RE: Thoughts on a homemade regulator

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

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?

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

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?

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)

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.

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.

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

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      

Holy s#i+.. $20 for a pkg. of 5 That can't be right.. A 10-pack is even more of a bargain @ $60...

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

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      

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

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

Too much fuel.. or not enough.. 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.