Has this engine seen any use/success in competitive CL Stunt?  I've read good things about the FA-72, but those aren't around and there is no parts support.  I've read things suggesting that the FA-82A was known for higher vibration but the 'B' model was a supposed improvement.  I couldn't find confirmation of that, however. 

Someone fill me in.  Is the FA-82B worth buying or must I hold out for a used or NOS FA-72 (and deal with the lack of parts support) if I want to try the 4-stroke thing?

Well, stunt engines, particularly 4strokes, are all about weight. If the 82 is heavier than the 72 you might hold out for the 72. If it is a bored out 72 it could be lighter than it would be worth it.

   Vibration is an absolute killer in these giant 4-strokes, even the 72 is pretty notorious for shaking stunt planes to bits.

     Brett

TOTAL 100% BULLSH!T.
That probably only happens to people who don’t know how to build a model airplane.
You don’t have a clue what you’re talking about.
I’m really sick and tired of all these people bad mouthing 4 stroke engines, most of whom have ZERO experience with them.
I’ve had experience with just about every 4 stroke engine up to and including the ENYA 90 and NEVER had a plane “shaken to bits”
As I recall, you made similar statements about the Fox 35.

#   Vibration is an absolute killer in these giant 4-strokes, even the 72 is pretty notorious for shaking stunt planes to bits.

     Brett

The torque produced during the power stroke in a four stroke is necessarily much greater than a two stroke. The negative torque during compression is also greater. I think this is often observed as vibration. I mean it is, but torsional. With aluminum pistons, most fourstrokes are balanced well in this sense. How it all works with airframe resonance is anyone's guess. Saito were very popular on profile fuselage RC models.

It's quite possible that a small difference in construction, prop, or RPM sets up an unhealthy resonance, but the chance of conditions coming together for actual failure is quite small.

Hi again,
What follows are some pics on how I built the noses of the planes you see in my previous post.
Nothing special, just a solid construction...

Claudio.

Well said, Claudio!!!

As previous mentioned, I've been a proponent of four cycle engines for around 25 years.
I've used nearly every brand and size up to the .90 and vibration was never an issue - neither in profile or full fuselage applications.

This anti-4S CRAP started many years ago when someone armed with nothing more than monumental ignorance posted an article all but condemning our great 4S powerplants. I don't know if he ever even used or flew one. Surprisinlg, a number of people actually believed the BS he was troweling out.

Some of the great pilots that I knew while working in Italy - Campostella, Cappi, Maggi and Semoli along with the Berringers from France worked absolute magic with these wonderful engines.

Just my 2 cents!!!

Bob Z.

Hi Bob!
Yes...when I decided to try 4 strokes back in 2009, I knew you were one of the most experienced modelers in the forum concerning 4 bangers
and read lots of your posts, which obviously helped me a great deal.
And yes, all the european modelers you've mentioned had been working with 4 strokes since year one...they were the pioneers if I'm not mistaken, specially Luciano Compostella!
Even Remi Beringer won the 2006 W. Champs in Valladolid with his french designed model and a Saito .56...I'm sure you've seen the videos of his flights...

The fact is, I just LOVE my .72! 

Thanks Bob.
Best regards,
Claudio.

TOTAL 100% BULLSH!T.
That probably only happens to people who don’t know how to build a model airplane.
You don’t have a clue what you’re talking about.
I’m really sick and tired of all these people bad mouthing 4 stroke engines, most of whom have ZERO experience with them.
I’ve had experience with just about every 4 stroke engine up to and including the ENYA 90 and NEVER had a plane “shaken to bits”
As I recall, you made similar statements about the Fox 35.

   Paul Walker and Gordan Delaney, among numerous others? Good call.

    Brett

So, what’s your point?

  My original point was that you need to take rather extreme precautions about putting large 4-strokes in models, because some of the failures I have seen are completely nuts, like Gordan's flap horn upright fatiguing to the point of failure from vibration.  I have said the same thing multiple times, but I guess you missed all of those.

   My secondary point was the you called the people you have had this happen, effectively, incompetent:

That probably only happens to people who don’t know how to build a model airplane..

   That was so incredibly insulting to other modelers that I thought I would point out how ridiculous it was. It's a real problem, people need to know it is a real problem, and claiming it isn't is a severe disservice to everyone, and irresponsible. You apparently were not aware of the two examples I gave, which is rather alarming for someone who proclaims themselves experts on the topic.

    I also note that all of these issues were associated with the 72, and even more so, the 82. No one I know of had much issue with the 56, or the engines from the other  manufacturers like Enya and OS.

