New Electric Atmospheric Engine

[specialopsdave]

Perhaps we could have an electric propeller added? Perhaps it could be Tiny, with 10kN of thrust, requiring only EC? or a stack version, using IntakeAir and EC? It'd be hard to fly with, but possible with large enough wings.

[HazelPine]

I support this idea a whole lot. Maybe something like this:

Spoiler

But ya know, really teeny-tiny!

Edited July 22, 2016 by Pine

[OrbitalBuzzsaw]

Stock KAX!

[SpannerMonkey(smce)]

 

18 minutes ago, Pine said:

I support this idea a whole lot. Maybe something like this:

  Reveal hidden contents

But ya know, really teeny-tiny!

That's a marine drive not an aircraft propellor ( and you can get something very like those in mods Large Boat Parts and SM Marine )

I think you'd prefer something like

Spoiler

 

[HazelPine]

@SpannerMonkey(smce), That's what I meant! I just googled "radial eletric propeller" and picked the first thing with the shape I was looking for.

[qzgy]

Squad probably already has these engines at their Offices. Probably called Fans instead

[Pds314]

1 hour ago, qzgy said:

Squad probably already has these engines at their Offices. Probably called Fans instead

Fans do different things than props. Fans push a large volume of air, whilst props push a large momentum of air. The optimal fan design is not necessarily the optimal prop design.

Similarly, wind turbines care about the incoming power of air, not the incoming momentum or mass flow.

So for example, 2 Fans, both push an equal mass/second of air, niether is better at cooling, but the smaller fan will consume more power and have more thrust.

Two props, both with the same thrust. The smaller one will be a worse fan and consume more power.

Two wind turbines both with the same power at dissimilar wind speeds, the smaller one will have less drag and less airflow.

Edited July 22, 2016 by Pds314

[KerikBalm]

frequently asked for.. easily modded

Part rescale:

and other simple changes made by text editing (as with the rescale)

I would like something stock though....

[pandaman]

Yes, as @KerikBalm said, frequently asked for.  Not a game breaker or massive priority fo me, but I would welcome electric props in stock too.

[XB-70A]

Well the choice of an electric ducted fan, it will be futuristic looking for sure, should not be the most logic for an efficient engine. A slow turning propeller with a wider diameter should be a better choice in most of the situations. No doubts that some of our today's project, like the E-Fan, will give us new opportunities in some sectors but it will not be before a certain time, all of the other electric aircraft projects are based on propellers. Just like what happen with the Fenestron or NOTAR, even 40 years after their apparition most of the choppers keep the traditional, more efficient, tail rotors.

Or we could start with an electrical driven engine with propellers in the tech tree to end with e-ducted fans?

[KerikBalm]

1 hour ago, XB-70A said:

should not be the most logic for an efficient engine. A slow turning propeller with a wider diameter should be a better choice in most of the situations.

Actually, ducted fans are more efficient for a prop of the same diameter.

https://en.wikipedia.org/wiki/Ducted_fan

Quote

Ducted fans are favored in VTOL aircraft such as the Lockheed Martin F-35 Lightning II, and other low-speed designs such as hovercraft for their higher thrust-to-weight ratio.

In some cases, a shrouded rotor can be 94% more efficient than an open rotor. The improved performance is mainly because the outward flow is less contracted and thus carries more kinetic energy. ....

By reducing propeller blade tip losses, the ducted fan is more efficient in producing thrust than a conventional propeller of similar diameter, especially at low speed and high static thrust level (airships, hovercraft).

The thing is, its more efficient to push 10 kg of air at 1 m/s than 1 kg of air at 10 m/s, even though they both produce the same amount of thrust. This is because KE = 1/2 mv^2

So a propellor of greater diameter can be more efficient by moving a larger mass of air at slower velocity.

However... while they are much more efficient at producing static thrust, at cruise speed the difference isn't so great and the weight and mass of the duct offsets whatever efficiencies they gain. Thats why you see them on blimps and VTOL designs which need the low speed high TWR.

However, they seem to get an efficiency advantage again as you start going close to mach 1, which is why you see turbofans instead of turboprops on airlines which cruise at > mach 0.8

Also, the tight tolerances for clearance between the fan blades and the shroud make it more expensive.

