Holton50

Guys, I'm in love with the Great Planes Patty Wagstaff, however our club requires 94db @ 9. I would like to know what engine/muffler/prop combination would work to get me flying.

Thanks in advance

beavertail

Im not an expert here. But a 3 bladed prop would definately help. Are you going gas?

DENNIS C

My Feedback: (99)

what motor are you using

Geistware

My Feedback: (16)

What muffler are you using. A pits Bisson muffler seems to be the quietest for my Brison 2.4

Holton50

I haven't decided on which engine or muffler to use. I was hoping to get a recommendation. But, I was thinking about going gas. Any ideas?

Bob Pastorello

My Feedback: (198)

No one will like this post much, so I'll don the flame suit, but here's how I see the "94 @ 9" rule(s)....they are carryovers from long-past times, when club cronies wanted to exclude;
Racing
Pattern
Warbirds
Giant Scale
or Anything that didn't suit their agenda.

SOME, and likely a few, REAL noise issues arose because people using any of the above toys WOULD NOT MANAGE THEIR NOISE!!! So "rules" were imposed in an effort to gain compliance.

Rules do NOT create "compliance", people do...and rather than effectively deal with personalities, "rules" were rammed through.

Now, the engines, and propeller/muffling systems are much more effective, and some pretty silent AND large combos can be had....BUT - IT will be IMPOSSIBLE to find ANYTHING that will pass THAT rule suitable for the PW Extra!!!

If your club is unmovable, and inflexible about the 94 at 9, you'd best find somewhere else to play, or sell the PW Extra. (To put that in perspective, the absolute, VERY quietest Pattern setups RIGHT NOW - USING THE BEST TECHNOLOGY AVAILABLE - can get 96 over concrete)

csintexas

Have you looked at the ZDZ50 and in fuselage silencer? I think it might fit with not to much work. You might talk to RCS about the db levels also like someone mentioned an over sized prop to slow the RPMs a bit and a three blade prop helps, A valocity stack may help a bit and the rear induction type carborators may help some specialy if you can shield them
the other trick is to set your radio so the engine is not runing 100% during the check you can use a spare switch to toggle that if you have a radio that will let you.

CranstonSnord

I agree with both Aerobob and CSI.

One, this airplane does not lend itself to making 94db.

Two, it could be done with a canister.

Three, judging from the questions that I see arise in assembling ARFs, it's not a job many ARF assemblers will feel comfortable doing.

Four, that kind of modification would render the type of warrenty that Great Planes has tried to extend to customers 100% invalid in case of failure.

Conclusion, that the GP Extra is a fine sport airplane, but not an airplane suitable for any type of competition where the noise rules are strictly followed. In cases where cheating is allowed, I guess that real noise control and rules are moot points.

I understand that there are some new ARF airplanes in this size category coming out this year that are being designed around canister exhaust systems and quiet tuned pipes. I think it is about time and the right thing to do. Not only for the neigbors. I do not like it when I fly my smaller airplanes and the one larger airplane in the air drowns out every other motor in the area.

When first introduced to the sound regulations in Europe, I thought it was a crock and totally unreasonable, but as I learned that quiet airplanes and unlimited performance are not at all mutually exclusive ideas, I have begun to appreciate the sound of a DA150 that does not rattle one's teeth out with a popping loud exhaust.

csintexas

I prefer the term "creative compliance"

IMAC has been dealing with issue over the last year or so. The regional director of my area has worked a lot on the issue. He said in a recent article that ground readings are not good indicators of actual noise levels.

I don't know of any 50cc class plane made to accept canister mufflers currently available.

If you did what you could to keep it quite and it still was just a bit over, so that limiting the RPM's on the ground would get you past the check than I seriously doubt any person could tell the difference in the air.

I've had others small glow engines make so much noise they drown out the sound of my engine.

The most common cause of complaints is not the noise in itself but the large flight area these big planes cover so a slightly noisey 27% plane may be much less offensive to the neighbors than a very quite 40%'er.

I also agree that we should work to keep the noise to a minimum. Until the manufactures can catch up with the times we have to do what we can.

Bob Pastorello

My Feedback: (198)

And I'm not saying "give up"...just suggesting that we need to be aware, and help EDUCATE folks about the "noise footprint", 'cause that's what it is....Larger airplanes, however loud they may be, generally are flown with "taller" verticals, and "wider" flightlines...this translates to sound traveling MUCH farther, and hence, potentially a far more significant impact on the surrounding area of the RC Field....

