Science Buddies: "Ask an Expert"

Hi. I'm doing this project. I'm starting to assemble the lego pieces. The directions say to scale down the original measurements to 1:5. This would make my bird 7 inches long x 12 inches wide! The extra large baseplate they said to order is only 15 x 15 inches! The pictures of this project doesn't make the birds look this big. Am I missing something or can I scale it down further to 1:10 or 1:24? Thanks for your time.

Trevor
5th grade

I think you need to check your centimeter to inch conversions (https://www.google.com/search?q=convert ... irefox-b-1)

The wingspan of 108 cm = 42.5 in and at a scale of 1:5 this comes out to 8.5 inches.

The distance from beak to tail is 66 cm = 26 in or 5.2 in at 1:5

The average wing width is 23 cm = 9.1 in or 1.8 in at 1:5

Try making bird models close to this size and see how they look on the base-plate. The Lego blocks are not going to give you exact measurements. The important thing is to have the shape similar to what is shown in the project procedure and to make sure the models are identical.

Let us know how they look using these dimensions.

Sybee

Thanks. I was hoping to do the experiment on the Canada goose which is a little larger than the pink footed goose. It's mean beak to tail is 36.6 inches and its mean wingspan is 58.45 inches. Scaled to 1:5 it's length would be 7.32 and wingspan 11.69 inches. Almost half my board. My mom and dad thought we could scale it to 1:8 which would be more like the pink footed goose. Would it mess up the experiment to do it at a 1:8 scale or should I just perform the experiment exactly the same and use the pink footed goose instead of the Canada goose? Thanks for your time.

Hi,
I don't see any reason why you can't use the measurements of the Canada goose. Just scale them down 1:8 instead of 1:5 so the model will fit on the board. Just make sure you do the math right and double check the measurements on your models.

Please post back and let us know how your experiments came out.

Sybee

Great! I sure will!
Trevor

HELP! When I turn on the fan for my experiment the reading are coming out negative. Is this right?! Is this supposed to be upwash?

I read the procedure again :

https://www.sciencebuddies.org/science- ... #procedure

and what it says is that the scale measures the drag on the fixed bird. If you have the lever attached in the correct place and positioned on the scale correctly then turning on the fan should result in a positive force from the air pressure. At first I was thinking that you might be getting lift from the wings, but I don't see how that is possible because the wings do not have the curvature needed to create a lower air pressure on top that makes lift.

I would try raising or lowering the fan or the platform to change the angle that the air hits the bird. Make sure that the blades of the fan are perpendicular to the surface. The directions say to place the fan 60 cm from the base plate. You could try changing that distance and see if it makes a difference in the force.

Check the upwash effect online and find out more about it. I don't know if it could occur with your models or only with a properly shaped wing.

If any of the other experts have experience building and testing this model, please let us know what you think.

Let us know what happened.

Sybee

Thank you! We figured out why we were having an upwash effect. Our scale had a lip on it and when we turned on the fan it was blowing that lip on the scale creating upwash. We put a ruler in front of our scale and that did the trick! Finished the experiment with positive results. Thanks for your help. I'm making sure to include this in my notes!!
Trevor

Great, Trevor! Good detective work figuring out the solution to the problem. Thanks for letting us know.

Sybee

Thanks! My dad actually was the one who figured it out. Took us 5 hours! We tried everything!

Well, great teamwork then!

Elon Musk's new, big Falcon Heavy rocket was not the product of a single person. Lots and lots of engineers, mathematicians, designers, materials scientists, chemists, physicists, etc. worked long hours to create this amazing vehicle. I'm sure there were a zillion little problems along the way like your 'up-wash' that they had to solve. Success is what matters and the satisfaction of knowing that you did a great job.

Looking forward to working with you again on your next sci project--make it an even better one!

Sybee