Ammonia is stored as a liquid under pressure (10 bar) in puncture-resistant aluminum tanks lined with a layer of UHMWPE. The ammonia is then sent to the cracker heated by combusting a small amount of hydrogen. This hydrogen is combusted directly inside a module consisting of the reactor surrounded by high temperature vacuum panel insulation manufactured by Nanopore™ in New Mexico. The use of low thermal conductivity insulation allows for minimal heat loss, maximing reactor efficiency. Very low nitrogen oxide emissions are generated from the combustion due to the relatively low flame temperature required, the gas is passed to a micro three-way catalytic converter since the combustion is stoichiometric. NOx emissions are near zero. Air is supplied to the combustor via a small electrically driven rotary compressor, similar to a turbocharger. The cracker operates at 600-650 C, leaving 5-500 ppm of residual ammonia depending on the exact operating temperature, GHSV, and operating pressure. The catalyst used is a commercially available cesium promoted ruthenium on alumina micro powder catalyst marketed as HYPERMEC™ 10010 and manufactured by Acta S.P.A in Italy. The reactor utilizes proven microstructured technology manufactured by Fraunhofer ICT-IMM in Germany. The stability of the catalyst is over 99% over 900 hours.
The high-temperature gas exiting the reactor consisting of 75% hydrogen and 25% nitrogen by volume is sent to a liquid-cooled heat exchanger, similar to an EGR cooler on a diesel engine. The temperature is reduced to 80 C. At this point, the cool gas is sent to an acid impregnated carbon-based absorbent (Calgon Carbon Ammonasorb™) to purify to below 10 ppb. At this point, only nitrogen remains, which is reduced to less than 1% concentration using a polymeric membrane separator. Preferably, the polymeric membrane separation occurs prior to the ammonia purification, reducing the volume of the gas inside the purifier module. The polymeric membrane is mature technology, currently widely used for nitrogen production. Manufactueres include Ube and AIRRANE. The now highly purified cool gas stream can enter the proton exchange membrane fuel cell, generating electricity at an efficiency of 59%. 25% of the hydrogen is required to provide the heat to reform the ammonia, the resultant net system efficiency is 45%. The entire system operates at 3.5 bar, this pressure is chosen to provide sufficient pressure to operate the nitrogen membrane separator, which is designed for pressures of 7 bar, the very high sensitivities of N2/H2 allow for easy separation. A lower pressure is favored in the decomposition reactor, thus a pressure below that ideal for gas separation is chosen as a compromise. Since ammonia is caustic and poses major health risks if released in high concentrations, the tanks are puncture-resistant, which depending on the liner thickness, can prevent a .50 caliber bullet from penetrating from a 15-meter distance. The puncture-resistance comes from the high molecular weight polyethylene liner. The power system has a wide range of applications, ranging from small generators to large scale heavy-duty propulsion.
Pochari Systems is designing, manufacturing and commercializing the world’s first highly compact ammonia cracker to produce hydrogen on demand from liquid ammonia for hydrogen internal combustion engine vehicles or fuel cells.
The cracker uses 4% wt Ruthenium and 20% wt Cesium promoted aluminum oxide supported catalysts in a microchannel configuration.
cracker specifications are based on Engelbrecht and Chiuta 2018,
Chiuta and Everson 2015 and 2016, Di Carlo and Vecchione 2014, and
Hill and Murciano 2014. The activation energy is as low as 49
kJ/mol of NH3 with high cesium promoter loadings on CNT support,
which translates into only 5 KW of heat energy per kg of H2 reformed
per hour, allowing for over 100% of the required energy for
decomposition being provided by exhaust heat from the engine. The
amount of ruthenium and cesium needed is very minimal, only 1 gram 5
grams respectively is required to reform 1 kg of hydrogen per hour at
the desired efficiency and power density.
is critical in the cracking process as it allowes high conversion of
ammonia at lower exhaust temperatures, minimzing unburned ammonia
reserves are estimated to be 84,000 tons, with Ruthenium reserves
11,300 tons, since 5x more cesium is used than Ruthenium, the
reserves allow for the production of billions of medium-sized car
half of the cost of the cracker is found in manufacturing, with the
balance comprising raw materials. Forming
the microchannels from a solid metal block is performed by wire
electrical discharge machining.
