# Engine options for my Lazair

### Help Support HomeBuiltAirplanes.com:

#### Noeson

##### Member
Started my own thread on affordable engines for Part 103 ultralights because I am veering into weirdo rc airplane and electric territory:

I have a 142 lb Lazair with 2 x 5.5 HP engines and a 400 lb MTOW and I am not eager to fly it until I get more power. The only good reason for me to go with a gas engine is range, but with a 5 gallon max tank for ultralights that advantage is limited. I can see why a handier person would want to go with gasoline but for me and my limited skills it's a rabbit hole. For a LSA it's an intriguing solution though!

Saito engines run about $120 to$150 per HP and per lb, including mount and muffler.

or the twin 100cc:

An ultralight would need 2+ of these engines, but that's a feature and not a bug when flying experimental aircraft, no?

But for my plane: Roto Max 150s looks like my best option at the moment and that leaves 100+ lbs of useful load for a 22 lb chute and 8-10kwh of batteries. My Lazair is lighter than the model Dale Kramer electrified and I weigh 150 lbs give or take a cheeseburger, so I am maybe 100 lbs ahead of e-Lazair already. A 4kw cruise seems doable.

In the rc airplane world guys are getting a legit kw per 50 square feet of solar cells, Lazair wing area = 144 sq ft., plus tail assembly Why leave up to 3kw on the table? Solar should be part of the drivetrain solution. If I could get half of the 4kw I need to cruise from solar then my 10 kwh battery pack is going to give me some pretty good range!

Back in the day Dornier used 2, 3, 4, or even 12 engines because he was designing with unproven emerging technologies and scarce resources and I think that applies today with electric. An array of motors may be preferable in development to an all eggs in basket single motor.

