OS 20 FP

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXCJ16&P=7

Iron/steel engines don't peel.

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"Alcohol is the anesthesia by which we endure the operation of life." -George Bernard Shaw

Ion

On piranha-infested rivers aligators swim on their backs.

Old Amazon saying

The bypass ports of the iron pistoned FPs all have a pronounced bypass bump on the ouside of the case. The newer ABN motors have the bypass ports blended in smoothly with the case. The ABN motors also have about 3 extra cylinder fins opposite the exhaust port. I have samples of both types but no digi camera to capture the image.

I see John helped me out with a photo of the old style case.
K

>Hi Kelvin,
>Just curious since I have never seen an FP with the old
>style case. I do have a Max 20 that is of the "S" series
>and looks like what you describe. All of the FPs I have
>seen have the same looking case. (??)
>Thanks,
>Bill <><
>
>When the character of a man is not clear to you, look at his
>friends.
>Japanese Proverb

I had two ABN .40 FPs which peeled. At that time I could still order the iron/steel piston/cylinders, and I did so and replaced them. From everything I hear, the true ABC setups are much better, and a large portion of the ABNs never gave any problems.

Also, I'm not forgetting - you guys are talking about the .20 FP, which is probably an entirely different critter.

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"I was with some Vietnamese recently, and some of them were smoking two cigarettes at the same time. That's the kind of customers we need!" -Jesse Helms

Well, to answer your question, absolutely, yes. You can put the ABN parts in the iron piston engine. And don't worry about the balance. No engine is truly balanced anyway, and, if anyting, you want a little more counterweight which is what you get with the older iron piston shaft.

Now, a little history. As far as I am concerned, the only reason to go to the ABN was because of the poor oil content in the fuel that the RC guys were using. You need more oil, and definitely more castor with the iron piston version. But, overall, I still liked it better.

What you have is the lightest case and the lightest shaft (fully machined out of bar stock) compared to a later version. The piston/cylinder is heavier on the ABN version (lighter piston, heavier sleeve). The first ABN engines used the same crank. Then OS got cheap and cut out a couple of machining operations (heavier with less counterweight). Then they cut out a couple more. Then they cast the crank. This is the one now being used in the LA. But all three cranks were used on the ABN version, and as far as I am concerned the earliest was the best (the one you have).

As to set up, there are many ways to do it. But it will run.

Easiest way to get proper setup information is in looking at the two most recent issues of Stunt News.

You really need to digest the (voluminous) information in most recent two issues of Stunt News.

As noted in second of two articles, my modded SIG Skyray 35, renamed Skyray 20, is a full 34.5 ounces, area is up to 450 square inches, airfoil deepened by 1/8". Model used in competition exactly once. To win Expert PA at Pacific NW Stuntathon, early June 2004.

More significantly, conditions for the day were brutal enough that I was flying Skyray 20 as I did not want to risk my Saito 56-powered Impact. I was (nearly) stunned to see how beautifully the model just punched through (Brett Buck terminology) a whole pile of gusty, bumpy wind.

You won't have to go far to find people who think model would be even better at 30 ounces or so. I do not share their view, and have the trophy (NW Skyraiders folding camp chair) to augment my side of any disputes likely to pop up.

And the 35 will run rings around the 25.

The best engine in the whole wide world is my set-up on the 35 FP.
So there, Danny boy. I have a better engine than you.

Sick of it.

Ready to puke.

Hmmm...

I recently, and hesitantly, checked in on a 20FP-related dissussion.

Your response at that time was:

"Aw, Dan, you can discuss it, just don't try to cram it down everybody's throat every time they ask about a different engine."

Leonard Neumann

Reference: http://www.clstunt.com/htdocs/dcforum/DCForumID1/10623.html


Other than me winning another contest, Expert P-40 at Fall Follies, this done with lowly "Dirtmobile," a thoroughly used and abused ARF Flite Streak, what has changed?

