RE: Plastic Props

RE: Plastic Props
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RE: Plastic Props - 7/28/2004 2:06:51 AM

HighPlains

Posts: 2670
Joined: 3/2/2003
From: Over da rainbow, KS, USA
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Thanks for the reply Bob. My point was that there was a common starting point. If I remember right, the sleeve walls on the Jett and Nelson were thicker than the ST for holding shape better. Also, I seem to remember that the Nelson was using an OS back end for better breathing than the X-40 until he got his own parts made.

Nothing more than an air pump, that heats the air with a dash of fuel.

Thanks,
Bob

(in reply to bob27s)

Post #: 76

RE: Plastic Props - 7/28/2004 5:10:05 PM

John Z Williams Jr

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Joined: 9/17/2003
From: Boulder, CO, USA
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Ok, I have a question for you then, if the motor is at its root a air pump, would you say that fuel and air spitting out the front bearing is a loss in power because its a loss in air???? I have one motor that goes like stink, but it has a leak in the front end, it likes to spit fuel out the front bearing, could I or should I try and seal this loss in pressure???????
John W.

(in reply to HighPlains)

Post #: 77

RE: Plastic Props - 7/28/2004 5:16:02 PM

daven

Posts: 6914
Joined: 12/7/2001
From: Andover, MN, USA
Status: online

John,

Not sure why, but many of the faster engines I have seen all spit fuel out of the front bearing.

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(in reply to John Z Williams Jr)

Post #: 78

RE: Plastic Props - 7/28/2004 5:28:47 PM

HighPlains

Posts: 2670
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From: Over da rainbow, KS, USA
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Hey John,

Are you going to have another target aircraft at the next race? Hope we don't meet that way again, though it puts you into pretty good company as the list of people I have mid-aired is long and famous.

If you got an engine that goes like stink, I would not touch it. The amount of fuel that is leaking is most likely sealing any air leak and is really not a very large volume when compared to the amount of air going though the engine. I did have one that also ran well, but ran though 6 oz of fuel about a minute faster than other engines. I couldn't loan it out to friends getting started in 428 because it was a 9 lap setup for them. I could do 11 and change and still land with fuel.

They leak because they have lots of clearance in the crank to case and the front bearings aren't sealed. Your caller might not enjoy the shower, but hey, that's racing.

(in reply to John Z Williams Jr)

Post #: 79

RE: Plastic Props - 7/28/2004 6:47:29 PM

Jerry-B

Posts: 39
Joined: 1/29/2002
From: Ramsey, MN, USA
Status: offline

js3
How many scale models do you see with AMA numbers on there wings???

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Jerry-B

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Post #: 80

RE: Plastic Props - 7/28/2004 7:27:31 PM

js3

Posts: 1142
Joined: 1/30/2002
From: Arvada, CO, USA
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quote:

ORIGINAL: Jerry-B

js3
How many scale models do you see with AMA numbers on there wings???

Jerry,

I can't say that I've EVER seen a scale airplane with AMA numbers on its wings. But since when have scale airplanes had to abide by the PYLON RACING RULES?

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I feel a lot more like I do now than I did earlier!

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Post #: 81

RE: Plastic Props - 7/28/2004 8:08:23 PM

Ed Smith

Posts: 2837
Joined: 12/29/2001
From: Brantford, ON, CANADA
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Good one John, I like it!!

Ed S

(in reply to js3)

Post #: 82

RE: Plastic Props - 7/28/2004 8:36:06 PM

Ed Smith

Posts: 2837
Joined: 12/29/2001
From: Brantford, ON, CANADA
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quote:

I have one motor that goes like stink, but it has a leak in the front end, it likes to spit fuel out the front bearing, could I or should I try and seal this loss in pressure???????

No.

With the piston pumping away there is pressure to spare in the crankcase. This pressure pushes some fuel out through the front bearing. The front bearing is now getting good lubrication. As Martha would say "That is a good thing"!

Without accusing anybody of cheating I have known that crankcases have been honed out to increase the case to shaft clearance. The objective being to remove any chance of friction between the two. This would of course lead to fuel spitting out of the front when the engine is running. However some of my engines spit fuel out of the front and I am an honest man.

Ed S

(in reply to Ed Smith)

Post #: 83

RE: Plastic Props - 7/28/2004 10:30:33 PM

John Z Williams Jr

Posts: 121
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From: Boulder, CO, USA
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Oh yea I will have a good one for you to try and follow!!!! Just don't hit it this time.... I have heard A. Seaholm may come down for racing on the 14th.... I have all the new timings and compression ratings to try out.........

(in reply to HighPlains)

Post #: 84

RE: Plastic Props - 7/28/2004 10:35:39 PM

leeul

Posts: 61
Joined: 8/15/2002
From: Goodyear, AZ, USA
Status: offline

I have one engine that has a hole in the front bearing boss, is this stock? It is a 2nd hand engine.
and I wonder if any one else has seen this on ther engines. It spits lots of fuel.

Lee

I still am haveing problems posting pics. it is on the front of the bearing boss, behind the spinner and goes through into the carb hole.

< Message edited by leeul -- 7/28/2004 10:41:47 PM >

(in reply to Ed Smith)

Post #: 85

RE: Plastic Props - 7/28/2004 10:50:54 PM

splatt

Posts: 651
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From: splattsville, MN,
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the older Nelsons had a hole that you describe. I used a little JB weld and filled the hole. Still get gobbs of fuel out the front.

(in reply to leeul)

Post #: 86

RE: Plastic Props - 7/28/2004 11:04:44 PM

Ed Smith

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From: Brantford, ON, CANADA
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That is stock,

I seem to remember, some time ago. I was told it was to allow some of the leaking fuel to get sucked back into the engine. Whether true or not I cannot say.

Splatt,
Fuel could not come out of that hole. It led into the venturi entry so the flow was in the other direction.

Ed S

(in reply to leeul)

Post #: 87

RE: Plastic Props - 7/28/2004 11:08:53 PM

HighPlains

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From: Over da rainbow, KS, USA
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Oh, so that's how I can tell that all my Nelsons are old.

Henry put that hole there to attempt to draw the excess fuel back into the engine.

John,

I wasn't following you when we mid-air'ed. Following would imply that you were ahead. I think that the correct term is LAPPING. Didn't you think that the Thumper was well named? It made a BIG thump when it hit the ground.

Next time fix your own damn airplane.

(in reply to splatt)

Post #: 88

RE: Plastic Props - 7/29/2004 4:22:15 PM

SSAN

Posts: 440
Joined: 1/19/2002
From: Queen Creek, AZ, USA
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It look like we're getting of topic here regarding this debate about Plastic Props...
Lets get back to it and see what more people think. I'm for it since I will be moving toward Q40 next.

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(in reply to HighPlains)

Post #: 89

RE: Plastic Props - 7/29/2004 7:58:03 PM

StregaFlyer

Posts: 53
Joined: 7/28/2004
From: South Beloit, IL, USA
Status: offline

I think only one plastic prop is needed in Q40.. You can make good wood props, it's just like flying ya gotta PRACTICE PRACTICE PRACTICE... If we let APC open up on QM40 props you'll have to break 1 minute to win a heat.. Heck I remember 10 years ago we switched to the long course in Q500 cause people were going too "fast".. Now were on a course that is longer, and turning 1:05's with Q500's and 1:01's with QM40's.. What's the next idea to give the pilots more time to think on the course???

(in reply to SSAN)

Post #: 90