Valveless PulseJets .

Valveless PulseJets .
Andre Willers
2 Jun 2010

Synopsis:
A cheap and easy pulsejet engine that operates at low speeds .

Discussion :

References :
Actual working engines : see PopularMechanics.com , May 2010 , p79 .

See also http://andreswhy.blogspot.com "Tornadoes and V1" 15 Mar 2010

Google "Hilsch tubes" , "valveless pulsejets" , "Madagascar Institute NY"

Safety :
This is old technology , dating back to 1938 .

How it works:
The valveless pulsejet is at heart a classical T-shaped Hilsch tube , but the stem of the T is replaced by the combustion chamber . This provides the pressurized gas-input .

The Tricks :
1.The exhaust is bent in a U shape . This is where the Hilsch effect appears . Part of the pulse-effect appears here .
2.After the U bend , the exhaust flares . This regulates back-pressure and the pulse effect .

Low speed .
The Hilsch-effect makes the process much more efficient than the old V1 motor .
Much lower speeds are required for the motor to operate .
Hence the tornado-effect .

Manufacturing costs :
Can be made out of a U-shaped car-exhaust , a cylinder of gas for fuel and a modest compressor (eg leaf-blower) to kick-start it .

Enhancements:
The system can be significantly enhanced by incorporating the spiral-shaped Hilsch washer into the bend of the U-shape .

The vortices inside the tube can be tricky . Use a powerful computer for optimization calculations . This was not available in the past , hence the falling into abeyance of this technology .

Ram-jets .
These are back in fashion for hypersonic jets . Their main drawback is the high speed necessary before the ramjet becomes self-supporting .

Pulsejets are low-speed ramjets .
The most elegant solution would simply be to switch the ramjet's intake scoop into the pulsejet's combustion chamber once ramjet threshold speed has been slightly exceeded . This modifies the low-speed pulsejet into a hypersonic ramjet and vice versa .

Historical note :
Possible Past and , hopefully , not possible future .
This classically simple and elegant technology could have been manufactured soon after the metallurgy for high-speed turbines became possible : Ie 1890's .

This would have resulted in a completely different historical pathway .

Even as late as 1938 (Std Timeline) , low-speed pulsejets would have radically altered the European and Pacific theatres . Notice the effect of the V1 .

Combine with hovercraft , and large war hover-platforms (millions of tons) , populated initially by regiments , but later tribes careen over the plains of Northern Europe and Oceans of Terra at hundreds of kilometers per hour . (Note that pulsejets can run on bio-manufactured gas like methane ,etc . The platforms can be fuel-selfsufficient.) .

A return to the days of Attila and Genghis . The Knights-and-Castles defence would require nuclear weapons to maintain itself .

Note James Blish "Cities in Flight" , but these platform-cities would be on a planetary surface . The constraints should give a lively time to all .
Their only vulnerability would be from orbit . A lively armed discussion about sovereignity and free-passage should ensue .

The surviving platforms would be forced to become launching platforms , culminating in Orion-type space platforms . The planet would be a wreck .
See http://andreswhy.blogspot.com "Orion , Gaia needs you" et al .

To paraphrase Tolkien :

"One tube to bind them all ."

Andre