stunthanger.com
Engine basics => Engine set up tips => Topic started by: gene poremba on May 29, 2014, 11:24:28 AM
-
I have a like new ( possibly never run ) OS FP 40 with R/C carb & muffler. Can i still get a venturi & tongue muffler for it? If so, where? I'm getting ready to build a Twister & would like to use this engine on it. Thank you...Gene
-
pretty sure you can easily find one,, if I recall, the FP 20 venturi fits,, and is sized well for use
there is a lot of info about running this engine if you do a search.
they CAN be a bit finicky to run tending to run away a bit but it is managable
great match for a twister
-
Lee's Machine Shop in the vendors corner.
-
Both RSM and Aero Products (Randy Smith) will have tongue mufflers for it. Randy also has very nice lightweight tube mufflers that will fit. 8)
-
there is a lot of info about running this engine if you do a search.
they CAN be a bit finicky to run tending to run away a bit but it is managable
Isn't this one of the engines that really responds well to a low-pitch prop in a wet two-stroke, and just pukes or runs away if you try to run it like a Fox 35?
-
Isn't this one of the engines that really responds well to a low-pitch prop in a wet two-stroke, and just pukes or runs away if you try to run it like a Fox 35?
Yes.
Brett
-
Wow! I was only off line for a few minutes & allready have lots of information. Thank you, i'm checking out all your leads.....Gene
-
The favored prop by many of the guys around here for this size of engine with Schnuerle porting is the ThunderTiger 11x4.5. You'll also see the APC 11x4 and 11.5x4 recommended. Some people like the APC 12.25 x 3.75 on the LA 46, but I don't know how it'll work on the FP.
-
A big bonus for a FP 35 or fp 40 is the mounting holes are the same as a la 46, even the backplate, prop washer and Venturi are interchangeable. La 46 is even lighter than the 40
So if the engine does not work out, you can do a easy swap for la 46. And have plenty of extra usable parts to experiment with,
I have had good results with both la and fp...but always best results were when run in the low pitch prop High rpm mode
-
A big bonus for a FP 35 or fp 40 is the mounting holes are the same as a la 46, even the backplate, prop washer and Venturi are interchangeable. La 46 is even lighter than the 40
Muffler, too? I know they're the same between the FP20 and the LA25.
-
Will Davis, where in NC are you located? I'm just off I-95 in Wilson NC, about 20 min from Raleigh
-
The Evolution 36 tongue muffler will also fit, and should be readily available for $14.99.
-
Will Davis, where in NC are you located? I'm just off I-95 in Wilson NC, about 20 min from Raleigh
Near Charlotte nc, we fly at Huntersville flying site , just north of Charlotte , not a long drive , join us for a fun day of flying
-
Will, i just googled Huntersville NC, & you are 206 miles or just over 3 hrs away from me. :( I wont rule out visiting your flying site, but it will probably be when you are haveing an event there....Gene
-
Sorry, FP20/25/LA25 mufflers are not interchangeable with the FP40 etc. series of engines. Add Brodak 40's and OS 35S' that have the same bolt pattern (but different case lengths) as the FP35,40,LA 40,46. 8)
-
The FP 20/25 venturi is probably the correct ID—Tower stock number LXCW99. The OS NVA is Tower stock number LXCR49. Both are straight drop-in.
Buy two venturis in case the stock FP 20/25 is too small. Push a 17/64" dia drill through an FP 20/25 venturi and you have the same size as the small venturi that used to come with the FP 35 and 40 when they were first released.
The APC 12.25 x 3.75 prop is probably too much for the FP 40—as noted, it's very good on the LA 46—some of my friends have cut it down to 11.5" dia and used it successfully on the FP 40. The other recommended props are worth trying as well.
-
Hey gene. Another thing i learned from Allen Brickhaus and i use, is get you some Sonic Tronic Glow devil 300 glowplugs. The FP .40 loves those glowplugs. All of my fp .40's have that plug in it and run great with it.
-
Kaz Minato has them both.
http://www.shop-online.jp/mnti/index.php?body=list&category_id=91189&PHPSESSID=01e95d8b087d123c7d0d4d92f2736f27
Jay
-
Scott Dinger makes great mufflers for just about any engine. As light or lighter than tongue mufflers. Have had great luck with them.
