Problems and Concerns MotorTrend Sees
Naturally, we had questions about the Tomahawk and its potential operation in an automotive application, which TTX addressed below.
MT: Even with minimal heat rejection, would thermal expansion and particulate contamination from internal or external sources threaten the tight tolerances required?
TTX: Aerospace applications would use precision-cast, machined titanium rotors, while aluminum machined to a less precise spec should suffice for automotive use. There is a provision for centrifugal brush seals. No airbox is envisioned; spinning the air intakes at engine speed centrifugally excludes dust and air contaminants obviating the need for air filtration.
MT: What about the friction of all those rotors against their housings?
TTX: Coating them with impregnated carbon-graphite materials, titanium-nitride, and hard anodizing will minimize friction, which starts out way less than with triple-ring sealing of a V-8 piston engine.
MT: Would variances in air/fuel charge and/or spark timing/power across the three simultaneously timed combustion events per revolution induce dynamic imbalances?
TTX: The simplicity of the valve systems allows for precisely matched flow profiles. The engine’s many rotors also serve as flywheels able to smooth out such variations, and combustion chambers can be selectively switched off. The engine should be able to run without complex computer control, but the development process will quickly settle this issue.
MT: Is the maximum expansion ratio sufficient to extract meaningful work?
TTX: At the extremes of boost pressure and/or exhaust valve timing, the expansion ratio approaches 30:1, which should be more than sufficient.
MT: In an automotive industry heavily invested in transitioning to electrification, has it been hard to find enough venture-capital dollars to invest in such a novel concept?
TTX: Astron Aerospace and Liquid Piston have both garnered VC funding; TCT just needs to make its case to the right venture-capitalists, now that initial computer modeling is nearing completion.
MT: What do you say to people who contend the Tomahawk concept is overly complicated and features way too many high-precision parts?
TTX: A complete parts count adding up every bolt, nut, magnet for the starter/alt, etc. comes out to about 465 total parts with the truly unique parts count being maybe 20 percent of that number. A typical four-valve VVT boosted V-8 has roughly twice that number, and the TTX should weigh considerably less. So, while some TTX components (such as the rotors) will be relatively expensive, the overall cost is still projected to be competitive, especially when matched to an automotive application’s reduced power and safety requirements.
MT: Could thermal distortion as the engine heats up be problematic, given that the heat isn’t applied uniformly to the entire engine?
TTX: It generates a fraction of the normal waste heat generated by typical production ICEs, and ceramics will greatly reduce thermal distortion.
MT: It seems changing the main combustion chamber spark plugs could be a maintenance nightmare.
TTX: Indeed, the current design would require the removal and dismantling of the engine to access all plugs. Using extremely long-life spark plugs should mitigate this.
Trick-Cycle Turbine Ltd. is still early in its journey of development and commercialization—so early that MotorTrend was chosen to detail the engine’s technology. Next steps are to seek investors and up to $2 million in funding to build the prototype engines needed to validate the impressive efficiency predictions computer models are suggesting for the Tomahawk Trick-Cycle Turbine engine. And then, if the prototypes behave as expected, TTX hopes to demonstrate the engine’s lofty output and impressive efficiency by employing them to break land-speed and aviation global-circumnavigation records. MotorTrend certainly admires the audacious confidence of Trick Cycle president Huff and his team, and we’ll be monitoring the company and its Tomahawk closely as it’s developed.