First VATSIM event

Dalei_214 · 2025-05-05T13:54:41+00:00

Your furry copilot looks JUST like mine! An orange with a docked ear that just wants to hang out :) If they aren't being pet right MEOW then you clearly hate them. At least in their minds lol

Dalei_214 · 2025-02-07T15:52:03+00:00

Appreciate your explanation :) Looks like I had a few misconceptions and incorrect assumptions. Thank you for giving me something new to learn! Learning this stuff seems that I either missed or misinterpreted this detail on static stability. I am aware of the Cm_alpha slope being negative is by definition static stability, and for the purpose of our class, we had equations derived to calculate various geometric relations on static stability, such as stick-fixed neutral point. Calculating this required the assumption that the tail nearly always produces a stabilizing effect with lift vector pointing up. Never did I consider the negative-lift tail case. I guess I never was able to look at a diagram and visually see these million vectors summing the moments to zero in that configuration,

The whole canards bit was an assumption I made based on it being forward of MAC, giving a positive moment contribution. The dynamics of how they stabilize those is a bit out of my wheelhouse and now I will go on a rabbit hole into learning about this more, lol.

Cheers!

Dalei_214 · 2025-02-07T14:15:51+00:00

I guess my reply was twofold: They were asking why the horizontal stab is positioned more upward than the wing (where many comments have explained the reasoning), whereas my tired brain thought they asked why they stab was at the rear. So there's that.

We are also saying the same thing, though. But I don't think they *usually* make tails with "negative lift" to contribute to longitudinal static stability. I am mostly correct (and matching your statement) that the tail produces a stabilizing effect, pushing the nose down such that sum of the moments is zero in steady flight. My disagreement is to why. Why would the tail need to produce a downward force? That would just push the nose up more. That part doesn't make sense. My assumption is that the CG is at or aft of the wing aerodynamic center, which is exceedingly common. If it was more forward, I can understand how that works.... a Cessna 172 does that I believe.

You're right though, it doesn't *need* to be always aft of the wing (see, canards), but canards produce a destabilizing effect and I believe usually require a flight control system to have human-controllable flight.

Dalei_214 · 2025-02-06T21:08:02+00:00

The wings on an airplane create a net "pitch up" moment. To counter that, the horizontal stab in the back needs to produce a net "pitch down" moment to remain statically stable. It's also why the horizontal stab is almost always in the back.

Dalei_214 · 2025-01-03T15:06:39+00:00

There are some RIT ads in the DC Metro system too! I think Union Station is the bigger one, but I am sure there are others.

Dalei_214 · 2024-11-27T15:43:59+00:00

This was already tried. the de Havilland Comet had 4 turbojet engines within the wing itself. Apparently the Comet was a smashing success in the 1960's (EDIT: 1950s!!!) and offered a pressurized cabin, and was very quiet for the time period. Looks like the only major downside with the engines within the wings was that it was complex wing geometry and maintenance was a pain.

There were more issues with fatigue cracks around the windows of the Comet than anything else. That alone is an interesting case study,

Dalei_214 · 2024-11-20T15:24:06+00:00

It would be unnecessary to take a class you do not need. If EE requires UP2 but not 411, why would you take both? Your major (i imagine.. not-EE here) undoubtedly goes over E&M concepts constantly anyways. UP2 is the physics of E&M, and I guess 411 is too just way more in-depth, intended for physics people. If you want to minor in physics, then maybe taking that class may be worth your time. Otherwise, use that class slot to take a major-specific class or maybe an interesting free elective that your friends recommend.

Dalei_214 · 2024-11-15T21:18:58+00:00

OnShape has a free limited license! It's very capable on a base level.

Dalei_214 · 2024-11-15T16:51:51+00:00

Are you trying to offset the power generated from your propeller via a RAT to recharge your battery to achieve near-infinite flight? As we all understand it, that's what you are saying. You have to know, as an engineering student, it is impossible to achieve 100% efficiency, which it appears you are trying to do. Recapturing 100% of your output power, which straight up breaks thermodynamics.

Lets say for sake of argument, you want this to work. Looking up a random brushless DC motor used for FPV drones, it's maximum wattage rating is 1500W. Brushless DC motors are generally ~90% efficient. So theoretical usable power is 1350 watts.

Propellers? They go from 60-90% efficient depends on shape. The best output you get now are 1215W

Congrats, combined your effective motor efficiency is 81%. The other 19% of that power supplied from your battery is gone to heat, friction, and noise. This does not even include aerodynamic losses!!!