I think the issue has VERY little to do with the actual CLOSE proximity, as those drafting the rules will attest to. The efforts to date have made an impact, but the very idea of dialing down ATV on throttle to pass the GROUND check, then going full bore UP THERE - - - well, that's EXACTLY what can create the problem......

Larger gassers (particularly in prop 'rip mode') can have an easily heard radius of 2 miles, depending on wind...I think that's what our noise management focus should be about.

csintexas

I doubt anyone could tell the difference between 94 and 96 db.

I never said use a small prop and let it rip. I said do everything you can first.
If that is done it will be quiter than most giant scale aerobats.

Noise also has a lot to do with how you fly. Full power up lines make a lot of noise. A larger engine can pull a plane up without ever needing to go to full power a 50cc engine on the GP Extra would probably never actualy need full throttle to fly any IMAC class
if setting the ATV down for the ground check bothers you than just leave it down whenever you are flying at a field that requires a quiter engine.

Until reallistic measurements can be made the sound check is just BS anyway. You could get a 2 db difference just by being on different grass or softer dirt or a slightly different angle to the meter.

If a club is really serious about thier impact on the neihbors they need to just not allow large aircraft period or strictly control the flight area and stop silly db readings which are not very reliable.

CranstonSnord

There are quite a few airplanes in this class that fit cans quite readily. The first that comes to mind it the ZNLine Extra300S. 2.10m, about 12-14 pounds (achievable weights, not pipe dreams), this one was designed well before the advent of zdz or da 50s, but is just screaming for one of these motors and a nice canister muffler for a 75cc motor. There are quite a few European designs with fiberglass or composite fuselages and that is really the easiest way to get an airplane to fit a canister. Just food for thought for someone who may love the idea of a really practical sized airplane.

As far as prop rip, that is a matter of educating flyers to finding the right prop up front. Props get expensive...making the first choice wisely is half of that battle. That 32x10 Menz or Bolly gives great performance on the DA150, but not if the airplane is grounded due to noise. I'll go with the Fuchs 3 bladed and fly for the day. Performace will be very acceptable.

Back to the 50cc thing. A 50cc zdz or da plant in this airplane is more than unlimited verticle. So, using a more restrictive, quieter muffler and losing a few RPMs should not be much of an issue.

After the cowls are buttoned up, the motor/muffler is likely swimming in open space. There is normally enough room to almost double the effective canister volume. Throw away the old thumb-rules for chamber volume (where did those figures come from anyway?...do they really still apply) and use the available room in todays modern aerobats for larger cans on the easy to mount pitts mufflers. On some airplanes I have built, three times the canister volume could have easily been carried without hurting cooling airflow properties.

OK, just some thoughts.

Bob Pastorello

My Feedback: (198)

I *think* we may all be in agreement - except maybe the guy that asked the original question - BTW - Did we answer that?

ANYhow -
1. Current, and proposed GROUND measurements don't translate well to "perceived Airborne noise"
2. Noise control is a function of the airframe design and
3. Prop selection is a huge impact-er on the problem
4. Noise should be policed by those who are equipped to deal with it...enforcing a meaningless rule that doesn't address the issue just ain't gonna cut it...

Finally - cs - I didn't mean to infer that you had recommended "gaming" the rule...sorry if that's how it came across (I'm at work, and it IS *Monday*)....what I meant was that the PILOTS and OWNERS have to get this thing under control....period.

It would be nice if airframe designers could catch up....

csintexas

I'm sure there are a lot of kits available in Europe. If someone would start importing them to the US and the price was competitive we would be set.

Pelle Gris

Hi all...

To those who have doubt... My G-62 powered towplane swinging an APC 24x8 @ 7100rpm is right at 94dB @ 9ft. The engine is softmounted and uses a rear mounted Toni Clark 3 chamber silencer. With a little more effort on my part I think I could get it even lower. Have not tried all options yet.

Cheech

My Feedback: (19)

I have this (relevant) data to share. We are dealing with the sound issue at our filed just like half of the rest of the world. I won't debate the philosophies behind it all, but heres some recent numbers on engines that would make sense for thet CA.

