This thread more than anything is the unwanted ******* child of comments made by some people who I respect in pattern circles.

For the record, I'm paraphrasing as I'm far too lazy to go hunting for the real comments.

Firstly Dave Lockhart mentioning that he feels that glow as a powerplant has it's days numbered, given the leaps and bounds made in electric circles.

Also, Mike Hester had mentioned that he thinks that a 140 rx would struggle to haul a BM v3 around with much authority given the increase in fuselage depth, and I assume increased frontal area, and wetted surface area drag.


I guess my question is, is there a home for the old 140 anymore? Are the to become the 61RF of the 2000's? I suppose this question has more resonance and relevance to thos who compete on a shoestring, like me and their existing ship is perhaps running out of usefulness, but there seems to be no aircraft that can use a 140, so is the engine also outliving it's usefulness?

The 140RX is a great engine . . arguably one of the best made.

A friend has one in a 4.7kg Integral, and it flys with authority . . no problem with power. Big Top Hats, Humpty's, stall turns are really quite impressive with it. It would probably struggle with a rolling vertical 'S' on a windy day . . but VERY adequate.

The "Aussie Icon", Tom Prosser still uses one (I believe) and is hard to beat on any given day.

Jason Shulman flew one in a John Payne designed Cyclone (owned by Henry Hutchinson - pic below) . . and won the Aust. Nats and Aust. Masters with it over fantastic pilots with great equipment, the likes of Alf Pye, Bill Bloodworth, Steve Coram, Chris Swain, etc. using OS200's, YS170's, Hackers, and Plettenbergs . .

So my guess it is far from a thing of the past. Probably more a case of matching an airframe to the motor. One combination I remember seeing was the OXAI Austral X with the OS140RX . . EXCELLENT performance.

Cheers, JB

I flew the 1.40RX's for years. They are great engines. My test now for engines it do a vertical snap and see if the plane will pull out with authority. It wont. It just doesn't have the torque. It's kind of like the YS 1.40's. Great engines, but their time has come and gone for a TRULY COMPETITIVE engine. There are just things that are better. In a VF3, the 1.40RX would be a dog. The 1.60FX is OK, but doesn't touch the performance of a YS 1.70 or a competitive electric setup. Great engine, but not for the size that the planes are getting now. You could fly one in a 10lb Prestige or lighter integral and get away with it in lower classes, but once again, do a vertical snap or multiple vertical rolls and when it gets to the top corners it is really struggling.

Arch

Yes, I agree with you, Arch . .

Although his question was . . "I guess my question is, is there a home for the old 140 anymore?" . . and I say, YES. But as you say (and I said, for that matter) it struggles in rolling vertical manouevres, even in a light Integral. BUT there are many, MANY pilots not flying at the more elite level. So, correct airframe choice is the key to having a really nice (and reliable) set-up to go fly . .

Cheers, JB

Jeff,

I totally agree. If you fly a little bit older, or a little bit smaller airframe, it is still an excellent engine. Just not quite enough for the large draggy airframes of today.

Arch

The OS 140RX no longer appears in the Tower catalog (2010 issue). I'm assuming the OS has finally ceased production of the engine [&o], but it has had a great run. As is typical in pattern, the aircraft designs eventually outgrow available engine power. My solution is simple: build smaller. Unfortunately it requires scratch building (which I enjoy), but it means that aircraft choice for the 140 is limited to what I want to hack out of a balsa log. I like the OS 140 too much to stop using it.
The next question might be... 'How long until pattern is an electric propulsion event?' The only viable glow power plant currently is the YS 170DZ (sadly, the OS 200 seems to have been a disappointment at least power-wise). Hopefully, YS will continue development of the 4-stroke powerplant. Maybe OS or Webra will produce a viable 2-stroke alternative, but I'm not holding my breath - the market just isn't very big.
-Will B.

Hmmm, surprised you didn't mention the OS160.....you got the OS140, OS200 but nothing at all on the OS160? Surprising indeed!

Unfortunately Glen, on an International level, the OS 1.60 is not a competitive engine. It is a great engine, but it still lacks to torque of the others mentioned.

Arch

Yeah, I suppose you're right....and now you can't get headers for it...

Glen

Rendegade,

Absolutely the OS140RX still has it's place in pattern today. Planes that are under 10 lbs (dry) and are relatively low drag can certainly be competitive in any class. For the higher classes, the pilot will need to be very skilled at tuning the engine to match the airframe and flying style. The torque curve will still be lacking compared to a YS 160DZ +, and certainly lacking compared to the current day electrics. The lighter cleaner airframes are increasingly less favored, the number of pilots very skilled at running the OS140RX are diminishing, and the trend of the planes is be draggier and heavier. All those things add up to limited days for the OS140RX.

