Small launcher, Long Distance probe

[Jack wooster]

The aim of this challenge is to use a cheap launcher, to send a small probe into space and get as much exploration done as possible. The launcher, based on the Virgin jets then solid concept, is to be made of one jet engine first stage with one RT-10 Small solid booster second stage, it doesn't have to be a space plane though.

Rules

1. First stage must be one jet engine only.

2. Second stage must be one RT-10 Solid.

3. Mechjeb allowed.

4. All other parts must be stock.

5. Probe must have an apogee out of the atmosphere when the RT-10 has finished firing, out of Kerbin SOI is possible.

Submission Requirements (example below)

1. Screenshot on the launchpad.

2. Screenshot of any achievements you're claiming.

Achievements

Extra cudos for Landing

Double extra for Sample return

Triple for a manned mission, but not a one way one!

The further you can explore the better.

Eample of what I mean:

[tavert]

Propulsion in a 3rd or later stage is allowed?

[Jack wooster]

Well the probe will have an engine, but as long as the second stage as an above atmosphere apogee, a third stage would be within the spirit of the challenge.

[SunJumper]

This looks pretty good. I'll try a munmin

Actually, scratch that, jets are too difficult to use. I've had so many launch failures, it would be cheaper to use the large SRB.

Edited April 27, 2013 by SunJumper

[Jack wooster]

Double post, trying to launch whilst posting!

Edited April 27, 2013 by Jack wooster

[soranno]

with a third stage ion probe it is only a matter of time, but I`m really trying to get more out of the first 2. My best so far is only 1000km apo after the solid booster burns out

[Jack wooster]

My Kerbin SOI test was with a probe (with an engine) that only weighed half a tonne.. Th great thing about using just one jet engine is that you can tank it to over 1000m/s then when it flames out nothing is thrown off balance and you can lite up the solid.

[Istas]

Is a fourth stage allowed, as long as the first and second stages (and obtaining AP above atmosphere by the end of the second stage) are as required?

[SunJumper]

Is a fourth stage allowed, as long as the first and second stages (and obtaining AP above atmosphere by the end of the second stage) are as required?

I'd say they're practically required...

[UmbralRaptor]

Clarification request: basic jet or turbojet?

[Istas]

Launch mass: 9.04 tons taking away the launch clamp (and including the bit of fuel I already burned)

https://www.dropbox.com/s/s95w42huof9djor/screenshot226.jpg

AP outside of atmosphere at second stage termination

https://www.dropbox.com/s/l395a087h89a0d3/screenshot227.jpg

Duna encounter

https://www.dropbox.com/s/218qrnx163ibren/screenshot229.jpg

4400 km away

https://www.dropbox.com/s/xdthjhxpbkvmdt4/screenshot235.jpg

A couple years later, Kerbin encounter

https://www.dropbox.com/s/1o8w735ndk2zgim/screenshot237.jpg

Double-dip reentry

https://www.dropbox.com/s/6f7nu7demmnxx27/screenshot244.jpg

https://www.dropbox.com/s/80nc78rmkt3u8gs/screenshot250.jpg

Safe landing at KSC

https://www.dropbox.com/s/kj684xtt617q1is/screenshot254.jpg

https://www.dropbox.com/s/ziff5hws9ifboya/screenshot258.jpg

I wanted at least to get an aerocapture around Duna, but an accidental time-warp across an SOI ruined my chances for that (if I ever had them to begin with).

Still, Gusnie had an enjoyable trip.

Edited April 28, 2013 by Istas
dropbox apparently doesn't publicly direct-link images for accounts made after mid last year

[Istas]

I'd say they're practically required...

I got a Kerbal to do a flyby of Duna and return on only 3 stages. If only three stages are allowed, then that's how it is. I just want to know.

[Istas]

Clarification request: basic jet or turbojet?

The OP has a pic of a turbojet on their example, so I'm assuming they're allowed.

[Jack wooster]

Aye, it's a turbojet, as long as the jet engine and the Solid get you into space, then put what you like on top of it. Soranno maybe right about ion drives, once you are up there with a bit of Xenon in your tanks the potentional range is enormous. I've got a lander to Dunna, a sample return mission is on it's way to Ike, and Jeb is on his way to Laythe, don't know if he'll make it though!

