Junkers Juno Tournaments (Season 1)

[He_162]

On 7/30/2016 at 2:10 AM, swjr-swis said:

That part is clear, and I am not arguing this; it's your challenge, you set the rules.

In the specific case of the twin bomber category, there is no one to beat, so that's not the issue. No one has yet entered a design that meets the requirements. What I'm trying to say is that this is not by chance: the combination of requirements do not appear feasible, because of the disproportionate weight of fuel and ore requested compared to the other three categories.

The first two categories can be designed to a 1.1+ TWR and hardly any drag. Not enormously challenging, literally my first attempt already exceeded the requirements. The last category has a lot of drag due to the bombs and fuel, and starts at a low of 0.5 TWR with 4 junos, but by going up to 8 junos it can reach a 1.1+ TWR too. Challenging, but still feasible because there is room to play with optional extra engines. But the twin bomber is stuck with 2 junos at around a 0.4 TWR, with very little room to improve it, and it is far from meeting the requirements. At least in stock.

Anyway, no harm done, I'll just skip the twin bomber category. Should be interesting to see what entries make it to that board.

 

A question: what is considered 'turn time' for the purpose of this challenge? I've been wondering since Cunjo asked. I assumed it meant fully reversing the direction of travel (eg. going from a 90 to 270 degree heading), but I'm wondering if you actually mean it to be a full circle 360 degree turn that exits to the same heading as it was entered.

I'll load up the craft and redo the turns to time a 360 full circle, just in case, as that obviously takes longer than just reversing the direction of travel.

360 loop in horizontal flight.

 

Yes, it is challenging, I will upload a craft that can easily do it myself soon.

 

I'll let you know that the SR-71 has a lower thrust to weight ratio. T/W is entirely irrelevant, so long the thrust to drag ratio is not above 1, and the lift to weight ratio is above 1, and the wings are placed in such a way that it works.

[DoctorDavinci]

@He_162 - My craft gets to altitude in 2/3rds the time as yours, has a higher top speed than yours, is amazingly maneuverable and can quite accurately drop it's payload at over 200m/s ... So your saying that your craft is better than mine?

Edited August 1, 2016 by DoctorDavinci

[qzgy]

I do think the scoring should be better, as in more precise...

A formula, such as (Fuel Units)+(Top Speed (m/s))/(Turn time in seconds)+(time to 7km in seconds)), but better balanced

And for the multiengine bomber, penalize the number of engines too

Edited August 1, 2016 by qzgy

[He_162]

5 hours ago, DoctorDavinci said:

@He_162 - My craft gets to altitude in 2/3rds the time as yours, has a higher top speed than yours, is amazingly maneuverable and can quite accurately drop it's payload at over 200m/s ... So your saying that your craft is better than mine?

I apologize, I was tired, and I was reading the stats wrong, I read someone elses craft stats instead of yours, I will change it.

3 hours ago, qzgy said:

I do think the scoring should be better, as in more precise...

A formula, such as (Fuel Units)+(Top Speed (m/s))/(Turn time in seconds)+(time to 7km in seconds)), but better balanced

And for the multiengine bomber, penalize the number of engines too

I will do this system in the next Challenge, which means at the end of this month if I don't get too many more entries.

[Cunjo Carl]

I made a thing! I hope it's close enough to fit. It's a 2 Juno bomber, believe it or not.

Those little Junos are exquisitely sensitive to parasitic drag, so the only place to put the bombs is in 1.25m service bays. Everything else (even the mk2 bays) are much too draggy. Unfortunately, even though 2 radial ore tanks can handily squeeze into a 1.25 service bay, they don't quite fit out the door! It would need a Kerbal to get out and jump on them, which come to think of it does sound like a rather Kerbal thing to do. It was frustrating because I found that I could make my bombers hit the performance benchmarks even with 4x 1.25 service bays, enough space for 8 bombs! But it just barely didn't work.

So instead, I spent a bunch of time and learned how to load the service bays with seperatrons. Lots and lots of seperatrons- like 50 each! These could hypothetically be ignited and launched out, but I preferred to separate them before takeoff and drop them like millions of little feathery snowflakes. They delicately fall and for some reason explode like an inferno when they touch the ground. Well, it's KSP! The end effect has been outstandingly fun to play with, the only trouble is I feel kinda bad bombing anything, so I've gone for using them for plowshare activities like seeding reefs and tearing up concrete. Having spent many hot hours bouncing sledges off of too-well-rebarred concrete (it payed the bills), I feel it's an appropriate escalation and response.

