Engine technology, how far have we come
08-03-2006, 08:24 PM
#1
Engine technology, how far have we come
This question is for guys that have been flying high performance GS models for at least 20 years. Im thinking we have made little progress in performance since someone cut out a Sachs chainsaw and adapted a C&H with TCSA.
08-03-2006, 08:41 PM
#2
Senior Member
My Feedback: (1)
RE: Engine technology, how far have we come
We're still pumping a gas-air mix into a compressor and tossing an ignition source at it to make it explode, so I kinda have to agree with you. Our automobiles are doing the same thing, though. On the other hand, the turbine guys....
08-03-2006, 09:34 PM
#3
My Feedback: (50)
Join Date: Feb 2002
Location: Pasadena,
CA
Posts: 2,097
Likes: 0
Received 0 Likes
on
0 Posts
RE: Engine technology, how far have we come
In regards to the engines, there have been advances. Off the shelf commercial 2-stroke cylinders are generally made in the hundreds of thousands, their power band is above what we need, a few extra ounces is not of importance compared to reliabality and cost.
Looking at our purpose built 2-stroke gas engines, we now have a very light, efficient and user friendly electronic ignition on these engines. We have a better power to weight ratio (also due to improved building techniques) than earlier. We have to a large extent more user friendly engines.
The jet guys pay 2-4 times more for their engines than we do. If you are willing to pay the same for a combustion engine I am sure you can have a nice engine made for you. An engine is just a pump, since we're limited by the speed of our propellers, we can't really get a 2-stroke engine to make more power per volume, than they are now. If you put a 2:1 reduction gear in the nose, you could probably make twice the HP, but needing much better cooling and using much more fuel.
DKjens
Looking at our purpose built 2-stroke gas engines, we now have a very light, efficient and user friendly electronic ignition on these engines. We have a better power to weight ratio (also due to improved building techniques) than earlier. We have to a large extent more user friendly engines.
The jet guys pay 2-4 times more for their engines than we do. If you are willing to pay the same for a combustion engine I am sure you can have a nice engine made for you. An engine is just a pump, since we're limited by the speed of our propellers, we can't really get a 2-stroke engine to make more power per volume, than they are now. If you put a 2:1 reduction gear in the nose, you could probably make twice the HP, but needing much better cooling and using much more fuel.
DKjens
08-03-2006, 09:52 PM
#4
RE: Engine technology, how far have we come
I'd like to see a more affordable and lighter reduction gear than the current model offered by Mick Reeves. He makes a 1.75:1 reduction system for the Zenoah G-62, but it weighs 2 pounds and costs $300.
I wish I had the mill, lathe and knowledge to build a lighter system for the Zenoah engines. I'd build it to run the engine at 8000-9000RPM and turn a big fat prop around 5000-5500RPM.
I know it would use more fuel, but gasoline and oil is so much cheaper than glow fuel already. It's not a real big concern to me. If I have to replace my 18oz tank with a 24oz tank--thats not that big of a deal. It's only a couple ounces on a plane that most likely weighs 15--20 pounds anyway, and 6oz of extra gas per flight isn't going to burn a hole in my wallet. I can baffle it and put some cooling ducts in to cool it. Not to worried about that either.
I agree with all of DKJens points about fuel consumption and heat. I just wouldn't let it stop me from installing a reduction system if it would let me turn a more scale prop at lower RPM.
I agree that modern engines are quite a bit more technologically advanced than the chainsaws that were available 20yrs ago. I'm still using the 25yr old technology, because I run mostly conversion engines and Zenoah engines with electronic ignition. But, if it works, and it's cheaper--why fuss with something that costs twice as much? Toss in the fact that I'm poor, and I don't have much choice.
I wish I had the mill, lathe and knowledge to build a lighter system for the Zenoah engines. I'd build it to run the engine at 8000-9000RPM and turn a big fat prop around 5000-5500RPM.
I know it would use more fuel, but gasoline and oil is so much cheaper than glow fuel already. It's not a real big concern to me. If I have to replace my 18oz tank with a 24oz tank--thats not that big of a deal. It's only a couple ounces on a plane that most likely weighs 15--20 pounds anyway, and 6oz of extra gas per flight isn't going to burn a hole in my wallet. I can baffle it and put some cooling ducts in to cool it. Not to worried about that either.
I agree with all of DKJens points about fuel consumption and heat. I just wouldn't let it stop me from installing a reduction system if it would let me turn a more scale prop at lower RPM.
I agree that modern engines are quite a bit more technologically advanced than the chainsaws that were available 20yrs ago. I'm still using the 25yr old technology, because I run mostly conversion engines and Zenoah engines with electronic ignition. But, if it works, and it's cheaper--why fuss with something that costs twice as much? Toss in the fact that I'm poor, and I don't have much choice.
08-04-2006, 08:04 AM
#6
Senior Member
Join Date: Apr 2004
Location: Rock City, IL
Posts: 106
Likes: 0
Received 0 Likes
on
0 Posts
RE: Engine technology, how far have we come
I have not been in the sport for 20 years but I have 20 years experience with 2 strokes in other sports.
Model aircraft engines have not scratched the surface of existing technology as far as output per CC of displacement. Of course there are problems with achieving higher specific outputs,
weight and room for tuned pipes, more critical tuning, need for application specific, or tuneable,
pipes for each aircraft prop combination, liquid cooling for heat rejection of high specific output applications.
All of this for a market that is not a "gear head market". I do not think so.
Most people want to fly and are not into tuning for ultimate performance unless they are racing or
possibly pattern. Both of these are a relatively small portion of the sport.
Model aircraft engines have not scratched the surface of existing technology as far as output per CC of displacement. Of course there are problems with achieving higher specific outputs,
weight and room for tuned pipes, more critical tuning, need for application specific, or tuneable,
pipes for each aircraft prop combination, liquid cooling for heat rejection of high specific output applications.
All of this for a market that is not a "gear head market". I do not think so.
Most people want to fly and are not into tuning for ultimate performance unless they are racing or
possibly pattern. Both of these are a relatively small portion of the sport.
08-07-2006, 07:25 AM
#7
Senior Member
Join Date: Mar 2002
Location: Kingston,
ON, CANADA
Posts: 4,925
Likes: 0
Received 3 Likes
on
3 Posts
RE: Engine technology, how far have we come
Can't figure out why they havn't built a 4 stroke with the PTO off the camshaft instead of the crankshaft. Built in 2 to 1 reduction.
