Long Range Rescue aircraft design help required

[Shania_L]

Hey guys, yes its another aircraft related help question, but with a twist \o/

I am looking for help designing an aircraft I can use to collect my brave little kerbals after they land, due to my inability to land interplanetry craft accurately on an atmospheric world, this often leaves them many hundreds of Km from the spaceport, sometimes on the complete opposite side of the planet. The purpose of this aircraft is to rescue these stranded Kerbals from wherever their capsule drops.

I am not after someone to build something for me, I want to do this myself, but I do however require guidance or tips on methods to achive it.

I have a few minimum requirements for a craft to fill this role;

It must be able to reach any point on Kerban and return to the spaceport.

It must be capable of carrying 3 passengers.

It must be relatively easy to fly and to be able to land on rough ground with short landing/takeoff ability.

It should be able to fly fast, I dont want to spend hours just recovering kerbals from each mission.

I have tried a few designs already, and I can achive the last 3 points, but the range issue I seem to be having trouble with. I have been able to get 600 fuel units into an arrangement that doesnt move the CoG during flight, but this doesnt get me anywhere near far enough. adding more fuel tanks just creates balance issues.

As you can see this version has plenty of wing allowing it to fly very slowly and glide without power giving it excellant landing characteristics. But you can also see that it has run out of fuel, burning all 600 units and bearly making it 1/4 of the way around kerban.

This was a slightly different approach where I have attemted a sub-orbital skipper aircraft, which has the range to reach anywhere on kerban, but it cannot return due to once again fuel issues. I also love the styling of this aircraft, proper Bat-plane lines

This was never going to be a working design is has a number of flaws (including the 2 passenger cabins which are inaccessible) it was a testbed for the basic jet engines abilities, would using this engine be a more efficient alternative to the turbo-jet for purely atmospheric flight?

Any advice would be appreciated, as you can see I (think) I have the basics of building aircraft sorted, I just need to move up a level to achieve these abilities for my craft.

Thankyou in advance.

Shania.

Edited June 13, 2013 by Shania_L
clarification on accurate landings requirement.

[Yuming]

I just build a standard plane with a ladder system and 3 external seats. It gets the job done, and its only meant to be used in an emergency.

[Ford_Prefect]

I am not a spaceplane-expert, but if you want to reach any destination, so should totally go for a SSTO. Why? Because if you stay atmospherically, your speed is very limited; in higher atmosphere and/or space you can travel nearly at orbital speeds, though. You don't have to acquire orbit every time; suborbital hops will do. Fuel could become a problem, though; it might get hard to build a SSTO which can fly all the way to the other side of Kerbin, land, and fly back. But it's totally possible.

Or you practice targeted landing; it's actually not that hard

[Nurph]

Based on my first around the globe plane, 2 turbojets, 4 ram intakes, and about 1400 units of fuel should be enough for a round trip anywhere with a few stops in between. What altitude are you usually flying at?

[Shania_L]

@ Ford_Prefect, from a Kerbin orbit perhaps a targeted orbit isnt too hard, certainly I can get within range of my current designs, but coming in from Mun or interplanetry space I have no control whatsoever where my return capsule ends up.

The sub-orbital skipper design is what I was aiming for in the second design, I just never have enough fuel to manage a second sub-orbital hop, most often I will use every last drop performing the first one. My pure SSTO design scrapes into orbit and often has to circularise on RCS, so a craft that can perform the feat twice is beyond me at this point.

@ Nurph, how do you arrange 1400 units to be balenced during all phases of flight?

I tend to fly high, purely so that I can travel faster, as I said in my post I dont want to spend hours flying along at 150m/sec.

[Nurph]

Liek dis

I can transfer fuel around in the outer tanks to maintain balence. It's absurdly stable and can survive 2x time warp at 1500 km/s and 21 km altitude at full throttle.

After a bumpy landing.

It actually has 1520 units of fuel, but I had 191 left over after the flight, so 1400 is more of an estimation. Also the stock fuselages aren't very well balenced, the Mk 1 tank has a higher dry mass than the Mk 3

[Markus Reese]

Rescue plane? What I did was built an SSTO with a bit of glide fuel in the SPH. I then transfer it to the VAB save folder. Be sure to change the vessel save file info on the copy to be a VAB, there is a setting in that. I finish up by building a vertical launch to get to orbit.

Tip for a smooth and quick landing? use the Drag shoots. Deploy them right before touchdown. Can repack once down.

[Shania_L]

@ Markus. Umm, an SSTO with a vertical launcher built under it? then its not an SSTO, what you have there is a rocket that returns on wings, think about what SSTO stands for. Also if I am vertical launching then why bother with it being a plane at all? just make some monstrosity that can launch a kerbal escape capable lander.

Drag chutes are unnessisary, my current designs will glide quite comfortably down to 50-80m/sec with or without fuel, making landings virtualy vertical.

@ Nurph, 1400 fuel units will get you a full kerbal circumnavigation?

So, 21km/1500m/sec takes you just over an hour for the full trip if the time log on that screenie is accurate?

What are the sticky out airbrake things on the first picture? is the plane fully stock or has mods?

