Sikorsky S-97 First Flight

There have been several articles regarding the Sikorsky S-97 Raider, which achieved first flight this week. The Sikorsky S-97 Raider prototype takes to the air for the first time

FoxtrotAlpha’s got a good backgrounder on this aircraft, its history and future.

There were some nay sayers in quite a few comments that I hit on a couple of the articles that pooh poohed the coaxial rotor as a limited solution for high speed vertol aircraft.

I think the mistake these folks have is confusing this machine with the older coaxial rotor machines like the Kamov KA-50 below (“Russian Air Force Kamov Ka-50” by Dmitriy Pichugin)

Russian Air Force Kamov Ka-50.jpg

A quick scan of the two pictures, focusing on the rotor mast and then the blades, will show you that there are a lot of differences in the aerodynamics.

Helicopters are speed limited because the blades are moving in respect to the air passing the aircraft. On one side the advancing blade adds to the air speed and at the tip can easily move towards the supersonic where air becomes in-compressible and aerodynamics change radically (which is why the blade tips on high performance helicopter blades are swept like a fighter wing) On the retreating side the blade can quickly reach stall speed and loose lift..

Coaxial rotors have the advantage of putting more energy into the air in a smaller rotor disc. Because the length of the rotor blade has a large impact on the tip speed this reduction means that the aircraft can fly faster before hitting the above limits.  Also since one blade on each side is advancing and the other retreating lift is symmetrical even if the retreating blade looses lift, meaning the aircraft can fly faster.  And indeed the X-2 demo aircraft Sikorsky built as a tech demo before the S-97 hit something like 300 miles per hour while a conventional chopper maxes out at about 150.

The principal difference between the KA50 and S-97 is the type of blade control. The S-97 has a so called rigid blade, which does not have a flapping hinge at the rotor head. The hinge is part of the  conventional blade control system allowing the blades to flutter somewhat as the lift changes through the blades rotation (you can see in the picture of the KA50 that the blades are at various incidences to the path of flight, partly because of the turn but also because of this ‘flapping.’)  The more advanced though simpler and more rugged rigid blade system on the S97 is based on advance composites and aerodynamic control theory.

So why does it matter, why do we need faster helicopters?

Simply put speed up to a certain point is always a winner because it means that for the same cargo load you can move more material in a shorter period of time. It also means you spend less time in any particular point in space which in a military context means you’re less of a target. Fast and being able to land anywhere and hover behind cover are all very interesting to the military.

Harrier jump jets

The other fast vertical take off aircraft, the jump jets like the F35 and the Harrier or the tilt rotor V22 Osbrey are really optimized for vertical take off and landing and fast transit, the jump jets have no real hover capability and the Osprey is a big and somewhat clumsy helicopter. The S97 is much more of a blended capability and its simpler and cheaper than a jump jet or tilt rotor. Sikorsky is hoping that they can convince the DoD to forgo doing too much specmaniship and competitive development and move forward with the coaxial rotor machine for the next generation of vertical lift air mobility platforms.

Of course right now the outlook for anything new is pretty bleak and Sikorsky is probably struggling to figure out where to take the technology they have developed. A typical ‘innovators dilemma the world of modern military acquisition.

From AW&ST Things With Wings


If you have heard of Richard Lugg, you probably know him as the man behind the HyperMach SonicStar supersonic business jet concept. And as if Mach 4 cruise, supersonic laminar flow, plasma drag and boom reduction, and superconducting electric propulsion were not enough, Lugg’s name appears on a new US patent (8,636,241, filed in 2006) for a hybrid jet/electric VTOL aircraft.

My feel is you don’t need SciFi tech to get on this road.

The hybrid jet/electric VTOL design looks a bit more practical and, if not Lugg’s design, then some similar form of distributed-thrust, electric-propulsion VTOL is going to fly sooner rather than later, I am sure.

Stupid…back at the beginning and today

20130827-065512.jpg 20130827-065540.jpgFrom The USAF Stands Like A Rock

August 26, 2013: The U.S. Air Force continues to come up short in its effort to supply enough pilots for its growing UAV fleet. Currently the air force has about 1,300 operators for its 280 large UAVs (about half of them Predators, nearly 40 percent Reapers and the rest Global Hawks). UAV operators are now nearly nine percent of all air force pilots, triple the percentage in 2008. But now the air force is unable to get enough manned aircraft pilots to volunteer to do a three year tour as a UAV operator and cannot train non-pilots fast enough to be career UAV operators. Another problem is dissatisfaction with the job. UAV operators leave the air force at three times the rate of pilots of manned aircraft. There are several reasons for this. UAV operators have a heaver workload than pilots of manned aircraft and less time to study and prepare for promotion opportunities. As a result UAV operators are promoted at a rate 13 percent lower than pilots of manned aircraft. Worst of all, UAV operators are not shown the same respect as pilots who go into the air aboard their aircraft. All this would go away if the air force allowed NCOs (sergeants) to be operators of the larger UAVs but the air force leadership is very hostile to that idea.