[soranno]

I`ve abandoned the ions, and went for a new design. Manage to break Kerbin SOI on every launch now, only I don`t want to haha! trying to make a mun or minmus landing. I`ll play with this some more and post a few images when I have a result

[soranno]

Finally a success! All in all a relatively straightforward minmus landing, nevermind that I was aiming for Duna. After bursting out of Kerbin`s atmosphere and to escape velocity, I found myself with a double encounter, both Mun and minmus, with the Mun sending me into an odd sort of polar collision trajectory with minmus.

On the launch pad in all her glory:

Abandoned the ion plan in favour of an ANT powered probe! Just like on my Duna glider design, it turned out much preferable to trying to go ion powered.

Second stage spent, and at escape velocity. You`ll see I`m running engineer, but well I figure if you`Re allowing Mechjeb then it should be a given that engineer is fine.

Into low minmus orbit, and looking for a landing site, this large peak caught my eye

Touch down

My biggest concern at this stage, was the very real possibility (in fact I was just sure) that deadly reentry was going to make it impossible for me to land this thing back on kerbin.. as I was never going to weight it down with a heat shield.. nevertheless I started down into the atmosphere, using what fuel I had left to try and lower velocity while keeping my entry angle shallow.

and perhaps miraculously, one leg and one solar panel lighter, 2 days and 5 hours after take off parachutes deploy

After spending so much time (sooo much time) playing around with giant ships and stations etc, I have had more fun flying this little thing than anything else in kerbal for quite some time. You have my thanks for putting up this challenge!

Now to try again for Duna, and then to Gilly!!!

Full gallery of this trip has a few additional images here: http://imgur.com/a/e6rRV

Edited April 28, 2013 by soranno

[occar]

Woops, mistake post.

Edited April 28, 2013 by occar

[planetx]

Okay gang, I made it to the Mun and back manned by Jeb! Full gallery with all the proof here: http://imgur.com/a/xiBHK

Achieved 100km apoapsis, documented. Accidentally ignited the 3rd stage engine before grabbing proof of my final 130km apoapsis, so I'm submitting my entry as a 100km apoapsis. I put a Jeb-manned munar lander into space with my 1 stage of 1 jet engine and my 1 stage of 1 RT-10 SRB.

Only mod used was Mechjeb 2, and boy did I need that. I BARELY got off the ground with the 1 jet engine, and my fuel window was so tight that without the precision of Mechjeb I doubt I could have done it.

[soranno]

Back again for take 2, and the mission to Duna!

Maneuvers complete, on course for Duna aerobrake.

Would go straight into a double dip entry off the one aerobrake, and so use no fuel.

The approach had been going so well.. Ike decided to .. step in as it were

But with a quick correction we were back on course for an 11.6km periapsis... however, Ike wasn`t quite finished.

Damnit Ike get out of the way, nobody likes you

Following a parachute assisted landing, the probe sleeps on Duna.. perhaps dreaming of electric probe-sheep..

Day 205 of the mission, and the one opportunity this little probe had at making a return to Kerbin. As the sun set, his little engine spurted to life, and towards the stars we crawled...

Alas, it was not to be, and at 36km our fuel is spent.

Farewell sweet prince-probe, sorry my burn for Duna encounter was so horribly in-efficient

Full gallery here: http://imgur.com/a/LHtku

[occar]

This challenge appears hard at first glance, but it's surprising how easy it is to leave Kerbin orbit just with 1 jet and 1 small SRB. I didn't land anywhere, but even my first attempt put me intercepting with Duna's orbit without even trying. Of course, that's with only a sputnik probe on top, but the jets are so efficient, you could put a lot more up there and build up ~2km/s in atmosphere no problem, then have the SRB, then whatever you want to put on top.

[tavert]

I've got a manned mission heading to Dres. Started at 9.56t on the pad, and with lots of intakes and MechJeb2 controlling the jet throttle perfectly, I got up to a 45 x 158 km unstable orbit before even using the SRB. Timing your takeoff properly means there's no need to stabilize the orbit before firing the SRB to get wherever you're going. I got almost 1400 m/s delta-V from the SRB alone, it's a little less than 200 m/s more to get on a Dres encounter, and I've still got almost 3 km/s left. That should be enough to capture, land, and hopefully take back off and return to Kerbin with. I'm not sure yet, I'll post pictures after I finish up the mission.

With a probe you might even be able to get a Laythe sample return? Guessing on that, haven't actually done the design or run the delta-V numbers for the mission plan.

