Twin Rod Avadi Engine - Perfect Balance in a Single Cylinder - Genius or Just Another Pipedream?
402,391
Published 2024-05-19
Patreon: www.patreon.com/d4a
Become a member: youtube.com/channel/UCwosUnVH6AINmxtqkNJ3Fbg/join
Motivation: / @grit00000
It's time to review another novel engine design and today we are going top inspect the Avadi MA 250 engine. As always I’ll explain what makes it special, how it works, the strengths and weaknesses of the design as well as the potential for it to enter mass production.
So as you can see this is a rotary engine, but it’s not rotary in the way that a Wankel/Mazda rotary engine is. This is still piston based with the big difference between this and conventional engines being that here the entire cylinder rotates within a casing and we have two connecting rods and two crankshafts for one piston. The crankshafts are geared to a stationary ring gear.
When I saw this engine for the first time the first thing that came to my mind was “hey this a big gyroscope. The cylinder spins in this direction, the crankshafts spin within it, kind of like a gyroscope. Ok that’s interesting….but why? There is no inherent benefit to making an engine cylinder together with the piston rotate around an axis so why do it?
To understand why we must observe how is the cylinder spinning. The spinning is done via gears. Why gears? If you want to make something spin there are more efficient ways than gears.
If we look at the Avadi website we will see they claim that the gears provide a reduction or torque increase for the engine. And yes this is of course true. All geared transmissions work on the same principle.
If we take two gears. A small input gear and an output gear that is twice the size we will double our torque output. This is the same arrangement as in the Avadi engine the pinion gears on the crankshaft are half the size or half the number of teeth of the fixed ring gear. So if we imagine that have an input speed of 1000 rpm and 10 Nm of torque at the small gear than our output speed at the large gear will be 500 rpm and the output torque will be 20Nm. A gear that is twice as large halves speed and doubles torque. This happens because the larger gear has a greater circumference and therefore the distance from the teeth to the center is doubled. When we double this distance we double the leverage and thus the torque. The speed is halved because for every two revolutions of the small gear the large gear makes only one revolution, so we have a 2:1 gear ratio.
So yes, the geared arrangement does increase torque as Avadi claims but this is NOT the reason why they implemented this solution. If they were interested only in torque then they could have done a 4:1 gear ratio and quadrupled the torque. So why 2:1? Think about it, what else has a 2:1 gear ratio, what else rotates twice for ever 1 rotation of the other things?
Yes, that’s right! The crankshaft and camshaft in a conventional four stroke engine have a 2:1 ratio. The crankshaft rotates twice for every single rotation of the camshaft. Why?
Because a four stroke engine needs 720 degrees to complete a full combustion cycle. Intake, compression, combustion and exhaust - each stroke is 180 degrees of crankshaft rotation and 4 x 180 equals 720. But during those 720 degrees you want to open the intake valve only once and you want to open the exhaust valve only once. You want the intake valve open only during the intake stroke and the exhaust valve open only during the exhaust stroke. To achieve that all you need is a 2:1 rotation ratio between the crankshaft and the camshaft. A 2:1 ratio means that 180 degrees of crankshaft rotation is only 90 degrees of camshaft rotation. So all you have to do is place your camshaft lobe in the correct position in relation to the crankshaft and the piston and your intake valve will be open only when you want it to be open.
Now if we go back to the Avadi engine we will see that this engine has no camshafts, no valves, no springs no nothing but the four stroke rules still apply, with or without a camshaft. The Avadi engine has an incredibly simple valve train that essentially consists of only three holes. This is one of the main reasons why the engine is so compact and so light.
A special thank you to my patrons:
Daniel
Pepe
Brian Alvarez
Peter Della Flora
Dave Westwood
Joe C
Zwoa Meda Beda
Toma Marini
Cole Philips
#d4a #enginebalance
00:00 How it Works
10:54 Engine Balance
17:17 Breathing Issues
22:67 Drones
All Comments (21)
-
Support the channel by shopping through this link: amzn.to/3RIqU0u Patreon: www.patreon.com/d4a Become a member: youtube.com/channel/UCwosUnVH6AINmxtqkNJ3Fbg/join Motivation: www.youtube.com/channel/UCt3YSIPcvJsYbwGCDLNiIKA
-
When A Rotary engine and a "normal" Engine love each other alot, the do a special dance and the make this:
-
It's revolutionary because it revolves.
