[Stock Helicopters & Turboprops] Non DLC Will Always Be More Fun!

[Gman_builder]

I think a ornithopter would work similar to this. With a turboshaft engine geared up to the wings to do the flapping.

[erasmusguy]

38 minutes ago, Gman_builder said:

I think a ornithopter would work similar to this. With a turboshaft engine geared up to the wings to do the flapping.

looks doable. need to see a few in flight.

1 hour ago, Gman_builder said:

http://forum.kerbalspaceprogram.com/index.php?/topic/98700-stock-helicopters-turboprops-we-keep-on-developing/&page=41

it's a little ways down on that page

cool car bud, we just need a better the engine for it

[Gman_builder]

4 minutes ago, erasmusguy said:

looks doable. need to see a few in flight.

cool car bud, we just need a better the engine for it

Ya I dunno. It performs to it's design specifications. I am thinking of scaling it down and using my latest developed tiny engine.

I just found that pic on the internet, I have no pics or vids of it in flight.

[Azimech]

4 hours ago, erasmusguy said:

ive been experimenting on slower revving engines with high torque but so far had no luck. May be SAS driven would be better for something like this.

I ... don't think so.

4 hours ago, Gman_builder said:

Thing with KSP aerodynamics though is this.

Wing pushes down, equals downward thrust.

Wing pushes back up, equals upward thrust.

Therefore you go nowhere. It's all but impossible to make a mechanic device that can replicate a dragonfly's flight pattern in real life let alone KSP. Especially when we could only dream of achieving the same speeds that a dragonfly's wings beat at.

Someone already built one years ago. Don't ask me for details. Seems @Majorjim has a good memory so maybe he can find it.

[Majorjim!]

Just now, Azimech said:

Someone already built one years ago. Don't ask me for details. Seems @Majorjim has a good memory so maybe he can find it.

Cheers mate, I do for some things, I wish I could choose what though..

 I don't remember one specifically but a quick search reveled this from 2014:

Good luck getting it to work sans soup-osphere though.. Didn't Scott Manley try to make one with mods once?

[Azimech]

1 minute ago, Majorjim said:

Cheers mate, I do for some things, I wish I could choose what though..

 I don't remember one specifically but a quick search reveled this from 2014:

Good luck getting it to work sans soup-osphere though.. Didn't Scott Manley try to make one with mods once?

Even without Errordynamics I believe there's a way. I'm not going to explore that territory though ... already have too much work with my current projects.

[EpicSpaceTroll139]

3 hours ago, Azimech said:

I ... don't think so.

Someone already built one years ago. Don't ask me for details. Seems @Majorjim has a good memory so maybe he can find it.

@AzimechI don't remember about RPM but somewhere I have a light plane that went 75m/s in stock aero powered by RTGs and reaction wheels. Takeoff was a bit tricky and in flight she shook like an off-balance washing machine, but hey! No fuel required!

[erasmusguy]

3 hours ago, EpicSpaceTroll139 said:

@AzimechI don't remember about RPM but somewhere I have a light plane that went 75m/s in stock aero powered by RTGs and reaction wheels. Takeoff was a bit tricky and in flight she shook like an off-balance washing machine, but hey! No fuel required!

we dont talk of reaction wheel powered machines here! I have already angered the master by mentioning sas  

Do you have the craft file though? Id like a look  

[Gman_builder]

3 minutes ago, erasmusguy said:

we dont talk of reaction wheel powered machines here! I have already angered the master by mentioning sas  

Do you have the craft file though? Id like a look  

I agree. They arnt really "turboshafts."

They are their own class of engine.

[EpicSpaceTroll139]

Here's a picture of the thing: https://imgur.com/a/LB9Iu

I seem to have knocked something out of whack; it doesn't shake like a washing machine as much but it also only goes 60m/s now. I'm thinking with tweaking I could get it to match or exceed the old 75m/s.

Anyways, you can try it out here: https://kerbalx.com/EpicSpaceTroll139/Electric-Speedster-Mk7

 

Edited July 30, 2016 by EpicSpaceTroll139
Added "Electric Speedster" + *m/s* not m/

[Azimech]

Are you guys interested in a new challenge?

[Gman_builder]

1 hour ago, Azimech said:

Are you guys interested in a new challenge?

I'm listening

[Azimech]

Build a turboprop with a MK3 crew module, fly to the island runway, land, turn around and land at KSC intact.

Rules: no airbrakes, instead brake using the propeller.

Scoring would be based on elapsed time.

This is a pretty neat challenge because it really tests plane & flying skills.

So it's gotta do everthing: be able to STOL, sturdy enough to handle the MK3 crew module, fly reasonably fast, have enough control, be able to lose speed. etc.