Regards,

Dave Lockhart
Team Horizon/JR/Spektrum, Thunder Power, Castle Creations

Glen,

I talked to Al at Jtec about 2 weeks ago. They are getting the tubing benders necessary to start making headers. Hopefully by the first of the year, they will be able to start producing headers similar to the Mueller ones. He is getting the stuff to start making pipes for large gassers, but it will allow him to do the things we need as well,

Arch

Do you guys think that changes in schedule will ever cause people to want to go back to the less draggy airframes?

More than likely not. There is no advantage. The less draggy airframes were a result of not having the power needed. As the engines get bigger and more powerful, so will the airframes. The extra drag makes flying a constant speed much easier so the presentation is better. Plus, the rolling maneuvers are so much easier with the wide body fuses.

Arch

If that's the case, then why did Suzuki design the Mid Rex with such a skinny fuselage?

Hmmm, Archie, what do you think is more of a hindrance to the model? A 10% increase in drag or a 10% increase in weight? For that matter, a 25% increase in drag vs. a 10% increase in weight

MattK

Matt,

I would say the 10% drag. I know a 10lb Black Magic VF3 with the drag on it will NOT fly the Masters pattern COMPETITIVELY with an OS 1.40RX, but it does just fine with a YS 1.70 or electric setup with a lot of torque at close to 11lbs. Heck, my old Mantis at 9 3/4lbs still had problems in the summer heat in Muncie getting through the top of climbs with authority. I'm not saying they are not good engines, but I dont think they are a viable top level engine any longer. If they were, then why arent more people running them in Masters and FAI. I wouldn't have swtiched to YS had I not that it would be beneficial. I didn't do it just for the heck of it. I LOVED my OS 1.40's and ran several of them to near death.

Renegade,

A thin fuse doesnt mean less drag. There are many other areas to create drag without a really wide fuse. The mid-rex may be thin, but it is still a large airframe.

I don't claim to know all the ins and outs of drag as i'm not an aerospace engineer. However I have flown enough designs to know the differences.

Arch

Arch, my coment was more in reference your comment about wide body fuses. The mid rex is deeeeeep, make no mistake, but I fail to see how the width of the fuselage makes more or less difference on rolling maneuvres. Perhaps one of the pattern eggheads can fill me in here.

That said, understand the reasoning for wide bodies to create a bigger frontal area, and hence a more draggy aircraft.


Acutally, someone the change from 2 to 4 stroke, everyone points the finger at the torque. So is it fair to assume that it's the PROP that's able to be driven that's making the difference? Or the way the prop is driven. I'm just trying to get my head around it. With my 140 in a vertical snap there's no change in rpm, so I assume the struggle is because I now have excessive prop slip and am unable to increase my vertical (forward) speed effectively to get back up a speed where the prop becomes efficient? Conversely there is less prop slip or perhaps more disc area to get me back up to speed with a 4 cycle prop?

Just sounding it out guys.

Suzuki probably was going for a low fuse loading. Essentially the same thing as blowing up the fuse. I guess you could sit down and calculate resultant forces and all of the fun physics and aerodynamics to see if a smaller, albeit lighter airplane with less fuse loading will have better crosswind/knife edge performance than a larger fuse on. I imagine they're similar, however Suzuki, being a top level F3A competitor, likely designed that just for his tastes and played on a crazy idea he had.

I too ran the 1.40RX for the first two years of my flying pattern, and it was literally a fuel, flip, and fly motor. I think that's where I got most of my flight time, as it was cheap, easy to run, and reliable. Great motor, I've got two sitting here that I need to get rid of, as I likely won't be using them ever again, but I really enjoyed them while I flew them!

Maybe it's time someone started another chapter of the SPA.

The NRSOSKYAPA, the "not really so old school, kinda young acutally pattern association" where all the 140's in the world would find a home, in Patriots, Typhoons, and G202's..

Hey Rendegade,
That's really the direction I'd like to see the 'BPA' go in. Probably require a name change. I'd like to see a rolling 10 year limit (anything up to 10 years prior) which would allow new airplanes every year. I think it is safe to say that anything over 10 years old is probably not too competitive in the top 2 (maybe 3) pattern classes. The OS 140RX is 12 or 13 years old and that's a long time in pattern years.
-WIll

I will buy the argument that making the RX produce the required power is not trivial and not an excercise that anyone could undertake. Same is true with the Webras, which I still run and love. These are not the plug and play variety powerplants as YS could be and electric appears to be.

And prop development is not for everyone either. However, matching the power you have to a prop or two (for extremes in wind) to the model of choice, can be done and should be done by anyone deisring to compete at the highest level. Of these, the prop is the least understood and practically never played with. Bryan Hebert and Dave Lockhart are about the only other guys I know of (besides yours trully) who don't mind playing with the prop a bit. I suggest that some should try messing with this gizmo to extract max efficiency out of any set-up.

