RE: Norvel Engine FAQ

RE: Norvel Engine FAQ
View related threads: (in this forum | in all forums)

Logged in as Guest

Users viewing this topic: none

Printable Version

All Forums >> RC Airplanes >> "1/2 A" & "1/8 A" airplanes >> RE: Norvel Engine FAQ Page: << < prev 1 [2] 3 4 5 6 7 8 9 10 next > >>

Login

Message

<< Older Topic Newer Topic >>

RE: Norvel Engine FAQ - 1/12/2006 12:45:06 PM

Larry Driskill

Posts: 715
Joined: 6/2/2003
From: Lubbock, TX, USA
Status: offline

quote:

ORIGINAL: ptulmer

Well, I can tell a story about two of our friends. Flyswatter had an AME that wasn't turning up like it should and the case would get REALLY hot. He spoke to our own infamous Larry Driskill, and shipped him the engine. My grapevine understanding is that Larry chucked it up in his lathe and took some material out of the center of the crank using sandpaper. That bad boy turns UP now! Maybe since I've prodded their memories, one of 'em can give us details or correct me. I don't know how common this is, but it seems to me the same thing could be accomplished with a drill press if you are very, very, very careful?

Infamous? Infamous? Wow, except for the fact that good old ptulmer had seemed like such a good a good guy and positive contributor here, his throwing out identifiers like "infamous" rather than "clever, sought by the babes, and talented too" would make me think he might really be the corpulent attack dog Ted Kennedy using an alias.

When we started using AMEs they would often seem to go lean soon after launch. But when you picked up the plane (after the engine died from the seemingly over lean condition) the bladder fed needle would still be putting out fuel at the normal rate. But the engine would be very hot - just like you would expect from a lean run.

After it cooled you could fire it up and the needle setting would seem fine, even though you had not changed the needle. Launch again and you would again get the few good seconds of run and then . . . lean again.

In spite of "clever, sought by the babes, and talented too", I was slow to solve the problem. The engines usually got better after a whole bunch of tries and flights, if you stuck with it. Then I realized that the engines were overheating from the bottom end vice from being too lean. The shafts were fitted too tight in the crankcases and when the engine began to warm up the clearance decreased and friction increased causing more heating and it was all downhill until the shaft seized in the case. I finally figured it out when I checked out a shaft and found aluminum on it where it had galled in the case.

I cleaned off the aluminum, lapped the shaft in the case with Bon Ami and oil and viola! Problem solved.

The next step was to put a shaft in the lathe and use emery cloth, followed by 400, 800, and 1200 wet / dry paper with oil to remove a tiny amount of material from the center portion of the shaft. The surface of the shaft behind the port opening and the front 3/16" was left alone. This reduced drag between the case and shaft, but left the front and rear bearing surfaces untouched.

And so . . . especially with plain bearing engines, it may well be that a careful fitting followed by an equally careful bench break-in to the point where you are sure the engine will hold a good, top end needle without overheating and stalling is good practice and will help prevent unwanted dead stick landings. If the engine does not hold a setting on the bench, it probably will not be any better in the air.

Burma Shave

_____________________________

Larry Driskill
Kitting It Together

(in reply to ptulmer)

Post #: 26

RE: Norvel Engine FAQ - 1/12/2006 2:01:33 PM

gcb

Posts: 2422
Joined: 10/24/2002
From: Port Ewen, NY, USA
Status: offline

Viola?

Several years ago some folks (including George Aldrich) were talking about mixing tops and bottoms between the AME .049 and .061 to get a 'tweener size that would still be 1/2A, yet have a little more displacement and performance.

Anyone ever try this?

George

(in reply to Larry Driskill)

Post #: 27

RE: Norvel Engine FAQ - 1/12/2006 3:13:24 PM

Larry Driskill

Posts: 715
Joined: 6/2/2003
From: Lubbock, TX, USA
Status: offline

I built some AMEs using .049 piston/sleeves with .061 cranks. The .049 are really (were ?) about .0477s (bore .400 and stroke .38). The .061 crank (stroke .39) stroked them, but not so much that they were larger than the legal .0504 limit.

< Message edited by Larry Driskill -- 1/12/2006 3:27:04 PM >

_____________________________

Larry Driskill
Kitting It Together

(in reply to gcb)

Post #: 28

RE: Norvel Engine FAQ - 1/13/2006 5:21:41 PM

rtc_71

Posts: 14
Joined: 4/10/2005
From: Springfield, MO, USA
Status: offline

whats a good prop for a norvel .061?

(in reply to Larry Driskill)

Post #: 29

RE: Norvel Engine FAQ - 1/13/2006 5:41:39 PM

Andrew

Posts: 1949
Joined: 2/4/2003
From: Murray, KY,
Status: offline

quote:

ORIGINAL: Larry Driskill

<snip>.......would make me think he (ptulmer) might really be the corpulent attack dog Ted Kennedy using an alias.

Larry --

Need I remind you that RCU has a stated policy against such posts.