The first sound measurement is at 9' , the second at 25'. Measured with meter 18" off the ground, meter perpendicular to the prop arc.

• 12/12/02 Brison 3.2 Gasoline 98 dB 91 dB Quiet. Overpropped. At Deer Grove, snow and hard grass.
• 12/12/02 BME 50 Gasoline 102 dB 95 dB At Deer Grove, hard frozen grass. H9 80" CAP 232 ARF
• 12/12/02 BME 44 Gasoline 100 dB 93 dB At Deer Grove, hard frozen grass. Dave Patrick Extra
• 2/3/03 Moki 2.1 2 Stroke Glow 96dB 90dB frozen ground
• 1/9/03 Zenoah G-62 Gasoline 103 at 9' Grass (no 25' measurement)

Our club intends to have a policy on sound as we enter the 2003 season.

CranstonSnord

Bob, I sure understand what you meant about cheating. In the USA with a real lack of proper mufflers for for effective quieting, if a moderate amount of cheating was not allowed, then IMAC would practically cease to exist. On Bisson, I think they are a beautifully made product. They simply are to loud. In my opinion, they should double the chamber volume and insert a deflector inside that the exhaust stream would strike before exiting through the cheese holed exhaust tubes.

I have seen the Tony Clark muffler on the G-62 and it is an amazing device. It is an in cowl muffler. The chamber volume is almost triple the size of the Bisson and it fits inside the cowl fairly. So far, though, there is nothing quite like it for the 50cc powerhouses. K&S makes side mounted mufflers for the Moki glow motors that are extremely effective. Unfortunately, the only side mounts I have seen for the gassers are for Zenoahs. For smaller chambered mufflers, they are also great.

However, there are some in cowl devices for the 50cc motors that can make a serious difference.

The first that comes to mind is a product by Aviation Alloys, available from Just Engines in the UK. I do not have the address here. When I get back home I shall post it here. Their in cowl mufflers are designed to meet strong anti-noise regulations.

Next is to have your existing muffler modified. A company named Bold Mufflers in the USA (Carl Rienbold I think is the guy's name) can modify your existing muffler. He can do all sorts of things to include making one to order. You can make one out of wood with the maximum canister size and he will create it from aluminum.

The little things like velocity stacks come into play after a suitable muffler and prop have been selected. These devices may gain one the half DB needed to make it, but first it is the big things that need fixing.

So, what is the easy solution? Maybe to send a few thousand letters to the Bisson company asking for more quieting power. The average modeler is not going to go to serious lengths to solve the problem, so a readily available, off the shelf product is going to be the number one answer.

Kato

It seems to be an general misunderstanding in the US that canister mufflers or similar sollutions restrict the engines and limits the vertical performance.

What is the true fact is that most gas engines needs a certain muffler volume with proper insides to perform to the maximum. The case is that your small mufflers (Johnson, Supersonic etc..)will result in less power from a gas engine compared to modern canister mufflers. With Canisters you gain both on lower noise and better performance.

Here in Europe close to nobody fly with these small mufflers, not only because of noise, also because of performance.

best regards
Kato

Bob Pastorello

My Feedback: (198)

Cheech - thanks for at least some data .... pretty solid indications of the 9' thing being impractical, at least in the situation you were testing in.

The custom mufflers from Just Engines in the UK appear to be a viable solution, as are the KS, Pefa, JMB, etc. "canisters" that are starting to be used successfully.

Right now, the muffling systems available are way ahead of the airframe structural designing....that's where the challenges are now, I think.

I'm reasonably hopeful things will evolve; they seem to, eventually.

csintexas

I designed and am building an 80" Edge 540T I built it to use the full length tuned pipe on a ZDZZ40.

It was fairly easy to do with the higher wing. It exits about 12" behind the wing. The engine was not the rear exhuast version so I ended up having to side mount the engine so that a little of the head goes through the cowl.
I couldn't even find the parts to make my own header.

I just test ran it the other day and it is very quite. I read an article a while back where a guy modified a Hanger9 Edge to use a full length pipe. I think he found a a carbon tube somewhere and just ran it through the fuselage.

It would be easy to do that with fiberglass and modify a plane to use a canister type muffler the RCS one even exits in the standard location the only thing is you have to either have a header fabricated or turn your engine sideways unless you use a rear exhaust