PuttPutt first flight 2014

[rockiedog2]

>>>I was kinda expectin' you to come back in line with what the prop calculators predicted once you got tired of the 60" creating more howl than practical thrust.

well that got me trying to remember all the details on the diff props and couldn't so went back and checked the notes. the original goal was to find a prop for max climb and i assumed that would come at rated power of 3600 so that's what we started working toward. i havent looked at any prop calculators since the first prop.

the only 6020 i tested was a tennessee on the zenith motor and it wouldn't turn up atall not surprisingly(or howl). i ended up cutting it all the way down to i think it was a 56 and it still wouldn't turn up or climb. even reduced the pitch using Kiblinger's method still wouldn't turn up. the notes said i think the climb was 500+- fpm. i put the old prop off of the 37 and it turned it same as the 37 did. that adds up since we later found out with Kiblinger's club that's what it was making. the tenn is wall art. i true POS IMO compared to Frank's props. i put dual mikunis on it and started over on the props. so never did really get a real test on a 6020.
the one that howled so nice was a 5820. it also produced the most climb but not the most rpm in the climb. average rates with it were about 765. the howl was due we think not from tip speed but from cavitation of the very thin blade tip(it would only turn about 3450 in the climb and we were looking for 3600. the howl came on at 3660 in level WOT flight). so Frank made up a 5818 with thicker camber to eliminnate the cavitation and it wouldn't turn up or climb as well due the sensitivity of the Half to prop drag caused by the thicker camber. so it went back to Frank and he thinned it out and reshaped the blades slightly and the tips cavitated on it so to salvage it i clipped it and  it does pretty good. excellent in fact especially compared to the tenn. the climb rpm went up slightly but the rate went down slightly to 750 average. i cal that diminishing returns when going below 58 if all else is kept near the same. well that's my conclusion anyway. for max climb the ideal length i think is a 58. but if there's a proper 57 laying around it'll sure do a good job. and i had one here so it'll get run since it does so well. it's ok. my favorite prop the 5820 bit the dust literally at osh.
i concluded also that it wasn't reasonably possible to make a Half turn a 58 up to 3600 in the climb...but to go below that was to get into the diminishing returns. the Half is also very sensitive to tip thickness etc and responds big time to increases/decreases in prop drag. that's what I remember...if Frank has diff words on it I defer to him as he was the one making them.

 >>>git a stick with a bit more pitch.

i cant really do that around here cause i got such a crappy strip with all these downdrafts, trees etc. i gotta have max climb; that was the reason behind all the prop experiments. and i still do like that howl. it'll wake up this here bottom.

Spencer

[Sam Buchanan]

the only 6020 i tested was a tennessee on the zenith motor and it wouldn't turn up atall not surprisingly(or howl). i ended up cutting it all the way down to i think it was a 56 and it still wouldn't turn up or climb. even reduced the pitch using Kiblinger's method still wouldn't turn up. the notes said i think the climb was 500+- fpm. i put the old prop off of the 37 and it turned it same as the 37 did. that adds up since we later found out with Kiblinger's club that's what it was making. the tenn is wall art. i true POS IMO compared to Frank's props. i put dual mikunis on it and started over on the props. so never did really get a real test on a 6020.

<snip>

i cant really do that around here cause i got such a crappy strip with all these downdrafts, trees etc. i gotta have max climb; that was the reason behind all the prop experiments. and i still do like that howl. it'll wake up this here bottom.

Spencer

So are you really sure the Tenn Prop was as bad as you said it was since you never flew it on the dual-carb engine? Sounds like you are comparing it to Frank's props even though it was flown on a different engine than you now fly. After chopping the 60x20 down to 56" it must have had some horrendously wide tips. We know now the single-carb engine won't wind up to 3600 with any appropriately sized prop. I flew a 58x22 Tenn Prop on my single-carb engine and it flew pretty well, about 250 rpm higher (and 5mph slower) than my 58x24 Tenn Prop. Would be interesting to see if the dual-carb engine would wind it up.

I'm sure Frank's props are very nice, I have no reason to doubt that. Just wondering if we have a valid comparison since the engine and Tenn Prop were modified in the process of prop testing. Changing three variables at once and all that stuff......

I find the prop stuff to be interesting/confusing/frustrating/and very interesting because we often find out that what we thought we knew we really didn't know. These little engines leave precious little margin for mis-propping. I wonder what Frank's current recommendation is for someone who wants to order a prop for their 45.

But if you have something that works for you that is all that matters. Yep...gotta keep the bottom awake.  ;D

[CHARLES DEBOER]

" I wonder what Frank's current recommendation is for someone who wants to order a prop for their 45."

Just got a recommendation from Frank on my duel carb 45.  It was a 58 X 20, $325.00 for delivery in August - September.

[Sam Buchanan]

Just got a recommendation from Frank on my duel carb 45.  It was a 58 X 20, $325.00 for delivery in August - September.

Thanks Charles, that's good info for the group to have.

It is interesting that 58" seems to be the diameter the 45 is happy pulling. The 20" pitch on the dual-carb engine should yield a similar speed envelope as the 54x20 common on the smaller engines but the additional 4" of diameter produces more climb than the smaller engines. I realize different prop manufacturers measure pitch in different ways but this should be a valid generalization.

I don't know if many single-carb 45 engines will now be ordered but it tosses a different wrinkle into the discussion because it develops max power at a lower rpm. Guess that is why 24" of pitch is working well on XL-58, I never see more than 3000 rpm with that combination. But it yields a pleasant flying experience that is closer to what we see with slower-turning conventional engines.

My guess, and it is just a guess since there has been no empirical data collected as far as I know, is the two engines develop similar power at 3000 rpm, but while the single-carb engine runs out of breath at ~3200 the dual-carb can breath deeply enough to spin a bit faster. We still don't know what a dual-carb 45 can do with 24" of pitch...it might be a fantastic combination of exceptional climb and relaxed cruise.

[weasel]

spencer,  you gonna be alright over there?   

That prop noise got you on a rampage.   I wanna see sams prop run on your plane back to back testing on the same day.  I will chip in some on the effort.  will help ya change it out and hold wrenches for ya.  Might even sweep your shop floor or mow the runway if that makes it happen

Weaz

[rockiedog2]

spencer,  you gonna be alright over there?  



Weaz

nawman  everybody over here has lost it

[Skyboltone]

The thing I noticed is how much the engine moves around on final approach!

with the motor at about 2500rpm the airframe vibes, including where the vid is mounted. That's most of what looks like motor rolling around.

glad to have you here. cool dawg you got there, or is that a pic of you?

if you get an Eagle built you'll like it

Joe

  

 I don't remember exactly if that's me or the dog up there.  Goog looker either way eh?  She's a good girl and loves to go anywhere I go but she's too dang big for the Luscombe so I don't know that's she'll ever be a flydog.  Those ears would help though.  


There's a LE built fuselage on gear with ribs built and ready for spars and all the rest local here the guy wants $1800.  I'm outa money though.  Saving for the Zenith motor right now.  This here is a fun bunch though.

[rockiedog2]

  

I don't remember exactly if that's me or the dog up there.  Goog looker either way eh?  She's a good girl and loves to go anywhere I go but she's too dang big for the Luscombe so I don't know that's she'll ever be a flydog.  Those ears would help though.  


There's a LE built fuselage on gear with ribs built and ready for spars and all the rest local here the guy wants $1800.  I'm outa money though.  Saving for the Zenith motor right now.  This here is a fun bunch though.

we had a ragwing 8A when I was a kid. ol George a 100# retriever used to love to ride in it. he liked to ride and look but hated spins