Can you just set the ASAS on it and sit back? you said you still need to move fuel about though, its certainly an idea though thanks for the input.

[Ford_Prefect]

@ Ford_Prefect, from a Kerbin orbit perhaps a targeted orbit isnt too hard, certainly I can get within range of my current designs, but coming in from Mun or interplanetry space I have no control whatsoever where my return capsule ends up.

The sub-orbital skipper design is what I was aiming for in the second design, I just never have enough fuel to manage a second sub-orbital hop, most often I will use every last drop performing the first one. My pure SSTO design scrapes into orbit and often has to circularise on RCS, so a craft that can perform the feat twice is beyond me at this point.

Just get into orbit before attempting a landing, then

[Shrike42]

You're going to want to cruise at over 10k, I'd suggest 15k-18k, where your turbojets should work just fine on single or double intakes.

To save weight, if you don't use the seats suggestion, the 1-man landercans should suffice, providing a small, lightweight container.

As for 'set it and forget it' ASAS? I believe you can, since I seem to recall being able to walk away from my early machingbird challenges while they were in the air for up to 45 minutes.

Something else that occurs to me: as you were saying that precise landing is a problem, perhaps you can use radial chutes to be more accurate (lower speed & altitude as you approach, nose up, kill engines, deploy chutes (action group, not stage, so you can deploy them again if needed) to halt forward velocity). With sufficient struts, you should be able to land the plane right-side up and ready to take off again. Something else to consider is the use of either a detachable rover with seats to cover the remaining distance, or having roverwheels on the plane itself to help it move over to the target zone.

[Nurph]

I wasn't at 21 km the whole time (was still looking for the ideal altitude) and I landed once on the way around, so it could probably be done faster still. The airbrakes are from B9 Aerospace (great mod, atleast for the re-done plane parts), but the one I flew around the planet first with was all stock and had radial scoops there instead (they have pretty high drag when open so you can kinda use them as airbrakes). I was tapping my trim up and down the whole time to hold altitude, so you might need Mechjeb to hold it steady if you want to walk away for more than a minute or two.

[Aragosnat]

Well if you don't mind going with mods. I know there is a mod that auto balances the fuel. Don't recall the name.

But, if I remember right. Been a while since I tried it. The fuel lines going back from the last to the next to last and so on. I would have try it. But, I cannot sleep.

[Shania_L]

I am not interested in using any mods, including the autopilot mechjeb type things, pure stock options only.

@Argosnat, I had thought that looped fuel systems led to random and unpredictable fuel drain behaviour? as such I have always avoided loops.

[Markus Reese]

@ Markus. Umm, an SSTO with a vertical launcher built under it? then its not an SSTO, what you have there is a rocket that returns on wings, think about what SSTO stands for. Also if I am vertical launching then why bother with it being a plane at all? just make some monstrosity that can launch a kerbal escape capable lander.

Drag chutes are unnessisary, my current designs will glide quite comfortably down to 50-80m/sec with or without fuel, making landings virtualy vertical.

What I meant is that I built it in two stages. Takeoff on runway, land, takeoff, and land was getting quite large and complex. As such, I took the K.I.S.S. Method. Made a single stage ship that can takeoff and land anywhere on kerbal. That is my SSTO so no matter where I touch down, there is no debris or launch problems. The ship is smaller, lighter and more efficient. In rough terrain, the biggest problem for me was it was easier for the ship to break apart on landing. Tougher to control, etc. That is an SSTO stage

At KSC, I wasn't concerned about boosters cause I can make recoverable boosters. Vertical makes for a fast to space with a relatively small ship. I get it up to space, go to wherever I need, then return as an SSTO. Remember, on rescue, there are two takeoffs. One to leave KSC, then the SSTO return. The return is the toughest part.

I can understand the desire to do it all at once. Way back in 0.17, when I was most active, I made a plane that could circle the planet. I could land and lift off anywhere. Key is to keep it light and minimize drag. It was just hours of flight hence why I started just doing the vertical launch and SSTO returns.

[Tank Buddy]

Well, you should use the TruboJet engines as they are more efficient at high altitudes, and the higher you get, the higher your terminal velocity so you can really get it goin' +1000 m/s. Also, try droppable tanks so you can dispose of them when they are empty. This may require some re-arranging, but tis doable. Lastly, are you picking them up just for the heck of it or in .20 do you have to rescue the crew. I've been having no luck updating so I don't know, but you can just End Flight and it will delete the craft attached to the command module and crew.

[Tank Buddy]

I don't think an SSTO is the best way to travel. You have to go all the way up, then down again, and repeat. It would just be better to use high-efficiency jet engines at 30Km, where you can get rockin'.

[sauliukas]

I have Search and Rescue VTOL SSTO which might suit you. It can go to orbit and land twice, has dockable rover, but it is only 2 seater. I think you can use rover seats if you need to rescue more than 1 kerbal. Just haven't tested in flight with Kerbals sitting there. It weights 30t, but it is agile and easy to pilot plane. Just had no time to post it in the spacecraft exchange, will post it then back from work.

