Search: Posts Made By: seanychen
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Forum: Glow Engines 09-21-2007, 06:33 PM
Replies: 12
Views: 1,400
Posted By seanychen
RE: Can I use a Graupner 12.5x7 - 3 blade on a YS63?

My Saito 100 swings the Graupner 12.5 x 7 3-blade at 10200 rpm peak, the same rpm it swings MA 14x7 prop. So this prop is definitely too big for YS 63.

Graupner's 11x7 3-blade is perfect load...
Forum: Glow Engines 09-03-2007, 10:15 PM
Replies: 95
Views: 6,397
Posted By seanychen
RE: 1 horsepower, really the power of a horse?

I think 1 pony can lift 50 kg 1 meter high in 1 second.

I can probably make it with leg press. Does that make me a pony?:D
Forum: Glow Engines 07-15-2007, 09:40 PM
Replies: 48
Views: 4,010
Posted By seanychen
RE: saito's 220 large bore carb & pump

I tested the Master Airscrew Classic 20x6 today. It seems to peak at about 8000 rpm, with the main needle at 2 turns out from fully closed. The engine seems to be real happy with this prop, as...
Forum: Glow Engines 07-13-2007, 10:14 PM
Replies: 48
Views: 4,010
Posted By seanychen
RE: saito's 220 large bore carb & pump

I recall my APC 19x8W peaking at 8000 rpm.
Forum: Glow Engines 07-13-2007, 10:12 PM
Replies: 48
Views: 4,010
Posted By seanychen
RE: saito's 220 large bore carb & pump

Not here:D

Some of us started diverging the main subject of carb design.:)
Forum: Glow Engines 07-13-2007, 07:00 AM
Replies: 48
Views: 4,010
Posted By seanychen
RE: saito's 220 large bore carb & pump

I think the title of this thread speaks of the bore on the carb, not the bore of the piston.
Forum: Glow Engines 07-12-2007, 09:07 PM
Replies: 48
Views: 4,010
Posted By seanychen
RE: saito's 220 large bore carb & pump

Just to clarify, I was referring to the volume of air-fuel mixture above the piston when the piston is at the Top Dead Center. The combustion volume is merely the little volume that's trapped between...
Forum: Glow Engines 07-12-2007, 08:55 PM
Replies: 48
Views: 4,010
Posted By seanychen
RE: saito's 220 large bore carb & pump

I am by no means an engine expert, and I wish not to hijack the Saito 220 thread to discuss the fuel economy of over-bored engines. I just know that my Saito 220 lasts longer than my Saito 180 on the...
Forum: Glow Engines 07-10-2007, 11:39 PM
Replies: 48
Views: 4,010
Posted By seanychen
RE: saito's 220 large bore carb & pump

I find the Biela 20x6 load to be on the high side for my Saito 220. It is much more comfortable with APC 19x8W than Biela 20x6. Maybe I should try a lesser load 20x6.
Forum: Glow Engines 07-10-2007, 11:35 PM
Replies: 48
Views: 4,010
Posted By seanychen
RE: saito's 220 large bore carb & pump

Hello,

There is not really a well defined correlation between bore and fuel consumption. But larger bore means the cylinder can combust more amount of air-fuel mixture per cycle. When the piston...
Forum: Glow Engines 07-09-2007, 11:26 PM
Replies: 48
Views: 4,010
Posted By seanychen
RE: saito's 220 large bore carb & pump

Also an over-bored engine tends to consume more fuel than the long stroke engine of same displacement. A prime example is Saito 82 v.s. Saito 91. Saito 91 puts out more thrust than the 82 at lower...
Forum: Glow Engines 06-18-2007, 11:34 PM
Replies: 7
Views: 2,297
Posted By seanychen
OS 200 Surpass-FI

http://www.os-engines.co.jp/2007spring-summer/fs200sfi/index.htm

Translated via Babelfish:

A thread the world of the stunt where the flight which is not disordered is required. O.S. The...
Forum: Glow Engines 06-14-2007, 08:55 PM
Replies: 11
Views: 929
Posted By seanychen
RE: What prop