I think a prop in general would be better for cruising around at low mach, but it seems ducted fans get better static TWR and high mach efficiency

 

Edited July 22, 2016 by KerikBalm

[SpannerMonkey(smce)]

Hi all it turns out after getting a tip off and looking through the API there is already an electric motor of sorts in the game and not used, I've tested it and sadly although you can get a gui to display with power slider, drive, reverse,  park and link to throttle options, the module doesn't work,  The modules listed are JointMotor and JointMotorTest. After checking the error in the log and going on a search through unity bugs I've a feeling that the only reason it doesn't work is because of a unity animation bug namely http://answers.unity3d.com/questions/1120170/cant-rotate-gameobject-with-animation-in-unity-53.html

If you want to check it out see link below (I'll grab a screeny in a bit of the parts) Probably wont mean much to non modders, but it proves it exists

http://docuwiki-kspapi.rhcloud.com/#/classes/ModuleJointMotorTest

And at one time there was a mod made that included them (i have it if anyone is interested)

 

[XB-70A]

Actually, ducted fans are more efficient for a prop of the same diameter.

 

Sorry I went in a bit too fast as usual and as American/English is not my birth language some bad short-cuts are taken often...

 

No doubts about the ducted-fan efficience compared to the slow-turning propeller, I was staying on the comparison between the same class of aircraft and when those are powered by a thermic or electric engine, as the topic was about a new electric propulsion system.

Like for the Airbus E-Fan 1.0, even if she's just a demonstrator of what should be the 2.0 production variant, her cruise and max-speed (around 120 its at full throttle) are around the worst place for the fan (of a really small diameter), but much more the actual Li-ion batteries technology onboard does not offer enough autonomy and kw for their weight and the place they took in the cell (without counting that once you reach around 20% of the battery charge the loss of charge should be faster to 0 than during 50 to 20).

Here is why I would go for a technical tree starting with small twin to four bladed electric engine to power a small aircraft in a multi-engines configuration and ending with ducted fans and an anticipation of what the next gen batteries, smaller and with a greater charge, should be.

 

I've probably made other mistakes and confusion while translating again... sorry in advance if it's the case.

[Wjolcz]

Electric props are pretty cool, but ducted fans look even better.

I totally agree it should be a stock thing, though it should have really poor thrust and eat EC like crazy.

[specialopsdave]

Wow! This thread got a GREAT response! I do agree with your ideal designs with the radials being fans, but maybe the inline could be like this:

The parts would be the same size as the Juno Basic Jet, but with half the thrust (in return for a theoretically infinite specific impulse).

Edited July 28, 2016 by specialopsdave

[Wjolcz]

4 minutes ago, specialopsdave said:

The parts would be the same size as the Juno Basic Jet, but with half the thrust (in return for an infinite specific impulse).

Half the Juno thrust is a bit too much IMO. Me thinks it should be 5kN at best.

It would still be comparable to the first jet engine to fly, but it's KSP. It doesn't have to be that accurate.

Edited July 22, 2016 by Veeltch

[specialopsdave]

Just now, Veeltch said:

Half the Juno thrust is a bit too much IMO. Me thinks it should be 5kN at best.

A quarter? Hmm... Maybe we can have all sorts of variants, like the initial being 5kN, and as you unlock more of the Tech Tree, you can unlock more all the way to a 1.25m part with 30kN (Quarter that of Wheesley).

[KerikBalm]

I would prefer a prop and a ducted fan, with the ducted fan having a smaller diameter than the prop. Maybe just props.

But for that little mod I did, the only stock thing I could usethat looked remotely like what I wanted was the goliath turbofan - so thats what I used. Also, the goliath rescale does almost nothing to memory use - its just 1 additional small text file, and some additional lines in another text file.

Now that I've got a new computer, maybe I'll think about some mods that add new models and textures

Of course, a major purpose of these electric fans is to have a way to efficiently move around a world's surface faster than you could with a rover. With a mod like OPM, electric power can be very hard to come by when there's a thick atmosphere and its far from the sun. Heck even the atmosphere of Eve blocks most of the solar power. So I think we could have a related class of LF+O consuming engines. Sure fuel cells + an electric propulsion system could work, but I went a little further into engines that directly burn LF+O to turn fan blades as in a gas turbine, or just to heat an expand air as additional reaction mass (ie jet thrust from rocket power).

I modded myself a number of "airbreathing" engines for use on duna/eve/tekto. - Only 1 is the electric fan seen in my screenshots. The others are turbo-rockets and ramrockets.

