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Discussion:

PULSEJET V/TOL: The British Harrier jumps to mind. What if we can build a very low cost aircraft that is totally immune to particle intake damage, but won't even set a dry field afire? Well, we can. Check out the illustrations and photos. So how do we take a proven, but little known technology, and put it to work?

First, what are the propulsion system weaknesses, and how can we design around them? The two biggest drawbacks to the pulse reactor powerplant are high volume to thrust ratio and loud noise. The answer to the first problem is using three blastwave engines in the following manner: one for forward propulsion with a swiveling augmenter, and two engines that face forward and are only used for vertical lift.

How does this work? First, these engines are really cheap and light. We use double augmenters, with the first sets made of carbon fiber with complex curvatures. The second set will not only deliver extra thrust, but will swivel to provide additional forward lift (or thrust reversing) power as well.

The second problem, noise, is a problem in itself to answer. Because patent work is a bit further down the road, there is not too much to say, except this: we are working to lower exhaust velocity and replace it with air mass in a new and unique manner, and feel confidant we can reduce the noise to quite workable levels.We consider the solution of the inlet problem of the Blastwave pulse-ramjet a real inspiration on the part of Ray Lockwood.

One of our projects is to design and build a futuristic hybrid jump-jet for one or two passengers, which would use two sets of Blastwave shrouded pulse reactors for VTOL use alone, with a separate forward propulsor such as a single Blastwave engine, or Rotax engine with propeller. It would be able to fly in, and land on places (such as a steep mountainside) that not even a helicopter could attempt. Uses would include rescue, ship to shore transport, and civilian recreation and travel, as we should be able to produce this VTOL aircraft at low cost, due to the simplicity of the Blastwave engines. Hovering efficiency is not terribly important to the aforementioned 'jump-jet' application, yet, it's not bad at all. Our other Pulsejet V/TOL design uses a Tipjet driven rotor which substantially increases hover and vertical take-off and landing efficiency. (See AERO-INFO I &II)

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ABOVE: Hiller pulse reactor trailer test rig at Moffet Field, CA. At top speed of 80 mph demonstrated a 25% improvement in thrust. (300 pd thrust package produced 375 pds thrust) and a relative improvement in thrust specific fuel consumption. It was presumed that the increase in thrust was due primarily to less re-circulation of hot gases. If equipped with a Blastwave ram shroud, it is further presumed that this thrust increase will continue into the supersonic regime, but we'll only know for sure when actual testing has been completed. The rare Mercedes 300 SL road race edition car (capable of 170 mph) in background was considered for use as a higher speed tow vehicle until auto enthusiasts found out and raised quite a commotion about modifying the car. I do sympathize, but higher tow speed results would have been interesting. What they needed was a faster truck!

Ray recognized that a major reason a typical ramjet is so inefficient is that the combustion wave just looks for the easy way out, whether it's upstream or downstream. This is why a ramjet is efficient only at high speeds (as speed increases airflow forces the explosive wave toward the outlet). Pulsejets and Ramjets have two things in common: incredible simplicity with no moving parts, and incredibly complex fluid-dynamics. The inlet solution to combining these technologies is using a re-entrant oriface, shaped like the inner curvature of a donut, with a reflector cone, so the explosive waves are focused in a single direction. Think about this. When an explosion occurs, it expands outward, but in this case, all the energy is re-focused to the exhaust of the pulse-ramjet. It's better geometry for a pure ramjet up into the hypersonic range.

Pulse Reactors in Blastwave Shroud Seen As Answer to VTOL Lift Problems: The Hiller-Lockwood pulse reactor engines, acoustically paired in a `Blastwave' pressure-gain ram shroud, promises to overcome the rough-field vulnerability of jet lift VTOL propulsion systems because of its absence of moving parts and the fact that it rejects rather than ingests foreign particles.

Use of a turbojet engine as a direct-lift propulsion system leads to excessively high downwash velocities and temperatures, extreme disturbances of loose material on the landing surface, and possible fire if the terrain cover is composed of brush or dry grass. Screening of inlets is ineffective because of the problem of clogging of the screens.

The pulse reactor, on the other hand, has low jet downwash temperatures, and has the unique characteristic of rejecting foreign particles which are heavier than air. It is competitive with turbojet engines in hovering and low-speed performance, and has a hovering specific fuel consumption of better than 1.0. The only disadvantages of the basic pulse reactor engine are high noise levels, and a rather poor volume-to-thrust ratio, and the Blastwave shroud promises to solve these problems, and provide inherent engine shell cooling thru pumping action which increases air mass-flow while decreasing exhaust gas velocity.

All these systems work by inducing a co-flow stream of air around an engines exhaust gases, creating a virtual air shroud to prevent the creation of excess noise. However, the Blastwave shroud is unique in that it uses an annular re-entrant orifice diffuser and exhaust section, reflector cone, and other reflective surfaces to promote wave compression as well.

It is postulated that the Blastwave shroud could be used to produce a ramjet that is more efficient at supersonic speeds, and fitted with a pair of pulse reactors, it will efficiently produce static thrust, and at sub-sonic speeds (More data will be available after our patent applications are in -force).

IN FORM, the Basic Pulse Reactor engine resembles a horseshoe-shaped empty pipe, fitted at each end with a second pipe serving as an augmenter. The engine is started by injecting fuel, spark, and a brief blast of air simultaneously into a combustion chamber. As combustion occurs, pressure builds up and gases blow out both ends of the combustor or pipe, and the jets move into the thrust augmenters with the effect of a one-way piston. The mechanism of energy transfer from the primary jet to the secondary flow in the augmenter is not fully understood, but Lockwood postulates that a pressure drop on the back side of the gaseous jet piston induces a flow of air in over the lip of the augmenter. The curvature of this flow is associated with a pressure drop which gives a thrust load on the augmenter acting in the same direction as the pressure load on the combustor.

As the pressure rises, fuel flow is automatically cut off. Then combustor gases over-expand, causing a pressure drop which reactivates the fuel flow into the combustion chamber and causes a reversal of air flow back into the inlet and tailpipe of the combustor. Hot gases which did not leave the combustion chamber during the first sequence are swept back and mixed with a fresh charge of fuel and air, causing automatic re-ignition at multiple points. The pulsing cycle is dependent on combustor size, but is approximately 125 cycles per second for a 5.25-in diameter combustion chamber. The engine can utilize almost any type of fuel, and has potential for extremely low production costs.

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Shown Here: A pulsejet, modeled after the original Marconnet invention, is immersed in water, lifted out, and fired up …all within 5 seconds. Try that with a turbojet!

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The Hiller-Lockwood pulse reactor jet engine is unique in that its exhaust temperature is so low that it won't set dry fields afire, and it is totally incapable of intaking solid particles of any sort.

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Above: A clean burning multi-fuel pulse reactor in action. A pair of these engines, equipped with thrust augmenters weighed 30 pounds, and produced 300 pounds of thrust. They are efficient, cheap to build, can use almost any fuel, are completely immune to particle intake damage, have low exhaust temperatures, and can be produced in various shapes as long as the basic geometry is retained.

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Below: Photo illustrates the vulnerability of a turbojet engine to particle intake damage. A single bolt or rock ingested will cause very expensive damage, and even complete failure.

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The world's first pulsating jet atomizing/spray drying system.....invented independently in 1965 and developed under the auspices of Stanley Hiller, Sr., Litton Industries Atherton division and W. R. Grace Co. by Raymond M. Lockwood.

Cycle diagram shows the way these simple jet engines work.

 

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