EVTOL... ultralight... I would like to discuss this with interested members

[justsomeguy]

Hello members... I need some help,

I am building an EVTOL that I designed to fit into the FAA ultralight category. I would like to get in touch with other members that have interest in this sort of thing and share/ pass along information on power systems, flight control systems/auto pilot, batteries, etc.
After building and testing three quarter scale prototype variations, I have started construction on a full-size prototype. All the CAD work for this design is now complete, and I have started the CNC work and the construction of the plugs for the full-scale body shell and panels, etc.
My background in aerodynamics, composite construction and plug / mold building makes creating the final Carbon Fiber shell and panels relatively straight forward. I however fall short in the knowledge of the electronics and flight control set up, etc. needed for its operation. The simplistic design takes off vertically and transitions into forward fight and then transitions back again for landing. It can also be flown as just a conventional aircraft with great short field capability.
Looking forward... I need to decide on the power system and batteries, flight control system/auto pilot and several other more general aspects of the build.
I am hoping there are members with an interest in EVTOL ultralights and we could all get together.
I look forward to hearing from you.

Steven

[FlyingRon]

Was that 3/4 scale or three different quarter scale prototypes?

[justsomeguy]

Was that 3/4 scale or three different quarter scale prototypes?

Hi,
I built 3 different, quarter scale (25% size)... prototypes...
Used a simple Futaba radio control system. It works fine for these small versions which proved the designs but the full size will need a commercial flight control system/batteries/ heavy lift power systems/auto pilot/redundancy, etc.. what I really need is to find a person or company that I can consult with on the areas I am not knowledgably in.

[FlyingRon]

You do understand about Reynolds numbers and the like? Power and lift do not scale linearly with size.

[justsomeguy]

You do understand about Reynolds numbers and the like? Power and lift do not scale linearly with size.

Yes, I am a mechanical engineer with a extensive background in aerodynamics. I have chosen a tried and true high lift (ultralight) airfoil with the stall characteristics where I need them and I am OK with the higher drag it has as I am not going for speed. My calculations and double checking with NASA calculations, for the final projected weight the stall speed in airplane mode falls within 18.2 and 20.4 MPH.
The aerodynamics, construction and flight characteristic are not where I need the help, it is the electronics, flight controls, batteries, etc. I have researched all of this and have found various sources.
I am in need of an experienced person to help me wade thru all the info, etc. and choose wisely...

Thank you for the response. I hope you can help me.

[spaceman]

Hi justsomeguy. The project seems to be very interesting, so can you share some photos?

[dougbush]

You might try the Lindbergh Foundation or VerdeGo Aero.

[BJC]

The aerodynamics, construction and flight characteristic are not where I need the help, it is the electronics, flight controls, batteries, etc.
The battery is the thing that everyone designing an electric aircraft needs help with. Currently available batteries just don’t have the energy density that most designs need. VTOL applications, even more so. Just consider the time, money and engineering expertise that has gone onto the Opener Black Fly, then look at its payload and range. https://opener.aero/pages/about-us

Good luck with your project.


BJC

[CHICAGORANDY]

It comes down to refined fossil fuel having about 60 times the energy per pound vs the current battery capability. And as fuel is consumed the conventional aircraft gets lighter, battery planes stay the same weight. No doubt viable AND competitive e-planes will be created one day, or powered by some other competitive energy source. But I suspect I'll never live to see that day.... maybe my 40+ yr old kids will?

[rwanttaja]

It comes down to refined fossil fuel having about 60 times the energy per pound vs the current battery capability. And as fuel is consumed the conventional aircraft gets lighter, battery planes stay the same weight.
I keep seeing this claimed as a major disadvantage of electric aircraft, but just don't see it. A typical one hour flight in my Fly Baby means the plane is ~3% lighter at landing than takeoff. Big whoop. Design-wise, it's actually an advantage...one no longer has to store the "fuel" along the center of gravity, nor take off with a plane whose CG changes in flight.

I keep imagining a newspaper editorial written in 1904..."The Wrights have invented a ridiculous form of transportation. Not only are the passengers exposed to the elements, they have to lie flat during the entire journey and not move, lest the machine become unbalanced. Though, admittedly, the journeys are short since the machine can only fly a few hundred feet. In comparison, a gentleman traveler may board a train in New York and arrive refreshed in Chicago a day later, enjoying a comfortable berth in a Pullman, dining luxuriously, smoking the odd cigar, a Wright aeroplanist and his ground caravan carrying gasoline, bamboo, linen, engines, and mechanics would be barely approaching the New York State borders."

