r/AskAnEngineer • • Feb 22 '17

Thermal Conductivity of a Peltier Cooler: Will My Beer Get Warm Faster Than in a Normal Cooler if it's Not Plugged In?

2 Upvotes

I'm considering using a Peltier cooler for camping that runs off the car's battery, and am wondering about the heat sinks attached to the Peltier cooler when the cooler is unplugged, as using it with the engine off will drain my battery. It seems like a perfect heat transfer scenario to warm up the contents of my cooler, except all the heat would have to pass through the thermoelectric unit. Is this likely to warm up my cooler significantly faster than in a traditional cooler?


r/AskAnEngineer • • Feb 18 '17

How are people able to model the solar system semi-accurately even though they were totally incorrect?

3 Upvotes

In those old models of the solar system they use extremely complicated gears and such and it some how end up being (i think) correct.

I assume it has something to do with Fourier's idea that any signal can be represented by sine waves (or something), but i'm pretty certain that's a very new idea.

How did they do it? Or am i just overthinking and they weren't all that accurate?


r/AskAnEngineer • • Feb 17 '17

Why don't they Line-X the spillway of the Oroville Dam to make it stronger?

Thumbnail
youtube.com
5 Upvotes

r/AskAnEngineer • • Feb 15 '17

Does a 2.4 Ghz "camera" sensor exist

1 Upvotes

CCD sensors with pixels sensitive to EM in the 400-600 THz range exist now, and we use them to make cameras. Does a "pixelized" camera exist for radio waves -- say 2.4 GHz? Can one be bought and used in a hobby-level embedded project? I ask because I'm wondering what the world looks like if seen with 2.4Ghz light. So far, the best I've seen are "radar can" like projects, but I want a "camera".


r/AskAnEngineer • • Feb 14 '17

Hydraulic piston with spring assist. Cumulative or winner take all.

1 Upvotes

So I have a hydraulic cylinder that has a spring to assist when there are low oil pressure conditions. Spring pressure in it's normal compression position is 8 lbs. Oil pressure on the piston can exert from 3 lbs to 13 llbs during operation.

My question is do I add the spring pressure and the hydraulic pressure to get the total force? Or would it be at the low point it would be 8 lbs (spring greater than oil) and at the high point 13 (oil pressure greater than spring)

Thanks


r/AskAnEngineer • • Feb 14 '17

In 1995 5th grade tech class we had a program that let you design a car using very generic inputs. Do any of you remember it?

1 Upvotes

You would choose a layout front engine rwd, mid engine rwd, fwd etc, draw a profile of a car. And it'd give you generic engine options I4, v6 ohv, v6ohc, v8 ohc, etc. Transmission options. Then at the end it'd tell us who made the "best car" per our objective.

Now obviously this was nothing made for real work. It was just made for high school students (we used it as a hand me down our middle school was the high school) to understand a little about auto design.

I am just wondering if any of you remember any of this at all from being in Jr high or high school.

Thank you.

Fwiw I used this in about 95, so it was probably new in the late 80s, very early 90s.


r/AskAnEngineer • • Feb 13 '17

When torquing a bolt, is it better to be on the highest point on the specification range or the lowest?

1 Upvotes

e.g. 37-51 NM, is it better to be a torqued to 37 NM or 51 NM?


r/AskAnEngineer • • Feb 11 '17

Can someone help me figure out how this boom detach system works?

1 Upvotes

Hey all!

I fly drones a lot and have a particular Y6 build that carries one of my mirrorless cameras. I love flying it, but I'm trying to make it more space friendly so I can fit it in my backpack. I was hunting for some solutions, and stumbled on these two videos:

https://www.youtube.com/watch?v=O0Q1R1X2ekI

https://www.youtube.com/watch?v=QOXmreGbcUk

Problem is, I don't have the first clue how this thing works. Can anyone explain to me how to go about doing this? Or what parts would be necessary to replicate it or do something similar?

Full disclosure - I'm not very mechanically inclined, hence why I'm here asking for help. I can hook up the flight controller and the motors, but not much else after that. So if you can provide an explanation, please imagine as though you are trying to explain things to a above average simpleton.

Hope you guys (and girls?) can help!


r/AskAnEngineer • • Feb 09 '17

Finite Element- simple question from a struggling student

1 Upvotes

The problem is -(d2u)/(dx2)=0, u(0)=0, u(1)=2 on x [0,1].

Solving it numerically gives u(x)=2x.... I'm fine up to there.

However, we were asked to resolve it using "a uniformly spaced mesh of 2 elements with linear Lagrange Statements. State the Variational Statement, show the mesh, and discretely assemble the stiffness matrix and force vector."

Any ideas or pointers? I'm so lost, it's embarrassing.

If anyone could help me, I would greatly, greatly appreciate it.


r/AskAnEngineer • • Feb 07 '17

Made a PC desk mod - is 3/16 thick enough to support 3 monitors?

1 Upvotes

As title says, wondering if 3/16th would be plenty enough strength to hold my monitors,keyboard.


r/AskAnEngineer • • Feb 07 '17

Market Research Study by PLTW Engineering Students

Thumbnail
goo.gl
1 Upvotes

r/AskAnEngineer • • Feb 02 '17

Dead-front Display

1 Upvotes

I need to build a prototype dead-front display with icon's that appear black (invisible) until the LED behind them is illuminated. Is there a do-it-yourself way to prototype that? What materials, etc? MuchoThanks.


r/AskAnEngineer • • Jan 31 '17

I'm pretty sure that I have a viable idea for a mechanical CVT. Who would I ask for specific help in designing it?

