Parts & Vessels Drag on contents of cargo/payload bays (Do not occlude drag)

[Anonymous Bug Reporter]

Reported Version: v0.1.5 (latest) | Mods: none | Can replicate without mods? Yes 
OS: Windows 10 | CPU: amd ryzen 7 3800x3d | GPU: AMD RX 7900XT | RAM: 64 GB DDR5 @6000MHz

 

Parts inside of the mk2 cargo bay seem to experience drag. There are 2 craft files attached to this report, one with a cargo bay with a light payload, and one with the cargo bay replaced with a short fuel tank of greater mass. The craft with the payload bay has significantly greater drag than the craft without a payload bay, as evidenced by the fact that it cannot reach a speed greater than 370 m/s, where as the craft without the bay is easily able to push past that speed and reach orbit, despite being heavier with the same external geometry. 

 

Included Attachments:

SateliteTest1.json

TestVehiclenopayload.json

Edited March 30 by Spicat

[Anonymous Bug Reporter]

Reported Version: v0.2.0 (latest) | Mods: Alarm Clock (AlarmClock 1.2.1) BepInEx (BepInEx 1:1.8.1) Community Fixes (CommunityFixes 0.11.0) Flight Plan (FlightPlan 0.9.1) K2-D2 (K2D2 v0.11.2) KerbalHeadlamp (KerbalHeadlamp 0.1.2) Maneuver | Can replicate without mods? Yes 
OS: Windows 11 | CPU: Intel(R) Core(TM) i5-8250U CPU @ 1.80GHz | GPU: NVIDIA GeForce GTX 1660 Ti | RAM: 65390 MB

I've built a SSTO which goes to orbit quite easily with an empty cargo hold. However, if a package consisting of 1x Fl-R25, 3x Z-200, 6x Z-400, 1x SP-4L, 1x Communotron DTS-M1 and 1x SRW-125 is fitted in the cargo bay, it only reaches orbit with great difficulty. The mass of the cargo isn't the issue, I've replaced the cargo with a fuel tank with a similar mass and orbit is still easily attainable with this swap place. The Micro engineer mod, shows significant difference in drag with and without the stowed cargo, so drag from cargo that should be shielded by the cargo bay seems to be the issue.  

Included Attachments:

SSTO.json

[Lekiffer]

This is a big problem , since the for science update the game is actually playable,   started making a space station, i wanted to just use an SSTO because its better for the environment , but there was one module (lighter than some of the others) that was experiencing so much drag its next to impossible to take off the ground and when you do get off the ground it instantly backflips . Its nothing to do with the aerodynamic to weight position , nor is it where the wheels are placed in relation to the weight to get a good rotation because the SSTO performs very efficiently empty , and with parts stowed inside that do not experience much drag.

In the end i had to launch that module by rocket which defeated the whole purpose of what i was trying to achieve. 

I hope its an easy fix , literally spent hours  and hours  getting the balance just to find out the cargo bay doesnt actually work, iv noticed this on the XL cargo bay and also the Medium size cargo bay so i imagine it affects all of them.

 

[PilotWasHere]

Reported Version: v0.2.1 (latest) | Mods: none | Can replicate without mods? Yes 
OS: Windows 10 | CPU: AMD Ryzen 7 5700X 8-Core | GPU: AMD Radeon RX 6700 XT | RAM: 32Gb

 

Bug is pretty much as simple as the title states, when building craft with payloadbays, parts placed inside them will cause drag on the craft preventing it from performing as expected, most noticeable on spaceplane type craft. To reproduce, construct a craft that is capable of achieving supersonic flight with a payload bay and nothing inside it, take note of drag forces using the cheat menu aero gui, or the craft's top speed, then place a part or parts inside the payloadbay and test again, drag forces increase and max speed decreases despite unaerodynamic parts being occluded by the craft's fuselage and payloadbay doors.

I will provide a craft file that demonstrates this issue as well, the craft provided cannot exceed 360m/s easily as provided, but removing the payloadbay contents by disconnecting the monopropellant tank they're rooted to will have the craft reaching orbit with 1000m/s dv left in its fueltanks.

 

Included Attachments:

PilotPayloadBayTestCraft.json

Edited March 30 by Anth
Changed to a json file

[Spicat]

@PilotWasHere, merged your bug report.

[Kayser]

I noticed this bug when trying to make efficient and nice designs of SSTO with all science equipment. It effectively made me lose interest in the challenge, since it effectively makes it impossible to build a low drag craft with all the science equipment on it, because wherever you place it, it causes a lot of drag and makes the plane very fuel inefficient.

[stephensmat]

I'm kinda wondering if this is  part of the problem I'm having with Spaceplanes.