Austral
Aerospace
Jekkora Space Plane Project
1. Overview
The Jekkora Space Plane is
- A sub-orbital flight reaching over 100kms altitude
- An orbital flight lasting over three days
- A polar orbital flight lasting over three days
- A docking with the ISS [or Mir*]
All missions will return to the launch site.
In addition, Austral Aerospace has set the following conditions on itself:
- All launches to be from Woomera
- The spacecraft will be built as far as possible from components that have been part of Woomera programs. A successful result will look like a flying junkyard. An unsuccessful result will look like a non-flying junkyard.
[* I thought that the aim of the Cup was to get things as realistic as possible. If I wanted to do a Mir rendezvous, I need to build a submarine, not a spacecraft. Hmm, there’s an idea …]
2. Specifications
Name: Jekkora Space Plane
“Jekkora” is an Australian Aboriginal word for “spear”. This seems only appropriate, as “Woomera” is an Australian Aboriginal word for “spear thrower”. The vehicle is entirely constructed from spare parts – the main thruster (and fuselage) is from the British Black Arrow of the 1960s, the wings and stabilizers taken from an F-111, and an auxiliary (orbital maneuvering) thruster system is based on the third stage engine from the disastrous Europa vehicle of the late 1960s. The leading edges of the wings and nose are coated with ablative material taken from the Black Knight re-entry test vehicle.
[Click on the coloured picture to get a description of the function, mass and provenance of all the bits]
Core diameter: 2m
Wingspan (max.): 20.2m
Wingspan (min.): 13.2m
Mass: 8,185kg (empty, but with cargo/payload), 28,125 (fuelled)
Main
engine:
Bristol Sidley Gamma-8
Propellants: 16040 kg of H2O2/Kerosene, with externally-mounted tanks holding up to a further 16,000 kg.
Thrust: 234,800 N (Vac.)
Isp: 2597 m/s (Vac), 2460 m/s (sl)
Orbital maneuvering system - RCS plus two auxiliary thrusters along the x (hover) and z (main) axes:
RCS thrusters: 16 SE-9-5 thrusters each giving 196N at 2940 m/s Isp
Auxiliary thrusters: Two 23,325 N Astris engines at 3040 m/s Isp (Vac), 2560 m/s Isp (sl)
Propellants: 3,900 kg N2O4/Aerozine-50
Boosters – runway takeoff configuration:
Boosters: Four wing-mounted Antares-2 boosters (taken from the second stage of the SPARTA stack)
Thrust: 93,126 N each
ISP: 2872 m/s (Vac), 2690 m/s (s/l), giving them a burn time of c. 33 sec (just enough to get it off the ground)
Propellant: Solid; 1,100 kg each.
Boosters – vertical/rail launch takeoff configuration:
Boosters: Two Redstone boosters (taken from the first stage of the SPARTA stack)
Thrust: 414,060 N each
ISP: 2600 m/s (Vac), 2303 m/s (s/l)
Propellant: 25,315 kg LOX/Alcohol each.
First Stage
Engines: Eight A-6 (Redstone) engines
Thrust: 3,312,480 N
ISP: 2600 m/s (Vac), 2303 m/s (s/l)
Propellant: 182,160 kg LOX/Alcohol, with an external tank holding up to 120,000 kg more.
First stage boosters
Boosters: Six boosters, each using seven Raven-4 engines as used on the veteran Skylark sounding rocket. J
Thrust: 448,715 N each
ISP: 2525 m/s (Vac), 2420 m/s (s/l)
Propellant: Solid; 13,860 kg each.
3. Development diary
30 December
First
Orbital Flight: The Jekkora reached a circular
orbit of c.174 km altitude. It completed
six orbits before landing safely at Woomera. Reentry was perfect, with reentry
temperatures so low that there were almost no reentry flames generated. Angle of attack remained below about 2.5° at
almost all times, except in the upper atmosphere (c. 80 -100 km) where it completed a large
sweeping glide turn over the south Indian Ocean as it lined up its approach to Woomera, and AOA reached 7°. Takeoff was
Annotated telemetry
of the flight is available. The
thumbnail to the left links to a set of screenshots of the flight.