and packing of the catalyst inside these tiny grooves completes the
manufacturing process of a microreactor. Microreactor technology can
be thought of as relatively simple compared to battery manufacturing
as an example. The only complexities and difficulties arise from the
very small dimensions These
small dimensions found in microreactors (as little as 0.15 mm x 0.25
mm) requires elaborate and costly machinery to fabricate, but
nonetheless, the cost of the cracker will be approximately $1000-2000
per kg-hour of capacity at high production volumes, of which 50%
represents material costs at current raw material market prices. The
ammonia cracker is located on the exhaust manifold for hydrogen
combustion engines, utilizing engine exhaust heat supplying 100% of
cracker energy needs, with hydrogen combustion providing the
volume of the ammonia cracker for 12 kg/hr, sufficient for the
average fuel flow used by a class-8 semi-truck fully loaded at
highway speed, takes up only 6 liters, and weighs less than 10
cracker is configured in a modular fashion. The modules consist of a
housing, each consisting of a stack of microchannel plates. The
module is placed directly outside of each exhaust outlet on the
cylinder head, allowing the very hot exhaust gas to pass directly
into the microchannels before cooling down. This allows heating the
catalyst bed to provide the necessary activation energy. Each module
is connect to four rails, supplying both gaseous ammonia to the
cracker, and passing reform gas to the purifier. The two smaller
rails provide air and hydrogen to provide heat during startup.
Ru, 20% Wt Cs promoted on CNT
catalyst mass per kg hour H2 reformed: 25 grams
Catalyst required per Kg hour H2 reformed: 1 grams
Catalyst promoter per Kg hour H2 reformed: 5 grams
density: 0.50 kg/kg H2-hr
density: 0.5 L/kg H2-hr
consumption: 5.5-6 kw/kg H2-hr
of reforming energy from exhaust heat: 100%
hydrogen consumed for dissociation: 0% of fuel flow
21st century demands an updated and improved aviation propulsion
technology. For over 70 years, kerosene has proven itself safe,
reliable, efficient, and most importantly, energy-dense.
being abundant, easy to store, and easily combusted in gas turbines,
have resulted in the tremendous aviation industry we have today.
hydrocarbon aircraft can suffice, providing sufficient payload and
range for most missions, only in special occasions is more capability
required. Pochari Hydrogen believes the long-range light business jet
is an aircraft category that requires a more powerful and modern
are rapidly approaching a turning point in aviation history. Efforts
to improve aviation propulsion are reaching a wall. Efforts to
squeeze every last few percentages points of efficiency in turbines
are proving increasingly difficult. The gas turbine’s maximum
practically attainable efficiency is around 40%, going above this
number is nearly impossible. Efforts to improve aerodynamics have
also reached the point of diminishing returns. Reducing airframe
weight through the use of composites, mainly carbon fiber, has
yielded very minimal reductions in airframe mass, in the order of
5-10%. Thus so far we can state that aviation propulsion and airframe
design has reached its peak in terms of technological maturity, there
is almost nothing left to do to improve aircraft capability, at least
nothing currently considered in the aviation industry.
summary, we have reached the point of diminishing returns.
little to nothing remains to improve in the powerplant, airframe
aerodynamics, or even the fundamentally design itself, we must begin
identifying a superior fuel.
surprisingly, there remains a mysterious, obscure, and powerful
propellent, the most powerful of any fuel known to man, that attracts
little to no attention in aviation circles, this fuel is nothing
other than liquid hydrogen as proposed by G. Daniel Brewer in the
late 1970s in Burbank, California, and revived by Christophe Pochari
hydrogen is the most powerful fuel available on earth, with
gravimetric energy density unmatched by any other fuel, hydrogen’s
only downside compared to hydrocarbon is its low volumetric density,
but this proves not to be the least bit of a limitation for subsonic
flight. For subsonic flight at high altitude, the dominant form of
drag is skin friction, a 20-foot diameter airliner fuselage section
(Boeing 787) with a total wetted area of 9500 square feet is only
subjected to 4400 lbf of drag with an air density of 3.5 Psi and a
cruise speed of 560 mph. (http://www.lissys.demon.co.uk). This small
amount of drag present in subsonic flight allows us to store ample
quantities of hydrogen while adding minimal drag, provided we choose
a configuration with the lowest possible surface/volume ratio.
