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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/4/2012 10:05 PM   
Ernie Misner



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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/4/2012 10:52 PM   
ahicks


 

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Status: offline 		Ernie - nothing as far as performance, a little different, maybe muted slightly, exhaust note. That's me though, and nothing very scientific for a test one vs. the other.

microdon2 - switch to that 3 bladed prop at the field while 2 blade performance is still fresh in your head. Betting you won't leave the 3 blade on for long. Looks cool, but you take a big performance hit...

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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/4/2012 10:54 PM   
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Status: offline 		 Acdii, do you mean it will kill the engine, or, it will be "very nice"? Just to be sure!

Ernie Misner, I bought the JTEC muffler just to add a better look to my scale plane! Not sure how much it will help on performance. But I will try to find out!


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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/4/2012 11:00 PM   
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Status: offline 		ahicks - I wasn't commenting on the performance of the three-blade prop, just that the engine would not be underpropped. The 14x9 prop would probably produce the same load as a 15x10. But agreed - everything I've read says that three-blade props are not as effecient (due to increased turbulence?) as a two blade.

My understanding of mufflers - and I could be wrong, is that a better muffler will do a better job of lowering the decibel output but at the cost of some RPM. Am I wrong on that?

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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/4/2012 11:05 PM   
Ernie Misner



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Status: offline 		A tuned canister or muffled tuned pipe will actually increase power with less noise. Small deflector type mufflers seem to rob rpm's at the cost of less noise modifications. There's the Snuffler (Troy built models?) that sticks into the muffler outlet costing a couple hundred on the top end they say.

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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/5/2012 12:17 AM   
acdii


 

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quote:

ORIGINAL: Guijs

 Acdii, do you mean it will kill the engine, or, it will be "very nice"? Just to be sure!

Ernie Misner, I bought the JTEC muffler just to add a better look to my scale plane! Not sure how much it will help on performance. But I will try to find out!


Very nice.  Underpropping would more likely kill the engine. Over rev one and it could go boom.


quote:

ahicks - I wasn't commenting on the performance of the three-blade prop, just that the engine would not be underpropped. The 14x9 prop would probably produce the same load as a 15x10. But agreed - everything I've read says that three-blade props are not as effecient (due to increased turbulence?) as a two blade.


I'm thinking its the other way around, a 15x9 vs 14x10 would be about the same load. The lower pitch would give higher revs.

As far as fine vs coarse pitch, Im still confuzzled on that. I am not sure which does what for what in flight, Coarse for take off and power, fine for cruising and economy?  Which works best for speed, which gets you going faster?  eh, all I know is, the bigger the prop and higher the pitch, the more load it produces on the motor.  

On my Kadet LT40, I had wrecked it on a landing where a cross wind caught the wing and flippped it. My bad, was coming in too slow.  ANyhow, I had busted the motor ount and could not find a replacement SIG one, but had a Magnum 52, same size as the OS that was on it, and it was on a SIG mount. I put it on the Kadet after I repaired it, and got it running and the servo trimmed for it. Tuned it and flew it and noticed it wasn't flying as well as with the OS, it seemed a little slow. I landed it and was looking through my props for a 12x6, I thought I had an 11x7 on it, all I found was my wood 12x8 and an 11x7. I grabbed the props, went to the plane and discovered I forgot to swap out the prop from the other plane, it was a 12x6.  I put the 11x7 on and took off and bingo, flying like it did with the OS.  Larger prop, lower pitch = slower flight, smaller prop, higher pitch= faster flight.  <- see confused.




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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/5/2012 1:15 AM   
vertical grimmace



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Status: offline 		Think of pitch like the gears in your car. The more pitch the higher the top speed. Not good to take off from a red light in 5th gear though. I do not like high pitch. No more than 8 for me generally. It makes it tough to slow down for landing. I find it best to hang in a 6-8 pitch and then load the engine with diameter from there.
It has been established which props this engine likes. 17-6 thrust or 16-8 for speed.
Diameter is considerably more efficient thrust than pitch.

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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/5/2012 1:42 AM   
acdii


 

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Status: offline 		OK makes sense now.  That explains why the 16x8 flew the 4* better than the 17x8.  a 17x6 may have done a better job, but I was satisfied with the APC 16x8 I was using.


