delcyros said:
First of all, Horten was on something. In fact he developed the aerodynamic rules of the bell shaped lift distribution to give his designs (following the Ho-III) the margin of stability typically missing on flying wings. Horten designed and build many planes in the post war period for sport aeronautics using his design principles. This is not without tradeoffs in drag but more importantly, he was ignored by Northrop, Handley Page and others for his findings in the 50´s, 60´s and 70´s. This is confirmed by dozens of unanswered letters surviving in the archives, where Dr. R. Horten points to his theories adressed primarely to Northrop.
He was not ignored by Northrop. After the war Walter Horten was actively pursued by Northrop to come and work for him. However, Northrop did not have the political clout (like Horten mentioned in his note) to get him to America. I think this was a tragedy as Northrop and Horten were unquestionably the leaders in the flying wing field. While I do not believe Horton had a lot to add to the work of Northrop, there is no doubt he could have made significant contributions and reduced development effort. I do not think he could have saved the B-49 from the politics of the day. Also, I think that, working with Northrop, he would have gotten recognition that he justly deseved.
It took until the late 70´s that his findings were confirmed by intensive aerodynamic research and his rules are today applied to flying wings of RC-scale, ultra-light design, gliders and single engine powered flying wings, which do not make use of fly by wire technology.
I believe analysis indicate that, while the Horten design of gliders are good, it has drawbacks in the area of drag.
and thus is the rightly preferred solution for large flying wings today.
No, stability is handled by electronics so airfoils are design for optimum performance, not stability. I believe the B-2 has elliptical lift distribution.
Had Northrop, Handley Page, A&W all applied his rules on their fyling wing design -how can You say that these design would have operationally failed based on other criteria than lack of stability (which is properly adressed with bell shaped lift distribution)?
The B-49 did have yaw instability but a Honeywell Electronic Yaw Stabilization System corrected the problem and the B-49 was a "very stable platform", according to "Northrop, an Aeronautical History".
By the end of the war, John Northrop had considerable more experience in powered flying wing designs than the Horten brothers. Here is a list of powered flying wing aircraft flown by May, 1945.
N1M-July, 1940 – low performance twin engine test vehicle
N9M-Dec, 1942 – low performance Twin engine test vehicle for the B-35-still flying
XP-56-Sep, 1943 – High performance Single engine fighter aircraft
MX-324-July, 1944 – High performance, rocket power aircraft, a U.S. first
JB-10-1945 – V1 type cruise missile. While it had a few successful flights, it had unknown development problems.
In addition, the XP-79B flew in Sep, 1945. It could have easily flown in early '45 had it been originally been designed with turbojets instead of a failed rocket engine. This plane was similar to the Ho-229 in that it was a twin turbojet, flying wing fighter. It was smaller, thus less versatile, and not as clean or advanced as the Ho-229, but, due vertical stabilizers, most likely represents a more reasonable configuration. Interestingly, the XP-79B also crashed on its initial test flight when the pilot tried to slow roll the aircraft, something very stupid. Cause of the accident is unknown.
The Horten brothers only had the Ho V-B, low performance twin engine test vehicle, the Ho VII, which appears to have had limited testing, and the Ho IX V2, a high performance twin jet test vehicle (two hours of flight).
Evidence for ignoration of these theories may be found in several cases. All Northtrop design miss the bell shaped lift distribution developed by Horten. Further, I quote from Dr. Horten himselfe, published in Horten / Selinger, Nurflügel. Die Geschichte der Horten Flugzeuge 1933 - 1960 (Graz 1993), p.224:
Certainly not a non-bias account. It would be interesting to have heard Northrop's comments on this.
"Nearly all the new aircraft projects in Germany at the end of the war were tailless designs.
I'm not sure this is true.
I tried to offer my services to the Fairy Aircraft Company in 1947 for work on the supersonic delta aircraft, but while the management was positive in all respects, the general hate-attitude of the people against Germans driven by public press made working there impossible.
Apparently this was somewhat true in America, as I stated before.
Northrop published details of a new aircraft similar to the H V at that time. The machine had negative dihedral wing tips in an apparent (but useless) attempt to combat the skid-roll moment.
According to "Northrop an Aeronautical History", the dihedral worked. The N9M however, had no dihedral and was very stable when flow (video in this site testifies as such).
I tried to contact M. Northrop and offer my assistence, but without success. Later, Northtop factory wasted a large amount of money on several unsuccessful heavy bombers, similar to the H VIII or H XVIII. They could certainly have benefitted from my knowledge of high aspect ratio flying wings! "
Even if Northrop had been able to get Horten to work in the U.S., I don't think he could have saved the B-49 from political extinction. However, if he and Northrop had conspired to build an upgraded Ho-229 with more modern engines and maybe vertical stabilizers, there may have been a serious competition to the Mig-15 and F-86 in the early 50's.
Soren said:
Good post delcyros, I agree completely.
It has actually also been mentioned several times that the technology was forgotten until the development of the B-2 started where staff from Northrop went to the hangar to painstakingly research the Ho-229's airframe in detail. Now why would they have done that if it wasn't for the fact that there was a lot to learn from it??
I suspect this was just a boondoggle for Northrop. Aerodynamic analysis, computer control, and manufacturing technology were many generations past the Ho-229. I don't think there was anything to learn. I only think the center section was available.
Flyboy said:
I have issues with that statement.
The B-35 had some propeller governor issues that were eventually addressed, but the war was well over by then. There was always reports of the later B-49 stability problems that eventually lead to an award to Convair for the B-36. Jack Northrop stated on his deathbed that he had conflicts with the DoD and even Truman himself and that is what ended the Northrop flying wings. The B-35 and B-49 did have some issues that could have been addressed especially if the war progressed. IMO neither aircraft could be considered "unsuccessful." Here's a good paper on this.
I don't think the B-35/49 would be any more difficult than the B-29 to make into a great bomber. Only the effort was different.
Soren said:
Yeah I believe Northrop could've made it work as-well, the needed information was there. They could however still have benefitted a lot from including Horten in the project, esp. in cutting down on research time seeing that Horten already possessed all the knowledge needed.
Probably not all the knowledge since he was not as far along as Northrop in the building of large flying wing aircraft. Flight trials have always enlightened designers.
vikingBerseker said:
I watched a special on the Northrop Co and it did state that it was politics that killed the B-35/49 projects. It did end on a very cool note. Before he passed away, he was shown him a model/mockup of the B-2.
I was at the Northrop facility when he came. I saw him but I could not attend the briefing. I was not cleared for the B-2 at that time. Also, as I was probably not important enough.