turbine powerplant itself remains nearly identical, having only
slightly modified combustors designed to take advantage of hydrogen’s
much higher flame speed. “Hydrogen is a beautiful fuel for
turbines” -Willis Hawkins.
or liquid hydrogen is delivered from the LH2 tank to the turbine with
aluminum piping from dual high-speed centrifugal liquid hydrogen
pumps directly attached to the rear of the tank. The boil-off rate in
cruise is nearly half of the cruise fuel flow, the difference is
provided by vaporizing liquid hydrogen in the fuel supply line or
combusting it liquid.
electric heater maintains a certain vaporization rate to maintain 20
psi in the tank on the ground, and 15 psi during cruise, if the
pressure exceeds this, the tank is vented.
hydrogen can also be combusted directly in the turbine just as
gaseous hydrogen can. During takeoff, when the fuel flow required is
at a much higher rate than the natural boil-off, the electric heater
is turned up to increase the vaporization rate to maintain pressure,
shortly after, when fuel flow is reduced to cruise level, the heat is
turned down. Turbine compressor bleed air is cooled by the -423
degree LH2, through a light-weight aluminum heat exchanger. Thisallow
for higher turbine inlet temperature, and reduced compressor bleed
air mass flow, reducing compressor work require, this contributes to
a 5% reduction in SFC (Brewer, G. D, 1991)
total ratio of SFC is reduced by 2.93x over the 2.8x difference from
the calorific value difference alone. (Brewer, G. D, 1991)
liquid tanks are integral with the fuselage. The fuselage material is
made of carbon fiber, the tank material is aluminum-lithium, fastened
directly to the carbon fiber fuselage with adhesive. 12.7mm of
insulation is placed between the carbon fiber skin and aluminum tank
wall. Foam insulation is blown inside the frame and between the
frame-wall seams where the vacuum panels end. Tank boil-off is 5% per
hour on the ground. A specially designed fuel truck connects a
flexible hose to the tank when the aircraft is on the ground to vent
the boil-off, keeping tank pressure at 21 psi. Hydrogen aircraft are
fueled just before take-off, to minimize losses.
higher energy density of hydrogen allows for a dramatic increase in
aircraft range, exactly what business aircraft need. With our
hydrogen propulsion system, a 35,000 lb GW aircraft can fly up to
9000 miles non-stop with a 2700 lb payload, whereas the comparable
class kerosene-fueled aircraft can only fly 4700 miles, if it were to
attempt to fly the equivalent kerosene-fueled aircraft, the fuel load
would exceed the useful load by 160%.
Hawkins (C-130 designer) and a strong proponent of hydrogen aircraft,
argued nearly a doubling of range is easily achieved with liquid
hydrogen propulsion, this turns out to be exactly correct.
are two fundamental ways to design a hydrogen-powered aircraft,
depending on the incentives and aircraft capability required.
first way is to essential reconfigure existing aircraft types to
hydrogen propulsion, by incorporating an in-fuselage tank. This can
be done by simply stretching the fuselage, without needing a design
an entirely new clean-sheet aircraft. This design may not necessary
increase range or payload, since the tank capacity may be limited by
the fuselage volume. This type of hydrogen aircraft design would fly
approximately the same distance and carry the same payload as
kerosene aircraft. The rational to develop this type of hydrogen
aircraft would mainly be emission and environmental impact reduction.
The only emission from hydrogen combustion in properly designed gas
turbine engines is minimal nitrogen oxides, less than 50 ppm. No CO2,
CO, PM or any other emission is produced.
