Getting back in

Full Size

Nothing new right now, just wanted to take a moment to re-present the electric helicopter in full size.

Side bar flush November 2009

11/30/2009: Waiting for poll results.
11/29/2009: Sunday.
11/28/2009: More doing, less announcing.
11/27/2009: Recovering from eating all day yesterday.
11/26/2009: Eating all day.
11/25/2009: Family in town, yay!
11/24/2009: Climbing back in, I think.
11/23/2009: New sketch is up.
11/22/2009: See today's post for update...too much going on.
11/21/2009: Unveil today!
11/20/2009: Unveil tomorrow.
11/19/2009: Unveil due this week. Stay tuned!
11/18/2009: Big things lie ahead!
11/17/2009: No update.
11/16/2009: Planning the next steps. Testflight anyone?
11/15/2009: Resting.
11/14/2009: The helicopter is done!
11/13/2009: TGIF.
11/12/2009: Just posted an update regarding some techical detail.
11/11/2009: Next step is to finish up the main rotor, connect some wiring, and then we can think about taking flight.
11/10/2009: Now we can control the helicopter and use software to manage the e-motors.
11/09/2009: Sketching in progress, post is imminent.
11/08/2009: Next steps are brought to paper.
11/07/2009: I think I need to come up with a publishing schedule.
11/06/2009: The main nut to hold the tail rotor in place goes on.
11/05/2009: Collective pitch will be manual, but main rotor rpm will be computer controlled.
11/04/2009: Missed the daily update. Darn.
11/03/2009: Long day at work.
11/02/2009: Added a subscribe and a share gadget to the sidebar.
11/02/2009: Tail rotor assembly is complete.
11/01/2009: Sketching continues on tail rotor.

World Premiere

So far so good. The e-copter is done for now. Next steps? Please vote on the right.

Ready? Or how to buy more time.

The plan for presenting the e-copter is finished. The sketching not so much, obviously. ;-) Well, I don't have too much time these days, but I like where the plan is going and hope that the results will be as good as expected. I also think it's time to get some feedback from you guys as to what the next steps should be. Prepare for web poll number 2.

Delay

Job #1

With all components installed and the wiring hooked up to the laptop, I call it a day for now. This is really job number one and the first flying prototype united in one physical vehicle. Let's see how it does.

Some detail

For me and the techies out there, here a bit more detail regarding how the main rotor pitch will work. Each blade can be turned around it's longitudinal or radial axis individually, via a servo, which is controlled by the laptop we installed a while back as the main control unit. You have to look at the large scale image if you want to see the details. I also implemented a software based rpm control. Once the sensor in the e-motor notices an rpm decrease (for example caused by increased pitch angle leading to increased drag leading to lower rpm at the same torque) it sends a signal to the laptop, which in turn sends a signal to the e-motor to request more torque and bring rpm back to where it should be. At the same time (and this is not shown) battery temperature, state of charge, voltage are also monitored by the laptop.

Controls

Done practicing. A little bit of sheet metal to manufacture the combo bracket, that holds the main control unit and the HEI and will attach to the forward bottom edge of the airframe.

If that sounds too much like some fancy h-e-licopter lingo, here's the translation:
1) main control unit = laptop
2) HEI = human-e-copter-interface /controls = joystick
3) airframe = office chair

Simulator

Just practicing helicopter flight in Flight Simulator. With this joystick, collective pitch is done via the throttle lever, cyclic pitch is done via the main stick, and tail rotor pitch is done via twisting the stick around it's vertical axis. Hmm, makes me think...Anyway, gotta sleep now. It's already late.

Last Nut

With the tail rotor main nut secured it's time to start planning out the final steps before the maiden flight can take place. I'm thinking we will need a control unit, controls, and a charger. As promised, I also came up with the solution for the cyclic pitch. This requires an Ikea salad bowl, but that's not an issue at all.

Fixed pitch tail rotor

The e-motor for the tail rotor got attached to the rear tail boom bracket with two bolts. Wires got soldered to the e-motor, feeding through the tube forward to the power distribution box. Which is not yet finalized. But this box will take power from the main rotor battery and divert it back to the tail rotor as needed. The tail rotor is a fixed pitch design and its rpm can be controlled independently from the main rotor rpm.