Absolutely certain that the AirForce and Navy can come up with highly articulate rationales for their systems but it’s all politics and tradition. In the end stupid since it damages the very ‘institutions’ the ‘traditionalists’ think they are protecting.

Sometimes old & reliable is far better than new and shiney

20130823-202452.jpgAt: Stick With The Tomahawk, Forget LRASM
on July 12, 2013
By Steve Russell

In America’s culture of optimism and innovation, there is always the desire for the better mouse trap. Sometimes, traps are needed to catch rats and not mice, so the mouse traps must be replaced. Sometimes, the existing traps can be modified to more than do the job against the actual threat they face. But we must be intellectually honest and ask, “Can what we have already get it done?”
For example, the .50 caliber Machine Gun was designed in 1919. That’s right, just after the First World War. It has been successfully upgraded and is still used today by all the armed services. It is efficient, deadly and respected by all of us who have used it in battle to defeat America’s enemies. Why? It simply works. America has protected thousands of lives and saved billions of dollars by resisting the calls for a potentially better mouse trap.

Too many times the urge to build new vs. incremental upgrade is hard to resist especially if a clique of advisors is captured by an aggressive sell of shinny new technology. ( Though alternately it can be hard to tell when an old war horse needs to be put out to pasture.)

But…if the shinny new blivet is only incrementally better and many or all of its advantages can be spun onto the old gray tiger you really have to consider incrementalism.

Speed, stealth or smaller, are often sold as the key advantage of a new frame…but most of the time the advantage so bought costs in $’s and in lost capability, flexibility, or maybe even reluctance to pull the trigger given a fear that the shinny new tech will be revealed to the oppo…

Especially in a world of rapid change the urge for the new is not necessarily a good one. Too many times a brilliant idea today is obsolescent before it’s out of development and can get caught in a horrifically expensive dollar death spiral chasing evolving requirements.

Also remember that the old guard primes have huge infrastructures (and stockholders) they have to support. And upgrading old systems will not fill the pipeline. So they have a strong motivation to denigrate the old and laud the new, so do many in the DoD bureaucracy.

Unfortunately for the new platforms, most technologies coming down the affordability curve are as good for, or better at upgrading older platforms or capabilities, than providing big step changes at the platform level.

Not to say that this won’t doom some old war horses. I’m not confident that the CVN is anything more than an admiral’s yacht and diplomat’s crutch these days.

Dream Chaser you have to like the name


Dream Chaser in a captive carry flight over the Mojave. (Credit: Sierra Nevada Corporation

EDWARDS, Calif. (NASA PR) – NASA partner Sierra Nevada Corporation (SNC) of Louisville, Colo., successfully completed a captive-carry test of the Dream Chaser spacecraft Thursday, Aug. 22, at the agency’s Dryden Flight Research Center in Edwards, Calif.

Puny Titan, giant idea, solar powered pseudo satellite


Artist’s rendering of Solara 50 at high altitude.
Titan Aerospace


The coverage area of a Solara 50, superimposed over New York.

From ars technica:

Almost orbital
Titan’s aircraft plans are … modest and … ambitious at the same time. Solara 50 will have a payload of just 70 pounds—though depending on the time of year and location of the flight, longer daylight hours could sustain flights with heavier payloads. The next design, the Solara 60, will carry up to 250 pounds. Instead of using hydrogen fuel cells, the Solara aircraft use batteries charged from solar panels to power flight at night and provide about 100 watts of power to the aircraft’s payload, as well.

The Solara 50 has a 50 m (164 feet) wingspan. The upper surfaces of its wings and tail are packed with over 3,000 photovoltaic cells capable of generating up to 7 kilowatts. It is launched by catapult and can land (when it has to) by skidding on its Kevlar-coated underside. Unlike the giant flying-wing configurations of the Helios and Zephyr, which had large numbers of propellers, the Solara has a single, high-efficiency motor.

In theory, a solar-powered drone capable of withstanding long flights at high altitude—in what Titan executives call the “sweet spot” in the Earth’s atmosphere between 60,000 and 70,000 feet, above nearly all weather patterns in a zone where winds are typically less than 5 knots (5.75 miles/hour)—would be able to perform tasks usually reserved for satellites at a much lower cost.

Several orders on the books, reasonable objectives, good idea, what’s not to like?

Someone got carried away with their QuadRotor project! Gas Electric Propulsion and battle gray!

AWST Ares Blog: New Ways To Fly by Bill Sweetman

New at AUVSI was a variation on the quadcopter from Latitude Engineering of Tucson – the hybrid quadrotor, or possibly octorotor. A piston engine drives a generator, turning four electrically powered rotors (on the prototype). The next generation vehicle, weighing 60 lb, will have eight lift rotors installed in pairs, above and below the booms. Latitude says that three of the latter vehicles have been ordered by Naval Air Systems Command for a test program.