The second way to design a hydrogen aircraft is to tailor the design around hydrogen’s improved range capability. This is the option that makes the most sense, as it takes advantage of hydrogen’s superiority as a propellent, allowing the designer to create an aircraft specifically tailored to utilize hydrogen’s enormous performance benefits. Our design is what we term a “flying rocket” which refers to the hydrogen tanking up 85% of the of the aircraft’s volume. This aircraft dubbed the “flying rocket” is a light-jet, under 35,000 lbs gross weight, designed to fly almost 9000 miles (17 hours of flight time) non-stop while carrying a 2500 lb payload, which translates into 6 persons, two pilots, and ample luggage capacity. This ultra-long-range in a relatively small aircraft can only be accomplished with hydrogen, no hydrocarbon fuel possesses the gravimetric energy density. Hydrogen’s outstanding properties as a propellent allow for the creation of an entirely new class of aircraft, that is the small ultra-long-range jet, previously impossible with hydrocarbon fuel.
is a far superior, for more powerful propellant for all aircraft
alike, but it improves the capability of smaller aircraft even more.
Since lift to drag ratios decrease with size, and specific fuel
consumption increases, smaller aircraft gain more from high energy
density of the fuel, these two factors have the most influence on how
much an aircraft improves with hydrogen. As G. D Brewer said, “the
more energy required to perform the mission, the greater the
advantage to be gained by using a high energy fuel”
factors that determine the performance increase with hydrogen.
#5 Tank parasitic drag penalty
Tank surface/volume ratio (Blended wing body aircraft (BWB) or flying
wings unsuited for hydrogen propulsion, since multiple small tanks
aircraft propulsion FAQ
Why has no one done this before?
remained extremely cheap up until the 21st century, discouraging the
development of alternatives, that is hydrogen, despite the
performance gains attainable. The price of kerosene still remains
under $2/gal, thus we are strongly incentivized to use hydrogen from
low-cost energy sources, mainly hydropower, with the lowest levelized
cost of $0.85 cents/kwh. Liquefaction adds $1/kg, electrolyzer CAPEX
is $0.50/kg, in total we can confidently state hydrogen can be
produced for $2/kg for from clean sources, and $1/kg from waste or
aerospace industry is highly conservative, and unwilling to
experiment with unproven technology, capital investment requirements
are often very high, and with certification costs, it may take 10 or
more years to fully recuperate the development costs,
disincentivizing the development of new propulsion technology,
especially “unproven” ones.
experts in the aerospace industry are not even aware of this obscure
and forgotten propulsion technology, G. Daniel Brewer’s book remains
in complete obscurity. Prior to Christophe Pochari’s efforts to
revive Brewer’s ideas, virtually no attention was paid to hydrogen.
Quoting Allan Epstein from Pratt and Whitney “no one has been
able to store hydrogen at less than 10% hydrogen by weight, the rest
is the tank” His comment summarizes the stance of the current
aviation establishment, and indicates the broader industry being
almost completely unaware of G. Daniel Brewer’s work and research, of
which is freely available on the internet.
Is it safe?
concerns are likely to arise as an argument against a hydrogen
propulsion system. Hydrogen will combust at a significantly higher
rate than Kerosene. An Ignition source is most likely to occur as a
result of a hard impact from a crash. The minimum ignition of energy
(MIE) of hydrogen and kerosene is well below even the lowest level
impact force that would cause an ignition. In other words, a violent
impact, lightning strike, engine failure, foreign object damage,
drone strike, or an onboard fire, will ignite kerosene just as easily
as liquid hydrogen. A sufficiently violent impact will cause a
fracture in the fuel tank regardless of whether it is hydrogen or
kerosene. The only major difference will be the manner in which
hydrogen will detonate compared to kerosene. Kerosene will detonate,
and then slowly burn in a deflagrative manner. Hydrogen will almost
immediately detonate completely leaving no residual fuel to burn. G.
Daniel Brewer was firm in his belief that hydrogen-fueled aircraft
would be significantly SAFER than kerosene-fueled aircraft, thanks to
the high flame speed of hydrogen, long periods of deflagration upon
impact inherent to jet fuel is no longer an issue with hydrogen,
allowing more time for passengers to escape.
Is it really possible to double the range?
