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Will the TD .09 stock needle valve work on bladder? Cox_ba12




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Will the TD .09 stock needle valve work on bladder? Empty Will the TD .09 stock needle valve work on bladder?

Post  Ken Cook Fri Jun 01, 2012 6:23 pm

I built this particular plane about 3 years ago. It sat due to severe CG problems. The majority of planes are all going to be leaning towards nose heavy which isn't a real bad problem. When you have a tail heavy plane, it almost takes 2x the weight to get the CG back. The other problem is cosmetically it's difficult to hide it. Here is the plane and the plans can be downloaded free http://www.hippocketaeronautics.com/cl_sp_white_lightening.htm . I've had great success using flat winged planes like the Sig Skyray. The Skyray flies beautifully with a Black Widow.

Here is where the problem arose for me, during the build I felt the stab on this plane was extremely large. This is a good thing for a stunter but my concerns were in the weight dept. Even though I chose and weighed all my wood prior to building I have a plane in front of me now in paint minus clear that weighs 3.87 oz's. This is a good weight except the majority of it is behind the CG. The wing tapers on this plane's leading and trailing edge. The center chord is 7" while the tips are 5 1/4". This has a fairly large slab of wing at 28".

I recently contacted the designer in which he insisted on in his several years of developing this plane that I shouldn't relocate the wing to correct the CG. He said these are tried and true tested numbers and therefore any additional weight needed will have little affect on the performance due to the large amount of wing.

If I use the TD .049, the plane will take at least another 1 3/4 oz's to balance at the plans CG. The TD .09 already is that approximate weight. If I use a bladder, I could eliminate the weight of a tank and just have a cardboard tube . I really have little experience with the .09 as it just wasn't popular in the control line end. Very few designs use the .09. This plane just looks like its size demands the TD .09 as it just looks correct in the nose and the .049 looks like tiny up front. I just wondered if the needle would work on a pressure bladder. I know the .049's work far superior using the finer threaded needles. Any help would be appreciated. Ken
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Post  RknRusty Fri Jun 01, 2012 8:37 pm

I don't know for sure, Ken, but just for the sake of guesstimating, the fine threads on the .049 needle are 128 tpi. I think the standard NV is 80 tpi, so it's a pretty big difference on the small engines.

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Post  Cribbs74 Fri Jun 01, 2012 11:51 pm

shawn cook wrote: I built this particular plane about 3 years ago. It sat due to severe CG problems. The majority of planes are all going to be leaning towards nose heavy which isn't a real bad problem. When you have a tail heavy plane, it almost takes 2x the weight to get the CG back. The other problem is cosmetically it's difficult to hide it. Here is the plane and the plans can be downloaded free http://www.hippocketaeronautics.com/cl_sp_white_lightening.htm . I've had great success using flat winged planes like the Sig Skyray. The Skyray flies beautifully with a Black Widow.

Here is where the problem arose for me, during the build I felt the stab on this plane was extremely large. This is a good thing for a stunter but my concerns were in the weight dept. Even though I chose and weighed all my wood prior to building I have a plane in front of me now in paint minus clear that weighs 3.87 oz's. This is a good weight except the majority of it is behind the CG. The wing tapers on this plane's leading and trailing edge. The center chord is 7" while the tips are 5 1/4". This has a fairly large slab of wing at 28".

I recently contacted the designer in which he insisted on in his several years of developing this plane that I shouldn't relocate the wing to correct the CG. He said these are tried and true tested numbers and therefore any additional weight needed will have little affect on the performance due to the large amount of wing.

If I use the TD .049, the plane will take at least another 1 3/4 oz's to balance at the plans CG. The TD .09 already is that approximate weight. If I use a bladder, I could eliminate the weight of a tank and just have a cardboard tube . I really have little experience with the .09 as it just wasn't popular in the control line end. Very few designs use the .09. This plane just looks like its size demands the TD .09 as it just looks correct in the nose and the .049 looks like tiny up front. I just wondered if the needle would work on a pressure bladder. I know the .049's work far superior using the finer threaded needles. Any help would be appreciated. Ken

The TD .09 has a fine thread NVB and I see no reason it wouldn't work. Not as fine as a KK NV though. The power of the .09 is substantial and it may be a lot to handle in something designed for an .049-.061
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Post  Ken Cook Sat Jun 02, 2012 12:16 am

Thanks for the reply Ron, I did give the power some thought. I figured an additional head gasket or two would tame things down a bit. I could always go out on the line length a bit more. My dad purchased the engine in the late 60's and I only witnessed it in use one time. Other than that, the engine has been sitting in a box. Ken
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Post  Ken Cook Sat Jun 02, 2012 1:58 am

Rusty, I was afraid of the threads not being fine enough. I will try it on a test stand first. The next step would be to make a remote needle valve. This would then require a different fuel delivery system into the engine. I'm undecided once again. Ken
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