Oriental ARF assembly

Rusty, I forgot which version Fp you have. We like to use the APC 10.5 x 4.5. This has little blade area and looks like a scalpel. This works quite well on the ABN version. The iron piston prefers a bit less rpm's and the TT prop I sent would work better. APC also makes a 11x4. Knowing what version you have would be helpful. We also run Powermaster in both version regardless of configuration. Ken

I think it's an ABN

Rusty, 100% certainty you have a ABN version. No bump in the case on the exhaust side and the placard casted on the opposing side is wider. Here's a pic of the OS FP iron version.    I purchased this brand new iron piston version In 1983. It's been in the box and never run. This is the OS control line-S version for stunt. Here's the examples side by side. You can clearly see the difference in the case by the bump I mentioned on the forward portion of the case. You can also see the differences in the casting amongst the lettering. No need to find a magnet or take the engine apart, just give it a visual. The iron piston was used on the FP.20, .FP.25, FP.35, Fp.40. The FP .20 is one mean little engine and to my surprise it can really fly some very large planes. Ken


OS FP .40 ABN on the left and the iron piston on the right

OS FP.40 iron piston version with the raised bump on the case   Ken

The Oriental is looking pretty good now. I should be able to fly her on Tuesday. Today I finished carving and painting the new wider fairing that fits over the stab and the top of the rudder glues to. That's on it now, and the rattlecan yellow is a pretty good match. The tank withstood a grueling pressure test, the engine ran on the bench yesterday and all that is bolted, plumbed and sealed up. I have a tongue muffler coming from RSM that I'm hoping gets here Monday. If not, I'll maiden loud without the cowling. I met Eric Rule today, he called me on the phone with a question about my order. We had a really fun chat. He sometimes works with Wayne on model details and trimming new products, so we had some common ground. Then i got an e-mail that he'd knocked $5 bucks off the shipping.

Anyway I have 2 each of several props ordered which also won't be here for tuesday, but I have a Zinger 11x5(I called it an 11x6 yesterday) that I can start with. I checked the venturi on my FP .40 and it's the same as the one on the FP .25, so that should be plenty economical. I'm worried that the 4oz tank won't run long enough, but I'll address that later. Just gotta get it in the air first.

And I need to look at pictures to see where the canopy goes. I think I can look back and somewhere around here, see Ken's explanation of attaching it. I've never done one before.
Rusty

I have to ask, have you run this engine using the venturi that's currently in it? When you say it's the same one in the .25, did you take one out of the .25 to put in it. If so, this could be a real issue. The .25 venturi is the smaller one which is about .265". Running a FP .40 on this size venturi could possibly rob lots of power and make it run hot. This is all dependent on many factors like prop load, engine load and temperature outside not too mention how many head gaskets are currently in the engine. This can be a real fussy engine if you don't have all correct. The RSm tongue has very small holes in it which in my opinion should be opened up. The holes however are very close together which sometimes can't be opened up without breaking into the neighboring hole. The solution is to entirely drill through the existing holes and exit directly out the other side. You could also add a additional set of symmetrically placed holes just above the existing ones. Too much restriction will also use less fuel but it will trigger the engine into running away if it gets too hot. The current spraybar in your engine is also relative to your venturi size. The older ones and now I can't remember are either slightly smaller or it's the other way around. I've never been very successful with running a 4 oz. tank to get the pattern in on a FP .40. I always used 4.5 or larger. This doesn't mean it can't be done.

Your prop choice of 11x5 in my opinion will possibly get your fuel economy but it could also make the plane fly too fast or overheat and cause runaway. I would say the FP would be happier with lighter pitch in the 4- 4.5 range. I do know many that use the prop you have, but be prepared because if the engine runs away, your hanging onto it for at least 2 additional minutes which feels like an eternity. I say this all the time, the FP.40 is a great engine, you just have to find it's sweet spot. You will notice how temperature and humidity are very critical to this engine. Your needle settings will change throughout the day from morning to evening. While you may get your pattern in on the hotter days, this won't be the situation in the fall when the engine starts using more fuel. Ken

I have 10.5x4.5 props ordered, as well as the glow plug you suggested.
All I did is probe the top of the venturi with the butt of some drill bits, seeing how large of a bit would go in far enough to touch the spraybar, and compared the 40 and the 25. It seemed about the same. I have the 35 currently with the spraybar removed, so I'll take it out and measure it.
Rusty

Rusty, Dennis Moritz has written many articles on the FP .40. These have been posted many times and I'm certain a search would reveal the article probably titled  Philly Flier setup. While the west coast crowd has their version which usually consists of a choked down venturi, our setup is different. You can get many different answers but I will say that the FP setup we use on the east coast works fine as is with no modifications with the exception of a additional head gasket running the APC 10.5 x 4.5.

