:Airframe in General
Jul 14 2011 12:33:55
Hi there anyone is experience in nose landing gear vibration in the F15E?
#471
Re:Airframe in General
Jul 16 2011 21:26:47
First of all, welcome to the SEF!
As for your question, I'm not sure what you want to know. There is a small metal rod attached to the main gear strut, right above the wheel. Its purpose is to reduce vibration during taxiing by simply adding extra weight to the lower end of the gear. See attached image...
#472
Re:Airframe in General
Jul 21 2011 05:53:46
yes i do know that there is a shimmy mass damper to reduce the vibration cause. is there any possible causes as recently what we have done to cure the vibration is by reservcing the sturt, change the nose steering unit. It still doesn't cure it and lastly we change out the strut itself. We did some dimension check on the strut itself and all are within the tech order limits.
#473
Re:Airframe in General
Jul 24 2011 17:47:12
Wow, that's well beyond my competence. I hope some of our ground crew members have an answer to this.
#478

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