A guest post by Joseph Friedlander
The Bolonkin’s hypersonic linear electric engine (HABE) was described recently from a paper by Alexander Bolonkin. There was a concern that the hypersonic sliding of contacts could be a design flaw or problem.
Working hypersonic sliding contacts have been done but I am sure shoe life is short. Below is proof it can be done— this is the fastest pair of rocket sled records –about Mach 10 (2.5 km/s +) in 2003.
Note that lunar escape velocity is on the order of 2.38 km/s (5324 MPH) so even the 1982 test could have done that. I have not seen anyone mention in an an article about using a rocket sled for export of passive payloads from Moon to Earth—so consider this a first!
Reading the paper it is clear that the HABE train is hard to visualize. The carrier is railroad like to suspend the thing before sufficient lift is generated. From 200 m/s and onward the tracks are left behind and the ship detaches from the ground engine. There is sliding electrical contact between sacrificial shoes and the electrical bus of the launcher. This is not a coilgun. There is a similarity to a railgun but it is not exact.
The ground track installation is usable as a ground railway, a ground railway launched aircraft and as the initial boost part of a space launch system. The difference is in the final speed and separate compatible hardware may be needed for each class of vehicle.
Professor Bolonkin believes the US Navy has solved (how economically is unclear) the problem of sliding hypersonic railgun contacts because they are moving to sea trials of a 4 km/sec railgun. Just twice that velocity puts us into orbital boost velocity. (More may be needed to compensate for gravity and drag loss, etc)
Note that disposable iron electrical contact “shoes” that are sacrificial (worn out) with which make actual hypersonic contact at each launch with very spectacular display are expensive but are not the worst alternative. They will cost $1000 per set of contact points and be a small part of the expense of a 10 ton launch ($100/ ton additional cost)–compare to routine cost of a helicopter at $8000 per flight hour.
Bolonkin says that –
Electric contact and wheel contact are different and independent.
Electric contact is SPRING contact.
Over speed 200 m/s the accelerator is as a hovercraft (as a rocket sled, as very low altitude aircraft in a (sonic boom containment) tube).
Regarding physical wheel contact, then below 200 m/s is no problem, above, there is ZERO WEIGHT ON WHEELS (i.e. in flying condition few planes use their landing gear wheels) also no problem of wear on the ground rails but there would be an awesome sonic boom in the containment tunnel. But that is so outside the tunnel does NOT have an awesome boom, i.e. remote from the right of way is undisturbed countryside.
There are many issues and unknowns; although simple collision can destroy objects at 300 m/s (such as F-4 fighter on rocket sled hitting concrete wall )
sliding electrical spring contact can generate a cloud of plasma that both protects the rest of the contact from erosion and that should conduct electricity at contact point –one key question is the rate of consumption as the electrical contact reaches final velocity.
The contacts will probably be disposable in each flight; determining that is part of the testing and research. Bolonkin’s design is an attempt at high efficiency and less plasma compared with conventional railgun type launch devices.
The Previous Description
The main idea of the offered ground hypersonic electric engine is segmentation of the acceleration track on small special closed-loop sections (12.5 – 100 meters) and a system of special switches which allow return of the magnetic energy to the system transferring it to apparatus movement. This increases the efficiency of hypersonic engine up 90% (instead of 20-40% for a railgun). It avoids the burning of rails when using the engine for long periods of time. The same idea may be used in a conventional Rail Gun.
The feasibility and practicality of this invention was designed for the purpose of using it as a space launcher for astronauts and space load, as method for hypersonic long distance aviation and as method for supersonic passenger ground rail transportation. The offered system will be significantly cheaper than the currently used MagLev (Magnetic Levitation) systems, because the vehicle employs conventional wings for levitation and the hypersonic engine is very simple. The offered system may be also used for mass launch of projectiles as a weapon.
The suggested launcher is
* very simple
* uses conventional iron rails
* does not generate high heating
* can be produced with present technology.
