2 stroke alternative ?

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EzyBuildWing

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Joined
Sep 23, 2009
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56
Location
Sydney NSW Australia
Electric looks like the way to go guys....check out these 3 vids .....

700 hp electric Beaver amphibian....first flight just a few days ago.


Twin-engined electric trike...swooping and soaring....


ditto.

A recent Kitplane article showed a homebuilt Strojenic S2 motor-glider powered with a Zero Electric-Motorcycle motor-battery combo! Maybe an electric single-seat Breezy(Zero motor) would be neat for 40-minute flights, and pretty inexpensive.

 

henryk

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Joined
Mar 8, 2010
Messages
5,213
Location
krakow,poland
Electric looks like the way to go guys....check out these 3 vids .....

700 hp electric Beaver amphibian....first flight just a few days ago.


Twin-engined electric trike...swooping and soaring....


ditto.

A recent Kitplane article showed a homebuilt Strojenic S2 motor-glider powered with a Zero Electric-Motorcycle motor-battery combo! Maybe an electric single-seat Breezy(Zero motor) would be neat for 40-minute flights, and pretty inexpensive.
https://www.dropbox.com/s/htftd6ttj1b2emj/Dym.mp4?dl=0

=differential conterrotating drived propellers =+30 % ! (235/180 kG )
 

Yellowhammer

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Joined
Feb 21, 2020
Messages
107
If someone could do some research on the Rotax 800 and 900 4 stroke engines, and make them work for an aircraft, then we would all be in better shape!
 

MadProfessor8138

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Nov 3, 2015
Messages
830
Location
Ekron,Kentucky
Yellowhammer.......be it Rotax,Yamaha,Cuyuna,Kawasaki,B&S,etc....the engine itself is almost never the issue unless it is being operated as a direct drive.
When you operate an engine as direct drive then that engine needs to be designed for that scenario from the very beginning.
For the most part,run any engine within its designed rpm & heat range and the engine will care less if it's on a motorcycle,snowmobile,mower,car,generator,etc.
There are so many engines out there that would make awesome aircraft engines....but there are no redrives available for those particular engines.
I'm not familiar with the Rotax 800 & 900 engines but I will Google them.
What are the redrive options for them ?
The Yamaha conversions are 4-stroke and are great engines.....but....a new Rotax box + adapter + engine + misc. = about $9-10k for an airworthy engine and redrive.

Engines are cheap and reliable.......the cost is the redrive.
Build a dependable redrive and offer it at a reasonable price.....then prices for aircraft power will come down.

Kevin
 

MadProfessor8138

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Log Member
Joined
Nov 3, 2015
Messages
830
Location
Ekron,Kentucky
I just googled the Rotax 800 & 900 engine.......very nice.
However,from what I saw in the pics,neither engine will accept a gearbox...strictly pulley redrive.
Maybe someone with machinist abilities could modify the case or design an adapter to allow gearbox use.....

Kevin
 

PMD

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Apr 11, 2015
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236
Location
Martensville SK

Armilite

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Joined
Sep 5, 2011
Messages
3,270
Location
AMES, IA USA
Yellowhammer.......be it Rotax,Yamaha,Cuyuna,Kawasaki,B&S,etc....the engine itself is almost never the issue unless it is being operated as a direct drive.
When you operate an engine as direct drive then that engine needs to be designed for that scenario from the very beginning.
For the most part,run any engine within its designed rpm & heat range and the engine will care less if it's on a motorcycle,snowmobile,mower,car,generator,etc.
There are so many engines out there that would make awesome aircraft engines....but there are no redrives available for those particular engines.
I'm not familiar with the Rotax 800 & 900 engines but I will Google them.
What are the redrive options for them ?
The Yamaha conversions are 4-stroke and are great engines.....but....a new Rotax box + adapter + engine + misc. = about $9-10k for an airworthy engine and redrive.

Engines are cheap and reliable.......the cost is the redrive.
Build a dependable redrive and offer it at a reasonable price.....then prices for aircraft power will come down.

Kevin
============================================

Don't lump all Engines into that Direct Drive issues. Only the 185UL had problems and that was addressed with bigger PTO Shaft. 2 Strokes aren't good performers at low rpm! They idle best at 2000rpm+, 4 Strokes can idle down to 600rpm+. Hirth makes a Direct Drive Hub for their Engines but very few People ever use them. Since 6500rpm is Industry Standard for 2 Strokes. A 503 rated 50hp@6500rpm with a 30mm 1:10 Taper turning a Max 37" x 14 (2) Blade Prop at 6500rpm makes Static Thrust of 212.31 lbs and needs 48.954 hp and it doesn't go Super Sonic. A 670 has a bigger PTO of 33mm 1:7.5 Taper! A 503UL with a 2.0 B Redrive 6500/2.0 = 3250rpm you can turn a larger Max 68" x 10 (2) Blade Prop and make Static Thrust of 605.53 lbs and needs 49.865 hp. That's WHY, most people don't use a 2 Stroke in Direct Drive.

Can you play with the Prop & HP Numbers to make something work, Yes, for some Applications. The 503UL is to Heavy for Part 103, but may work for some Small Kit Planes. That same 503UL could be Optimized for say Direct Drive Max 5000rpm. At 5000rpm turning a 48" x 10 (2) Blade Prop and make Static Thrust of 355.83 lbs and needs 45.080 hp. A 48" x 9 (2) Blade Prop makes Static Thrust of 355.83 lbs and needs 40.572 hp. A Stock 503UL makes 32.9hp@5000rpm. Just adding a Tuned Piped Designed for 5000rpm, 32.9 + 22% = 40.1hp, 32.9 + 38% = 35.4hp.

For Part 103 a Direct Drive 277 would be desirable. The 277UL Fan Motor is 65lbs with B Drive & Exhaust. The 277UL Free Air is lighter. In Direct Drive you loose about 9.4 lbs for Gear Drive also. It actually Dynoed by R&D Aero at 25.4hp@6000rpm! At 6000rpm in Direct Drive mode a 40" x 6 (2) Blade Prop makes Static Thrust of 247.10 lbs and needs 22.540 hp. A 40" x 7 (2) Blade Prop makes Static Thrust of 247.10 lbs and needs 26.696 hp. 26.696 - 25.4 = 1.296 hp you have to find! A Better Less Restrictive Muffler would probably do that. Some mild Porting would also work.

ULTRALIGHT NEWS PROP RECOMMENDATIONS for 277UL. 6250rpm/2.0 = 3125rpm
44 x 34 at 3125rpm makes Static Thrust of 98.14 lbs and needs 26.421 hp.
http://godolloairport.hu/calc/strc_eng/index.htm

ROTAX PROPS ULTRALIGHT NEWS.jpg
 
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