Oh, and Mike Hazel, CL Speed flier, was using same model in three classes, Classic, Sportsman P-40, Advanced PA. In latter he posted a personal high of 453, this on only his sixth flight with model. No appearance points.

At no time did Mike appear ready to puke. Well, maybe upon seeing the condition of said model he was tempted to projectile vomit; but not after he flew it in a single practice flight!

My comment had to do with the fact that once again you tried to hijack a thread. The question was one of piston/cylinder replacement for an engine he had purchased and venturi size. These answers were given to him by a number of responders. Then you stuck your neck in to say nothing other than "Dan is the expert on the 20 FP." You had to acknowledge that you knew nothing about the question at hand, but you were there to tell him what you wanted to tell him.

When that didn't work you referred him to your very misleading, voluminous, pile of junk that you sent in to Stunt News. As far as I am concerned that whole article is garbage. You just have to get in and try to make people think this is the only way to run the engine (which it is not) and that it is the best way to run this engine (which it certainly is not). This is Brett's set up for a stock engine when he didn't want to change anything and he found a prop that would work with that set-up. Fine, it works that way with a stock set-up. But that still doesn't mean that is the best way to run it.

Concerning the question of this thread, he is already changing things. Why should he go to stock? He can make it run better with a different venturi than stock and a different muffler than stock. Or he can run it the same way that Brett does, using the same prop and all, but still with a different venturi and a different muffler.

Yes, Dan, in a moment of weakness I said you could talk about it because you were trying to make yourself into a martyr. But you can't simply say anything about that engine without pushing your agenda. I am sick of it. Can't you understand that? Have you forgotten about all the e-mails that you badgered me with and all of the private messages that you badgered me with finally to the point where I told you you could have the last word but I wouldn't read them any longer? And there are three messages, as I recall that I still have not read and have no intention to read ever. They stand there as a monument to your getting your last word.

Well, you get the last word on those, but not on here. Apparently you also forgot the last e-mail I sent you after another post you had made, once again pushing your agenda, where I told you to quit mentioning it here. Yes, I told you to quit, because you cannot be a good boy. It is not in your nature to be a good boy and I am sick of you pushing your misleading junk.

Enough said. You brought up the subject. Now quit. Let's stick to helping people without trying to say there is only one way to do it.

You heard me say it now, didn't you? Quit! Enough. Finished. No more. (Oh, and remember, I locked you out once, too. Let's don't have to resort to that again, OK?)

You nailed it again.

BIGS

" What constitutes the dignity of a craft is that it creates a fellowship, that it binds men together and fashions for them a common language. For there is but one problem - the problem of human relations."

jonuck.

;) ;-) ;-) ;) :) ;) ;)

The problem here is castor varnish which kind of "glues" the engine together. You are probably lucky you even got the screws out. I have had several of these engines that after they had been run for a while I could not get the screws out as the screw heads get stuck down, and they use these nice little 2.5 mm screws with their tiny Allen wrenches that tend to strip out. I tried heat. I tried cold. I tried soaking in a crock pot. I tried a trick George Aldrich taught me of striking it with a punch. Nothing! I finally resorted to drilling the heads of the bolts off to disassemble the engine. And ironically, once you pop the bolt heads off, you can slide the engine head off and remove the remainder of the bolt that sticks out of the case with your fingers.

But back to your question, this is why your cylinder was stuck in the case. Clean it all with alcohol before reassembly and the new cylinder will simply drop into the case. You can push it in and pull it out with your fingers when new. And that is why there is a pin to align the cylinder in the correct position.

I will just warn you that when you put the new cylinder in, (obviously) put the piston and rod in place with the piston in the "Down" position. The higher the piston is in the sleeve, the tighter the fit and you will actually be able to raise and loser the sleeve a wee bit simply by turning the crankshaft. So, put the piston at bottom dead center and insert the cylinder and then put the head on and snug down the bolts. You want the head bolts evenly snug. Either go across the engine and snug them down, or go in a triangle pattern and then do the other three in the same way. Do not overtighten or you can strip the case (or the head of the bolt, or at least your Allen wrench.)

