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Old 07-05-2018, 02:16 PM   #901
vicky_molokh
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Default Re: GURPS Spaceships Design Spreadsheet

Quote:
Originally Posted by ericbsmith View Post
It's been a while since I wrote up the stats for those, but I believe I based costs loosely on Vehicles 2e while I based top speed on real-world vehicles. Hovercraft are not particularly streamlined and suffer greatly from drag from their ground-effect envelope combined with the fact that they operate at ground/sea level instead of being able to gain altitude and operate in thinner air with less drag.
I'm comparing two unstreamlined SM+3½ craft, so it doesn't seem like the bad streamlining is the reason:
Skirt $6k + Ducted Fan $24k + two reactors (minimum for overground hoverflight), giving Move 3/30.
vs.
Helicopter rotor $20k + one reactor, giving Move 5/40.

Doesn't the ground effect increase efficiency of thrust relative to a 'naked' propeller, leaving more power available for horizontal thrust?

Also, ground speed three times higher than water speed, is that right?
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Last edited by vicky_molokh; 07-05-2018 at 02:47 PM.
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Old 07-05-2018, 03:48 PM   #902
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Default Re: GURPS Spaceships Design Spreadsheet

Quote:
Originally Posted by vicky_molokh View Post
Doesn't the ground effect increase efficiency of thrust relative to a 'naked' propeller, leaving more power available for horizontal thrust?

Also, ground speed three times higher than water speed, is that right?
The primary advantage of the ground effect skirt is to increase stability, which helicopters and VTOL Jets have issues with when they get close to the ground or water (the backblast off of the ground causes vortices which make it difficult to control). The Hovercraft speed record is only 85mph on water and 56mph on land (this is, literally, where I got the max speeds from for the Hovercraft in the Optional Rules page); hovercraft are never going to have speeds, or general stats, comparable to Helicopters.

Now, I'll have to look into the actual speeds listed, because I don't think that's right, especially with ground speed being greater than water speed.
Edit: And it looks like I accidently multiplied Hovercraft Ground Speed by x4 across the board (actually, in the formula I doubled it instead of halving it like Water Speed).
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Last edited by ericbsmith; 07-05-2018 at 04:11 PM.
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Old 07-05-2018, 04:10 PM   #903
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Default Re: GURPS Spaceships Design Spreadsheet

Quote:
Originally Posted by ericbsmith View Post
The primary advantage of the ground effect skirt is to increase stability, which helicopters and VTOL Jets have issues with when they get close to the ground or water. The Hovercraft speed record is only 85mph on water and 56mph on land (this is, literally, where I got the max speeds from for the Hovercraft in the Optional Rules page); hovercraft are never going to have speeds, or general stats, comparable to Helicopters.

Now, I'll have to look into the actual speeds listed, because I don't think that's right, especially with ground speed being greater than water speed.
Edit: And it looks like I accidently multiplied Hovercraft Ground Speed by x4 across the board (actually, in the formula I doubled it instead of halving it like Water Speed).
Oh, I'm not saying a better top speed is warranted. I'm just puzzled by it requiring twice the number of systems and twice the number of power points to achieve its modest performance. Back before the system was added, I was thinking that a hover+propulsion system would at worst be comparable to a rotor in terms of monetary and energy costs, and I'm curious about the physics/engineering that is the cause of such gross inefficiency (after all, helicopters aren't the most elegant flight system either).
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Old 07-05-2018, 04:12 PM   #904
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Default Re: GURPS Spaceships Design Spreadsheet

Version 2.0 Release Candidate 28
-Fixed Bug where a ship with User Systems could error on loading.

Version 2.0 Release Candidate 27
-Fixed Bug preventing ships with Structural Reinforcement from loading.

Version 2.0 Release Candidate 26
-Corrected Hovercraft Ground Speed, which was accidently multiplied by x4.

