Azimech

[Stock Helicopters & Turboprops] First flight around Kerbin! (page 49)

1703 posts in this topic

No worries. As you can see, you can move the jets quite a distance from the one octagonal strut.

Ruv6iqx.jpg

Share this post


Link to post
Share on other sites

Just mounted this on the Yelling Gazelle. The propellers are very large, and they put out so much torque that it actually pulls the shaft out the front. Looks like I'll have to reinforce the front wheels for larger props.

Hadn't tested on any props this large yet. :)

I got the engines fixed to test the thrust, and I think I'm getting thrust that's comparable or better than the stock Gazelle engines. I'll do some more testing and let you know some better results tomorrow.

Edited by Lothsahn

Share this post


Link to post
Share on other sites

Here are some shots of my new experimental engine. I am definitely using NCS adaptors now, they worked first time without having to angle the wheels.

DSuPQhc.jpg

HskJOVf.jpg

JhdCvX9.jpg

EyLKkL2.jpg

It's an intricate piece of kit though. About 237 parts. Mass = 29.1 tons. You can see by the rotor part separation that it is very fast though.

Edited by Redshift OTF

Share this post


Link to post
Share on other sites

Great stuff people! Tip: install VOID, then, when you switch to the rotor axle, the advanced HUD will show the rotational speed in rad/s. Makes tuning much easier.

Share this post


Link to post
Share on other sites
It's an intricate piece of kit though. About 237 parts. Mass = 29.1 tons. You can see by the rotor part separation that it is very fast though.

That's insane. I thought you broke the prop. That's just rotor separation. Haha.

Share this post


Link to post
Share on other sites

And this is what happens when you try to go too BIG... You get a monster like this.

jak20flicker_zpsaa4fac13.jpg

Weights 65.3 tons, has 500 parts, and is so big it barely fits in the tier3 VAB.

And as you would expect from these figures, it's not really the best flier. Tip of the day: Try to keep your helicopters as small and light as you can. Going huge just makes things too heavy to fly well. Looks good though...

Share this post


Link to post
Share on other sites

Depends Jakalth ... I've made the biggest helicopter in KSP and it flies reasonably well. The problem is those MK3 parts, they're so heavy! I rather build my own cockpit than spend another 3.9t on that Space Shuttle thing.

- - - Updated - - -

New aircraft! My first single engined turboprop! Has a new engine, my strongest and most reliable 4 blower yet! Takeoff weight is 30t. I've reached an altitude of 8050m with a level flight top speed of 75m/s. Flying time at full power: 46 minutes. During a shallow dive from 7500m I reached 110m/s, after which the tanks ran dry.

Javascript is disabled. View full album
Edited by Azimech
1 person likes this

Share this post


Link to post
Share on other sites

Oh wow, I love both of those designs. The helicopter looks like it could be an awesome heavy lifter if modified. The cockpit of the fighter plane looks really good. The ion engine as a glowing dial is a cool idea. :)

I'm not sure if anyone is interesting but you can get significantly more lift on rotors or propellers by adding a control surface to the ends. Some people might consider it a bit cheaty but it does allow for more realistically sized props and rotors so I think it should be allowed.

I am currently working on a Chinook design. It's mostly done but I have discovered the reason for the main problem most helicopter designs have and that is the rotors bending in one direction. This problem slowly magnifies until either the rotors break or get ripped out of the bearings. It looks like the problem occurs when moving forward and it is due to the front sweeping rotor getting more lift than the back sweeping rotor and the front sweeping rotor ends up with more lift and bends upwards and vice versa. Adding canards on the ends of the rotors can solve the problem if placed correctly but I have to analyse exactly how the works so I can replicate this more precisely.

Share this post


Link to post
Share on other sites

Yeah I dislike control surfaces on helicopter rotors / propeller blades. Indeed because of infiniglide. What I did with Yodeling Yak (my prop plane) is put a few extra wing pieces in the blades. The only solution I can come up with at this moment for the problem of the bending blade: keep your horizontal speed low.

Share this post


Link to post
Share on other sites

New airplane ready for download! Check the OP!

Share this post


Link to post
Share on other sites

If using canards on rotors, the standard canard is broken. That monster, 63 ton helicopter can nearly fly without engines, once the rotors with standard canards on them, are turning due to infiniglide. Replace the standard canards with the av-r8 winglet and it no longer infiniglides.(<--- this is wrong) But you still get some of the benefits of the canards, like slightly better stability.

Myself, I've been trying to get away from using canard rotors. They are a bit too powerful at the moment and it's a better challenge to do it without using canards.

Added info, using the big helicopter I have as a base: (auto rotate is with engines turned off while at altitude of 300m)

Conventional rotors, no control surfaces: Climbs at 7 m/s @100% power, takeoff at 85% power Auto rotate descent at 14 m/s

Deluxe Delta rotor tips: Climbs at 9 m/s @ 100% power, takeoff at 65% power Auto rotate descent at 4.2 m/s

AV-R8 Winglet rotor tips: Climbs at 12 m/s @ 100% power, takeoff at 55% power Auto rotate descent at 0 m/s(auto hover... bad...)