>My other query is re the wrist pin which on the one I
>took out seems to move freely in the piston but is an
>immovable fit in the conrod, is this by design?. Would
>welcome advice from any of you lads who have done this type
>of refurbish.
>
>jonuck.

The rod is also stuck on with varnish. This normally should be free and could even have been some of the cause of the engine's deterioration. Hit it with a bit of WD 40, soak it in alcohol, or simply drive it out with a punch. If you do use a punch, make sure you do not use a taper punch, but one that is of constant diameter somewhat smaller than the pin. Then place the piston on a block of wood in which you have drilled a hole somewhat larger than the piston pin and lightly tap the pin out of the rod. Once the pin is out, clean it with alcohol and lightly oil it before assembly. It should now be a very loose sliding fit over the rod and in the piston itself. It is a free floating rod made to expand, but at a different rate than the piston, so it needs to be free.

Oh, and I like to mark the rod with a lead pencil on the side that goes to the back. On the FP rods you can see which direction it should be facing the front of the engine (a slight chamfer in the bearing surface) but some rods will go either way. And once you replace the piston/cylinder, if you ever remove this again you want to make sure the piston faces that same direction when reinstalled.

I had the same problem with an OS .20FP I recently got off Ebay. Three of the six head bolts had the Allen heads stripped out. So I used a cut-off disc in my Dremel tool to cut a slot in the screw heads (granted, some slots were a bit off center because the cylinder cooling fins were in the way). Then I used a flat tip screwdriver, inserted in the newly cut slot, to screw them out. Didn't look pretty but it worked. I even reused the slotted screws when reassembling the engine after it was crock potted. It runs fine now.
DennisV

I have never understood that comment. I have had worn out engines where the piston would "fall through"!

Many years ago one of the engine guys (not George) showed me where he did this with a Fox 35. He custom fit the piston to the cylinder until it would, as you stated--completely dry, no oil--fall through the cylinder. I asked Duke Fox about that and he said "It's worn out." I tend to agree with Duke.

Well I have flown Dan's Flite Streak with his totally unmodified 20FP. I know you don't believe it, but it works. Actually it doesn't just work, it works very very well.

Is it the absolute best thing out there? Maybe not, but when Dan can substantiate his claims with contest winning results why would you want to discourage him from passing this information on to other people? At least try it before you knock it. If nothing else, it's a good out of the box starting point.

Let's see, you take a stock 20FP and use the (heavy) factory muffler (that can't possibly work like a pipe to regulate engine speed because we all know Brett Buck the aerospace engineer doesn't know anything about mathematics). You put an APC 9x4 prop on it and use Sig 10% fuel. Doing this you get a consistent and predictable run every time. Maybe, as you said earlier, a 25 will run rings around it. The trouble with that line of reasoning is that we're not trying to run rings around a particular engine. We're trying to get a consistent and predictable run every time.

Try it. You'll like it. It works. Every time.

Actually, I read the entire thread very carefully before replying.

Check message number 10 in this thread and you'll see that the question asked was "Would welcome a pointer to the article by Bret Buck on the setting up of this particular engine".

Then in message number 18 another question was directed to Dan "I am aiming this unit at a 10% larger version of George Aldrich's Peacemaker (Sort of like a Flitestreak), hope to bring this in at at around 30 Oz's----------am I being a little optimistic re the power expectations of this engine?".

Dan gave a reference to an excellent source of material that answers the questions asked. For supplying this information he gets told that other engines will work better and that he should stop talking about his proven setup.

Take a look at message number 20 "The best engine in the whole wide world is my set-up on the 35 FP.
So there, Danny boy. I have a better engine than you". That's a pretty mature response.

What part did I not get? A question was asked and an answer was given.

There, I've had my say about how I think certain people are mistreated on this forum and I will say no more about it.

