farmerben
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Posts posted by farmerben
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Mono has density 4kg per unit, where LFO is 5kg/unit. So thats like an ISP of 312.
This is much better than the Twitch engine.
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I overlooked the puff engines for a long time. Now I'm working on a mining vessel with xenon engines. My mining vessel doesn't want to carry lots of fuel and oxidizer tanks, these can dock during refueling. Monopropellant tanks are a better deal in terms of weight and usability. It occurs to me that puff engines could provide the kick to move asteroids or takeoff from Minimus when more thrust is required.
In early testing I just blow through all my Mono propellant.
Does anybody the puff engines? How do you use them? Pictures please
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This topic deserves its own thread. How about rail launching the first stage of a spacecraft.
http://www.g2mil.com/skyramp.htm
This is the most thorough analysis of the topic I have seen. It appears to be the work of amateurs rather than bureaucracies. The claims appear reasonable to me. I wonder if anybody else sees flaws in their analysis.
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The USAF has demonstrated that steel tracks and wheels perform just fine at nearly Mach 8.
There is a moment at 12:27 in this video (F III ejection module test) worth watching. A stubby aircraft detaches from the sled and uses off axis engines to climb.
A track ramped vertically is better than a horizontal one except when it comes to runway length. I think we can get a 10 degree angle straight track in the Andes about 30km long capable of accelerating humans to Mach 5. (conservative estimates, more is possible).
A tunnel launch system with electric magnetic and gas pressure propulsion is obviously awesome. But it appears that a completely ordinary railroad on the surface can handle this job, provided it is tuned to precise tolerances. The capital cost of the latter is fairly trivial.
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The saying that fuel is cheap but staging is expensive is less true with a rail launch system.
The problem with rail launch on Earth is that atmospheric drag kills you. We need something that can cruise at a steady hyper-sonic speed while gaining elevation. Save that precious dV for when the atmospheric drag is minimal.
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Looks like the Gnom was a solid fuel booster which went from Isp = 180s to Isp =550. Doesn't say if they make the air fuel rich for afterburner, probably not.
NASA thinks they need massive air intakes... they must be doing it wrong. The key is to use atmospheric oxygen without depending on it to maintain a primary combustion point.
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Maybe I shouldn't have posted this as a challenge.
Mostly interested in what is the lightest, cheapest, lowest tech solution.
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We need a full big orange tank with a docking port for a single refueling mission. Target altitude 70-250km
Bonus: Use the fueling vehicle for all docking maneuvers.
Bonus: de orbit all parts
Prizes:
Lowest part count
Lowest on the tech tree
Lowest funds at liftoff
Lowest funds for entire mission (spacecraft recovered).
Most absurd
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New engine:
A small circular aerospike engine is surrounded by an extra pulse jet nozzle. The outer nozzle is just far away enough to stay out of direct flame of the aerospike. Aerospike thrust will keep air moving in the tube so its not a true pulsejet. Extendable length air intakes can adjust the position of shock cones so intake air has a max compression shock at a precise location just below the truncation of the aerospike. Hydrocarbon fuel is dumped in at the truncation of the aerospike, it combusts and exerts extra pressure against the flat of the spike and the outer nozzle. Functions to some degree at high altitude, because atmospheric oxygen is not required to maintain combustion temp.
... This engine probably stays fixed to the aerospike, no staging.
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And we only need about 30m/s on water before we can pitch up and stand on the panther
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There we go. I added a wing type E and a strake below my engine to survive splashdown. Works fine now.
It took a few tries to get this right. Most of the MK2 parts will survive spashdown at 40m/s. The pitch planes at 50% have enough authority to go nose up or nose down rapidly at extremely low airspeed.
The aircraft parts mod has some MK2 parts with more height, very useful for water takeoff.
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I landed a 6ton craft in the smallest lake, but my panther engine broke off and I was unable to take off again. Probably could have.
Used aircraft mods and modified mk2 parts to splashdown. Elevons as canards and tail planes enabled it to flip straight up to straight down in 50m with no minimum controllable speed.(having trouble with screenshots, its on my screen and quicksaved right now).
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Describe what you could do with these engines....
The inventor built helicopters with the engines on the rotor tips and intakes along the blades.
My plan is to rail launch out of the Andes at mach 5. Use ramjets to accelerate across the Atlantic, and detach to land the stage near Kilamanjaro. Launch a final stage into orbit on oxidizing engines.
https://en.wikipedia.org/wiki/Gluhareff_Pressure_Jet
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When I used to dock spacecraft in staging mode I would see a readout in yellow telling me distance to target. This indicator disappeared. I'd like to turn it back on. How?
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These issues will be no brainers to experienced players, but I'm a newbie like you who just started landing on Duna and Eve a few weeks ago.
Communications networks and electrical systems can be the Achilles heel of these missions. Solar panels are much weaker on Duna. The mid-tier dish antennas are not always good enough. And communications can consume way more electric charge than I took into account.
The science probes I sent to Duna and Eve were only partially successful. I couldn't transmit all the science back without running out of charge. The workaround was to transmit results one by one. For example, right clicking the thermometer and transmitting just thermometer data was successful... then waiting for charge to build up and doing the barometer, etc. The atmospheric spectrometer instrument seems to have the largest data packets and I simply could not transmit that with the amount of electric charge I had.
