mystifeid

And don't assign anything to the main throttle axis group. Use custom axis groups instead. When testing for best speed it soon becomes apparent that there is a very narrow window for optimum prop pitch. You will either need to get lucky to find this optimum setting or have switched on fine control (caps-lock). Main throttle keys do not seem to respond to the use of fine control but custom axis group keys do respond. As an example, if I takeoff and have rpm limit on the main throttle the smallest change I can make with or without fine control is 4 rpm with a sharp tap on the throttle keys. With rpm limit assigned to a custom axis group, the smallest change I can make with fine control switched on becomes on average 0.2 with the same sharp tap. With prop pitch on a custom axis group the smallest change I can make is 0.5 (or two taps to make a change of 1). Best speed is achieved within a prop pitch window of 0.5 - 1. After takeoff, reducing prop pitch will usually increase speed until a point is reached where either the speed starts to drop or the current rpm (not the rpm limit) starts to drop below 460. The value of the prop pitch at this point is worth remembering. When starting a sharp turn or a steep climb it may often be worth changing the prop pitch back to this value. Effectively you can control airspeed and power by only using the prop pitch. But you need the current rpm to drop in order to reduce prop pitch to achieve the fastest speeds. If say, in level flight, the current rpm does not start to drop and speed reduces when you reduce prop pitch from this value, you can force it by reducing the rpm limit and further reductions in prop pitch should see a marked increase in speed. At some point the current rpm will usually drop below the rpm limit. Quite often though, the current rpm will drop by itself leaving you to concentrate on finding the optimum pitch for speed. When trying to find the best settings for maximum range, only two things seem to affect fuel consumption - rpm limit and torque limit. Again it will be a benefit to be using fine control with nothing assigned to the main throttle keys. I find landing to be pretty easy. I reduce rpm limit and torque limit if for no other reason than making sure I don't run out of fuel before landing then on final approach, increase prop pitch back to 100 and drop the landing gear. Speed drops dramatically but flying in under power still provides good control. All robotic engines can have an action group key assigned to toggle the motor direction. So on touchdown, reverse the engines until stopped or nearly stopped then use another action group key to toggle prop deployment. This is much safer and much more effective than using brakes. Like @aegolius I disengage the engines in the SPH so my usual setup is something like this Action group 1 - Toggle engage engines Action group 2 - Toggle engine power (full torque on/off) Action group 3 - Toggle prop deployment Action group 5 - Toggle motor direction Custom axis group 1 - prop authority Custom axis group 2 - rpm limit Custom axis group 4 - torque limit So takeoff is as simple (after engaging SAS with the 't' key) as 1,2,3. If you want to see a hard to land plane, you can check out the landing at the end of the video below which was made for the Kerboprop Speed Challenge - which requires a landing back on the runway. And it wasn't hard. The optimum prop pitch for speed with this plane is 29.5 - note that the current rpm is only 220.7 at 298.6m/s - while the value for the prop pitch I use to maneuver is 70 and you can see me increase it back to 70 as I start the vertical climb preparatory to returning to the runway and then back to 100 just before landing.

Each planet/moon type really needs a different design and a design will really depend on how far you intend to travel around that planet/moon. Driving around close to KSC will produce a design different to one used to circumnavigate Kerbin. I was interested in the latter and also very interested in finding the best designs for speed.

Hi. I'm assuming you're using hinges. Have you tried assigning an action group key to toggle locking the hinges? Locking allows autostruts to pass through robotic parts. When unlocked, autostruts terminate at robotic parts. And when locked you might find you don't need autostruts.

I'm hoping not! I've deliberately stayed away from testing small designs and I'm hoping someone finds a way to go faster!

Unfortunately 16 'S' type blades don't fit on the small turboshaft engine without serious clipping. Even with 12 blades there's a small amount of clipping and when I tried 12 on the Arrow it went slower. So I went the other way and tried 6 blades per engine and saw the speed increase to more than 298m/s. This time best speed was achieved at low altitudes. Go figure. Adding another eight engines made absolutely no difference to the top speed but for sheer amusement, it is the 24 engine "Barbwire Canoe" in the video below. It gets down to 4m above the water and it's a pity there's no ground effect in the game. Speed run starts at 4:21 on the game clock. Speed 298.6m/s.

Looks like one of your prop blades hit the runway when you first touched down - I've seen that puff of smoke a lot of times before. Anyway, more blades then. I wonder what another 128 blades will do for me. No time now though.