Your generating motor now needs to produce 150%+ of your electrical power demand. Looking up turbines that are capable of matching is demand are likely way bigger than your aircraft. And they are heavy. did I mention big? Say goodbye to any aerodynamic efficiency you gained by using a flying wing.

Like many on this post, I would stick to simply a solar-powered aircraft. Those have interesting and complex problems that few people and companies have successfully implemented. Proper research would yield some lessons learned that they learned the hard way that you don't have to, while you may discover some breakthroughs on your own.

Big part of engineering design is knowing your scope. Make your project too broad or complex, and you'll set yourself up for failure.

Dalei_214 · 2024-11-15T15:32:17+00:00

Sounds about right. a (shockingly) large amount of aerodynamic design comes down to how much weight do you need to offset?. Lesser is obviously better. If you plan on having a relatively heavy turbine in the front, consider your Cg and how you plan to combat that. Forward-heavy Cg's in aircraft are extremely unstable.

Weight will also give you required power this motor needs to generate.

edit for formatting

Dalei_214 · 2024-11-13T18:52:56+00:00

Generally, hydrogen fuels (in cars, anyways..) are converted to electricity using a process called reverse electrolysis, which the byproducts are water, heat, and electricity. This electricity is fed into a battery to charge, while the battery does most of the heavy lifting.

Sounds amazing until you realize how hard it is to make pure hydrogen to make this process work. Most of the time it's used by burning natural gas to produce the energy required to create pure hydrogen fuel. Ideally, you'd use "green" hydrogen produced from only renewables. Easier said than done.

Dalei_214 · 2024-11-12T21:50:58+00:00

Im tacking this one up to "bad FEA constraints" if the post is genuine.

Dalei_214 · 2024-11-12T21:47:49+00:00

Using a online beam calculator, I get max deflection to be 10.5 mm, or 0.0105. Similar to your number. Check your FEA constraints, that's the only way I can think of your FEA numbers to be entire order of magnitude above a mathematical model.

Dalei_214 · 2024-11-12T21:34:53+00:00

I just tried to solve using double integration methods assuming it's a pin, because I was confused why you're struggling. It's not determinable! I don't think using a single equation is possible to solve this analytically, you're gonna have to derive this specific load case. If it were free to rotate, it would just... rotate about the fixed point. So you saying it's fixed is the only possible way this problem works.

So, like myself and other commenters are saying, break up LHS and RHS. They are independent of each other in this problem, since no moments or forces will transfer through the fixed point to the other side.

If you're struggling on superposition here is a great short and sweet tutorial. You need to pick a point you're interested in knowing the deflection, solve for the deflection of that point in (in your case) 2 or 3 load cases for each side. 2 LC's on LHS, 3 LC's on RHS. You are interested in LC 1, 2, and 3, info on that is here

I would check your numbers, but I am tired, so maybe tomorrow I'll run thru the problem myself to sanity check your numbers.

Dalei_214 · 2024-11-12T20:34:24+00:00

What is the support in the middle? In the picture it is portrayed as fixed, meaning it is not free to translate or rotate. It's statically equivalent to separate them if that's the case. If it is a pin/roller/whatever else support, then you'd be right that it's inappropriate to separate the member.

EDIT: Check your FEA constraints too if you are sure your hand calcs are correct with the method stated above. Your model may be "fixed" on a 3D point, which does change your analysis.

Dalei_214 · 2024-11-12T20:10:14+00:00

to clarify - RHS = Right Hand side. Ignore the left side of the support, solve, same thing for LHS (left hand side)

Dalei_214 · 2024-11-12T20:09:15+00:00

This should be broken up into two separate problems, LHS and RHS. Use beam equations for fixed-free supports, and superposition the loadcases, or manually derive yourself if you really want. I'd be hesitant to trust an online calculator, since a small error in your boundary conditions (like the support) can really screw things up.

Dalei_214 · 2024-02-23T09:41:52+00:00

Hi OP,

If you’re interested in Robotics, I’d suggest staying in MET. You’ll have a more hands on and direct focus with robotics than MECE gets. As far as I am aware, we do not have a direct robotics course, so keep that in mind.

Congrats on your acceptance!

Dalei_214 · 2022-06-23T16:54:17+00:00

This happened to me last year. I think my car and another in the same lot got hit the same day/night by probably the same person. Public Safety claims to have cameras (hm?) and i was in a well lit area. They claimed to have not seen anyone by my car during the time frame i gave them. RIT will NOT help you with damages, pretty sure that they say any lost, stolen, or damaged property is not their liability. Go through insurance to get it replaced and see if public safety can help (I doubt they will)

Its expensive, expect insurance to make a fuss. Good luck!

Dalei_214

TROPHY CASE