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Space Projects / Re: Stratolaunch
« Last post by martinbayer on Today at 07:16:55 am »
I do think that air launch could potentially make just enough difference (90% PMF vs. 94% - the STS ET had a PMF of 96%) to make a single stage orbiter a la Interim Hotol feasible.

No, because a tank/vehicle is going to have a much lower PMF due to the difference in loads for horizontal launch

Once again, it comes down to the specific numbers of an eventual design, i.e. whether the difference between the required 90% PMF and the ET 96% PMF allows to integrate all required additional systems and modifications plus a meaningful payload. For concrete analyses, I recommend to look at the AIAA Papers 1979-879, "Utility of High Bypass Turbofans for a Two-Stage Space Transport", by Len Cormier (formerly of North American Aviation, where he was project engineer for space transportation systems at the Los Angeles Division for several years), and 1991-5006, "The An-225/Interim Hotol Launch Vehicle", by Robert Parkinson (who started his career working on propulsion systems for rocket engines and missiles at the Rocket Propulsion Establishment, Westcott, before moving to industry and at the time was an aerospace engineer at British Aerospace Space & Communications Ltd. and worked on many European space projects, including HOTOL), for two examples of concept studies for reusable winged orbiters with cryogenic rocket propulsion and subsonic air launch at about 10 kilometers altitude. Both designs had a launch mass of 250 metric tons, which exactly corresponds to the Stratolaunch 'Roc' payload capability. Both studies projected a payload capability of roughly around 7 metric tons to LEO. If anything, I'd suspect that today's numbers would be more favorable, since technology has progressed since both were published.
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Designation Systems / Re: August Euler Aircraft
« Last post by Tuizentfloot on Today at 07:11:31 am »
And here the other Euler types:

Gliders

1. Chanute type gliders (1909). Three built by Euler (an example had been delivered by Voisin).

Monoplanes

1. Eindecker Nr. 1 (August 1911). With 4-wheeled undercarriage (in pairs in tandem). Gnome, 70 HP.

2. Monoplane (first flight 28 September 1912). Single seater with viewing panels in the fuselage. Gnome, 50 HP.

3. Taube-like monoplanes (1913). Three built for the Prussian army. Argus, 95 HP, or Daimler, 85 HP. An original Taube had earlier been delivered by Rumpler to Euler.

4. Typ Nr. 5 (1913). Racing monoplane, ressembling the earlier 1912 monoplane. Adler, 80 HP.

Biplanes

1. Großer Gelber Hund with frontal engine (October 1912). Daimler, 70 HP.

2. Biplane with staggered wings (February 1913). Argus, 100 HP.

3. B I = Doppeldecker Typ 1914 (1914-1915). Licence production of LVG B I (with adaptations). Daimler, 100 HP.

4. Biplane with engine aft (1915). Gnome, 100 HP.

5. Biplanes with engine aft and armed with machine guns in different arrangements (End 1915); Daimler, 160 HP.

6. Cabin biplane with engine ahead and armed with fixed machine gun (January 1916); Daimler, 160 HP.

7. Cabin biplane with engine aft and armed with fixed machine gun (February 1916); Daimler, 120 HP.

8. C I (built in 1916). Daimler, 160 HP.

9. D I (1916-1917). Oberursel, 80-100 HP.

10. D II (1917-1918). Oberursel, 100 HP.

11. D 5 (May 1918). Daimler, 160 HP.

12. D 6 (April 1918). Siemens, 160 HP.

13. D 7 (August 1918). Daimler, 160 HP.

14. D 9 (1918). Daimler, 200 HP.

15. D 10 (July 1918). Daimler, 160 HP.

16. B III (1918). Licence production of LVG B III (with modifications).

Triplanes

1. Dreidecker Nr. 1 (1911). Pusher with Gnome.

2. Dreidecker Nr. 2 (January 1913). Argus, 100 HP (engine ahead).

3. Triplane flying boat (1913). Gnome, 100 HP.

4. Triplane (December 1916). Two seater side-by-side. Daimler, 220 HP.

5. DR 4 (April 1917). Oberursel, 160 HP.

6. DR 5 (April 1917). Daimler, 160 HP.

7. DR 6 (March 1918). Goebel, 160 HP.

8. DR 7 (May 1918). Goebel, 110 HP.

9. DR 9 (1918). Siemens & Halske, 110 HP.

Quadruplane

1. D 4 (April 1918). Gnome, 100 HP.
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I heard that he (Dr Brobet) is the one that designed the mille feuille prior to that...

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Is there any more info? Such as other photos of the model....

No more as I know.
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Aerospace / Re: USAF plans F-15 modernization
« Last post by sferrin on Today at 06:50:32 am »
But that's a component cost, not a raw material cost.

Commercially pure Ti is running around $25 a pound these days.  Aviation-specific alloys could easily be significantly more, especially with the DoD traceability/accountability requirements.  I don't know specific pricing, but $100 per pound doesn't seem impossible.

About a year ago I bought some 0.24" 6AL4V stock for testing.  No certs.  Came to about $46/lb.  It was a relatively low quantity but it was from a remnant shop.
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Space Projects / Re: Stratolaunch
« Last post by martinbayer on Today at 06:50:10 am »
after all, it worked well for a number of experimental rocket planes, including the X-15.

Which of those went into orbit?

None, but for a fully reusable orbiter air launch just might make all the difference between being able to achieve LEO with a meaningful payload or not without the use of any expendable components.

not really.

It comes down to the actual final numbers - that's why I said "might".
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Aerospace / Re: USAF plans F-15 modernization
« Last post by sferrin on Today at 06:36:41 am »
But that's a component cost, not a raw material cost.

Whoops.  Fair enough.  Carbon fiber isn't exactly cheap either though.  (Nor is the core that goes with it.)
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Aerospace / Re: USAF plans F-15 modernization
« Last post by TomS on Today at 06:23:01 am »
But that's a component cost, not a raw material cost.

Commercially pure Ti is running around $25 a pound these days.  Aviation-specific alloys could easily be significantly more, especially with the DoD traceability/accountability requirements.  I don't know specific pricing, but $100 per pound doesn't seem impossible.

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Naval Projects / Re: Small Surface Combatant Task Force concepts
« Last post by TomS on Today at 06:21:00 am »
https://news.usni.org/2019/01/22/navy-squeezing-costs-ffgx-program-requirements-solidify

Embedded in this story is a slide deck showing the combat system requirements for FFG(X).



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