You can download the spreadsheet here:

Excel 2000 (RC28)
http://gurpsland.no-ip.org/zip/SpaceshipsV2.zip (~5.3 MB)
http://gurpsland.no-ip.org/zip/SpaceshipsV2.7z (~2.7 MB)

Excel 2007 (RC28)
http://gurpsland.no-ip.org/zip/SpaceshipsV2-2007.zip (~6.6 MB)
http://gurpsland.no-ip.org/zip/SpaceshipsV2-2007.7z (~6.5 MB)

OpenOffice 3.3.0 (RC9)
http://gurpsland.no-ip.org/zip/SpaceshipsV2-Ooo.zip (~2.1 MB)
http://gurpsland.no-ip.org/zip/SpaceshipsV2-Ooo.7z (~1.9 MB)

Spaceships Optional Rules
http://gurpsland.no-ip.org/pdf/Space...ionalRules.pdf
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Last edited by ericbsmith; 08-02-2018 at 12:58 PM.
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Old 07-07-2018, 06:04 PM   #905
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Default Re: GURPS Spaceships Design Spreadsheet

Just took a look at this and I LOVE, LOVE, LOVE all the crunchy bits with built in calculators for everything. This is everything I adore about Excel. Plus, someone else did it. I am going to use this for my Rifts Robots to see how it works.

THANK YOU!
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Old 07-10-2018, 06:55 PM   #906
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Default Re: GURPS Spaceships Design Spreadsheet

Hi, I tried saving a design I made, it let me but when I tried to load it again it gave me an error message and wouldn't load. When I ran the debugging thing it seemed to single out this line of code:

TabledSTdHP.Caption = Format(CInt(ShipdSTdHP), "#,##0")

It seems to relate to the design having structural reinforcement as a system. I tried loading a different design that didn't have that and it loaded fine. Using Excel 2007 with Windows 10 btw.
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Old 07-10-2018, 07:43 PM   #907
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Default Re: GURPS Spaceships Design Spreadsheet

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Originally Posted by davester65 View Post
It seems to relate to the design having structural reinforcement as a system.
Yes, it does seem to be linked to Structural Reinforcement. I've just uploaded RC27, which corrects this loading bug. If you import the saved ships from RC26 into RC27 they will load just fine in RC27, as this bug only cropped up during the ship reading routines and not the ship saving routines.
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Old 08-01-2018, 06:27 PM   #908
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Default Re: GURPS Spaceships Design Spreadsheet

Hi, I seem to have a problem where if I save a design I made to Unofficial Ships and it has a user designed system it doesn't want to load the ship properly.

This is what it highlighted when I ran the debug thing:

For i = 1 To NEW_SYSTEM_STATS
If CDbl(ShipUserSys.Cost(i)) <> CDbl(SheetUserSys.Cost(i)) Or _
ShipUserSys.PerformanceOne(i) <> SheetUserSys.PerformanceOne(i) Or _
ShipUserSys.PerformanceTwo(i) <> SheetUserSys.PerformanceTwo(i) Or _
ShipUserSys.PerformanceThree(i) <> SheetUserSys.PerformanceThree(i) Then
UserSystemsDifferent = True


It's the excel 2007 version run on windows 10. If you need me to send all the other stuff it said let me know. I didn't think posting several pages of what looks like computer code on the forum would be a good idea.
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Old 08-01-2018, 06:33 PM   #909
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Default Re: GURPS Spaceships Design Spreadsheet

It's one of my own designs. When I saved it that's where it wanted to save it to. It's not one of the designs you put there. The ones that I made that just use official systems seem to load just fine.
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Old 08-01-2018, 06:48 PM   #910
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Default Re: GURPS Spaceships Design Spreadsheet

Yeah, I realized that after I asked (thus why I deleted my question). I'll look into this, but probably not until tomorrow.

The User Systems is an extra level of complexity from the standard systems, since the ship has to save all the data for all the SM's that are defined as well as save from and load into the User Systems sheet. The standards systems are stored as just a system name, and get all their stats as a lookup on a data table.
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