With a lot of the aircraft I've tried, when torque is at 100% and current rpm at 460, the best speed I can get by reducing blade authority is usually around 230-240. Often, reducing the blade authority then automatically reduces the current rpm to 200-300 allowing further reduction in blade authority (in the video above I'm doing 291m/s with 213rpm). Sometimes though, the current rpm doesn't drop by itself and reducing the rpm limit becomes necessary to reduce blade authority for optimum speed. After having a look at the Kornier, @g00bd0g sets engines and props up differently to me so you might have to translate what is above according to your setup. Also, the 16 engine beast achieved best speeds flying beween 1500-1800m and I thought that might be the case for all aircraft but now I'm swinging the other way - you just have to find the right altitude for your particular design. And I've found that fine control (caps-lock) does not seem to affect the throttle keys but it does affect the custom axis groups. So I've stopped assigning anything to the main throttle axis group. With caps-lock on I can change, for example, the blade authority by 0.5% with a tap of a custom axis group key.

Something completely different - the flying pig Broad Arrow. Uses 16 turboshaft engines. Top speed - 291.2m/s. Craft file.

What about lowering the rpm limit so that it's still above the (reported) current rpm. Why does this lower fuel consumption? Anyway, these are still new parts and as such they are probably still works in progress.

I can't remember ever seeing the turbo shafts having insufficient airflow. I think that fuel consumption is only affected by torque limit and rpm limit. You can change these in the engine PAW (right-click window) or you can assign them to axis groups. Even though you can use the main throttle axis group I've found that when using fine control (caps-lock), the custom axis groups provide very granular control compared to the throttle keys which seems to unaffected by the use of the caps-lock key. But maybe that's just my keyboard. (Note that by default there are no key-bindings for the custom axis groups - they must be assigned in the game settings under Input -> Vessel -> Axis Actions.)

Sorry, but I liked the comparison. I'm sure you do get high frame rates with low part counts. (So do I.) If the same holds true with a rocket with 4000+ parts, I want your computer !!

10,000km/s? Yeah right. Here's what it took to get 23.5km/s from a vertical launch using stock parts. But even this type of challenge is pointless. It's extraordinarily difficult making these in a normal VAB because of the size and then it comes down to who has the most patience as the ship lurches upward at 2fps.

@Snark reported in this thread (which is worth reading for it's own sake) that locking a robotic part allowed an autostrut to pass through it. The quick test shown below using autostrut : root seems to support this. Engines attached to engine plates become Autostrut Locked : Grandparent part once they are on the launch pad.

Unfortunately it seems that lowering the rpm limit, even so that it is still above the reported current rpm, appears to have a marked effect on fuel consumption. Using a four engine plane carrying 2000 units of LF in level filight at 3000m and having only used torque and blade pitch adjustment so far: Torque Limit - 16.6% RPM Limit - 460 Current RPM - 250 Speed - 220 Prop Authority - 44 Fuel - 62.4mU/s (per engine) Subsequently reducing the RPM limit to 285 produces no effect on the speed or current rpm yet appears to lower fuel consumption to 38.7mU/s (per engine). Edit - Later had the time to watch the actual fuel consumption over the course of an in-game minute. With the RPM limit at 460 I used 15 units of fuel. Lowering the RPM limit to 285 saw the fuel used drop to 9 units. This corresponds to the fuel consumption reported by the engines - ie 0.0624 x 4 x 60 = 14.976 0.0387 x 4 x 60 = 9.288 Also, in the current configuration of this plane, I find it much easier to fly (in level flight) with a torque setting of around 25% and an RPM limit of around 300. This still gives me a fuel consumption of around 60mu/s per engine but with an extra 25m/s flying speed. Flying with minimum torque seems to produce bigger fluctuations in the current rpm and suddenly the blade pitch becomes incorrect, the speed drops, blade pitch gets further out of whack and then I'm falling out of the sky.

It wasn't your average plane but I've seen an 'old style' stock prop circumnavigate Kerbin using ec from a fuel cell with just a single dumpling of fuel. See the Dumpling challenge.

With planes it has been my experience that it is expedient to tweak torque, rpm and blade pitch separately. Initially I tried using torque in the main throttle group without touching rpm and sure, reducing torque also reduced rpm. But then I tried reducing rpm even more with a different axis group and found that I could then drastically reduce the blade authority. This had the effect of increasing speed while using less fuel. With rpm on the main throttle (or any axis group), reducing rpm has no effect on the torque limit. Anyway, I think if you are going to rely on torque reducing rpm optimally or vice versa, then you will be wasting fuel. It has just become automatic to assign axis groups for rpm, torque and blade pitch. My only experience with a quadcopter has been lifting a single stage Terrier powered rocket to a position where it could obtain Kerbin orbit. Best results were obtained by keeping rpm and torque maxed and using blade pitch to regulate (maximum) vertical speed.

No $#%#&^% tourists.

