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[1.7.3]Pteron Micro Shuttle and Rescue Vehicle (0.7.0.0) Landing me softly [2020 04 19]


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10 hours ago, zer0Kerbal said:

:D In all seriousness, good observation.

It merits some thinking though. Lifting bodies are not very good lifting devices, the wings help a bit but in general they have high wing (in this case body) loading. The challenge you face is to cfg higher lifting capabilities for your body + tiny wings for better gameplay (which would be unreal) or to cgf lower lift capabilities for more realism (which would make the thing harder to land, since it comes way too fast for a safe landing). 

In my tests it starts stalling at around 55m/s, a bit above that perhaps. In my book that is proportional to great lifting capabilities, but does it match what the eyes can see? That snubby little thing probably couldn't provide that much lift, by looking at it, if you compare to other craft you built that are capable of not staling whilst doing 60m/s. That is just a generic impression of mine,  tho. 

And then we return to the drag issue. I still think this shuttle "feels" a little too slick and dragless considering how it looks like, but then again, if you make it more draggy and at the same time you change the lifting properties of the parts, for sure you will have an unflyable craft: one that can only stay aloft in higher speeds, but that losses speed very quickly - making controlled approaches a very, very hard thing to do, 'cuz the window is very tight.

Note that I am not suggesting you change anything, just bringing up some concerns that would certainly be raised if this were a real-life design.  A real craft like yours would have put engineers on their toes; the small wings and stubby body would probably give poor lift properties, resulting a high stall speed and high wing loading, and at the same time it would probably be somewhat draggy, making it lose speed rapidly. It would demand a perfect landing approach; coming in too far or low and you would miss the runway, and too high and you would overshoot it, with probably no chance of a go-around.

Now consider this. a) The MiG 105 had provisions for a powered landing, if I recall correctly. It was meant to glide all the way down but if a miscalculation happened, the engine could give it some powered capabilities and help it reach the runway (perhaps even try a go-around, I am not sure). I have tried that with your Pteron; what I found is that the two engines provided with the mod can give it an extra boost but not sustained flight; at best they slow down the deceleration rate, but it still loses speed markedly; b) the real life Space Shuttle also suffered from the issue of having too high landing speeds (as, I think, all lifting-body craft must suffer from that malady) and it countered that problem by the means of drogue chutes.

Where I am getting at: too-fast flying birds can counter that with drogue landing chutes to land easier; too easily-stalled birds can counter that with engines that boost it somewhat towards a powered landing if necessary. So why not increase the power of the two engines and put a place there in the rear where a stock chute can be placed? If you want all parts to be included with the mod, hijack the stock vanilla radial drogue and change it's size a bit so that it fits the rear somewhere. 

 

Edited by Daniel Prates
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Posted (edited)
4 hours ago, Daniel Prates said:

It merits some thinking though.

Agree. A well written, well thought comment that is very much appreciated. +1 :rep:

Not much I can do (ability) to adjust the models, and overall have chosen to make err toward playability rather than toward realism.

With that said, I am going to attempt to provide improvements based upon these (and other suggestions)

  • 'Slowing Me Down' :
    • mini-Drogue chute - using scaled down version of a round chute (16) with the stats of a scaled down radial drogue. I don't want to see rectangles on this, and so a round bump feels better visually.
    • I will see if I can also add attachment nodes to them and recess them into the body a hair so they don't look too out of place. Might even attempt to re texture them (stretch). If I am able to add attachment nodes will try to make them work with symmetry so can add both at once.
    • thought also occurs to me that could put the drogue chutes on either the dorsal-stern (top back) inside or the ventral-stern (bottom-back) inside wings
    •  
  • 'Pushing Me Forward' :
    • Upgrade to the miniPuff (the miniSuperPuff) - make the miniPuff a multi-Mode MonoPropellent engine:
      • one vacuum mode (as it is now) 4.5kn @ 270 isp
      • one landing mode: 10-15kn @ 120 isp
      • am considering lowering vacuum isp to 260 and raising the 1 atmosphere to 190 (wobbly numbers)
      • am considering adding a attachment node to the miniPuff on the top. I would also add attachment nodes to either the stern of wings or the body. Would also attempt to make them work with symmetry (if on body)

Did you ( @Daniel Prates )have any issues with the landing gear during landing? too much suspension?

