RCU Forums - AP vs NV

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I just thought I'd share a few of my observations comparing the AP .061 and the Norvel AME (pre Revlite) .061. I've had the Norvel NIB for several years now, and just picked up an AP. Just in case anyone cares (probably been beaten to death already somewheres).

First off, it's painfully obvious that the AP is a clone of the NV...no surprise there. I wouldn't want to swear to it, but it appears that most parts would be interchangeable. The BIG surprise is that in several respects, the AP seems superior. Of course, in many others, it falls short. Here's a rundown....

The AP's crankcase casting is much crisper and appears to be of better quality to the naked eye. I can't do a metallurgical comparison though.

The AP's carb bolts on, a distinct improvement IMO.

The AP's muffler is a much tighter fit, although it still relies on that goofy wire-clippy system I loathe - bolts would be so much nicer.

The AP's wrist pin is secured with a wire retainer instead of being crimped in - seems like a nicer system to me.

The AP's prop washer is of the expansion type rather than keyed with a flat - I like that better.

The mating surfaces on the AP's crankcase have NOT been machined - definitely a bad point. Although the casting is quite smooth, there definitely seems to be a potential for leakage there. I figure spending some time lapping the surfaces will be time well spent.

The AP's crankshaft follows bigger engine practices. Instead of having a screw going into the shaft, the shaft is threaded and the spinner is contoured rather nicely. I like AP's method better, although dorking it in may mean replacing the entire shaft instead of just a screw.

The AP's cylinder gasket is clear plastic instead of fiber. Seems like the fiber would do a better job of sealing.

The transfer ports in the AP's cylinder are somewhat unevenly drilled. The NV has ports an even distance up the wall. The AP may benefit from a little port modification (dunno what that might cause in regards to the plating, though).

No mesh screen in the AP's carb inlet. Gotta keep the eyes peeled for crud getting sucked/stuffed in there. On the other hand, the fact that the NV's carb doesn't come off makes it a bit more difficult to clean...seems like the clip retaining the screen in the NV could be problematic to remove without borking the mesh.

The AP carb's barrel action seems just a smidgeon sloppier than the NV, although that's hard to gauge perfectly. The AP's needle valve turns much easier though, could be easier to knock it out of adjustment or have it wander.

The screws holding everything together on the AP are of much softer material, although both use standard slotted heads. I plan to replace 'em with hex head screws.

The NV's crankshaft runs in the same aluminum the case is casted from, whereas the AP appears to have a copper bushing. It looks a tad too red to be brass. Not sure which is the better system there.

Perhaps worst of all, brand new the AP felt a little gritty when I turned it over. Upon disassembly I found that it appears to have residue left in it from machining. The NV was smooth and lightly oiled from the get-go. Definitely want to do a tear-down and clean-and-lube a new AP before ya run it!

I haven't run either one yet, and I don't plan to run the NV anyway - probably going to keep that as-new since they don't make 'em any more. Looks like I won't be able to give a break-in and run comparison for youse guys. I suspect that from my observations, the AP might not be quite as consistent or powerful as the NV...the crankcase leakage could very well be an issue without putting some elbow grease into lapping the crankcase surfaces that should've been machined.

There you have it...my two cents (my opinion and a buck will get you a cup of coffee). If you've heard all this before, well....I didn't have nuffin' else to do and I needed a break from CAD (I'm modeling the AP in CAD at the moment, renders to follow sometime soon).

You forgot to mention the availability of AP versus Norvel, since Norvel is no longer in business.

NorfolkSouthern

Who said Norvel is not in business anymore? SIG has not said that yet as far as I know. I know it's been a long time since they have received any engines but I don't think we should write them off just yet.

Later,
Tim

Sig is selling the AX .40 on their site. I don't know if that means they have them in stock or not.

One characteristic of APs that d_t did not cover is inconsistency (QC). Clearly there is quite a bit of variation from engine to engine. I, too, removed the backplate of my AP Wasp before turning it over and found no traces of metal particles or grittiness. My needle valve assembly was good and snug with less play than the one on my AME .061. I like the well defined click of the ratchet; I can't see how my needle valve could wander. When you remember to attach the glow clip [X(] and richen it a couple of clicks it starts easier than any Cox I own. Mine is still not broken in and I flew it pretty rich today. Near the end of the last flight I could hear it starting to settle in a bit more. Two or three more tankfuls and it should be there. It does not produce the power of my AME - no surprise there - but it definitely pulled my 16oz Sun Fli IV right out of my hand without swooping like underpowered hand launched planes do. It costs $40 brand new and is readily available. I'm really surprised more 1/2A flyers aren't using them (unless they already have a good stock of Norvels on hand). It's not a Norvel. No question there. It is a really good throttled .061 that runs very reliably and is user friendly. It's a sport engine. I'd buy another one without a thought.

Hard to judge QC with just one example. I'd guess my main concern would be the mating surfaces between the backplate, cylinder, and crankcase. The fact that they're not machined (just cast really nice) makes me wonder about the potential for seepage. Shouldn't be hard at all to refine 'em with a little lapping.

The revlite versions use a bolt on carb. That AP crank is what makes it a bad choice for me. I crash alot.
I have to true up the sealing surfaces on the Norvels anyway for my application, So the AP is ok on that one.
I plan on porting one of the AP's to see if I can get one to sing like the Norvels I use in racing. I hope the plating is better in the AP than the pre-revlite versions of Norvel engines. I slagged too many of those. The Revlites though, Hang right in there for me at High rpms. I hope I can get an AP to run with my Norvels, so I can continue to race the non brg 1/2a class. Norvels are just to hard to find now days.

Toad, it would be interesting to see what you can do with an AP. Mine's not broken in but it's a solid 2K behind my AME, maybe a bit more. The only thing I don't like about my AME is the loose nv assembly. Is there an easy fix for this?

I use the needle assembly from the VA engines. I think Larry still has some.
Here are a few pics of what I do to the norvels, A similar thing is about to happen to my lowly AP
www.toadsrc.com/engines.htm

As promised, here's some renderings of the AP .061 I modeled in TurboCAD. Took the measurements using digital calipers accurate to half a thousandth. Model is accurate inside and out with all parts modeled.

Very impressive!!! Do you have a cad 3-view available that I can use when drawing up my plans?

I'm working on a set of 2-D views. Will share 'em when I'm done. Good news! ptu;mer has offered to host the 3-D cad file on his website!

Digital_Trucker;

I remember seeing the AP Wasp in the magazines and for sale before I seen the Norvel engines. Is it possible the AP were issued first, then the Norvels followed them?

Remby. I'm not 100% certain, but I believe the Norvel came firstester.

Seems I didn't quite get the carb right...here it is fixed. Also, here's a jpeg of 6-views. Now if I could just figure out a way to share a USEFUL 6-view image....

Well, this is far from ideal, but it's a better render and has a size box on it...still working on a good solution.

hmmm......that's not the same size as the one I uploaded....?

I finally did it! Here's a PDF! Be sure to set the scaling to 'none' and use black and white only for best printing results. Enjoy!

http://webpages.charter.net/digital_...AP061paper.pdf

Thanks, d_t! That one vectorized much better. Now I have a cad Wasp to use in plans.

Vectorized cad Wasp (screenshot):

btw, I rendered it with a Galbreath head :D