This all boils down to how smart the designer is.
the designer chooses a tank with a fuselage integral tank with a low
surface/volume ratio, then yes the designer can realize tremendous
increases in range, doubling is realistic with the same payload as
the max range under kerosene.
How do we plan on actually building a jet, is that something only
large corporations can do?
company is a design and innovation company, led by its founder
Christophe Pochari, who is solely credited with reviving and bringing
back Daniel Brewer’s work to the mainstream of aerospace propulsion.
Our company will use established aerospace manufacturers to carry out
the manufacturing and assembly in China and India, Pochari Hydrogen
provides only the basic design and idea, albeit a revolutionary and
game-changing idea. Our main goal is to promote this technology and
idea, and find people with the necessary manufacturing capability.
fluid dynamics is done with Patrick Hanley’s Stallion 3D, Patrick
Hanley is a follower of Christophe Pochari on Twitter. Composite
fuselage design and fabrication is done in China. Powerplants, small
turbofans, are built in house using turbomachinery parts from
Shandong Yili Power technology LTD. The turbofan is based off the
proven all centrifugal compressor PW100 turboprop architecture,
converted to a turbofan.
What are the main differences between hydrogen and jet-fueled
powerplant differences are minimal.
combustors are slightly different for hydrogen fuel, the principle
difference is they are significantly shortened. Nothing in the
powerplant itself changes except the fuel delivery system changes.
Liquid hydrogen is pumped from the tank with two high-speed
centrifugal pump, then the liquid hydrogen flows through the supply
line to the engine vaporizing along the way and subsequently raising
the gas pressure until reaching 150 psi where it is injected in the
combustor. A separation between the low-pressure liquid tank and the
higher pressure gaseous hydrogen is required, dual centrifugal pumps
provide this separation.
liquid hydrogen pump is placed right outside the rear of the tank
towards the end of the aircraft, the pump is mounted directly to the
tank, the second pump adjacent to the first pump, the higher pressure
liquid is then routed to the engine in small diameter aluminum
piping, serving essentially as a makeshift heat exchanger to vaporize
until sufficient pressure is reached. Only a certain margin above the
combustion chamber pressure is required, this is in the range of
Airframe and aircraft architecture.
main difference with the airframe and fuselage is the integration of
the liquid hydrogen tank. The fuselage is designed with an optimal
surface/volume ratio, enabling sufficient volume to store the liquid
hydrogen necessary to perform ultra-long-range missions.
basic aircraft architecture remains identical.
architecture is a pressurized tubular fuselage with a low wing
monoplane configuration with a T-tail with rear-mounted engines. The
center of gravity is not altered, in fact the elevator authority is
increased due to the longer fuselage. The only possible disadvantage
to hydrogen aircraft is reduced agility due to the larger fuselage,
which makes the aircraft “fatter” resulting in more drag,
which impairs agility, business jets are not fighter jets, smooth
flight characteristics are desired, so this is not an issue.
Fuel containment and tank design
design is arguably most critical element of a hydrogen aircraft.
want to maintain the lowest pressure possible in the tank, to reduce
stresses on the tank wall skin, but we also need to achieve
sufficiently high pressure to overcome the pressure inside the
combustor through vaporizing liquid hydrogen pumped from the tank. To
reduce tank wall stress, the fuselage-tank section is pressurized to
11 psi, while maintaining 21 psi in the tank. In the absence of
pressurization, significantly more stress is imposed on the thinner
less strong aluminum tank wall. By pressurizing the tank-fuselage
section, we transfer the majority of the pressure differential
stresses to the stronger carbon fiber skin.
fuselage-tank section is comprised of a 3mm thick outer skin, made of
Toray T1100 carbon fiber, a spacing to separate the insulation from
the skin and the tank.
carbon fiber is sheltered from the low-temperature tank and
insulation by a layer of air. The monocoque structure comprised of
the outer carbon fiber skin and aluminum tank results in an extremely
rigid fuselage-tank section.
tank is fastened to the outer skin with high strength epoxy, no
mechanical fasteners are used. Stringers are bonded to the carbon
fiber skin, then to the aluminum tanking, forming a fully integral
fiber, although much stronger than aluminum, is not attractive for
continuous use at cryogenic temperatures, carbon fiber becomes
brittle at low temperature, microcracks can also develop due to the
differential in the coefficient of thermal expansion of the
individual fibers. In addition, most resins used to bond composites
become brittle at low temperature. Thus metal is the most attractive,
among the different alloys available, aluminum-lithium provides the
highest specific strength, or commonly referred to as strength-weight
ratio. Aluminum-lithium is higher even than titanium, the second most
attractive option for tank wall material. Aluminum lithium 2195
actually becomes stronger at cryogenic temperatures.
insulation is placed directly on the outside of the aluminum tank.
