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RE: Thoughts on a homemade regulator

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RE: Thoughts on a homemade regulator

Post  rat9000 on Tue Dec 16, 2014 8:44 am

Roddie,I was curious where you were at on the regulator issue,I followed that thread closely and was intrigued with it, I've not tried a bladder but someday I will,still checking it out.In one of your posts you said mechanical pumps are driven by a cam to produce pressure on a given RPM,needing no regulator for carb. set ups,not so,mechanical pumps have internal bypass,to regulate press,as a rule we do not exceed over 5 pounds on needle and seat because of flooding at idle,at wide open throttle your looking for volume,aftermarket pumps move a lot of fuel but are still pressure sensitive.From what I've read bladders are tempermental ,I would like to see that thread keep going.rat
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Re: RE: Thoughts on a homemade regulator

Post  roddie on Tue Dec 16, 2014 2:20 pm

I haven't done any testing yet.. but I plan on running a bladder for the first time too, and very soon. I'd like to have at least 3 or 4 regulators of different sizes ready by then. I like the "capillary-tube" suggestion by CEF member "Phil" (pkrankow).. but it's likely that it's one size only... and I'd like more choices in ID size to experiment with.. because of the variables involved. Elevation, ambient temperature, fuel type, oil content/viscosity, engine condition, engine size, prop size... these are all factors that could influence how well a regulator will work. An unrestricted bladder is capable of supplying much more fuel "volume" than the engine would typically draw on a suction feed.. so why put all that pressure directly on the needle.. and expect it to cooperate?
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Re: RE: Thoughts on a homemade regulator

Post  JPvelo on Tue Dec 16, 2014 3:58 pm

See where the tubing size steps down at the filter? That's all the regulator you need for a bladder. No need to over complicate a simple system that works well.

Jim
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Re: RE: Thoughts on a homemade regulator

Post  roddie on Tue Dec 16, 2014 8:36 pm

JPvelo wrote:See where the tubing size steps down at the filter? That's all the regulator you need for a bladder. No need to over complicate a simple system that works well.

Jim

Is that a standard 80 tpi needle Jim?
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Re: RE: Thoughts on a homemade regulator

Post  JPvelo on Tue Dec 16, 2014 9:04 pm

No it's a fine thread. I've heard that "little red caps" will work as a bladder on standard needles but I've not tried them.

http://littleredcap.com
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Re: RE: Thoughts on a homemade regulator

Post  roddie on Tue Dec 16, 2014 9:34 pm

JPvelo wrote:No it's a fine thread. I've heard that "little red caps" will work as a bladder on standard needles but I've not tried them.

http://littleredcap.com

Jim, since this thread is an "RE:" to my original thread, I should re-state (in short) why I feel a regulator might be worth trying. Some people may NOT want to mod their engine for a fine-thread needle in order to run a bladder. The trouble with this.. from what I understand, is too much pressure. A standard needle is designed to meter fuel into the venturi with a suction feed.. and not to restrict fuel that's being "forced" through it. Does this make sense?
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Re: RE: Thoughts on a homemade regulator

Post  TDbandit on Tue Dec 16, 2014 10:22 pm

While on this subject, I got to thinking, a regulator would help the sensitivity issue that exists while using standard needles under pressure by reducing the amount of pressure getting to the needle however I feel you can still use a standard needle with full pressure as long as you change the ratio of the needle (larger than stock knob on the needle) which reduces the amount of movement on the needle per turn and remove any type of ratchet spring and go to a friction collar. The old YS.45FS twostroke used a built in pressure pump and regulator which controlled the amount of pressure going to the high speed needle and idle circuit plus a large dia needle valve knob and while tedious to setup initially, it did work well so I would think a regulator would help as long as you don't mind adding a little complexity, and if you don't, just don't move the needle as much. (Bandit)
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Re: RE: Thoughts on a homemade regulator

Post  Cribbs74 on Tue Dec 16, 2014 10:46 pm

Only one way to find out for sure...

I'd be interested in hearing if it works. This could be hashed out on a bench with a static run.