OK, Neil, let me try. This whole thing goes back a ways. Dan has made an issue of this with an insistance that you can't change a thing beyond what he is running as per Brett's instructions.

First off, let me say this is not an issue with Brett. It is an issue with Dan. It is also not an issue with the engine. It is a fine little engine. All of the FP engines are. 35 and 40 FP engines have probably powered more airplanes in beginner/Intermediate/Advanced in the last ten years than any other engine. People are now using the LA because the FP is no longer available (new--although I do have a large stash laid away).

As to bore/stroke ratio, the 40 FP and 40 LA are the same. The 46 is a bored (same stroke) version of the 40. The bore/stroke on the 25 is about half way between that of the 35 and the 40. The bore only is smaller on the 20. The timing remains the same on the 35/40 FP (and the 40/46 LA). The timing remains the same on the 20 and 25 FP. What you can do with the 40 LA you can do with the 46 (or visa versa). What you can do with the 35 FP you can do with the 40 (with the exception that the bypass slots are cut wider on the sleeve and cause a problem with a "burp" in the intersections on upright mounted engines--but this is a different issue. This is not an issue with the 20 and 25 FP)

With all that said, We (Matt and I) have had extensive experience with the 35/40 FP, both stock and modified. Matt had his first wins in Advanced and in Expert with this engine. I have also had some personal experience with the 25. I have not messed much with the 20 since the 25 was available in the same case and is 25% larger. But anything you can do with the 20 you can do with the 25, only to a greater degree. Just be prepared to change props (it is a bigger engine) or to change venturis (throttle it back). It is totally false to say only the 20 will work and not the 25.

Now, there is a certain ratio of venturi to cubic inch displacement on the engine that applies to most all engines. (Stands to reason, doesn't it?) The bigger the engine, the bigger the venturi you need to use. The smaller the engine, the smaller the venturi you need to use. You can only inhale so much air with each piston stroke. A smaller engine needs a smaller venturi. The venturi is like a throttle (Maybe that makes more sense) but there is only so much opening you can give it. At a certain point you are not going to be able to inhale any more air, and even before that you won't get the proper air speed to draw fuel efficiently. Thus the ratios hold quite accurately. Using these ratios a .265 venturi is approximately correct for the 40 size engine (which is what was supplied with the 40 FP). Of course they also supplied the same size with the 35 and the 46 (That doesn't make sense, does it?) OS has since put a larger venturi on the 46. But, as I have pointed out many times, these venturi supplied engines are not intended to be the perfect set-up for stunt. They are just a control line engine. We make it into what we make it.

So, in stock form, the .265 venturi was supplied with the 35/40 FP and the .257 was supplied with the .20 and .25 (Hmm, doesn't seem quite right, now, does it?) The proper ratio (we compute the open area, of the venturi, minus the space consumed by the needle valve) would put the "correct" venturi for the .20 at about .228. For the .25 it would be about .238. I believe someone gave the .228 answer for the .20.

Now, I am one who believes in using open mufflers, mufflers that do not cause a lot of drag or back pressure on the exhaust. The stock muffler on the FP is quite draggy. It is quite restrictive. Run the engine open exhaust on a test stand and then hold the muffler up against it and see what it does.

Oh, and I had a special muffler made up for me once that had a constant bore to the chamber and a stinger end that I could slide in and out and attach at different points down the line. In other words, if the muffler were to act as a pipe, I now had a tuned muffler. I could make it longer and shorter at will. (I did my testing with a Magnum 53, by the way, but since the rpm is the same the lengths should also be the same). I found no difference in performance with any length tested with the muffler at its shortest point, longest point, or any point in between. I ran those tests on the test stand and we ran those tests in the air. And the shortest point was shorter than that of the muffler on the FP and the longest point was about an inch and a half beyond that length. By the way, with that muffler I put a 13 inch, 5.5 inch pitch, three blade prop on the engine, set it up open exhaust at 9000 rpm, which is what we were using for our launch speed at the time, and then held the muffler against the engine while taching it and there was no drop in rpm whatsoever. As I said, try that with the FP and the stock muffler. One thing length did make was tone. I could slide that muffler in and out and play it like a trombone. (Did you ever hear "Mary Had a Little Lamb" played with the exhaust tone of a muffler?)