Side bar flush October 2009

10/31/2009: Happy Halloween!
10/30/2009: Just relaxing.
10/29/2009: Electronic solution for cyclic pitch is on paper.
10/28/2009: Rear e-motor assembly in the works.
10/27/2009: Just after midnight (pacific time), the tail section got bolted onto the fuselage.
10/26/2009: Drawing is in progress...
10/25/2009: Some minor improvements to the setup of the blog.
10/24/2009: Not happy with the progress right now. But getting there.
10/23/2009: Well, just after midnight, blogger is back up. And finally an update.
10/22/2009: Done sketching. But blogger is down, so no posting.
10/21/2009: Electronics will be the key to make it fly.
10/20/2009: Fully articulated rotors are unlikely. But the first sketches are on paper.
10/19/2009: I heard that "my character" is thinking about changing his name.
10/18/2009: Found a book on helicopters and started reading up on the various rotor head designs out there...
10/17/2009: The scanner is back up and running, so what am I waiting for?
10/16/2009: Started to move things around and pick the daily updates back up.

Tail boom assembly

It was about time to think through and start the tail boom assembly. Picture one explains it all but let me walk you through. So the big tube will be equipped with two brackets. One in the rear to hold the tail rotor e-motor to the tail section, and one bracket in the front that will hold the whole tail section assembly to the fuselage (office chair). Some bending, drilling, and welding is involved. All these single parts are aluminum, by the way. The tail rotor will be powered by a small e-motor, specs to be released later. It will be a fixed pitch propeller, which is not finalized yet. Picture two shows the night shift I pulled to get the welding done. In picture three, the tail boom gets bolted onto the fuselage. Picture four shows that work is done for today. Good night...

Minor changes

Quick note from behind the scenes. By looking at other blogs I noticed that it's mostly not immediately clear what the blog is about. Very inconvenient. If I don't know what's going on within 5 seconds, I leave right away. To avoid this for my visitors, the title bar on this blog now clearly and exclusively states the title and objective of the blog. The old text from the title bar has moved to the side bar.

Ease back into work

Side bar flush September 2009

And, here's the side bar flush for September!
...eeehm...
...well...

-0-

Side bar flush August 2009

Here's all daily updates from the month of August 2009. I think a monthly flush of updates into a blog post will serve us well and keep the side bar neat and clean, while not loosing the content all together.

08/25/09: In the middle of a fairly unexpected move across the US.
08/18/09: An update is highly unlikely today.
08/17/09: Had a few minutes to revisit the center-of-gravity.
08/16/09: Note to self: clarify how the undercarriage was re-assembled to fix the center-of-gravity issue.
08/15/09: Too much going on. Need to postpone sketching.
08/14/09: Readers demand a fully articulated rotor head design. Luckily I incorporated some features in the early design. Working on it.
08/13/09: Lot's of things going on. Wasn't able to think straight let alone come up with a new sketch.
08/12/09 pm: I added RSS feed and plan to implement some tweeting.
08/12/09 am: Did manage to cut some time out for sketching. Couldn't wait to see the main go onto the e-motor.
08/11/09: Promised too much. Stressed out and tired today.
08/10/09: Not sure if I will get something on paper today, but tomorrow at the latest.
08/09/09: In the mood to see the main rotor assembled onto the e-motor drive shaft.
08/08/09: Tired but managed to sketch a few things and manufacture a new post.

4 weeks of nothing

After almost 4 solid weeks of sketching sleep-mode (or to put it bluntly a whole lot of nothing, zero, niente...well at least from the reader's perspective) I start to THINK about picking things back up where I left them. How about I introduce the daily updates in the bar to my left (your right) for now so I can re-connect with the site mentally and pick up the pencil again. Stay tuned and THANKS FOR YOUR PATIENCE!

Arrived

I've arrived at my new location in California. What a great environment to relax with some sketching and come up with new ideas! Once I have settled in a bit and my scanner is back up and running, I will continue the story!

