"Fastest" Juno-powered Airplane

[Aetharan]

@Laie and @swjr-swis, I have a proposal for a scoring-system.  Am sure it's stupid, but need you to tell me why.

Score = A + B + C + D - E

A = Top level-flight speed in m/s; B = Range in KM / 6; C = Cargo Capacity in Tons / # of Junos; D = Passenger Count / # of Junos; E = Dry Mass (in tons) * # of Junos

The divisor on range makes a circumnavigation worth roughly the same as the ability to hit Mach 2, setting expectations for A and D at 600ish for soft-caps.  The Dry Mass, Passenger, and Cargo Capacity would need calibration to make them sufficiently significant to matter.  It could be as simple as A + B + ((C+D-E)*100).

(Example calculations for my own AAC-630 would be 630 m/s + 628 for demonstrated single circumnavigation + ((0/4 cargo + 2/4 passengers - 4.495 dry tons * 4 Junos)*100).  Simplifies to 630 + 628 - 1,748 = -490, so I might be over-penalizing for engine-count.)

Edited January 20, 2020 by Aetharan

[HyperDraco]

hmmm, the challenge is compelling me to use 10 junos

[HyperDraco]

I just built the 24 Juno powered Draconic Vex

Test flight speed hit around 740 m/s

Edited January 20, 2020 by HyperDraco

[Zeiss Ikon]

@HyperDraco Better go back and look at the scoring.  As it stands, you're dividing by number of engines.  Unless your twenty-four Junos can get you close to orbital speed or your design masses something above 60 T at speed, you'll probably score lower than my four-engine Fleetfoot III econ.  Better yet, you might want to hold off design finalization until the scoring questions are resolved.

@Laie I'm fine with tweaking the scoring formula, but I'm not sure what's the best way to do it.  As noted above, as it stands, it's basically "how fast can you go at a given TWR", which winds up being more about adding mass than about going fast.  One way i can see where you maintain at least some level of "looks and flies like an airplane" is to require a demonstration of the ability to fly with a pitch below 30 degrees above horizontal, at a speed below, say, 100 m/s.  That'll require at least one more photo from "questionable" entries (nav ball and vertical rate indicator will provide the needed information).  This rule would rule out the "engine and Okto" missiles and some of the ones from the original challenge that looked like a crossbow bolt, but wouldn't disqualify any of the existing entries (that I recall).  Then continue to divide speed by number of engines, but toss out the mass multiplier.

Doing that, Fleetfoot III econ would score around 125, and Fleetfoot III (the 5 engine version) would be close to 120 -- and the temptation to add a bunch of ballast to the latter and refly would be removed.  In fact, there'd be a slight incentive to build light, as a lighter aircraft can generally go faster on the same power, other factors equal.

[Box of Stardust]

Well this was a bit of a surprise notification. The JunoSlab lives!

Fun to see someone creatively repurpose it.

Edited January 20, 2020 by Box of Stardust

[Lisias]

Well, this is my first entry for this contest: The Flying Torpedo Mark 1.

The scoring for the supersonic entry is:

Quote

5.923 Tons / 3 Engines * 600 m/s
score = 1184.6

Some screenshots and evidences by clicking on the image below:

And yes, I shoved 6 pour Tourists on the back seat and scared them to death!  

This is an airplane contest, right? And airplanes usually have passengers (mine have dirty pants by now).

Notes:

3 hours ago, Zeiss Ikon said:

As noted above, as it stands, it's basically "how fast can you go at a given TWR", which winds up being more about adding mass than about going fast.  One way i can see where you maintain at least some level of "looks and flies like an airplane" is to require a demonstration of the ability to fly with a pitch below 30 degrees above horizontal, at a speed below, say, 100 m/s.  That'll require at least one more photo from "questionable" entries (nav ball and vertical rate indicator will provide the needed information).  This rule would rule out the "engine and Okto" missiles and some of the ones from the original challenge that looked like a crossbow bolt, but wouldn't disqualify any of the existing entries (that I recall).  Then continue to divide speed by number of engines, but toss out the mass multiplier.

I'm kinda fine with the current scoring system - but I would like something that promotes speed, not TWR, this is about the fastest, right?

