Jan 082019
 

Bell has unveiled their idea of what an electric intra-city VTOL “taxi” would be, in the form of the “Nexus” AirTaxi. one wonders if it’s more human than human?

Bell reveals the ‘Nexus’ VTOL

On one hand, it bears more than a passing resemblance to the Bell X-22. On the other hand, there are some design choices there that make me scratch my head. The thrust from forward ducts would be bisected by the main wings at forward thrust and then blast right into the rear fans. During transition, the forward thrust would be disrupted by the main wings, which would seem to lead to some fantastic turbulence.

 

 Posted by at 9:30 pm
Dec 292018
 

Sikorsky is currently flying the S-97 “Raider” helicopter featuring the ABC (Advancing Blade Concept) rotor. ABC rotors look like conventional coaxial rotors, but differ in being structurally stiff and inflexible. The idea is that ABC rotors allow faster flight: in a conventional single-rotor helicopter, the faster airflow means that on one side of the rotor disk, the “advancing blade” slams into the air at a very high speed, potentially generating a lot of lift. But on the other side of the disk, the “trailing rotor,”  which is moving aft at a speed not far off from the airflow, generates very little lift. This of course imbalances the aircraft and limits forward speed. The ABC system, by having coaxial rotors, make sure that there is always balanced lift. The S-97 is not the first helicopter that Sikorsky has built with ABC rotors; the S-69 flew in the 1970s, reaching a top speed of 260 knots. But it suffered from serious vibration issues and did not lead to a production aircraft. The S-97 seems to have fixed most of the issues, and it is hoped that a production contract may eventually come.

The ABC concept dates back *at* *least* 52 years. Below is an illustration from 1966. Interestingly this design more closely resembles – at least superficially – the S-97 than the S-67. The S-69 used two turbofan engines to provide forward thrust, while the S-97 used, like this illustration, a pusher propeller.

 

 Posted by at 6:11 pm
Dec 242018
 

2018-12 Rewards are now available for downloading for APR Historical Documents subscribers. This month the rewards include:

1: A large document: “Sea Launch and Recovery of Very Large Rocket Vehicles,” a 1962 Aerojet report on the sea Dragon concept

2: “Ryan Aeronautical Company Plane Portraits,” information, photos and three-views of a sizable range of Ryan aircraft, manned and unmanned

3: “Nova,” a blueprint of the NASA “Saturn C-8” launch vehicle with 8 F-1 engines

4: CAD diagrams: Star Raker scrap views

If you are interested in signing up, you can do so either at Patreon or directly through PayPal. Signing up now makes you eligible for rewards starting with the *next* months rewards. The directly-through-PayPal system is new; it would probably be best to sign up after the first of the month.

 Posted by at 7:12 pm
Oct 062018
 

A photo found for sale on ebay a while back shows a display model (circa 1973) of a Rockwell International concept for a Grumman Gulfstream 2 corporate jet modified for VTOL capability. This was not meant to be an operational concept, but a research vehicle to demonstrate VTOL technologies and operations in a jetliner-like aircraft, with the potential to be implemented into larger  passenger-carrying jetliners such as the DC-9. This would allow such airliners to operate from smaller airfields. But the fuel-hungry nature of VTOL aircraft put an end to such notions in the 1970s. This aircraft would have used lift fans in flattened pods on the wings (each pod containing two YJ97 GE-100 gas generating turbojets) and vectorable-nozzle forward-thrust fans (again with two gas generators), for a total of six jet engines.

 Posted by at 12:29 pm
Oct 022018
 

Patrons of the Aerospace Projects Review Patreon received last month:

Diagram: A foldout diagram of an Apollo-derived logistics spacecraft

Document: “The Piasecki Story,” an illustrated history of the company and its products

Document: “The N.S. Savannah,” a brochure about the sole nuclear powered merchant vessel

Document: “Lunar Spacecraft Design” A paper describing the evolution of the General Electric Apollo design, quite similar to the later Soyuz spacecraft

CAD diagram: 1985 design of the British HOTOL spaceplane

If this sort of thing is of interest, please consider signing up for the APR Patreon.

patreon-200

 Posted by at 12:39 pm
Sep 252018
 

An ad for Thompson Products from 1958. The cargo rocket shown here is pure artistic license, with almost certainly no actual engineering behind it. It’s pure science fiction for the purpose of advertising razzmatazz. And yet… the similarity to the latest design of the SpaceX BFS is pretty remarkable.

