1 about this model this model employs 3 inverted ‘bipods’ for baffle. bipods in quotes because...

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About this modelAbout this model

• This model employs 3 inverted ‘bipods’ for baffle. Bipods in quotes because legs are not pinned at ends, but are fixed-fixed.

• No skins are included in the FEA, but are certainly necessary for contamination and light control...skins would carry loads in FEA, and I want to show the structure is adequate w/o them.

• In FEA, instrument deck/lower closeout is modeled as aluminum/honeycomb sandwich with 1mm skins and 25mm core, not populated with instrument electronics in FEA.

— Not sure how exactly this would integrate with the 12-sided angle aluminum structure that forms the interface between baffle and s/c.

— Boxes carried on deck should be pushed as far toward perimeter as possible.

• A similar model with 5 inverted ‘bipods’ was analyzed.— Different material thicknesses from this model.— Basically copy the struts from this model, clocked 60 degrees, omit a pair by

instrument.— 5 bipod model is 16kg lighter than 3 bipod model.

• 5 bipod natural frequencies: 18.4, 21.0 Hz.• 3 bipod natural frequencies: 18.7, 19.2 Hz.• At Delta IV launch accelerations, mat’l safety factors are 10 in aluminum and 5

in Ti thermal standoffs.

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Model specifics (see slide 7)Model specifics (see slide 7)

• Inst deck/baffle bottom closeout: 1mm Al skins on 25mm thick Al honeycomb core.

• S/C adapter/handling ring: Aluminum angle, 150mm x 75mm, longer leg of angle is 3mm thick, shorter leg is 5mm thick.

• Thermal standoffs, 50mm dia, 1.5mm thick Ti tubes.

• Baffle support legs: closed rectangular sections, ~110mm x ~50mm, 3mm thick walls.

• Stiffening gussets in angle near thml standoffs: 5mm thick Aluminum.

• Flange at base of upper baffle: 5mm thick.

• Bottom 200mm of upper baffle tube: 3mm thick.

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Observatory, dummy OTAObservatory, dummy OTA

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Lower baffle area, no skins in modelLower baffle area, no skins in model

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Array turned offArray turned off

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inst deck/bottom closeout

1.5mm thick Ti thermal break3mm thick, 150mm tall part of angle

5mm thick, 75mm wide part of angle

5mm thick gusset 110mm x 50mm x 3mm legs

5mm thick upper baffle flange

3mm thick bottom 200mm of upper baffle

1mm thick nominal

upper baffle

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Inst. deck/lower closeout turned offInst. deck/lower closeout turned off

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OTA turned offOTA turned off

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Angle web turned offAngle web turned off

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Just baffle support legsJust baffle support legs

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‘‘detail’ viewdetail’ view

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inst deck turned offinst deck turned off

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