The TWR thingy is true - carefully choosing parts to counter balance the losses by the engine number will improve the score. I considered using Ore Tanks to trim out the score, but choose to use Crew Cabins (and Tourists) instead just because I'm already familiar with the tradeoff of them due other challenge I'm doing. Perhaps on the next entry, when I'have more time to play with parts - if the scoring doesn't changes.

As an additional rule, I would ask evidences for a successful landings - the mention of parachutes on the rules appears to suggest it, but as it stands, the rules allow to add some engines and the landing wheels on stages, eject them off when appropriated, and then score the points - ejecting the landing wheels will help on the drag, and using some additional Junos on the beginning of the speed up will get you to higher speeds faster, saving fuel for the score. And since the score says what matters is the configuration at the moment of the scoring, ejecting engines before it would save you some points.

And publishing the aircraft should be standard, so anyone can check the results at any time.

Edited January 21, 2020 by Lisias
additional rule proposition

[HyperDraco]

9 hours ago, Zeiss Ikon said:

@HyperDraco Better go back and look at the scoring.  As it stands, you're dividing by number of engines.  Unless your twenty-four Junos can get you close to orbital speed or your design masses something above 60 T at speed, you'll probably score lower than my four-engine Fleetfoot III econ.  Better yet, you might want to hold off design finalization until the scoring questions are resolved.

Ah, so the speed is divided by the number of Juno's?

Time for 3 Junos and a 4 ton craft

[swjr-swis]

3 hours ago, HyperDraco said:

Time for 3 Junos and a 4 ton craft

Note that the way scoring is right now, you'll need a ratio of 2.5 to 3 tonnes per Juno to be competitive. This may change though, so don't let that keep you from entering any design you have! You got good speed with that first one.

[Laie]

21 hours ago, Aetharan said:

Score = A + B + C + D - E

A = Top level-flight speed in m/s; B = Range in KM / 6; C = Cargo Capacity in Tons / # of Junos; D = Passenger Count / # of Junos; E = Dry Mass (in tons) * # of Junos

As a generic experience from previous challenges, I'm wary of using too many ingredients. It confuses participants, possibly to the degree of acting as deterrent, and increases the likelihood of asking for the wrong optimization by mistake.

I guess what you're ultimately asking for is a kind of "Juno-Concorde Challenge": able to go (about) Mach2, intercontinental range, and passengers. We could simply write this down as demands, and lowest TWR wins.

However, I currently believe that the simple TWR scoring will still honor speed over mass, at least to a degree. Even in the subsonic department, the Slab loses to my flying wing (which isn't even optimized in any way). I'm not 100% certain how things work in the transsonic area, but think that one still has to make at least Mach 1.5 or thereabouts before adding mass becomes again a winning strategy.

[HyperDraco]

50 minutes ago, swjr-swis said:

Note that the way scoring is right now, you'll need a ratio of 2.5 to 3 tonnes per Juno to be competitive. This may change though, so don't let that keep you from entering any design you have! You got good speed with that first one.

Thank you for the help and encouragement.

Edited January 21, 2020 by HyperDraco

[swjr-swis]

On 1/18/2020 at 4:11 PM, Laie said:

Another five tons of payload, taking off with any more than that would require a longer runway. Again, it looks as i it will do better at altitude, but has barely enough power to climb.

In the transsonic or supersonic regimes, perhaps. Bigger cross-sections do suffer more from the thicker atmosphere at sea level. I noticed this with the Mk3 Dodo, which much preferred a bit of altitude. Subsonic though, drag is not significant enough yet - and the best you can do is drop to sea level to milk every decimal of thrust the Juno can offer.

 

The heaviest plane on 1 Juno challenge (JunoSlab-51 being the winning entry there) shows that it's possible to go much heavier still. Diminishing returns, as at one point airspeeds get so low that scoring would suffer, but I think you're still a bit away from the optimum.

I decided to give it a try: USC-Z4b is a subsonic design, single 1.25m stack, one Juno, four Big-S delta wings, four strakes. I added a passenger cabin and a cargo bay with battery, probe core and panels, plus some ore (playing the part of cargo as well as helping to balance). 35 parts, 20.732t with every tank topped up. Acceleration is pretty slow, but steady - at the time I recorded its top speed it was still not done, I just got tired.

