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Has Anyone Tried Ice Blasting?  
User currently offlineLehpron From , joined Dec 1969, posts, RR:
Posted (12 years 1 month 2 weeks 1 day 8 hours ago) and read 1174 times:

I made this up only a few days ago, I wonder if it has been tried.

You know how designers come up with a base idea and then blast it in a wind tunnel to redesign it over and over again to come up with the right shape? If instead, why not make a large frozen ice model and blast it in a tunnel? Yes it would melt, but that would reveal the natural shape.

If you held a cube of ice in the wind the corners would smooth off and the overall square nature would slowly "evolve" into a semi-sphere -- which is the more natural shape. (well actually a water droplet is the most natual shape but you get the idea)

If water is poured into a large model cast, then the portion of the wind tunnel acts as a refrigerator, freezing it to a solid; then the tunnel is automatically started to it's test speed when the cast is removed. As the model melts, lasers and radar are used to track or scan the change in shape and store the 3-D data, the contours of air carve out a slender vehicle before desintegrating. At the same time, a device for measuring the lift/drag coefficients record data from the changing shape.

The idea behind this is to gather data from differently shaped models without going back and forth on a design, I figure it would save money except for having to make several ice models. One can analyze via computer all the shapes the Ice Blast test produced as well as their Coeff of lift and drag and what not. Doing so might reveal a natural laminar-flow design.

The only disadvantage I can think of right now is by changing the AoA, the effective shape of the plane changes with accordance to airflow. Chances are, it will not look the same. But if the model is always pointed towards the wind, it should produce the same rate of change with respect to time.

How does this sound to you guys?

Comments/Questions?



15 replies: All unread, jump to last
 
User currently offlinePPGMD From , joined Dec 1969, posts, RR:
Reply 1, posted (12 years 1 month 2 weeks 1 day 7 hours ago) and read 1057 times:

The problem with a flow model like that is that when it comes to lift, it just won't lift because it is prefectly aerodynamic. They had a similar problem when designed the F-117, the computer gave them a shape that is perfectly invisible to radar, the only problem was that it couldn't fly.

User currently offlineMr Spaceman From , joined Dec 1969, posts, RR:
Reply 2, posted (12 years 1 month 2 weeks 1 day 7 hours ago) and read 1049 times:

Hi guys.

Good questions Lephpron. I don't know the answers to them, however, regarding PPGMD's suggestion that a perfectly aerodynamic aircraft couldn't fly...I can't help but think of the Bell X-1. It was basically shaped like a bullet (with a horizontal stab) and it certainly flew. Just an observation.


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Chris  Smile


User currently offlineFredT From , joined Dec 1969, posts, RR:
Reply 3, posted (12 years 1 month 2 weeks 1 day 7 hours ago) and read 1048 times:

Lephron,
try to find pictures of the styrofoam shapes attached to wing when certifying aircraft to fly in icing conditions. They represent heavy ice buildup on the wing and they are anything but streamlined!

Ice behaves in strange manners on wings. For starters, you'll have the highest temperature at the stagnation point and the lowest in the region of maximum lift on top of the wing...

Spaceman,
you might have observed those flat things sticking out of the sides of the X-1. They're called wings and they are what makes the thing fly...

Cheers,
Fred


User currently offlineMr Spaceman From , joined Dec 1969, posts, RR:
Reply 4, posted (12 years 1 month 2 weeks 1 day 6 hours ago) and read 1035 times:

Hi guys.

>>>FredT<<< HA HA HA HA HA HA HA Ha Ha that was Sooooo Funny!!!!!

Thanks for the rude comment aimed towards me. What's caused your attitude problem? Did someone piss in your beer?

Well, if you're supposed to be an "aero engineer", then why didn't you realize that Lehpron was NOT asking about the affects of icing on an aircraft. He was sugesting that if you allowed a rough form of an aircraft design made of solid ice to be blasted by air in a wind tunnel, adventually the airflow would natually form the most aerodynamic shape for that particular design, thus saving time and money on flight tests that are trying to reduce drag.

Of course you didn't pick up on his question because you were to busy trying to be a smartass with me! Why don't you try the Non-Aviation Forum when you have a bug up your ass.

By the way, I've had the pleasure of staring at the Bell X-1 with amazment in person at the National Air and Space Museum in Washington D.C. more than once, and you know what....I didn't know those things were called wings & made her fly. Thanks for the info, Mister.

>>>Lehpron<<< I think your idea is very interesting, but like I said, I don't know if it's been tried. Take Care.

