RunRyder RC
WATCH
 2 pages [ <<    <    ( 1 )     2     NEXT    >> ] 2290 views POST REPLY
HomeRC & Power✈️Aircraft🚁HelicopterEngines Plugs Mufflers Fuel › Uniflow fuel system !!
01-10-2013 09:08 AM  7 years ago
Topic Vote0Post 1
darren heaver

rrApprentice

rochester, kent, england.

MyPosts All Forum Topic
Uniflow fuel system !!
Does anyone still use the uniflow fuel system on a non regulated nitro engine ? Just thinking about giving it a go !!

Any new feedback ?

Cheers Darren.
" one day I will learn to fly till then I will just hover"
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
01-10-2013 10:39 AM  7 years ago
HeliPhil

rrApprentice

Brentwood, Essex, UK

MyPosts All Forum Topic
I always used a uniflow system - works much better
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
01-10-2013 10:43 AM  7 years ago
darren heaver

rrApprentice

rochester, kent, england.

MyPosts All Forum Topic
Cheers HeliPhil will give it a go then. It does make sense but just can't see why people don't use it more ? and they just accept that the heli will go leaner at end of flight is it laziness or lack of understanding of how it works

Cheers anyway
" one day I will learn to fly till then I will just hover"
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
01-11-2013 05:08 AM  7 years ago
Dr.Ben

rrMaster

Richmond, VA, USA

MyPosts All Forum Topic
Some reasons...

1.Tank set up is more complex initially.

2. Fueling must be done in the correct manner to avoid flooding the muffler.

3.Not enough veteran modelers around to teach the technique.

4. Pressure regulated engines much more common.

5. Per unit of displacement, modern engines are much more powerful than those of the past.
we no longer need to needle engine on the ragged edge to get good power.

And really most importantly.....

Most engines these days use three needle carbs which typically avoid the propensity for to run lean in the midrange. In the old days with ill designed two needle carbs, even a well needled engine had the tendency to get lean especially in the midrange as fuel level dropped. With better designed carbs such as found on the OS HZ series of engines, we can tune the midrange to be consistent with the high, so that if you start with the needle just a fuzz rich, the little bit of leaning that occurs as fuel level drops is largely insignificant and unnoticed.

Ben Minor
Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
01-11-2013 06:37 AM  7 years ago
darren heaver

rrApprentice

rochester, kent, england.

MyPosts All Forum Topic
Cheers for that Ben. Will have a think about it as the engine I have is a 2 needle and its for the GF to learn with so want it as stable and consistent as possible for her so may give it a go.

Cheers Darren.
" one day I will learn to fly till then I will just hover"
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
01-16-2013 06:20 PM  7 years ago
fastrc1

rrKey Veteran

Planet Brooklyn, NY-USA

MyPosts All Forum Topic
Wowww. I used to fly uniflow on my Pro 2K way back when.RIP Roman Pirozek Jr.
Team Futaba USA
Team Kontronik USA
http://flysrw.com
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
01-16-2013 07:46 PM  7 years ago
darren heaver

rrApprentice

rochester, kent, england.

MyPosts All Forum Topic
They say things come back in fashion lol lets make this one of them " one day I will learn to fly till then I will just hover"
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
01-17-2013 12:01 AM  7 years ago
KevinB

rrKey Veteran

Earth

MyPosts All Forum Topic
I still use uniflow on my Fury Extreme using an OS91 C-spec w/ Viperhead and original Muscle Pipe Works fine.

KevinB
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
01-18-2013 06:59 PM  7 years ago
darren heaver

rrApprentice

rochester, kent, england.

MyPosts All Forum Topic
I have plumbed it for uniflow now but just not had time to get it into the air too busy doing DIY but once house is finished it will be play time every day hehe . Can get some of the scale machines finished

Cheers for the feedback
" one day I will learn to fly till then I will just hover"
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
01-18-2013 09:50 PM  7 years ago
G-Limo

rrApprentice

Europe

MyPosts All Forum Topic
SHARE  PM  EMAIL  Attn:RR  Quote
01-27-2013 12:19 AM  7 years ago
DGS

rrNovice

Hamburg, NY

MyPosts All Forum Topic
I have run a uni-flow setup on a 50 for several years. Just set up another heli with it. It works well. It's pretty simple once you get used to the couple extra steps needed.
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
01-27-2013 08:09 PM  7 years ago
darren heaver

rrApprentice

rochester, kent, england.

MyPosts All Forum Topic
Cheers for that I have plumbed it but just not had time to try it as of yet " one day I will learn to fly till then I will just hover"
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
02-01-2013 04:42 AM  7 years ago
Zaneman007

rrElite Veteran

Texas - USA

MyPosts All Forum Topic
Curious
I went to the link to see how this was done.

I don't get it. Am I missing something? It seems like it would reduce the overall pressure to the tank, thus requiring the needles to be richer to obtain the same amount of fuel. Although the reduction in pressure would lead to a lesser lean condition as the tank got lower, It would seem that your creating a leaner condition to start with.