26 December
A few more lost days because of coding programs. I tried to refine the aerodynamic model -- essentially creating a new instance of vessel each time something separated, with the airfoils positioned differently (and more accurately) in each configuration. Eventually, I gave up -- it kept crashing to the desktop. I'll sort it out some time, or just wait for the next version of Orbiter, which will no doubt contain a "delete airfoil" function, the absence of which in the current version has created all my problems.
Oh, is to there are now even more boosters. There are six solid fuel boosters, each of which contains seven Raven-4 engines and about 6000 kg of propellant. If you check the entry below for November 2, you'll see I joked about tying together eight Skylark rockets with string. Well, that's just about what I ended up with.
20 December
A “lost week”. I decided to structure the code for the .dll, as it had turned to spaghetti with all the bits and pieces I had added. There are fully 48 different configurations, which I converted to a lookup table. I also tinkered with the keyboard controls and the aerodynamic model (again). The result? Completely bizarre and unpredictable bugs and crashes. I eventually tracked it down to treating “double” as “int” somewhere deep in the code … a week later.
12 December
OK, now I
have added everything including the kitchen sink. There is a pair of external fuel tanks to
prolong the burn time of the main engine;
a first stage (8 A-6 engines) also with an external tank; I also spent
all weekend building a rail launcher that runs alongside the runway then on for
15km. Getting it to go “straight” –
given that the curvature of the earth is a factor here – took the best part of
a day. I still can only get 6 kps …
7 December
Well, the
Redstone-boosted launch configuration has now been implemented. In this setup, it launches standing on its
tail; the Redstones and the main Gamma-8 engine fire
simultaneously. The Antares
boosters are optional, but can give it a little more dV
after MECO. All very well, but it does
not achieve more than about 3 km/s maximum.
I’m going to have to do something different; either a first stage
(perhaps another Black Arrow), or an external fuel tank to give the main engine
a longer burn time. But the latter is
just too close to the Shuttle to be interesting.
4 December
I’ve just had a very frustrating few days finding and fixing a CTD when the boosters are jettisoned (only in certain configurations). I also found a little error in the constants calculating the swing-wing aerodynamics; it should be a little more “realistic” now.
28 November
First sub-orbital (100km+)
flight. The Jekkora reached
a maximum altitude of 116km, and returned safely to Woomera. The flight began at
27 November
Well, it’s ready to go. I have put the sub-orbital configuration up as an addon (my first!) on orbithangar. Now I’d better learn to fly it and go for the sub-orbital prize, or someone else will get there first. Maybe that’s not such a bad idea? I could advertise for pilots … and charge $250,000 for the privilege of flying it? Virtual dollars, I guess.
26 November
Well, this is a bit embarrassing. I had forgotten that I was hauling nearly 4 tonnes of fuel for the OMS. I’ll need this for docking with the ISS, but hardly none for just going up to 100km. If I set the fuel to about 0.2 for the Astris thrusters, the Jekkora easily gets to 100km.
25 November
Well, the good news it that I have the aerodynamics sorted out pretty well. Thanks to DaveR and dh219 for some guidance on how to implement the swing-wing properly. Gosh, I’m astounded at how realistic Orbiter is, because the bad new is … there’s just now way this heap of junk is going to take off from a runway and reach 100km. Even with the Antares-2 boosters it can make 20km tops. Oh well. Where are those Redstones I saw lying around?
23 November
I’ve
added four Antares-2 boosters to give the thing some extra oomph on the runway
takeoff (they could also be used during the vertical Redstone-boosted launch
I’m planning for the orbital ascent).
The thing is a sight to behold steaming down the runway at Woomera. I’ve got
very familiar with those white lines, let me tell you
… Now I just have to do some real work on the aerodynamic specifications to get
the values as realistic as possible.
19 November
I have my head down doing boring stuff that doesn’t lend itself to screenshots – like writing the code to calculate the coefficients of lift and drag while the wings are swinging. I’ve got functions that work now – now I just have to try to make sure the values are as “accurate” as possible. Continuing to pretend this might actually fly if I built it for real …
14 November
First
test flight today. I haven’t finished
the aerodynamic parameters, so it’s all a bit dodgy, but it reached 27.7km from
a runway takeoff with no boosters. I was
pitching up at about 40 degrees most of the way – I’m sure it can go much
higher if I just point it straight up J. I’ll sort out the aerodynamics properly (some
of the parameters are inherited from the DG), implement the swing wing, then
take it for a real test.