The best off the shelf complete drivetrain I am aware of is Chip Irwin's for the Zigolo but it costs $17,500: Zigolo – Aeromarine-LSA • Battery Packs: 2 x 3.1 kwh 14S/20P/15KG, 60Ah • Motor: 20kW continuous, 28 kW peak, low noise, low RPM I am just spitballing here, comments are welcome. #### TFF ##### Well-Known Member I doubt the Saitos are going to be powerful enough. Not direct drive. Two 100cc two strokes would probably do it. At the RC field last week, someone was breaking in one of the radials on a Corsair. Pretty sweet engine. #### pictsidhe ##### Well-Known Member Give or take a cheeseburger, you are indeed an ultralight pilot Start with Farfle's electric Belite thread. Peter Sripol's YouTube biplane is a must watch for you. Good idea picking the lazair as the base, that starts you way ahead of Farfle and Peter... Solar panels tend to be heavy. There are some semi- flexible ones out there. You might be able to use them and get 70sqft of solar. The flexible ones aren't particularly light, either. It is possible to make very light composite panels. But making solar panels is no easy task. I'd be inclined to have at least a 200W panel, just so it is getting topped up should I stop somewhere for lunch. Or maybe I get my range calculations wrong. Land and wait... #### Victor Bravo ##### Well-Known Member HBA Supporter All of this depends on whether you want to fly at the least possible weight, or cost, or the highest reliability, or the least noise, or if you are trying to save the planet by using a combination of COAL powered electricity and child slave labor in Lithium mines. If you want to enjoy flying your Lazair the soonest and with the greatest reliability, I'd have to say two of the smallest modern paramotor engines, selecting propellers to limit the RPM, will give you a fantastic combination of takeoff, reliability (less engine load) and fuel economy. #### pictsidhe ##### Well-Known Member All of this depends on whether you want to fly at the least possible weight, or cost, or the highest reliability, or the least noise, or if you are trying to save the planet by using a combination of COAL powered electricity and child slave labor in Lithium mines. If you want to enjoy flying your Lazair the soonest and with the greatest reliability, I'd have to say two of the smallest modern paramotor engines, selecting propellers to limit the RPM, will give you a fantastic combination of takeoff, reliability (less engine load) and fuel economy. Come on VB, California is one of the last big users of coal fired electricity. Locating the the dirty stuff 20 miles out of state only makes the issue go away legally. Many states have significant renewable power as well as using the less toxic gas. #### Noeson ##### Member All of this depends on whether you want to fly blah blah blah coal satan child slave labour etc etc Yeah maybe speaking to people on the internet was a bad idea today. I just don't enjoy this type of comment. #### Noeson ##### Member THIS ISNT A POLITICAL AIRPLANE OR THREAD PEOPLE I just want a plane that won't kill me. No, I'm not some granola coming here to petroleum shame you. #### pictsidhe ##### Well-Known Member THIS ISNT A POLITICAL AIRPLANE OR THREAD PEOPLE I just want a plane that won't kill me. No, I'm not some granola coming here to petroleum shame you. Bad news, ANY plane can kill you! VB does have a point, bolting on a pair of already sorted petrol engines is likely the easiest option. I'd like to see somebody do an electric conversion that can actually leave the pattern, do maybe I'm steering you a bit. The Lazair is a far better platform than a Belite or foam biplane. VB's also not usually so overdosed on granola. He's been flying a C***** 172 for a long time... #### Noeson ##### Member Are we certain that gas engines are more reliable, or easier, or less expensive, in this instance, than available alternatives? What data informs this? Where is the data showing electric motors to be more complex, less reliable, or less expensive than the gas option here? Mike Sandlin's Bloop has used a Moster paraglider motor for years and it runs relatively well, by which I mean he often has problems with it - it's stated right there on his webpage. And is any two stroke going to be any better? I'm horrified by these engines, that's specifically why I bought a twin engine plane. What I don't get is that my Dad's 6HP Evinrude outboard has run solid for 55 years now, never cuts out, never a problem. I have an Onan generator in my RV that runs fine and Onan is what powered Rutan's earliest planes. So gas engines aren't necessarily the problem here. Snufflupagus is real, I've seen him (4 legs, shaggy brown hair) but where is the mythical reliable two stroke ultralight aircraft engine in the 15-50 hp range? I like the idea of flying somewhere far from d-bags like Vic Bravo here and being able to fuel up via the sun for weeks at a time. Maybe the arctic in the summer, where the sun doesn't set and I can get (albeit low power) solar power all day and night. Effectively it is a douchebag avoidance device, but there is commercial potential in the natural resources sector since it can be "out in the field" indefinitely. #### Protech Racing ##### Well-Known Member The twin 212 briggs seem to fly those well. #### poormansairforce ##### Well-Known Member Mike Sandlin's Bloop has used a Moster paraglider motor for years and it runs relatively well, by which I mean he often has problems with it - it's stated right there on his webpage. And is any two stroke going to be any better? I had a Kaw 340 in my Minimax and have currently a 100 hp engine in a waverunner and neither has ever missed a beat. The spark plugs in the waverunner are 4 years old and no carbon! The magic is fresh mix, quality oil, clean filters, and good storage habits. We also have 2 outboards with no troubles and using the same spark plugs for several years. What I'm saying is it takes really good habits especially on a highly-tuned two-stroke when they're trying to get every bit of horsepower out of it to save weight. I think on most of these it comes down to what type of carburetor they're using. #### Victor Bravo ##### Well-Known Member HBA Supporter THIS ISNT A POLITICAL AIRPLANE OR THREAD PEOPLE I just want a plane that won't kill