Need opinions for electric aircraft project

[wilson10]

Hello, I am currently working on a capstone project for my bachelor's degree where I have been added to a team of aerospace engineering students tasked with designing a lightweight VTOL aircraft. The parameters of the project imply that fully electric or fuel powered helicopters will not be able to meet the demands, so a hybrid system in an unorthodox aircraft is essentially required.
Now that I've introduced the project, the thing I would like expertise on is a concept I saw on the Alpha Electro, made by Pipistrel LLC. This aircraft uses the propeller as a wind turbine when descending to charge the batteries.
I have very little experience with power generation in general but have been told that turbines are very tricky to work with and control, becoming dangerous and destabilized if not handled properly.
What kind of systems would need to be in place to control RPM without destroying the propeller or placing extra wear and tear on parts?
Thank you in advance
https://192-168-2-1.link/
http://tplinklogin.info/
https://192-168-1-128.link/

 

[leaded50]

wind turbines biggest problem is the bearings, if its "direct drive", or through gearbox.(eg. heat)
A propeller on a plane do rotate at given prm by motor power, and if should rotate without the power, just by windforces , i believe it will rotate slower...at least does by a electric RC plane. Adjustable pitch on prop to control RPM vs speed isnt unusual on prop planes..

Im not any aviation expert though, neither on wind turbines. This is my thoughts about what learned, or heard persons in such businesses says.
Why dont rather think about solarcells to charge in flight? It will be more easy to incorporate in a plane.

 

[JasonK]

How big is your project - physical size target?

I doubt your going to get regenerative breaking working well without variable pitch. Nor do I expect that you would recover enough power to be of note by doing regenerative breaking of of the prop like that (at least at typical RC scale - the reference said up to 13% with all of their engineering skill behind it).

You also mentioned VTOL, which typically means a powered landing vs a regenerative breaking landing (which is what the Alpha Electro appears to be doing to recover that power).

To me, it sounds like that they are looking for something like this (based on your limited details, this is my first though on how to meet the apparent requirements):
Fuel powered motor -> generator -> batteries -> Electric motors for thrust (both lift and forward)
given that forward flight can use significantly less power then hovering, you can take off/land on power from the batteries. In cruse, the fuel powered motor can supply more power needed, so it will be recharging the batteries during flight.

IIRC, if your running a motor just as a generator you can tune/run it at a much higher efficiency then if it needs to have a wide operating envelope.

 

[CappyAmeric]

Maybe a perpetual motion machine?

Seriously, it depends on what is supposed to be achieved.

The energy extracted and stored from a descent with a free spinning turbine would be minuscule compared to the energy expended to ascend. VTOL makes the formula even less viable.

 

[quorneng]

wilson10
I doubt any one could just sit down and design such a craft. There are far too many unknowns.
If my degree project was anything to go by it is the how you go about it that is more important than any results your might achieve. You have to accept there are a great many minds working on aerodynamic projects. If there is an easy and practical solution to a problem the odds are it would have been identified already.

So without knowing the details of the project parameters my suggestion is to find out how much electrical energy is used to vertically lift off a say a 5 lb (2kg) helicopter to a safe altitude.
Then how much electrical energy can be recovered from a wind turbine type prop driving a generator when a 5 lb plane is flying straight and level.
It might take quite a bit of library or internet research to arrive at any figures.
Like JasonK my feeling is it would show that you might have to fly for many hours to generate & store enough energy for a single VTOL.

My guess is that a careful examination of the project parameters would actually reveal the path of likely solutions.
I may be wrong but to me what you have described so far simply defies known aerodynamic understanding.

 

[Piotrsko]

I would suggest a divorced power autogyro with a powered jumpstart, but like @quorneng said it will be a lost energy system with paltry returns of energy. The turbine is the least of the issues since it is the associated transmission that absorbs stresses.

Current thinking on electric power vtol indicates you just need lots of batteries or deal with short flights. You also cannot recharge as fast as you discharge.

 

[Merv]

...The parameters of the project imply that fully electric or fuel powered helicopters will not be able to meet the demands, so a hybrid system in an unorthodox aircraft is essentially required....

Just a little more information on the requirements would be helpfull.

Would an onboard liquid fuel generator, supplying power to a battery, which powers an electric VTOL or quadcopter meet the requirements?

 

[Flightspeed]

Why bother, he hasn’t been in like 8 months, I doubts he’ll see that