Author Topic: carrier engine testing (Read 4264 times)

bill bischoff · « **on:** January 08, 2012, 06:46:46 PM »

ENGINE AND PROP TESTING FOR SPORTSMAN PROFILE CARRIER Bill Bischoff

Recently I tested three different engines, a few different carburetors, and a handful of props to see how they would perform for Sportsman Carrier. I tested these particular engines simply because I already owned them. Also, they all have the same mounting pattern and the same size hole for the carburetor. This made it possible to switch things around easily. Even though some of these engines and carbs are no longer in production, they were all standard hobby shop fare; nothing custom or exotic. All flight testing was done with my 323 sq. in. Hellcat, weighing 36-38 oz. depending on the engine. Fuel was 10% nitro/ 5% castor/ 15% synthetic unless noted otherwise. Static RPM figures were measured using an APC 9x6 prop.

OS 32F, stock 3H carb weight 8.3 oz 15,180 RPM (15,240 RPM, Evolution 9x6 prop)
OS 32F, OS 4BK carb 15,600 RPM
OS 32SX, OS 4BK carb weight 9.5 oz 16,100 RPM (16,500 RPM, Wildcat 30% nitro)
EVOLUTION 36 CL, Evo. carb weight 10.0 oz 15,900 RPM
EVOLUTION 36 CL, OS 4BK carb 15,800 RPM

PROP TESTS
All prop test times were for seven laps from a standing start, per normal Navy Carrier procedures.
Times are in seconds.

OS 32F, 3H carb
APC 8x6 22.50 22.60 22.75
APC 9x6 22.50 22.56 22.59 (different day 22.44 22.57 22.61)
Evolution 9x6 22.85 22.97 23.06
APC 9x7 22.58 22.58 22.76
OS 32F, 4BK carb
APC 9x6 22.29 22.32 22.42

OS 32SX, 4BK carb
APC 8x6 21.71 21.71 21.90
APC 8x7 21.83 21.95 22.01
APC 9x6 21.47 21.74 21.77
APC 9x6.5 21.59 21.77 21.92
APC 9x7 21.64 21.77 22.11

EVOLUTION 36 CL, 4BK carb
APC 8x6 21.71 21.95
APC 8x7 21.82 21.89
APC 9x6 21.21 21.56 21.69
APC 9x6.5 21.38 21.42 21.45
APC 9x7 21.15 21.42 21.56

OBSERVATIONS AND ANALYSIS
I had high hopes for the Evolution carburetor, since it is readily available and inexpensive. It is very similar in appearance to the OS 4BK, and has a slightly larger bore through the barrel, which yielded an extra 100 RPM. The carburetor comes set up for a remote needle valve, but the needle valve assembly can also be installed directly on the carb body. Although there isn't an adjustable idle stop, I found that the carb gave a very usable low end RPM. Unfortunately, the bore may be a bit too big, as I was unable to get off the ground without the engine faltering or quitting. Perhaps the barrel could have been sleeved down to reduce the intake size, but I did not try.

The OS 3H carburetor has a smaller bore than the 4BK, which represented a difference of over 400 rpm on the OS 32F. This also resulted in a speed difference. However, for the sportsman competitor, the 32F with the stock 3H carb is such a good running and reliable setup, there is no need to bother with trying to get a 4BK carb. Although the 32F has been out of production for over 15 years, they are not hard to find at swap meets or online. This is the setup I will continue to use on this Hellcat, and would recommend to anyone looking to get into carrier.

I am currently working on an advanced carrier trainer Hellcat with a slider. On this airplane, I plan to use the Evolution 36 with the OS carb. The Evolution and the OS 32SX are very similar in performance, but the Evolution is available, parts are inexpensive, and quite frankly I want to show that this engine is a viable choice for carrier. Note that mine is actually the CL version. The RC version may be a bit faster, but I don't have one to compare.

