Landing Gear - Lamar 2/23/96 Progress Report

From:David Skeelsdmskeels@ih2000.net

The scope of the landing gear group for this semester is to design the STRUCTURE of the landing gear legs--basically from just above the energy dissipation systems in the footpad area to the just below the locking mechanism and hinges on the bus structure.

The construction of the landing gear structure has been tentatively changed to correspond to the bus structure, which is graphite epoxy. Use of common materials and construction techniques will reduce integration and possible functional problems between the structure and the landing gear. Graphite epoxy will reduce the weight of a structure constructed of comparable aluminum by as much as 40%. Since the mass budget for the landing gear is already so small, any gains found in construction weight savings are extremely helpful.

Autocad Drawings - David Skeels
Dimensions necessary to fully define the outer envelope of the bus structure and attachment points of the landing gear were received Tuesday, 2-20. AutoCad 3D drawings of the bus structure and preliminary landing gear have been produced, including the dimensioned leg. A copy of the Autocad file has been placed on the TSGC FTP server for retrieval by U of H for finite element analysis. The 2D AutoCad drawing used to determine the possible landing gear configurations that would fit into the launch vehicle was analyzed further to determine maximum usable landing gear envelope in the payload bay of the Delta II. Attachment at the expected upper member attachment points yields a relatively short leg, but attachment at the top of the bus structure looks like a feasible option for obtaining maximum usage of space. Ronnie Baccus at A&M needs to be contacted to determine if these attachment points can support the loading necessary during impact. We began looking into importing the AutoCad 3D line drawings into ADAMS for dynamic simulation of landing to determine the configuration of the landing gear necessary to prevent rolling over of the vehicle on impact.

Solids Modeling - David Coler & David Skeels
David Coler and I have been to the Maritime Technology Center (MTC) twice in the past 2 weeks, and are becoming familiar with Pro/Engineer. Since access to the MTC and the learning curve for Pro/Engineer is becoming an issue, the original intent to use Pro/Engineer to create a solid model for use in ADAMS and ANSYS may be changed if the AutoCad drawings generated can be imported into ADAMS for dynamic analysis. We do expect to gain access to ADAMS soon, and expect that if the AutoCad model can be imported that the time required to set up the dynamic analysis will be reduced.

Energy Dissipation Systems Performance Specifications - David Coler
Preliminary performance required by the press-fit-washers and metal foam systems has been calculated for input into the dynamic model simulation. I appears that to meet the 7.5g deceleration requirements of the bus structure, approximately 3 cm of translation (or stroking distance) will be required both in the horizontal and vertical directions in the energy dissipation systems during impact. These calculations have been verified with similar Artemis data, and are on the same order. For input into the U of H FEA model of the landing gear, an average force of 3000 lbf (13,344 N) is estimated to act over 0.2 seconds in both the horizontal and vertical directions on the structure just above the footpad during impact. Due to the type of energy dissipation systems chosen, this force is close to constant during impact.

Joints Research and Design - Ganesh Venkataramani
Some difficulty has been encountered in finding information on the design of joints to be used within the landing gear structure. Several papers from the Aerospace Mechanism Symposium will be requested from NASA JSC next week, and should be received within several days. From the titles and categorizations of the papers, they appear to contain information that will be useful. A possible design much like one used by the JSC Structures Group in the redesign of the Shuttle Orbiter seats is being considered for further development. In the event that research continues to prove futile, this design will be developed.

Next week:
* Contact A&M to discuss upper hinge attachment points * Refine AutoCad drawings based on A&M input * Continue to look into ADAMS or other dynamic simulation * Continue joint design research
* Contact Duocel (metal foam) vendor for more information

current mass: 15 kg
power: minimal-TBD