[Rune]

On 27/7/2016 at 1:50 AM, Gman_builder said:

That's in centrifugal RC jet engines. I'm pretty sure a 50,000 RPM prop is impossible in any standard.

I dunno why but I can't post images on here anymore. It doesn't give me the option too.

http://imgur.com/a/f65Ty

That's a helicopter tachometer. You can see the optimal RPM is around 400.

That must have been form a small helicopter.

I say that because optimal RPM is a function of blade length. Basically because the thing that sizes any rotor is not allowing the tips to go supersonic (honorable exception to the notoriously noisy and inefficient tail rotors).

I think my comment was more directed at showing that high RPM is not a synonym of hight thrust... the size of the rotor also plays a crucial part, and a low disc loading (rotor area/heli weight) makes wonders when trying to build a helicopter with power limitations. So basically, maybe you guys should start looking at improving your rotors now that you are running against engine limits... which you seem to be doing already.

 

Rune. All is well with the world.

 

[Gman_builder]

17 hours ago, Rune said:

That must have been form a small helicopter.

I say that because optimal RPM is a function of blade length. Basically because the thing that sizes any rotor is not allowing the tips to go supersonic (honorable exception to the notoriously noisy and inefficient tail rotors).

I think my comment was more directed at showing that high RPM is not a synonym of hight thrust... the size of the rotor also plays a crucial part, and a low disc loading (rotor area/heli weight) makes wonders when trying to build a helicopter with power limitations. So basically, maybe you guys should start looking at improving your rotors now that you are running against engine limits... which you seem to be doing already.

 

Rune. All is well with the world.

 

I noticed you mentioned tail rotors.

Today I got a ride in both a CH-47 Chinook and a UH-60 Black Hawk. I can say from personal experience, the Chinook was WAAAAAYYYY louder than the Black Hawk. Even though it didn't have a "Noisy and inefficient" tail rotor. However the main rotor of the UH-60 is almost exactly the same diameter as that of the Chinook so I fail to see how a tail rotor makes the vehicle any louder.

You can read a lot more on it in this article from NASA.

http://rotorcraft.arc.nasa.gov/publications/files/Shinoda_AHSF02.pdf

But the tail rotor of a UH-60 and all other helicopters does not break the sound barrier. If it did it would be so loud that it would actually cause physical harm to humans too close because of the constant sonic boom. You can see this demonstrated on the F-84H, supersonic turboprop prototype aircraft.

https://en.wikipedia.org/wiki/Republic_XF-84H

Also good examples are the TU-95, TU-142, and TU-114. Which all respectively have props that rotate past the sound barrier. Fighter jet pilots who have to escort those aircraft complain about being extremely uncomfortable and physically sickly because of the extreme noise being produced by the aircraft.

In conclusion, helicopter tail blades do not exceed the sound barrier. If they did, you'd definitely know it.

Side note: Tail blades are also no less efficient than the main disk. As it actually has to counteract the torque created by the entire rotor head, it is beneficial to engineer a tail rotor that can utilize as much energy as possible that it is receiving from the central driveshaft and engines. Since the tail rotor's diameter is smaller than that of the main rotor, it can spin much faster(which it does) and even be quieter because of that. Many tail rotors are the size of a light aircraft's propeller, and as you know, they can spin at thousands of RPM without breaking the sound barrier.

Edited July 31, 2016 by Gman_builder

[Gman_builder]

http://www.thenakedscientists.com/forum/index.php?topic=9839.20;wap2

Interesting article about rotor blades.

[Rune]

52 minutes ago, Gman_builder said:

Today I got a ride in both a CH-47 Chinook and a UH-60 Black Hawk.

Well, lucky you! Unless, of course, it's job-related, and then maybe I should better say "be safe".

Of course the Chinook would be noisier. It's considerably older! Most of that noise in the cabin is coming form the engine anyway, and I'd bet insulation is also considerably better on the newer Black Hawk.

As to tail rotors, the main aim of the NOTAR project was actually noise reduction. And noise means inefficiency, since it's energy being dumped into the air without doing useful work. They are obviously not supersonic arifoils, but the tips come perilously close to it, wasting a lot of energy to tip vortexes and transonic effects. They usually get away with it because the tail rotor doesn't do that much work in the first place, compared to the main, and because it's placed so far from the cabin.

 

Rune. TL;DR: slower, bigger rotors are more efficient.

[Gman_builder]

4 minutes ago, Rune said:

Well, lucky you! Unless, of course, it's job-related, and then maybe I should better say "be safe".

