"1/2 A" & "1/8 A" airplanes These are the small ones...more popular now than ever.

COX REMOTE NEEDLE VALVE

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Old 12-28-2011, 10:22 PM
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combatpigg
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Default COX REMOTE NEEDLE VALVE

I've got quite a collection of stock TD .049 needles that never got used and for years I've scratched my head as to how I could ever get some use out of them.

I'm working on a project where a tiny remote needle is needed. I took some aluminum round stock and machined it down to a press fit into the Cox needle body. I left a short nub sticking out in back so it could get mounted to a firewall or engine mount. The aluminum piece is cross drilled to line up with the discharge hole in the Cox unit.

We'll see later how well it works to feed a Norvel .074.
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Old 12-28-2011, 10:52 PM
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rcguy59
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Default RE: COX REMOTE NEEDLE VALVE

OK, I'll bite. Why would one need/want a remote needle on a Norvel. Not being a wiseass here, I'm just stumped. I have 9 of those little gems so I'm curious.
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Old 12-28-2011, 11:30 PM
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Jaspur_x
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Default RE: COX REMOTE NEEDLE VALVE

A cowled engine maybe, or fingers that get into spinning props. I dunno, I never even started my norvel 074 yet, just sits there waiting for my other engines to wear out,but that will take years considering I rarely fly anything that large anymore.

Great work CP , I had thought about modifying a in line fuel filter for same purpose
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Old 12-29-2011, 12:22 AM
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combatpigg
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Default RE: COX REMOTE NEEDLE VALVE

Thanks.
I'm working with a cowl and the stock carb is too big so I'm going to the trouble to make a venturi.
After considering the options, I wanted to make a fairly shallow notch in the cowl back by the firewall and I'll end up being able to leave both the muffler and needle alone if the cowl needs to come off.
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Old 12-29-2011, 12:29 AM
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Default RE: COX REMOTE NEEDLE VALVE

That makes sense. Is there more power to be had from the .074 with a venturi, without resorting to bladder pressure?
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Old 12-29-2011, 07:15 AM
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Default RE: COX REMOTE NEEDLE VALVE

I goofed around years ago with a .074 on bladder and speed props. By just removing the carb and sticking a tiny NVA into the holes in the case that secure the carb. I don't recall what the outcome was....I didn't touch the engine internally so the engine was limited. I don't know of anyone who has made one of these engines into a "AME .074".
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Old 12-29-2011, 08:47 AM
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Default RE: COX REMOTE NEEDLE VALVE

Looks like a nice solution, any pictures of the plane and cowl?

I have a cowled, and inverted, .074 in a super chipmunk. The carb and needle fitted quite easily, but the stock muffler was sticking out too much.

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Old 12-29-2011, 04:15 PM
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Default RE: COX REMOTE NEEDLE VALVE

That's a good looking plane Mr Cox..! [:-]

Here is the NVA pressed into a seperate hunk of aluminum that is held by 2 screws to the firewall.

The Venturi took almost 2 hours to make with that oval shaped section that inserts into the crankcase....so I'll be happy to make these for about $80 each............

The plane is based on a Mike Pratt design called The Force...but scaled way down and with a built up fuselage instead of a profile. It will be flown on 50 foot lines....I hope successfully.
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Old 12-29-2011, 04:28 PM
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Default RE: COX REMOTE NEEDLE VALVE

De Plane...!!
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Old 12-29-2011, 04:46 PM
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Default RE: COX REMOTE NEEDLE VALVE

looks like it will work to me,, good idea
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Old 12-30-2011, 02:14 AM
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Default RE: COX REMOTE NEEDLE VALVE

Nice lines on that plane, looks fast...

I was worried about overheating inside a cowl but the large fins seem very effective, I just put some baffles to direct the flow over the fins and made a large exit hole for the air. I love the handling of the .074 engine, but haven't pushed mine for high rpms, about 17500rpm on an APC6.3x4 and 10% Nitro is fine with me.

I tried to make a little movie of mine, it doesn't show that much but I love the direct throttling response from idle without hesitation. Just shows what can/could be done with small engines if the manufactures made a little effort.

Take off a little rich (engine cooled down while I fiddled with the camera), skip to about 1:10 where I lowered the idle;

[youtube]http://www.youtube.com/watch?v=trSCx-6zlAo&feature=mfu_in_order&list=UL[/youtube]
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Old 01-02-2012, 04:06 PM
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Jim Thomerson
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Default RE: COX REMOTE NEEDLE VALVE

I saw something similar to what you are doing. As a past Nats, I watched Doug Joyce (Joiner?) fly his canard clipper cargo airplane with two Cox TD 010's. He had a tank (bladder?) feeding a cox needle assembly like yours with line going to either of the TD 010's. As I recall he held the record at the time, and his system worked just fine. He is a free flighter who flys canards in various free flight events at a very high level of competition.
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Old 01-02-2012, 05:58 PM
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Default RE: COX REMOTE NEEDLE VALVE

Hi Jim...maybe that arrangement made his engines quit at the same time with more regularity..?
I have a twin engine RC biplane with a pair of TD .049s fed from the same bladder. There is a line that goes out of both ends of the same bladder to each NVA. The engines never do shutoff at the same time like you think they would....so most flights end up with a knife edge flight Grande Finale until both engines quit.
The magical thing about playing with model engine plumbing fittings is how well light press fits work, even with bladder pressure
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