Please resist the urge to curse, flame, degrade, insult or embarrass someone in your post. We encourage the free flow of your ideas, but believe that they can be communicated (and received) much more effectively if you keep things civil. If you have to vent, take it offline. We carefully monitor posts and will ban individuals who engage in offensive conduct within the forums. Thanks.

< Message edited by Andrew -- 1/14/2006 3:42:46 AM >

_____________________________

the "other" andrew
I'm not older than dirt, but I can remember when it was patent pending

(in reply to Larry Driskill)

Post #: 30

RE: Norvel Engine FAQ - 1/14/2006 2:58:03 AM

Larry Driskill

Posts: 715
Joined: 6/2/2003
From: Lubbock, TX, USA
Status: offline

quote:

ORIGINAL: rtc_71

whats a good prop for a norvel .061?

Depends a bit on: the plane, the fuel, the altitude, the particular engine, the weather and so on.

To go fast you need some pitch, maybe 3.5 or 4. But you still need RPM so you will not be able to use much diameter. So on a lightweight plane - maybe a 4.5X4 and increase / decrease the dia and pitch from there to optimize.

For "pulling power", more diameter and less pitch. Maybe a 6X2 or 6X3 to start.

_____________________________

Larry Driskill
Kitting It Together

(in reply to rtc_71)

Post #: 31

RE: Norvel Engine FAQ - 1/14/2006 3:00:37 AM

Larry Driskill

Posts: 715
Joined: 6/2/2003
From: Lubbock, TX, USA
Status: offline

quote:

ORIGINAL: Andrew

quote:

ORIGINAL: Larry Driskill

<snip>.......would make me think he (ptulmer) might really be the corpulent attack dog Ted Kennedy using an alias.

Larry --

Need I remind you that RCU has a stated policy against such posts.

Please resist the urge to curse, flame, degrade, insult or embarrass someone in your post. We encourage the free flow of your ideas, but believe that they can be communicated (and received) much more effectively if you keep things civil. If you have to vent, take it offline. We carefully monitor posts and will ban individuals who engage in offensive conduct within the forums. Thanks.

Andrew you are correct. I've transgressed and I apologize to canines everywhere for the association I made.

_____________________________

Larry Driskill
Kitting It Together

(in reply to Andrew)

Post #: 32

RE: Norvel Engine FAQ - 1/14/2006 3:23:34 AM

Andrew

Posts: 1949
Joined: 2/4/2003
From: Murray, KY,
Status: offline

ROTFLMAO

_____________________________

the "other" andrew
I'm not older than dirt, but I can remember when it was patent pending

(in reply to Larry Driskill)

Post #: 33

RE: Norvel Engine FAQ - 1/15/2006 1:55:44 PM

rtc_71

Posts: 14
Joined: 4/10/2005
From: Springfield, MO, USA
Status: offline

thanks larry big help

(in reply to Larry Driskill)

Post #: 34

RE: Norvel Engine FAQ - 1/15/2006 4:16:02 PM

Larry Driskill

Posts: 715
Joined: 6/2/2003
From: Lubbock, TX, USA
Status: offline

I am pretty sure I have posted this somewhere before, but would have been sometime ago. It is from my "Tips for the VA MKII", but most will apply to the Norvels too.

The abridged version would say: Buy clean fuel -Keep it clean; use enough nitro to help keep the needle setting broad (15-30%); use all castor for the oiling duty (20-22%) or at the very least 1/2 castor; to make their best power, these engines need to wind up tighter than the Coxes - don't over prop; make sure you have a good starting battery that will glow the plug element a bright orange; be really careful using an electric starter or you will break something.