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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/5/2012 2:30 AM   
ahicks


 

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quote:

ORIGINAL: ahicks

Ernie - nothing as far as performance, a little different, maybe muted slightly, exhaust note. That's me though, and nothing very scientific for a test one vs. the other.

microdon2 - switch to that 3 bladed prop at the field while 2 blade performance is still fresh in your head. Betting you won't leave the 3 blade on for long. Looks cool, but you take a big performance hit...


microdon - I wrote this in a hurry, addressed this note to you when it was meant for acdii. Apologize for any confusion.

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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/5/2012 2:40 AM   
ahicks


 

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quote:

ORIGINAL: vertical grimmace

Think of pitch like the gears in your car. The more pitch the higher the top speed. Not good to take off from a red light in 5th gear though. I do not like high pitch. No more than 8 for me generally. It makes it tough to slow down for landing. I find it best to hang in a 6-8 pitch and then load the engine with diameter from there.
It has been established which props this engine likes. 17-6 thrust or 16-8 for speed.
Diameter is considerably more efficient thrust than pitch.


Nicely said, I agree. Higher pitch props are also pretty good at blowing control surfaces off 3D types. Not much upside to running over 8" of pitch on those.


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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/5/2012 3:07 AM   
acdii


 

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Status: offline 		I have a 17x4 APC marked as a 3D prop. so that makes more sense now.


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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/5/2012 4:56 AM   
microdon2


 

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Status: offline 		Yes, for 3D planes you want wider props with lower pitch, which produce more torque at lower RPM's.

Vertical Grimmace - when you say "Diameter is considerably more efficient thrust than pitch" doesn't that depend on what you want to do? If you want to go fast you choose one gear ratio (as you said). If you want to pull the plane \ car off the line fast you choose a completely different gear. Not sure how you're saying one "gear" is more efficient than another - they're doing very different jobs, and each has their max-torque-pull RPM range. Would you not agree?

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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/5/2012 5:58 AM   
Ernie Misner



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Status: offline 		Heey, how about that 17x4W APC for 3D profile planes and the 20cc? If indeed that's what it is a W (wide) prop it should be enough load for 3D it seems.

Thanks,

Ernie

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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/5/2012 1:42 PM   
ahicks


 

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Status: offline 		Ernie I think a 20cc would overwhelm that 17x4w. It might work better on a smaller engine? I tached my well broken in DLE at 8700 on an APC 17x6 the other day. Going with less pitch would let the engine rev way too high. What might work better would be if they had something like an 18x4w - assuming you had the prop clearance? 30cc engines love some of those larger (18") "W" series props though...

There's a ton of science regarding props - but there's as much or more trial and error as well? The rules regarding finding more speed differ from those looking for more thrust. Thrust generally does favor "the more the merrier" when it comes to diameter. Consider the size of the props used on an indoor free flight plane (sticks and that clear film?) as an extreme. When it comes to speed though, all that diameter might be viewed as unnecessary drag? Props are just like many other things when it comes to aviation - they're almost always a compromise. -Al

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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/5/2012 5:34 PM   
Ernie Misner



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Status: offline 		Thanks Al. The reason I still might try that 17x4W is that the Wide type APC props load an engine way more that the same diameter and pitch APC in a standard prop. At least with my glow experience so far. My OS 55AX looses about 1,500 rpms when going from a 13x4 to a 13x4W APC. Still, it couldl be under propped like you suggested and that wouldn't be good.

Ernie

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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/5/2012 7:28 PM   
vertical grimmace



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quote:

ORIGINAL: microdon2

Yes, for 3D planes you want wider props with lower pitch, which produce more torque at lower RPM's.

Vertical Grimmace - when you say ''Diameter is considerably more efficient thrust than pitch'' doesn't that depend on what you want to do? If you want to go fast you choose one gear ratio (as you said). If you want to pull the plane \ car off the line fast you choose a completely different gear. Not sure how you're saying one ''gear'' is more efficient than another - they're doing very different jobs, and each has their max-torque-pull RPM range. Would you not agree?