Chris  Smile





User currently offlineJsuen From , joined Dec 1969, posts, RR:
Reply 5, posted (12 years 1 month 2 weeks 1 day 5 hours ago) and read 1029 times:

FredT's point is that ice does not have ideal behavior on wings! Airflow, temperature, and the surface of the ice interact in very difficult to predict ways. While the processes behind melting are somewhat simpler than freezing, the problems still remain. If you read his second sentence, you would have realized that.

They didn't design the wings like a bullet, did they?


User currently offlineJsuen From , joined Dec 1969, posts, RR:
Reply 6, posted (12 years 1 month 2 weeks 1 day 5 hours ago) and read 1018 times:

Also, may I point out that a perfectly aerodynamic design would probably be the most impractical in terms of cabin space and payload. Look at the center wing box area: it obviously could be made more streamlined, but it isn't due to structural reasons. Same thing with the flap track fairings. Those should be eliminated... but you need them for the flaps.

I don't think ice is needed for this. You can easily get the same data from a computer.


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User currently offlineMr Spaceman From , joined Dec 1969, posts, RR:
Reply 7, posted (12 years 1 month 2 weeks 1 day 5 hours ago) and read 1019 times:

Hi guys.

>>>Jsuen<<< Lehpron was not talking about ice on an aircraft's wing. He was talking about the "whole wing" , fuselage, tail, etc, being made out of solid ice as a model in a wind tunnel.

I mentioned the X-1 because PPGMD said that an aircraft with a "perfect aerodynamic design" wouldn't fly. The reason why I mentioned a bullet is because you can't get much more aerodynamic than a bullet. Can you???

I'm pretty sure that PPGMD and Lephron are very aware that any conversation we have in this forum about aircraft involves a flying machine that has wings! Or in some cases rotor blades.

FredT's response had nothing to do with the posted question. Then he decided to insult me. That's not cool, and what goes around comes around.

Hopefully someone will answer Lehprons question.

Chris  Smile


User currently offlineJsuen From , joined Dec 1969, posts, RR:
Reply 8, posted (12 years 1 month 2 weeks 1 day 5 hours ago) and read 1006 times:

My point and FredT's point are valid on all parts of the aircraft. Ice, actually phase changes in general, are dependent on many other factors. To put it bluntly, we are saying that due to properties of ice, its a bad idea. Making a perfectly aerodynamic plane is also a bad idea.

Before computers, colored oils were used, which eliminates many of the problems with ice. You can look at the density of the oil spray on the model.

Wind tunnel tests are increasingly rare today. With today's computers, there is little reason to use wind tunnels with ice or oil. They can do the same simulations more accurately, cheaper, and faster than wind tunnels.


User currently offlinePPGMD From , joined Dec 1969, posts, RR:
Reply 9, posted (12 years 1 month 2 weeks 1 day 5 hours ago) and read 1006 times:

The X-1 is not prefectly aerodynamic, it has wings, those wouldn't form with the ice model. These days computers are really good at the basic simulation, and thus are used more because you can change a minor thing and test it in a matter of hours instead of weeks and days that would happen in a wind tunnel.

User currently offlineMr Spaceman From , joined Dec 1969, posts, RR:
Reply 10, posted (12 years 1 month 2 weeks 1 day 4 hours ago) and read 1000 times:

Hi guys.

>Jsuen. That's good info about some of the wind tunnel techniques which were used in the past, etc. That's something we can learn from. However, I don't know why you're trying to defend FredT's reply so much. He started off his response by talking about styrofoam shapes that are attached to a wing when an aircraft is being certified for flight into known icing. That has nothing to do with Lehprons question about an idea he had.

I read Lehpron's origional post several times and I'm positive he wasn't expecting to hear about styrofoam, or any of this other crap for that matter.

Take Care guys.

Chris  Smile


User currently offlineWingscrubber From , joined Dec 1969, posts, RR:
Reply 11, posted (12 years 1 month 2 weeks 1 day 4 hours ago) and read 997 times:

Stop arguing guys. We're here to share opinions, not to bitch at each other.

I for one think it's a damn good idea. The advantages of this ice model idea are that you wouldn't have to make running modifications to a design you're trying to streamline. The complications of this are that you would need the facilities to make the ice, to shape it and to analyse it, and you wouldn't be able to experiment with aerofoils etc. where air pressure isn't even. (Uneven pressure would mean uneven melting of the ice) You could probably overcome some of these problems by combining the ice model with a metal carcass that wouldn't melt, i.e. metal wings, ice fuselage for instance.
One guy mentioned something about this being easier to do on a computer, probably quite true, todays software could easily eclipse this idea, which is a shame, considering it's originality.
Just for the record, as far as I know the teardrop is the most aero dynamic shape known to man, not the bullet, the bullet has a flat end; as a bullet or any other object with a flat rear passes through air, vortices of air are sucked along behind the flat face, which causes drag, no good. The teardrop has a pointed tail, which eliminates that drag.