“Thompson Products” may not be immediately familiar. But in October 1958 (about two months before this ad was published in Av Week, so… shrug) Thompson Products merged with the Ramo-Wooldridge Corporation, forming Thompson Ramo Wooldridge Inc. … TRW. So… huh, how about that.

 

 Posted by at 11:55 pm
Sep 082018
 

In the mid-80’s, the Army wanted a light, fast, stealthy and armed helicopter for battlefield recon and the like. It was not meant to be  an attack chopped like the AH-64, but rather something much more akin to the OH-58 Kiowa… it would spot the targets and target them, with the missiles like as not coming in from another source. In the end the LHX program resulted in the RAH-66 Comanche… which, as per usual, was cancelled after only a few were built.

While the Comanche was a more or less coventional sort of helicopter, early in the program the requirements were both aggressive enough and vague enough that very unconventional aircraft types were considered. Single-seat NOTAR and tiltrotor concepts were some of the least unconventional of the unconventionals, and those types got a fair amount of press at the time. It’s difficult to be certain just how serious some of them were, though companies like Bell put some considerable effort into tiltrotor ideas.

One image that I saw fairly commonly at the time was in an ad for turbine engine manufacturer Garrett. It’s a wonderful bit of art for engineering types like myself, and I always hoped that it was a serious design… but it was almost certainly not. Rather, it was either art-department guesswork or, at best, a notional design put forward by an engine company to show to aircraft manufacturers what their engines could do. It shows a single-seat design (the Comanche ended up being a two-seater, because flying a helicopter is difficult enough without the added burden of futzing around with sensors and weapons) with Kamov-style counter rotating rotors, stub wings and numerous air-to-air missiles. The Soviet Hind helicopter was giving NATO conniptions at the time, and an important role for the LHX was to sweep those flying battlewagons from the sky. The design is also shown as having a tilt-rotor option… something that would be truly unique in the history of aviation design. The tail of the craft (if any – it might have been meant to be a really, really stubby aircraft) is not shown, probably because it was never designed. I’d love to be wrong, though… teenage-me loved this thing back in the day.

 Posted by at 9:08 pm
Sep 052018
 

A 1969 Bell  Helicopter design for a high speed stowed-rotor tiltrotor. This was meant for USAF search and rescue and featured gun turrets fore and aft (each with a Minigun) and four turboshaft engines under the wings. Doubtless the gearing from the engines up through the pylons and along the wings to the nacelles would have been an engineering nightmare. But if it worked, it would have resulted in a tiltrotor with the hover performance of the V-22 and a cruise speed of 400 knots.

An article on the similar D270-900-112 (the main visual difference being that the engines were separately podded) was included in US VTOL Projects #1.

I have made the much-larger full-rez scan of the cutaway available to $10+ APR Patreon patrons. If this sort of thing is of interest, please consider signing up for the APR Patreon.

patreon-200

 Posted by at 3:19 pm
Sep 022018
 

From ebay a while back, a B&W PR image of a Sikorsky Skycrane operating as a commercial passenger transport. Sikorsky wanted this to happen in the 60’s, and several attempts to do just this were tried, but it just didn’t really come together. Inter- and Intra-urban commercial passenger helicopters operating as a flying “bus,” often to take people from city centers to nearby airports, were tried but due to cost, noise and safety issues, it never… ah, took off. In contrast, smaller helicopters have done a fair business flying rich folks (and injured folks) round cities, but larger helicopters like this are a thing of the distant past.

 Posted by at 2:24 pm
Aug 182018
 

Another ebay find depicting the Boeing Heavy Lift Helicopter, this time carrying a heavy truck of some kind. Perhaps as a bit of a dig at Sikorsky, in the background another HLH is shown carrying a CH-54 Skycrane.

 Posted by at 11:27 pm