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Old Dec 29, 2012, 01:37 PM
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Fokker DII's Avatar
USA So. Cal.
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Originally Posted by flyinwalenda View Post
I haven't started mine yet(getting dumped on with snow today...joy) but I would say any air leaks in this system will quickly affect the carb. Also as mentioned I'm wondering how this system will perform inverted. We will see !
Mine flys fine inverted. Now that I put it into a 40 size plane. The 60 that I started with was too heavy for this engine. A 40 size Escapade is perfect.
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Old Dec 29, 2012, 02:18 PM
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DarZeelon's Avatar
Israel, Ramat HaSharon
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No, I do not, Fokker.

I was contemplating... Until I read this.
Muffler pressure provides just a bit more pressure, that aids fuel suction and slightly improves its reliability.

In fact, it seems this engine with its elaborate carburettor, would work equally well, if the normal Evo .60NX's carburettor was installed on it.
Yes, it has a built-in regulator. But I cannot see why they put it there; since exhaust pressure is very low, compared to the integral pump's pressure.

A normal R/C carburettor (without a regulator) should work just as well.
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Old Dec 29, 2012, 03:15 PM
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Fokker DII's Avatar
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Originally Posted by DarZeelon View Post
No, I do not, Fokker.

I was contemplating... Until I read this.
Muffler pressure provides just a bit more pressure, that aids fuel suction and slightly improves its reliability.

In fact, it seems this engine with its elaborate carburettor, would work equally well, if the normal Evo .60NX's carburettor was installed on it.
Yes, it has a built-in regulator. But I cannot see why they put it there; since exhaust pressure is very low, compared to the integral pump's pressure.

A normal R/C carburettor (without a regulator) should work just as well.
What???
I fail to follow your process. This carb, per the manual, does NOT have an integral pump hense the use of regulated muffler pressure.
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Old Dec 29, 2012, 03:15 PM
nickeast
Stuart,FL
Joined Mar 2009
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Dar,

I think that it is spelled "Carburetor" to start with and I, like everybody else here, have an interest in hearing facts and valid information. Horizon Hobby seems to be the best source. People with direct knowledge... i.e. ... "They own one" are also valid sources of knowledge and as far as I’m concerned, it seems to me that you have some other motive and spend a lot of time being disruptive without actually contributing anything. The Horizon Guys have seemingly gone away rather than deal with you. I am amazed at the number of posts that you have made and actually said nothing valid about a product that you don’t even own. Give the rest of us a break…..

Nick
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Old Dec 29, 2012, 03:51 PM
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East Texas
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Dar... it was you that suggested fuel to air ratio was more critical with gas compared to glow. Perhaps the very low consumption rate was easily overwhelmed by gravity feed (descending) compared to suction feed (climbing).

It actually makes quite good sense why a regulation system is/was needed. In a pump/regulator system the regulator is needed to provide a constant reference to wit the needles can be set and it happens that atmospheric pressure is convenient. The pump provides a constant overhead pressure, which admittedly plays a key role.

We know that gravity systems never used a pump. I'm wondering if the system employed might be considered a hybrid of gravity. pump and draft feed. While the pump pressure is too low to normally be considered effective, perhaps in conjunction with the other two.... it works.

WARNING a soap box rant follows... if you dislike rants... read no further

I once bought a NIB YS 1.20. I fought that animal for three weeks and it won the temperament battle as I concluded it was no friend of the sport flier wishing to have fun. It pressurized the tank (considerably) and then regulated the pressure. I've thought it would have been more successful had it used atmospheric regulation but those who were smart enough or perhaps lucky enough to make them run good would scoff at my thinking. A disclaimer is that I'm a sport pilot who was running club 15% fuel and determined from the outset that I'd not buy high nitro to fly sport... if it didn't run on what I was running, I didn't want it. I still have it because I won't sell the headache to someone else though I have tried to give it to friends... with each declining... my friends are smart, eh.

Again... just as in NGH, that was another animal that doesn't directly bear on the Evolution 10cc but it does suggest that fuel flow isn't all simple or is it?

SHORT STORY for those who are still reading

At the field one day, an old geezer had inadvertently left his needle valve on the work bench at home after replacing a cowl. We began to take notice that he hadn't packed it in and watched as he slid a short section of fuel tubing over the needle assembly and plugged it with a small twig. Taking two additional twigs, he bound them together on one end with some wire and slid the fuel feed line between and then wrapped wire around the other end making a twist knot to tighten with pliers. Within a few short engine runs with increasing tension twisting on the wire, he had the engine singing a tune and flew several flights.
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Old Dec 29, 2012, 03:51 PM
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I do not have any problem understanding how the Evo 10cc engine's carb works. it will work fine, except in those situations where it has a poorly located fuel tank position. But then even a glow engine would have the same problems too. So the Evo 10cc carb will work fine. Evolution and their testing teams have had several years of working with it to iron out the problems already. They did not rush their product to the market either.

Walbro also makes quite a few different carburetor versions that have no pump, but they all do have a regulator. I remember counting up something like over 20 different carb versions like that too. So obviously a engine with those types of pumpless carbs would work fine. Otherwise they wouldn't do it.

Actually when I was a kid flying control line. I had crashed my plane and it broke the needle valve off. I didn't have a way to get a new needle valve right away. So I used a piece of metal bent over with a nut and screw to serve as a clamp on the fuel line and I clamped the fuel line just right to have the engine run Ok again. I flew the plane with the engine like that for quite a few flights too. Most of the summer actually.
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Old Dec 29, 2012, 05:44 PM
nickeast
Stuart,FL
Joined Mar 2009
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Does anybody have any idea of the amount of thrust we can expect (in pounds) from this little beast?