Give 'em time, folks. There's a LOT of research going on to improve battery energy density, and it'll trickle down to aviation.

Ron Wanttaja

[lnuss]

An excellent observation, Ron. And look at the progress already made, both in aircraft and cars, and in the battery improvements (performance, safety, weight, space taken) in the last 10 years, 20 years, and more.

[steve]

Didn't Mercedes just test drive their new EV over 600 miles on a charge? I remember a coworker boasting he burned 0 gas driving his Nissan Leaf to work and home, a staggering distance of 36 miles. He could make it to work and back the next day, too. But he had better not forget to charge the car else he'd be walking to the bus stop on day 3. And that was maybe only 7 years ago.

[CHICAGORANDY]

I keep seeing this claimed as a major disadvantage of electric aircraft, but just don't see it. A typical one hour flight in my Fly Baby means the plane is ~3% lighter at landing than takeoff. Big whoop. Design-wise, it's actually an advantage...one no longer has to store the "fuel" along the center of gravity, nor take off with a plane whose CG changes in flight.

I keep imagining a newspaper editorial written in 1904..."The Wrights have invented a ridiculous form of transportation. Not only are the passengers exposed to the elements, they have to lie flat during the entire journey and not move, lest the machine become unbalanced. Though, admittedly, the journeys are short since the machine can only fly a few hundred feet. In comparison, a gentleman traveler may board a train in New York and arrive refreshed in Chicago a day later, enjoying a comfortable berth in a Pullman, dining luxuriously, smoking the odd cigar, a Wright aeroplanist and his ground caravan carrying gasoline, bamboo, linen, engines, and mechanics would be barely approaching the New York State borders."

Give 'em time, folks. There's a LOT of research going on to improve battery energy density, and it'll trickle down to aviation.

Ron Wanttaja

Ron, I do NOT disagree with or question your statements regarding weight shift. I ain't no pilot ner nuthin' - lol The available 'energy per pound' of "fuel" however remains the current chief stumbling block for e-powered flight vs fossil fuel. I was just watching a nifty YouTube about that 9 passenger all electric aircraft in the works. The reviewer made it clear that 9 passengers was the limit because of the nasty battery weight thing. The added weight of more available power to carry more than 9 would actually just be used to carry the added battery weight. here is the vid I referenced -

https://www.youtube.com/watch?v=b01nE83bmx8

Again, I have no doubt that 'someday' that wide gap between liquid fuel and the battery WILL move much closer to each other and make many of the present e-dreams a reality. But I'm 73 and doubt it will happen in my lifetime.

[rwanttaja]

Randy, I agree that the energy density in electric flight is the biggest problem right now. But your post was the second one I saw in a couple of days that claimed that "As fuel is consumed the conventional aircraft gets lighter, battery planes stay the same weight" is some sort of drawback, and am curious why folks think that's a problem.

We're not there *now*, and may not be there next year, but I'm suspecting the energy density issue will be solved, eventually. It's too important to a number of other fields, not just aviation. The automotive arena is the primary one; electric cars used to have a ~25 mile range, but are now commercially available with 400-mile ranges on up. And the infrastructure is expanding, with "quick charge" systems being added to major highways that give a pretty good boost to the battery in the time it takes to eat a burger and visit the rest room.

As to WHEN it's going to happen for airplanes? I don't see it as being much less than twenty years, which pretty much puts it out of the range where I'll be caring, too. Like many of us, I flew gas-powered U-control airplanes as a kid. A few years before I retired, a co-worker got me into small radio controlled aircraft using electric motors. These were stupendously easy to manage... no big old battery to heat up the glow plug, no hand propping, little noise, and easy throttle control. The little lithium packs were quick to swap out.

All the homebuilt accident studies I've been running have pointed out how much engine reliability affects the accident rate. Consider what has to work to make a reciprocating engine run...camshafts, valves, spark plugs, carburetors, mixture controls, carburetor heat, piston rings, pushrods, pistons jamming back and forth, etc. The entire structure has to withstand fifty gasoline explosions happening internally every SECOND.

You have to admire the engineers who can design something that'll handle that. But replacing it with a simple electric motor and controller is sounding like a better and better idea. Shoot, the airlines largely gave up on recips sixty years ago. Turbines are a lot better approach...but, sadly, require levels of precision that tend to eliminate them from consideration for small, light, inexpensive applications like most GA airplanes.

Just between us boys and girls, I think electric flight is going to be THE SAVIOR OF GENERAL AVIATION.