-
Will, i just googled Huntersville NC, & you are 206 miles or just over 3 hrs away from me. :( I wont rule out visiting your flying site, but it will probably be when you are having an event there....Gene
Hey Gene, put Huntersville on your calendar for September 27th. It's 1/2A day, but everyone brings their big planes too, and there's plenty of room for everyone to fly. It's a fun group to hang out with.
Rusty
-
Sorry, FP20/25/LA25 mufflers are not interchangeable with the FP40 etc. series of engines.
Argh -- I did not make myself clear. The LA40, LA46 and Tower 40 all have the same muffler mounting dimensions -- but I don't know about the FP-40.
However, OS kept the small motors the same from FP to LA, so maybe it did the same with the 40 size?
-
The E3030 standard muffler from the LA46 and LA40 will fit the FP40 and it isn't as restricted as the standard FP40 muffler. I know Geoff Goodworth suggests the FP 20 nva and venturi, but really they are a bit ion the small side for my liking. It does reduce the power output. I would use the standard FP40 venturi and NVA. Most props suggested will be near the mark, you need to select according to airframe size and weight. High rev, low pitch is the essential thing with these engines. A lot of people hate them, because of the frequent runaway situation that can result in trying to run them in the old fashioned way. Run properly they are good engines and don't deserve their evil reputation.
Andrew.
-
WHEW! lots to digest here. Rusty & Will, i marked my calender for the September event in Huntersville. I have a bunch of 1/2a stuff too.....Gene
-
WHEW! lots to digest here. Rusty & Will, i marked my calender for the September event in Huntersville. I have a bunch of 1/2a stuff too.....Gene
Any time you feel a need to be overloaded with friendly advise, just ask a question here!
-
OK, I'll try again: FP-35, FP-40, LA40, and LA-46s all have the same exhaust outlet mounting hole spacing, therefore a muffler for one will fit all. 8)
-
OK, I'll try again: FP-35, FP-40, LA40, and LA-46s all have the same exhaust outlet mounting hole spacing, therefore a muffler for one will fit all. 8)
And the Tower 40, which came with a muffler that looks and works a lot like the E-3030, but is much lighter and (last I heard, I haven't personally checked) is still available from Tower.
-
Andrew, in my limited experience of the FP 40, the ideal combination of propeller and venturi ID can vary with different aeroplanes—weight and wing area. Given that there are only two factory venturis available these days, the FP 20/25 and the large one that is stock in the LA 46-S, I found the large venturi too big for the model I flew with the FP and the engine ran away. I replaced the FP 40 with an LA 46, started with the 17/64" venturi—an FP 20/25 unit that I reamed out—but finished with the large factory venturi and the APC 12.25 x 3.75 prop. Happy days until a swirlling gust of wind grabbed the model at the top of a loop and blew it into the circle. I couldn't run backwards far enough or fast enough. :'(
The LA 46 venturi is the large one that came with the FP35 and 40 and the smaller one of the two was 6.75 mm ID or 17/64". Therefore, without knowing the model or the propeller, I will suggest that the large venturi is too big but one of the other sizes is likely to work—but which one.
The other question that begs an answer is, If you go to one of the after-market component suppliers for a venturi, what size will that person supply? It's an issue that everybody needs to understand.
-
Gene,
I have a couple of FP .40s with timing mods by Tom Dixon. I run 0.27 inch venturi, 11x4.5 prop at about 9800 rpm on a Jamison Special, 10/22 fuel. It's a very smooth running engine and does a great job on the Jamison. It worked great at the Topeka, KS contest last weekend. Tom's mods tamed the engine and made it much easier to use than the stock version. If you run it stock you will probably want to run a 4 pitch prop. Do not try to run it like a Fox .35 as it will likely runaway.
Jerry
-
Gene,
I have a couple of FP .40s with timing mods by Tom Dixon. I run 0.27 inch venturi, 11x4.5 prop at about 9800 rpm on a Jamison Special, 10/22 fuel. It's a very smooth running engine and does a great job on the Jamison. It worked great at the Topeka, KS contest last weekend. Tom's mods tamed the engine and made it much easier to use than the stock version. If you run it stock you will probably want to run a 4 pitch prop. Do not try to run it like a Fox .35 as it will likely runaway.
Jerry
Retiming the FP 40 is the best way to tame it into a stunt motor. However, you usually lose so much power doing it, you might as well bolt in a Fox. Maybe a bit more than that, but not much.