Sometimes the the labor outweighs the cost although I do understand what limited cash is like. Keep in mind hard tanks can work, but it takes a little trial and error. TD's are the biggest problem. I have never had a Medallion give me an issue on a hard tank. Horseshoe or Postage stamp Cox engines will work fine on a hard tank.

Bladders are very simple once you get the routine down. Rusty made it even simpler by showing me how to fill the bladder with a one way check valve.

Bladders give no nonsense runs (until it gets cold) and once you start getting into heavy stunting it's a real blessing.




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Re: RE: Thoughts on a homemade regulator

Post  roddie on Wed Dec 17, 2014 9:54 am

Cribbs74 wrote:Only one way to find out for sure...

I'd be interested in hearing if it works. This could be hashed out on a bench with a static run.


I'll confess.. I'm guilty of not following through with "proof of concept" for some of the ideas I've pitched here since being a forum member. Everyone likes to see results. I guess that sometimes I'm hoping that one of you might try one of them for yourself and report on your findings. I need to apologize.. because this is frustrating to those of you who are following a thread with interest.. only to be left hanging on whether the topic of discussion actually works. I'll try to be more mindful of this moving forward.
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Re: RE: Thoughts on a homemade regulator

Post  getback on Wed Dec 17, 2014 10:07 am

http://www.acehardware.com/search/index.jsp?kwCatId=&kw=red%20caps&origkw=red+caps&f=Taxonomy/ACE/19541496&sr=1 WOW they are proud of those little buggers / Yes I think it could be worthy of trying if the expense is to a minimum . I have TDs but have not got into flying them and feel I will have to resort to the bladder technique/ witch I have trying twice with out a good out come . Eric Snowman
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Re: RE: Thoughts on a homemade regulator

Post  roddie on Wed Dec 17, 2014 10:40 am

getback wrote:http://www.acehardware.com/search/index.jsp?kwCatId=&kw=red%20caps&origkw=red+caps&f=Taxonomy/ACE/19541496&sr=1 WOW they are proud of those little buggers / Yes I think it could be worthy of trying if the expense is to a minimum . I have TDs but have not got into flying them and feel I will have to resort to the bladder technique/ witch I have trying twice with out a good out come . Eric Snowman      

Holy s#i+.. $20 for a pkg. of 5 What? That can't be right.. A 10-pack is even more of a bargain @ $60... Shocked
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Re: RE: Thoughts on a homemade regulator

Post  Ken Cook on Wed Dec 17, 2014 3:17 pm

I will add this to the subject. Running on the bench will not insure you how the engine will run. It doesn't compensate for the air into the venturi or how the prop unloads. The way the engine behaves is not the same when it's in the air vs the bench.   When I've used smaller tubing from the bladder I found it becomes like breathing through a straw. You won't have enough fuel delivery into the engine and it will go over lean. This problem is even further complicated when the bladder starts depleting. You no longer have the pressure keeping the needle setting rich, the engine thus goes over lean. Bladders start out rich, they cause the engine to run leaner as they're depleting and the last bit of the run it goes rich.  Adding yet another obstruction is going to prove even more problematic. The proper needle takes all of the playing around out of the equation. On Cox related equipment, these needles are everywhere and plentiful. Why screw around with something that possibly won't work? A TD on suction works, it just doesn't work for me. While it may work on the stand, in the air for a while, somewhere through the run the engine struggles for fuel. A TD on a Perfect tank with the stock small tubing is VERY problematic. That's the worst design they could use and that tubing restricts the fuel flow too much. Point being, this can also happen when trying to do what your asking of certain tubing that will neck down the fuel flow.

         While on this subject, red caps will work but bladder tubing is far superior to it. The opening is too large and it requires tubing of multiple sizes to build it up large enough to make it work. I also see them being very short lived. They're very thin at the tip and I can see an aneurysm developing very quickly on these. Melvin from MBS Model Supply http://www.mbsmodelsupply.com/Ordering/Order.php has the best available with everything else needed. Ken
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Re: RE: Thoughts on a homemade regulator

Post  Cribbs74 on Wed Dec 17, 2014 10:13 pm

Ken,

I was thinking in terms of seeing if the engine will even run on the bench at all. I agree that it will tell you nothing about how it performs in the air. My thought was if it runs steady on a bench then it may be worth seeing if it will work in the air.

