Originally Posted by Mark Powell

I'm a bit of a HiFi buff. Most misic is loud at one watt or less with sensitive speakers. But what it is like in a plane I don't know. Higher frequencies attenuate very quickly with distance.

Personally I couldn't be bothered with a sound system. My planes tend to get over-complicated anyway. With most planes I don't care what it sounds like. But my vintage Junior 60 has an OS30 four stroke glow as I thought it sounded more 'vintage' than electric. It is wrong of course, four strokes were not used then, so the four stroke sound is too low frequency. And I do like my four stroke WW2 fighters, they give an 'impressionist' version of realism, which an electric certainly does not. But I like your slow three bladed prop suggestion.

Funny how real planes sound. The Merlin in the P51 sounds different from the near identical Merlin in the comparable engine mark of Spitfire. It CAN'T be the different screw threads they used

I've never really been tempted to bother with a sound system in my planes, but I've never seen one in action so maybe I'd change my mind if I did. Part of the appeal of electric though is that I can fly in places I wouldn't otherwise be able to fly without disturbing people.

I suspect the reason the Merlin sounds so different in a P-51 than in a Spitfire has largely to do with the prop. As you can tell by listening to a turboprop fly over quite a bit of the sound comes from the propeller itself, and I suspect the shape of the airframe influences the sound waves coming off the prop as they bounce off the fuselage in various ways.

Originally Posted by James_S

I suspect the reason the Merlin sounds so different in a P-51 than in a Spitfire has largely to do with the prop. As you can tell by listening to a turboprop fly over quite a bit of the sound comes from the propeller itself, and I suspect the shape of the airframe influences the sound waves coming off the prop as they bounce off the fuselage in various ways.

I've heard, that it's the radiator duct, that makes a difference in sound. Can't really say for sure. As far as my wife and I'm concerned, it's the best sound in the world. Heard the B-29 Fifi spin up it's four radials yesterday. That certainly sounded great too!

Originally Posted by L.A.

I've heard, that it's the radiator duct, that makes a difference in sound. Can't really say for sure. As far as my wife and I'm concerned, it's the best sound in the world. Heard the B-29 Fifi spin up it's four radials yesterday. That certainly sounded great too!

I toured Fifi a few weeks ago in Everett. She was supposed to fly that day but was having engine trouble. There were a bunch of other great birds though including a P-51 and a Spitfire, a DC-3 and loads of other stuff. The really cool part is you could walk right up and touch them and get a real good close look, usually that sort of thing is cordoned off behind ropes.

Originally Posted by flypaper 2

The old Byron Christen Eagle shown above has more power with the Turnigy motor than it had with the Quadra 52. Mostly due to the fact that it can swing a bigger prop at a lower RPM. Quadra swings a 20-8 prop and the Turnigy swings a 22-10. I had to hang the batts under the motor to get the CG right on both the Cap 10B and the Christen Eagle as the motors are much lighter than the gas motors. Takes about an hr. to charge the batts and giver again. Meanwhile I fly the little farts.

Gord.

To be fair a Quadra is a pretty under powered and over weight motor compared to more modern motors. A 20" prop is what you would spin on most 30-35cc motors and 21"-22" on some of the higher powered 35-40ccc motors. A modern 50cc motor will happily spin a 23"-24" prop.

This is my second go around in RC later in life. All electric this time around. My largest airplane, and my practical limit, is my 78" Extreme Flight Extra. It is purpose built for electric (cooling and some lightening and other features versus the gas version of the same airplane). So that helped me decide. It's a 13 lb airplane. I admit I have struggled with this question. I have invested in a couple of great battery chargers.

Dave

I know this thread has been going for a few days now but after some thought I figured I'd add this to the discussion. How big for electric comes down to your wallet. I prefer it regardless of size due to most of my stuff being multis but others don't want to shell out for batteries on a giant scale plane. Doesn't really have anything to do with the size of the plane. It has to do with the reason someone wants or doesn't want to do electric regardless of how big or small the airframe is. I have my reasons for electric (reliability on multi engine stuff) and someone else may feel that the sound of a gasser is more important. There's no way to say what's too small or large for electric or gas. It all depends on why either one is an option.

Originally Posted by tsymonds

I know this thread has been going for a few days now but after some thought I figured I'd add this to the discussion. How big for electric comes down to your wallet. I prefer it regardless of size due to most of my stuff being multis but others don't want to shell out for batteries on a giant scale plane. Doesn't really have anything to do with the size of the plane. It has to do with the reason someone wants or doesn't want to do electric regardless of how big or small the airframe is. I have my reasons for electric (reliability on multi engine stuff) and someone else may feel that the sound of a gasser is more important. There's no way to say what's too small or large for electric or gas. It all depends on why either one is an option.