"Waaaiit a second there, Ron! Do you really think they're going to replace the engines in stuff like Cessna 172s????!!!"

Nope. But consider...what's the biggest immediate threat to General Aviation?

Why, the loss of airports, of course, and the reduction in hangar/tiedown areas.

Now, step into the Wayback machine to about twenty years ago, and the LAST big idea in personal transportation: The Segway. It was going to revolutionize transportation. No longer would you have to walk everywhere, you could hop on this little self-stabilized platform and zip down the sideways, driving directly into buildings and riding elevators to your destination.

What happened? Cities were appalled at the idea of these things mixing with pedestrians. They quickly passed laws keeping them off sideways, leaving only the bike lanes, walking paths, and polo fields available (true, Segway polo is a "thing"), and building owners forced the devices to be kept outside. Little advantage over a much-less-expensive scooter.

So...imagine what'll happen when the current set of personal air mobility devices hit the consumers. Will nextdoor neighbors tolerate the shrieking things leaving for the office at six in the morning? Will cities permit the multibladed devices to land willy-nilly on the streets or sidewalks?

Not hardly.

They're going to want to restrict the devices to specific operating areas, to isolate the noise, give room for operations, and provide storage/charging facilities for the devices kept there.

Airports, in other words. Sure, they don't need 5,000 foot runways, but that's what existing facilities have, and to catch on, the devices have to have places *now* that they can operate from and be stored. Any new airfields implemented aren't likely to have long runways, but the existing ones will be a godsend to the new technology.

So I'm hoping Black Fly, etc. help take off some of the pressure to close airports....

Ron Wanttaja

[Eric Page]

..."As fuel is consumed the conventional aircraft gets lighter, battery planes stay the same weight" is some sort of drawback, and am curious why folks think that's a problem.
The Holy Grail of electric propulsion research is a battery powered airliner. Let's do a thought experiment, using the Boeing 737-900ER, for which I happen to have performance data.

We climb to 35,000 feet and arrive at a gross weight of 180,000 lbs. We select a cruise speed of 0.79 Mach and hold that speed until we've burned 30,000 lbs of fuel and our gross weight is 150,000 lbs. As we fly along losing weight the aircraft gets more efficient, which the flight computer uses to reduce fuel burn rate at our constant speed. At level-off, burn rate is 6,842pph but at the end of the experiment it's only 5,554pph (with a 6% total reduction in power setting). That's a change in burn rate of 1,288pph or nearly 21.5 pounds per minute.

That advantage would not accrue to a hypothetical electric version of the same aircraft; over the course of our cruise segment example, weight remains the same so energy consumption rate cannot decline. To achieve identical payload, range and speed, the electric aircraft would have to have batteries with energy density better than that of jet fuel.

Whether you call that a petroleum advantage or a battery problem is up to you!

The next problem is an electric motor/fan no heavier than a CFM56-7B (https://youtu.be/KjYw0GdRpm0) that's capable of ~27,000 lbs of thrust.

[rwanttaja]

Good stuff, Eric.

However, I must gently point out that the subject line refers to ULTRALIGHT electric aviation. People are using the physics that hampers 180,000-pound airliners to justify why electric ultralights won't work.

Ron Wanttaja

[CHICAGORANDY]

Electric ultralight WILL of course "work". Until battery technology makes big improvements, they just can't work for very long. Flight time = battery weight

[rwanttaja]

Electric ultralight WILL of course "work". Until battery technology makes big improvements, they just can't work for very long. Flight time = battery weight

Certainly. However....

In the past 100 years, how much lighter is one gallon of gasoline?

In the past 100 years, how much lighter is a battery producing 40 kwh? :-)

Ron "Where's Moore when you need him" Wanttaja

[Eric Page]

...I must gently point out that the subject line refers to ULTRALIGHT electric aviation. People are using the physics that hampers 180,000-pound airliners to justify why electric ultralights won't work.
Yeah, sorry Ron. These threads do tend to wander a bit. My 737 example was in response to the energy density question raised in the WSJ video in post 13, above, and responded to a specific sentence in your post. I typed, then deleted a paragraph about how my example had little application to smaller aircraft (Reader's Digest: same physics, imperceptible effect). I should have left it alone, but I was trying to pare down a long post...

[rwanttaja]

....I should have left it alone, but I was trying to pare down a long post...
Shoot, dude...when has fear of writing a long post ever stopped ME? :-)

Your stuff is a pleasure to read, and I'm glad you bring your expertise here. It's a refreshing change from guys who say, "I'm agin' it 'cause Joe Smedlap on GoofyTheoryOfTheWeek.com says it'll curdle the milk and bring on global armageddon!!!"