Vacuum panels insulation, comprised of a membrane wall, used to
prevent air from entering the panel, a panel of a rigid,
highly-porous material, such as fumed silica, aerogel, perlite or
glass fiber, to support the membrane walls against atmospheric
pressure once the air is evacuated. These panels manufactured by
NanoPore Incorporated, Albuquerque, NM, provide the lowest thermal
conductivity with the lowest weight. The thermal conductivity, when
accounting for the extremely low surface temperature when the tank is
full of liquid hydrogen on the ground, can be as low 0.0025 W/m-K.
These vacuum panels provide lower thermal conductivity to mass ratios
than S-180 spray-foam insulation. The vacuum panels are specially
formed to take the shape of the tank, and fit between the
frames/stringers. Foam is sprayed around the seams and inside the
frame volume, minimizing thermal bridging.
summary, the tank is actually very simple and based on mature and
proven technology and structural configurations. The insulation is
light-weight and provides manageable boil-off when the aircraft is
not in flight. The weight of the entire fuselage-tank section weighs
1.18 lbs/ft3. This translates into 2700 lbs for a 4700 kg tank,
providing nearly 17 hours of flight time, or 8700 miles. The
additional drag (Flat plate drag based solely on wetted area) from
the 1200 square foot wetted area is 0.46 lbf/ft2, resulting in 550
lbs of additional thrust required, resulting in a fuel burn of 58
kg/hr, 22% higher than without the hydrogen tank, this reduces the
L/D from 17 to 13.2, approximately the same that G. D Brewer found.
This calculation is very easy to perform, simply by taking the total
zero-lift drag and dividing by the wetted area, then multiplying by
the wetted area increase.
main focus is the development of an ultra-long-range light business
jet, but many other types of aircraft would benefit tremendously from
hydrogen propulsion, mainly narrow-body airliners and
In the case of a narrow-body airliner, such as an
A319, we could extend the range with an acceptable payload from 3300
miles to over 7600 miles, allowing small narrow-body aircraft to fly
much more profitable transpacific routes. This would give airlines
the option to purchase a more affordable and smaller aircraft, that
can land and operate from smaller airports with lower landing fees.
Another benefit of narrow-body aircraft is it’s much easier to fully
occupy the aircraft in a shorter period, allowing for higher and more
profitable utilization. In summary, this narrow-body would give
airlines a viable alternative to wide-bodies for transpacific
Helicopters could be designed to fly longer range
offshore oil and gas missions, or fly similar distance with more
payload. The main application of civilian helicopters is off-shore
oil/gas, which currently suffers from depressed activity, when this
improves, Pochari Hydrogen will begin designing a hydrogen-powered
10,000 lb class rotorcraft for long-range missions. Currently, the
longest range civilian rotorcraft is the Leonardo AW139, capable of
flying 750 miles with a sufficient payload to carry 15 oil and gas
workers, we can improve this to 1400 miles.
