The Horten XVIII and the YB-49

The Horten XVIII and XVIIIb came up in a "what-if" thread as a potential "Amerika Bomber." I thought that comparing it to an actual quite similar post war aircraft would be instructive of just how myopically euphemistic the Germans got towards the end of the war in casting about for a war winning wonder weapon.

The Horten design called for a 4,000 kg (8,800 lb) bombload on an aircraft with roughly a 150 foot wing span using either 4 to 6 HeS 011 (2,866 lbs thrust) or 8 Jumo 004 (1980 lbs thrust) jet engines for power. The aircraft was to be built largely of wood. Most other details of this aircraft are sketchy at best. It was not constructed and never flew.

Northrop's YB-49 jet engined flying wing bomber did fly however. Its chararcteristics were:
Wingspan of 172 feet. Loaded weight 190,000 lbs. Power was provided by 8 Westinghouse J35-A-15 engines rated at 3,750 lbs thrust or about double that proposed in the Horten design. Service ceiling was 40,700 feet. Range with a 10,000 lb bombload was 1403 miles at 367 knots speed. Maximum speed was 428 knots at 20,800 feet.
Unlike the earlier propeller driven XB 35, the YB 49 was found by test pilots to be "extremely unstable" and " impossible to hold a steady course or constant airspeed or altitude." In tests against the B-29 and B-29D (aka B-50) its performance was considered poor and inferior. The YB-49 proved to have a CEP on bombing runs over double that of the B-29. For this and other reasons, Northrop's design was cancelled.

Basically, there is little credible evidence that even if built that the Horten design would have proved somehow even equal in performance to the US craft. It would have been undoubtedly heavier relying on wooden construction in many areas. The Jumo 004 engines could not have been reliably expected to last a full mission with at least the failure of one or two during flight due to their low life expectancy. The HeS 011 engine was never really tested and did not reach production so we can't know what its actual performance might have been.
With higher specific fuel consumption, the Horten design would never have reached its intended range specification of a bit over 6,000 miles. It is more likely if it had flown that it would have had a performance worse than that of the YB-49. This means that it might have a 1,000 or so mile range and a cruising speed such that even late WW 2 piston engined fighters could have intercepted it.

 

I really like the HO IX, it is still a beautiful plane and truly advanced design for it's day.

 

As much as the YB-49, so why single the Ho out? Because of the sexy paint scheme? Bah!

 

No, I just happen to like that one.

 

The HO IX was a better design than the Northrop and smaller, faster than the HO XVIII.
Just a pretty slick aircraft, if they had more time it could have become the best fighter.

 

This is one of the first powered flying wings. He did not have backers so the plane went no where.
I seem to recall Bellanica designed a flying wing but I can not find a picture for it and I don't recall the name.

A Rocky Road to the Clouds | BusinessWeek

 

Please explain why.

 

Ah well, see here how the Horten and Northrop principles are different.

Horten Nurflugels

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Funnily the Raiders of the Lost Ark Flying Wing was based on one of the Northrop concepts
Raiders of the Lost Ark, Flying Wing Fight Scene • VideoSift: Online Video *Quality Control