Originally Posted by japan3d

Sounds like you were a heli mech.

Yup, CH-46 Flightline Mech 6112.

oh ya, GROUND RPM's don t mean a dang thing

Originally Posted by pe reivers

Unmanned,
Stall is when the prop or wing starts loosing lift. Props with pitch/diameter ratio of less than unity do not stall. Most of the foils used in our props need an angle of attack in excess of 15° to enter a stalled condition. You can do the math yourself if prop jetstream speed is known.

Again, let it be said that in static condition the prop is used as air brake, and most of our props are at max thrust condition as well (non-stalled condition). Since there is no forward speed, the classic propeller efficiency is ZERO, but who cares. It is the rpm numbers we can use to define engine output power and thus compare engines across users. More/less rpm means more/less power (if same prop is used). That is what this thread is all about.

Precisely. Some folks like to believe that static rpm numbers don't mean anything, but engines that are weak on the ground are also weak in the air. A miracle doesn't occur when engines become airborne.

Originally Posted by Diablo

Precisely. Some folks like to believe that static rpm numbers don't mean anything, but engines that are weak on the ground are also weak in the air. A miracle doesn't occur when engines become airborne.

Originally Posted by pe reivers

Unmanned,
Stall is when the prop or wing starts loosing lift. Props with pitch/diameter ratio of less than unity do not stall. Most of the foils used in our props need an angle of attack in excess of 15° to enter a stalled condition. You can do the math yourself if prop jetstream speed is known.

Again, let it be said that in static condition the prop is used as air brake, and most of our props are at max thrust condition as well (non-stalled condition). Since there is no forward speed, the classic propeller efficiency is ZERO, but who cares. It is the rpm numbers we can use to define engine output power and thus compare engines across users. More/less rpm means more/less power (if same prop is used). That is what this thread is all about.

Exactly, and with that spread sheet of yours you can obtain a lot of useful information, use it all the time. Thanks again

DLE111 About 3 gallons of use
Xoar wood 27x10
Regular gas with amsoil
Proflow canisters
6200 feet high

6600 Rpm

Here is a vid taken the other day. It is my first DLE-20 on stock ring stock ignition, running 32-1 syn...about 4 gallons. We are about 15 feet above sea level, 86 degrees F. [Edit in, 8700 hot rpm]

Y'all let me know if you can tell where the hump is?

BTW I used the exact same Xoar 17x6 prop off of my new WWRC 20cc Sbach that I saw almost 9k with updated ignition and Bowman ring and same muffler... Might be approaching 3/4 of a gallon by now on that engine.

Will shoot a vid of that one soon.

DLE 20 on WWRC Performance Muffler (3 min 4 sec)

don't you just love it now when we talk engines and rpm.we have to say weather or not a replacement ignition or a Bowman ring is or isn't being used, on a brand new engine.
do you think Frank has any offers from engine companies to use his rings as stock items?

Speaking of rpm, here is one from today.

DA-60 with RE2 pipe, Stock length MTW header from DA, .25" gap in coupler.
Mejlik C.F. 24x10 prop.
Premium pump gas with 32-1 Stihl Ultra HP.
New engine with only two flights on it.
Tached right after landing
6780~6800 rpm

About 65 or so degrees out, humidity 60% and 1500' ASL.

This a different DLE-20, Started with a new Bowman ring in a new engine. Now at 3/4 of a gallon of Penzoil Aircooled at 32 to 1.

I used the exact same Xoar 17x6 prop that was on the engine in vid three posts ago. Same WWRC profile muffler, got an extra 120 hot rpm. I dont know how much more breaking in will be with the ring/engine, as it seems to be running great right now.

I tach the engine three times in the vid. Getting 8820 most consistently. The big thing for me is (you can see in first minute of vid) that there is no ignition dump from around 28 to 3200 rpm like there is in the other vid. The standard Rcexl ignition does not take all of the timing out at once like the DLE 20 ignition.

The little engine runs great and drags the plane that is right at 9 pounds fueled... like a rag doll... WW

20cc Sbach (10 min 38 sec)

DLE 30 with a single bolt conversion and Frank bowman ring, 8990 rpm

Very informative....lol.

Da-120. 10k.

da120- 0000, cause its off and im on my computer

thread states Real World RPM.

Originally Posted by closetguy

thread states Real World RPM.

Oh now you just ruined it....