   So, people need to be aware of this as an issue and proceed accordingly. Of course, no one needs to use a 4-stroke at all, since there are abundant superior approaches, but if they do, they better build it to handle the vibration.

      Brett

To be fair, it could also have been a bad solder joint. I think if the Saito FA-72 really was that bad on vibration to shake a plane to bits, we would have heard a lot more examples of this happening over the years that people have been working with them.

Here is a nice long article about the Saito FA-72 that maybe you have seen before. The author worked with the Saito FA-72 for years and helped others work with it too. It turns out the Saito FA-72 is a great stunt motor. He goes into the details about how to get the Saito FA-72 to work for CLPA, and there is not one mention in the article about concerns for the vibration of this motor or damaging the planes or having to build in extra strength. The fear must be overrated. Doesn't seem like a real problem for this motor.

http://www.flystunt.com/2014/01/28/four-stoke-findings-for-clpa/

Russ,
Very interesting information in article on 4 strokes. A couple of questions, have you tried undercamber props with the 4 strokes?

From some information I got in the past the Europeans like to use low pitch at the hub (like 6") and high pitch at the tips (like 8 -9") with the idea to take advantage of the grunt of the 4 stroke to pull the ship out of the corners.

Best,   DennisT

Lauri,
Yes it would be interesting if you can measure some of the Beringer props to see the pitch progression. I think we need to think of 4 Strokes more like electric or diesel then 2 stroke glows. There is lots of torque to harvest and I think maybe wider blades, maybe a little less diameter, with the progressive pitch and some undercamber might be the way to go.

Best,   DennisT

And for completely different prop info, Gordan Delaney ran his Saito .82 in his big Ki-61 Tony with a 13x3.8 3-blade carbon prop at around 10200 rpm on Powermaster YS20/20 fuel.

Now if you blokes drove real cars with real exhaust systems like Robert , you know how to make em work .      



It explains here , how you get your twelve foot exhaust pipe , and a can of paint .
Paint a line along the pipe , and it'll burn off first at the ' tuned lengths ' .
You then get a hacxksaw and cut it there . Multiples are best & quiter .
At four or five back from the head , you wont even need a muffler . 

MUFFLERS ? ? ?

These things are alledgedly a ' triple pass ' sucker . Front maybe a cone with reverse cone to center pipe aft , back through ovelaind middle pipe , then back again - out .
The de pulseified pulses  shielding the pulses acoustically . Well - the outer shell aint rattled by the pulses . Old Boy .

The OUTLET is AROUND the outer edge , notta pipe inthe middle .



Earlyer derivitives : easy to see that a front ' extractor cone ' passes to a parralel section . Even if it is flattened . The three little outlets being a sop to citified sensabilities .

THRUXTON ( Production Race ) ' mufflers ' ? were designed as a ' CONE ' ( megaphone ) to enhance output ( Top End ) with bits aft window dressing to ameliorate relations with the authorities .
TUNED LENGTH of he HEADER ( PIPE ) and Diameter have a significant effect on the powerband & output .The ' muffler ' can be used to create the multiple band effect we started on about ;

For a BROAD power response characteristic , perhaps. we hope .




THIS is a unflattened one , Glass Pack , straight through . Tho works better after the F'Glass packing has desintigrated . 




SO , The Theory , IS . Put on a extended header - to a ' centerline ' muffler . eva like a typical rear exhaust set up , or back aft . Where things have cooled off a bit . And you can get it quiter ( as its less pulsified ) and its more conveniant .
NOT to mention LOOKS a bleeding site tidyer . 

D = √((Displacement × Max RPM) / (88 × 1,728))

gets a 0.22 inch diameter header . 

https://calculatorshub.net/mechanical-calculators/exhaust-header-diameter-calculator/?expand_article=1

Which likely is tripe .

Theres a degree of skin friction . Where the outer flow is iirelevant , so the working diameter is slightly less than the actual pipe bore .

Then , ' rally ' tune for torque & respose is generally less than a max rpm output contrived system .

A few dudes fitted ' jet ' through tube set ups to stunt ships in the 70's . A exhaust tube exiting at the rear - a bitch to clean ? .
but throwing a few differant diameter long pipes on a test bench will get a basic ' non restrictive ' working size .
Getting a length that will enhance the arrangement , using a crayon to pick pulse lengths'd be next .

Modern automobiles are mandated near silent . Pity about the tyre noise . SO it wouldnt be imossable to ' silence ' a engine. 4 stroke or otherwise .
Maybe to electric levels .
Fuel Injection , woith a Igor ' G ' accelerometer - would get a high tech fueling set up . If theres minmiture injectors available .
Which are basically electric shuttle / shuffle valves . So not past the abiltity of our better machineists to contrive ( and patent ? )

One of those mouse cans back aft - fed by a long internal header - could get a reasonably competant exhaust system . With both power and ' silent ' running , perhaps .

