Post by voltekhybrid on Aug 5, 2021 0:13:29 GMT -5
Hello yal!
It's been so long since I've been on here I couldn't remember my username and had to make a new one! Anyways, just wanted to share a little about a project I've been working on but haven't touched in nearly a year: the motorjet.
Ever wanted a jet engine without all the hassle of high RPM parts? Well then, The Motorjet may be right for you! At the most basic level, a motorjet is a reciprocating piston engine attached to a compressor with an afterburner; very simple. You could also add a turbo to compensate at higher altitudes or even add an additional combustor so that the turbo could function as a gas generator.
Doing some research on this I found that motorjets were actually the first kind of jet engine to be flown. This was before we had good enough metallurgy to make turbine blades that could survive high heat, RPM and vibrations. Once that problem was solved, the motorjet fell to the wayside. I'm picking it back up now because I think it does have some potential uses.
From my research, gas turbine engines start becoming less efficient under 400hp. I think engines under 400hp could be the opportunity for motorjets. It might be possible to build a motorjet for very cheap using commonly available engines and parts. From my understanding, these engines could be pretty efficient; much more than a gas turbine in that power range.
Where my design starts diverging from others, is that I'm trying to burn the leftover air fuel mixture that's coming out of the 2 stroke exhaust manifold. I used a 2 stroke leaf blower. I fabricated a pipe that goes from the leaf blower exhaust to the combustor. About halfway down that pipe, I put a fuel injector. The idea is that the fuel must would vaporize in the hot exhaust where it couldn't really burn due to lack of oxygen until it reaches the combustor where it mixes with fresh air from the Leaf blower and then ignites and provides thrust. I also added a hookup for propane to spray right before the combustor to aid in starting. I welded a nut on the combustor that a sparkplug screws into. The combustor is 2" black pipe with a 1.5" reducer at the end.
I can get ignition but it blows out when I try to rev up the Leaf blower. I haven't done any calculations to determine what size pipe the combustor should be, how much of a reducer if any; I was just shooting from the hip seeing if it would work. I'm thinking about removing the reducer, adding a gasoline vaporizer, possibly bypassing using the 2 stroke exhaust. Maybe its not getting enough oxygen with the 2 stroke exhaust? I figured the amount of exhaust compared to the amount of fresh intake air is minuscule, but maybe not?
I'd really like to capture and use that air fuel mixture because that's one of the things that would make this engine so efficient. I've actually been trying to design and build better 2 stroke engines for a decade now because they're so great for aviation (small aircraft). About 30% of your fuel is going out the exhaust on a 2 stroke engine without an expansion pipe, making use if that could save a lot of fuel. The power to weight ratio of 2 strokes is high, very simple, that's why I love them.
I'll add more tomorrow, its getting late! One last thing, there's tons of videos of people making motorjets from electric Leaf blowers which is also really cool; but I think my version would be cooler and actually be capable of lifting a plane off the ground for hours.
I'm going to try posting a few links of videos and pictures below:
drive.google.com/file/d/1xZtLQnqXCiBAbjKI4JjwqnAigm5c2GZT/view?usp=drivesdk
drive.google.com/file/d/1KabsjuNXyOH-8spFiy_Nqb_yGwKYXm7V/view?usp=drivesdk
www.facebook.com/jordan.brandt.33/videos/10225078206890321/
It's been so long since I've been on here I couldn't remember my username and had to make a new one! Anyways, just wanted to share a little about a project I've been working on but haven't touched in nearly a year: the motorjet.
Ever wanted a jet engine without all the hassle of high RPM parts? Well then, The Motorjet may be right for you! At the most basic level, a motorjet is a reciprocating piston engine attached to a compressor with an afterburner; very simple. You could also add a turbo to compensate at higher altitudes or even add an additional combustor so that the turbo could function as a gas generator.
Doing some research on this I found that motorjets were actually the first kind of jet engine to be flown. This was before we had good enough metallurgy to make turbine blades that could survive high heat, RPM and vibrations. Once that problem was solved, the motorjet fell to the wayside. I'm picking it back up now because I think it does have some potential uses.
From my research, gas turbine engines start becoming less efficient under 400hp. I think engines under 400hp could be the opportunity for motorjets. It might be possible to build a motorjet for very cheap using commonly available engines and parts. From my understanding, these engines could be pretty efficient; much more than a gas turbine in that power range.
Where my design starts diverging from others, is that I'm trying to burn the leftover air fuel mixture that's coming out of the 2 stroke exhaust manifold. I used a 2 stroke leaf blower. I fabricated a pipe that goes from the leaf blower exhaust to the combustor. About halfway down that pipe, I put a fuel injector. The idea is that the fuel must would vaporize in the hot exhaust where it couldn't really burn due to lack of oxygen until it reaches the combustor where it mixes with fresh air from the Leaf blower and then ignites and provides thrust. I also added a hookup for propane to spray right before the combustor to aid in starting. I welded a nut on the combustor that a sparkplug screws into. The combustor is 2" black pipe with a 1.5" reducer at the end.
I can get ignition but it blows out when I try to rev up the Leaf blower. I haven't done any calculations to determine what size pipe the combustor should be, how much of a reducer if any; I was just shooting from the hip seeing if it would work. I'm thinking about removing the reducer, adding a gasoline vaporizer, possibly bypassing using the 2 stroke exhaust. Maybe its not getting enough oxygen with the 2 stroke exhaust? I figured the amount of exhaust compared to the amount of fresh intake air is minuscule, but maybe not?
I'd really like to capture and use that air fuel mixture because that's one of the things that would make this engine so efficient. I've actually been trying to design and build better 2 stroke engines for a decade now because they're so great for aviation (small aircraft). About 30% of your fuel is going out the exhaust on a 2 stroke engine without an expansion pipe, making use if that could save a lot of fuel. The power to weight ratio of 2 strokes is high, very simple, that's why I love them.
I'll add more tomorrow, its getting late! One last thing, there's tons of videos of people making motorjets from electric Leaf blowers which is also really cool; but I think my version would be cooler and actually be capable of lifting a plane off the ground for hours.
I'm going to try posting a few links of videos and pictures below:
drive.google.com/file/d/1xZtLQnqXCiBAbjKI4JjwqnAigm5c2GZT/view?usp=drivesdk
drive.google.com/file/d/1KabsjuNXyOH-8spFiy_Nqb_yGwKYXm7V/view?usp=drivesdk
www.facebook.com/jordan.brandt.33/videos/10225078206890321/
