will it take off?

[Egon]

Hey I'm still posting!!

 

[patrick_g]

Lets see if we can do a philosophical merge of the two topics, Eddie's pond and the will it fly.

How about a sea plane in Eddie's pond and a large prop in the water to create a counter current to move the water backwards past the plane as fast as the plane moves forward with respect to the dirt. OR, have the prop move the water past the plane as fast as is required to make the plane stand still (to cover both versions of the problem statement.)

Pat

 

[tallyho8]

I think Eddies going to need a larfer pond.

 

[MossRoad]

Lets see if we can do a philosophical merge of the two topics, Eddie's pond and the will it fly.

How about a sea plane in Eddie's pond and a large prop in the water to create a counter current to move the water backwards past the plane as fast as the plane moves forward with respect to the dirt. OR, have the prop move the water past the plane as fast as is required to make the plane stand still (to cover both versions of the problem statement.)

Pat

Make sure it is a magic prop and I'm all for it!

 

[TomOfTarsus]

I think Eddies going to need a larfer pond.

I think at this rate TommyOf Tarsus is going to need some prescription migraine medications.

 

[patrick_g]

Make sure it is a magic prop and I'm all for it!

Moss, buddy, problem statement #2 which has the prop moving the water backwards past the plane as fast as is required to stop the plane's forward motion, is in fact a "Magic Prop" per se in that it is the analog to the conveyor with the same capacity.

It should be well within most reader's visualization capacity to see that finite and probably achievable water velocities generated by a large prop in the water powered by a large engine could in fact prevent a float plane from making any forward progress with respect to the frame of reference defined by the land. I assert that for many folks it is easier to visualize a variable speed "river" acting to push the float plane backwards enough to stop the plane's forward motion than it is to do the same with a rapidly accelerating conveyor stopping the plane through the reactioin of storing energy in the rotating wheels, friction of sliding tires, etc.

All that is required to hold the plane motionless (not just ****** its forward speed below take off speed) is for the speed of the water moving toward the plane to generate sufficient hydrodynamic drag in the float to equal the thrust of the prop. Even allowing for the fact that at some speed the float will "get up on the step" (begin to hydroplane and exhibit a considerable reduction in drag) and leave the speed regime where displacement hull speed restrictions are so great. This will require the immersed prop to really speed up to move the water fast enough to generate the requisite drag on the float while planing to keep the float plane standing still with respect to the pond's banks.

Since the plane will not be permitted to move forward due to the moving water, the size of the pond is not an issue since it is clearly large enough to easily contain a float plane. The potential down side for Eddie is the terrific current set up by the submerged prop will muddy us the pond but it will settle out a gain after the experiment is finished.

Eddie will get bragging rights and the snobability of installing a commemorative plaque and statue on shore next to the site of the experiment and undoubtedly a newspaper writeup and TV interviews.

Pat

 

[turnkey4099]

But when I have proven it won't take off and go to anchor, will the level in te pond go up or down when I toss out the anchor?

Harry K

 

[patrick_g]

But when I have proven it won't take off and go to anchor, will the level in te pond go up or down when I toss out the anchor?

Harry K

The pond level will go down when you deploy the anchor assuming:

1. You had the anchor on board during the trial.
2. The anchor is made of metal (or heavier than water material.)
3. The pond is not full and overflowing.

When on board the plane the anchor causes the plane to sink deeper into the water until a volume of water equal to the weight of the anchor is displaced making the pond rise a little.

When the anchor is tossed over the side and allowed to be supported by the bottom of the pond the water displaced is equal to the volume of the anchor, not its weight. Since the anchor is more dense than water (or it wouldn't sink) the displaced water when deployed is significantly less than when supported by the plane.

Pat

 

[Egon]

Forget the pond! Just head for a fast flowing river!

 

[Egon]

On second thought, forget the river, head to Jimmy Angel Falls and try and take off going up the falls!