This thread is a little of everything, lol. We started talking about the concern of the vibration of the Saito 72 and 82, then we got some responses about it, then we get some nice photos from Claudio using a Saito 72, then Bob and Brett start fighting, then we talk about props, then somehow we get onto race cars and motorcycles and mufflers, and then plans for the Caudron. It's an interesting thread!

I will be getting my stunt plane with the Saito FA-82 in the air in another month. Then I will have more to contribute.

Russell - Be very careful.
Just remember, according to an expert who, no doubt had hundreds of hours experience with four cycle engines, your plane may "shake itself to bits". Four cycle engines destroy control horns too!
I will relay  this information to my friends in Italy lest their aircraft suffer the same fate.
Please post some photos of your plane.
Bob Z.

ps - I'm not really fighting with brett - just laughing at him.

This thread is a little of everything, lol. We started talking about the concern of the vibration of the Saito 72 and 82, then we got some responses about it, then we get some nice photos from Claudio using a Saito 72, then Bob and Brett start fighting, then we talk about props, then somehow we get onto race cars and motorcycles and mufflers, and then plans for the Caudron. It's an interesting thread!

I will be getting my stunt plane with the Saito FA-82 in the air in another month. Then I will have more to contribute.

100% BULLSH!T.

Quite a difference between watching someone crash and having a great deal of experience.

I’ve never started digging because I might catch up with you.

But, in your defense, why not post a few photos of planes “shaken to bits” by four cycle engines.

My personal favorite is the broken control horn.

  Hopefully we can salvage something useful between meltdowns.

And yet it happened.  Gordan's flap horn did indeed break in his first big saito 82 powered Tony flying at the Nats one year.  The single 1/16" steel upright broke, and it was not a solder joint problem on this plane.

    You mean that the world's foremost self-proclaimed expert on 4-strokes was unaware of something that very famously happened in front of ~100 people at the biggest event in modeling? Another thing we learned from that was that Saito 82s are a lot more powerful than soybean plants, because it really mowed them up!

   For those not present, Gordan Delaney's "Tony", powered by a Saito 82 (up from the 72 he used previously, since it fits the same mounts) was flying at the NATs, either on the second day of qualifying or Top 20 day on Circle 4, suddenly started flying level and Gordan started yelling about having no control. It was slowly descending, so he walked it over to the soybean field where it skimmed lower and lower, until it finally dug up about 1/4 lap of soybeans, finally hitting the ground underneath and quitting. The subsequent post-mortem showed the horn upright broken in half, right through the metal. That was a massive surprise to everyone, we had seen some stress cracks and other vibration-related issues on other Saito 72 and 82 airplanes, but nothing where it buzzed up the horn and fatigued it in half in what was something like a few hundred flights. The 82 was fairly new at the time, so not a lot of history.

     I think everyone was astonished that you could cause such a failure. I had never even imagined that sort of failure was possible.  Everyone starting paying more attention, and then Paul's airplane at the 2004 WC proved the point. I note the original P-51 stayed together, so it's not every time, but often enough you should pay attention.

   That's when we all learned that the vibration level on these large 4-strokes was something you had to consider. I haven't about anyone having inordinate vibration issues with the 56 or 52 Surpass.

  Bob is a promoter and "enthusiast", not an expert. No problem with that, it's great to have enthusiasm for something.  He has been providing questionable technical advice from the instant they "discovered" Saitos. Dirty Dan was very gently making fun of him 25 years ago, when Bob was giving equivalently  faulty advice, specifically that what you needed for 4-stroke success was "t-21 style tanks, wood props, and the stock RC carb".

     It quickly became apparent that you didn't want to use the carb (random small speed changes) at least not unmodified, the hot setup was a carbon fiber 3-blade prop, and, in particular, you need a *clunk tank*, which is by far the most important bit of information.  Ted Fancher had discovered the carb issue 10+ years earlier on his Enya 46 and fixed it by sleeving the carb throat, leading him to design the Citation V around the Enya 46, and then won the 86 NATs using an ST46 and a large amount of lead.

    Both the bad advice, and the mocking rebuttal, was published in SN. Look around late 90's-early 2000s, the poop really hit the fan in the middle of 2003, and I think the "get Dan Rutherford" petition was presented and unanimously rejected by the EC at the 2003 NATs.  All very well documented.

