Pulso-1 Plans metric does not = inches ???

[gone2fly]

I am looking at the Pulso 1 plans. Demensions are all in mm, the inch numbers written next to the metric numbers are not equal to the metric numbers. What is the deal with that?

Example tail pipe ID is listed as 45 and the OD is listed as 48, I assume that is mm.

45mm = 1.771"

48mm = 1.889"

1 53/64 = 1.828" a difference of .061" and .057" ?

also

8 holes in the valve plate 14mm each = .551" but it also says 9/16" which = .562" a difference of .011" ?

It seams logical to me to ignore the inch numbers, the metric numbers are probably correct. I am a machinist a plus or minus .001" is fine with me but plus or minus 1/16" does not work for me.

Has anyone built this engine?

The plans say nothing about the reed valve material or the thickness???

It does say 0,15 Dick, I have no idea what that means?

[phillip]

I would stick with the metric numbers on this jet as for the 0,15 Dick that is metric sometimes they use the (,) instead of the (.) and the Dick is a typo is should say thick so the thickness would be 0.005905 inches

[vturbine]

Did you see this?

viewtopic.php?f=2&t=5223

There was a mention of the valve holes being too small, I believe.

I'm also curious about the fuel jet and needle valve. Is the fuel gasoline? if so wouldn't it draw unevenly, since the orifice is below the centerline? If pressurized propane (or even pressurized liquid), I can imagine that the fuel would have some momentum, and then its position would be easier to understand.

Anyway, interesting engine. It looks like construction has been simplified over other valved engines in many ways. When I first saw this thread, I found another "pulso" engine plan for a French engine. Much more complex construction -- especially the injector and the necking of the tail tube.

[Rocket Man]

Did you see this?

viewtopic.php?f=2&t=5223

There was a mention of the valve holes being too small, I believe.

I'm also curious about the fuel jet and needle valve. Is the fuel gasoline? if so wouldn't it draw unevenly, since the orifice is below the centerline? If pressurized propane (or even pressurized liquid), I can imagine that the fuel would have some momentum, and then its position would be easier to understand.

Anyway, interesting engine. It looks like construction has been simplified over other valved engines in many ways. When I first saw this thread, I found another "pulso" engine plan for a French engine. Much more complex construction -- especially the injector and the necking of the tail tube.

According to my calculations the drawing has some problems. But if the engine actually runs that is another story.

Cross sectional area of exhaust tube = 2.802

Cross sectional area of combustion chamber = 10.985

Pulso-1 Ratio = 3.92 to 1

German V1 ratio = 2 to 1

Dyna Jet engine ratio = 3.898 to 1

Cross sectional area of the air intake = 1.907

Pulso-1 air intake Ratio = .68 to 1

German V1 air intake ratio = .5 to 1 designed for 450 mph ram air.

Dyna Jet air intake ratio = .8 to 1

You are correct air intake for Pulso-1 is small. The engine may be designed to run at 75% throttle at static thrust or to protect the reed valves. The engine and RC airplane my be designed so ram air will increase the fuel pressure exactly like the German V1 in that case the air intake is sized correctly considering the air speed is about 200 mph.