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Postwar Aircraft Projects / Re: Dassault Mirage G8A / ACF / Super Mirage
« Last post by hesham on Today at 08:20:12 am »
From le Fana 3/2018.
Any original drawing of the bf 109 S? I can't find the topic with those drawing,and I just want to know for wich version the wing was assigned(the F or the E?).

According to an A.I.2(g) report of December 1944 by G E F Proctor, under 'mainplanes': "The wing is very similar in construction to that employed on the Me 109 G-6 but has the following modifications:
(a) The fitting of an air duct between the main spar and the subsidiary spar to which the flaps and ailerons are attached.
(b) Wing flaps extending to root end of wing.
(c) Leading-edge slat throughout the complete span.
The air discharge is directed above the leading-edges of the ailerons and flaps, the width of the discharge slot being found by trial and error. Four widths of slot are available. The air ducts in the wing preclude the use of the normal coolant radiators and an evaporative cooling system has been evolved."
Any original drawing of the bf 109 S? I can't find the topic with those drawing,and I just want to know for wich version the wing was assigned(the F or the E?).
Space Projects / Re: Dream Chaser for CEV requirement
« Last post by bobbymike on Yesterday at 06:09:48 pm »

COLORADO SPRINGS—Sierra Nevada expects to receive aeroshell panels next month for the first orbital Dream Chaser, marking a key milestone in the run-up to the start of spaceplane assembly at the company’s Louisville, Colorado, facility.

The panels, along with the vehicle’s composite primary structure, are produced by Lockheed Martin, and form the bulk of the vehicle’s aerodynamic surfaces. The structural elements are coming together as Sierra Nevada continues through critical design review (CDR), the final phases of which are expected to be completed in July.
Missile Projects / Re: Hypersonic Conventional Strike Weapon (HCSW)
« Last post by sferrin on Yesterday at 01:44:12 pm »
Hydrogen fuel for a tactical air-launched, expendable?
Supposedly they've taken to Methane of late, but your point largely stands.

Liquid is bad enough for a weapon but make it cryogenic as well and you may as well forget it.
When those pics came up on FB, there were other pics included in the series/album, incl one of a vanilla sample the landcruiser vehicles used later by the the "pathfinder" guys in the early 80's round Ops Protea,circa 82 or thereabouts.

If I recall correctly the team were trying out a variety of vehicle/weapon combos as concepts for an envisaged AT component for airborne forces.
Postwar Aircraft Projects / Re: Lockheed AH-56 Cheyenne and derivatives
« Last post by yasotay on Yesterday at 11:24:53 am »
Does an X2 compound rotorcraft have an advantage over tilt-rotor when flying in contested environments?

I can only think of two.
  • The X2 doesn't have a translation time for the rotors to go from vertical to horizontal. I don't know how fast the tiltrotors can convert or if there are maneuvering restrictions during translation, but in the abstract I'd consider that a disadvantage.
  • The X2, if equipped with door gunners, doesn't have as much firing arc restriction as a tiltrotor would have while flying in airplane mode. Or, for that matter, in helicopter mode, since the TR's rotor disc spans out much wider than the X2.

Regarding acceleration, speculation is that starting from a steady state hover, a comparable X2 would have an acceleration advantage at the beginning  because while its pusher is smaller than the proprotors on a comparable Tilt-Rotor, it is already in position to provide full thrust.  The Tilt-Rotor would accelerate at first like a normal helicopter.  As speed increased, the more towards the horizontal the proprotors translate, the more aft thrust they're going to provide and they will surpass the thrust of the pusher by a good bit, which would up the acceleration significantly.  One advantage there is that once wingborne, 100% of the engine's power is available for thrust, whereas with an X2 the majority of power is always going to keep the thing in the air. 

Transition time will be a function of what the required performance for a give bird is, and how the engineers choose to meet it.   There are no maneuvering restrictions during transition (either way) inherent in Tilt-Rotor technology, AFAIK. 

Although neither an X2 or a Tilt-Rotor are going to be using door guns when they are traveling at their higher speeds, unquestionably at lower speeds a Tilt-Rotor has a wider rotor arc so consequently can't  elevate the door guns as far, which would be relevant in a tight bank.  Helicopters have shot themselves down by inadvertently firing through the rotor arc. 

Other possible X2 advantage , depending on the size of the vehicle, could be weight and lift efficiency  at very low speeds/hover.  With a Tilt-Rotor, the wing is always there.  As the vehicle gets smaller, the weight of the wing becomes a larger percentage of total vehicle weight so the helicopter, lacking a wing gains and advantage.  I am saying helicopter because given the extra weight of two vs one rotor, that big mast and big transmission inherent to X2, I don't know know how much those factor into the weight equation for X2. 

Again, the Tilt-Rotor always has that wing there.  That wing, while providing  very efficient lift in wingborne flight relative to a rotor, is always going to be in the downwash when in rotorborne flight.  This is going to cause a hit to Tilt-Rotor's low speed/hover efficiency.  Some of this can be mitigated because a Tilt-Rotor can put a lot more twist on its blades (because it doesn't have to push the blades through the air sideways at higher speeds), but it's not enough to overcome the penalty of wing in the downwash while rotorborne.

Superb analysis.

I will see you and raise you two.

a.  Tilt rotor wing provides sunk cost space for things like jammer/aux fuel/(restricted) weapon pods location
b.  Tilt rotor can trail things behind it like refuel hose& drogue, countermeasures or antenna.

Now before F-14D calls my raise, I do realize that the question regarded mostly hover and acceleration.  I would offer that IF the Tilt Rotor has more rotor flexibility (exact term alludes me at the moment), and nacelle rotational speed it will move out better than a conventional helicopter, without necessity to change fuselage pitch angle.  Given a standing straight line start I would have to agree that the compound would initially out accelerate the tilt rotor.  However, in practical terms since we are talking about leaving a landing zone, we have to consider that most have obstacles around them that must be cleared as well.  So with an "up and out", I am not sure there is much difference between the two honestly (given all power performance is equal).
Army Projects / Re: Trommsdorff Projects WW2
« Last post by fightingirish on Yesterday at 11:05:09 am »
In the latest German Bookazine "Fliegerrevue X"is an article about the Trommsdorff D-6000 ramjet cruise missile.
Space Projects / Re: Wernher von Braun "Round-The-Moon ship"
« Last post by merriman on Yesterday at 10:58:36 am »
Three more representations of the von Braun style of thermal control

Missile Projects / Re: Hypersonic Conventional Strike Weapon (HCSW)
« Last post by Moose on Yesterday at 10:45:18 am »
Hydrogen fuel for a tactical air-launched, expendable?
Supposedly they've taken to Methane of late, but your point largely stands.
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