Here's a post from  Dennis Moritz
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Re: OS 35 FP economy expectations.
« Reply #16 on: September 07, 2014, 06:30:20 AM »

I like to start with .272 venturi and 10.5x4.5 apc sport prop. Light plane. Tongue muffler takes weight off the nose. Should be able to remove tail weight. Fly the plane with the setup you have. If run is 6 and half minutes or longer. You probably are carrying enough fuel for the pattern. Fly the pattern. If you're running that long. Leave off the overhead eight and clover. Count laps left. Add maneuvers, if you have sufficient run time. Chicken hoppers work well, if you need more fuel in a limited space. Don't be afraid to run the FP in 2-stroke. It needs to run that way. If you are running away, open up the tongue muffler. Run the engine at a faster setting. Engine should stabilize. You can go down to a smaller venturi to reduce power, if your light plane is flying too fast. .265 is the small FP40/35 venturi.


You responded to this post  in regards to the question of whether or not 4 oz's is enough. My take is to try it. I will say I was struggling with the LA .40. I did notice Rusty that the LA .46's do the job on less fuel. I never officially measured the venturi sizes. I know that is why. Many feel the LA .40 is not stunt friendly, but I found that running them with a large venturi, Randy Smith tongue muffler drilled out using anywhere from 4.5 oz's- 5 oz's . This is not a good comparison to the Fp even though they're a descendant of the FP due to the FP having a additional boost port in the liner. This translates that the FP typically uses more fuel. Again, try it, fly it just be aware that you could possibly run into issues just out of the overhead 8 just prior to the clover leaf. For the above reasons is why Dennis suggests to leave out these maneuvers.  If fuel is that low this can lead to problems in the second loops of the overhead 8. This is typically the demise of most planes when the engine quits and the lines fall down around you as your running. USE CAUTION!!!!  

If this is a metal tank, take the tank apart and insure that the overflow pipe is all the way to the top of the tank. When filling, fill the tank SLOWLY with one wing tip down and nose high until fuel disperses from the overflow. Cap the pipes immediately so no siphoning takes place. pinch off the uniflow line or place a loop within it so that this pipe doesn't siphon. If you have to, leaning out the engine a click will give more economy but will certainly speed up lap times. Use 5% nitro and this will generally yield approx 5-7 more laps which might get you where you need to be. You have no comfort luxury in terms of room here.

Ken, Thanks for all the tips. When searching for FP 40 setups the other day, I saw Dennis' comments were consistent compared to others, so I did contact him. He gave me some good advice, which was also consistent with yours. Thanks, I will pay attention to details on this. And about fuel... when I ran out with the Ukey last week, it actually was in the second half of the OH8.
Rusty

I like to start with .272 venturi and 10.5x4.5 apc sport prop.

Looks like I have the right venturi. I can drop a .250" drill bit butt all the way to the spraybar, but not a 17/64". Those two sizes averaged are .2578". That's smaller, so it might be good for my economy. I'm sure it'll be powerful enough. If not, I can bore it. And I'll have those props, but probably not in time for the maiden. For that I have an 11x5 Zinger.

It will certainly be able to fly Tuesday. Except for wrapping the leadout ends, I could fly it now. With the big muffler it balances perfectly at 1-7/8" from the LE. I added the .9oz 3/8" wide vertical tail spreader. That gives more room in the elevator horn area if I need to adjust it through its side door. Also the reinforcing fillets under the stab are poplar, as is the fairing that runs from the fuse over the top of the stab where the rudder attaches. I may not need the tongue muffler after all. I forgot to weigh it, I may run out there after supper and put it on the scales.

I also still need to put a microballoon fillet on the top side wing root to cover up that ugly Gorilla glue that bubbled out in small lumps. They're so small that I don't have to sand them down, just put the fillet right over them. The cowl looks like it will only take a few minutes to fit. And the canopy, that might be a bit tedious, but if I have to, I'll maiden without it.

And that's it. I used the iron to tighten all the covering, checked all over for any oil and fuel entry areas, she looks good, I'm excited to get her in the air and learn this engine and inverted cranking. I'd be really happy if this can become my contest plane. Unlike the osprey I won't have to rush the trimming process and wreck it like I did the Osprey... showing off... badly... with Ron Cribbs watching. Lol-NOT!

RknRusty wrote:

I like to start with .272 venturi and 10.5x4.5 apc sport prop.

