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  1. hombre

    Crash Loads For Military Aircraft

    I've used the 100G load factor for vibrations as well. There is a chart out there (Miner's?) that shows load factor vs. weight for dynamic loading. 100G's corresponds to equipment between 1 and 5 pounds. The load factor reduces linearly as the weight is increased. This was only used for...
  2. hombre

    RAC Structures Manual

    This is probably an in-house Raytheon Document (RAC - Raytheon Aircraft Company) similar to the Boeing Design Manuals (BDM's) 6000 Series. These documents show analysis methods that are approved and able to be referenced in certification documentation. Unless you know someone who has worked at...
  3. hombre

    Currey's Landing Gear Book Leaf Spring Design Help

    Hi Drkwing, What specifically is your question? After looking at the deflection equation, little 'e' should be capital 'E' for the material modulus of elasticity. Also, P1 is not defined, but appears to be P1=Pcos(theta). The strength equation is nothing more than flat plate bending at the...
  4. hombre

    Boeing BACB30US14 Specification

    You're right... I stand corrected. Hombre
  5. hombre

    Boeing BACB30US14 Specification

    The "14" is the bolt diameter in 32nd's. Therefore, the diameter is 7/16. The "24" is the grip length in 16th's. Therefore, the grip is 1.5 inches. I don't remember the significance of the "M", either. Hombre
  6. hombre

    Cabin cross section dimensions info?

    If you do not have access to the aircraft technical manuals such as SRM, MM, etc., Jane's All the World's Aircraft is an invaluable source for this type of information. Hombre
  7. hombre

    Joggled Skin Repair Doubler

    If you joggle an internal repair doubler up and over a stringer and pick up the existing stringer fasteners, are these fasteners ineffective? Bruhn discusses joggled members, i.e. angles, and says a general rule of thumb is not to allow any axial load across the joggle. The required balancing...
  8. hombre

    Repair Strap Inter-rivet Buckling Calculation

    Just thought I would get my two cents worth in... we use flat fail safe straps on the upper chord of many different types of beams to carry the compression loads. I do not believe crippling applies in this case. Therefore, the allowable is the lower of Fcy or Fir. Hombre
  9. hombre

    FEMAP display question

    You might check to make sure that you have not inadvertently modeled your constraints in a different group or layer than the ones you are currently displaying. Also, check to make sure that the constraints are included in the current load set that you are displaying. This applies to displaying...
  10. hombre

    ELFORCE in Nastran

    He is saying that the force output from NASTRAN for 2D elements is force per unit length (lbs/in for example). Therefore, you need to multiply the elemental force by the element length. Hombre
  11. hombre

    ELFORCE in Nastran

    jsboy, The ELFORCE (or FORCE) card generates the nodal forces at the four corners of the 2 dimensional element and/or at the center of the element. If CENTER is specified, only the force at the center is output which is the average of the nodal forces at the corners of the element...
  12. hombre

    Web repair design

    Alex, In regards to 2), it may be necessary to include a portion of the web to show the cap good. For instance, a very high compression load. In this case it is justifiable to include an effective width of web based on the crippling allowable with one end fixed and one end free. For example...
  13. hombre

    Why the references to cards & decks?

    Good point... however, the use of cards and decks bring organization to the "lines" of code. It would be very difficult to debug lines of code (which are nothing more than numbers in most cases)! Therefore, it is much easier (for my brain, anyway) to think of all the bulk data entries as cards...
  14. hombre

    Moment of Inertia

    Some clarification is needed... are you wanting the area moments of inertia for stiffness calculations or the mass moments of inertia for structural dynamics calcs? Area moments may be calculated as outlined in Bruhn's Analysis and Design of Flight Vehicle Structures. Essentially, the area and...
  15. hombre

    Aircraft Fastener Properties?

    Grant, Look in Chapter 8 of MIL-HDBK-5 under threaded fasteners. The shear and tension allowables are based on the shear and tensile stress of the fastener, respectively. For example, the AN3 bolts are 95 ksi shear and 125 ksi tension. Therefore, the allowable shear load is 2690 lbs. and the...
  16. hombre

    Lift and Drag Coefficient

    The best resource (and a book all aero's should own) is Theory of Wing Sections by Abbott and von Doenhoff. This book has all kinds of the information on NACA airfoils. Hombre
  17. hombre

    Mathematical Solution Theory on FEM

    Don't forget about Finite Element Procedures by Bathe and Finite Elements: Their Design and Performance by MacNeal (of MSC fame)! Hombre
  18. hombre

    Cherrymax Unisink Head Rivet Strength Allowables

    I don't have this information, either. However, I believe based on the thickness of your material, you are going to be bearing critical anyway. It does not matter what the strength of the rivet is because the material itself is going to fail. Hombre
  19. hombre

    How do MSC Nastran, nx Nastran, and NE Nastran compare?

    In my opinion, MSC/NASTRAN with PATRAN is the best package. I have used MSC/NASTRAN with FEMAP and have evaluated NE/NASTRAN with FEMAP for my previous employers. While NE/NASTRAN is a very strong package, it does not have all of the advanced capabilities that MSC has due to its relative...
  20. hombre

    Solidworks to design aircraft structure?

    We are using Solidworks to design modifications for Learjets, King Airs, etc. I have had most success in using it to model the parts, assemblies, and installations. I use Autocad to make drawings, however. The Solidworks drawings are much too cumbersome even though they retain all...

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