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Building Tips and technical articles. => 1/2 A building. => Topic started by: Andrew Tinsley on April 05, 2013, 09:27:08 AM
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Hello All,
If I remember correctly, Larry Renger was one of the first people to say that the AP Wasp had good 1/2A potential. So I bought one and gave it a try. It seemed OK, so I just ran it in as per the rather weird instructions. Put it in a plane and flew it, I used somewhat larger props and didn't run it at maximum bhp revs. I was very pleased with the Wasp and knowing how a good engine will be discontinued as soon as you discover it is good, I purchased half a dozen more. I decided to have a closer look and found the crankshaft fits to be all over the place. One was so bad, I sent it back for a replacement. I then dismantled the engines and checked the other critical areas. The good news was that all the piston / liner sets were beautifully made and were excellent fits. However the rest of the components were a severe disappointment. About the sort of fits and finishes that I would expect to see on current CS manufacture. You may like to toy with what the initials CS stand for perhaps.
Reading the more recent threads on the Wasp, I see Larry has got through four crankcases (was that the reason I sent you four cases Larry?) Kenneth Cook also managed to wear out a loose fitted main bearing bush and he also had other issues with the engine. I do know that Ken does use extremely high revs in his 1/2A combat applications, so maybe that is the cause of the problems.
Up to now, my first Wasp has had a fairly gentle life and has only put in a couple of hours running. The crank does feel more sloppy than I would like. I am just about to put a second Wasp into operation and I am beginning to feel that these engines may not be all that good after all! Which is a great pity as I stocked up with them! Maybe should have spent more and got a couple of Norvels?
What have been peoples experience with the Wasp? Am I just expecting too much from what is a very cheap engine?
Regards,
Andrew.
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I have had 2 APs that had bad crank fits to start with, and as noted wore out 4 more! Shouldn't happen with a bronze bushed engine! Every one ran really well except for the tight one at first. The parts are interchangeable with, at least, the old Norvels and I now have one APvel with the AP top end and crank, Norvel case with venturi. Haven't run it but it feels good.
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Hello Larry,
Thanks for the reply. I suspect you have more control line hours than most, using AP Wasps. Seems that everyone so far has had problems with crank / bearing bushes. These seem to be either pure lousy choice of components on assembly or the bush material is not good when it comes to wear. I know that Ken punished his AP Wasp at very high rpm for 1/2A combat, Have you been running at high rpm too? My first Wasp has been pampered and the main bearing is beginning to show slackness. Your APvel sounds a good way around the bearing problem, but is a rather extreme and expensive solution! Should we not do better by warning people off the AP Wasp and going for Norvel? From recent posts, it sounds as if a bunch of people are looking at a C/L venturi conversion for the Wasp. I think my advice would be to steer clear of the Wasp and buy Norvel. The Norvel fits and finishes are just so much better than those of the Wasp. Seems a shame to say this, especially as I have 7 of the Wasps!
Regards,
Andrew.
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Andrew, I used to try to talk about how cheaply made the wasp was compared to the Norvel, seems every time I mentioned it someone went on about how great the wasp was so I stopped. I have 5 wasps and a bunch of Norvels, the ap's stay on the ground mostly. If you find a deal on one and need it for a trainer the AP was okay. Long live the Norvel!!!
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Thanks for those observations Ray, I am beginning to think that you are correct. Oh well I can always build a few more trainers! At least I have one grandson that is interested and another baby on the way! So trainers are the order of the day.
Thanks,
Andrew.