Looks like I have the right venturi. I can drop a .250" drill bit butt all the way to the spraybar, but not a 17/64". Those two sizes averaged are .2578". That's smaller, so it might be good for my economy. I'm sure it'll be powerful enough. If not, I can bore it. And I'll have those props, but probably not in time for the maiden. For that I have an 11x5 Zinger.

It will certainly be able to fly Tuesday. Except for wrapping the leadout ends, I could fly it now. With the big muffler it balances perfectly at 1-7/8" from the LE. I added the .9oz 3/8" wide vertical tail spreader. That gives more room in the elevator horn area if I need to adjust it through its side door. Also the reinforcing fillets under the stab are poplar, as is the fairing that runs from the fuse over the top of the stab where the rudder attaches. I may not need the tongue muffler after all. I forgot to weigh it, I may run out there after supper and put it on the scales.

I also still need to put a microballoon fillet on the top side wing root to cover up that ugly Gorilla glue that bubbled out in small lumps. They're so small that I don't have to sand them down, just put the fillet right over them. The cowl looks like it will only take a few minutes to fit. And the canopy, that might be a bit tedious, but if I have to, I'll maiden without it.

And that's it. I used the iron to tighten all the covering, checked all over for any oil and fuel entry areas, she looks good, I'm excited to get her in the air and learn this engine and inverted cranking. I'd be really happy if this can become my contest plane. Unlike the osprey I won't have to rush the trimming process and wreck it like I did the Osprey... showing off... badly... with Ron Cribbs watching. Lol-NOT!

one beautilful looking aircraft

Thanks, Rat.
I just went out and weighed it. Everything including the big muffler, cowl, canopy and tip weight comes out to 47.1 ounces. I hope that's within expectations. Sounds heavier than I expected, probably with the tongue muffler it will be more like 45.1 ounces. Of course if that will move the CG back too much, the tail weight isn't as easy to remove, but can be done.
Rusty

Good luck on your first flight, always like your post flight reports, photo and vids.

That is a good looking aircraft, looking forward to the flight report.

It's been a long time coming...hope it soars out of the gate!

Last minute details.The cowl actually went on pretty nicely. Curved nail scissors and a dremel sanding drum did the trick. Got a pretty fillet on the wing root. Sorry, no canopy, it got too late, so it looks like an unmanned drone Lol. No decals either, my usual MO.

Ken, I have the .257" venturi, which is the one Dennis told me to start with. I know you suggested I start with the .272", so I can drill one out if I need to, but can't make one smaller so easily. I'll let you know how it behaved with the small one.

My props haven't arrived, so I'll start with a Zinger 11x5 and take a fistfull of others with me too. I'll warm up with the Ukey and then put her up for a shakedown flight. It balances perfectly with no adjustments. Revised weight, now 46.4 ounces and that's with the big muffler. My tongue muffler should be here tomorrow. That should get it down another ounce. Got my video camera charging, so I can file an entertaining flight report.

All right,see y'all tomorrow.
Rusty

Rusty,
Take some Rev-Up and Zinger 11x4 props too. They are a real good choice for the FP. If the runaway problem crops up they will help a lot.
Typically the FP is thought to want to run at a lot lower rpm than it really does, and the extra pitch just makes it runaway. Especially with the stock muffler. It makes more, and useable power at high rpm when using a low pitch prop.

Chris...

Rusty, .265 is the small venturi. I don't know why it's so small. That could cause an issue especially combined with the RSM tongue muffler due to it having holes that are very small. Of course all of this is speculation until tried . Are you 100% certain .257 is the size? This engine may have worked for you successfully on a profile but your dealing with a bit more weight and load now not to mention the engine being cowled in. The RSM tongue may need a additional row or two of holes. Another solution is to drill through the existing and break out the back. As Chris mentioned the 5 pitch could also trigger the engine into runaway. Short tank the engine on it's first flight and see what happens. Ken

Ken Cook wrote:         Rusty, .265 is the small venturi. I don't know why it's so small. That could cause an issue especially combined with the RSM tongue muffler due to it having holes that are very small. Of course all of this is speculation until tried . Are you 100% certain .257 is the size? ...

No, I'm not, that's just my guestimate from probing with drill bits. I'll soon know whether it's a problem or not. I'd bore one as close as I can get to .272 before I leave, but I doubt if I have a bit that size, so it might take more time than I have. If the Oriental is a flop performancewise, I'll park it until I'm better prepared.
Rusty.

Rusty, don't bore it out yet. Try it first and see how it runs. I wouldn't do anything until you flew it and started into some maneuvers. Ken

Well? How did it go?

Yeah, I saw it right after I posted that...