I've got a Jool flyby probe with plenty of power and some mid-tier dish antennas (the flip down ones). The antennas are not good enough. I've got plenty of comsats near Kerbin, so the issue is range not line of sight.
The solutions are fairly obvious. Had I been going to minimus or to look for asteroids in solar orbit, the technology onboard was adequate. Going to other planets requires a lot more communications power. Hope this helps.
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I've been trying to minimize orbital debris by dropping my stages before PE reaches 70km, but it's not working. In the tracking station I discovered I had 99 pieces of debris most of which had a PE between 50-70km. I watched from the tracking station and the orbits did not change, several pieces had been orbiting for more than 5 years. I clicked on fly for a few pieces and they burned up or crashed as expected, others I just terminated. Also I was surprised to find very few pieces on Kerbin surface, because I sometimes put parachutes on stages.
I believe there is a mod to help with this, but I can't find it just now. Help please.
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Is there a guide a air intakes for KSP?
It seems that the biggest difference between the different intake parts is "base effective speed" , what does that mean?
When I right click on air breathing engines I almost always see 100% of propulsion requirements met, or the engines cut off completely due to lack of air. I never see 90% of propulsion requirements met, so even through trial and error I'm unable to figure out the minimum amount of air intake I need. I do notice thrust of my engines varies with speed and altitude, but I don't know how to apply this information to decide whether more intakes, fewer intakes, or different intakes would improve performance.
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6 hours ago, Hesp said:
Making some assumptions based on Falcon 9 launch profiles, the rocket velocity at 20km altitude is around Mach 2 / 2.5
It's safe to assume that most of the air augmentation will happen below that altitude, so exotic intakes (J58 variable geometry spike) are not needed. A proper designed diverterless supersonic intake could suffice.
That is a good starting point. But an air augmented engine will have a unique flight profile. More research and modelling would be needed to determine exactly what that is.
I would guess that in the low atmosphere one would want to go a bit slower. We would want our thrust bonus to exceed the gravity losses of a slower climb, and otherwise stay slow to reduce drag.In the upper atmosphere (~20-70km) we would want to pitch more horizontal and throttle up. This maneuver would happen later than a scramjet design, but earlier than a pure rocket.
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That is a good starting point. But an air augmented engine will have a unique flight profile. More research and modelling would be needed to determine exactly what that is.
I would guess that in the low atmosphere one would want to go a bit slower. We would want our thrust bonus to exceed the gravity losses of a slower climb, and otherwise stay slow to reduce drag.In the upper atmosphere (~20-70km) we would want to pitch more horizontal and throttle up. This maneuver would happen later than a scramjet design, but earlier than a pure rocket.
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I agree with all those concerns. I don't know if the complexity, gimbaling, and cooling considerations can be adequately solved.
But this idea of a simple skirt around the rocket engines seems to have a lot of merit compared to side mounted ramjet boosters. It should improve efficiency across all altitudes and airspeeds. The P51 Mustang channeled bypass air around its exhaust pipe and got a noticeable increase in thrust at 500mph. The drag created by air intakes must be contrasted with the drag created where a cylindrical fuel tank ends a meter or more before the exhaust plume begins with a conventional rocket. Combustion is difficult to achieve at high altitudes and airspeeds, but heating bypass air works basically the same way. Fuel may be cheap, but good fuel tanks are not. The question is how much a skirt would cost in terms of weight and money compared to the fuel tanks you would need without them.
If a relatively thin titanium alloy skirt could withstand the temperatures, without active cooling, it might be a better deal.
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Thanks Wjolcz! It is useful to know there is a name for it and somebody thought of it. It appears few tests have been done with the concept.
I suspected the biggest problem would be vibration or cooling considerations of the primary rocket engine, or overheating issues with any practical skirt. The problem of large sized air intakes and extra weight does not seem all that serious to me. If it is only used with the first stage for the first minute or two and then detatched, and is reusable, then the weight does not seem like a problem. We should in fact save a lot of weight in fuel for the first stage.
All the NASA designs I have seen involving ramjets are for SSTO's. In that context I understand why the weight might not be worth it. But in a multistage design this is not an issue.... you detach the parts when you run out of atmosphere. If the parts are reusable and do not require active cooling it seems like a bargain.
It also seems to me that Whiplash style air ducts would be stable, in that a change in pitch will increase the relative airflow on the side the vessel is pitching into.
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Take a close look at the Whiplash engine in KSP. The engine has a skirt with radial air intakes to mix bypass air with the exhaust plume. The bypass air is not fed directly into the combustion chamber, but mixed with the exhaust. The heating of the bypass air inside the skirt increases thrust. If the radial air intakes had ramps to control input air, an afterburner could be used, but increased thrust is possible even without an afterburner.
My question is: Is it practical to combine this type of bypass air skirt with a regular rocket engine?
puff engines
in KSP1 Gameplay Questions and Tutorials
Posted
This is an asteroid miner I'm working on. With 6 xenon engines TWR =.1, with 4 puff TWR = .75 and the Mono is good for about 900 dV. I have more solar panel and batteries than I actually need.
All the prototypes for this vessel had more xenon engines (as many as 64), but the performance was not much better and my computer could barely handle it.
What do you have that is similar? What improvements would you suggest?