OK, back to the point at hand. What do you do if you have a draggy muffler? You can change it out for a less draggy muffler. Or you can open the venturi to try to regain some of the lost power. It is the latter that I believe is happening with the draggy stock muffler and supplied oversize venturi. But the same venturi and muffler are used on the 25. You are not going to get the same performance out of a 25% larger engine using the same prop. Sure it is going to want to go faster. The answer is obvious: Use a bigger prop. You don't put the same prop on an ST 60 that you put on a Cox .049 (or an FP 20). You don't put the same prop on a 40 that you put on a 20. Why do you put it on the 25? What I have been saying is you can put a bigger prop on a 25 than you can on a 20. More power, more thrust, same type of run, same lap speeds. That is why I prefer a 25.

Now, if you put a less draggy muffler on the 20 size engine you can get more power. Want the same run as before? Put on the smaller venturi. I have said you can put a tongue muffler on it (This is where the argument with Dan started in the first place. Then it got completely out of hand.) If you (Dan) don't like the run because it is not draggy enough (You are still using the same prop and same venturi, right?) Then tap and plug the holes on the tongue muffler until you get the same amount of choke on the muffler that you have on the stock one. Or go to a smaller venturi. Or go to a bigger prop (More power because you have less restriction on the muffler). I would definitely suggest a smaller venturi because you get better suction. But I am offering solutions to a "problem". You don't answer by saying, "Don't change anything." Or worse, "I tried a tongue muffler and it didn't work." Well, did you choke it down (IS that what you want to do?) Or did you use a smaller (right size for the muffler and prop) venturi? Or did you try a different prop?

OK, these are the issues. Every time I suggest that you can change something, Dan says "No". Interesting.

Check the stats at the Nats some time and see how many people are running the most popular engine of today, the PA 61. Now check to see how they have it set up. Virtually everyone will have it set up differently. Are they wrong? Absolutely not! They have set it up to their preferences.

Now maybe you want to start with some standard. That is good. But there is nothing wrong with change to suit your preferences. If you mess it up, well, that is something else. Matt flew someone else's plane once who had just won a contest with it (PA 61 on a pipe) and it was so light on the lines Matt was afraid to take it over 45 degrees. He skipped the overhead stuff. Matt's plane pulls like a truck. That's his preference. Matt had Bob Hunt fly his plane this summer. Bob said the engine was coming on and off at just the right moments. He had no suggestions for change although he did comment that it had more pull on the lines than he is used to. That is personal preference. That is all it is. There is nothing wrong with either point of view. But you should never get so small as to say "You can only do it this way." (Then we end up with everyone flying the same plane--ARF--and the same engine--more ARF--all set up the same way. Boring!)

My point has never been to say that what Brett Buck set up for a stock engine, out of the box, with no changes, doesn't work. He achieved his goal of finding a setup for a stock engine that suited his liking. But it may not suit yours...or mine. That is no problem. Change it if you want. Dare to be different if different can make it better for you.

On the area of change, we always start with "square one". Then any change we make is compared to this. If it improves things, that is the new "square one". If not, then we go back. On trimming an airplane, you make one change at a time. Know where you are and where you are going. Trimming an engine is the same thing. One change at a time. If it didn't improve things, go back, or make smaller changes next time. Or try something else. Believe it or not, these other venturis do work. These other mufflers do work. These other props do work. THERE IS NO SUCH THING AS "DON'T MAKE ANY CHANGES."

