My .15 shootout AP OS LA and CV-A  
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My .15 shootout AP OS LA and CV-A - 4/23/2006 7:18:44 PM   
spyder0069


 

Posts: 306
Joined: 1/13/2003
From: Rochelle, IL,
Status: offline 		Recently I got a couple more .15 size planes and ended up buying a couple of engines to test. All tests run with a new A3 plug in each engine, 15% wildcat premium fuel, and master airscrew props. Testing done here in Rochelle, IL at 68 degrees using a Hobbico digital tach. The numbers are the absolute peak rpm.

First up was a well broke in (approximately 1.5 gallons run through) AP .15 modified with the stinger enlarged and the head shim removed.

7x4 17,500
8x3 15,700
8x4 14,400
8x5 13,400

Next inline is a new O.S. LA .15 I bought that has now been through about a half gallon. The inside of the baffle is bored out as large as the supports will allow and the stinger is bored two bit sizes. I did not get tach readings before the mods.

8x3 17,700
8x4 15,800
8x5 14,500

Finally is a new O.S. CV-A .15 I bought that has about 24oz of fuel run through it. Its possible its still breaking in. Initial readings are with the stock muffler.

8x3 18,300
8x4 16,300
8x5 15,000

Then the muffler was bored identical to the LA's muffler.

8x3 18,500
8x4 16,700
8x5 15,600

All engines idle well and transition was good. The CV-A does come out ahead over the LA by 800-1000rpm on every prop. The twin needle carb is also nice and does allow you to tune it for better transition over the LA. The CV-A will hand start with no problems the LA will not, and the AP occasionly will hand start. The baffle on the O.S. engines is extremely restrictive however after boring it there was a noticable increase in loudness which put it almost as loud as my .46 engines. The LA is still a great engine and will still probably be the best cost effective choice for most especially since the cv-a isn't allowed in combat. Not only is it disqualified by price but I think you would be hard pressed to get the engine to turn under the 17,500 rpm limit on the manditory 8x3 prop.

The AP is a very user friendly engine and still runs great lugging the bigger props. Its obviously lower on power but also lower on weight. The CV-A is about one ounce heavier than the LA and the AP is about 1.5oz lighter than the LA. For a small plane where you need to fit the muffler in the cowl and keep the weight down it would be a great choice. Don't expect it to compete with the O.S. engines though.

Dion Brewington


       Post #: 1

RE: My .15 shootout AP OS LA and CV-A - 4/24/2006 2:01:24 AM   
WMB


 

Posts: 750
Joined: 10/5/2002
From: Great Falls, MT, USA
Status: offline 		Great info Dion!
Any idea how they pull a plane around in comparison. I have a Shrike with a Magnum 15. Tried different props and I like the APC 8x4 best sofar. But I would like to get more speed without weight gain. I do have a new in box LA15. But the CV-A sounds like the way to go.
Thanks, MikeB

(in reply to spyder0069)
       Post #: 2

RE: My .15 shootout AP OS LA and CV-A - 4/24/2006 2:34:39 AM   
spyder0069


 

Posts: 306
Joined: 1/13/2003
From: Rochelle, IL,
Status: offline 		I have the O.S. LA .15 on a Hobbypeople AT-6 15-25 size Texan. I bought the LA from tower and before I got it in I started having doubts it would pull this plane so I bought the cv-a as a backup. Bench ran the LA for a couple of tanks and mounted it on the plane. Honestly it pulls it great. Large loops and all. I tried each of these props on this plane and the 8x4 did seem the best. The 8x5 was a little sluggish getting off the ground compared with the 8x4 and the 8x3 made a lot of noise but didn't pull it with the speed I needed to combat our usual 15mph winds that we have here (60 miles west of chicago). All the info I have read on these LA's has turned out to be correct and that being said your magnum should be almost identical (except maybe the weight) to the LA and I would not swap it out for it. The cv-a does appear to live up to its name and price. I did weigh the engines tonight on my digital postal scale so I could give a accurate weight on these. All were weighed with their muffler and included prop nuts.

AP Yellowjacket .15 5.4oz

O.S. LA .15 6.3oz

O.S. CV-A 7.4oz

Right now I am swapping the LA for the CV-A and hope the extra 1000rpm will make up for the extra ounce of weight. I started off in R/C flying electrics 5 years ago so I am stingy with my ounces. It does look like the cv-a will pull the 8x5 on this and should be pretty nice once unloaded in the air. I also have some APC props on the way as they are always more efficient and may bring better performance.