Never any argument there from me. My reasoning was always based on my wallet. As I mentioned for me the break even is roughly around the 30cc-40cc sized aircraft get past there and gas financially makes more sense. But hey if you're willing to swallow the cost and want electric go for it.

As o e of the other posters I've got a 78" EF extra and the price to go gas or electric on that plane is similar. Step up to one of there 50cc size models though and the price breakdown leans in favor of the gas setup.

Originally Posted by luke352

Never any argument there from me. My reasoning was always based on my wallet. As I mentioned for me the break even is roughly around the 30cc-40cc sized aircraft get past there and gas financially makes more sense. But hey if you're willing to swallow the cost and want electric go for it.

As o e of the other posters I've got a 78" EF extra and the price to go gas or electric on that plane is similar. Step up to one of there 50cc size models though and the price breakdown leans in favor of the gas setup.

Agree 100% my largest EP system is 2800W in a 12-1/2 # MXRS. Which is probably gonna be my largest plane because of storage and transportation restraints.
Gas options keep getting smaller, too. I fly with a guy that has a sweet 20CC Sbach, about 64", I think. I'd say we see less than 10% nitro planes anymore.

Originally Posted by tsymonds

I know this thread has been going for a few days now but after some thought I figured I'd add this to the discussion. How big for electric comes down to your wallet. I prefer it regardless of size due to most of my stuff being multis but others don't want to shell out for batteries on a giant scale plane. Doesn't really have anything to do with the size of the plane. It has to do with the reason someone wants or doesn't want to do electric regardless of how big or small the airframe is. I have my reasons for electric (reliability on multi engine stuff) and someone else may feel that the sound of a gasser is more important. There's no way to say what's too small or large for electric or gas. It all depends on why either one is an option.

Multis? Yes. I even went so far as to fit my 78 inch DH88 Comet with a pair of electric motors at first so I could practice 'one engine out' flying high up and safely. With a couple of throttle to throttle switched mixers so I could cut either engine and then turn it back on regardless of the position of the main throttle stick. Then I fitted it with a couple of two stroke glow motors. Why? Because a pair of two stroke glows sound marvelous. Surprisingly, better than four strokes. Of course, in two years neither glow engine has ever failed. It's a tricky plane anyway, even with washout, due to its highly tapered wings.

As far as power to weight ratios go electric is generally more efficient up to about a 32 sized glow engine. That is a rough estimate and it all depends on expected flight times and states of tuning.
Above 32 size the volumetric efficiency of an IC engine can easily outstrip electrics.

If I were to build a plane that is of the larger sort, I'd go with a big supercharged YS and tweak it's tuning so it could swill vast quantities of high nitro fuel. I like the smell enough that I don't mind the clean-up.

If maximising power to weight ratios isn't a primary concern, then it boils down to "whatever floats your boat".
Two stroke gas motors are cheap to run. Sure, they sound stupid, but then so do Harleys.

Cheers!
Rocket

I believe the electric hobby has advanced a lot in the past 5 years. That includes sound. I build custom, hand-made sound systems for RC airplanes as well as full size replica cars. The transducer phenomenom as of late has really been making this worthwhile for most modelers because of the ease of installing them without holes. I have been testing and researching where to put them in the plane, and we have some amazing results. My system is more geared to the larger airplanes because it is a larger PC board and amp, but the total weight is only about 9 to 10 oz. total with 2 transducers. My sound architecture for the engine sounds is totally different from what is out there right now. Some flight videos:

Merlin

Real Sound Merlin RC Sound System with XT20 Wing Transducers (6 min 12 sec)

P51 Merlin Sound-Real Sound RC Sound System (6 min 26 sec)

PW Radial

P51 with Pratt-Whitney Radial Sound - Real Sound RC Sound System (6 min 31 sec)

Video guy was a little shaky:

Pratt Whitney Radial- Real Sound Rc Sound system (5 min 2 sec)

If you like turbines:

P51 Test Plane with Real Sound FA18 twin turbine sound (4 min 34 sec)

I guess when you are flying scale planes you want them to sound like the original aircraft. Very nice sound system effects.

What would be really effective would be to start that electric motor with the sound system off. And see what it sounds like. THEN turn the sound system on and REALLY appreciate what you get from that sound system.

I don't think they ever get to big

Over 250 flights. Pulls 120 amps on take off. 197" wing, 68 pounds, LMA1 AMA wavier.

DAG

Too big:

Too Big????? No! No! No! I'm working on electric motors for that! I am just having a hard time finding esc's and I have yet to figure out where to put the batteriessssssssss! (and still have room for cargo!)