Craft as promised

Raven

4 Toggle Vertical Jet Engines

5 Toggle Jet Engine

6 Toggle Turbo Jet Engines

7 Toggle Rocket Engines

0 Lock Steering on rovers back wheels

Edited June 11, 2013 by sauliukas

[Aragosnat]

@Shania_L:

I never had random fuel drain problems. The only ones I remember having was not having the fuel lines in the right order or enough of them or attached to a part that does not transfer fuel. But, it could be I have been lucky or it could be lag related.

[TheFod]

This any good for ya?

[Shania_L]

@ Markus, Ok, I think I know what you were getting at there, an interesting workaround to the 1-shot nature of most SSTO designs. Chuck your spaceplane to the other side of the planet with a rocket, 'Then' it is an SSTO on the way home. A nice idea, it would certainly provide the rapid deployment I require and should be easy enough to make a 4 seater. I will consider this as an option, thanks.

@ Tank Buddy, I can see your point about the SSTO downsides, dragging about the extra weight of oxidiser and in-efficient rocket motors, especially if you need to break atmos twice in a mission.

Drop tanks would be quite difficult to engineer into a balenced craft I think, they would lead to quite a sizable shift in CoG between being fully fueled and dropped.

Can you explain to me how you are flying an airbreathing aircraft at 30km? I havent been able to fly above 21-22km and even then only when I am about to light off the rockets for my spaceplane.

You do not have to rescue them, this is something I am doing for my own entertainment, End flight is still an option, I just want to return my crew to the space centre.

@ Sauliukas, That is a nice looking plane, and you have some pretty big claims for its abilities. I can see the equivilent of ~600 jet fuel and 720 rocket, what is your flight profile like to get 2 flights that break atmos out of that? Also you have 8 of the small radial rockets, 160KN, is that it? but from what I can tell a lot of rocket fuel for them, how long are you burning the rockets for?

@ TheFod, That is certainly a Kerbal looking aircraft! have you any details available for it? Most of your screenshots are nose on so I cannot see a lot of detail regarding fuel distribution and wing loading, could you provide some detail into the design behind this craft as landing on Minmus certainly equates to being able to circumnavigate Kerban Is it able to escape Kerban twice though as that would be a requirement of my aircraft?

Thankyou guys for all the replies, I will get to applying as many of the ideas as I can to my designs and hopefully get some planes that meet my needs.

[mellojoe]

Random question:

If you are OK using an oribatal plane (like the SSTO's mentioned), why not simply oribt your lander before you land? If you can successfully take a plane from runway, to orbit, to Kerbal rescue point and return, wouldn't that be the same as going from deep space, into orbit, and then land?

Or are your return landers just a space pod with no fuel?

I guess the question is more: Are you having trouble landing your Kerbals after a mission due to aim? or fuel?

[rpayne88]

Here's an idea. Take a fuel tank of any size, place a few parachutes and a docking port or RAS refueling port (if you use it,) and build a rocket underneath it. Yes, a rocket. Next, launch it on a sub-orbital trajectory to some point roughly half way between KSC and your Kerbal. Next, build a plane that can reach that point on a one way trip. Repeat this process until you have enough "gas stations" to get your plane to your Kerbal and back to one of them. Then simply fly from KSC to the first station, refuel, and repeat.

[Shania_L]

@ mellojoe, The rescue plane concept is a solution to my inability to aim landers on an atmospheric world. even when I have a powered re-entry vehicle and I am returning from Low Kerbal orbit I will often miss the space centre by upwards of 70kms. However most often I return from outside the Kerbin gravity well and go directly into a deep aerobrake such as I do not achieve orbit, thus I land wherever I happen to be at first encounter. Because I know I have so little control of landing location, I do not bother building powered re0entry vehicles, accept the inaccuracy in exchange for lighter vehicles in total. In regards to your final question, it is both, I do not carry fuel because my aim is bad so I do not bother.

@ rpayne88, RAS fuelling port? is that a mod? if so then no I do not use it. Your concept is very simplistic, practically an antarctic expedition methodology It is however turning what should be a single mission into multiple missions involving many landings and ground based docking procedures (which I have never done) so although it will work, its is somewhat more work than I was intending to do.

On a side note, would this be a bad time to mention oceanic rescue? A VTOL plane capable of round Kerban range and landing on the sea to rescue downed crewmen? ... maybe that is one for the end flight button ehh?

[Markus Reese]

Actually, I have made sea lander VTOLs before. Quite neat and challenging, but they work pretty good. More often for me they look more like an oil platform than an air vehicle.

[TheFod]

@ TheFod, That is certainly a Kerbal looking aircraft! have you any details available for it? Most of your screenshots are nose on so I cannot see a lot of detail regarding fuel distribution and wing loading, could you provide some detail into the design behind this craft as landing on Minmus certainly equates to being able to circumnavigate Kerban Is it able to escape Kerban twice though as that would be a requirement of my aircraft?

Yeah, sure, it has 8 standard jet fuel tanks, 4 turbojets, 4 FL-T800 rocket tanks and 2 NERVAs.

In this pic, you can see the jet tanks and the engine cluster, the FL-T800s are what the NERVAs are attached to, inside the main body.

Hope this helps.