Ron Wanttaja

[justsomeguy]

Shoot, dude...when has fear of writing a long post ever stopped ME? :-)

Your stuff is a pleasure to read, and I'm glad you bring your expertise here. It's a refreshing change from guys who say, "I'm agin' it 'cause Joe Smedlap on GoofyTheoryOfTheWeek.com says it'll curdle the milk and bring on global armageddon!!!"

Ron Wanttaja

Thank you for the info... I am glad to see there is interest in this and hope it will continue...

I based my EVTOL ultralight design on using an electric or hybrid electric power system. These power systems and battery systems are already in use with huge leaps forward being made constantly due to the Government back programs, current business ventures, start up companies and etc.. I have no doubt that this tech will trickle down to civilian aviation and ultralights. Not a question of "if" but "when" I would love to see this available to every individual ultra light enthusiast.
This design can operate (take off and land) as a conventional ultralight airplane or take off vertically, transition to conventional airplane mode and then back again for vertical landing or take off vertically and land as a conventional ultralight airplane. The construction of the full size prototype is moving along nicely with only some minor alterations needed so far. If you are reading this and know of any companies that offer flight controls, power systems, hardware, software, etc. pertaining to EVTOL operation... please pass it along. I appreciate all the info I can get. Thank you all again

[jimwalker]

Hello justsomeguy,

I am also interested in EVTOL (ultralight helicopters) and have expertise in power electronics but am lacking in the aerodynamics area. I am also lacking in knowing how to exchange information via forums. That is, how do I provide my email address or phone number without broadcasting it to China? I will be happy to help wherever I can.

[CHICAGORANDY]

"how do I provide my email address or phone number without broadcasting it to China?"

Hi Jim, if you click on anyone's underlined name just below the blue bar and date of a post, you will see the option to send a private message. Only the recipient will see it.

[Ethan Z]

I am a mere high school student with an overfunded science fair project, but I made a passenger-capable eVTOL hexacopter if you're interested in the documentation.

I wrote out a procedure for building it in my scientific paper here: https://docs.google.com/document/d/1cM39I1VCNBOc9mWQC_bJ6DQjGC9scLl6UB7-m9qH9pk/edit?usp=sharing

Ethan

https://lh4.googleusercontent.com/LyzckF_JJfVhgkF8vocZZMUBn_i4ikjBatM1SM6uRJgzzKI02M HGYDmhWW68EaRuvZtLaid1y_WIJ03OEr8qtHUIdbPuV-bcBb2EIWOtkawWmHZCefP4rTgbVja-MC7q2k_zA3uPlyWCpEI-YvavGlo

[saber25]

I read your 82 pages, or more accurately skimmed through them. They made my head spin about as fast as one of your rotors. I'm impressed and more so when you claim this is a science project in HS.

As an old Army helicopter pilot, I'm puzzled as to what mechanism is in place for a total propulsion failure and how the pilot would handle that when you are at an altitude higher than what you would feel safe falling from. I'm certainly familiar with the procedures in single and dual rotor helicopters but I see no relationship to those emergency procedures relative to a hex or even quadcopter. You cite an example of two motors failing on opposite sides and the control algorithm handling that but what if you had two go out adjacent to each other on a hex configuration? Is the plan to install a BRS to mitigate partial or complete thrust failure?

I wish you luck and no doubt you'll be going places :)

[saber25]

Actually Ron, this statement "In comparison, a gentleman traveler may board a train in New York and arrive refreshed in Chicago a day later, enjoying a comfortable berth in a Pullman, dining luxuriously, smoking the odd cigar, a Wright aeroplanist and his ground caravan carrying gasoline, bamboo, linen, engines, and mechanics would be barely approaching the New York State borders" doesn't sound so bad in view of what's been happening to air travel. I started in the industry in 1965 and knowing what I know now wouldn't recognize what the Egalitarian Airline has turned into.

[rwanttaja]

Actually Ron, this statement "In comparison, a gentleman traveler may board a train in New York and arrive refreshed in Chicago a day later, enjoying a comfortable berth in a Pullman, dining luxuriously, smoking the odd cigar, a Wright aeroplanist and his ground caravan carrying gasoline, bamboo, linen, engines, and mechanics would be barely approaching the New York State borders" doesn't sound so bad in view of what's been happening to air travel. I started in the industry in 1965 and knowing what I know now wouldn't recognize what the Egalitarian Airline has turned into.

