Thursday, January 15, 2009

Project Farside



These are four stage rockoons that were designed to explore space at high altitudes approaching 4,000 miles. A rockoon is a rocket launched at altitude from a balloon, resulting in a very high apogee.

The goal of this project was to attempt the highest performance possible using state of the art solid rocket motors and multiple stages. This project was initiated in 1957, soon after the launch of the first soviet satellite. It is strange that this rocket was not used to attempt orbit, it probably had the performance to make a few orbits. Burnout was around 18,000 mph. An "over the hill" launch at 45 degrees over the bubble would have probably made elliptical orbits. But the payload and quality of orbit attained would have been poor, even embarrassing compared to Sputniks 1 and 2.
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"Project Far Side was a series of six low-cost, all-solid-fuel, four-stage, balloon-launched sounding rockets, each launched from a carrier 200 foot (62 m) diameter balloon, and built and used in 1957. When each balloon reached its maximum altitude of about 100,000 feet (30,480 m), the rockets fired through the balloon.

Each Far Side rocket carried a scientific payload of three to five pounds (1.4-2.3 kg) of instruments for measuring cosmic rays, electromagnetic radiations, interplanetary gases, and other phenomena. The maximum altitude reached by the Far Side rockets may have been 4,000 miles (6,440 km). This object was donated to the Smithsonian in 1965 by the Aeronutronics Division of the Ford Motor Co."

"A total of six Farside rockets were fired from Eniwetok in late 1957. The first launch was attempted on 25 September 1957, but failed due to a balloon malfunction. The next three launches in early October were also unsuccessful, because one or more rocket stages failed to ignite. The 5th and 6th Farside rockets on 20 and 22 October were the only ones to come close to the design altitude, but because of transmitter failures no scientfic data was obtained. These telemetry failures also prevented accurate tracking, and therefore no exact data on the peak altitude is available. Sources quote values between 3200 and 5000 km (2000 - 3100 miles).

A secondary goal of Farside was to test concepts for a larger five-stage follow-on vehicle, which was to reach the vicinity of the moon. However, this project never materialized."

Stages:

1st stage: 4x Thiokol Recruit solid-fueled rocket; 167 kN (37600 lb) each for 1.56 s
2nd stage: Thiokol Recruit solid-fueled rocket; 167 kN (37600 lb) for 1.56 s
3rd stage: 4x Grand Central Arrow II solid-fueled rocket; 10.1 kN (2270 lb) each for 1.78 s
4th stage: Grand Central Arrow II solid-fueled rocket; 10.1 kN (2270 lb) for 1.78 s

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Some reasons why this is an exceptional rocket, and why it is may favorite rocket of all: The stage ratios are nearly perfect, near to the ideal ratio of 4:1 (or in this case 16 - 4 - 1 - .25). The design of the rocket is simple, compact and really robust. The shroud that makes stage 1 more aerodynamic (but only so much is needed at launch altitudes in rarefied air) becomes the aerodynamic stabilizing surface for stage 2. Stage 4 appears to nest inside stage 3, reducing length overall. When stage 4 burns, it simply flies out of the lower four stage 3 motors. These are all fast motors, in the video one can see the rocket rapidly fly out of frame counting off new mach numbers by the second.

Above and beyond the typical rocket envy, in this I see the perfect model for an amateur program that we could build today. JP aerospace, HARC, CU aerospace, and others have planned to use rockoons for space flight. By lifting rockets to 40,000 feet or more, one can avoid much of the atmosphere and the associated aerodynamic drag. Performance improves greatly. Results to date have been mixed, and much work remains. A motor such as the simple O-10,000 would almost certainly make space from 70,000 feet. We now have newer motors including the CTI N10,000, N 5,800, and O 8,000 (in order of increasing total impulse.)

A modern day, amateur or hobby built project farside would consist of: A large balloon with a light weight tower, and a rocket made from: 4 R motors staged to 1 R motor staged to 4 M motors to finally a single M. Too complex? One might consider a single T motor, staged to an R, staged finally to a P motor, and an M. Similar performance might be found, and orbit is just within reach. Could ballistic (unguided, spin stable) rockets be launched to orbit? I suspect this would be among the simplest ways to get the first amateur (or hobby related) flight to orbit. Certainly deep space could be made. A larger rocket could be sent to or past the moon, also a very interesting challenge that the hobby crowd should consider in the coming decade. Lunar launches are an order of magnitude harder than simple orbits if they are not ballistic arcs up and back. The guidance needed would be limited in this single instance. Can they be done with a purely ballistic rocket? I suspect they can, with some very creative mission planning. But the appeal of rockoons ends with hobby attempts. When it comes to complex missions, large payloads, and reliable results, there is simply no replacement for large and expensive bi-propellant rockets.


Project Farside video (note the propaganda message against the soviet progress in space.)




An amateur flight launched from a rockoon, with impressive but somewhat limited results: the rocket did not make space, but almost... This team chose a large hybrid rocket with giant fins. The rocket was very cool, but fragile and complex. As above, I strongly suggest the use of a simple hobby motor. Back when the CATS prize was active, teams had to loft 10 kg to space in the form of a metal slug. With that extra load, I think CATS teams should have gone with a P motor, or at the very least a good O motor. Notice that the rocket failed to even burst the balloon, and was never quite stable. This means that higher thrust is needed. Any of the above motors (N 10K, 5.8K and O8K) would, if placed in a very light CF airframe, achieve massive accelerations like 25Gs or more. Also launching a bit lower, say 70,000 feet, would reduce the complexity and risk of the mission, and allow for better aerodynamic guidance. The gains from launching at 70,000 feet (already nearly .25 of space) are still significant. An O motor launched at sea level would maybe get 30,000 feet agl. The same O motor at 70,000 feet should be expected to gain more than 200,000 feet! Clearly drag is the largest enemy of small and medium-sized rockets.


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Sources:
A great source for many rockets
A paper that you probably cant get
The model I hope to visit some day soon

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