Spoiler

A single Juno powering a 20.732t reasonably aesthetic flying machine. Note I emphasized looks and function over optimization - lots of superfluous drag-inducing stuff included.

177 m/s recorded top speed 16m off the ocean surface. 112 units of LF (0.56t) used, leaving a mass total of 20.172t. Score: 177 * (20.172 / 1) = 3570.444

It flies very nicely with or without SAS, although it has a tendency to roll very slowly that I haven't been able to remove after several rebuilds. If you decide to fly it with SAS, keep an eye on pitch because the constant flutter of the control surfaces will make it slowly dip its nose.

It needs a bit more wing AoI to maintain level flight without input. If you decide to change this, the wings are attached to a cubic octagonal strut in the service bay, which is where I dialed in the rotation. And you might want to adjust authority on the various control surfaces to get responsiveness to your own taste. It's also just a tad unbalanced; as fuel is used, CoL sneaks a bit forward. All in all though it serves its purpose for an entry to this challenge.

[Box of Stardust]

Quote

The heaviest plane on 1 Juno challenge (JunoSlab-51 being the winning entry there) shows that it's possible to go much heavier still. Diminishing returns, as at one point airspeeds get so low that scoring would suffer, but I think you're still a bit away from the optimum.

You know, I was just thinking earlier today that since this challenge came up in my notifications and I already had a partial solution worked out from the top-down, I might give it a go.

But it seems you're in the same seat I was in with JunoSlab for its challenge; already on the road to final optimization. I was also thinking perhaps a ~25t craft going at a decent speed would have enough lift to get up and still enough TWR to accelerate decently enough to get to the highest point on the curve for a mass-velocity balance, but it seems you're well on the way to that already.

... Still might give it a go anyways. I like building "theory craft".

 

[swjr-swis]

On 1/20/2020 at 12:41 PM, Laie said:

any suggestions for a better scoring system, by the way?

21 hours ago, Aetharan said:

I have a proposal for a scoring-system.

 

Looks like the forum ate the reply I tried to post on this last night. It was of course a completely brilliant dissertation with iron-clad argumentation on a perfect scoring system for functional and aesthetically pleasing speedrecord-breaking aeroplanes... but alas, the napkin I wrote it on is lost forever. What I still remember:

• @Aetharan, I like some of the things you propose and hope we can find a way to include them in the scoring. That said:
  • I do think your proposal is a tad too complicated. I don't mind math, but it might discourage entrants. If you need more time to calculate the score than to build/fly a candidate plane, we've gone too far. People might just plonk down a few pics and leave it to the host or others to do the scoring. Either way, it would become not fun.
  • I welcome the idea of including factors of functionality, but I feel this challenge should remain, as @Lisias says, mainly about top speed. Any other factors, even combined, should have less impact on the score than speed itself. Just an opinion of course.
• We want to encourage 'actual planes'. Many of the requirements mentioned so far could simply be part of the challenge rules/requirements of entry: things that are mandatory and should be in the design to even compete. If defined clearly in the rules, they don't need to factor in the scoring at all. Requiring proof of landing intact might be one of them. Linking to the craft file so anyone can verify the entry if so inclined.
• Smaller number of engines should be favoured in the scoring somehow. Engine number as a divisor seems too harsh a punishment though - if anyone wishes to enter a huge jumbojet replica using only Junos, and it happens to fly fast, I would love to see it get a proper score. Still not really sure how to factor this in though. May be as simple as detracting number of engines from the score total? It should really just be a sort of tie breaker.
• While I do like long-range planes, and Junos certainly lend themselves to this, I don't agree with making it equally important as speed. It's also not trivial to establish range accurately: F3 tends to give unreliable numbers, mods have been proven to differ in their calculations in other challenges, approximations of the type 'cruise speed * (fuel / fuel consumption)' depend on other variables (SAS y/n, trim, cruising altitude, etc), and simply flying until flame out will quickly  grow tedious for longer ranges. So not really sure how to get this in. Maybe a single +100 points if it can circumnavigate? (post pictorial proof of success).
• Passenger count is a nice thought, same as cargo, but I'd rather see this calculated though categories: Eg. +10 poins for 1-5 passengers, +20 for 5-15, etc, with some maximum category to avoid spam tactics.