My dear Saber, there's a rather easy cure for that. Let me describe my typical airline flight:

I arrive early at the airport, due mostly to ground traffic and parking difficulty.

When I check in with the airlines, I bypass the long lines and go to the ticket counter with only a few people waiting. I usually check my bags, since I hate lugging them all over the airport. No charge to check the bags.

Going to the gates, I only have a couple minutes wait in the TSA line, and don't have to remove my belt or shoes (TSA Precheck).

Got time before the flight? I typically fly Alaska, and they have a free separate waiting lounge. Free breakfast/snacks, free coffee and soft drinks, comfortable individual chairs (not the long attached string of hard plastic seats), free WiFi. Service staff available, clean restrooms.

Stroll out to the gate when flight time comes. Always the first non-family, non-handicapped group to board. Overhead bins are wide open. Sit down in a well-cushioned seat, typically 21-22 inches wide instead of the usual 17. No chance of a center seat; just aisle or window. Legroom is about 36 inches, about six inches more than normal...if I stretch my legs, my ankles touch under the seat in front of me. Overhead bins are large; almost never have to tuck anything under the seat in front of me.

The flight attendant offers me a free drink, and I happily take it. One leaves a cup of nuts on my tray. One FA for about 24 passengers, vs the normal 50 or 60 passengers per FA. We've got our own bathroom, too. The pilot occasionally will come back and chat. After takeoff, there's a choice between two free meals, still with free drinks. Meals sometimes include a hot chocolate-chip cookie.

After landing, I'm nearly the first one off the airplane. Bag is usually one of the first to reach the carousel, typically with a "PRIORITY" tag attached.

The secret? Most people pick their flights based on the cheapest airfares. I pick mine based on the most comfort.

Yes, I'm describing flying first class. Sure, this might be similar to the description of coach-class travel in the '60s, but back then, you paid the EQUIVALENT of today's first-class airfare to get on the airplane.

Next trip you take...look at the first class fares. I've found for some airlines, the first class ticket can be as little as $200 more than a coach class. Delta is an especially good value for first-class fares...I once snagged one for only $80 more than coach. Delta doesn't have the free first-class lounges that Alaska does, though, and the Alaska first class fares are a bit more.

Most people aren't willing to PAY for comfort. Airlines cater to these folks by cramming seats together, charging for baggage, and cutting out amenities. The people flying get what they say they want (cheap air fares) but complain about the environment. It's like someone eating at McDonalds and complaining that the Filet Mignon was dry and tasteless......

Ron Wanttaja

[saber25]

Touche Ron,

You describe what it used to be while flying on a pass as an employee many years ago. Having spent a career flying ahead of first class however, I've noticed a steady decline in passenger civility which isn't always reflected by the cost of a ticket. Years ago while deadheading on a DC-10 in first class, the moron sitting next to the forward bulkhead dressed in baggy shorts, flip flops and tank top, rested his hairy feet up on the bulkhead for the rest of first class to admire for the remainder of the flight.

Getting back to the subject of electronic flight, it'll be interesting to sit in on the Captain's briefing concerning extra battery capacity to handle anticipated holding and perhaps deviation to the far off alternate. I know, I've had that discussion with my crew when it came time to add to the dispatch fuel because their weather prognostication seemed a bit too optimistic.

"Check six" Saber 25.

[Ernie]

Moving on to electric helicopters :) I am really interested in the MiroCopter, will likely buy one after I have had a chance to examine it in detail. I have spent some time thinking about the challenges of making it electric. Aside from drive and structural changes, the motor control needs to be customized to take into consideration the torque control required to engage the rotors without damaging them. Electric motors have maximum torque at about zero RPM and accelerate quickly with no or minimal load. Rotor systems have a lot more mass than props, wear items, and things like dampers to reduce shock on the blades. Torque needs to be controlled by the motor controller not the pilot.

[FlyingRon]

Didn't Mercedes just test drive their new EV over 600 miles on a charge? I remember a coworker boasting he burned 0 gas driving his Nissan Leaf to work and home, a staggering distance of 36 miles. He could make it to work and back the next day, too. But he had better not forget to charge the car else he'd be walking to the bus stop on day 3. And that was maybe only 7 years ago.

I used to drive a Volt. It had just barely enough range to make it from my house to my hangar at CJR. I knew I was driving efficiently if I got there on the battery charge. Drive a bit too fast, and I wouldn't make it. I'd pull the plane out, put the car in and let it charge while I was gone. Then I'd have enough to see if I could get home.

[Airmutt]

Good job Ethan, you’re gonna make one helluva an engineer.