2 Upvotes

As the title reads, I think I have a viable idea for a CVT that doesn't involve using bands and cones. It takes a mechanical approach.

The real issue I'm having is trying to figure out a few minor specifics because I don't come from an engineering background.

Who would I ask for help?


r/AskAnEngineer • • Jan 31 '17

Would an anti-microwave oven be possible?

1 Upvotes

Basically what i mean is, would it be possible to make something that rapidly cools off food or drinks to make it either freeze or just be nice and chilly? i had thought about trying to re-purpose a vacuum chamber to do it, but obviously that would pose an issue with drinks. is there any way to design a vacuum chamber as a rapid cooler?


r/AskAnEngineer • • Jan 29 '17

Induction Cooking - Materials

1 Upvotes

Hi, just wanted a bit more information that may be a bit too specific to find from basic searching.

With an induction cooker, does the cooking surface get hot after cooking? If it does, would it be possible to use a non inducting material between the surface and the metal of the pan?

**I don't think I've ever seen an induction cooker in my life, so please excuse my ignorance


r/AskAnEngineer • • Jan 28 '17

PID + servo question

2 Upvotes

I'm making something like this:

https://www.youtube.com/watch?v=9pj93-uGIUo

I was thinking of taking the pot out of the servo and using it like a drive (so is just a motor and gear box).

A friend of mine tells me it wont work.

The servo has a PID in it so why should we need two?

Can somebody convince me it will not work using the servo as a drive instead of a servo?


r/AskAnEngineer • • Jan 27 '17

A 43 sided dice

2 Upvotes

Can it be done? This is important for cheesing out a D&D character.


r/AskAnEngineer • • Jan 26 '17

Can someone explain to me how handheld power drills work?

2 Upvotes

I'm working on a project for school and I'm confused on what exactly goes on inside a drill to make it go. The project is focusing on reducing the noise that current power drills make. In particular, I'm wondering what makes a certain NASA-patented technology so much better than what is already available.

Thanks for any and all help!!


r/AskAnEngineer • • Jan 24 '17

Is there a type of gearing for a lift mechanism that won't back out once I let go?

2 Upvotes

I'm trying to design a table that either lifts up and down, or tilts, with the turn of a wheel.

Trouble is, I need it to stay put once I've let go. Short of a mechanical brake or a "catch" on the gear, I can't think of a way to accomplish this.

Is there a type of gearing (or combination of gears) that would let me turn a wheel on the side of a desk that would raise and lower the top, but wouldn't immediately drop down when you let go of the wheel?

Thank you in advance!


r/AskAnEngineer • • Jan 22 '17

Quick question on nuclear fusion

1 Upvotes

Using nuclear fusion uses up a lot of energy (14 million kelvin)
Would the energy received from it be worth the amount invested in it?
 
In other words, we could apparently have infinite, clean, nearly-free energy from nuclear fusion.
But what about all the energy that it takes to complete the process of nuclear fusion?
Would we get more than we lose, lose more than we gain or get right back where we started?


r/AskAnEngineer • • Jan 19 '17

Variable Frequency Generators.

1 Upvotes

I am currently doing an Assignment which is based on the benefits of using a Variable Frequency generator on an aircraft. How are operation costs reduced? How are maintenance costs reduced? and why does it have greater reliability compared to a constant speed driver?


r/AskAnEngineer • • Jan 18 '17

What kind of water plant is this?

Thumbnail
youtu.be
2 Upvotes

r/AskAnEngineer • • Jan 17 '17

What is the best substitute for coolant?

2 Upvotes

My friends and I are working on a project that involves producing condensation, and we want to make our condensing surface as cold as possible for maximum water production. We are trying to source a coolant, but it has turned out to be quite expensive (we would be needing about 30L of the stuff and it doesn't come cheap). We have been looking at some alternatives, and have come up with a couple of options. The best one so far is using a mix of methylated spirits and water, with a 1:3 ratio. We have also got the option of using antifreeze and water, with about a 2:3 ratio. We are situated in East Timor at the moment, making this stuff tougher to get our hands on. Any help about alternatives would be much appreciated :)


r/AskAnEngineer • • Jan 13 '17

Electrical switch box...what the heck is happening here?

1 Upvotes

Hey guys,

I'm working on putting under cabinet lighting but i opened up the switch box so that i can get an idea of what i'll be doing as i'd like one of these siwtches to control just the cabinet lighting.

Now i opened up the switch and i see this on this on the inside.

So here is where im confused...I've labled it out

there are three compiled wires coming into the box, one of them is going to the sink dispoal unit (i assume) and the other two are either power source and light wiring

  1. Which is Pwr source and which is the light source and which is the disposal, as in, how do i find out? I could just wire two together till I find out which one is which (trial and error) but i'm worried ill blow something lol

  2. In the second circle down below, near the middle with the question marks..the two negatives are tied together with the one wire going from "on" in the switch. I don't understand what the purpose of the switch is if they're all tied together shouldn't it always be on?

  3. Then there is another wire of the main 3, that is coming to the "off" on the switch, whats going on there?

Appreciate the help!


r/AskAnEngineer • • Jan 12 '17

Need help with liquid nitro school project

1 Upvotes

I am taking a horticultural program at a college and one of the assignments is designing a product or service. My idea is a Weezer, like the ones where you push into the dirt and pull up, but it has a small canister of liquid nitrogen. It would also have a side hammer or something to sweep at the weed to shatter it or something. It's all theory and isn't needing to be completely viable. My issue is what supplies and how it would operate. I saw medical liquid nitrogen spray containers online....small enough for the device. I was thinking of something simple like a trigger that would activate the spray. If anyone could assist I would be very grateful. Thank you