The third type of
aircraft would be a supersonic business or passenger jet. This
type of aircraft was demonstrated to the most attractive application
of liquid hydrogen by Daniel Brewer (1975), but more recent analysis
from computational fluid dynamics, and better understanding of wave
drag, may result in this not being entirely correct. The reason is
simple, at supersonic speeds, a turbofan engine cannot function, a
turbojet or very low-bypass turbofan is required, typically these
engines have much higher specific fuel consumption, typically over 1
lb-lbf-hr, instead of 0.70 lb-lbf-hr for subsonic turbofans. As a
result, the higher fuel consumption adds up the course of the flight,
resulting in the fuel load fraction being much higher, incentivizing
to a greater degree the use of a higher energy fuel. But there’s a
caveat, as we previously illustrated, in subsonic flight, the
airliner fuselage, 20 feet in diameter, with a wetted area of 9500
square feet, is only subjected to 4400 lbf, but in supersonic flight,
this is increased tremendously, to 80,000 lbf (Bjorn, Fehrm,
2018). The source of drag changes from subsonic to supersonic,
skin friction is no longer the dominant form of drag, rather, wave
drag appears, in great magnitude. This necessitates a much higher
fineness ratio, forcing us to reduce the fuselage diameter, and
elongate the fuselage, the goal is minimizing the frontal area as
much as possible to minimize wave drag, the theoretically lowest wave
drag shape is a Sears/Haack body. The “area rule” “Whitcomb
rule” is also critical for minimizing wave drag, but since this
forces the designer to reduce the thickness of the fuselage to
accommodate the increasing frontal area of the wing, this means our
hydrogen tank is forced to be smaller. In supersonic flight, the
ideal fineness ratio is over 20, for subsonic, it’s only 4. (Roskam,
Jan, 2017). The low ideal fineness ratio allows for very low
surface/volume ratio LH2 tanks, reducing weight and wetted area
penalty. The total drag penalty in supersonic flight is much
higher, and not fully compensated by the additional fuel consumption.
As a result, supersonic aircraft powered by hydrogen will provide a
smaller advantage over kerosene.
The fourth applications is
defense-related, mainly long-endurance fixed-wing UAVs, such as
Predator drone type aircraft, an increase in the flight-endurance of
100% could be more than attainable. The second defense application
would long-range bombers and strategic air-lifters, allowing for more
payload and flight endurance in the case of bombers. These defense
aircraft are obviously out of the development scope of small civilian
aircraft manufacturers, but nonetheless remains very promising
business opportunities. Daniel Brewer (1991) argued liquid hydrogen
was extremely promising for military aircraft.
GW multi-purpose ultra-long range light jet with liquid hydrogen
Max L/D cruise: 13.2, 22% lower than Jet Fuel equavelant.
volume: 400 ft3
loading: 74 lbs/ft2
load: 15,700 lbs
burn: 263 kg LH2/hr
altitude: 51,000 feet
capacity: 4700 kg
LH2 tank weight: 1.2 lbs/ft3: 13,180 lbs system weight total
Pochari Technologies has invented a sliding center of gravity system for rotorcraft to eliminate limitations faced by “weight and balance” requirement in conventional rotorcraft. The turboshaft and main reduction gearbox are fixed to the fuselage, a proprietary shaft extension mechanism allows the 90′ bevel gearbox section and main rotor shaft to slide the desired length in the longitudinal direction of the fuselage depending on the CG range required. This innovation allows for greatly enhanced mission flexibility as a result of the wider CG range allowable and is especially complimentary to our VED technology. When a load is picked up in the VED capsule, it’s ideal to have the CG directly over the center of the capsule. Once the capsule is retracted, the load can be transferred to the fixed fuselage section on either side of the capsule, as this occurs, the CG is slowly shifted to either side until perfectly balanced. The implications beyond complimenting VED technology of RCG are enormous. As fuel is burned during flight, the CG changes, with this system, the fuel tanks can be placed in the rear of the aircraft rather than underneath the bottom of the fuselage as centering the fuel mass is no longer necessary. Attack helicopters can store munitions outside of the CG center range without concern of shifting CG as the ammunition is consumed. Utility helicopters, cargo or passenger carrying aircraft can carry the load outside the CG range by simply shifting the CG position. Loads of varying density can be carried in the aircraft with less constraint. Personnel, with relatively low density, can be placed in the forward half section of the CG range, then a load with higher density (a cargo pallet) can be placed in the rear half section of the CG range. The CG sliding range is designed to be between 20 and 24″ for an 8,000 lb GW aircraft. A rail the length of the desired CG range constructed out of carbon fiber is lined with a metallic liner. On this metallic liner, a high friction rubber liner is also placed. A mechanism connecting the drivetrain module and the rail allows for sliding and locking of the location. Multiple small roller retracts from the rail slide mechanism, once the rollers retract, a friction pad is extended, providing a tight connection between the friction pad in the rail mechanism and the high friction liner on the rail. The system has gone through feasibility analysis and found to add negligible additional weight and well worth any additional technical hurdles considering the immense performance gains.