Specs
256m/s  Top speed, level flight profile with bombs but no fuel. Fully fueled is 237m/s
4            Bomb bays, each with 40-60 sepratrons
1360      Fuel. Holla!
5s          360 degree horizontal bank, loosing 2/3 of the velocity.
3:30       Climb from sea level to 8km, with bombs but no fuel.

Above all, it feels nice to fly. Understandably, it drops a bunch of speed during hard maneuvers, but it's stable responsive and quick to turn. Being mostly wing, it has a huge lift/mass so it can keep flight at quite low speeds, making it's easy to recover from stalls. The biggest downside is that it's pitiably slow to accelerate, so you need to keep a careful eye on your energy.

Rebar Ripper

Need fast? You got it! Just wait 5 minutes for it to speed up first                                                  So many crammed in such a small space... It's just like flying Delta. Oh, snap!
Seperatrons scatter out for coral reef seeding. Sorry about those earlier bombs, atolls!                     The Rebar Ripper rips rebar. Potholes beware, you will be replaced. Your days are numbered.

Since we can't use imgur, I've taken to using the KSP forum table for images- It's a little messier, but seems to work well enough. It's been fun putting kerbal smileys in the captions, but I may have gone a little overboard this time.

Oh, If anyone's interested, I'd be happy to describe how to do the seperatron bomb bay thing! Yes it scales up.

Edited August 4, 2016 by Cunjo Carl

[qzgy]

8 hours ago, Cunjo Carl said:

Oh, If anyone's interested, I'd be happy to describe how to do the seperatron bomb bay thing! Yes it scales up.

I am actually quite curious. How?

[swjr-swis]

9 hours ago, Cunjo Carl said:

I made a thing! I hope it's close enough to fit. It's a 2 Juno bomber, believe it or not.

Those little Junos are exquisitely sensitive to parasitic drag, so the only place to put the bombs is in 1.25m service bays. Everything else (even the mk2 bays) are much too draggy.

I'm glad someone else has been trying their hand on the twin bomber, and confirming what I already stated.

We ended up with very similar designs too, at least part and concept wise (although I like the 'backwards' placement of the main wings on yours). I'm not sure there is much better that can be done, other than assembling huge multi-part wings made entirely of the basic fin, which has by a tiny margin a better lift/weight ratio than any of the other lifting surfaces.

 

9 hours ago, Cunjo Carl said:

Unfortunately, even though 2 radial ore tanks can handily squeeze into a 1.25 service bay, they don't quite fit out the door! It would need a Kerbal to get out and jump on them, which come to think of it does sound like a rather Kerbal thing to do. It was frustrating because I found that I could make my bombers hit the performance benchmarks even with 4x 1.25 service bays, enough space for 8 bombs! But it just barely didn't work.

The fit is one issue. A second issue is that the center of mass of the ore tanks -according to the game- is not where you would expect: it is located at the edge where the radial tanks attach, and not in the tank itself. This causes weird displacements of the entire plane's CoM and unexpected rotations when trying to release them in the tightly fitting space of the service bay.

I did solve it the (a?) Kerbal way: not quite stamping on them, but by placing sepratrons (moar boosters!) on the top to make the release rocket-powered. Took some trial and error, but it's 100% reliable this way.

Even then though, it proved impossible to meet the top speed and climb rate requirements. I only barely made the speed benchmark and while it was at level flight, it was only after pulling up from a loooong dive to build up enough excess speed that I could level out and still be over 250m/s. And the climb was only possible within the 10min mark by dropping all bombs. I finally gave in and made a version with drop tanks so I could drop most of the fuel immediately after take off but that was not enough by itself.

Turns can be done very fast, well within 20 secs if you leave the pitch authority at 100%, but to make the craft stable and nice to fly at different speeds I find it requires managing those sliders carefully.

Anyway, I don't consider mine a successful attempt, but you're free to take the service/bomb bay and see if it gives your version the edge it needs to make the mark. Craft files available here. The Mk2 was before I figured out the CoM issue and two of the four bays still need to be rotated 180 degrees to compensate for that. The Mk3 I think performs the best, and the Mk4 was an attempt with drop tanks, to get the climb and top speeds by dropping fuel and bombs right after take off.