I will keep on the lookout for someone willing to make an IVA - would be great with the new version of RPM that @MOARdV is making.

 

Again thank you for the feedback! Kindly keep giving! Might not seem like allot, but feedback is how we try to make mods better. Hard to improve in a vacuum. :o

Edited by zer0Kerbal
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1 hour ago, zer0Kerbal said:

any issues with the landing gear during landing? too much suspension?

To be honest I only made water landings! I was not able to reach the runway in any of my attempts. Sloppy of me, the flight characteristics of the Pteron are not so bad that I couldn't have landed properly if I have wanted to. By accident though, I did discovered that it is has good water landing characteristics!!!

 

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3 hours ago, zer0Kerbal said:

:huh::o:lol::wink::sticktongue:

Waaat heheheh...but it does! Indeed I am not so much a spaceplane guy, but most of my SP designs are water landers. For one there is a lot of landing room, then there is the part saving, and as long as it can be controlled well in low speeds, it won't break up.  Make sure it is buoyant tho.

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10 hours ago, Daniel Prates said:

It merits some thinking though. Lifting bodies are not very good lifting devices, the wings help a bit but in general they have high wing (in this case body) loading. The challenge you face is to cfg higher lifting capabilities for your body + tiny wings for better gameplay (which would be unreal) or to cgf lower lift capabilities for more realism (which would make the thing harder to land, since it comes way too fast for a safe landing). 

In my tests it starts stalling at around 55m/s, a bit above that perhaps. In my book that is proportional to great lifting capabilities, but does it match what the eyes can see? That snubby little thing probably couldn't provide that much lift, by looking at it, if you compare to other craft you built that are capable of not staling whilst doing 60m/s. That is just a generic impression of mine,  tho. 

And then we return to the drag issue. I still think this shuttle "feels" a little too slick and dragless considering how it looks like, but then again, if you make it more draggy and at the same time you change the lifting properties of the parts, for sure you will have an unflyable craft: one that can only stay aloft in higher speeds, but that losses speed very quickly - making controlled approaches a very, very hard thing to do, 'cuz the window is very tight.

Note that I am not suggesting you change anything, just bringing up some concerns that would certainly be raised if this were a real-life design.  A real craft like yours would have put engineers on their toes; the small wings and stubby body would probably give poor lift properties, resulting a high stall speed and high wing loading, and at the same time it would probably be somewhat draggy, making it lose speed rapidly. It would demand a perfect landing approach; coming in too far or low and you would miss the runway, and too high and you would overshoot it, with probably no chance of a go-around.

Now consider this. a) The MiG 105 had provisions for a powered landing, if I recall correctly. It was meant to glide all the way down but if a miscalculation happened, the engine could give it some powered capabilities and help it reach the runway (perhaps even try a go-around, I am not sure). I have tried that with your Pteron; what I found is that the two engines provided with the mod can give it an extra boost but not sustained flight; at best they slow down the deceleration rate, but it still loses speed markedly; b) the real life Space Shuttle also suffered from the issue of having too high landing speeds (as, I think, all lifting-body craft must suffer from that malady) and it countered that problem by the means of drogue chutes.

Where I am getting at: too-fast flying birds can counter that with drogue landing chutes to land easier; too easily-stalled birds can counter that with engines that boost it somewhat towards a powered landing if necessary. So why not increase the power of the two engines and put a place there in the rear where a stock chute can be placed? If you want all parts to be included with the mod, hijack the stock vanilla radial drogue and change it's size a bit so that it fits the rear somewhere. 

 

The problem with the aerodynamics on this craft are two fold.  First the craft is too small, leaving the control surfaces with little authority.  Without excessive lift characteristics the control surfaces cannot pitch it up.  I spent a long time trying to get the thing to pitch while forcing proper high speed lifting body dynamics, but I simply couldn't find a good balance.  I smashed, nose first, into the ground for around 8 hours before I gave up and just settled on what you see.  This also forced a seriously excessive % of control surface, because a realistic number, 10-20% by my visual observation, leaves the craft with absolutely no ability to pitch.