“Helicopters are loaded, unloaded and reloaded with different cargoes. The center of gravity of a loaded fuselage changes in location from load to load depending upon the load position in the cabin. This often requires readjustment of load position or careful initial distribution of load components in order to end up with the position of the center of gravity within a limited field. When the center of gravity is thus positioned within the limited field, the aircraft may then be maneuvered within the limits dictated by its design with out difficulty. When a given ship is certified by the governmental authorities, the CG field, size and location are certified and specified. The ship, once certified, cannot legally be operated with loads such that the CG is outside the certified field”
Pochari Hydrogen has invented a revolutionary propulsion technology for trucking applications. A zero carbon and zero nitrogen oxide emission powerplant that does not use fuel cells or lithium-ion batteries. This powerplant is called the Pochari closed-cycle hydrogen engine. This closed-cycle power semi-truck will utterly dominate the global trucking industry. The world needs a zero-emission yet affordable powerplant, so far those do not go together: Enter Pochari Hydrogen. More information available here https://pocharihydrogen.com/2019/03/01/closed-cycle-hydrogen-internal-combustion-engine-technology/
Pochari Hydrogen’s CHP701 is the world’s first liquid hydrogen powered turbine helicopter. Development will begin in the early 2020s. Pochari Hydrogen utilizes hydrogen stored in “cryogenic” state in carbon fiber tanks lined with an aluminum liner to minimize permeation. The liquid hydrogen is pumped via a “cryopump” from the liquid tank into a heat exchanger connected to the exhaust pipe from the turboshaft engine. Once the liquid has vaporized it immediately rises in pressure to up to 1000 psi where is it injected into modified combustors designed for hydrogen’s unique combustion characteristics. A small helium tank is used to store sufficient quantities of helium gas that serves as a pressurant. The liquid hydrogen tanks needs to maintain a minimum pressure of approximately 30 psi. Due to the nature of cryogenic systems, a very elaborate insulation system is required to minimize excessive “boil-off”. The insulation used is a state of the art vacuum insulated panel system that is lined around the outside of the tank. The insulation is formed in two large uniform shells that are joined in the middle. The middle seam is sealed with a recessed strip of vacuum panel. The uniform shell design is meant to minimize thermal conductivity by eliminating gaps and seams. The tank is fully “modular” meaning it is detachable and can be easily replaced, refilled and maintained. The modularity also allows for the pilot to release the tank in flight in the case of an emergency event that could lead to an impact violent enough to cause a potential detonation. The tank wall is 0.15″ thick aerospace grade carbon fiber reinforced polymer. The tank is designed as a semi-monocoque structure, providing excellent rigidity. “Bulkheads” or formers are placed every 18″. The tank both suspends from the upper cantilevered structure and bears at the bottom section of the airframe. The tank is attached to the airframe via UHMWPE straps wrapped underneath the insulation. The tank is isolated from the vibrations of the rotorcraft via multiple small air isolation mounts. The tank can be easily released and carried with a special dolly cart. The estimated cost of the modular tanks is $100,000. The tanks have a lifetime of around 4-5 years. A forward facing tank is the ideal configuration to minimize structural weight and to allow clamshell doors in the rear of the aircraft which is highly useful for air medical operations. This unorthodox configuration requires a “virtual” flight control system as the tank is placed directly where the cockpit would be. Since autonomy and remote control appear to be the future, this not a significant issue. Three smaller tanks can be installed externally, under the fuselage, and on both sides similar to auxilary fuel tanks on the UH-60. Pochari Hydrogen has considered this configuration but due to the lower volume/surface ratio (a number very important for cryogenic hydrogen aircraft) is much lower resulting in tanks approximately 30-40% heavier than fuselage mounted tanks. Thus we have concluded this is an unattractive option.