me. No, I'm not some granola coming here to petroleum shame you. You incorrectly mistook a mildly smart-assed comment for a political comment. There was no political motivation or statement being made, and you're mistaken if you read politics into it. I was just barely making fun of the granola bars, but not trying to drive public opinion for or against them. I was only pointing out that the people who make such a big deal out of electric power systems (based on carbon footprint, emmissions, ozone layers) often don't think about where that power comes from. On balance, I have actually spent a fair bit of time flying "green" airplanes with zero carbon footprint, so I'm not the opposite of the granola bars either. No 3 ton V8 powered SUV's in the driveway here, but no Prii either. I like breathing air as much as the next guy. I stand by the position that my comment was not political OR smart-assed enough to justify anyone getting hot under the collar. #### Victor Bravo ##### Well-Known Member HBA Supporter VB's also not usually so overdosed on granola. He's been flying a C***** 172 for a long time... Can somebody please un-handcuff me from this tree? Honest, I'll take the catalytic converter off my car, I promise. I'll have you know that mine is just about the most un-granola 172 you could have. A '56 straight-tail, 35 pound rear seat removed, two vacuum venturis and 15 pounds of old '50s junk gyro instruments removed, some home-made gap seals, a bit of hangar rash, plenty of faded paint, a flap control STOL mod of my own invention... and I just bought a 310 nose fork to put a bigger tire on the front to go off-roading in the desert. Why... I'm almost as bad-ass as those white collar Wall St. accountants that put on a wanna-be leather vest and take their Harley's out to Starbucks after work! Last edited: #### Speedboat100 ##### Well-Known Member Zenoah, DLE, ZDZ or DA engines...100-170 size. #### pictsidhe ##### Well-Known Member Can somebody please un-hancuff me from this tree? Honest, I'll take the catalytic converter off my car, I promise. I'll have you know that mine is just about the most un-granola 172 you could have. A '56 straight-tail, 35 pound rear seat removed, two vacuum venturis and 15 pounds of old '50s junk gyro instruments removed, some home-made gap seals, a bit of hangar rash, plenty of faded paint, a flap control STOL mod of my own invention... and I just bought a 310 nose fork to put a bigger tire on the front to go off-roading in the desert. Why... I'm almost as bad-ass as those white collar Wall St. accountants that put on a wanna-be leather vest and take their Harley's out to Starbucks after work! Hug the tree, VB. Think happy thoughts. Such as cutting it down and turning it into an aeroplane #### TFF ##### Well-Known Member Actually it’s granola on the repurpose scale. Crunch crunch. #### Doran Jaffas ##### Well-Known Member All of this depends on whether you want to fly blah blah blah coal satan child slave labour etc etc Yeah maybe speaking to people on the internet was a bad idea today. I just don't enjoy this type of comment. Aside from the part of the comment that you did not like he was talking good sense when it comes to getting a good reliable engine from a glider and installing that. I have been around ultralights and I remember the Lazair when I first came out. I believe it was a couple of two-stroke 8 horsepower engines and they worked fairly well. They might have even been less horsepower than that. Once I saw the single engine conversion I thought that had real promise. The Lazair is a beautiful airplane especially when there's a pod hung underneath. They have a very high lift to weight ratio and I wouldn't mind owning one myself all these years later. If you'd like to talk more about this and some possible power plants feel free to give me a holler on here and we'll figure out a way to connect in a more private setting. I currently own a Tailwind W8 with the 108 horsepower Continental and it is a beautiful flyer but I have always admired the Lazair. Doran Jaffas N625MS Y70 #### paraplane ##### Active Member Lazair is one of the neatest Ultralights in my opinion. I have been interested in acquiring one. I've seen them sell with a need to be recovered for 1,000$ The templates for wing ribs and plans are available. When you re-cover consider heavy model aircraft covering materials. Considering model airplane engines and various parts is no weirdo thing. If it works why not. Here are links to a couple videos.
The first video is a repost of the original. The second is one of my favorite aircraft designers if you watch another video of another aircraft he designed you will see that he uses rc aircraft covering film and if I remember correctly in the video with the interview on Woodpecker I think its mentioned a rc model flight controller is used as an autopilot. Go electric I say if you can afford. If it was possible in the 70's with the first Electric Plane a Solar power Easy Riser Ultralight how much more possible now? The potential cost is going to be in battery. Lithium Ion has more energy density than Lithium Polymer from what I understand. Perhaps source youre cells from totalled Testla cars if you can find them. That's if you wouldn't shy away from or enjoy working more than less on the project. Good luck.

#### jedi

##### Well-Known Member
.........

What I don't get is that my Dad's 6HP Evinrude outboard has run solid for 55 years now, never cuts out, never a problem. I have an Onan generator in my RV that runs fine and Onan is what powered Rutan's earliest planes. So gas engines aren't necessarily the problem here.

Snufflupagus is real, I've seen him (4 legs, shaggy brown hair) but where is the mythical reliable two stroke ultralight aircraft engine in the 15-50 hp range?

........
70 degree lake water does wonders for engine cooling. Other applications like the Onan do not run continuous max power.

Don't abuse it if you want to continue to use it.

#### akwrencher

##### Well-Known Member
HBA Supporter
A quick study of outboard HP per litre will show that the average outboard is rated for roughly half what a rotax is rated for. A 20-35 HP Evinrude from back in the day, was, I think, aroun 537 cc, give or take. A 65 HP rotax is 582cc. That's part of the equation.