Edited April 29, 2013 by tavert

[planetx]

I've got a manned mission heading to Dres. Started at 9.56t on the pad, and with lots of intakes and MechJeb2 controlling the jet throttle perfectly, I got up to a 45 x 158 km unstable orbit before even using the SRB. Timing your takeoff properly means there's no need to stabilize the orbit before firing the SRB to get wherever you're going. I got almost 1400 m/s delta-V from the SRB alone, it's a little less than 200 m/s more to get on a Dres encounter, and I've still got almost 3 km/s left. That should be enough to capture, land, and hopefully take back off and return to Kerbin with. I'm not sure yet, I'll post pictures after I finish up the mission.

I'd love to see a picture of your craft. My entry for this challege (refer to link in my earlier post) only allowed me to put my 1-man capsule to 100km apoapsis AFTER the RT-10 fired, so my 3k delta-v was used for Mun operations. Succesful, but the jet engine and srb barely did it for me. I'm interested to see how you pulled it off.

[tavert]

Okay, since you asked (and I posted before finishing the mission), here are pictures of what I've done so far: http://imgur.com/a/RIVua#0

So superficially it looks similar to your craft, but several key differences:

- To fuel the jet I used a Mk2-to-size-1 adapter and 2 round-8 toroidal tanks. This gives 100 liters of liquid fuel for 0.772t mass. The Mk1 tank that you used is small and conveniently cylindrical, but it is has a worse mass fraction than the aircraft parts. It's heavier and carries less fuel than the Mk2 fuselage (or a pair of adapters).

- I have less fuel in my final stage, and less mass throughout. Your craft is so heavy (relative to what 1 jet can lift at zero speed) that a significant amount of your jet fuel fights against gravity losses, and you spend more time at low altitudes where the jet's not as efficient. I also cut down on mass as much as possible by skipping the parachute (so even if I make it back to Kerbin I'll still need to have enough fuel left for powered landing. It should only need ~200 m/s for that, and cutting out the mass of the parachute gives me some of that for free), using the tiny struts to mount my intakes instead of the larger girders, 2 tiny decouplers instead of 3 medium ones, and the aircraft landing gear (which are currently massless in flight, and can stand harder landings too) instead of legs.

- Ridiculously many intakes, so the jet alone gets me past orbital speeds in the high atmosphere. I basically circularize an "orbit" at roughly 40 km altitude, then keep going even faster to get the apoapsis up into space.

Edited April 29, 2013 by tavert

[occar]

I'd love to see a picture of your craft. My entry for this challege (refer to link in my earlier post) only allowed me to put my 1-man capsule to 100km apoapsis AFTER the RT-10 fired, so my 3k delta-v was used for Mun operations. Succesful, but the jet engine and srb barely did it for me. I'm interested to see how you pulled it off.

How fast did you get in atmosphere with your jet engine? If you didn't get upwards of 2km/s velocity with it, you're losing a massive amount of potential delta V due to inefficient launching.

Jet launching is much, much different than rocket launching. You need to stay in the low 30's of km altitude until you get your jet's top speed, then start climbing again, slowly, as long as you can while avoiding flameout and eventually firing the rocket once you are as high and as fast as you can go. Keep in mind that a good jet can actually get in to an orbit (though air braking will cause it to not actually work).

My best on a jet is an apoapsis of 250km and a periapsis of 40km with a speed of around 2300 m/s at the periapsis. We're talking only providing like .5kN of thrust with the jet engine in such thin atmosphere, but you can slowly work your way up, and just barely provide thrust that you eventually reach an equilibrium, but it's a hassle to fly like that. (Jet + Ion drives makes for a really easy orbiter with no oxidizer).

Edited April 29, 2013 by occar

[planetx]

How fast did you get in atmosphere with your jet engine? If you didn't get upwards of 2km/s velocity with it, you're losing a massive amount of potential delta V due to inefficient launching.

I only got to 900 m/s. My Jet engine TWR at launch was 2.02, and because the jet engine at take-off only produces 112kn thrust and mechjeb TWR is based on the maximum jet engine thrust (220 or something like that) that means my TWR was effectively 1.01.

It took a bit more than half my fuel to reach 10km before I turned over and adjusted my angle of attack to create horizontal velocity, then I only got to 300 m/s with about 25% fuel remaining. By the time I got to 900 m/s I was out of fuel and had to kick in stage 2.

I tried different ascent profiles, but the above profile gave me the best speed before I ran out of fuel. I tried adding more liquid fuel but then I couldn't get off the ground, because my Munar lander weighed so much. I tried paring down my lander size but then I didn't have enough dV to make it to Mun and back.