Reverse Dehiderall Lifting Surface

[namdac]

I read that a company is starting to develop an aircraft that will only acheive a minimal height on a cushion of air under the wing. Please forgive my spelling error. I do however, would like any additional information available on the subject matter.
Thanks

 

[radomir]

Have a peek at thread1-33828, it may give you some directions. The most famous vehicle-aircraft specially designed for low-level flight is “Caspian Monster”.

Regarding "reverse dihedral" (wings clinging, hanging, something like this ^ ) it shouldn’t have much to do with that low level flight or so called (wing in) ground effect flight.

It is usually used to improve manoeuvrability of aircraft having ”top” wing configuration (too stable), mostly large transport aircrafts. The only “fighter” aircraft like that is V/STOL Harrier or AV-8A (Navy version) where top position of the wing was dictated by those V(ertical) T(ake)-O(ff) and L(anding) features (turning nozzles).

In case of those low-level “flying objects” wing must be at a fuselage “bottom”, closest to the ground (close to some water surface is much better, less scary), which is less stable configuration on its own. Reverse dihedral increasing manoeuvrability in that situation could be interpreted as increased instability, which sounds more dangerous. On the other hand it may be beneficial in order to efficiently avoid hills while driving the low-level flying object at a minimum speed of 200 mph. Just joking, or maybe not (about the minimum speed) but definitely that thing needs a lot of space to make a turn.

It just crossed my mind that there could be an advantage if negative dihedral produces a little bit larger lift for the same wing area (vaguely remembering something from a distant past).

 

[matt00000]

Reverse dihedral... Isn't that anhedral?

 

[radomir]

Sir Matt (assumption is that you are a male) I like your sense of humour.

In my previous post I also made an assumption that term “reverse dihedral” equals “negative dihedral” (the term I've heeard of) and I treated it like the negative. Hopefully the assumption was right, the correct one.

Sir Namdac (again an assumption that a homo sapiens named Namdac is a member of male population of those species) was very polite apologizing for possible spelling error. Therefore I took a liberty of interpreting “reverse” as “negative” (even three letters are identical, aren’t they).

Regarding my gender I used to be a male once upon a time but nowadays I am more and more inclining to a neutral.

Cheers Rad

 

[matt00000]

No, i am sorry i am neither male or female. I am just a rug used to clean the soles of shoes (or boots, its all the same to me!) and as such i have no sexuality... oh well

 

[namdac]

Radomir,
Gender has nothing to do with the question.(even though in my house it means everything)
I would like to find some type of information on the subject. I read an article in Pop. Mech. 10+ yrs. ago on the subject and found it quit interesting. There was a part of the article that talked about a finnish man who used this technology in the winter in finland about 1930's or so.
Regards,
Namdac

 

[matt00000]

If you look on the site more closely you will see another thread about ground affect a/c
thread1-33828 suggest if you are that interested you have a look there.

 

[butelja]

I believe you may be referring to the Boeing Pelican, which if built, will be the largest aircraft (WIG or not) in the world. You can find out more about it at:

http://www.boeing.com/news/frontiers/archive/2002/september/i_pw.html

.

 

[butelja]

By the way, I forgot to mention earlier...the picture in the link above shows that the wings have a definite anhedral. I'm no aerodynamicist, but I would surmise that the anhedral allows WIG at a lower altitude by minimizing wingtip vortices.

 

[matt00000]

Well read butelja!
The picture in the the link is of an artist's impression. A WIG of this size would need to use roll in order to turn. I wouldn't fancy being the pilot, regardless of how efficient the wing may be!
All the pictures I have seen of 'real' WIG's all have no anhedral or dihedral. To reduce the tip drag they all have fences or floats.
Anhedral is usually used to make an a/c roll faster but in this case it is to reduce tip drag. Experimental ideals do not always equate to sensible ideas.
Have a look at this link

http://www.se-technology.com/wig/

it has loads of pictures of actual WIG's nearly all of which have no anhedral or dihedral.