Three MR bladed Bell 204

[John Eacott]

The things you see on t'internet thingy: a 204 with three main rotor blades

Needless to say, absolutely nothing about what, why or where but with the wisdom contributing here: does anyone know WTHIH?

[vfr440]

204B

FAA registration gives this as 204B, S/N 1501, built 1963, but registered Feb 5th, 1970 to Bell in Ft Worth; cancelled Dec 4th, 1980. Reason - 'Destroyed'. So I don't think that sheds much light on the situation.


Perhaps a collaboration with Agusta? Didn't they have a version (not very satisfactory) with a Gnome engine for Europe?


Intriguing - VFR

[Thridle Op Des]

There is a quote at Bell 533 helicopter - development history, photos, technical data

"Still with its original US Army serial number, the Model 533 made its maiden flight on Friday 10 August, 1962, and flight tests were conducted at Fort Worth in late 1962. In March 1963, the Model 533 flew at 278km/h and 302km/h was attained in a shallow dive. As the months went by more and more modifications were introduced in this helicopter. Several rotor types were tested (two-blade UH-1B-like rotor and rigid three-blade rotors) and two 765-kg Continental J69-T-9 turbojets were installed on each side of the fuselage. Take-off weight of the aircraft was now 3880kg. On 17 January, 1964, the helicopter achieved a speed of 338km/h in level flight using only 780shp from the 1.100shp Lycoming T53-L-9A shaft-turbine, plus 568kg from the J69s."

TOD

[Ian Corrigible]

C/o Stingray:





Details on the two-bladed trials are available at the U.S. Army Aviation Digest Archive. Warning, large (72MB) file!

I/C

[terminus mos]

TOD, reminds me a little of the day the skid mounted 214ST came to Redhill resplendent in its beige and orange paint scheme with bar graph power train instruments.

[tottigol]

Well, that would have been an interesting development...had it been undertaken by any other manufacturer not resistant to legal progress.

[NickLappos]

That airframe sits on a pad in front of the US Army Aviation Engineering facility (Aviation Applied Technology Directorate - AATD) in Ft. Eustis, Virginia (37.166921 N,-76.60188 W on Google Earth!) It was built and flown by Bell Xworx engineering, and by US Army test pilots, and set an unofficial speed record back then. The wings and thrust offset the rotor, which was loafing along for the ride at high speed. Its final high speed was 275 knots in level flight, about 15 knots faster that EC/Airbus (really?) X3 and 20 knots faster than Sikorsky X2, and 60 knots faster than the Lynx official FAI record that still stands.

The highest speed trial was flown by Lou Hartwig, Bell Experimental pilot and Duane Simon, chief Army test pilot and great guy. Duane told me that at 250+ knots, the 2 per rev vertical vibration was eye-watering, but worth it. The whole story is posted in the bottom comments on:

Bell 533 helicopter - development history, photos, technical data

Duane Simon described an emergency landing here:
http://articles.dailypress.com/1994-...pter-work-aatd

Making the 533 three-bladed would use a gymbol head, where the teetering rotor would still be used, with a hub ring that attaches the blades, and that teeters to keep the mast happy. That teetering head would have been similar to the V-22 rotor head, which is teetering, also, for the same reason - keep control moments low and keep mast/transmission light weight.

[John Eacott]

Following on from Nick's account of the compound version of the 533, I saw this photo recently. Intriguing design on the extra horizontal stabs!