The Wright Bros' experiments were more accurate than those of previous experimenters, but still quite approximate. That is one reason that the rounded leading edge came a bit later.
Granted ... but an order of magnitude is huge!
So they tested baby wings with something like 30 mph wind. For the sake of discussion suppose 10x is the exact scale factor. Does the Reynolds equation say that full scale wings can fly at 3 mph?
Reynolds does not predict flight performance per se, but yes, you can lighten a human-powered aircraft enough to support its own weight and hang together at 3MPH. Models do it. Wings are often tested at 3,6 , and 9 million Re, and the data curves are quite similar. The forces scale strongly with speed, but the details just change enough to make it worth checking. It is mostly about how much the shape is getting padded out with sticky air.
Reynolds does not predict flight performance per se, but yes, you can lighten a human-powered aircraft enough to support its own weight and hang together at 3MPH. Models do it. Wings are often tested at 3,6 , and 9 million Re, and the data curves are quite similar. The forces scale strongly with speed, but the details just change enough to make it worth checking. It is mostly about how much the shape is getting padded out with sticky air.
Just wanted to say thanks, Bob. I searched a bit. I can find 110V fans for several hundred bux that push well over 10k cfm. I could test well below 60 mph. Scale models don't have to be 1/12-th or less. Combined, a practical sweet spot seems possible. This is a good project to keep inching forward.
Just wanted to say thanks, Bob. I searched a bit. I can find 110V fans for several hundred bux that push well over 10k cfm. I could test well below 60 mph. Scale models don't have to be 1/12-th or less. Combined, a practical sweet spot seems possible. This is a good project to keep inching forward.
Bob,you can also do a water tunnel as did Mythbusters for the F-150 tailgate episode.The water is 833X more dense than air and I'm pretty sure you get good Reynolds number 'verisimilitude' at relatively low flow velocities.
This was done at Texas Tech.Food coloring was injected into the flow field just as smoke in a wind tunnel for visualization.
To get a good Cd you need about 20 mph airflow at full-scale.A 24:1 scale model would require a 480 mph airstream.
I'm curious how much modification can one make to the frame and chassis of an automobile before it can no longer be recognized by the department of motor vehicls (DMV) and registered.
Wit the dolphin, I can still see the Geo Metro up front, but the rear has been chopped and reformed.
Can the original Geo be modified to something with even less drag - ie. a 2 seat tandem, 3 feet wide and torpedo shaped with moped wheels and dropping the total weight down to 800 pounds? Could you still register and have it inspected as a Geo and pass a safety inspection?
Or is there no limit except to retain the VIN number plate somewhere on the dash?
BiiHoo the requirements vary wildly from state to state so you have to check with the DMV where you intend to attempt such a feat.
Yeah, I think this is pretty much the answer. Depends on the state.
BTW, modification standards are obviously looser for motorcycles. You see some pretty wild mods mostly nationwide. And in most states, 3 wheelers are considered motorcycles. I point to the various 3 wheelers which are basically VW beetle on the back half and motorcycle suspension in front. This looseness apparently extends to 2 wheels in front, one in rear.
It seems to me that a serious modder might consider some type of 3 wheeler if the auto standards are too tight within his own state. Just thinking out loud.
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