-
This is seriously one of the most educational channels on youtube
-
The ICE is truly an amazing feat of engineering. Well over 100 years already and no one’s been able to truly “re invent the wheel” and make a better basic design.
-
"All you have to do is position your holes accordingly, and get them to match at the correct time for the correct stroke." ... Engineering is beautiful. Context is king.
-
Low rpm and high torque is what you need for driving a propeller, and the cilindrical shape with axial output sounds very easy to package in a drone
-
Dude, this is the single best video of yours I have watched, your ability to explain complex mechanical principles is FAR better than ANY of my college professors. Also, the Avanti actually, genuinely looks like a good design.
-
The way you enter and explain the topic of your videos is phenomenal. You introduce it as advertised, make it seem like he best thing in the world, then proceed to explain how it is false and the reason why it is as advertised. then you explain the pros and cons. Absolutely amazing. Keep up the work my man.👍
-
The whole time I was thinking "I wish I had these for my rc planes" didn't think that's what it's pretty much for.
-
Finally a tourbillon engine. Complicated enough for a watch but made for an engine....or maybe not.
-
I work with a lot of machinery, and one important design flaw is the axial offset between the connecting rods on the wrist pin. When you offset, axially, two opposing forces, you get an inherent twisting action on the arms and a bending force on the pin unless there is a balancing force present. This increases stress concentrations at the corners of the bearing surfaces, increasing the probability of uneven wear. This is only worsened by speed and load. Even on components that sees fewer than ten movement cycles per day, this concentrated load quickly forces lubricants out of the critical areas and results in wiping of bushings, or localized deformation of bearing races. These things would tear themselves apart just from that alone.
-
The last four minutes of this video deserve a longer followup, it was really interesting to see the engineering in its context.
-
I admire how you explain engine balance every time again and again
-
I would love to see a video about 2-stroke Detroit Diesel engines. I think they could fit well in this series, even though the concept is old. Also, keep up the great work with these videos. Your content is realistic, unlike others that are more like fairy tales.
-
The most important part of the video is the last 2 minutes. It's beneficial because we can learn something.
-
Nice that you could find this lost footage. It is always a bonus when you can see how far you have come and what you learned along the way. Growing up on a small lake, I always wanted a sailboat. I did have a small inflatable one, but usually had row boats I took German in High School 89-92 and graduated in 1993. My teacher Frau Ferris was so happy when the Berlin Wall came down in '89. She taught 6 classes of French, but really spoiled her German classes.
-
21:54 but: -you can make this hole oval or triangle to make surface bigger, you can even extend it to the side wall of the cylinder - there is no obstructions(open valve) in the way - you are not limited by valve lift and potential collision valve and piston, it can be open longer.
-
The Motors inherent balance would be an advantage for ultra lights and para gliders. The propeller speed reduction unit being an integral part of the motor would also be advantageous and reduces weight. It also might have the potential of improved fuel efficiency, while being more reliable than two strokes. Those last two points would be debatable, have to wait and see.
-
Many of your videos are pretty accurate, but this is another one that I have some issues with. The biggest issues I have is at around 19:30 when you are explaining that the output at the crankshaft is not the output at the crankshaft because the engine uses gears for timing instead of gears and a chain for timing. This engine will have a power stroke every revolution on the crankshaft vs a conventional single piston engine having a power stroke every two rotations of the crankshaft, however, the power stroke for this engine will only be effective for about 90° of rotation vs a conventional single piston engine at about 180 degrees of rotation. This engine will fire twice in 720° of rotation on the crankshaft for about 180 degrees of power output every 720° of rotation making the comparison between the two engines very similar.