Craft files in this folder

Screenshots in this folder

 

Edited August 4, 2016 by swjr-swis
correct links

[He_162]

I barely made a successful attempt, and I think it would be too hard to do without clipping, and using kerbal engineer, so I will lower the challenge requirements for the twin engine bomber to 600 units of fuel, and a top speed of 220 m/s.

[Cunjo Carl]

16 hours ago, qzgy said:

I am actually quite curious. How?

We can take advantage of the very low maxtemp and skin mass of the basic fin. A single seperatron with only .8 fuel can explode it handily, freeing whatever is attached to fall gently down. If you load your basic fin with a bunch of empty seperators and put it in a service bay, you can seperate everything apart before launch and drop them whenever you please. The act of separation is very laggy, but the game handles it well afterwords.

You can see the basic fin on the left. I just placed seperatrons in it, then shifted them slightly out.              Launch! Only one seperatron on each fin has fuel. Normally I launch with the doors closed.
Yay, ball pit! Bill and Val jump into 1000+ seperatrons, well more than a Kerbal deep.                                 The alternative is @swjr-swis's ore tanks loaded in on .625 decouplers and pushed with sep.tns.

 

16 hours ago, swjr-swis said:

We ended up with very similar designs too.

Your plane looks strikingly familiar! It's just about identical to mine only two versions back. It flew nice, so if I didn't need to go crazy to get the speed benchmark we'd probably still have a matching set!

16 hours ago, swjr-swis said:

I did solve it the (a?) Kerbal way: not quite stamping on them, but by placing sepratrons (moar boosters!) on the top to make the release rocket-powered. Took some trial and error, but it's 100% reliable this way

I actually tried that, too unsucesfully. Your use of the .625 seperator and 4 seperatrons really works a treat! Thanks for the pics and craft file. Sporting @swjr-swis (tm) bomb racks has made this plane fit the challenge and hit its marks! Satisfied customer, 5 stars, would buy again.

16 hours ago, swjr-swis said:

Even then though, it proved impossible to meet the top speed and climb rate requirements. I only barely made the speed benchmark and while it was at level flight, it was only after pulling up from a loooong dive to build up enough excess speed that I could level out and still be over 250m/s.

The path from 235m/s top speed to 255m/s was a long and arduous one. I got rid of all the fuel tanks except for the NCS adaptor (too draggy), got rid of the struts, flipped the wings (to move the COM forward), put one of the Junos on the main stack and shifted the other nacelle just above it, shifted all the wings up to bring the COM inline with the weird thrust, pre-tilted the wings. and shifted the tail back much further. The result was worth it, but boy it took a lot of trial and error for not too much improvement.

My final version! It has the ore-tank bombs, and now a pair of vertical shuttle strakes near the COM to help it yaw. The only changes to the specs are: max speed now 252m/s and fuel now 1560. It accelerates like a boat, but it can pirouette like a ballerina!

 

Edit: Just noticed your rules change, @He_162, and I think it's a good choice. The original specs were possible but took a looooot of work.

Edited August 5, 2016 by Cunjo Carl

[swjr-swis]

On 8/5/2016 at 7:51 AM, Cunjo Carl said:

My final version! It has the ore-tank bombs, and now a pair of vertical shuttle strakes near the COM to help it yaw. The only changes to the specs are: max speed now 252m/s and fuel now 1560. It accelerates like a boat, but it can pirouette like a ballerina!

Awesome work. I can confirm that this line of design is dangerously nimble even to a surprising slow speed. Limiting the authority significantly on the other hand gets a very nicely handling and stable craft.

One of those designs that prove why RL craft dynamically adapt authority to the circumstances.

[Drone_Kerbal]

I just finished the Quad+ challenge with my Junkers Octo (eight engines as the name suggests). 

http://imgur.com/gallery/jIwIR

Top speed of 272 m/s
Fuel Capacity of 1420 units (only packed 1216 for the ride)
6 radial ore tank bombs in a long Mk 2 cargo bay
180 degree turn time of 8 seconds
1 crew member

Edited August 30, 2016 by Drone_Kerbal