MA 3-blade props get pretty good RPM for their advertised size. However, I find that the pitch flattens. My plane with 14x7 3-blade @ 9500 rpm flies at below 50 mph top speed. Theoretically it should...
Forum: Aerodynamics 04-30-2007, 08:44 PM
Replies: 20
Views: 2,782
Posted By seanychen
RE: Prop size vs Torque

Going from 2-blade to 3-blade requires 10% reduction of diameter to stay in the same rpm, assuming pitch, chord width and profile stays the same. Sometimes, chord width will be narrower (e.g. Master...
Forum: Glow Engines 04-30-2007, 08:31 PM
Replies: 29
Views: 4,834
Posted By seanychen
RE: Best prop for Magnum 61 four stroke in 6.5 lb warbird?

I think we should wait for his flight report before eagerly recommending expenditures, an imminent one however.
Forum: ARF or RTF 04-29-2007, 09:40 PM
Replies: 35
Views: 2,483
Posted By seanychen
RE: Just a matter of time. ARFs getting real cheap

You don't mean World Models, do you?
Forum: ARF or RTF 04-29-2007, 09:38 PM
Replies: 35
Views: 2,483
Posted By seanychen
RE: Just a matter of time. ARFs getting real cheap

Thanks the Brits for what they made Hong Kong into: hub of ARF trades!
Forum: Aerodynamics 04-29-2007, 09:35 PM
Replies: 20
Views: 2,782
Posted By seanychen
RE: Prop size vs Torque

Right thrust will help offset the left yaw during upward pitch. However, when you do an inverter pull-up (downward pitch), you will need left thrust.

Counter-rotating prop is perfect in theory,...
Forum: 3D Flying! 04-29-2007, 09:17 PM
Replies: 20
Views: 1,303
Posted By seanychen
RE: best 3D ARF under 400$

Extreme Flight Yak 74"
http://www.extremeflightrc.com/html/74yak54.html

QQ Yak 23%
http://www.somenzini.com/html/aircraft/yak73.html
Forum: Glow Engines 04-29-2007, 02:57 PM
Replies: 29
Views: 4,834
Posted By seanychen
RE: Best prop for Magnum 61 four stroke in 6.5 lb warbird?

Well, I wouldn't go to the extreme of 10x8 either, as it won't have enough prop wash to accelerate the plane to a speed that will take advantage of the 8" pitch.

What he really needs is a...
Forum: Glow Engines 04-29-2007, 12:24 AM
Replies: 29
Views: 4,834
Posted By seanychen
RE: Best prop for Magnum 61 four stroke in 6.5 lb warbird?

This estimation is more than just theory. This is an adjusted estimation based on my other "real" thrust measurements:

APC 13x4W @ 11000 rpm = 7.5 lb

Anyway, if the thrust is the same as...
Forum: Glow Engines 04-28-2007, 01:50 PM
Replies: 29
Views: 4,834
Posted By seanychen
RE: Best prop for Magnum 61 four stroke in 6.5 lb warbird?

OK Dave, this is not as straight forward as you think. Many factors affect the thrurst, including diameter, rpm, pitch, chord width, airfoil, and profile. From what I've gathered, I've found the...
Forum: Glow Engines 04-28-2007, 01:31 PM
Replies: 29
Views: 4,834
Posted By seanychen
RE: Best prop for Magnum 61 four stroke in 6.5 lb warbird?

Master Airscrew Classic 12.5x5. It will be the right load for the engine @ 10500 rpm, looks great, and fly scale speed at about 50 mph. For your Zero, you want the prop diameter to be large enough to...
Forum: ARF or RTF 04-25-2007, 09:49 PM
Replies: 8
Views: 1,598
Posted By seanychen
RE: Finished my Dave Patrick Ultimate!! update - maidened with video

My Ultimate setup:

For rudder I add the double bevel on the fin side, so max deflection will almost touch the elevator

For elevator I also double beveled, resulting in 60 deg of deflection...
Forum: Glow Engines 04-24-2007, 09:09 PM
Replies: 29
Views: 1,934
Posted By seanychen
RE: AX Engines

You shouldn't have to worry about an engine not lasting 10 gallons for your RV-4. Most RV-4s don't get that much flight time anyway. It's a sport plane, fly around type of plane. People who own RV4...
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