MASS PROBLEMS ? NO MAS!
We have presented a case for horizontal launch with several notions to reduce mass. With Hydrogen Peroxide oxidizer we still face some high takeoff weight figures. Getting a heavy aircraft off the runway is always a challenge, especially without adding more mass for flaps and mechanisms. We can see the Concorde as an example that made strides in that direction.
By careful shaping, the Concorde wing achieved a vortex that aided lift at a high angle of attack. It had to accelerate up to speed sufficient to allow it to rotate on the main gear to do that. Then we see that vortex actually being visible in many photographs. That inspired our design to emulate this or any similar form that can enhance lift on the takeoff roll.
Since we have an in-line two stage vehicle, our challenge includes reducing the structural loads on the junction of these two aircraft. If we considered a rail launch we might have a “sled” that could provide a cradle to support the two stages. That would allow us to have only light weight landing gear for empty weight at the end of the mission. We could also provide a hydraulic lift to elevate the craft to the ideal angle of attack before even starting the takeoff roll. That will deliver the ideal angle of attack before we even start the engines. Looking at Concorde images, that AOA appears to be between 10 and 30 degrees, so our lift can probably allow us to experiment with that in taxi testing or wind tunnel evaluation.
Now if we consider a rail launch we have other issues. When a vertical launch fails it either explodes, or is deliberately blown up, destroying the rocket, its payload, and often the launch facility. Such damage could also be produced by sabotage or a sniper rifle, causing long launch delays to other missions. For our horizontal launch the vehicle might not fall directly on the rail, but it might. A rail launching system would require a dedicated facility with considerable construction cost. Adding that cost to the limited availability of sites and risk is not our goal. Having a rocket sled was a fun idea in the books I grew up with though.
Other solutions have been demonstrated in the past. The ME 163 rocket fighter used wheels only for takeoff, then they just dropped them…on whoever got in the way! The Star-Raker proposed to do the same thing, only with much larger gear and more serious damage potential.
There is a way to do this without a dramatic increase in your insurance costs. And Boeing is already doing this on a small scale. Their Phantom Eye drone has a huge hydrogen fuel tank, high mass, and little tolerance for heavy landing gear. To keep mass down they use only landing gear, leaving takeoff to a launch cart. Nothing falls out of the sky, as the cradle stays on the runway. This probably has an auto-pilot to stay on the runway. That looks like a good start that we can build on. We can add the cradle and some propulsion at the same time.
If we add electric hub motors we can begin to provide acceleration without as much fuel burn. The cradle vehicle can be heavy enough to operate on a runway in crosswinds and still be fast. Electric cars are demonstrating great performance potential and this is renewable energy without volatile fuels. Notice that takeoff is not the only drain when aircraft use fuel while moving on the ground, and waiting on the runway. The electric can wait all day without draining fuel from the flight vehicle.
The launch cradle vehicle offers protection from another hazard. The Concorde experienced a tire failure that threw debris and caused a fatal crash. A cradle can shield the aircraft from tire and other debris that could damage thermal protection or fuel tanks.
But there are other issues to consider. Launching an aircraft does not always happen in ideal weather conditions. In a crosswind, takeoff and landing can be very challenging. In flight an aircraft can “crab” of turn upwind, while the actual flight direction remains at an angle to the direction the craft is pointing. This can be difficult when you are operating as a ground vehicle, where tire scrub would be pretty severe!
But again, solutions in the past have addressed this issue. The Boeing B-52 has fully steerable landing gear which can crab at an angle up to 45 degrees during takeoff or landing.
So now we are getting a concept of the look of the future of horizontal launch. With enough mass, rubber on the ground, acceleration energy, and crosswind capability we may be “go for launch”.
In the lowered position fueling, services, and payload mating can be performed in a hangar. The vehicle can move the aircraft as needed, and wait on the runway for clearance to take off.
ON A ROLL AT THE RIGHT AOA
GO FOR LAUNCH!
This may be a stretch, but driverless vehicles may add another capacity. In an emergency, the robotic vehicle may be able to return to the upwind end of the runway and meet the combined craft for a rendezvous landing. The robotics guys are full of tricks these days! Has range control ever asked a malfunctioning vertical launch vehicle to return to the pad? Boom? How are your insurance costs?
We have not presented a completed design or even a feasibility study at this point, that will require some funding. But we approached some of the known issues with possible solutions to make the mission. You may recall we published this mass estimate compared to Spacecab projections. With the energy savings of the launch cradle, we may have cut this number down to be more favorable. If aerodynamic advantages add a little more help this may turn out to be worth evaluating properly.
Without more evaluation we cannot be sure this is the answer. But if you review the earlier posts (and click the links at the bottom left corner of each post for the next one) you will see a lot of unique steps to shave mass and drag. Is it time to dust off the horizontal launch concept again?
Our team is small, but growing and we may have some assets still under development. A project as big as this needs a lot more development. No one would object to doing this if we can offer compensation for the needed labor. It would be wise to show that competent leadership and execution can be delivered. We have part time help and advisers with some experience now.
We are affiliated with X-L SPACE SYSTEMS owner Michael Carden, and FRONTIER ASTRONAUTICS owner Tim Bendel in Chugwater Wyoming. Michael is a veteran Air Force Space Systems officer with program management experience in that role. He has also served the new space community with his firm and Beal Aerospace. His interest in ejector ramjets has us planning more development in that area. He also sells 100% HTP and better fuels to come.
Exodus Aerospace also has consulting engineers and retired aerospace managers now.
KEY EXODUS TEAM PARTNERS, AND ADVISERS:
Cunningham, Jon David
Beasley, Joseph Craig
We have other vendor teams available for air advanced breathing propulsion, airframes, and guidance systems. For prototypes we would offer design and analysis through established design firms. Fabrication teams are available who have experience from Scaled Composites and Skunk Works projects. These shops have facilities, skills, and human resources from their established customer businesses. We can offer them work without causing high overhead to investment partners.
We are recruiting partners at all levels, from interns to retirees. Mentors and advisers from the private sector or major aerospace players are welcome. We are already gathering some valuable people but we can always use more, space is a big venture. It’s time to start building the business and marketing plans.