David Robinson/543 7/18/08

1. Atlas Truss Adapter & Launch Vehicle Details(all I can find in the Atlas Mission Planner’s Guide and Standard Interface Spec) David Robinson/543 7/18/08

5. 173 inch (4.4 m) “Truss” Payload Adapter

6. Published Performances [kg] for C3 = -0.5

7. Specific Atlas-V 551 Performance for IXO • Atlas V 551 performance to the nominal IXO 700,000 km L2 orbit (at C3 = -0.5 kg²/s²) is 6305.0 kg • The payload penalty for using the 5m x 26.5m Long Fairing is approximately 85 kg • The performance loss equals 10% of the fairings’ mass difference, reflecting the fact that fairings are jettisoned at a low altitude per (NLS) S. Good AI Solutions, 2006

8. Received 7/23/08

10. David, I returned from vacation this week finding a number of emails which started with yours below. The 4394 PL truss referenced in the Mission Planner's Guide was designed for a specific mission and never flown. The interface to the Centaur for this truss is at a 123" dia BC which makes it a conical-shaped truss. The payload capability for this truss is limited by the capability of the Centaur Forward Adapter (CFA) to which it mounts, and since the truss is conical it imparts a component of its load radially into the CFA. For this truss, we created capability curves of mass vs. cg for the conservative load factors referenced in the Mission Planner's Guide. From your email below I infer that your SV is large, but without knowing the weight or cg location I cannot tell whether the 4394 truss adapter is the one that will work for you. A better choice might be another truss which we designed for a different payload. That truss is ~132" dia at the top and therefore is more cylindrical, and the loading into the CFA is axial. The capability of the CFA is much higher with primarily axial loading. I can send you jpegs of Pro/E models, sketches or STEP files of either truss. I could also send capability curves, or you could tell us what you expect the approximate mass and cg to be. Let me know what will work best for you. Thanks, Mike Dew (303) 269-6377 Received 6/25/08

11. David, here are the answers to your questions. Please let us know if you need any more information.Thanks,Cathy_____________________________ Cathy Andrulis United Launch Alliance Payload Accommodation Structures 303-269-6402 NEW 888-981-0364 pager 303-269-6272 FAX NEW · Bolt hole pattern of the 4,394 adapter to the spacecraft This is documented in the Standard Interface Specification (SIS) Figure 4. Please let us knowif you need a copy of this document. · Position of the payload envelope relative to the SIP (standard interface plane) of the truss. Con-X is a tall spacecraft which may use the 5m medium or large fairing. The spacecraft goes well up into the ogive section of the fairing and so I need to be sure I understand where the payload envelope of the fairing “begins”. See figures 4.1.1-4 and 4.1.2.1-1. The 4394 truss is 46" high. This adds an additional approximately 21" to the payload envelope height. (The 300.45" dimension becomes 321" for the 5m medium.) The 3302 truss is 36" high. This adds an additional approximately 31" to the envelope height. (The 300.45" dimension becomes 331" for the 5m medium.) · Some words about the separation system. Is it a set of hard points (18?) with explosive bolts and push-off springs? It could be. The separation system could also be a clampband or frangible joint, depending on the need of the SV.Please note that this separation system will be within the payload envelope. · We assume there is no CG height limitation or envelope with these truss adapters… is this correct? There is a CG height limitation. The 4394 truss is capable of carrying 13,500lb with a cg height of 225". The 3302 truss is capable of carrying 42,000lb at 225". The full 3302 truss capability is shown in the SIS Figure 10(the HPC curve). · Figure 2.5.6-1 says that there is a 213 kg launch vehicle performance penalty for using a truss adapter. Is this essentially the weight of the 4394 adapter and if we used a smaller one like the 3302 size would the weight penalty be less? Yes. The weight of the 3302 truss is approximately 428lb. Received 6/26/08

12. 7/21/08 telecon with KSC with Cheryl Malloy, et al. They advised using this CG Height chart from the “SIS” document. Use the “HPC” line since it represents the truss adapter. Also per Cathy Andrulis United Launch Alliance 6/26/08. Atlas 5 Standard Interface Specification document

13. Payload CG Height Limits

14. (email from Jeff S. 2006 10 03) Gabe,         We were unofficially told (and they would never put it on writing) that both the Atlas V and the Delta IV using the 173" truss PAF could handle a CG almost as high as the fairings themselves. An email that I had George Roach send me a couple years ago which was the closest thing we ever got in writing on this matter.  It was more than 6 years ago that I asked the launch vehicle folks @ KSC and they said this was the case but that they could not put it in writing. Regards,Jeff Use “Truss” Adapter for no CG Height Limit Baselining the 4.4m “Truss” Payload Adapter relieves IXO from any Center of Gravity height limitations