My test does dispell one post here on RCU that stated the LA will swing a bigger prop than the cv-a. The tach numbers show even with the 8x5 the cv-a outperforms. I had considered mounting a 9x4 to try it out but besides not having anything to shim the prop shaft I don't want to burn up a engine trying a prop that you wouldn't use with a .15 anyway.


(in reply to WMB)
       Post #: 3

RE: My .15 shootout AP OS LA and CV-A - 4/29/2006 12:58:34 AM   
buzzard bait


 

Posts: 1015
Joined: 1/1/2003
From: Ithaca, NY, USA
Status: offline 		Dion, I wonder if I can help you hand start your LA. I've not had an LA, but I understand that the insides are very similar to the older FPs. I have a lot of FPs including the .15 and they all became great starters once I realized that they flood easily. I once started my .15 FP at a meet for the first time after pulling the plane out of the attic where it had sat for two years--on the first flip. Here's the method:

Choke and turn the prop to bring the fuel to the carb, then ONE choked flip. Then two or three fast flips unchoked and without the glow starter to get the fuel to the combustion chamber. Then apply glow starter and flip...bzzzzpt!!

Lots of older .15s ran fine on 9x4 props. I've always run my FP on 8 1/2 x 4. Worked great on a 3 lb., 56 in. span Champ. It would easily take off from a rough grass field on that combination.

Jim

< Message edited by buzzard bait -- 4/29/2006 1:00:17 AM >

(in reply to spyder0069)
       Post #: 4

RE: My .15 shootout AP OS LA and CV-A - 4/29/2006 2:01:35 AM   
spyder0069


 

Posts: 306
Joined: 1/13/2003
From: Rochelle, IL,
Status: offline 		Jim,

Thanks for your input. In fact I do need to amend my statement. The LA will flip start with your procedure wearing a glove and using a forward flip. The AP and cv will both hand start just by pinching the spinner and giving them a back flip against the compression just like high compression engines of larger sizes. The LA acts just like the FPs I have had and the larger LA's and will not respond to a back flip. And of course in a bozo moment I once tried to hand flip it without a glove to make sure it wasn't hydro locked and split my finger open on the back of a MA Schmitar prop (geez and I thought the APCs were sharp). The problem with the LA's is that once in a cowl you can't see the fuel line and know if the fuel has pulled up to the carb. AND THEY HYDROLOCK VERY EASILY because of the airbleed carb not having a low speed needle limiting the fuel into the carb at idle/shutdown. So my experience so far is at the end of the day let the engine run at idle and turn in the high speed needle letting the engine run the fuel out of it. This keeps it from having fuel in to rust and during the startup I fuel first with the needle still closed off otherwise the pressure from filling the tank will flood the engine. Then I just reset the needle and can hit it with the starter knowing that the engine isn't flooded and the starter will pull the appropriate fuel up and get the engine running.

Dion

P.S.
The Master Airscrew Schmitar was a dog of a prop. I had better performance from the standard MA or wood and I just got in some apc's to try out. The schmitar was extremely flexable and I don't believe was holding its pitch at the rpms these engines rev.



< Message edited by spyder0069 -- 4/29/2006 2:04:33 AM >

(in reply to buzzard bait)
       Post #: 5

RE: My .15 shootout AP OS LA and CV-A - 4/30/2006 2:47:38 PM   
buzzard bait


 

Posts: 1015
Joined: 1/1/2003
From: Ithaca, NY, USA
Status: offline 		Dion, those Scimitar props look very cool, but I didn't realize they were less efficient. I did discover that an 8x4 Scimitar is actually lighter than the regular MA 8x3, even though the 8x3 looks like it has much less material. That agrees with your observation that the Scimitar is a different material. I'll be trying that prop in place of the Scimitar today (on an old Enya .09).

Yes, I always forward flip (but without a glove--hmmm). Never experienced hydro lock on a glow engine (but I have many times with diesels). Well, on second thought, maybe I have--I do remember getting bit once or twice. I think I've got an unconscious habit now of pulling the prop through to see if it kicks. At any rate, it's been a long time since I've been bit.

The back bounce sounds like a nice method on engines that respond to it. I have an OS .70 now, and I understand the back bounce is the way to hand start them. I won't stick my finger in that one.

Jim

< Message edited by buzzard bait -- 4/30/2006 2:50:17 PM >

(in reply to spyder0069)
       Post #: 6

RE: My .15 shootout AP OS LA and CV-A - 5/5/2008 1:46:43 PM   
AndyW


 

Posts: 1918
Joined: 1/17/2003
From: Timmins, ON, CANADA
Status: online 		In all of these discussions re RPMs, can you give us prop brands, please?