So my little mod set:

Spoiler

E-125 “Rotor” Electric Fan - rescaled goliath 1.25m - uses same atm curve as the goliath, 1 ton, 20 kN max thrust. The velocity curve is shifted to have a sharper decrease in supersonic thrust. Uses quite a bit of electric charge but can be supplied by a fuel cell array, or sufficient solar panels at duna. - relatively easy to cruise under solar power on kerbin. Duna- its rather hard and I instead go for shorter flights before recharging but there are some designs and throttle settings where it can hang in the air at low altitude around mid-day

TR-21X “Hera” Turbo-Rocket Engine - Juno model but thinking of making it a 0.625m wheesely. Mass 0.3 Thrust 22 kN. Same atm and thrust curve as the Juno. Consumes LF and O2, 2880 Isp (ie the juno's 3200 * 0.9 / (0.9 + 1.1) so that the LF consumption rate is the same but now O2 is consumed as well)

TR-405 "Puma" Dual-mode TurboRocket - The panther made into a turborocket that consumes LF and O2, mass increased from, 1.2 to 1.8 to represent the O2 injection systems, dual mode as before. 1800/4000 Isp afterburning/non-afterburning

TR-90X “Mephisto” TurboRocket Engine - Goliath made to consume LF and O2. Mass increased to 5 tons, Isp decreased to 5500 Isp (at the moment, I haven't compared this to the effective Isp of the electric fan running on fuel cells)

RR-X4 “Challenger” RamRocket Engine - the most complicated one to use. I initial called it a "turbo-ramrocket" since we have turbo-ramjets, but I've since changed it to be more restrictive. It has two engine modules. 2.5 tons, uses the Turboramjet model. It would be the closest equivalent to the Rapier

#1 Is just a rather poor rocket engine. 120 kN and 300 vacuum Isp. 280 SL level Isp, 230 Eve sea level Isp. This is used to provide static thrust and also thrust in space. It has an atmospheric mode that will automatically reduce thrust at higher machs which is when the player will want to be using the second engine module.

#2 is the Ramrocket engine. In principle, this is the same rocket engine - justthat when there is sufficient airflow the rocket of #1 is used to heat and compress the incoming air to produce ramjet thrust. This mode produces zero thrust below mach 0.3, but otherwise quicklymatches the thrust curve of the rapier engine - except it uses a lot more fuel than the air breathing rapier: 1440 Isp

If this was the only engine on a vessel, the rocket at ~280 Isp needs to be used to accelerate to mach 0.3 where the ramjet effect can kick in, and then would again be used in space to circularize. - or combine it with one of the turbo rockets like the Puma so you don't need to accelerate to mach 0.3 at a mere 280 Isp.

 

Edited July 28, 2016 by KerikBalm

[specialopsdave]

Spoiler

On ‎7‎/‎23‎/‎2016 at 2:22 AM, KerikBalm said:

I would prefer a prop and a ducted fan, with the ducted fan having a smaller diameter than the prop. Maybe just props.

But for that little mod I did, the only stock thing I could usethat looked remotely like what I wanted was the goliath turbofan - so thats what I used.

Now that I've got a new computer, maybe I'll think about some mods that add new models and textures - but the goliath rescale does almost nothing to memory use - its just 1 additional small text file, and some additional lines in another text file.

 

Of course, a major purpose of these electric fans is to have a way to efficiently move around a world's surface faster than you could with a rover. And with a mod like OPM, electric power can be very hard to come by when there's a thick atmosphere and its far from the sun. Heck even of Eve the atmosphere blocks most of the solar power. So I think we could have a related class of LF/O consuming engines. Sure fuel cells + an electric propulsion system could work, but I went a little further into enginer that directly burn LF+O to turn fan blades as in a gas turbine, or just to heat an expand air as additional reaction mass (ie jet thrust from rocket power)

I modded myself a number of "airbreathing" engines for use on duna/eve/tekto. - Only 1 is the electric fan seen in my screenshots. The others are turbo-rockets and ramrockets.

So my little mod set:

E-125 “Rotor” Electric Fan - rescaled goliath 1.25m - uses same atm curve as the goliath, 1 ton, 20 kN max thrust. The velocity curve is shifted to have a sharper decrease in supersonic thrust. Uses quite a bit of electric charge but can be supplied by a fuel cell array, or sufficient solar panels at duna. - relatively easy to cruise under solar power on kerbin. Duna- its rather hard and I instead go for shorter flights before recharging but there are some designs and throttle settings where it can hang in the air at low altitude around mid-day

TR-21X “Hera” Turbo-Rocket Engine - Juno model but thinking of making it a 0.625m wheesely. Mass 0.3 Thrust 22 kN. Same atm and thrust curve as the Juno. Consumes LF and O2, 2880 Isp (ie the juno's 3200 * 0.9 / (0.9 + 1.1) so that the LF consumption rate is the same but now O2 is consumed as well)

TR-405 "Puma" Dual-mode TurboRocket - The panther made into a turborocket that consumes LF and O2, mass increased from, 1.2 to 1.8 to represent the O2 injection systems, dual mode as before. 1800/4000 Isp afterburning/non-afterburning

