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By: - 12th October 2011 at 11:42 Permalink - Edited 1st January 1970 at 01:00
The aft-tail aircraft can probably be the most 'stealthy' with the least compromise from near-optimum placement of control surfaces, which would most significantly affect the delta-canard."
Not really, a conventional tail with a single vertical stabiliser is a stealth nigthmare. It's act like a a cat eye reflector. The best choice for stealth is a clean Delta with a stacked vertical stabiliser and some continuous curvature. DERA is USA.;)
By: - 12th October 2011 at 12:46 Permalink - Edited 1st January 1970 at 01:00
DERA is USA.;)
No that would be DARPA or how it is called. DERA was the predecessor of QinetiQ.
By: - 12th October 2011 at 17:44 Permalink - Edited 1st January 1970 at 01:00
It's amusing to see how all three derivatives got rid of the long moment arm canard configuration.
By: - 12th October 2011 at 19:50 Permalink - Edited 1st January 1970 at 01:00
It is equally amusing to note that the short moment arm configuration was considered compromised in terms of control surface placement compared to the optimum for a delta canard configuration :diablo:SCNR :D
you mean that they failed to understand how to integrate it properly. :rolleyes:
By: - 12th October 2011 at 20:38 Permalink - Edited 1st January 1970 at 01:00
And you guys are oh so great aerospace engineers.:p
By: - 12th October 2011 at 21:51 Permalink - Edited 1st January 1970 at 01:00
No that would be DARPA or how it is called. DERA was the predecessor of QinetiQ.
which DARPA aircraft? got a picture?
By: - 12th October 2011 at 22:00 Permalink - Edited 1st January 1970 at 01:00
It is equally amusing to note that the short moment arm configuration was considered compromised in terms of control surface placement compared to the optimum for a delta canard configuration :diablo:SCNR :D
I think you read it wrong
"The aft-tail aircraft can probably be the most 'stealthy' with the least compromise from near-optimum placement of control surfaces"
Means that the close coupled canard's near ideal placement of the control surfaces compromises its stealthiness much more than the placement of the control surfaces on the aft-tail version.
It means that the optimum placement is actually the canard version, which happens to be closed couple and not long moment arm type.
Nic
By: - 12th October 2011 at 22:28 Permalink - Edited 1st January 1970 at 01:00
Three possible Eurofighter Typhoon derivatives briefly studied in 1999
This is perhaps a bit of a misleading title even if unintentionally as the paper itself makes no suggestion that the designs depicted are Eurofighter Typhoon derivatives.
The three designs shown are conceptual configurations which resulted from a study undertaken at the Cranfield University which explored the possibility of using an aircraft synthesis model to design a combat aircraft for minimum life-cycle cost. I suppose there are some similarities to the Typhoon in the aft fuselage and wing trailing edge of the second design, but if you step back and look at all three you will see similarities with other aircraft as well. I can see some F-22 in the first design, a resemblance to the LCA in the second design, and there's more than a dash of Gripen in that third design. ;)
Not really, a conventional tail with a single vertical stabiliser is a stealth nigthmare. It's act like a a cat eye reflector. The best choice for stealth is a clean Delta with a stacked vertical stabiliser and some continuous curvature. DERA is USA.;)
I think what other similar studies have shown, and what the current direction of manned and unmanned combat aircraft development would seem to confirm is that a tailless delta or better yet an all wing configuration has the greatest potential for all-aspect/broadband RCS reduction. The tailed design shown has a vertical tail with adjacent horizontal tail surfaces forming a 90° dihedral corner reflector, and although it shows better planform alignment than the canard-delta it still has additional control surfaces and a lower leading edge sweep than the pure delta configuration.
By: - 12th October 2011 at 23:12 Permalink - Edited 1st January 1970 at 01:00
Yes, the phrasing isn't entirely clear, but my impression is that the paper is referring to the penalty in control effectiveness incurred by moving the control surfaces to the position which is best for signature reduction on each layout. For example, with a conventional tail, the aerodynamically favourable solution would be to have them lower than the wing as on the F-15 and Su-27, while a low-RCS design would want to place them in the same plane(F-22/35). So going from long to short moment arm on the canard configuration would be considered a compromise (with more significant consequences than moving a conventional tail up) if this is the correct interpretation.
I don't know how you can extrapolate all this from this one sentence, where he is talking about the aft tail design only?
Nic
By: - 12th October 2011 at 23:59 Permalink - Edited 1st January 1970 at 01:00
What part about "... which would most significantly affect the delta-canard" did you miss?
as in "when compared to the aft-tail layout re. stealthiness.