* A large conventional power plant is enough for launching over ten tons into orbit.
The system uses conventional iron rails which are 28 times cheaper than copper and 7 times cheaper than aluminum rails. Iron rails have in 3 – 6 times more specific electric resistance. The road with these conventional iron rails may be used as a high speed conventional rail track. That means that in the worst case scenario the cost of construction will not be lost. The longest in World Beijing to Guangzhou high-speed line (China) will open Dec. 26, 2012. A 2,298-kilometer (1,428 mile) line links the nation’s capital and the southern city will have average speed 300 km/hours. The speed record of rail train is about 580 km/hour. The offered space launcher will need an initial acceleration up 100 m/s (360 km/hour) by a conventional locomotive because HABE has low efficiency in low speed. After initial acceleration the locomotive will be disconnected from launcher. The other features of the offered road (if one will be used also as a space and long distance aviation accelerator) are following: one must be strictly rectilinear and into a light (better partially transparent) tube. Sound waves from supersonic and hypersonic flight should not disturb the nearest population.
A conventional power electric station can produce sufficient energy to operate the offered HABE but the offered HABE engine needs a set of the electric transformers to produce a high ampere electric current.
533 kilometers of launch track would be enough to launch into space using 6Gs of acceleration.
Description and Innovations
A section of the system is presented in a schematic above.
It has two rails 1, 2, sliding jumper 3 and an electric current source 11. That part is same as conventional railguns. But unlike the railgun the path is divided into small sections which are only activated when the apparatus moves along in that section. In this design, the rails contain two special motionless jumpers 14, 15 and special three position electric switches 8. Every part of the railway contains two sections 17 and 16. In the first 5 section 17 the apparatus is accelerated by the outer electric source 11. And in the second section 16 the apparatus is accelerated by the internal inductive electric energy of that part. This operation significantly increases the efficiency coefficient, saves energy and saves the rails from thermal distraction which allows acceleration over any length which can therefore reach a very high speed.
Another cost saving feature is that in this design, the railway can be conventional iron rails (not from expensive copper) and small cross-section area which allows using the conventional high voltage electric line for delivering electric energy along the long acceleration distance.
The suggested system works the following way. When the apparatus (jumper 3) located at point “a”, the switch 8 turn on to contact 10 and connect the circuit “abcde” to the electric source 11 (transformer of the high voltage electric line 12). The electric current runs into circuit “abcde”. As the result the moving force appears in jumper 3 and move the jumper and apparatus 5 in direction 6. Simultaneously the circuit “abcd” accumulates the electric energy into Magnetic field. The accumulated energy is large because the current is strong.
When the apparatus reaches point 13 the switch is disconnected from the contact 10 (from outer electric source 11) and one is connected to contact 9 and completes the electric circuit “abcd”. The electric current will decrease, but an inductive magnetic field of “abcd” hinder it and at the same time produces the electric current into circuit “abcd” in the same direction.
The offered hypersonic liner electric engine (HABE) has the following advantages over the RailGun:
1) The railgun is acceptable only for small projectile (some kg) because one cannot have a long barrel (the efficiency became the very small). That means that the railgun must have a very large acceleration not acceptable for manned vehicles. The manned vehicles can have a maximum acceleration 3 – 7 g. The HABE does not have it limitation.
2) The railgun has low efficiency in using electric energy (it losses the inductive energy). The HABE does not have this limitation because it utilizes the internal inductive energy.
3) The inductive energy of railgun in the moment of projectile leaving of barrel is released as a gigantic plasma flash and creates the thermal distraction of rails. The HABE does not have this limitation.
4) The unit length of HABE is cheaper because allows design of the path from conventional iron rails (not from expensive copper) and rail has a small (conventional) cross-section area.
5) HABE allows using the conventional high voltage electric line for delivering electric energy along the large acceleration distance.
6) HABE is able to accelerate large mass (train, hypersonic aircraft, space ships).
7) HABE may be used as engine for super high speed ground transport