Standard Canard rotor tips: Climbs at 15 m/s @ 100% power, takeoff at 30% power Auto rotate descent varies between 3 m/s and -15 m/s(keeps climbing past 1200m very bad...)

Advanced Canard rotor tips: Climbs at 14 m/s @ 100% power, takeoff at 30% power Auto rotate descent varies between 3 m/s and -15 m/s(same as standard canard except climbs slower under power, and is less stable, far less stable...)

And that is why I'm trying to move away from using canard tipped rotors. Only one I'll use now is maybe the Deluxe Delta due to it having the smallest infiniglide effect.

Edited by Jakalth

Share this post


Link to post
Share on other sites
New aircraft! My first single engined turboprop! Has a new engine, my strongest and most reliable 4 blower yet! Takeoff weight is 30t. I've reached an altitude of 8050m with a level flight top speed of 75m/s. Flying time at full power: 46 minutes. During a shallow dive from 7500m I reached 110m/s, after which the tanks ran dry.

Yeah, but you cheated! You're getting all that extra speed from the ion engine in the cockpit!

I LOVE the inside cockpit detail. It's AMAAAZING.

Just checked out your engine. Pretty interesting design--should have a high max RPM--you've got wheels directly on high m/s parts. Very nice.

Edited by Lothsahn

Share this post


Link to post
Share on other sites

Thanks! No more tanks or adapters for sure, just the structural fuselages from now on.

Share this post


Link to post
Share on other sites

Structural fuselage used for the engine huh? Seems we had the same idea. Used that for the engine on the big heli as well. Did you use any struts to keep the fuselages from separating under high stress? I found using one of the long "M-Beam" pieces, run through the center of the fuselage pieces, with some struts connecting it to each fuselage, kept them solidly joined and the bearing spinning strait. Very strait in fact. It barely flexes while doing a painfully slow, full speed roll.

Share this post


Link to post
Share on other sites

No, I used a single fuselage part for both bearing and turbine, with a bunch of those short I beams embedded as turbine blades. After that a single M beam for propeller attachment and some adapters to increase prop diameter (in the end I even used the 3.75m). I've found that using this setup can lead to problems with the colliders if all the landing gear is installed identically front & back (or up & down), which means all the wheels tend to move in and out of their suspension struts at the same time. The collider mesh is a simple one with only 8 sides I believe - and I used 8 wheels. Thus creating a rubbery joint between fuselage and beam that's jerking back and forth, lowering max rpm and losing a lot of energy due to drag. I used struts to remedy this, the mass of the propeller blades pulls the rest through. Widening the gap between the wheels and fuselage didn't make it less, it made it worse. Took me 2 hours to find.

Share this post


Link to post
Share on other sites

I see that you made a new aircraft, but do you think you can take up this challenge? Make a pusher aircraft? Like these, but in all seriousness, it would be cool to see this in KSP

HyX9k6T.jpg

7Z8QIUP.jpg

T2Jkqm5.jpg

1 person likes this

Share this post


Link to post
Share on other sites

By chance, I was experimenting with a Piaggio Avanti and a DO-335 setup today :-)

Ie8zy8p.png

9AvD9om.png

Both are very crude btw, far from finished products.

So yeah, I love pushers. Especially the Beechcraft Starship :-)

Beechcraft_Starship_fly-by.jpg

1 person likes this

Share this post


Link to post
Share on other sites
Thanks! No more tanks or adapters for sure, just the structural fuselages from now on.

Azimech,

I wouldn't give up on tanks and adapters yet! The Juno D211 uses them quite effectively, partially based on your Yelling Gazelle. It provides roughly 20% more thrust than the Yak's engine and weight 1T less. I think the NCS must be more slippery or your angled wheels are adding more drag.

In any case, even with my engine, I was unable to break your speed or altitude record--it's pretty much limited by the ability of the control surfaces to counter the propeller thrust--the same thing I was seeing with Stuka. I actually had to throttle down the engine to 75%, or the plane became uncontrollable around 7500m.

I also tried the modified Yak in a dive, resulting in a massive explosion at 160m/s. Things came apart so fast I couldn't figure out what the root cause was.

Craft file here:

Yodeling Yak with Juno D211

Feel free to use my engine in any of your designs. It's small, light, and high RPM. Its only drawback is it cannot handle extremely heavy props.

Fun Note: The altered COM on the Yak when using the Juno means you have to structurally reinforce the Yak's tail or the tail will slam into the ground and explode when loading the craft.

The Yak is beautiful as heck. I'd love to see a P38, if you have time. I think the counter-rotating props would allow for even higher altitude and faster speed records, as the forces would balance themselves out.

http://en.wikipedia.org/wiki/Lockheed_P-38_Lightning

Edited by Lothsahn

Share this post


Link to post
Share on other sites

I love it, all this tinkering! I'm glad people really try and do different things with all these planes.