Time's up for today, work beckons and I need to fit in a bit of sleep.

 

[Lisias]

On 1/21/2020 at 9:01 AM, Laie said:

As a generic experience from previous challenges, I'm wary of using too many ingredients. It confuses participants, possibly to the degree of acting as deterrent, and increases the likelihood of asking for the wrong optimization by mistake.

I think this thread can help on this problem.

EDIT: if anyone is interested, the new release is calculating correctly the Score. I think it can be pretty useful on the work to trimming the craft.

Spoiler

Click the image for more.

 

Edited January 24, 2020 by Lisias
EDIT: new release for the thing. This is my final word about it here.

[Zeiss Ikon]

Well, since the scoring hasn't been changed yet (wait, I haven't looked back at top of thread yet, maybe it has -- I'll check after posting), here's this.  It's actually slower than Fleetfoot III econ -- but it's heavier and has one fewer engine, so I think it'll score better.  Let's see...

Got rid of the, um, "hippy" fuselage transitions.  Now it's just Mk. 1 and the side engines are in Mk. 0 stuck on the sides of the tail cone.  OUGHT to be less draggy -- and I think it is.  I could never get the three-engine version of Fleetfoot III to break through 350 m/s without diving, or stay there afterward.  This one will cruise right up to it (though I still haven't gotten into the "sweet spot" above 380 m/s and managed to stay there).  I did play with fuel distribution once I'd burned off enough to do so, to move the CoM a little further back and reduce the lift required from the canard, which helped a little more.

So, that's 355.9 m/s at 10.8 T on only three engines.  And I just noticed, that was in a slight climb.  Score ought to be  1281, which is another small increment over my previous supersonic class attempts.

I find I start losing both thrust and lift around 8000 m altitude, to the point I have trouble holding level flight (takes a 10 degree AoA at 180+ m/s to hold altitude).  Diving from there can get me close to 400 m/s, but I can't pull out gently enough to keep from dropping down into the drag bucket again, and wind up back down around 360 m/s and that bleeds off due to drag.  Sigh...

[swjr-swis]

It's been quiet for a few days. Let's stir this pot a bit.

How about a 'draggy' Mk3 entry? Presenting the USC-F1, scoring 663.5 m/s * ( 17.145t / 5 junos) = 2275.142. Currently runner up in the supersonic category.

It uses oxidizer for balance and as stand-in for cargo. With deployment at 12, it cruises at 4.5km and just under Mach 2 for a very decent range.

Spoiler

 

[swjr-swis]

12 hours ago, Zeiss Ikon said:

Diving from there can get me close to 400 m/s, but I can't pull out gently enough to keep from dropping down into the drag bucket again, and wind up back down around 360 m/s and that bleeds off due to drag.  Sigh...

Those FAT-455 tail fins you're using as wings are holding your plane down in that region. They're too draggy, even at absolute minimal AoI or deployment settings. I managed 365 m/s after a lot of tweaking, and it was still too far from punching through.

With the exact same body, I switched those tail fins for Big-S elevon 2, and without any further optimization it shot through to Mach 1.7, without need for diving, reaching a top around 628 m/s. That would score your plane a good thousand points more.

[Zeiss Ikon]

Thanks, @swjr-swis -- I'll give that a try.  Though by now I'm working on Fleetfoot V.  Among other things, I've dumped the tail fins for wings, gone back to "Swept Wings" which have worked well in another save (though that one has FAR, so what works may not transfer well).

[Laie]

As you may have guessed, I've been pretty busy all week, hence the silence.

The scoring discussion seems to have gone nowhere, while people keep submitting entries under the original scheme. Let's stick with it -- I'll probably have to update the thread title or something to make it absolutely clear that this isn't strictly about the fastest plane.

