Studing WIG (Wing In Ground Effect)

[kach22i]

Originally Posted by DFV

Nope, not mine, I stole it from:
http://www.gizmag.com/go/6864/
Glad you like it. Looks feasible to me.

Looks like it would rip the riders legs off as they are in the air-flow.

http://www.gizmag.com/go/6864/picture/31429/

[kach22i]

Originally Posted by skippervs

This is a skethch from Russia. Have a look at something new too.

ekranoplan KASATKA-5

I find it helps to provide a link to the image just in case it does not take, and to give proper credit.

Link to pictures:
http://airboat.fatal.ru/index_en.htm









Again, I think flying low in an area known to be filled with bandits, gunmen and pirates is inherently dangerous. But that's just my opinion.

There is a reason they put a fence around an airport.

[DFV]

Referring to comment #61
Nawwww! Don't think it was meant to go supersonic. Just a PWC with some captured air-flow to ride on. Still, looks dangerous, don't it? Lots of sharp edges to get caught between, on, and against.
What fun? Let's lose a limb.

[kach22i]

In my small hovercraft I experience birds and other wildlife crossing my path. Quite often they are confused and end up flying along side my craft trying to outrun it, and often exhausting themselves in the process. There is nothing I can do about this, I slow down as much as I can without coming off air cushion - what else can I do? I guess if you drive a car, you may hit an animal crossing or laying on the road, in a boat perhaps hitting another boat, a swimmer, and under the water fish or a crocodile. These are the risks we accept and take with any form of transportation.

http://www.birdstrike.org/events/signif.htm

The U.S. Department of Agriculture, through an interagency agreement with the Federal Aviation Administration, compiles a database of all reported bird/wildlife strikes to U.S. civil aircraft and to foreign carriers experiencing strikes in the USA. Over 38,000 strike reports from 1,300 airports have been compiled, 1990-2001 (about 5,900 strikes in 2000). The FAA estimates that this represents only about 20% of the strikes that have occurred. The following examples from the database are presented to show the serious impact that strikes by birds or other wildlife can have on aircraft. These examples demonstrate the widespread and diverse nature of the problem and are not intended to criticize individual airports. Many of the strike examples reported here occurred off airport property during descent, approach or climb

[skippervs]

The same is happenning to any car on the road, but one still can see many cars around.
This WIG fly well

[Geob]

First of all I would want to thank you for all the information that you have given here. Also I am very glad that exists and other individuals that deal with WIG's. Also I apology for my long interval from here.

I have advanced my project therefore I am in place mention to youbasic elements for WIG Crafts.

Now I post some requires for WIG Crafts :

the motion of a WIG before the take-off can be devided into two regimes. a) the transitional mode and b) the planing mode. In order descry these modes we use Froude Number. So :
a) Fr < 3
b) Fr > 3

In the second mode the hull an specially the planing surface treated as a wing. This phainomenon help the WIG to take-off. But the problem in this mode is the unknown wetted surface.

Also very important is the Static stability, and I choose first the static because is more scrutable.
a) If AC = CG then Xh = 0 In this case the Pitch Angle does not vary with speed.
b) If AC < CG < PC Then Xh > 0 & ΔΧ > 0 In this case the Pitch angle decreases with increasing speed
c) If CG > AC Then the damping effect of the ground effect is decreased

So the perfect position of CG is in Fig 1

I believe that these are very useful requieres. I want to discuss these and then I performance more things.


And now I want your help in this problems:
1) In this moment I want to build a model, but i have construction problems such as the material to use etc... (wood, plywood, balsa, fiberglass, epoxy etc)
2) In the mode before the take-off we calculate the Froude Number, but in the mode after the Take-off wich derivative or analogy I can use? In order to compare WIG's

This is a link of a RAM-Wing (not excactly WING) model that you can build easily with hard paper (i build this and is very good)

http://g5.damp.tottori-u.ac.jp/WISE/ramodel.html


Thank you one more time...

[skippervs]

Hi, Mr. GEOB, How are you?
I prefer plastic50-100kg\m3 and epoxy to build up scale models. It’s cheap and suitable.
The 1to10 scale WIG boat model I finish now is built in this way.
The aerodinamic tests for S.CoreaWIG boat wereconducted in Kiev hidrodinamic basin, Ukraine.
Hidrodinamic tests are much cheaper then aerodinamic tests and the owner saved a lot of money. So, it is possible to use Fr for flighing objects too. No difference to fly where- in the water or in the air. Air density x1000 ~ Water density.
What’s around stability in the air or on the water?
It is better to send letters to e-mail: andrewvasilakis@yahoo.co.uk
Sincerely,
AV

[Geob]

Hi Mr Skippervs and thanx for your reply.