Moving

Message from the guy behind the pencil: Dear Reader, I'm about to move across the country for work. I've disassembled my computer equipment including the scanner and will not be able to post anything in the coming week or two (on laptop right now). Once I'm set up, I will resume blogging. I will miss it. But believe me, the story continues to evolve in my mind. Stay tuned! This thing will fly! Best, Axel

SUMMER BREAK

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Flashback

Rewinding real quick to where the center-of-gravity (CG) problem was fixed. This is what happened back then and how the CG was brought under control. Next steps will be to come up with some electronics, software, and controls. Thinking about it.

ROTFL!

Pulled a late shift to get some stuff done while I can. You never know how busy the times ahead will be. After gluing the last batteries in place and feeding the wires through to the end, I let the glue dry over night. Then assembled to the blades to the head and bolted the close-out plates on. Three bolts each suffice. The rotor head is fixed to the e-motor shaft, which is a tailor-rolled sandwich tube for optimal torsion stiffness. The sandwich material enables feeding the positive and negative sides of the battery down to the e-motor. Connection established. Finally, big step! Got the main rotor onto the e-motor shaft. Now I'm tired...

Tile

Not quite there yet, it really seems like helicopter manufacturing takes longer than you think. At least the batteries are now attached and the three rotor blades take shape.

Finally

Today, the profiles (leading & trailing edges, main spars) arrived, as well as the batteries. The next steps will be assembling the aluminum profiles to the end plates and then applying a process called structural bonding (superglue, blue glue, or similar) to establish a structurally sound connection between batteries and profiles. Batteries do tend to emit heat during operation, which I will counteract by naturally air-cooling them.

Nervous

Getting ready to put the order in for the LiPo batteries. After confirming the size, weight, and capacity, I think I will be fine with 336 batteries. I will order 360 anyway, just in case. Plus changing the BOM will require so much effort. I'm an engineer not a paper-shuffler. Also got some drawings for the leading edge, spar, and trailing edge. End plates are necessary too. Plus 9 bolts to fix the end plates to the structural profiles. Stuff starts to come together.

Sub-Assembly BOM

With the CG under control for now, it's time to start thinking about the rotor assembly. Since it's always good to think before taking action, I made up a bill-of-material for the main rotor assembly. I also made a few first sketches to lay out the overall rotor design. Stay tuned for updates.

CG problem solved

I did a quick initial weight-and-balance check on a paper napkin and found that the undercarriage has to move back to keep things balanced. Easy fix though. Just need to turn around the base plate of the chair and we're ready to move forward.

McGuyver

Need to do some custom precision one-axis non-cnc bending and aluminum welding to make the brackets that will fix the engine to the main structure. No problem. Can-do-attitude.

Marriage

This electric motor I got out of my dryer weighs about 60 pounds or so. Seems heavy at first, so I left it on the workbench. This is almost like a classic marriage, where powertrain and body assembly are coming together.

Start Of Production

The office chair has done so well in testing the other day, that I decided to use that as main structure, chassis, fuselage, landing gear, and seat, of course. A picture is coming together in my mind. Let's drill some attachment holes first and then go from there.

Zzzzzzz zzzzzzz zzzzzzz

This seems like the way to go...a simple electric motor with a rotor...steering done by weight shift method...i like that electric thing...what about anti-torque though...and flight controls...zzzzzzz...

Practicing

Hovering is so easy! So with the training out of the way, let's get some materials and start putting stuff together.

Working on it...

Reading up about homebuilt helicopters. There are quite some exotic concepts. Most of them use a combustion engine or turbine of some sort. Not convinced that that's the way to go in the 21st century. Will have to do some more thinking.

Poll 1 Closed.

The vote is closed. Thanks everyone for voting, you're awesome! 13 people voted. I will go build a helicopter tomorrow. Meantime I have to come up with a plan...Does anyone know how to build a helicopter?

Birthday!

Hi! Today's my birthday. Just let me know what I should do. And I will go off and do it. Simple.

Poll on the right closes: 7/17/09 noon EST