TR-90X “Mephisto” TurboRocket Engine - Goliath made to consume LF and O2. Mass increased to 5 tons, Isp decreased to 5500 Isp (at the moment, I haven't compared this to the effective Isp of the electric fan running on fuel cells)

RR-X4 “Challenger” RamRocket Engine - the most complicated one to use. I initial called it a "turbo-ramrocket" since we have turbo-ramjets, but I've since changed it to be more restrictive. It has two engine modules. 2.5 tons, uses the Turboramjet model. It would be the closest equivalent to the Rapier

#1 Is just a rather poor rocket engine. 120 kN and 300 vacuum Isp. 280 SL level Isp, 230 Eve sea level Isp. This is used to provide static thrust and also thrust in space. It has an atmospheric mode that will automatically reduce thrust at higher machs which is when the player will want to be using the second engine module.

#2 is the Ramrocket engine. In principle, this is the same rocket engine - justthat when there is sufficient airflow the rocket of #1 is used to heat and compress the incoming air to produce ramjet thrust. This mode produces zero thrust below mach 0.3, but otherwise quicklymatches the thrust curve of the rapier engine - except it uses a lot more fuel than the air breathing rapier: 1440 Isp

If this was the only engine on a vessel, the rocket at ~280 Isp needs to be used to accelerate to mach 0.3 where the ramjet effect can kick in, and then would again be used in space to circularize. - or combine it with one of the turbo rockets like the Puma so you don't need to accelerate to mach 0.3 at a mere 280 Isp.

 

 

You could've put most of that in a spoiler   I do agree, along with electroprops, LFO atmospheric engines would be GREAT, but as for what you're saying about the power issue, one could use RTGs, or use lots of surface-mount solar panels.

[KerikBalm]

Well, as you see in the images of the electric fan I made... I do use lots of surface mount solar panels.

Solar at Jool produces 1/25th the power... flying on laythe without a fuel consuming engine would require 25x more power than on kerbin. If the engine consumes so little power that it flies fine on laythe under solar power... then the electric engine would be overpowered on kerbin. This gets even worse if you use a mod like OPM and try to fly on solar at tekto (clouds + greater distance = forget it), or on thatmo (you need a gigantor to supply a small probe core out there!)

RTGs don't produce much pwer per unit mass, and they're really expensive... the power to mass ratio may be too low for an engine that would be balanced for solar outputs closer in, and in career, one may find it easier to use ISRU and run other things on fuel cells or engines that directly burn LF+O. So I think LF+O atmospheric engines should be added alongside electric engines.

[Wjolcz]

1 hour ago, KerikBalm said:

So I think LF+O atmospheric engines should be added alongside electric engines.

LF+O propeller engines sound a bit like a waste of fuel, but I would love to see air-augmented rockets in stock. They are more realistic than the RAPIER (AKA SABRE) engine (simply because they already flew).

[KerikBalm]

why are they a waste? It wouldn't be so much different from running a fuel cell an an electric motor. Kerbin and Laythe aren't the only places people want to fly.... Jool, Eve, and Duna should also be considered... although not so much Jool because of the low MW of the atmosphere, the lack of any biomes to traverse in the "flying low" condition, and the nigh impossibility of returning to orbit from the lower atmosphere.

Solar works poorly at the surface of Eve due to the thick atmosphere. Solar works ... only OK at Duna due to its distance from the sun. Solar power output is only 43% of the power at kerbin... but the thin atmosphere blocks less, and less power is required to fly in theory because of the low gravity (0.3 G).

I don't have the numbers for eve... but I recall solar power was really bad at sea level. In low orbit of eve vs kerbin, you've got 91% more power output. Gravity is 70% stronger. If the atmosphere blocks 3/4th of the solar power at low elevations, its going to be rather hard to have enough power, assuming you balance the electric motor propulsion so that, at Kerbin, with a large wing covered by solar panels you are able to maintain flight.

If we get an electric motor, I expect it to be balanced such that our designs will have to look something like this, but not as extreme (this is KSP after all):

Which is how I tried to balance the electric propulsion I made (note the deign in my earlier screenshots).

That leaves power at low altitude on Eve, or any dsitnation father than duna (where the power production vs power required due to lower gravity ratio is similar to kerbin) unable to be supplied by solar. RTG power output is and should be too low in comparison. Unless they add a nuclear reactor part, that means the electric prop becomes a defacto LF+O prop as people use fuel cells to power it. It also allows flying around near the terminator.

If we have hybrid electric+ fuel cells at one end, and air augmented rockets at the other end, who not add LF+O using turborockets in the middle as well?