12 November
Finished the animations – gear, control surfaces, and the swing-wing. I’ve calculated – more or less – the mass of the components (which you can see by clicking on one of the colour-coded pictures in the “Specifications” section) – so I’ve started coding. The next tricky bit will be calculating the change in aerodynamic parameters as the wings swing. I may fudge and just set the best parameters I can for fully extended and fully swept wings, then simply do linear interpolations of the middle positions.
9 November
The mesh is
finished. It needs a bit of paint – white, I think, as I’ve got plenty of
white left over from those lines down the middle of the runway. I’ll
leave the textures till after I’ve sorted out the coding. I’ve got a
pretty fair idea of the internal systems and their mass now (way too much), and
I’m keen to get the thing off the ground. Now for some
serious research on the aerodynamics of variable-geometry aircraft …
6 November
Well, the basic design is there, and at least I know the size of the thing and the thrust of the main engine. I’ve got a lot of empty space to play with in the main body – I can make some increase in main fuel tank (this thing flies on kerosene!), as well as house the attitude thrusters and fuel, and the swing-wing mechanism. I’m also going to need some fairly decent total thrust while in orbit, for maneuvering and for the re-entry burn. Maybe at -90 degrees to the z axis, so it can double as a hover engine and take the edge off the vertical velocity at landing approach.
5 November
My original thought was to bolt some wings onto a Redstone, but that would be … unfeasible. However, taking two 6m-odd Black Arrow first stages – one with the Gamma-8 engines intact – and using that as the basis of the fuselage is how I’m thinking. At least, that’s what the model is starting to look like. I’ve put the wings on – this thing looks like it would never fly. Sure, it will go up – and luckily Orbiter doesn’t check to see if the stresses are so great the wings fall off on the way up. But will it come down with any sort of trajectory even an emu would be proud of? [An emu is a flightless Australian bird].
For wings, I’m sticking with the theme of “realism” and using some old RAAF F-111 parts – I quite like playing with the idea of variable geometry wings. I’ll have to coat the leading edge with some sort of ablative goop to at least pay lip service to re-entry temperatures, but that will increase the mass of course. I should really write some code that makes the thing fall apart when critical dynamic pressures and temperatures are reached, to give an element of realism.
3 November
Well, here’s the basic concept, as I outlined it today. I’ll leave this here to show myself how wrong I could be …
- It will be a spaceplane, but will have a detachable nosecone/crew section for escape purposes. The nosecone may end up being the component that achieves orbit, returning by parachute, but I’m not going to give up on getting the whole junkyard up there just yet.
- It will have multiple launch configurations:
- Theoretically, it should be able to make a runway take-off under its own steam. I’m looking at small, low-thrust, liquid-fuel boosters to provide take-off velocity and get it airborne.
- Ideally it will reach 100km sub-orbital launched underslung from a C-130 Hercules, or from a vertical launch with solid rocket boosters.
- For orbital flights, it will need at least one main stage.
- It will have variable-geometry wings, which will, in theory, allow it to behave more like a plane or more like a rocket in atmospheric flight (hence permitting the different configurations above). How a variable-geometry mechanism is supposed to stand up to orbital re-entry velocities … I’ll just have to find out.
2 November
I’ve had a good time rooting around the old sheds and hangars at Woomera looking for spare parts I can cannibalize for the spaceplane. I was pleased to discover some old Redstone components from the SPARTA launches here in ’67. For a while there, it was looking as though I’d have nothing more powerful than a Skylark sounding rocket to get into orbit. Eight Skylarks tied together with a piece of string would look something like a large stick of dynamite – and probably fly like one too. I’ve also got some engines and stages from the British Black Knight and Black Arrow programs to play with.
1 November
I have spent
the day getting Woomera ready for launches
again. Hardly anything’s flown from here for years. The screen shot
shows the brand new 8000m runway that will handle the landing – that is,
presuming I can get the thing anywhere near the runway. Because of my
inability as a pilot to hit a runway five times in ten, I did consider
attaching seaplane floats instead of wheels, but thought that they might make
the vehicle somewhat …ahem … aerodynamically unstable during atmospheric
re-entry. Or launch. Or anything
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