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Andrew, I wouldn't give up on the engine. For my needs, it just didn't do it for me. I'm willing to accept that but I tried very hard to make it work. Remember, that was the only 1/2A engine available for a while. Norvel's were out of the price range due to demand and no supply. I haven't used mine for stunt like Larry has. My hats off to Larry for making it a viable power plant. I have really thought about doing what Larry just suggested and that's to cross breed it with the Norvel. I did like the piston sleeve fit. I believe you noticed the same in the fits of yours. I feel that if you keep things in the designated rpm range you may just love this little engine. Give it a try and let us know your findings. Ken
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Andrew, I wouldn't give up on the engine. For my needs, it just didn't do it for me. I'm willing to accept that but I tried very hard to make it work. Remember, that was the only 1/2A engine available for a while. Norvel's were out of the price range due to demand and no supply. I haven't used mine for stunt like Larry has. My hats off to Larry for making it a viable power plant. I have really thought about doing what Larry just suggested and that's to cross breed it with the Norvel. I did like the piston sleeve fit. I believe you noticed the same in the fits of yours. I feel that if you keep things in the designated rpm range you may just love this little engine. Give it a try and let us know your findings. Ken
Ken,
You can flog a dead horse all you want but it's still dead. I never bought one . I guess that I've been trained to immediately ignore a knock off. In this case it seems that I saved a few dollars. Did you get my offer of some wing cores?
dennis
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Hello Ken and Dennis,
I have been running a Wasp in a Jim Thomerson Cheap Thrill. The second one is going into a Mirablis. The performance of the Wasp on a stunt plane has been pretty trouble free and it has done exactly what was required of it. It was the fact that the bushing on that first Wasp was getting noticeable slack after around 2 hours running time. It started out as a good fit and went down hill from there!
For what I paid for the Wasp, it has done reasonably well and proved a good stunt engine. I just don't think they wear at all well. I have plenty of them, so I can keep swopping out the worn ones. A Big Mig Norvel is a little more hassle but they seem to go on for ever. The TD 0.049 / 0.051 is nowhere near as nice for stunt and I don't use them for that purpose any more.
I don't know who does the piston / liners, but it certainly isn't the people that do the rest of the engine! I have decent bore gauges and all my P/Ls are spot on and are of very good quality, no problems with wear in that dept. Pity the rest of the engine is not very good. The Apvel concept is a good one, because it uses the best bit of the Wasp.
Regards,
Andrew.
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Disclaimer! I do not have, nor have seen the latest NV engines. My comments are based on the old Norvels.
If I were buying an engine right now, it would be the NV. First, it is now almost the only game in town, as the AP seems to be discontinued. Second, it comes with a CL venturi, so is cheaper than an AP combined with the cost of a now unavailable aftermarket venturi. It is properly equipped right out of the box.
With the Galbreath head, the Mk 1 Brodak is an alternative worth looking at, they run with near TD power and Medallion fuel draw, a great combination. The caveat is that I have little experience with them on a long term life basis. The NV is probably cheaper and likely more reliably proper fits than this combo too.
I still have a couple of NIB APs, and you may be sure the cranks will be well polished before they ever run. Chuck a cut-off bolt into your drill, mount the crank, and run it at low speed. 2000 grit paper with oil followed by Simichrome on a paper towel will provide a mirror finish. I published this recently in the Cox newsletter with photos.
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My comments are based on the older type of Norvel. Like Larry, I don't know what the new ones are like, but they are much more likely to give a good performance and wear well.
So everyone that has been clamouring for the Jan Venturi system, may like to reconsider and go the Norvel route instead. The Wasp still seems to be available on this side of the pond, but I don't think I will be getting any more!
Regards,
Andrew.
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OK, so where do ya find Norvel .061's these days? now that I just bought 2 NIB AP Wasp's
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My suggestion would be to run those engines. My experience wasn't as good as I would've liked it to be. If in the market for a Norvel which is no longer made, the new company is NV engines http://www.nvengines.com/ . You can also reach Alex at klondike17@juno.com. He's very quick to respond to e mail and has been extremely helpful to me. Ken
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In answer to James, most of the APs are fine engines that perform well. Even with stunt use they are driven hard. I figure that I have over 100 runs on the ones that have worn out. That's 8,000,000 revolutions or more.
And I believe that going with more oil will prolong the life farther. I suspect that added oil only degrades fuel consumption, not performance. And may improve performance by reducing friction and carrying away more heat.
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Hey Kenneth and Larry,
Thanks very much, BTW Kenneth, who is Alex? please forgive my obvious ignorance.
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Hello James,
Alex is the chap that does the Norvel engines in the US. Last time I looked he had some of the old C/L engines in stock. Don't get me wrong, the AP Wasp isn't a total disaster and I have been reasonably impressed with it in stunt use. It just doesn't last too long. I have several left so I will make use of them in the end. Just buyer beware , if it sounds very cheap there is usually a good reason!