If you plumbed it the way it was designed, the only difference would be a greater variation in presser between a full and empty tank.

My point is what is the benefit to doing this.

And the down side is obviously a muffler full of fuel, consistently.
Old Guys Rule!
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
02-01-2013 05:14 AM  7 years ago
KevinB

rrKey Veteran

Earth

MyPosts All Forum Topic
Zaneman007,

Yes, you need to use a shutoff clamp on your muffler pressure line when refueling.

You have got the idea. Plumbing the muffler pressure to a clunk so that it enters the tank under the fuel load, basically decreases the pressure a bit at full tank because the weight of the fuel is pushing against the muffler pressure.

SO.......... you MUST richen the needles to counter for this lesser fuel pressure overall when tuning your engine. (compared to a normally plumbed pressure line)

The benefit comes as the fuel is burnt. The less fuel weight pushing against the muffler pressure entering the tank, the more effect the muffler pressure has on the fuel tank pressure. So the fuel pressure at the carb sort of "balances out" as the tank empties.

Trust me......it works. The slightly decreased muffler pressure is still enough to provide positive fuel flow, and you don't get the leaning effect as the fuel load goes down.

STANDARD SYSTEM:
Fuel pressure at carb = muffler pressure + fuel weight pressure

UNIFLOW:
Fuel pressure at carb = (muffler pressure - fuel weight press.) + fuel weight press.
aka.....the fuel weight cancels out and you are left with just
Fuel pressure at carb = muffler pressure (regardless of fuel level)

So the Uniflow system takes the extra head pressure of the fuel weight out of the equation and you have a consistent mixture from full to empty.

KevinB
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
02-01-2013 02:29 PM  7 years ago
darren heaver

rrApprentice

rochester, kent, england.

MyPosts All Forum Topic
Still not tried it as not been flying but am convinced it will work and I always wondered why people used to say about the heli going lean as fuel goes low and could not see why they had done anything to correct it, but they had but people just don't or can't be bothered to use it !!! They are quite happy to put up with thing's being nearly there but not correct ;-) lol

Good luck will feed back once tried it.
" one day I will learn to fly till then I will just hover"
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
02-01-2013 02:36 PM  7 years ago
G-Limo

rrApprentice

Europe

MyPosts All Forum Topic
So guys, how does this differ from traditional 'Muffler Pressure' fuel system. It appears to be the same..

A sealed filler pipe into the Fuel tank and an open pipe from the muffler to pressurise the Fuel tank..

/Limo.
SHARE  PM  EMAIL  Attn:RR  Quote
02-01-2013 03:31 PM  7 years ago
darren heaver

rrApprentice

rochester, kent, england.

MyPosts All Forum Topic
Dave if you look at the drawing the muffler pressure is fed into a clunk and into the bottom of the tank and in effect seals the tank and has the fuel weight acting on it to balance the pressures out. I think but you loose pressure from the muffler because you are acting on the fuel in the tank hence the richer needle setting because the fuel pressure at carb is lower but more stable. I THINK

Sounds good anyway
" one day I will learn to fly till then I will just hover"
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
02-02-2013 04:23 AM  7 years ago
ICUR1-2

rrElite Veteran

Ottawa, Ontario

MyPosts All Forum Topic
💎Sustaining Member
could the same thing be accomplished with a check valve ?spending time, paying attention
SHARE  PM  EMAIL  GALLERY  Attn:RR  Quote
02-02-2013 09:09 AM  7 years ago
helixangle

rrKey Veteran

Mamaroneck, NY - USA

MyPosts All Forum Topic
wouldn't a scupper work on the muffler side.

A free flow check valve, no pressure build in the line necessary to open, yet directional preventing pressure / fuel back flowing to the muffler

rock on atmosphere...rock on!
Be sure the juice is worth the sqweeze
Remember life is hard...even harder for stupid people
SHARE  PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
02-02-2013 11:28 AM  7 years ago
G-Limo

rrApprentice

Europe

MyPosts All Forum Topic
I thought the whole idea of the pressure system driven by the Exhaust Pressure is to remove the lean run at high throttle openings, when the exhaust pressure and fuel demand is at it's greatest. Once the throttle is closed and the exhaust pressure reduces, the fuel pressure would reduce also and not flood the engine...

The 1 way valve would keep this higher pressure in the tank. Also the flow pressure to overcome the spring in the 1 way valve would reduce the effect of the exhaust pressure at low engine RPM..

Constant +atmospheric pressure in the fuel tank would also require the use of an 'on demand' fuel regulator in sync with the volumetric requirement of the engine ie. the YS or OS fuel flow/reg systems..

/Limo.
SHARE  PM  EMAIL  Attn:RR  Quote
WATCH
 2 pages [ <<    <    ( 1 )     2     NEXT    >> ] 2290 views POST REPLY
HomeRC & Power✈️Aircraft🚁HelicopterEngines Plugs Mufflers Fuel › Uniflow fuel system !!
 Print TOPIC  Make Suggestion 

 6  Topic Subscribe

Monday, April 6 - 11:08 pm - Copyright © 2000-2020 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online