On the other hand, there is also something to be said for finding a good set-up and running with it. Beginners and Intermediates especially need good set-ups. Brett's engine set up, flying that size airplane, at that lap speed, with that prop works for him. You can also fly the same set-up with a different muffler or venturi if you make the proper changes. Or a different prop with the proper changes. We don't use a different prop without making some other changes on our big ships. Why should we expect to do so on the smaller ones? And don't tell me that there is only one prop that works with one engine! Try different ones to see if they are better or worse or if something can be done to make them better. We didn't work up to a 12.5 inch diameter prop on the 35 FP by sitting around listening to someone telling us it won't work. Stretch the envelope.

That's my point. But Dan doesn't like my point. What I am sayhing is, you don't have to run it like I run it. I haven't even told you how I run it. But I have offered pointers on how you can change mufflers (lighter, less restrictive) or venturis to run it like you want to run it. (At least those are the comments I have made in the past where I keep getting challenged by Dan.)

>Check message number 10 in this thread and you'll see that
>the question asked was "Would welcome a pointer to the
>article by Bret Buck on the setting up of this particular
>engine".

Yup. And Dan didn't point to the article by Brett Buck. He pointed to an article written by Dan with a very big agenda and it says "don't change anything."

>Then in message number 18 another question was directed to
>Dan "I am aiming this unit at a 10% larger version of George
>Aldrich's Peacemaker (Sort of like a Flitestreak), hope to
>bring this in at at around 30 Oz's----------am I being a
>little optimistic re the power expectations of this
>engine?".
>
>Dan gave a reference to an excellent source of material that
>answers the questions asked. For supplying this information
>he gets told that other engines will work better and that he
>should stop talking about his proven setup.
>
>Take a look at message number 20 "The best engine in the
>whole wide world is my set-up on the 35 FP.
>So there, Danny boy. I have a better engine than you".
>That's a pretty mature response.

You forgot to mention message number 6 where Dan says, "I am not ignoring this thread, I simply do not have any experience with anything other than 20FP ABN engines."

What purpose did that serve other than to say, "Hey, I am here, and I am ready to go with my 'thing' again." If you don't have anything to say, and you were never in the discussion at all up to this point, and nobody asked you, you don't have to say anything.

But you don't know the background of all this. Dan wanted to say something. It reminds me of the guy on the campaign trail. You ask Kerry about his "plan" to fix Social Security is and he will come back saying, "First I would like to say something about Iraq." No, answer the question at hand. And don't ever say there is only one way to do it and you are the only one who knows how. I got so tired of Dan jumping on me every time I offered alternate suggestions that I finally did, indeed, tell Dan "no more." It wasn't serving a good purpose any longer. You don't enjoy these spats. And I don't enjoy these spats. And I have a lot more to do that try to explain myself. I have indeed told Dan, "No more". When I told him "no more" he went and put an article in Stunt News and now he is referring to that on the forum. (OK, no more, but here it is.).

My mentioning the other engines was directed straight at Dan. I did that only to show how stupidly assinine that sounds to be blowing your own horn. And you caught it. It did look stupid, didn't it?

Dan's "excellent source" is just another rehash of that "One way, don't change a thing" aspect. If he would simply stick with Brett's set up as a choice--meant for a stock engine with no changes--it wouldn't have been a problem. But there is the constant insistance that you can't change anything.

There is a lot more background here, but all that is immaterial.

>
>What part did I not get? A question was asked and an answer
>was given.

Dan loves to bait people, and I give him credit. He baited me. You missed the last comment before I cam back to show how stupid I look by tooting my horn about my engines (Dan's comment: "and have the trophy (NW Skyraiders folding camp chair) to augment my side of any disputes likely to pop up.") He knew he was going to get me, so I tried to show how stupid one looks when he merely toots his own hnorn.

You don't know about the e-mails I got from Dan (and others complaining about Dan). You didn't know about the private messages that I finally told Dan I would no longer read (and haven't) because it never ends.

