Crash Loads For Military Aircraft

[alexeu]

To all who have analysed or certified antenna installations in the Radome area, what are the typical crash load factors that were used? Is there also any references that defines those crash load factors?

Regards
AEU

 

[rb1957]

we generally use the FARs ... 9g fwd, 3g side, aft is almost never an issue (and is generally covered by inspection), up/down is generally driven by ultimate flight maneouvres

 

[CRACKKILZ]

Depending upon the type of antenna you are planning to use (long blade vrs flat etc) there are a couple of other design cases you may want to consider.

1. 100 Gs applied in the up, fwd and lateral directions to account for vibrations.

2. A hand load (abuse load) of 300 Lbs in all directions.

Crash loads typically are not critical when compared to the above.

 

[alexeu]

Crackkilz, 100G seems a lot to be applied for a load factor. Do you have a reference for the 100G load factor or is that a guideline that you have been using?

rb1957, the FAR crash loads were exactly what I had in mind. But I was thinking of other load factors which might be more critical.

I had used a 12.5G down for the design of an airstairs for an European military aircraft.

Thanks anyway guys. Any other inputs will be appreciated.

 

[rb1957]

i like crackkilz's comments ... it's in line with what we do ... i got hung up on "crash" loads.

100g is a pretty common static equilvalent of dynamic loads, if you think you've got vibration loads.

300 lbs is the top end of static (ultimate) loads fro ground handling, we use 200 lbs, in the end wahtever you're comfortable with ! ... the idea being to ensure the structure should survive in-service loads

 

[hombre]

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 preliminary sizing until the environment of the aircraft was determined.

Hombre

 

[CRACKKILZ]

alexeu

The 100Gs and 300 pounds was a Boeing recommendation for a project I was involved with several years ago.

I think it is pretty much an industry standard now.