As for props, note that all the props tested were fairly close in speed, but the APC 9x6 looks to be the prop of choice. Of all the props tested, it seemed to get off the deck the strongest. Other props may be faster in the air, but are slower off the ground. Some novices may find this easier to deal with. The 8" props make the airplane less "floaty" at idle than the 9" props. Again, this may make it easier for novices to get a landing, as the airplane will stop flying when they want it to. Since there is not a lot of performance difference between props, the novice may want to choose a prop to tailor the flying qualities of the airplane to his personal preference.

Now for the disclaimers. These tests were carried out over several different weekends, but weather conditions were similar. The second set of times for the OS 32F/ APC 9x6 were done to make sure nothing had drastically changed during the course of testing. I make no claims, promises, or guarantees in reference to these performance figures. Your results may vary. I invite questions and comments.

A big thank you goes to Phil Dunlap for his help with these tests. His assistance was invaluable.

Joe Just · « **Reply #1 on:** January 08, 2012, 07:29:15 PM »

Thanks Bill, with your permission I will include aq copy of your findings with the rest of my "Wildcat" semi-ARF/C kits. Valuable info for the newbioe and novice participants I deal with.
Joe

bill bischoff · « **Reply #2 on:** January 08, 2012, 08:24:50 PM »

Email sent.

Balsa Butcher · « **Reply #3 on:** January 08, 2012, 11:12:10 PM »

Nice job shaving the Evo down to fight'n size. Thanks for the info, always wanted to do that but know it takes a lot of time. Article for the NCS newsletter maybe?

Wayne J. Buran · « **Reply #4 on:** January 09, 2012, 05:27:40 AM »

Bill, thanks a lot for the information. It was very timely and a lot of work.
Wayne

bill bischoff · « **Reply #5 on:** January 09, 2012, 06:47:51 AM »

Quote from: Pete Cunha on January 08, 2012, 11:12:10 PM

Nice job shaving the Evo down to fight'n size. Thanks for the info, always wanted to do that but know it takes a lot of time. Article for the NCS newsletter maybe?

You noticed! It only took off 5 grams, but IMO it was 5 grams of pure ugly. I already sent a copy to Ted Kraver for the NCS.

john e. holliday · « **Reply #6 on:** January 09, 2012, 08:19:14 AM »

Thanks for all the info.

Bob Reeves · « **Reply #7 on:** January 09, 2012, 10:10:16 AM »

Would sure be more inclined to buy an Evo if it looked like that out of the box, good job...

Joe Just · « **Reply #8 on:** January 09, 2012, 01:35:07 PM »

I personally like the looks of the E engine. I have two. They remind me of one of my very first engines, the Thor .29. the Thor was a real dog, but I had a lot of fun just running it in the basement of our home until the fumes got to me and my folks upstairs. In retrospect, it's a wonder they lived as long as they did with me around messing around.
Joe

Mike Greb · « **Reply #9 on:** January 09, 2012, 04:13:46 PM »

Joe beat me to it, I kind of like the Thor look.

john vlna · « **Reply #10 on:** January 09, 2012, 06:43:49 PM »

Bill,
Very good info. wish I would have had something like it when I started out in carrier 20+ years ago. My hats off to you.

Joe,

Wasn't the Thor an ingnition engine? I think I had one in the 50's, but it might have been a different motor. We tried to make it run as a glow but no luck.

John

Douglas Ames · « **Reply #11 on:** January 09, 2012, 10:48:33 PM »

Quote from: bill bischoff on January 09, 2012, 06:47:51 AM

You noticed! It only took off 5 grams, but IMO it was 5 grams of pure ugly. I already sent a copy to Ted Kraver for the NCS.

Excellent post, very informative. Was the Evo shaved with a vertical mill and turntable? Head turned separate?

bill bischoff · « **Reply #12 on:** January 10, 2012, 07:30:59 AM »

The head was modified on the disc sander first, then the case was hand filed to match. Definitely not precision work. I'm surprised by attention this is getting. Anybody could do it in about 10 minutes.

Joe Just · « **Reply #13 on:** January 10, 2012, 09:23:58 AM »

Joe,

Wasn't the Thor an ingnition engine? I think I had one in the 50's, but it might have been a different motor. We tried to make it run as a glow but no luck.