I also agree that it would be much easier to grab a needle, but sometimes money is tight.

Ron

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Re: RE: Thoughts on a homemade regulator

Post  batjac on Thu Dec 18, 2014 12:40 am

getback wrote:http://www.acehardware.com/search/index.jsp?kwCatId=&kw=red%20caps&origkw=red+caps&f=Taxonomy/ACE/19541496&sr=1 WOW they are proud of those little buggers / Yes I think it could be worthy of trying if the expense is to a minimum . I have TDs but have not got into flying them and feel I will have to resort to the bladder technique/ witch I have trying twice with out a good out come . Eric Snowman      

Wow!  You gotta be kidding me! Less than a minute of searching came up with this:

http://www.amazon.com/Piece-Little-Red-Cap-Caulking/dp/B00LI7HUNO/ref=sr_1_3?s=industrial&ie=UTF8&qid=1418885172&sr=1-3

I don't know how 50 cents a piece compares to using surgical tubing, but it might be a worthwhile alternative. But, I haven't tried bladder pressure yet, so I can't state a knowledgeable opinion.

The Outraged Mark
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Re: RE: Thoughts on a homemade regulator

Post  getback on Thu Dec 18, 2014 7:41 am

Thanks Ken , MBS looks like a good place to do some shopping I added to the fav. / I did a short search on the red caps for local PU .The 15.21 free s&h for 35 is better of coarse ACE is HI on there pricing .A BB in some silicone tubing would work for me . Cribbs is right about $ being tight sometimes nice to find the cheaper alternative . Eric Snowman
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Re: RE: Thoughts on a homemade regulator

Post  roddie on Sun Nov 01, 2015 4:06 pm

Too much fuel.. or not enough.. Huh... A few Sunday afternoon ramblings.. thanks in advance, for humoring me. I thought I'd share a few bits.. in the hopes it might help someone with a finicky set-up. I realize there's lots of variables surrounding reliable fuel-delivery.. and sometimes, what works on one engine might not work on another identical one.

I made a discovery while building the .049 reed-valve engine for the 1st CEF speed contest. I built my own hard tank and plumbed it (uniflow) with 1/8" copper tubes. The engine was fitted with a "killer-Bee" (large venturi) backplate and had a new Tee Dee cylinder. Initially; I tried using std. sm. 1/2A silicone fuel line.. and could not get the engine to run further than an exhaust-prime. I observed an air bubble forming in the line just before the engine would stop. My tank plumbing being 1/8" tubes, was more than adequate. Larger size line (less restrictive to flow) cured the problem of less suction being available.. because of the larger venturi.

I used simple compression-sleeves on the ends.. to reduce the ID to fit tightly on the smaller fittings.



This line would fit .35+ size engines.. but it worked for my app.



Here's another scenario.. say you have assembled a stock reed-valve engine for an external tank (suction).. but you're using a worn cylinder/piston assembly. Technically.. the reed is not lifting/flexing off the seat as much.. because there's less vacuum in the crankcase.. right? This would have an effect on drawing from a hard tank.. I would think. Especially if it's a Perfect/brand/style, with tiny tubes. I'd take Ken's advice on re-plumbing those to 1/8" tubing and thinking of it in terms of sucking liquid through a small straw.. as compared to a big one.

Getting back to a regulator (for pressure-bladder).. I assembled some small alloy tubing this afternoon, which spawned some thoughts on a simple yet crude way to experiment with metering. Looking at the photo below.. you see a tube within a tube. The smaller tube has the option of being crimped slightly on the upstream end.. making soldering unnecessary, because it wont slide through the larger one. It becomes an interchangeable "jet".. in a series that would be easy to make and try.

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