UAV Belly Landing Loads?

[WK95]

I'm a student working on designing a UAV and I'm currently working on figuring out preliminary estimates for most structural loads. I'm looking for reference for the load factors experienced by UAVs designed to belly land.

Examples of UAVs that belly land are the Lockheed Martin Stalker, and the Thales Spy'Ranger. I'm ignoring UAVs where the airframe is designed to separate on impact such as the RQ-11 Raven since I'm not expecting mine to do that.

Referencing another forum thread (

http://www.eng-tips.com/viewthread.cfm?qid=367609),

16G is one design value for hard landings. The load factor may be from 20-40Gs on a crash. However, this thread assumes the UAVs has landing gears.

In the case of belly landing UAVs, what are common design landing load factors?

 

[IRstuff]

Kind of depends on what you're landing on, doesn't it?
Is this a fixed wing UAV?

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[WK95]

Well, I've only heard of the term belly landing being used in reference to fixed wing aircraft. But yes, it is fixed wing as are the Stalker and Spu'Rangers.

Let's say the landing is on dirt (soft at it's best and packed at it's worst).

For the Spy'Ranger , referring to time 1:07 in the video

https://www.youtube.com/watch?v=lZGyva_2pIk,

the UAV is seen landing on it's belly in dirt.

I'm interested in the loads in such a landing.

 

[berkshire]

If you are designing a UAV with no landing gear , You would do well to research old gliders , which used a drop off dolly for take off and landed on a skid ,or reinforced belly.
B.E.

You are judged not by what you know, but by what you can do.

 

[WKTaylor]

WK95...

Hmmmmmmm... similarities to seaplanes and water-landings...?

MIL-A-8864 AIRPLANE STRENGTH AND RIGIDITY - WATER AND HANDLING LOADS FOR SEAPLANES

SAE/TP 2011-01-2696 Seaplane Conceptual Design

Regards, Wil Taylor

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[WK95]

Hmm. That's an interesting way to look at things. Thanks for the suggestion.