John
[/quote]

John, time line aout late 1949 early 1950. I bought the Thor for $2 from a fellow club member. It was a glow version when I got it. It would only run if I hit it backards. It would run for maby 5 or 6 seconds and then start running the regular way (counter clock wize). It simply would not start if the prop were flipped CCW, only Clockwize. It had an attached tank with a really neat spring loaded filler valvue. Sure wish I had kept it, but it simply dissapeard arouind 1954 or so. Sob! (as in sob story not the usual s.o.b. as it was sometimes called by my dad)
Joe

john vlna · « **Reply #14 on:** January 10, 2012, 04:11:27 PM »

Joe,
They were originally ignition, mine had a glow plug too, but never ran well. I traded an OK cub .049 for it, bad deal.

bill bischoff · « **Reply #15 on:** March 25, 2012, 08:18:24 PM »

Here's a bit of follow up info. The new Hellcat is done and flying. I first flew it with the EVO 36. To my disappointment, I could never get the idle adjusted properly. It was always lean at low idle, then progressed to too rich above idle. I tried two different carbs, the OS4BK and OS 3H. Both are excellent carbs, and as those who are familiar with them know, their idle metering circuits are of different designs. When both of them gave the same results, I felt more confident that the problem was with the engine itself.

Today I flew the airplane with the OS 32SX and 4BK carb, and it performed beautifully, so this engine will stay on the airplane, unless my recently acquired Irvine 36 works better. More on that to come...

I don't know why the EVO didn't work out. Mine is actually the CL version without the boost port in the liner, so perhaps this has something to do with it. If I get the opportunity to borrow an EVO 36 RC version, I will try it, but until that happens, I guess I'm done with the EVO for carrier.

Wayne J. Buran · « **Reply #16 on:** March 26, 2012, 05:00:24 AM »

Bill, let us know what you think of the Irvine. I do use the Irvine 36 and found it to be more reliable than the pilot. I use the OS 4BK carb in the Irvine.
Thanks
Wayne

Joe Just · « **Reply #17 on:** March 26, 2012, 09:19:17 AM »

I'm using the stock carb on my Irving .36 and had one of the higher top speeds at Brodak's. Perhaps the reason is that I use muffler pressure on both my Irving and on my Evolujtion .36's, the CL version and the R/C version. Sombody here on SH has noted that modern engines are designed to run with muffler pressure. Any facts about that? Anyone that knows me will agree that at 75 I am no competition in anything modeling, but I would say that I use muffler pressure with about 80% of all my planes and find it makes things easier to deal with. I also mainly use plastic tanks with only two tubes, one to the engine and one to the muffler. I removed the fuel line from the engine to fill the plane and replace it back on. Simple set up, and works well for me.

dankar · « **Reply #18 on:** March 26, 2012, 11:09:07 AM »

Keep it simple works for me.
Dan

skyshark58 · « **Reply #19 on:** March 26, 2012, 11:17:26 AM »

Joe, that is exactly why I allowed muffler pressure to be used in NW Sport 40 Carrier. It makes the engine much more user friendly and I think should be allowed is AMA Profile too for the same reason. However the use of mufflers may be a moot point with the advances is the electrics. Mike

Douglas Ames · « **Reply #20 on:** March 29, 2012, 02:56:45 PM »

Quote from: Bob Reeves on January 09, 2012, 10:10:16 AM

Would sure be more inclined to buy an Evo if it looked like that out of the box, good job...

Turntable and a mill and your there! "Machinist" is a disipline I'd love to learn.

bill bischoff · « **Reply #21 on:** May 06, 2012, 08:04:32 PM »

Today I finally had the opportunity to do some more engine testing. Joe Just had sent me an RC version of the Evolution 36 to compare to my CL version. Back in March I was not able to get a satisfactory low end and transition out of mine, and I had commented that I wondered if the RC version would act differently. Here's what I found out. First, Joe's RC engine with the boost port in the sleeve was 400-500 rpm slower than my CL engine without the boost port. I certainly did not expect this, and would be willing to attribute it to variations in individual engines more than to the porting differences. Second, my engine worked better today than it did before. I would attribute that to being 90 degrees instead of 60 degrees outside. And third, Joe's RC engine did in fact work better than my CL engine when it came to idle and transition, and based on today's results I would declare it perfectly usable for carrier. Note that all testing was done using an OS 4BK carburetor. It was not my intent or goal to re-evaluate the Evolution carb at this time.