That said, I would like to simply say, and say it politely, that Dan and I disagree and move on. Dan, I have been told by some, is a nice guy at heart. I have never met him (that I recall) but I have been told that he has been very helpful to a lot of people. Dan has a lot to offer. I have told him that. And that is why he is still on this forum. Dan also has a mean streak that seems to come out when he is on the key board. He loves to bait people. He has even said so in some of his posts. He loves controversy (Just read "Bad Boy Stunt"). I don't like controversy. That's why I reach the point of saying, "no more" when it comes to certain topics.

What I would realy like to see is "Dirty Dan" become "Mr. Clean" (But that name has already been taken.) I think we all have something to offer. And let's do it positively so we can all benefit.

>There, I've had my say about how I think certain people are
>mistreated on this forum and I will say no more about it.
>
>Neil Rogers
>Edmonton, Alberta

I will agree if everyone else will agree.

Scott(just a time keeper)Riese}>

And a great big "Gracious!"

It's a wonder a devious, under-handed, untrustworthy rascal like me has any friends at all.

Yes Dan, Sometimes I wonder if you have a tendency to self distruct at times. Happens to old, overweight, bearded men who insist in wearing a codpiece in public, and play with toy airplanes.
Seriously you should consider going back to being interesting rather then obnoxious at times. Your a lot more fun to read then.
Dennis

Your my friend....

Scott(hands are tied REAL tight)Riese

You are most welcome.

And thanks right back, as truly you get it. While, as requested/demanded by Len, I will no longer be discussing specifics on this site, there are indeed a great many people who *want* a detailed and very specific setup known to work every time.

As many of these people are on the margins of CL Stunt, getting them going in the right direction is hugely more important than, for example, PW's latest iteration of the Impact, which is the Hot Tip in piped 65s, and whether we ought be painting or using MonoKote to finish our models.

Brett's set-up is quite simple to explain. He was looking for a stock engine that could be run "out of the box." He settled on the 20 FP, and in his effort to keep it stock didn't want to change the muffler, venturi, or anything else. He found a prop that it would run with and went with that. I will grant him that. No problem.

Now, however, I have people coming to me with an FP 25 wanting to change it to a 20--new piston, cylinder, head, gasket set--all because they were told the 25 wouldn't work. But it does. I think it is a better engine than the 20. That is why I don't normally mess with the 20. (And OS must have thought the same thing. They don't make them any more.)

Then I get people who buy an RC engine on e-bay. Again they come to me wanting a too large venturi and a stock muffler because they were told not to change anything. They were told this is the only way it will run.

Now, if you want to run it exactly as Brett ran the stock engine, fine. If you have a stock engine and don't want to change the venturi, fine. But if you have nothing, you can put on a more correctly sized venturi and a lighter, less restrictive muffler, and it will run very well, thank you.

Ah, but I know, I don't know anything. Only the stock parts will work because OS is so smart in converting an RC engine to perfect stunt. And I suppose they are not so smart in doing the same thing with the 25, which again is why they dropped the 20. They did it just to frustrate you.

Bill

Sounds like a winner to me!

I have the FP 25's installed in Ukey 40's (one of the Ukeys is uglier than the other). The FP 20's are installed in a ARF Flight Streak and one in a solid balsa wing Flight Streak trainer.

I can honestly say having done extensive testing on all four engine types that they all work. I took them out of the box, put on a venturi/needle valve assy that I bought through Tower Hobbies and run-em.

I call a couple of my Buddy's up and ask them if they want to go to the ball field and crash all my airplanes. (Tear Up your Stuff? Sure, We're there!!!!)

All of my FP engines have un-earthed very easily after the yard dart test(s). They clean-up nice using a can of Brake Cleaner that I keep in my field box. They start easy, needle well, and bring me great joy for the amount of money that I having spent on them.

Our definition of "Stunt" is seeing if we can get all four of the planes started and in the air at the same time. A Butchers Picnic if you will. (the girls just sit on the tail gate and shake their heads)

WE HAVE A FLIPPING BLAST!!!! and isn't that what it's all about? Life is just entirely too short to worry or argue about model airplane engines.

I don't think I've ever had a problem with any OS Product.