Yes, I'm gonna try the D211 in the Yak :-)

The P38 ... that thing screams it's gonna need a lot of parts. I think we should start using mods to keep the weight down and make it look good. I'll look into it.

Share this post


Link to post
Share on other sites

I lengthened the engine of the Yak and installed 4 additional blowers + turbine blades. The increase in speed at sea level is dramatic! From roughly 30 to 57m/s!

ctXfmVo.png

X1dHwl5.png

Engine top speed at sea level went from 14 (133 rpm) to 20 rad/s (190 rpm)!

Current red line is 28 rad/s (270 rpm), I'm starting to get vibrations and something starts to hit something.

And indeed, an explosion at 29 rad/s. The rear part of the turbine axle exploded, curiously enough without collateral damage. The front part stayed in place, including the prop. The cause is turbine blades expanding too much and hitting the support beams.

Edited by Azimech

Share this post


Link to post
Share on other sites
I lengthened the engine of the Yak and installed 4 additional blowers + turbine blades. The increase in speed at sea level is dramatic! From roughly 30 to 57m/s!

Engine top speed at sea level went from 14 (133 rpm) to 20 rad/s (190 rpm)!

Current red line is 28 rad/s (270 rpm), I'm starting to get vibrations and something starts to hit something.

And indeed, an explosion at 29 rad/s. The rear part of the turbine axle exploded, curiously enough without collateral damage. The front part stayed in place, including the prop. The cause is turbine blades expanding too much and hitting the support beams.

Azimech:

How do you see what the rad/s of the blades are?

To solve the engine explosion, use tougher blades. Take a look at the Juno D211D--I use the 1x1 panels, which support collisions up to 80 m/s. I also make sure that if they collide, they'll hit the i-beams (not the jets!), which also have a 80 m/s impact tolerance. This ensures that I get jams (or in severe cases, the shaft dislodges), but no explosions. It does require a *slightly* larger engine space to have the jets above the i-beams, but I consider it a good tradeoff.

The problem with the plates is they are big, so they'll start impacting sooner than the smaller blades you use right now. To solve that, I tilt them in the Juno engine, which increases the gap between the i-beams (and therefore, the max speed) before they start colliding. Interestingly enough, testing shows little or no loss of RPM by tilting the panels, which I would not expect. As a result, the Juno doesn't explode during overspeed conditions--only jams--and usually is recoverable from jams with a throttle down. You can probably use this strategy to make your engine indestructible.

The only time I've gotten an engine explosion is from diving with the Yak at 160 m/s. I'm not sure the cause, but I think the shaft might be ramming into the rear of the engine--Juno was designed for a puller prop. I think there's a parts collision at the rear of the engine, as it's stressed for pulling forces, not pushing ones. I tested adding rear wheels to make it work as a pusher, but adding more wheels lowered the efficiency slightly, so I never kept those modifications.

Redshift also recommended strutting the turbine blades to the shaft, as this might help separation. I haven't really worked with it much, as tilting the blades resolved all of the issues for me, but it's something you might try.

Also, if you're getting vibrations, you might try strutting the wheels holding the structural fuselage together. Reducing their vibration goes a long way to making a much more smooth running engine.

Edited by Lothsahn

Share this post


Link to post
Share on other sites

Don't worry. I use the M650 I-Beam, those have an impact tolerance of 80 as well. Strutting the blades doesn't help at all I'm afraid. What could be the case is the blowers burning the shaft to pieces, the structural fuselage is less heat resistant than the I beams, but they also fail after a long period. Strutting the bearing wheels is what I've been doing since day 1 :-)

What I'm going to do is increase the gap between the support beams, in theory there would be enough room under the bonnet of the Yak but I'd rather build a new plane with the lessons learned. I will release this uprated Yak 8-blower, but will increase the prop pitch with another 10 degrees.

To read the rpm, install V.O.I.D.

https://kerbalstuff.com/mod/253/VOID

It only works on the root part. Since a turbine shaft becomes decoupled, this is no issue. Switch focus to see the value in the advanced HUD.

- - - Updated - - -

What do you think of this?

4iuKY1k.png?2

1 person likes this

Share this post


Link to post
Share on other sites

My new engine is a bit longer so I can use 2x2 plates that are moved through the shaft so they look like 2 1x1 plates stuck together. This stops the plates from hitting the supports due to centrifugal force. The only problem is I have to use an odd number of them which may cause some instability at high speeds but it works well enough with struts on the corners.

You can download it if you want to examine it. It opens in the VAB. I haven't got around to mounting it on anything yet.

Share this post


Link to post
Share on other sites

I'll test it soon, Redshift :-)

Right now I'm stoked to test this one. Does this look vaguely familiar?

qThQxnV.png

nywohus.png

Share this post


Link to post
Share on other sites

Flies at first try! Engine works fine! Me=happy!

06KpNsS.png

eJs2pYC.png

By the way, I solved the propeller problem. From now on we can fly planes with the proper amount of blades :D

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now