I also had the opportunity to test out my newly acquired OS 35AX. After a brief break in on the stand, I installed the engine in my new(er) Hellcat. Ground rpm on 10% with an APC 9x6 was a rather impressive 16,500. However, I was once again unable to achieve a satisfactory idle and transition with the stock carb, and installed the trusty 4BK carb. I neglected to re-check rpm, but the first high speed clocking was 21.1 sec, and the second, slightly leaner speed was 20.89 sec. I was pleased enough to call it a day at that point.

I bought the 35AX as a used engine, but I think it had never been run. It may even get better with more time on it.
Since this airplane is painted with epoxy paint, I may even try feeding it more nitro, purely as an educational exercise of course!

Balsa Butcher · « **Reply #22 on:** May 06, 2012, 08:37:35 PM »

Thanks for the report Bill. Very interesting. As far as a previous post, I hope the restriction against muffler pressure will be lifted as soon as possible. My belief is that it was never intended to limit muffler pressure but crankcase pressure as was popular in Class I and II Carrier. No one used mufflers when it was passed. Why it is still on the books is a mystery to me. It is not a moot issues as not everyone is planning to switch to electric.

john e. holliday · « **Reply #23 on:** May 07, 2012, 09:23:40 AM »

Has anybody made a proposal to allow muffler pressure on stock RC engines?

don Burke · « **Reply #24 on:** May 07, 2012, 09:36:01 AM »

Muffler pressure and 10% fuel is always local option until a national rules change happens.

bill bischoff · « **Reply #25 on:** December 02, 2012, 07:00:31 PM »

Here's some more engine info to add to the mix. Today was way too windy to fly, but with temperatures in the mid to upper seventies

it was too nice to sit at home, so we bench raced. Mike Greb had just gotten a new OS 35AX on ebay, and I had some things I wanted to try. Mike brought out a Jett 30 size tuned muffler, and I brought several different fuels. Since Mike's 35 was brand new, he was running it on an APC 8x6, with 10% 11/11 fuel, and the stock OS carburetor. With open exhaust, it turned 19,200 rpm. With the Jett muffler, it was actually a bit slower at 19,000 rpm. I suppose this indicates that the muffler is tuned for a lower RPM.

On my 35AX with an OS4BK carb, I did a few test runs with an APC 9x6. On 10% with open exhaust, it turned 16,200 rpm. With the Jett muffler, it turned 16,600 rpm. With no muffler and 50% nitro fuel, it turned 17,100 rpm.

Next, I ran my silver case/ red head Irvine 36 with an OS4D carb. I have just recently gotten around to test flying this engine, and it runs well and is comparable in performance to other engines I have tested. Even though I bought it "used" it seems like it is still breaking in. A few weeks ago, we got a 21.8 high speed on the only flight we timed. Today, on an APC 9x6 and 10%, it tached 15,700 rpm. On the APC 8x6, it jumped up to 19,200 rpm, the same as the OS 35AX.

Once I got home, I looked up Jett's web site and checked some RPM figures. All the engines (25/30/35) that used the 30 size tuned muffler were running between 17,600 to 18,200 rpm, so I would have to suppose that is the rpm range the muffler is tuned for. Since we ran above and below this rpm range, with some more prop experimenting we should be able to hit the sweet spot.

I also noticed that compared to a previous tach reading of 16,500, today my 35AX only turned 16,200. This may be partly due to typical variations encountered from one day to the next, but I think it is more attributable to the differences in carbs. The stock carb I ran previously has more choke area than the 4BK I am currently flying with.

