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Trade-Off Studies High-Lift System Level Design  
User currently offlineMartinKoschel From Germany, joined Jun 2002, 14 posts, RR: 0
Posted (13 years 5 months 1 week 5 days 6 hours ago) and read 3123 times:

Hi All,

just started preparing to write a diploma thesis. The topic will be something on coming up with a guideline on how to apply trade-off studies in high-lift system level design. Its scope shall include technical as well as economic aspects.
Is anyone of you guys aware of papers/literature/whatever documents related to that? Especially on methodology of trade-off studies in aerospace engineering?
I already searched the internet (NASA, AIAA, ....) but I was not really successful (Maybe I searched for the wrong keywords and/or in the wrong place  Insane)

I'd be glad to receive any hint on that. (No highly confidential proprietary stuff - that would violate the forum rules)
Thanks a lot to all who help me out on that one.  Smile/happy/getting dizzy


ps. if anyone prefers not to answer this in the forum, you are welcome to reply to my private email (see profile). Thx.

10 replies: All unread, jump to last
User currently offlineZionstrat From United States of America, joined Apr 2001, 226 posts, RR: 0
Reply 1, posted (13 years 5 months 1 week 5 days ago) and read 3111 times:

Sounds like a wonderful opportunity- I'm a bit of a V/STOL freak and as you would expect, high lift wings are one of the more popular technologies discussed- I'm not an engineer, so the sites that interest me are probably way to basic for you, but maybe they will give you some leads:

1. Overall STOL primer with rudimentary high lift wing theory-

2. V/STOL history- A great hodgepodge of VSTOL- Check out the wheel!

Good luck and keep us posted on your progress.

User currently offlinePeterba69 From United States of America, joined Mar 2002, 70 posts, RR: 0
Reply 2, posted (13 years 5 months 1 week 4 days 22 hours ago) and read 3094 times:

On the site for the Pima Air Museum, you can see some pics of Boeing's and M-D's approach to designing blown-wing designs of the 70's:http://www.pimaair.org/index.html. Boeing may be able to lead you in the right direction as well.

User currently offlineMartinKoschel From Germany, joined Jun 2002, 14 posts, RR: 0
Reply 3, posted (13 years 5 months 1 week 4 days 11 hours ago) and read 3088 times:

Thanks for posting me the links. I bookmarked them. Nice material to check out (80 meters for starting is somewhat cool....)

My main problem is though, that I need to come up with a standard/guideline one can use if e.g. a decision has to be made concerning which drive system architecture to choose for High-Lift System actuation on a commercial airliner.
Or what type of actuators to choose.

Material on trade-off procedurey / Methodology is hard to find and I am gld for every hint.


User currently offlineDelta-flyer From United States of America, joined Jul 2001, 2676 posts, RR: 6
Reply 4, posted (13 years 5 months 1 week 3 days 20 hours ago) and read 3072 times:


Trade study basics......In a trade study, you assess each alternative solution against the following typical factors.....
...performance (power consumption, efficiency, response,etc,)
...cost (both acquisition and maintenance -- i.e. - life cycle cost)
...Reliability, safety

The results of the trade study can be presented in a matrix. For each factor, assign a grade .... maybe 1 to 5, 5 being the best. When you add everything up, the highest number wins. Each factor's grade must be justified, preferably by quantitative analysis, in the form of a report.

If some factors are more important than others, you can grade them double or triple. The report must state all the assumptions used to arrive at the optimum solution (e.g. - the impact of cost is double the other factors because the market is very competitive and sensitive to price, etc.)

Good luck


User currently offlineMartinKoschel From Germany, joined Jun 2002, 14 posts, RR: 0
Reply 5, posted (13 years 5 months 1 week 3 days 15 hours ago) and read 3068 times:


thanks a lot for your posting. I am already that far, and roughly I know what a trade-off study is. And I have no problems when using criteria as weight, costs, reliability etc. My difficulty is to assess unscalable criteria in an objective way, e.g. functionality. Of course, you could just shoot for something like "ok, I'm gonna give it 3 points", but I am looking for a way that is more guided to kick out personal preferences as far as possible.
Plus, let's say you compare something that has been newly invented (and has some more bells and whistles) with something that is more 'old school' type of thing and does not have the new technology bells and whistles. On the old school beast, there weren't even requirements for the new features, and on the new project they are there because they are *required*. So how would you address this change in requirements in a fair manner? I mean you can't blame anybody for not having features that nobody required........the baseline is just a different one.......


User currently offlineBsergonomics From United Kingdom, joined Jan 2002, 462 posts, RR: 0
Reply 6, posted (13 years 5 months 1 week 3 days 12 hours ago) and read 3062 times:

Do you have any indication of the customer requirements? This is one of the major factors that we consider. For example, if the a/c is to be operated in remote, difficult areas (remember those photos of the airfields in Nepal?), then the overriding philosophy is: KEEP IT SIMPLE. This is a bit of a generalisation, but it means, for example, that reliability is FAR more important (in the grand scheme of things) than for an a/c that is designed to be operated primarily in relatively benign environments.

The definition of a 'Pessimist': an Optimist with experience...
User currently offlineDelta-flyer From United States of America, joined Jul 2001, 2676 posts, RR: 6
Reply 7, posted (13 years 5 months 1 week 2 days 18 hours ago) and read 3051 times:

Hi, Martin,

Bsergonomics mentions customer requirements -- of course that's a good starting point. Even if you do not have any specific customers, you can determine customer requirements through market research.

As for functionality, list each benefit separately and grade them. Be sure to also add risk as a factor (I forgot it earlier) -- that will offset some of the functionality.


User currently offlineMartinKoschel From Germany, joined Jun 2002, 14 posts, RR: 0
Reply 8, posted (13 years 5 months 1 week 1 day 3 hours ago) and read 3034 times:

Hi Pete and Bsergonomics,

thanks alot for replying. Shame on me i didn't post back the last days.
AS for now, I got aware of some very specific literature, that could be useful to me by recommendation of a student fellow who coincidentally fell over it while doing some other research. I think I'm gonna review that and I'll come back with some more specific questions in case else fails.

I am just in the middle of a trade-off study, and I did criteria ranking, weighting, scoring, ........ right now it seems to work fine.

Sorry not to provide more details, but I do not want to violate any company policies so I hafta stick to general statements...... :-|. That's why I asked for some kind of general literature in the beginning of the thread to beware myself of blowing out information by asking specific questions. Thanks for understanding.

Again, folks, thanks for your input.


User currently offlineDelta-flyer From United States of America, joined Jul 2001, 2676 posts, RR: 6
Reply 9, posted (13 years 5 months 1 week 1 day ago) and read 3026 times:

Martin, if you need additional ideas on handling risk, I have some information that will be useful for you.


User currently offlineMartinKoschel From Germany, joined Jun 2002, 14 posts, RR: 0
Reply 10, posted (13 years 5 months 6 days 4 hours ago) and read 3013 times:

Hi Pete,

would be fine getting some input on risk assessment

 Smile/happy/getting dizzy


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