Pete


User currently offlineJsuen From , joined Dec 1969, posts, RR:
Reply 12, posted (12 years 1 month 2 weeks 1 day 3 hours ago) and read 990 times:

Spaceman, to me FredT's reply is perfectly good. He says that ice has bad properties. Example: icing. Ice tests aren't done, the closet thing is icing test. My question is why you're construing his example as his point.

User currently offlineFredT From , joined Dec 1969, posts, RR:
Reply 13, posted (12 years 1 month 2 weeks 19 hours ago) and read 959 times:

Spaceman,
you made quite a glaring obmission when you stated that (paraphrasing) "perfect aerodynamic designs will fly, as the X-1 is a perfect aerodynamic design (with a stabiliser) and does fly".

I pointed out this obmission. If this dented your ego, may I suggest that you put a bit more thought into your posts in the future?

Trust me, if I wanted to be rude you'd know it. This is not the time nor the place however so lets end it here. If you want to continue down that road, do it by e-mail, OK?

Since you seem to have missed my point while talking about the no doubt fascinating, yet totally irrelevant, subject of beer additives, I'll try to clarify.

Those styrofoam shapes are representative of the shape of ice which forms on the leading edge of wings in icing conditions and thus also indicative of the shape the ice would assume in the proposed wind tunnel test. They are anything but aerodynamical, they look like the back of a camel in profile.

If someone can be so kind and point me to one of those web sites where you can upload an image for temporary linking, I'll try to draw one or even throw one in the scanner.

Another interesting anecdote is why de-icing boots are preferrable to heating the leading edges in flight. De-icing boots will let the ice form where the water hits the wing (the leading edge) and then break it up. If you heated the LE instead, you'd end up with runback (possibly a very local term for this phenomenon). The water flows back along the wing instead, freezing in the low pressure points on top of the wing. That's Bad with a capitol 'B'.

Cheers,
Fred


User currently offlineMr Spaceman From , joined Dec 1969, posts, RR:
Reply 14, posted (12 years 1 month 2 weeks 9 hours ago) and read 945 times:

Hello Wingscrubber.

I agree with you. The teardrop must be the most aerodynamic shape known to man. I mentioned a bullet because I read a book called "Yeager" decades ago and I think Chuck describes in this book that a bullet was the basic design for the X-1 that the engineers were going for...to help break the sound barrier.

Perhaps PPGMD is correct --- a perfectly shaped aircraft couldn't fly.

Regarding the arguing between myself, FredT and Jsuen...it has stopped!  Big thumbs up They didn't want to hear about my points of view and I didn't want to hear about theirs. Sh*t Happens.

BTW, I think your reply to Lehpron was great. I'm sure it's the kind of response he was looking forward to.

Chris  Smile


User currently offlineLehpron From , joined Dec 1969, posts, RR:
Reply 15, posted (12 years 1 month 2 weeks 9 hours ago) and read 942 times:

Wow, very interesting responses guys, thank to everyone! Big grins

I agree that computer simulations can pretty much blast the idea of Ice Blasting, but I feel in a small way it could be useful maybe for people who cannot afford all the simulation software, but then they would need some sort of 3-D scanning software to properly accept data from a melting aircraft.

Wingscrubber: The idea of using a sustained portion of the plane, i.e. metal wings or fuselage with the remaining to be of ice is a wonderful idea. Except that the metal might melt the ice and give inaccuate data, you what happens to cold turkey or steak when placed in a room temperature metal pan, right? Perhaps plastic or fiberglass or even styrofoam.  Smile

FredT: If ice on a wing is so dangerous as it alters sufficient airflow, then could a melting ice model reveal an alternate path for the flow that could be more acceptable? You've seen the dimples on a golf ball, for decreasing the drag and increasing the range? If aircraft wings had that it might give ice a place to build up without altering the overal lift performace -- I do worry about turbulence in this case. Also I think it was you that e-mailed me a few weeks ago, sorry I didn't respond yet, I will with a few days, I've been busy.

Mr Spaceman: I don't know about "a perfectly shaped aircraft couldn't fly", I think the end result of the test, as the limit of time approaches some value, then a standard lift wing would be carved into a symetrical non-lifter, but until then it might provide some lift. After some trials, it may be possible to use a perfect fuselage with an almost perfect wing, which wouldn't exist naturally, but its performance could be great.

Keep the "conversation" going you guys.  Big thumbs up


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