Maneuver node off by 200 m/s?

[Archgeek]

On 2/2/2018 at 4:29 PM, Brainlord Mesomorph said:

Spoiler

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The Olympus Interplanetary Coloniation Cruiser: Seen departing the Hephestus Spacedocks, Over a kilometer long, half a kilometer tall, and 3/4 of a kilometer wide, 950 tonnes. She carries 6 assorted nuclear landers, has two labs, large scale ISRU facilities and room for 44 Kerbal colonists plus crew. AND  can carry 120 tonnes of additional payload anywhere in the solar system.

Are you...sure about those size numbers?  Unless you've pretty severely tweakscaled those parts, I'd say you're looking at around 100m+ stem to stern, ~770m beam, and 50m tall.  That's just my instinct based on those gigantors and the orange tank in the drydock there.

So, I decided to do some picture math using paint's line tool read-out, Pythagoras of Samos, and calc.exe.  Drawing little lines on the orange tank in the background (ignoring perspective to give an inflated length) and the large docking port visible on the tall part of the ship for less of a perspective hit, I take the rise and run Paint displays, square 'em, add 'em, take the square root of that, and I get about 13.6 pixels across for the orange tank and 14.14 pixels for the docking port.  Doing the same for the length and height of the beast, I get 591.85px and 242px.  This already looks about an order of magnitude off.  Then I divide and get a length that must be less than 43.5 size2 diameters long, and a height of roughly 17.11 size2 diameters.  I think a large docking port and an orange tank are 2.5m wide, so that's possibly ~42.8m high by something less than 108.8m long.

Big ol' impressive ship, but not a klick-long monstrosity.

[Brainlord Mesomorph]

1 hour ago, Archgeek said:

Are you...sure about those size numbers?  

how embarrassing, yes, I'm off by a factor of 10.

There's a decimal in the dimensions in the Engineer's Report I didn't notice.  (I just looked) The assembled mockup is bigger that either the VAB or the SPH.  (I guess that makes the size of the Mk1 cockpit and crew pod ridiculously small) 

You could have just asked, I would have double checked.

[Leafbaron]

2 hours ago, Archgeek said:

Are you...sure about those size numbers?  Unless you've pretty severely tweakscaled those parts, I'd say you're looking at around 100m+ stem to stern, ~770m beam, and 50m tall.  That's just my instinct based on those gigantors and the orange tank in the drydock there.

So, I decided to do some picture math using paint's line tool read-out, Pythagoras of Samos, and calc.exe.  Drawing little lines on the orange tank in the background (ignoring perspective to give an inflated length) and the large docking port visible on the tall part of the ship for less of a perspective hit, I take the rise and run Paint displays, square 'em, add 'em, take the square root of that, and I get about 13.6 pixels across for the orange tank and 14.14 pixels for the docking port.  Doing the same for the length and height of the beast, I get 591.85px and 242px.  This already looks about an order of magnitude off.  Then I divide and get a length that must be less than 43.5 size2 diameters long, and a height of roughly 17.11 size2 diameters.  I think a large docking port and an orange tank are 2.5m wide, so that's possibly ~42.8m high by something less than 108.8m long.

Big ol' impressive ship, but not a klick-long monstrosity.

loveing savage bro. 

[qzgy]

28 minutes ago, Archgeek said:

Big ol' impressive ship, but not a klick-long monstrosity.

Have to agree with you there. Running rough approximations, the ship is about 43 times the length of the Mk3 cargo bay, which when multipled by the 2.5 m length of it only comes to about 110 m and that's being generous. Also your assumption of ornage tanks and large doing ports being 2.5 m wide is correct.

[Archgeek]

2 hours ago, Brainlord Mesomorph said:

how embarrassing, yes, I'm off by a factor of 10.

There's a decimal in the dimensions in the Engineer's Report I didn't notice.  (I just looked) The assembled mockup is bigger that either the VAB or the SPH.  (I guess that makes the size of the Mk1 cockpit and crew pod ridiculously small) 

You could have just asked, I would have double checked.

Oops, sorry!  I didn't mean to embarass -- I was genuinely unsure if tweakscale was involved or not.  That and I couldn't resist the urge to spend my lunch break doing a bunch of silly math.  

[KerikBalm]

Also, you can't just add the numbers from your retro burn to the excess from the maneuver node. By the time you start the retro burn, you are far from PE 150 m/s several minutes after pe on a highly elliptical orbit translates to a much lower amount of dV if corrected at PE.

Also the maneuver calculator can be a bit weird when burning far from the node. You can spend 200 m/s while the remaining dV for the maneuver, according to the maneuver node display, may decrease by less than 200 m/s.

My guess is that you spent more dV than you thought, and over estimated your dV excess.