   Somewhat to Bob's credit, having learned something from any number of a more competent experimenters (Brad Walker (mostly via Bill Wilson), the unfortunately late Bob Reeves, and others), he now recommends much more workable solutions and in that, his current advice is sound enough.  I note that he hasn't given any input on this issue aside from bad-mouthing me for daring to challenge him. I gather he thinks I am making this all up to "badmouth Saitos" - a topic for which I have little interest aside from my note of caution.

    Gordan, Paul, and others discovered these problems, apparently unbeknownst to and with no assistance from the "expert", worked through it despite the early bad advice, and came up with very nice, competitive, and durable airplanes. The 82 is a remarkably powerful and effective stunt engine by 4-stroke standards, and I can see how the ex-ST60 users would like it. It *was* a viable alternative to the all-conquering tuned pipe engines, as Paul showed.

     You just have to use a little care and make sure you build them tough enough with some consideration of the vibration issue. Of course, it's now mostly moot, the handwriting is on the wall for all IC engines, David's success notwithstanding. Even the very best tuned pipe engines (PA75, Jett 61, 46VF)  are marginally competitive only in the most knowledgeable hands against electric.


    Brett

   I had the whole nose of my Top Flite Score with a Saito .56 installed come flying off just after a demonstration at Oshkosh a few years back. Luckily, the engine hit no one, and the model survived well enough to be repaired and fly again. I think the incident had two causes. When flying the airplane before the nose separated, I often though how smooth the engine was running. I really felt nothing at the handle. It took me about three seasons to figure things out after reading up on Bob Reeves writings and few others. After that, I was liking what I had. Gilbert Berringer complimented me on how it rana nd flew after he put up a flight that year with it. I repaired the nose after pulling all the hot melt glue from all the joints that failed! Everything was reassembled with epoxy with a few extra gussets here and there, and then an over all coat of thinned epoxy. The model only gained about 1/2 ounce after the nose repair and the wing repair where the prop took a bit out of the right leading edge. And it flew just the same. The big difference was the vibration that I could feel at the handle after the nose was now much more solid. The props that I have been using are very well balanced. The engine landed on soft ground with out so much as a scratch and everything turns straight and true. The hot melt glue is one half of the problem and I know others have had a similar experience. I still have the airplane but it is in dire need of a recover job and will get that this winter. The next airplane I build for a four stroke will have a nose similar to what you would build for an ST.60 or what I imagine you would build for a PA.75 for sure. Nut i will do another one. It is an interesting type of power plant and I'm not finished playing with them just yet.
  Type at you later,
   Dan McEntee

   I had the whole nose of my Top Flite Score with a Saito .56 installed come flying off just after a demonstration at Oshkosh a few years back. Luckily, the engine hit no one, and the model survived well enough to be repaired and fly again. I think the incident had two causes. When flying the airplane before the nose separated, I often though how smooth the engine was running. I really felt nothing at the handle. It took me about three seasons to figure things out after reading up on Bob Reeves writings and few others. After that, I was liking what I had. Gilbert Berringer complimented me on how it rana nd flew after he put up a flight that year with it.

   I am not sure that this has anything to do with the 4-stroke, I have seen some pretty questionable workmanship in some of the Scores, it might have fallen off using a 40VF!  One hallmark characterstic of a 4-stroke is the low fuel consumption for a given power. That means that each firing has to be very "clean", meaning very energetic, and while the average torque and force is less than a conventional engine, the peak is almost certainly much higher, meaning it it putting energy into higher-frequencies. Hence it can buzz up things that you wouldn't expect, like Gordan's flap horn upright. Think "ping ping ping" instead of "thud thud thud" of a 2-stroke engine running blubbery rich to the point of misfire and blowing 60% of the fuel out the exhaust.

   For a given airspeed, you usually have less shaft power than a piped engine at the same speed, because the prop efficiency is much higher on the 4-stroke. But it's not the difference between 3 ounces a flight or 8.5 ounces a flight. This is also why the exhaust it much hotter on a 4-stroke, the only way to get more power/ounce of fuel is to burn it cleaner/hotter.

 

The next airplane I build for a four stroke will have a nose similar to what you would build for an ST.60 or what I imagine you would build for a PA.75 for sure.

   None of David's airplanes are extraordinary nose construction, it's more-or-less the same as any other piped engine and not much different that what we have done since the ST46 era (which was also not exactly a jet turbine). The one thing I (and many others) did learn from Jim Greenaway was the degree to which the engine mount and fuselage rigidity affected the engine run quality. I never did it to the same degree he recommended with the ST60, but was very careful to make sure it was very solid, that's why my ST46 runs were generally much more consistent than some of my cohorts. Didn't fix the rings, of course.

     Brett