Don't be downhearted about the fact there isn't a readily available venture for them. The use of a Cox TD venturi and the Texas Timers Kirncraft NVA assemblies, leaves only a simple threaded bush to make and you are away.
Andrew.
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Thanks Andrew.
James
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If I were buying an engine right now, it would be the NV. First, it is now almost the only game in town, as the AP seems to be discontinued.
Another one worth considering is the MP Jet 061BB. I'm sure they're considerably more expensive and also a litttle heavier than an AP or NV, but against that, they're beautifully made, ballraced, and likely to last a long time. What I also like about them is that you don't need to spin a toothpick at 25000 rpm, or use a lot of nitro. With an APC 7x3 and 5-10% nitro, I'm seeing around 17000 rpm from the 061 glow (and have clocked the 061 diesel at 17600 with the same prop), which to my way of thinking is a lot of good useable performance for 1/2A stunt.
Steve
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I have crashed a few planes trying to use the MP glow and diesel engines in stunt. For some reason, they will quite reliably quit at the least opportune time. Agreed, tons of power! Great for RC and FF, not for CL.
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Hey Larry, maybe it needs a different temp. range glow plug???...No clue about diesels though. BTW, Has anyone tried the Big Mig/ NV .074 for stunt? Sounds good in theory huh?---TIA, James
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Hello Larry,
Your experience of the MP Jet 0.061 is a little different to mine. I don't know about the glow versions, but the diesels have been a very reliable power unit for stunt. It has been a good few years back since I used them. They have been out of production for a good few years and now back in production. I never had any real problems. They were a touch critical to set up correctly, but once you had the NV setting about right, they performed very reliably. I found that the ground setting had to be much richer than I would set for just about any other diesel I have used (and that is an awful lot!). Maybe you got caught out by this quirk?,
Off topic but worth mentioning. The little MP Jet side port diesel is an absolute gem! OK no good for steroid stunters but more than worth trying on a small lightweight stunt job that would be fine for a cox reedy. For relaxed 1/2A sports use, it would be difficult to beat.
Andrew.
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Hi All,
So has anyone tried a Big Mig/ NV .074 in 1/2A or "so called" 1cc sized stunt ships? What'd ya think about it?
Later,
James
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James, I used the Big Mig .074 on the Brodak Pathfinder. It flew the plane well but it was waaay fast. Props are just somewhat difficult to find with that engine as it's a size that's in between. I played around with a few props, but I also was using the r/c version. I personally disliked it. It was extremely difficult to start as I had the carb wired wide open. The instructions suggested only to crack it slightly open on startup. I later found the .061 control line venturi fits the .074. I haven't tried the engine, but I bolted the venturi on and it's awaiting another try. I switched the .074 to a .061 on the Pathfinder and I don't even use the engines full power potential as I don't need it. Ken
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James, I used the Big Mig .074 on the Brodak Pathfinder. It flew the plane well but it was waaay fast. Props are just somewhat difficult to find with that engine as it's a size that's in between. I played around with a few props, but I also was using the r/c version. I personally disliked it. It was extremely difficult to start as I had the carb wired wide open. The instructions suggested only to crack it slightly open on startup. I later found the .061 control line venturi fits the .074. I haven't tried the engine, but I bolted the venturi on and it's awaiting another try. I switched the .074 to a .061 on the Pathfinder and I don't even use the engines full power potential as I don't need it. Ken
Ken,
Using the Norvel 074 is overkill as it pulls most models that use an OS10 with no apparent effort. These were a hot set up in upgrading the House of Balsa 1/2A warbird models a few years ago. If you adapt to a Nelson head or turbo head there are significant gains to be had. I really wish that 1/2A was classed the same as Great Britain. It just makes a whole lot of sense to me.
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In So. Cal. We fly 1cc stunt, not 1/2A. .061 max, unless flying a twin, when twin .051s are allowed.
Stan Tyler built a Twin Flite Streak and it flies fantastic ... for as long as he can get both engines to run mw~
A properly set up .049 model is completely competitive in the right hands, but .061s are a lot easier to get running right, and still fly well when not quite on peak.