Of course the Chinook would be noisier. It's considerably older! Most of that noise in the cabin is coming form the engine anyway, and I'd bet insulation is also considerably better on the newer Black Hawk.

As to tail rotors, the main aim of the NOTAR project was actually noise reduction. And noise means inefficiency, since it's energy being dumped into the air without doing useful work. They are obviously not supersonic arifoils, but the tips come perilously close to it, wasting a lot of energy to tip vortexes and transonic effects. They usually get away with it because the tail rotor doesn't do that much work in the first place, compared to the main, and because it's placed so far from the cabin.

 

Rune. TL;DR: slower, bigger rotors are more efficient.

Well, the CH-47 isn't REALLY that much older than the UH-60. Only a 12 year difference. The CH-47 is actually really well insulated, it's rotors are just cutting through so much air that it makes much more noise. There's also, you know, the giant open door in the back.

Also, the engines on the Black Hawk are located directly above the cabin and doors. Whereas the engines on Chinook are located at the rearmost point of the aircraft and have their exhaust nozzles pointing AWAY from the cabin. As you know. The noise comes from the escaping exhaust and when your inside the Chinook you are facing the cold end of the engines. So the engines on the UH-60 are actually louder(relatively) than the engine's on the CH-47. Though the larger helo's engine's produce a little more power.  Plus you are about 10 feet closer to the actual turboshaft when you are inside the Black Hawk vs. the Chinook.

I can tell the difference between turboshaft engine noise and rotor blade noise. It's quite distinct actually. The constant hum vs. the chopping sound lol. I can firmly conclude that the rotor blade noise was far louder than the engine noise. Even when you were standing right behind the aircraft. Ironically the loudest and specifically hottest part of the helicopter as you enter is the APU exhaust. That stuff hits 160 degrees blowing right onto your face along with the wind produced by the blades.

It's intense lol.

Whether the noise was because of the fundamental aerodynamic design of the aircraft, or the placements of the engines. I must say, the Black Hawk definitely wasn't as exciting as the Chinook.(Especially entering and exiting)

[EpicSpaceTroll139]

I managed to adapt @Pds314's Parakeet's engine to give an actual tail rotor to a helicopter!It even uses exactly the same fuel as before (it used to use a juno as a tailjet). It does come with the cost of the risk of a tailrotor strike, more parts, and slightly more weight tho. (Craft file coming soon)

Edited August 1, 2016 by EpicSpaceTroll139

[The Optimist]

[Gman_builder]

@The OptimistLookin better. Why are you using static props for all your engines? It just restricts performance.

[EpicSpaceTroll139]

Here's the craft file for the Heli MkII 18-6. Be aware that the tail rotor likes to blow out. https://kerbalx.com/EpicSpaceTroll139/Heli-MKll-18-6

[klond]

22 hours ago, EpicSpaceTroll139 said:

I managed to adapt @Pds314's Parakeet's engine to give an actual tail rotor to a helicopter!It even uses exactly the same fuel as before (it used to use a juno as a tailjet). It does come with the cost of the risk of a tailrotor strike, more parts, and slightly more weight tho. (Craft file coming soon)

That is a beautiful machine.  When you reduce main rotor power I'm assuming tail rotor power gets reduced too.  Does it work as well as it sounds like it should?

 

Speaking of parakeet, I liked how there was only one support bearing and the prop thrust pulled the shaft and held it in place/centered.  I used a pusher prop to the same effect on this flying coffee table, squeezing the shaft between the fuel tank and 2 structural pieces (forgot the part name, the light 8 sided ones) to make a machine under 1000kg.

[EpicSpaceTroll139]

3 hours ago, klond said:

That is a beautiful machine.  When you reduce main rotor power I'm assuming tail rotor power gets reduced too.  Does it work as well as it sounds like it should?

Not really, because the "main rotor torque" is actually coming directly from the panther blowers. The torque from the "main rotor" therefore increases/decreases at the rate it takes the panthers to spool up, which is reasonably quick. The tail rotor however has to wait for the the Juno to spool up (which itself seems to spool up at roughly the same relative rate as the panther), and also for the tail rotor to spin up. The tail rotor takes a long time to spin up. Thankfully, the large number of reaction wheels on the heli seem to take up the slack pretty well, but to be honest, it flew better when it had a Juno acting directly to counter the torque. That's not to mention that I didn't have to worry about it spontaneously exploding.

Edited August 2, 2016 by EpicSpaceTroll139
fixed something

[The Optimist]

12 hours ago, Gman_builder said:

@The OptimistLookin better. Why are you using static props for all your engines? It just restricts performance.

I like the way they look, despite the obvious shortcomings.