I'm halfways confident that the TWR-based scoring still is fair in the sense that a better-scoring plane ought to have better aerodynamics. So that, "all things being equal", the better scoring plane ought to be able and go faster than the lower scoring one, simply by removing ballast to bring them to the same TWR. All things are never equal, of course, but hey.

I will reserve the right to draw up new categories as I see fit. Variable incidence really seems to be a class of it's own, for example.

OK, moving on to updating the OP with this week's crop...

Edited January 25, 2020 by Laie

[Laie]

Not much time left today, but perhaps I can just leave this here.

I'm afraid that ore ballast is just too friggin good in terms of mass per drag.

[swjr-swis]

3 hours ago, Laie said:

I'm afraid that ore ballast is just too friggin good in terms of mass per drag.

Your challenge, your rules. I'm fine with that invalidating most of my current entries.

But keep in mind that prohibiting ore tanks will just start an arms race of sorts, finding the next best heaviest part to add to the craft. And it's trivial to add near-infinite density mass at minimal drag penalty by using bays or fairings.

The real problem is not the ore's low drag; it's that the scoring formula offers:

1. marginal benefit from optimizing for top speed, which is hard. (Even disregarding the high penalty on engine count, max speed will never exceed 820 m/s. That offers only a potential maximum 26.5% of improvement over the fastest entry so far.)
2. a very significant benefit from maximizing weight to engine ratio, which is relatively easy. (As shown by JunoSlab-51, it can potentially go as high as 51t per Juno. Heaviest ratio entry up to now was 20-ish t per Juno, so there's theoretically still up to 155% scoring improvement possible. Very likely less, but still a whole lot more than speed optimization offers.)

Given the above, you can expect anyone seriously entering for a top score to be optimizing for the high mass factor, one way or another.

[Lisias]

3 hours ago, Laie said:

I'm afraid that ore ballast is just too friggin good in terms of mass per drag.

Yep!

Score: 1575.4 for the subsonic class.

 

10 minutes ago, swjr-swis said:

But keep in mind that prohibiting ore tanks will just start an arms race of sorts, finding the next best heaviest part to add to the craft. And it's trivial to add near-infinite density mass at minimal drag penalty by using bays or fairings.

Yep**2!

 

11 minutes ago, swjr-swis said:

Given the above, you can expect anyone seriously entering for a top score to be optimizing for the high mass factor, one way or another.

Yep**3!

[Pds314]

On 1/20/2020 at 2:42 AM, Laie said:

Is that what's euphemistically called "linear construction techniques"? I'm not sure I'm fine with that.

Yes. No forward-facing nodes even if it looks like it. Reasonable? Eh.... highly errordynamic? You bet it is.

[Laie]

On 1/25/2020 at 11:39 PM, swjr-swis said:

Your challenge, your rules. I'm fine with that invalidating most of my current entries.

Pffft. No way. (edit: seems as if that came over wrong. That was supposed to mean "no way I'm going to invalidate your entries".)

At worst I'll make another category for ore tanks - when and if there's so many entries that it makes sense to do so. For the time being, I'll just point it out if someone doesn't use ballast. Already did that with Lisias yesterday, who so far is the only one to hold that distinction.

I was, however, quite surprised to learn that ore tanks don't simply hold more mass at the same form factor, but are significantly less draggy than any other Mk1 fuselage of similar length.

So, let me show you.... first, a variable-incidence passenger plane:

...and the "same" plane with ore ballast instead of crew cabins:

Not only does the latter go a little faster at considerably more weight, it also goes supersonic without any ado. While the passenger plane had first had to climb to 6km, and then do a shallow dive to 4km.

That's 590m/s, 10.974t -> 2158 for the passenger plane,
and 600m/s, 12.163t --> 2432 for the one carrying ore ballast.

Edited January 27, 2020 by Laie

[purpleivan]

Didn't notice the "no ballast tanks" before taking a leaf out of @Lisias book and slapping something together that uses them.

Went for the single Juno to get more out of it score wise (if it was a valid one that is). Hellish to get into the air, It only started climbing once it had dropped below runway level, in the run down to the beach, clearing the sea by a couple metres.

8 tons at 253m/s on a single Juno would have given it a score of 2024, if it didn't rely on the use of forbiden bits.