Secondly, the drag is difficult to modify because if you up the drag much more, then you cannot pitch up without bleeding massive amounts of speed.  Much of this is attributed to the control surfaces being integral to the wings.  This means every time you pitch or roll the drag skyrockets.  If the control surfaces were separate you could reduce control surface drag, and have a higher wing surface drag that is more affected by AoA than just trying to maneuver normally.  As it is, if the elevons move they throw maximum drag into the airflow.  This can be mitigated somewhat by using a joystick/controller with better control nuance, but I'm a keyboard pilot myself.

I suspect there are also issues with the centre of lift being so far behind the centre of mass in the wings.  In all my checking, for this project, I did not find a stock part where the CoL and CoM were not the same on the part itself.  If the control surfaces were separate the wings and controls could all be made with CoL and CoM centred, but the elevons need to have control very far back in the wing parts.

I would be more than happy to see someone make adjustments to this craft but, despite my ability to make quite a few SSTO space planes out of KSP parts, I am not able to figure out how to manipulate the actual part files to make this any more realistic while still flyable with KSP physics.

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@overkill13 I totally agree with all that you said, also in the other posts. As a matter of fact, I don't think a craft quite like Pteron here would be feasible in real life. Lifting bodies were experimented enough to be clear that they are ineffective craft in low speeds. In fact, the real-life space shuttle still has a lot of wing to help out and it could be considered a partial LB at best. Pteron here, in real life, would have like 90% of it's lift coming from the body and the rest from the tiny wings, so comparing to real world parameters, it would be a very, very fast lander. It is silly to guess numbers at random but imagine a think like that landing at 250, 300 kph or so. 

Still, this being a game, I am all for Pteron becoming a rational, feasible craft, since KSP allows for some margin of imagination. I think that your comments pertaining CoM should be tested, and on top of that, I would at least give it more powerful engines to come closer to a powered landing. I would also diminish the lifting capabilities so that it feels more "real", forcing you keep it faster in order not to stall. 

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I did try to reduce the body lift, to reduce overall lift and force faster landings, while leaving the wing lift at current levels, expecting it to still have the same amount of control.  This was not the case, the control authority fell off for reasons I cannot explain.  If you watch the aerodynamic vectors (F12), you can see the body lift flip violently, opposite the vectors from the control surface, even though the control surfaces shouldn't have any effect on the body lift at all.  Only AoA should cause changes in the body lift.  I feel that this inexplicable change in lift assists with control, but makes it impossible to reduce lift to a point that seems realistic for the craft.

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On 4/22/2020 at 3:33 PM, Daniel Prates said:

To be honest I only made water landings! I was not able to reach the runway in any of my attempts. Sloppy of me, the flight characteristics of the Pteron are not so bad that I couldn't have landed properly if I have wanted to. By accident though, I did discovered that it is has good water landing characteristics!!!

 

The real question: Does it float? :)

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4 hours ago, AmpCat said:

The real question: Does it float? :)

Haha! Oh yeah, that is 75% of what I meant by good water landing characterisrics. 

Really, spaceplanes are not my thing... as in real life, dumb rockets get the job done cheaper.  But most times I tried out SP designs, they ended up being water landers. You have (waaaay) more landing space, less parts, a more permissible window to work with. It however absolutelly must be: buoyant; slow staller; sturdy on contact with water.

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  • 4 weeks later...

Been on vacation - and moving into a new-to-me machine - apologies for the hiatus and slow reply

I have the next update nearly done. Will include several suggestions from this thread.

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It's a really fun little mod.  Thank you.

I think I have detected a conflict between your mod and Restock/Restock Plus.  Your MiniPuff engine does not load when Restock/Restock Plus is loaded.I think the problem may lie with the stock Puff engine which I believe is modified by Restock/Restock Plus.  If I delete Stock/Restock Plus the MiniPuff shows up on the parts list in the VAB and can be attached.  If I reload Restock/Restock Plus the saved ship shows the standard "missing part" message and will not load.

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  • 2 months later...

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