Is this enough prop?

**Cribbs74** Sat Jan 21, 2012 7:51 pm

For those wondering........(ya right) Laughing

I built the Texaco to clear the cowl pictured, now that it"s all said and done is this enough prop to clear the cowl?

[img] Is this enough prop? Photo_10

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microflitedude Sat Jan 21, 2012 7:56 pm

Looks better than the ol' GB R2..... Laughing

**Cribbs74** Sat Jan 21, 2012 8:07 pm

microflitedude wrote:Looks better than the ol' GB R2.....

What does? the prop,cowl or the clearance?

microflitedude Sat Jan 21, 2012 8:38 pm

cribbs74 wrote:
microflitedude wrote:Looks better than the ol' GB R2.....

What does? the prop,cowl or the clearance?

Clearance.

Mark Boesen Sat Jan 21, 2012 8:46 pm

thats great clearance, I've seen planes with less. What size is prop? and what are you gonna used to turn prop?

**Cribbs74** Sat Jan 21, 2012 10:23 pm

Mark Boesen wrote:thats great clearance, I've seen planes with less. What size is prop? and what are you gonna used to turn prop?

Prop is a 7x4, built a modified throttled Texaco like engine. I need to get a tach so I can figure out what it's turning. I don't need to worry about duration as it is externally tanked.

Mark Boesen Sat Jan 21, 2012 10:33 pm

I'm not sure if I'm right, but i'd think you'd want a low comp head with maybe 3-4 gaskets, dual port cylinder, so as much fuel/air flow as possible and a low compression head to fill up with a lot of fuel and air for a big bang to spin that larger prop.

**Cribbs74** Sat Jan 21, 2012 10:42 pm

Mark Boesen wrote:I'm not sure if I'm right, but i'd think you'd want a low comp head with maybe 3-4 gaskets, dual port cylinder, so as much fuel/air flow as possible and a low compression head to fill up with a lot of fuel and air for a big bang to spin that larger prop.

That's pretty much what I did, I posted a pic of it in the Cox discussions section if you wish to take a gander.

**RknRusty** Sat Jan 21, 2012 11:14 pm

cribbs74 wrote:
Mark Boesen wrote:I'm not sure if I'm right, but i'd think you'd want a low comp head with maybe 3-4 gaskets, dual port cylinder, so as much fuel/air flow as possible and a low compression head to fill up with a lot of fuel and air for a big bang to spin that larger prop.

That's pretty much what I did, I posted a pic of it in the Cox discussions section if you wish to take a gander.

I know you aren't going to run official Texaco races, but I'm wondering if you set it up to run like a Texaco engine? For instance a small Texaco sized venturi to restrict the fuel flow down to the Texaco spec? The small fuel flow is the heart of Texaco endurance performance; to fly the longest time on a 5 or 8cc tank of fuel. I think it has the smallest venturi of any Cox engine. But I cannot find any good info searching for it, so I'm just saying what I can remember about the Tex. I did read about one guy winning an event, flying the whole thing at about 4400 RPM.

nitroairplane Sun Jan 22, 2012 4:57 am

Yes the smallest venturi of the .049s I think he is running an external tank though.

**Cribbs74** Sun Jan 22, 2012 6:16 am

nitroairplane wrote:Yes the smallest venturi of the .049s I think he is running an external tank though.

Yep, I do have a correct backplate should the need arise however, I wanr this one to perform as well as possible as much thrust/rpm as the little .049 can give. I am going to build up an actual Texaco for future use on a slow flyer.

nitroairplane Sun Jan 22, 2012 6:18 am

Okay.
But if you want the best from a .049 turning a large prop diesel is the way to go.

**Cribbs74** Sun Jan 22, 2012 6:19 am

RknRusty wrote:
cribbs74 wrote:
Mark Boesen wrote:I'm not sure if I'm right, but i'd think you'd want a low comp head with maybe 3-4 gaskets, dual port cylinder, so as much fuel/air flow as possible and a low compression head to fill up with a lot of fuel and air for a big bang to spin that larger prop.

That's pretty much what I did, I posted a pic of it in the Cox discussions section if you wish to take a gander.
I know you aren't going to run official Texaco races, but I'm wondering if you set it up to run like a Texaco engine? For instance a small Texaco sized venturi to restrict the fuel flow down to the Texaco spec? The small fuel flow is the heart of Texaco endurance performance; to fly the longest time on a 5 or 8cc tank of fuel. I think it has the smallest venturi of any Cox engine. But I cannot find any good info searching for it, so I'm just saying what I can remember about the Tex. I did read about one guy winning an event, flying the whole thing at about 4400 RPM.

4400 RPM! Wow that is slow. I am surprised it was even firing down that low.

nitroairplane Sun Jan 22, 2012 6:21 am

cribbs74 wrote:
RknRusty wrote:
cribbs74 wrote:
Mark Boesen wrote:I'm not sure if I'm right, but i'd think you'd want a low comp head with maybe 3-4 gaskets, dual port cylinder, so as much fuel/air flow as possible and a low compression head to fill up with a lot of fuel and air for a big bang to spin that larger prop.

That's pretty much what I did, I posted a pic of it in the Cox discussions section if you wish to take a gander.
I know you aren't going to run official Texaco races, but I'm wondering if you set it up to run like a Texaco engine? For instance a small Texaco sized venturi to restrict the fuel flow down to the Texaco spec? The small fuel flow is the heart of Texaco endurance performance; to fly the longest time on a 5 or 8cc tank of fuel. I think it has the smallest venturi of any Cox engine. But I cannot find any good info searching for it, so I'm just saying what I can remember about the Tex. I did read about one guy winning an event, flying the whole thing at about 4400 RPM.

Yes they do and to do so they must run very lean and this is very hot and that is why the engines have the extra cooling.

4400 RPM! Wow that is slow. I am surprised it was even firing down that low.

**Cribbs74** Sun Jan 22, 2012 6:28 am

Indra,

I didn't see your plug for diesel till after I posted. Very sneaky my friend! I may try diesel one day. I have that .020 diesel head from you so really all I need is some fuel.

nitroairplane Sun Jan 22, 2012 6:44 am

Cool,
you may like diesel operation I like it as when I go flying I don't need to bring a glow start with me and if it is FF or CL I don't need to bring anything electric at all.

**Cribbs74** Sun Jan 22, 2012 7:14 am

True, your selling me! lol!

**RknRusty** Sun Jan 22, 2012 8:53 am

cribbs74 wrote:
4400 RPM! Wow that is slow. I am surprised it was even firing down that low.

Well now, I did read that on the Internet. So there is the slightest possibility it was exaggerated, but I guess it must've run pretty slow. I doubt if the plane could have been much more than 2 ounces plus the engine, and a big wing area.................... Now that you mention it, in the light of a fresh day, 4400 smells like BS. But I know nothing of larg props either.

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