Any comments on the Norvel .15, bearinged or bushed? Good, bad, ugly or???

_____________________________

Andy Woitowicz

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       Post #: 7

RE: My .15 shootout AP OS LA and CV-A - 5/5/2008 3:34:40 PM   
spyder0069


 

Posts: 306
Joined: 1/13/2003
From: Rochelle, IL,
Status: offline 		All my tests were done with master airscrew plastic/composite props. I have flown that AT-6 many times since then and have found the cv-a to be a wonderful powerful engine. My opinion today is if you have a plane you plan to keep for a while then spend the extra money on the cv-a. If you have a plane that will be used for combat or you worried about crashing save some money and get the LA. The LA is a great engine but the cv-a has better snap throttle response, better starting habits, smoother idle, and a crap load of power. You would easily mistake it for a 25 on a plane in everything except maybe extended verticle performance where the 25 will chug the bigger prop. But it would be close. :^)

(in reply to AndyW)
       Post #: 8

RE: My .15 shootout AP OS LA and CV-A - 5/5/2008 3:37:35 PM   
spyder0069


 

Posts: 306
Joined: 1/13/2003
From: Rochelle, IL,
Status: offline 		I have no experience with the norvels in that size. I had plenty of .061/.074 flavors of norvel and they we quality engines with surprising power. I've been out of the loop for the last 8 months or so but last I heard they were out of business. Siig was selling there product for awhile and then parts were really hard to get. I could be wrong.

(in reply to AndyW)
       Post #: 9

RE: My .15 shootout AP OS LA and CV-A - 5/5/2008 7:02:35 PM   
AndyW


 

Posts: 1918
Joined: 1/17/2003
From: Timmins, ON, CANADA
Status: online 		Hi Spyder,

Thanks for your response. In fact, I'm a bit of a fanatic for Norvels as you can see here. http://ca.youtube.com/profile_videos?user=hopeso&p=r The reason I ask is that I bought out a shop's entire Norvel stock two years ago, intending to dieselize them all and put them up for sale as a unique item.

Life and stuff intervened and since then, as you say, Norvel has stopped making engines so my idea has frizzled out. Now I have far too many Norvels and need to sell some. I have 4 BB .15s NIB and several used, bushed and BB.

I was trying to get a handle as to what the desirability of this size might be as these are non RC. I'm checking with the round and round guys now. As it turns out, for some reason, the Norvel .15 isn't as strong as it's exotic nature might suggest. A puzzle since their .06 and .074 are real performers.

But, thanks again.

_____________________________

Andy Woitowicz

(in reply to spyder0069)
       Post #: 10

RE: My .15 shootout AP OS LA and CV-A - 5/5/2008 10:08:43 PM   
jeffie8696



Posts: 1139
Joined: 5/10/2007
From: coralville, IA, USA
Status: offline 		Sig is selling out their last lot of Norvel engines. All .40 size. I was tempted but they are still very expensive and with no parts support a risky propsition. Fox says their .15 BB will turn an 8X4 to 15,000 but they are not specific about it. All my Fox .15s are the older bushing engines and they turn 15s or better .

_____________________________

Castor, its like Vitamin C for glow engines. I am not Dom from Airwolf but I do resemble him.......Unfortunately

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RE: My .15 shootout AP OS LA and CV-A - 5/5/2008 10:17:41 PM   
spyder0069


 

Posts: 306
Joined: 1/13/2003
From: Rochelle, IL,
Status: offline 		If I remember Fox engines are usually quite a bit heavier than most other brands. I have never owned one personally. I know there is a big following for them.

(in reply to jeffie8696)
       Post #: 12

RE: My .15 shootout AP OS LA and CV-A - 5/6/2008 1:58:14 AM   
buzzard bait


 

Posts: 1015
Joined: 1/1/2003
From: Ithaca, NY, USA
Status: offline 		Depends which Fox. My .15 BB is at least 7 1/2 oz with muffler, but my old plain bearing slant plug engine is only 5 oz with muffler.

Jim

(in reply to spyder0069)
       Post #: 13

RE: My .15 shootout AP OS LA and CV-A - 5/6/2008 2:06:47 AM   
jeffie8696



Posts: 1139
Joined: 5/10/2007
From: coralville, IA, USA
Status: offline 		I wouldn't know. I can't find a muffler!!!

_____________________________

Castor, its like Vitamin C for glow engines. I am not Dom from Airwolf but I do resemble him.......Unfortunately

(in reply to buzzard bait)
       Post #: 14

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