On the other hand I'd agree that most RX's I have oberved or have owned are slightly off the power that Webras develop. YS has nothing on the Webra 160. Unfortunately it appears that hardly anybody can make this thing run. I've not had hardly any problems with mine but I know I am the exception

Hey for those who care in an alternate, the Syssa 180 gasoline engine might be worth a closer look. Power is better on pattern props than the RX or W145 or YS140/160. But less than the YS170 and W160. Cost to purchase is reasonable, cost to operate is about 1/15th, cost to maintain will probably be practically zero on an annual basis, and weight is quite comparable to many of these and far lighter than electric. And you get the fine throttle of the special Walbro carb. Just a thought. Todd Syssa has been open to suggestions from pattern need point of view so we may have some news on a modified version also.

In a different thread I intend to have flying report in a pattern set-up soon if the weather holds

MattK

Rendegade,

The width of the fuse is a very small contributor to the total drag of a pattern model (remember the Hanson Excess?? Not slow or draggier by any measure, but much wider than anything at the time). Making the fuse wider does increase the % thickness of the fuse airfoil, and this generally makes it more efficient in knife edge. Making the fuse taller certainly makes it more efficient in knife edge because of the extra area. Keeping the fuse skinny does help keep weight of construction and finish materials down.

Regards,

Dave

Certainly it was not an easy engine to run, but the low end torque and linear throttle were fabulous. I think most missed the benefit of the Webra because they simply looked at peak RPM on the ground, which was often in favor of the YS. However, I think what was most missed was the whole package - power available on 15% nitro, easily under the noise limit at peak power, and the actual takeoff weight which could easily be 12 oz less due to the lighweight of the Webra and great fuel mileage (8 oz was enough for Masters). I do think the 170CDI shifts the balance tho, since it will make the power at lower RPM, and fuel mileage becomes similar (of course this is what, 5 years after the Webra??).

Regards,

Dave

I said before, and I still maintain . . the 140RX STILL has a place in Pattern.

Jas proved that he could win using a 140RX (and it was windy) . . Sure, doesn’t mean most could, but what it does mean is that a capable pilot can compete VERY adequately with this engine . . certainly in anything but FAI-F3A unless you are much better than average. (because this class is full of good pilots with optimized packages using top equipment).

The extra power is nice and definitely makes things easier . . but Pattern is all about precision . . and that is all you gotta do.

5B.4. CRITERIA FOR JUDGING MANOEUVRES
A high score should be given only if no major defects are found and the manoeuvre is well positioned. Judges must not allow themselves to be influenced by the performance of the model aircraft, and its propulsion method.

Sure, more power helps you reduce “defects” . . particularly if you are an average pilot (like me )

If I could not afford to run a YS, Hacker, Plettenberg, etc. I would STILL compete and use a 140RX (or 160FX), and I am sure I would optimise the package to give me the best possible chance.

I have seen a pilot take rounds off an Australian F3A Team Member with a 50 size electric (yes, he is also a great pilot) so . . as TNWalker has said before . . “you still gotta fly it”.

Cheers, JB

Dave, while I understand your point, I do have a few questions about your thoughts.


I agree on most of what you say, however, while increasing the % thickness will result in a "body" more conducive of lift at certain angle of attacks, surely aspect ratio must in fact have a HUGE effect on it, it can't all be side area. My point of view is that having a deeper fuselage for a given length should increase aspect ratio, albeit slightly, and should, (at least in my alcohol fuelled brain, it's 8:00 pm over here) be more efficient. I think this is where Nat Penton's voodoo express was heading, side area in higher aspect ratios, to gain the required efficiency for snazzy KE.

This has degenerated into a discussion about aircraft design, or is it an evolution of the discussion? Either way, I look forward to all your views.




Oh, and just so you know, I'm seriously considering cutting balsa on a smaller, lighter aircraft, with the deep/skinny styling of a mid-rex. I suppose before I do, I need to do some more research into "designed in" drag. I know that some years ago John Roncz was messing with airfoils that would provide low drag at low speed and insane amounts at high speed, (these airfoils were used on the full sized staudacher for all you IMAC loonies). I think if an aircraft can be wholistically designed with this premise, a more constant speed form of aircraft would ensue, with the added advantage of being able to be powered by a more feeble powerplant. At this point I see the design of F3A aircraft as flying drag machines, requiring gobs of power to overcome the inherent drag in the aircraft.

Am I trying to redesign the wheel? Am I a Pattern Heretic? Probably. Then again, when you have heroes like Burt Rutan, and Hanno Prettner (remember the calypso?) it's sorta par for the course.