They imply that the better you place the control surfaces the more impact it has on stealthines.
Nic
By: - 13th October 2011 at 01:39 Permalink - Edited 1st January 1970 at 01:00
It is worth noting that in the mid-1990s, when Germany was studying alternatives to save cost, cut-down Eurofighter derivatives (among them one pure delta design) were indeed considered alongside off-the-shelf solutions. So that might be where the confusion arose, if datafuser was aware of this.
Yes, as I recall there were various configurations studied and one was to delete the canards and adopt a pure delta with a cranked leading edge. There was even an image floating about that had a similar line drawn side by side comparison of the configurations proposed.
I certainly wasn't suggesting that datafuser was trying to deliberately mislead anyone, just that other posters seemed to be running with the assumption that these were actually derivatives of the Typhoon.
By: - 13th October 2011 at 07:10 Permalink - Edited 1st January 1970 at 01:00
Yes, as I recall there were various configurations studied and one was to delete the canards and adopt a pure delta with a cranked leading edge. There was even an image floating about that had a similar line drawn side by side comparison of the configurations proposed.I certainly wasn't suggesting that datafuser was trying to deliberately mislead anyone, just that other posters seemed to be running with the assumption that these were actually derivatives of the Typhoon.
Well, I should have said those three configurations are very loosely based on the Typhoon - all three have a 'twin engine, single vertical tail" configuration as well as two wingtip pods seen on the Typhoon.
The industrial arrangement - two major (UK & Germany) and two minor (Italy & Spain) partners - for producing 620 of these imaginary aircraft is exactly the same as the Typhoon's.
By: - 13th October 2011 at 10:30 Permalink - Edited 1st January 1970 at 01:00
Not really, a conventional tail with a single vertical stabiliser is a stealth nigthmare. It's act like a a cat eye reflector. The best choice for stealth is a clean Delta with a stacked vertical stabiliser and some continuous curvature. DERA is USA.;)
Actually tailless blended wing delta with no vertical stabilizers like the B-2, A-12, or proposed Boeing NGAD is the optimal stealth design.
By: - 13th October 2011 at 15:06 Permalink - Edited 1st January 1970 at 01:00
It is worth noting that in the mid-1990s, when Germany was studying alternatives to save cost, cut-down Eurofighter derivatives (among them one pure delta design) were indeed considered alongside off-the-shelf solutions. So that might be where the confusion arose, if datafuser was aware of this.
It was in 1992 and the studies were conducted by Eurofighter under the designation N/EFA (New European Fighter Aircraft). 7 different configurations were reportedly considered four of them are visible in the image below.
By: - 13th October 2011 at 16:53 Permalink - Edited 1st January 1970 at 01:00
Well, I should have said those three configurations are very loosely based on the Typhoon - all three have a 'twin engine, single vertical tail" configuration as well as two wingtip pods seen on the Typhoon.
Sorry but I have to disagree, none of the configurations shown are stated as being based on the Typhoon. There are some basic similarities with the Typhoon such as a single tail and twin engines but then you could just as easily point out such similarities with various other aircraft.
The industrial arrangement - two major (UK & Germany) and two minor (Italy & Spain) partners - for producing 620 of these imaginary aircraft is exactly the same as the Typhoon's.
Yes, now here I totally agree with you, undeniably the overall program structure has been based on the structure of Eurofighter consortium, but the designs which are shown however don't share anything but the most basic of similarities with the Eurofighter Typhoon.
By: - 17th October 2011 at 07:37 Permalink - Edited 1st January 1970 at 01:00
It was in 1992 and the studies were conducted by Eurofighter under the designation N/EFA (New European Fighter Aircraft). 7 different configurations were reportedly considered four of them are visible in the image below.
Is the original document where you got the image available online?
Posts: 479
By: datafuser - 12th October 2011 at 00:53 - Edited 2nd October 2019 at 11:40
Attached Eurofighter Typhoon derivatives are in the document "Recent Combat Aircraft Life Cycle Costing Developments within DERA" presented at the RTO AVT Specialists' Meeting on "Design for Low Cost Operation and Support", held in Ottawa, Canada, 21-22 October 1999.
These three derivatives were defined as "conventional semi stealthy high performance combat aircraft" and "The aft-tail aircraft can probably be the most 'stealthy' with the least compromise from near-optimum placement of control surfaces, which would most significantly affect the delta-canard."