Nick
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Old Dec 29, 2012, 06:34 PM
Two left thumbs
Muncie, IN
Joined Sep 2006
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Originally Posted by earlwb View Post

Walbro also makes quite a few different carburetor versions that have no pump, but they all do have a regulator. .
If this is correct, you're teaching this eighteen-year veteran of the small engine repair business something new! Except for their line of float type carbs, which ones don't have pumps? I've seen diaphragm type Tecumseh and TK gravity flow carbs, but never a Walbro!

Geoff
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Old Dec 29, 2012, 06:37 PM
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East Texas
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We can probably assume that thrust is between a .46 and .60. IIRC, Pete characterized it as closer to a .60 than .46. Does that sound like a .55?

I'm putting mine on a Seagull Funfly 3D and hope to stay under 6lbs but haven't a clue if it will hover as the 3D stuff isn't all that interesting to me.

The Funfly 3D calls for a .46-.55 so the Evo 10cc is at the upper end of the range except it perhaps being heavier with the gas engine. There will be a 4oz compensation for lighter fuel load and possibly a slight bit for using LiFe battery.

I'd hazard a guess 5.25 - 6.25 lbs and lean on the upper half but wouldn't be surprised if it is the lower.

The upper half is probably wishing.
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Old Dec 29, 2012, 06:38 PM
EIEIEIO Classic is dway ta go!
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Northeast Pa. .Heyna or No?
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Quote:
Originally Posted by Fokker DII View Post
Mine flys fine inverted. Now that I put it into a 40 size plane. The 60 that I started with was too heavy for this engine. A 40 size Escapade is perfect.



Good to hear.
Yes, a 60 size Escapade has a long heavy tail ! More suited for a 90 !
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Old Dec 29, 2012, 08:11 PM
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Quote:
Originally Posted by GeoffinIN View Post
If this is correct, you're teaching this eighteen-year veteran of the small engine repair business something new! Except for their line of float type carbs, which ones don't have pumps? I've seen diaphragm type Tecumseh and TK gravity flow carbs, but never a Walbro!

Geoff
For example a WA 159 is just one example. It also gets its fuel through the bottom of the base gasket too. No fuel fittings on the carb itself. Only a fitting for the breather vent on the regulator. It draws fuel through a hole in the base of the carb. Odd needle valve placement as well. No choke either, nor a primer bulb attachment as well. I think the carb was used on the HOMELITE ST-80,ST-100 units.

It looks normal from this side.


it has a fitting for the breather part of the regulator to connect to the air filter.


They didn't even bother to machine the fuel pump side of the WA-159. Go figure.


Odd placement for the low and high speed needles too.
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Old Dec 29, 2012, 08:27 PM
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Originally Posted by nickeast View Post
Does anybody have any idea of the amount of thrust we can expect (in pounds) from this little beast?

Nick
According to their RPM numbers for the 10cc engine it is developing around .9HP and developing around 6 pounds of thrust static (7 pounds free air). it depends on the propeller as to how much thrust you can get. It could be a little more or a little less. One could prop it with a larger prop or a smaller prop, but then it might take it out of its best powerband and so you might wind up losing power then. A smaller prop would have less thrust, but more speed. A larger prop more thrust but less speed. A 10x6 for example yields around 5 pounds of thrust static with a speed of around 77mph. A 12x6 prop yields around 6 pounds of static thrust with a speed of around 63 mph (7 pounds free air)
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Old Dec 29, 2012, 10:53 PM
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On hand are a 10x6 and 11x6 props to break in with... but coming is a 14x4w funfly prop to try after break in. If it loads heavy, it can be shortened. With the thick long foil and generous wing area of a funfly type plane, low speed torque will be wanted over speed. We'll see how it goes.

An engine with a wide thrust band and prop selection is kinda neat.
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Old Dec 30, 2012, 12:00 AM
nickeast
Stuart,FL
Joined Mar 2009
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Thanks for the answers ... I'm sure that I'm seeing one of these in my future. 7 pounds of thrust is just right... the plane is going to be built right and should be about 6 pounds when finished. I like to build strong but light... it's supposed to fly ...

Earl, I should be out in your neck of the woods in the Spring.... Esparza's (SP) is one of my favorites....

Nick
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Old Dec 30, 2012, 12:22 AM
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Israel, Ramat HaSharon
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Originally Posted by nickeast View Post
I think that it is spelled "Carburetor" to start with and I, like everybody else here, have an interest in hearing facts and valid information.

OK, Nick, Fokker.

I get why the regulator was preferred to a simple carburettor (this is the Commonwealth spelling), as well as why it should work more satisfactorily.

But still, the absence of the pump and the reliance on the very low muffler pressure, will, I believe, make it not run as well.

If a part can be done without; the manufacturer of an engine will not bother to install it. An unnecessary part not installed costs him nothing and its absence is unfelt...
Yet, all other current hobby gas engine manufacturers did select to have the pump there, including Saito, which is also represented by the same Craig, Pete and Jim of Horizon Hobby; and which (as you wrote) selected to 'cop-out' rather then to contend with my very valid arguments.


I must remind you of this: In 1955, Chevrolet introduced the original the 265 cid Small Block engine, that did not have an oil filter...

I hope Horizon Hobby's choice to leave the pump out, does not prove to be a similarly damaging oversight.
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