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Engine basics => Engine set up tips => Topic started by: frank mccune on November 28, 2018, 03:57:43 PM
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Hello All:
I have an OS FP .40 that I have been using as a Diesel on a profile stunt plane. Do I have to do anything to it to get it to perform as well as the La .40 on glow fuel? If so what? I have the blow head for it. All I know about the FP is that it had a third port in the sleeve. The LA engines run very well!
With a DDD head, it ran very well. Perhaps I should run it as a Diesel in OTS in my "new" Vilking. Lol Cleaning the Diesel residue will be a new treat for me. Lol Is it true that one recieves 5 points extra for using a Diesel in OTS? It should be upped to 50 points to intice more "people" to endure the joys of operating a Diesel. Lol
Tia,
Frank McCune
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Just make sure it has a correctly sized venturi and go fly. Should use about 3 1/2 to 4 ounces on a 40 ounce plane.
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I have used FP.40s stock out of the box or fresh from the swap meet table on many airplanes. Just don't run any more than 4 inch pitch, don't over do the venturi, ( .250" or less) and let it breath with as much exhaust as you can. A local guy here, (and I have related this story many, many times,) went from beginner class to a damn good flying expert with a single stock SIG Twister and wore out three OS FP.40s along the way. Years ago John Miller lived here in the midwest and he campaigned a FP.40 with a diesel head but he had consistency problems I think. And yes, you do get a 5 point bonus in OTS for using a diesel engine, thanks to the rule changed championed by the late Jim Thomerson, who was a master of the diesel engine. I have some diesels stuff stashed away, including a Doctor Diesel book, that I want to play wit just for the experience in the near future. I just acquired a gallon of real, pure ether from Gary Frost's estate and it should come in handy for mixing fuel!!
Type at you later,
Dan McEntee
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I would start with an APC 11.5x4. Try that, an APC 11x4, an APC 12.75x3.75, and (if you can get one) a Thunder Tiger 11x4.5.
You will need to spend some time familiarizing yourself with the engine. You need the right prop & venturi for the plane; that's not going to happen with the first thing you throw together.
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he best running FP 40 that I have is in a Cardinal.
It has the OS NVA, FP 20/25 venturi (6.5mm ID), Bolly Clubman 11.5" x 5" prop (very similar to the APC 11.5" x 4.5") and the Bob Zambelli head mod.
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I would start with an APC 11.5x4. Try that, an APC 11x4, an APC 12.75x3.75, and (if you can get one) a Thunder Tiger 11x4.5.
You will need to spend some time familiarizing yourself with the engine. You need the right prop & venturi for the plane; that's not going to happen with the first thing you throw together.
I have many 100s of the Cyclone props, in all sizes and also the 11 x 4.5
Randy
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I run mine with a 10x6 apc prop, clunk tank w/muffler pressure, and the large venturi they include with em. I also use wildcat 10% that I doctor up with BeNol castor oil (I add 2-2/3 cups to a gallon) and OS hot plugs. runs sweet, plenty of grunt, no runaways...
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also use wildcat 10% that I doctor up with BeNol castor oil (I add 2-2/3 cups to a gallon) and OS hot plugs.
21 ounces?!? What was the oil content before doctoring?
Mark
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I have many 100s of the Cyclone props, in all sizes and also the 11 x 4.5
Randy
I bought a few bags of these. I'd recommend this prop also.
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21 ounces?!? What was the oil content before doctoring?
Mark
Wildcat fuel is about 17% oil...
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Wildcat fuel is about 17% oil...
Which, no matter how you cut it, it going to be way too much.
Brett
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5 ounces of oil will bring 17% total oil up to 22%, which should be fine for the 40FP.
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6.4 ounces will get it very close to 22% if it is 17 now, BUT you need to know if that 17% is measure by weight or volume
Randy
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Which, no matter how you cut it, it going to be way too much.
Brett
17% oil is way too much, or 17% + 2-2/3 cups added oil to the gallon of 17%?
I think you mean the later, but want to make sure.
I use the 11/11 (22% oil) in my OS's. I think that is the correct amount?
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17% oil is way too much, or 17% + 2-2/3 cups added oil to the gallon of 17%?
I think you mean the later, but want to make sure.
I use the 11/11 (22% oil) in my OS's. I think that is the correct amount?