I have the ability to make Hydrodynamics and Aerodynamics tests as I am a student in my University. But for my fisrt test i can't use a model in 1/10 scale, because I have problem with the air tunnel. If I have success to these tests, then i build a bigger.

Thanks about the Fr. But I have a question: Can I use Fr in Low and High Speed? The air density is the same in high speeds?

I am interested about air stability.

I will contact with you for more details.

Thank you very much.

[skippervs]

Hi, Mr GEOB.
You mean the scale effect, isn’t it?
Figuries are different for water and air. You have to use Fr when making boat tests in the water for low and high speed.
The air density might be different for scale and different for speed figuries. You have to check detailes in aerodinamics. What scale of model do you use for airtunnel?
How big airtunnel your university have?
Sincerely, AV

[RatliffFranklin]

Originally Posted by skippervs

Hi, Mr GEOB.
You mean the scale effect, isn’t it?
Figuries are different for water and air. You have to use Fr when making boat tests in the water for low and high speed.
The air density might be different for scale and different for speed figuries. You have to check detailes in aerodinamics. What scale of model do you use for airtunnel?
How big airtunnel your university have?
Sincerely, AV

Look up "Reynolds Number" and how it relates to wind tunnel testing.

[kach22i]

http://www.australianhovercraft.com/...aft_photos.htm


Worlds First Wing in Ground Effect Marine Craft fully surveyed to IMO Rules. Manufactured in Australia. Picture provided by new owners in Singapore.

[skippervs]

kach22i Hi. I tried the thead www.ausrtralianhovercraft.com and found it is not available.
My WIG scale model is still not ready for tests.

[kach22i]

Originally Posted by skippervs

kach22i Hi. I tried the thead www.ausrtralianhovercraft.com and found it is not available.
My WIG scale model is still not ready for tests.

I don't know anything about the company, just that I've had their website bookmarked for several years. The site is down right now, but copies of it are here:
http://www.jameshovercraft.co.uk/hov...ges/buying.htm

As far as not having a model yet, I wish you luck. I was told once that models can cost little, but take a lot of time. Add in the engineering and it lot's of time and money. This is one of the reasonns computer modeling is so popular.

You know the work of Lippisch and his WIG's, right?

Google image search:
http://images.google.com/images?svnu...=Search+Images


EDIT:
It's far from easy to do a WIG right, the Flarecraft looks great, but would you trust your life with it?

http://www.se-technology.com/wig/htm...code=&craft=49

The Flarecraft L-325 was the first commercially available WIG vehicle. It is a further development of the L-324 prototype. The main differences are that the L-324 carries one pilot and three passengers, while the L-325 can accomodate four passengers and the L325 has a more powerful engine, furthermore the L-325 is equipped with a small water jet for harbour manoeuvring (Yamaha 47kW).

There were plans to produce about 5 vehicles per month. Only a few L-325 have been sold, because problems arose with the crafts stability. Apparently Flarecraft didn't copy the Airfisch 3 accurately enough.

Apparently Flarecraft still continues to market the L-325, even though some serious problems have occured and craft even crashed. Aside from the stability problems it was reported that the vertical tail was not stiff enough, causing the whole tail to "wiggle" in flight, requiring rudder input. Furthermore the fuel tanks were not located near the cg, causing problems at an almost empty tank.

[skippervs]

kach 22i.
Many thanks for the reply and sorry for the delay.
Yes I know Lipish WIGs and my own is very close to his idea.
Models I have built are cheaper then comp model. It is not a problem to use comp but I prefer to use both ways to be more sure. All the talks and discussions around this WIG show it is the wight way and I hope to start real boat 3 seater and to build her this year

[smenkhare]

Originally Posted by kach22i

http://www.australianhovercraft.com/...aft_photos.htm


Worlds First Wing in Ground Effect Marine Craft fully surveyed to IMO Rules. Manufactured in Australia. Picture provided by new owners in Singapore.

Flightship is now bankrupt and the plans to the F88 dragon have been sold to some turkish company.