Downline engine revs
10-29-2002 | 04:41 PM
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From: Rochester, NY
Downline engine revs
Here's a question / observation that I would like to bounce off the rest of the R/C commuity in hopes of confirming for finding an answer.
I have observed from sound and site that most fairly large planes running 2-stroke .60+engines tend to accelerate downline speed and engine RPM more than 4-strokes. Is this common knowledge and if so what causes it? Is it just that the 2 strokes due to the (2-stroke design) tend to spin-up easier when they encounter forced air via the downline? Additionally, it appears that glow 2-strokes are affected more than gas.
My comparison is genreally between ys.63 - ys 1.40 vs. moki 1.80 - 2.10. My statement about gas relates to my experience watching TOC in person.
What are you thoughts on the subject?
Mike
I have observed from sound and site that most fairly large planes running 2-stroke .60+engines tend to accelerate downline speed and engine RPM more than 4-strokes. Is this common knowledge and if so what causes it? Is it just that the 2 strokes due to the (2-stroke design) tend to spin-up easier when they encounter forced air via the downline? Additionally, it appears that glow 2-strokes are affected more than gas.
My comparison is genreally between ys.63 - ys 1.40 vs. moki 1.80 - 2.10. My statement about gas relates to my experience watching TOC in person.
What are you thoughts on the subject?
Mike
10-29-2002 | 07:07 PM
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Downline engine revs
Your observation is correct, for the most part. It is universal between all of the two-stroke and four-stroke engines that I have observed, whether glow or gas.
After riding two-stroke powered motorcycle street rockets for years, I bought a Honda four-stroke bike. On my very first ride, I left the driveway and went out onto a major highway. Down the road a piece was a nasty railroad track crossing. I was travelling at about fifty miles per hour when I rolled off of the throttle. Surprise! I darned near went over the handlebars! The compression of the four-stroke bike was very strong and very unexpected. Luckily, all turned out okay, but it scared the dickens out of me.
After riding two-stroke powered motorcycle street rockets for years, I bought a Honda four-stroke bike. On my very first ride, I left the driveway and went out onto a major highway. Down the road a piece was a nasty railroad track crossing. I was travelling at about fifty miles per hour when I rolled off of the throttle. Surprise! I darned near went over the handlebars! The compression of the four-stroke bike was very strong and very unexpected. Luckily, all turned out okay, but it scared the dickens out of me.
10-29-2002 | 09:40 PM
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Downline engine revs
I BELEIVE YOUR ARE CORRECT ABOUT THE 2 STROKE PICKING UP
SPEED DUE TO THE 2 STROKE DESIGN. THE SAME TORQUE BENEFIT YOU RECEIVE FROM THE 4 STROKE WITH INSTANT THROTTLE REPONSE IS THE SAME TORQUE THAT GIVES YOU MORE BRAKING POWER AT IDLE ON DOWN LINES.
SPEED DUE TO THE 2 STROKE DESIGN. THE SAME TORQUE BENEFIT YOU RECEIVE FROM THE 4 STROKE WITH INSTANT THROTTLE REPONSE IS THE SAME TORQUE THAT GIVES YOU MORE BRAKING POWER AT IDLE ON DOWN LINES.
10-29-2002 | 10:40 PM
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From: Rochester, NY
Downline engine revs
Appreciate your replies and thoughts.
I guess one think that puzzles me and seems to be contrary to the compression source, is that between my two engines, moki 1.8 and ys 1.4. Is that when flipping the props by hand it appears that the moki has much more compression than the ys1.4. Not to mention the compression on the moki 2.1 which took a finger nail off of one of my fingers, ouch! But the moki 2.1 will seems to rev right up when pointed down.
Could it be that when travelling on a downline the two stroke prop only needs to spin one revolution before it hits compression and fires vs. the four stroke has to spin two turns?
I know this may not be a big issue but it kind of drives me nuts because I'm not sure of the answer. Not to mention I'd like to slow my moki's down a bit when pointed down.
Take care.
Mike
I guess one think that puzzles me and seems to be contrary to the compression source, is that between my two engines, moki 1.8 and ys 1.4. Is that when flipping the props by hand it appears that the moki has much more compression than the ys1.4. Not to mention the compression on the moki 2.1 which took a finger nail off of one of my fingers, ouch! But the moki 2.1 will seems to rev right up when pointed down.
Could it be that when travelling on a downline the two stroke prop only needs to spin one revolution before it hits compression and fires vs. the four stroke has to spin two turns?
I know this may not be a big issue but it kind of drives me nuts because I'm not sure of the answer. Not to mention I'd like to slow my moki's down a bit when pointed down.
Take care.
Mike
