Subject: Fwd: Hermeus Targets Mach 5 Sweet Spot For Civil Hypersonic Project

Stephen

thought this might interest you
Andy

Begin forwarded message:



Hermeus Targets Mach 5 Sweet Spot For Civil Hypersonic Project

Guy Norris

Amid the ongoing surge in civil supersonic aircraft projects, Atlanta-based startup Hermeus has unveiled details of its ambitious plan to develop a higher-speed passenger aircraft with, potentially, double the speed advantage.

Provisionally sized to carry around 20 passengers over transatlantic ranges at speeds up to Mach 5, the newly revealed aircraft project is targeted at entry into service by the late 2020s. Despite the aggressive schedule and ambitious performance targets, the company believes existing and near-term technologies are already capable of supporting the venture.

The decision to limit the vehicle to Mach 5, the defined boundary between supersonic and hypersonic, is a key factor in the near-term feasibility of the project, says the company. “Once you get above Mach 5, the stagnation temperatures within the combustor, as well as what we’d experience at the leading edge and the like, are really hot,†says Hermeus Chief Technical Officer Glenn Case. The X-15 hypersonic research aircraft, for example, recorded temperatures at Mach 5 of 1,110F and 1,325F on the nose cone and wing root, respectively, while predicted equilibrium temperatures in the same zones on a hypersonic cruiser at Mach 8 are 4,000F and 3,100F.

“Current materials will work at Mach 5, but once you get out of the range of lightweight materials, you have to go to nickel-based materials, and beyond that you have to start making major airframe structures out of ceramic matrix composites,†says Case. “That’s not in the technology wheelhouse we want to operate in. We want to be engineers, not scientists.â€

By limiting the top speed to Mach 5, Hermeus also hopes to develop a viable propulsion system that depends on a combined turbine [either a turbojet or turbofan] and ramjet, but which crucially does not require a supersonic combustion engine, or scramjet. “That’s one of the things we don’t want to tackle, and that’s where the science comes in,†says Skyler Shuford, chief operating officer of Hermeus. “Scramjets aren’t science fiction like they once were. They are right there on the horizon, but there again we’ve all being saying that for 20 years.â€

Although several turbine-based combined-cycle (TBCC) propulsion concepts are under evaluation by the U.S., China, Russia and others for proposed air-breathing hypersonic vehicles and weapons, the majority incorporate a dual-mode ramjet that transitions to scramjet mode at Mach 5.5 or 6. Around this speed and above the flow passes through the combustor supersonically.

Although the Hermeus aircraft would utilize a propulsion system in which shock compression replaces mechanical compression, a ramjet would still be able to achieve efficient operation at Mach 5 by decelerating and compressing the incoming flow to subsonic speeds. “It will take a government level of investment to get an operational scramjet off the ground, but to get an operational ramjet off the ground we are talking venture capital. So, we are going to stay with subsonic combustion and deal with the higher temps, but at conditions where the ISP [specific impulse, or measure of fuel efficiency] of a ramjet is still very good,†adds Shuford.

“We do believe the technology is there to develop a Mach 5 vehicle. The key is going to be the transition to the ramjet,†he adds. The baseline propulsion system, like much of the vehicle, is in the initial study stage but “generally we are looking at a turbofan or turbojet,†says Shuford. “More likely we will go to a turbofan because of the bypass ratio for operating on the lower side of the Mach range from zero to about Mach 3.â€
Currently portrayed with a simple 2D inlet, Hermeus says the final configuration will continue to evolve. Credit: Hermeus
Referencing previous operational high-Mach systems such as Pratt & Whitney’s J58 turbo-ramjet developed for the Lockheed SR-71, Shuford says the technology is well established. “But we need to relearn it, and we haven’t had an engine that’s operated there commercially. It is a development challenge, but I don’t think it will take a miracle.â€

Hermeus, which revealed its presence in mid-May after announcing a seed-round investment led by Khosla Ventures, with additional participation from private investors, has “been in contact with primes as regards turbomachinery, and we are looking at potential partners there,†says Case. Although unidentified for now, he adds that the potential partners are engaged in high-speed turbine studies both internally and through U.S. government programs. “We have had some high-level talks,†he says. “There’s a lot of government push but not a lot of industry pull, and that’s what we represent. That’s very beneficial not only to customers but also because the government wants an industry.â€

One such effort is the U.S. Air Force Research Laboratory-led (AFRL) ATTAM (Advanced Turbine Technologies for Affordable Mission Capability) initiative. Targeting technology development for a range of next-generation small-, medium- and high-power turboshafts and combat engines, the ATTAM program has so far awarded Phase 1 contracts to General Electric, Honeywell, Pratt & Whitney and Rolls-Royce, as well as Lockheed Martin and Northrop Grumman.

The baseline vehicle configuration indicates twin tails, a 2D waverider inlet and a large wing with outer sections angled down at a relatively modest anhedral. However, the final product could look significantly different, says Case. “The drawings we have released so far are conceptual at this stage, and we are still 8-10 years away from flying something like this. But we are going through a handful of outer mold lines and crunching through computational fluid dynamics to see which configurations are the most optimal. You have to start somewhere,†he says.

“The company’s been around for six months, so there’s a lot to still be decided. But it is important to us that we use existing aviation infrastructure,†says Shuford. “We want to be able to land on existing runways, and we also want to be able to run on jet fuel. We don’t want to have to completely change the infrastructure to be able to run our vehicle.â€

Hermeus is targeting the high-end business traveler and corporate markets. “We are talking about a mostly transatlantic type range of 3,800-4,000 nm or so with 20 passengers,†says chief product officer Mike Smayda. “Compared to Concorde, the interesting thing about Mach 5, compared to Mach 2 or so, is that the faster you fly you can provide the same service to the same number of people with a smaller aircraft.â€

Smayda, like co-founders Case, Shuford and CEO A.J. Piplica, are all former employees of Generation Orbit, where they most recently led the development of the X-60A, a rocket-powered hypersonic testbed vehicle. The company’s board of advisors includes former Blue Origin President Rob Meyerson; Rob Weiss, the recently retired vice president and general manager of Lockheed Martin Skunk Works; Keith Masback, former CEO of the U.S. Geospatial Intelligence Foundation; Katerina Barilov, founder of Sparkplug Capital+ and managing director, Shearwater Aero Capital; George Nield, former FAA associate administrator; and Mitch Free, former director of technical operations for Northwest Airlines.

All I can say is WOW!! Think of Hawaii from West Coast in under an HOUR!!
Cheers,

Here's a link to various concept aircraft-

https://www.google.com/search?...=1&spf=1559425205336