While running Mike's 35AX with the stock carb and the Jett muffler, it seemed like the carb was going to work well enough to be useable, which would be great. My goal is to find a high performance setup that uses off-the-shelf, currently available components, that everybody will have access to. On the next good flying day, I will be trying the 35AX and muffler on my Hellcat with different props (and carbs) to see what kind of qualitative and quantitative results I can achieve.

Jim Oliver · « **Reply #26 on:** December 02, 2012, 09:08:33 PM »

Good stuff--thanks for the work.

Jim

Wayne J. Buran · « **Reply #27 on:** December 03, 2012, 04:58:51 AM »

Bill, thanks for the update on the engine tests. Great help. BTW, can you inform on the differances you see between the 4BK and the 4D OS carbs.
Thanks
Wayne

bill bischoff · « **Reply #28 on:** December 03, 2012, 07:31:38 PM »

The OS 4BK and 4D carburetors are very similar. I believe the only parts they don't have in common are the body and the barrel. In all likelihood the bodies are both made from the same casting. The only difference is the diameter of the neck that fits into the engine. On the 4BK it's .510", and on the 4D it's .530". Something I had forgotten until Gary Hull recently reminded me is that the 4D has a slightly larger bore through the barrel than the 4BK, .305" vs .295".

The 4BK will fit the OS 32F, 32SX, 35AX, Evolution 36, and many other engines. The 4D will fit the ThunderTiger Pro 36 and others. If you have a 4D and need a 4BK, the neck can be turned down a little. If you have a 4BK and need a 4D, K+S fuel tank tinplate is .008" and makes a suitable wrap-around shim.

My Irvine has a big carburetor mounting hole, so it needed a spacer regardless of which carb I used. I had a bigger stash of 4D's, so that's what I installed. Now that I know (again) about the different barrel bores, I will at some point do a back to back test with the two different barrels to see how much difference it makes.

Unfortunately, you can't buy either of these carbs anymore, so what I do is watch ebay for cheap OS engines, just to get carbs. Frequently, rough looking engines with good carbs sell for less than what you'd pay for just a carb!

Wayne J. Buran · « **Reply #29 on:** December 04, 2012, 04:24:52 AM »

Bill, thanks for the info. I have always run the 4BK in my Irvine .36's but needed the delren insert that originally came with the Irvine R/C 36/40 cases. Those carbs are just the thing to make certain engines run a lot better. Now I know the 4D will work although I have enough 4BK's to keep me going for a while.
Thanks
Wayne

Peter Roberts · « **Reply #30 on:** December 08, 2012, 04:11:04 AM »

Great stuff !!.. A really informative post with some useful information. The OS 4BK seems to be the favoured carburetor, does anyone have any experience using Perry carburetors ??. Just wondering how the Perry compares to the OS carby ??

Peter.

Wayne J. Buran · « **Reply #31 on:** December 08, 2012, 04:45:18 AM »

When I first got started with the Irvine .36 I tried a Perry and had no luck. I know that Gary Hull has tried the Perry a lot and always winds up going back to the 4BK. Always much better luck. I also use a 4BK on my K&B 40 with great results. Generally speaking the "O" rings are really what need servicing in the 4BK's and they are still available from OS.
Thanks
Wayne

john e. holliday · « **Reply #32 on:** December 08, 2012, 08:22:00 AM »

Can the O rings be obtained at a good auto supply store???

Wayne J. Buran · « **Reply #33 on:** December 08, 2012, 10:59:23 AM »

Doc, I don't know basically because i dont know much about "O" ring applications and tolerances. The part number for the mixture valve o-ring is OS 24881824 and the part number for needle valve oring is OS 24981837. The whole mixture control valve with o-ring is OS 26781309.
Thanks
Wayne

don Burke · « **Reply #34 on:** December 08, 2012, 11:15:42 AM »

If you have the metric dimensions of the O-ring, OD or ID and ring thickness, McMaster-Carr has a great inventory, and they have very rapid shipping. I usually get things in two days.

Peter Roberts · « **Reply #35 on:** December 08, 2012, 02:54:34 PM »

Wayne, Thanks for that, I think I'll give the Perry carb a miss.

Peter.