Azimech

[Stock Helicopters & Turboprops] 1.4 problems

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Version 0.1. I'm not sure what to do with this. Would anyone want or need such a plane?

But ... it is the first modern 4 engined stock turboprop in KSP!

6TPY0G5.png

Hey! This shouldn't be happening!

5lY8FTX.png

Ohw ... forgot the cage struts on that engine. Still ... perfectly flyable with the other three.

"Alpha Sierra Sierra Whiskey India Papa Echo! RTB immediately!"

VVoidZj.png

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I'll be using the Bf engines for the P38 :-)

They're a bit different, and could be compared with the V12, where the standard engines are more like radials.

- - - Updated - - -

lkxORQD.png

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Failed experiment:

cL31EHv.png

kzXTyL8.png

All power is being consumed by internal drag, above 11 rad/s. It's got some drag spikes too, sometimes costing 2-3 rad/s for a moment.

Too bad, because it's VERY strong and VERY reliable. Good looks too! Maybe useful as a wheel bearing for a tank? Lots of parts though, and a Bravo India Tango Charlie Hotel to build.

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@Azimech - if you're a bit patient, we'll have small landing gear wheels and fairings for this kind of job in 1.0 :)

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Patience is a virtue ... but I often have the urge to send a message to Porkjet to ask if we can have those wheels sooner ... bad me, bad me.

We need smaller jet engines too.

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Failed experiment:

http://i.imgur.com/cL31EHv.png

http://i.imgur.com/kzXTyL8.png

All power is being consumed by internal drag, above 11 rad/s. It's got some drag spikes too, sometimes costing 2-3 rad/s for a moment.

Too bad, because it's VERY strong and VERY reliable. Good looks too! Maybe useful as a wheel bearing for a tank? Lots of parts though, and a Bravo India Tango Charlie Hotel to build.

Whats that little part below the cubic strut in the last pic?

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That's an IR adjustable rail, for testing purposes.

Lotsahn, I've tested your Speedrunner engine + prop. It does a whopping 107kN at 76% power! I don't have results for higher settings, the shaft disembarked twice at 85%.

Very powerful indeed! Yet the prop is a bit unwieldy, had to heighten the test cart for it. I'm gonna try my 3 blade variable prop now.

Edit, with my variable prop I get 118kN at 32 degree blade angle. Tested at 100% throttle, no shaft separation this time!

Testing two different engines I can tell the following: between 25 and 35 degrees blade angle the thrust is pretty constant, above 35 it suddenly starts to decrease rapidly. Very useful info!

My PO4R which I used to set the speed and altitude record only does 96kN and with a lot more drag spikes and wobble.

Edit 2: Wrong. I'm busy with my PO4R. I decreased the blower angle from 11 to 9, result is a much smoother running engine, wobble almost gone. Here comes the fun part: adjusting blade angle between 31 and 33 in steps of 0.3 results in a difference in kilo Newtons!

Edited by Azimech

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Mighty fine engine you have, Lotsahn! Took me hours of tuning to get mine to the same power level, 118kN (7 on the scale).

ZGpwtwz.png

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Mighty fine engine you have, Lotsahn! Took me hours of tuning to get mine to the same power level, 118kN (7 on the scale).

http://i.imgur.com/ZGpwtwz.png

Hey man, how did you calibrate this rig? Did you use one of the stock engines?

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Exactly! I've explained everything over here: http://forum.kerbalspaceprogram.com/threads/112845-Propeller-Thrust-Tester-77-Industries


Important conclusion: a lot of the things we thought we knew about propellers in stock KSP, is wrong. My PO2R engine went from 25kN to 50kN just by replacing the prop, while the speed dropped from 20 rad/s to 10 rad/s!

Edit ... until you really start to fly and discover that the top speed of your plane has dropped dramatically but it can climb at extreme angles.

Edited by Azimech

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A remarkable increase in power and speed

Thanks to my test rig I've solved some problems and learned a lot about propellers!

xC8fKUK.png

WdzClMj.png

02uStsP.png

Z1X0Y3y.png

From a top speed of 110m/s at 9500m, to a top speed of 133m/s at 8400!

In a dive (was hard to go vertical btw): 221m/s.

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No good. This shot was taken using hack gravity. In reality the thing came 1 meter off the ground but was hardly controllable.

tsJAFBR.png

Not sure I want to develop this further.

It's supposed to be like the Heinkel Lerche.

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Incredible ... I had an 8 blower engine this morning that only produced 85kN. After some work it now produces 183kN! Even more bizarre: I uprated a single row, 4 blower engine with 4 extra blowers ... it now produces 217kN! I can ditch my other, multi row 8 blower designs.

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Mighty fine engine you have, Lotsahn! Took me hours of tuning to get mine to the same power level, 118kN (7 on the scale).

http://i.imgur.com/ZGpwtwz.png

Glad to hear it. I spent a good while tweaking it. :) Low partcount and weight too!

While RU prop departure does happen with big props, it doesn't happen with small ones, and the engine itself should never really explode at any RPM. :) If it starts seizing, though, you'll have to rework the turbine blades by either adjusting the offset to move them toward the center of the shaft, or tilting them. Tilting will increase max RPM at the cost of efficiency--I'm not sure about adjusting the offset. For the speedrunner engine, I kept the propeller big enough that I didn't have to sack efficiency for RPM.

Like I said, I'd be honored if you just wanted to use my engine in some of your designs.

Also, just so you know, it's Lothsahn (as in Lowth-sane) :)

Edited by Lothsahn

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I'll think about putting your designs to work ... In the mean time I could try to build the P38 airframe in such a way a different engine is plug and play, after that you just need to adapt the cowling for the shape. Something I should do more often, some of my designs are a disaster to upgrade.

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Saw a post showing this off on the sub-reddit last night and had to dive into this thread today.

The work here is amazing. Like seriously, I fancy myself a master in KSP design, and some of this stuff I have a hard time even picturing how it works. (Like what is this? http://i.imgur.com/FXJJZZq.gif)

Nonetheless, I had to jump in and see what I could come up with. After taking a quick look at your trainer plane, and reading some of the various comments here, this is what I've put together as my 1st attempt;

3NL9QsD.png

EnMkkz0.png

Gyfy in flight: https://gfycat.com/KindlyImmaculateJaguar

No clue where it would rate on your power scale, It's 14.5 tons and cruising at 25m/s at 2/3 throttle in that clip. It'll do 35/m at full throttle at 200m above sea level, but flight is stabler when kept a 2/3. (No malfunctions at full, SAS just bounces a bit) the goal behind the design, beside being my 1st attempt and learning how to make one work, was to be compact and part efficient. The engine and prop section is under 75 parts, and the entire aircraft is under 150. haven't looked into your tuning utilities yet, so basically it's just tuned very roughly by eye. 4 engines, 4 blades, each blade is 3 segments overlapped maybe 25-30%, blades are rotated at 45 degrees I believe, & I think engine rotation is 25 degrees. Haven't tested max altitude or speed at altitude yet, but I've run it for 45 minutes in a row without touching the controls.

I'd love to hear your thoughts and suggestions.

Edit; just did max altitude speed test, I maxed out at 5250m @ 62m/s, with the end limit being draining the last bit of fuel shift CoM forward enough that I couldn't pitch up enough to climb any higher. The prop held strong, and if anything actually smoothed out a bit at max throttle once I was above 3.5k, after fighting me a bit at full throttle between 2 and 3.5k. No issues with prop in a dive over 100m/s either.

Edited by Yargnit

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