-
Clint,
Some power is lost in re-timing, but 9800 rpm with a 11X4.5 prop & 10% nitro is way stronger than any Fox .35 on 15% nitro I have owned. The FP puts out constant power with that set up, so I actually like the run characteristics better than the Fox. Some may like the 4-2-4 & higher pitched props of the Fox better than the FP. If you don't radically change the timing of the fp you can get a steady 2-2-2 run with a slight break and plenty of power using lower pitched props. If you change the timing too much you will radically change the power output. I know....I tried it.
Jerry
-
I have an FP 40 in a plane at the moment. It's a heavy (55 oz) profile beater with a Sig Chipmunk wing. The engine pulls that lead sled pretty good, but I have never seen it run in a 4 stroke. Start the flight in a wet 2, and before you know what happened it's leaned out and scorching through the pattern like the police are after it. 11x4 or 11x5 prop seems to keep it happy, but I suspect it's in a runaway condition. I just run the snot out of it and don't worry about it.
So, having said that, how would one go about "retiming" this engine? Are we simply removing metal here and there, or does it require degree wheels, micrometers and machine shops and such?
-
Start the flight in a wet 2, and before you know what happened it's leaned out and scorching through the pattern like the police are after it. 11x4 or 11x5 prop seems to keep it happy, but I suspect it's in a runaway condition.
This works for LA 46's, and (in my miniscule experience) with Tower 40's and the like. It leaves stuff out, and I've never had an FP 40 to try it on.
Tach it before you launch. If it runs away (yes, going to lean and "scorching through the pattern" is running away), then try launching it slower (by richening it up). My biggest problem with just doing taching and tweaking is finding a needle setting where it'll stay in a good 2-stroke, without either staying slobbery rich for the whole flight, or going into runaway. If you can't find a needle setting where it'll reliably stay at a good RPM, then try the following:
- More castor in the fuel (you should be running about 22 percent total oil, with at least 10% castor).
- A smaller venturi (or pile filters made of pantyhose over the venturi that you've got -- that works well, is adjustable, and filters are always good)
- Make sure the glow plug is hot, and in good condition
If it were my engine and that didn't work, my next step would be to ask here.
If it does work, then once you've established a baseline combination of fuel/prop/plug/venturi that works, play around with different props until you're really happy.
Do a search. I can't remember for sure, but if I recall correctly the FP 40 is an OK stunt engine if run right (in a wet 2-stroke) but the 40 LA can be a real bear -- and even then, there are folks who are happy with the LA 40. Someone will correct me if I'm wrong about the FP 40 being better than the LA 40.
So, having said that, how would one go about "retiming" this engine? Are we simply removing metal here and there, or does it require degree wheels, micrometers and machine shops and such?
Machine shops simply remove metal, precisely.
I've never retimed an engine. The closest I've come is to build a new cylinder for a Cox 09 TD, which wore out about 15 seconds after it was broken in (next time I'll be more diligent about getting all the lapping compound off the parts!). Some claim it can be "simply" done with a Dremel tool, and they may be right. But whether you're filing on it by hand or using a milling machine to do it super-precisely, you have to know how to not damage the plating on the liner, and how to restore the piston-liner fit when you're done, or all you'll end up with is a horribly scored-up P&L that doesn't work worth a damn.
-
If you feel the need,, Scott Riesse can make the FP work well,, he helped me do mine when I ran them,, and they were really predictable,, minimal change in power,, but much more tractable
-
I am running a 40FP-S on my Sig Banshee. Got the engine new and put about an hour on it on the bench before going flying. It come with 2 venturis in the box. I settled for the small one. Running 20% Klotz castor 80% methanol and a hot Merlin plug. Prop is a Top Flite 11x5 wood. After much tweaking I have found this engines sweet spot. It wil not do a 4/2 break like a Fox. But is quite happy in a wet 2 on launch. Breaks nicely into a full 2 cycle in manoeuvres. Holds a wet 2 until about the last 45 seconds of the flight. I am currently using a Du-Bro 4oz rc tank converted to uniflow and mounted to a saddle with zip ties. Seems to work well although I will try a metal uniflow at some stage too.
Anyway Lees Machine shop sell venturis. I don't know what size to go for though. Anyone able to say what the dia of the small one for the FP-S is? As for NVA the OS one works fine, there are ST variants which work too.
Dan.
-
Daniel, it should be 6.75mm or 17/64". If you don't have suitable measuring equipment, I suggest you see how loose the small venturi is on a 1/4" dia drill then see how a 17/64" drill fits. Just be sure that you use the shanks of the drills and drills that are not damaged in any way.