The end result is about 33%, which is way too much! Any regular fuel should be OK.
Brett
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If you add 2-2/3 cups of oil to the gallon before burning any, and now have two containers boxed together containing a total of 149.33 fl. oz. then the total oil percentage is 29%, and the nitro percentage is reduced to about 8-1/2 percent. I don't see a good reason to run that much oil in an FP unless you are trying to "tame it." I suppose if you can keep the plug lit, and can find someone to launch it, it's all good. When I ran a mix like that in an OS FSR, the run was inconsistent, at best.
If you pour off (or burn up) 2-2/3 cups of fuel before you add your supplemental oil, then things get really slimy. That gives an oil percentage of 31% and a nitro percentage of 8.2%.
This all assumes (as Randy noted) that the original mix is by volume.
Wildcat varies by label--and none of it is advertised as 17%. They have 16% and 18%, for example. See it here:
http://www.byronfuels.com/products/compare_wildcat.html
Dave
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... I don't see a good reason to run that much oil in an FP unless you are trying to "tame it." ...
I run mine with a 10x6 apc prop, clunk tank w/muffler pressure, and the large venturi they include with em. I also use wildcat 10% that I doctor up with BeNol castor oil (I add 2-2/3 cups to a gallon) and OS hot plugs. runs sweet, plenty of grunt, no runaways...
I think we may have an explanation. He's running it like a Fox 35, instead of the way that most people have found success with it. I'm still going to advocate for one of the props (or similar) that I suggested and a properly-sized (small-ish) venturi. I'm not sure how he's managing the no runaways, unless the extra castor is keeping the thing so very cool that it never gets up to normal operating temperature.
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21 ounces?!? What was the oil content before doctoring?
Mark
it's 17%, 80/20 syn/castor. I use the extra oil for my fox motors, but the FP's seem to love it as well.
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correction, 18%, stupid fingers....
also use the hot OS #6 plug.
seems to run great for me. your mileage may vary....
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I have been told the difference between weight and volume but need a refresher course in with what the difference is .. And which is the better? Thanks
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Here is the refresher course--
The density of the three ingredients are all different. If they were the same, then there would be no difference between a percent by volume mix and a percent by weight mix.
The densities are as follows: Nitromethane 1.14 gm/cc; Castor 0.961 gm/cc; methanol 0.79 gm/cc
For reference, the density of water at 25C is 1.00 gm/cc
We assume that the ingredients are not miscible, thereby screwing up volume-after-mix observations or calculations
Example
For a 10N, 22C, 68Al fuel mix by volume, the mix by weight would be 13.22N, 24.51C, 62.28Al. So if you are accustomed to thinking in volume measurements what has been working well for you, you can see that you would have to specify a higher oil content percentage if it were communicated on the basis of weight. Else, you would be a few percent short.
Conversely, if you used your "normal" percentages (volume) but your fuel mixer assumes you meant by weight, because that may be how he does it, then...
A 10N, 22C, 68Al fuel mix by weight, results in a 7.45N, 19.44C, 73.11Al mix by volume
Your engine would not run exactly the same. As you run a lower and lower oil percentage, this unintended "reduction" might be critical and cause damage.
Note that the alcohol constituent is by far the least expensive of the three. A cynic might say that a fuel mixer would make his product based on weight, but be vague about the basis, because it lets him put a percent for nitro and oil on the bottle that make you feel good, but reduces his costs significantly.
Note that it does not matter how the manufacturer is blending; in other words whether he uses a flowmeter or a scale or a whatever (as long as it is accurate) but we need to know the basis for the percentage given. I think all of us using the fuel assume that the percentage is by volume. But if the peerson blending does not follow this convention, and it isn't stated on the bottle, then we are not going to be happy with the results.
I thought that I could get to the bottom of this by looking up the Manufacturer's Safety Data Sheets (MSDS) which are required for chemical products. Unfortunately, the ones I have looked up did not give the basis of the percentage which surprised me, and further that most are also written giving a huge range in percentage of the ingredients. So they are not useful for our purpose here.
That leaves you with the same evaporative measurement testing that has been described in other posts. Unless you are doing large samples, or have very accurate measuring capabilities, you probably are not learning the true composition of your fuel.
Hope this helps,
Dave