Since we do not have constant speed prop options, we have to settle on a happy medium on prop selection. High pitch props are tough to land without killing the engines. Ask any Pylon racer. It is about compromise.
If you look into the aerodynamics, If I remember right, diameter is 4 time more efficient than pitch. Of course you need pitch. Unless your racing, not as much as most think.

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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/5/2012 11:25 PM   
SigMan



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Status: offline 		i would like to see a comparison review of the DLE 20cc and the XYZ 20cc engines. im sitting here looking at my new XYZ 20 getting ready to go into my new GP Revolver. looks awesome. will be late winter, early spring B4 i get it together and ready to go. sadly.

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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/6/2012 12:57 AM   
Ernie Misner



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Status: offline 		Hey Sig man, there's a thread I started under gas engines about the xyz 20cc, looking for information. That might be a good place to tell us a little something like where you bought it, how much, what they told you about it in comparison to the DLE 20cc, etc.

Would be much appreciated.

Thanks loads,

Ernie Misner

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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/6/2012 1:45 PM   
SigMan



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Status: offline 		thanks Ernie. i'll try that.

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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/7/2012 1:18 AM   
acdii


 

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Status: offline 		Ahicks, good call on the shaft moving.  I tore the DLE down today, and after getting the back cover and cylinder off, I spun the shaft and thats where I felt the resistance. The hub was stuck on tight, had to pry it off, which was difficult since I didn't want to mar up the case, but finally got it off. I then put the case in the vise, so the shaft was hanging down, and the vise supporting the case, and gave a couple whacks with a brass drift and dead blow hammer and the resistance was gone. Turned smoothly.  I put the engine back together, and then discovered I couldn't turn the crank, the rod pin was hitting the back cover.

I took it all apart again and this time removed the key and drove the shaft out of the case, cleaned everything up and then reassembled the engine again, this time everything went back together smoothly and spins nice and smooth.

Replaced the fuel nipple with some brass tubing. Soldered up some 1/8 tubing inside some 5/32 tubing, put a bulb of solder on the end for the fuel line, gave it as close to a 90* bend that I could so the throttle arm clears, and pressed it into the carb with some lock sealer that I had that is used for locking a seal ring onto crank pulleys, its like red locktite but thicker.

And then I tore into the ignition module. The high voltage lead had been pulled out of the case, so I took my dremel and ground out the epoxy so that I could get to the connection for the center lead, stuck the cable back in, soldered it in place, then soldered the ground of the cable to the case, and sealed it up with 5 minute epoxy. 

Now I need to put a test stand together and see if the engine kicks over and runs. The only thing I still need is a new fiber arm for the throttle.


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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/7/2012 1:33 AM   
rcguy59



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Status: online 		Sounds like you're on a roll. A new throttle arm can be made from a large servo horn. I've made several that way.


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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/7/2012 2:31 AM   
acdii


 

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Status: offline 		Thanks, I'll give it a try, I have a few laying around from the Hitec servos I got for the 4* that I am not using.


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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/7/2012 7:42 AM   
Ernie Misner



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Status: offline 		Wow, good progress acdii. Even with all you did with your crank and bearings it seems easier than the motorcycle 2-strokes where the 2 crank halves were pressed onto each side of the crank pin. Then you'd have to use a brass hammer and dial guage to whack the two crank halves straigt with each other. The Yamaha 100cc twin used a "labrinth" seal in the crankcase between the two crankshaft halves. The labrinth seal was aluminum and not rubber, so no drag. Anyone ever seen one?

Ernie Misner

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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/7/2012 1:34 PM   
ahicks


 

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Status: offline 		Re: labrinth seal yes, familiar with them. They used those on some early ('70's vintage) snowmobile twins as well. Kawasaki maybe? Holy cow, that was a looong time ago... 100cc Yami was from that same era too?

acdii - that's good news! Nice to hear you at least tried to be "creative" regarding the ign. module too. Hope that goes as well, best of luck!

-Al

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RE: NEW DLE 20cc Gasser! (Data & Links 1st Post) - 10/8/2012 6:08 PM   
Ernie Misner



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Status: offline 		Yes, the labrinth seals on the old Yami twin was from the late 60's. Guess no one uses them any more?

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