"1/2a flying is great fun. In no other engine class do you stand to get so much airborne time for so few bucks. No other class of gas powered model is as likely to bounce rather than break when the ground smites the aircraft. However, when compared to larger equipment, 1/2a engines and planes are more subject to the whims of the weather and nature and less forgiving of inappropriate technique. Clean fuel, hot starting batteries (with the Nelson plug 1.5 volts is nice), fresh glow plugs, and attention to detail are rewarded.
As with many ABC engines, most VA MKIIs may seem ready to go after only one or two runs. However, do the new engine a favor by putting half a dozen two minute ground runs on the engine before launching off into the clear blue. Needle settings for these runs should be just on the rich side of peak RPM and with a small prop. Avoid sloppy rich runs will not allow the engine to heat up properly and put extra stress on the rod and crank. I use a black Grish 5x3 propeller cut to 4" and fuel with 20% castor oil and 30% nitro for break-in. For better front end lubrication, and easier starting put a drop of light oil just behind the prop drive washer before you start flipping. This is especially important on a new engine and is also a good practice for the first flight of the day even after the engine is broken-in.
Proper head clearance is magic when consistency is the issue. The engine is delivered with .006" to .010" clearance above the piston at TDC. Those numbers have worked well in many situations. However, if you are blowing plugs, the head is probably too close for your fuel / weather condition and an additional head shim may be needed. Start with an additional .002" or .004" shim.
Before installing a new glow plug, smear a small amount of Permatex anti-seize compound (part number - 133a at auto shops) on the plug threads. This will help keep the steel plug from seizing in the aluminum head button. If the plug seizes, the head button will slip and turn under the retaining ring when you attempt to remove the plug. If you can not get the plug out you may have to remove the retaining ring and head button from the engine and hold the button while you remove the plug.
If the engine ever feels as though there is a compression leak, check carefully for leaks around the plug and the head retainer. Light oil or WD-40 will usually bubble if there is a leak. If there is a leak, make sure your plug is a Nelson Standard (no machined cuts on the flats of the hex), or a recently purchased HD, and also tighten the plug. If a black "liquid" shows up in the exhaust oil there is probably a problem. Stop running the engine and investigate. The cause may be a piston that has backed off on the wrist pin carrier.
If you use an electric starter make sure the engine is not flooded or you may bend the rod or break the crank.
Top performance depends on using the proper propeller. When choosing the prop remember that these engines need to turn up higher than older style engine to be in their proper power band. Some 1/2a props of the nylon and plastic cast variety have crooked, out of true hubs. If the spinner / prop bolt is wobbling, true up or discard that prop.
Compared to a .36 or .40, these diminutive fellows use so little fuel that there is little reason to use fuel that may have inadequate or inappropriate oil. Use fuel with 20%, or greater, castor oil. In the VA, castor oil based fuel will make more power and promote durability. The use of fuel with low oil, or only synthetic oil, will most likely result in premature wear of the wrist pin end of the connecting rod. Just because you have had good luck with a particular fuel in your .40 RC engine does not mean that fuel has a appropriate oil content for a plain bearing .049. Keep your fuel clean and tightly capped. I filter mine when I put it in my pitbox fuel can and again as I draw it from the can."

_____________________________

Larry Driskill
Kitting It Together

(in reply to BMatthews)

Post #: 35

RE: Norvel Engine FAQ - 1/15/2006 5:29:50 PM

Andrew

Posts: 1949
Joined: 2/4/2003
From: Murray, KY,
Status: offline

Larry -

Would you or one of the other speed gurus post some comments on changing deck height and how it can impact performance.

_____________________________

the "other" andrew
I'm not older than dirt, but I can remember when it was patent pending

(in reply to Larry Driskill)

Post #: 36

RE: Norvel Engine FAQ - 1/16/2006 9:12:44 PM

AndyW

Posts: 1918
Joined: 1/17/2003
From: Timmins, ON, CANADA
Status: offline

quote:

ORIGINAL: rtc_71

whats a good prop for a norvel .061?

Best prop for any sport 1/2A is still the Cox 6 X 3. Lower rpms but better thrust. For sport applications you really don't need excessive rpm.

Amazingly, I've found that the black "rubber ducky" props perform nearly as well as the greys and as a bonus, nearly never break.

_____________________________

Andy Woitowicz

(in reply to rtc_71)

Post #: 37

RE: Norvel Engine FAQ - 1/16/2006 9:38:33 PM

AndyW

Posts: 1918
Joined: 1/17/2003
From: Timmins, ON, CANADA
Status: offline

quote:

ORIGINAL: D Bronk

ANYBody have any test records ,as to a prop size/rpm etc.I`m especially intrested in theBIG MIG 0.074" at the moment but the 0.049" + 0.061" would be nice to have in here too

Depends on the prop brand. An APC 7 X 3 and a Grish Tornado will not turn the same rpms and performance will not be the same. For sport applications, the best prop that I've found for the Norvel .074 is the Cox 7 X 3 1/2. Like the 6 X 3 on the .049/061, the Cox prop will turn slower but the THRUST will be there,,,, for sport applications.

This does not apply to a "need for speed" although, in a sport plane, the Cox will sometimes out fly some other brands spinning much faster.

Pictured is a collection of 8 X 4 props tested on a dieselized Norvel .074 on the same afternoon on the same plane on the same fuel. The Cox actually turned faster than the APC and also out pulled it, in this case.

The issue, when dieselizing an engine and going one prop size up, is that the up sized prop is built for the rpms (faster) of the next sized up glow engine. As those rpms are much higher, compromises have to be made sacrificing efficiency for just keeping the blades attached to the hub. Cox props take the Clark Y airfoil all the way to the hub. The APC goes VERY symmetrical for nearly a third of the blade. Grossly inefficient,,, but they'll never break. Somehow though, Cox props, despite the "thin" blades near the hub, stay together just fine. I suspect that most props are built with a 3 or 4 to one safety factor, just to keep the lawyers away.

I've taken APC props and carved the blades flat all the way to the hub. The result was a free 500 rpm along with extra thrust and efficiency. I've done the same to Grish Tornados and the result was the same. Recent experiments with the newer Master Airscrew props have given similar results. I disliked the old MA props but the newer ones are much better, particularly the wide blade series.

I DO NOT recommend modifying props in this manner unless you're prepared to take responsibility for doing so. In other words, IF you do it, be careful, as always, and in any case.

Also pictured is a collection of 6 X 3 props. You can see a variance of prop shapes and prop blade area. All of these factors along with the plane you're flying determine the best prop to use. Props are cheap, best to get a pile of them and experiment.

Attachments