Does it matter? Put one on the main throttle (if you like) and put the other on a custom axis group. Or put them both on custom axis groups.

Are you using the biggest motors? In the test above I was launching with blade authority limit at 100% then increasing it to 101% until my speed got to about 50m/s. Decreased it to about 82% until speed got close to 130m/s then increased again, slowly, to maintain speed, sometimes to as much as 125%. Even on Kerbin it takes a long time to reverse a descent. Anyway, good luck with your endeavors!

As @OHara observed, blade pitch is important - are you adjusting the pitch as you ascend? Also, might it not be better to try to get up as quickly as possible (big motors, max torque) and release while you still have a reasonable vertical speed? This may not help you getting into orbit around Eve but... I played with getting a single stage Terrier into orbit around Kerbin. The first attempts were hitting 9000m-10000m before stalling and then they didn't have enough fuel to reach orbit. I was launching with reduced torque, rpm and blade pitch (props not blades) because the craft became unstable if it accelerated/ascended too fast. Safety first, so 20m/s up was it with me trying to increase the aforementioned torque, rpm and pitch as I went up. It was tricky. I kept adding more fuel so as to make orbit with each attempt getting closer. In the process I found that it was much easier and a heck of a lot faster to launch at maximum rpm and maximum torque, then just use blade pitch to smoothly accelerate to 140m/s up (much faster and bad things happened). I try to hold that speed for as long as possible by adjusting the prop pitch but because I am moving relatively fast, the cutoff point where the props start to become useless also comes much faster. This is the time to release and fire the rocket. The first time I made orbit I released with 0m/s vertical speed - ie I maxed out the height first - and made it into orbit with about 50m/s dV to spare. Now I am releasing with 100m/s vertical speed - although at a lower altitude - and am reaching orbit with more than 1000m/s dV left. Big difference. (Edit - with planes it doesn't matter so much but in this case I found it really, really helped to turn on caps-lock and use the fine adjustment for changing the prop pitch. One tap of the axis group keys gave about 0.5% adjustment)

I flew variants of the single engine plane pictured below for quite some time (an hour or more). I tried adding a couple of reaction wheels and I tried reducing the motor size to 30%. I tried reducing torque on takeoff. Nothing helped. Having said that, it was quite easy to takeoff and fly. By using SAS on takeoff and making one small steering adjustment I repeatedly ran the entire length of the runway before lifting off. After climbing out I turned SAS off and used trim to counteract the engine torque. Regular small input was necessary but it was not difficult or onerous. Landing deadstick was easy since I no longer had to deal with the torque. This whole thing was made a lot easier by having spent a lot of time flying a multiple engine plane which does not have any issues with torque and with which I learned to contend with settings for variable prop pitch, engine rpm and torque. Before that I had tried another single engine plane and found it very difficult.

Reducing the torque of the engine in the PAW and/or using a smaller motor may also help.

Have you assigned keys for the custom axis groups in the game settings? (Under Input -> Vessel -> Axis Actions). I use numberpad keys / and *, 8 and 9, 5 and 6, 2 and 3 for the four groups. Assigning the prop authority limit to custom axis group 1 lets me increase/decrease the prop authority by using the / and * keys. Not sure how much fuel/weight anyone else is carrying but the plane above has 880 units of LF - more than enough to get me over the ocean to the east of KSC. Previously I had just been using engine torque limit and the prop authority limit to maximize flight distance - above with the 225m/s speed, each engine was reporting fuel consumption of around 98 mU/s. So now I'm using RPM limit as well and am flying faster while using less fuel: Speed - 255m/s (+30m/s) RPM - 285 Torque - 35% Prop authority - 42% Each engine is now reporting using around 81 mU/s. That represents a significant increase in flight distance. So it's definitely worth playing with the settings.

Engine 1 - clockwise; Props - clockwise variant and deploy direction normal. Engine 2 - counter-clockwise; Props - counter-clockwise variant and deploy direction inverted. Don't forget to set the number of attachment nodes on the engines before adding the props. I found it easier to add engines to nacelles one at a time. Adding them in pairs with symmetry and then removing them from symmetry seemed to cause some strange things to happen. For example - reverting to the hangar would sometimes see the engines back in symmetry again. With SAS engaged, this four engine plane takes off in a gentle climb with no input required (hands free). No roll or yaw input required to maintain level flight. Cruises at 225m/s at 3000m with prop authority at 72% and engine torque at 25% The idea was to take off and fly directly east over the ocean until the next land mass was reached. And it made it with a reasonable amount of fuel to spare. I figured if a plane-building novice like me could do it in a reasonable time frame then the new parts were going to be ok.

When I lower the turboshaft torque to 25% the rpm drops from 460 to 415 but visually the props look like they are hardly spinning.