Artisan. . there are two basic types of ignition "pickups" . One uses a magnet to trigger a transistor-like device (on or off), which is Hall Effect, the other uses a coil/inductive pickup connected to a transistor in an amplifier, and the voltage spike generated as the magnet swings by triggers the circuit. There are a number of different designs of each type.

Of interest is that both 3W and DA use a 2-wire "inductive" style pickup (although there are 3 wires at the plug) that not only senses crank position, but also helps to advance the ignitions timing automatically depending on how fast the magnet passes the coil. Inside "the box" DA, 3W, CH, and others use basically the same style of ignition "amplifier", with toroidal coil, capacitors and resistors, a smattering of diodes and semi-conductor devices (transistors or their like) to fire the coils.

Ch, Pro-spark, and others, use the external Synchro-spark module to control timing. There is no such circuitry evident on the DA/3W style ignitions, meaning that "advance" is almost entirely a function of engine speed and how quickly the magnet brings the pickup coils voltage level high enough to trigger the ignition to fire. It's a very simple design, and virtually bulletproof.

As for the RPM #s on the air wild 27-10 on a DA the airwild prop that was taghed was my prop on another guys engine I also have another airwild 27-10 and it will turn 200 to 300 more on the same motor. so there is variables in props that will also allow rpm's to be higher or lower so what this DA turned on this airwild it might turn the same RPMS with the 27-10 you have so again comparing #s with out using the exact same prop does not tell you anything. Props vary in weight stiffness and this relates to how much they flex which can cause higher or lower RPMs depending on how the prop acts. I am still looking forward to seeing the engines run and seeing RPM numbers for myself inperson. As has been said some people have happy scales as well as happy tachs. Also Keith what is the status of the motors being ready.

Steve Hill

I agree wholeheartedly on the "variance' in props, Steve. . my TOC100 would turn a certain Mejzlik 28-10 at 6800, another at 6600, a third at 6650, and a 27-10 at 6550. . .and the person who bought it from me says it does no better than a "standard" 3W100 for power. . . go figure. These 28" props are molded from CF/epoxy, that all came out of the same exact mold. Kind of gives a bit of weight to the "forget the tach. . just fly the plane" argument.

Thanks, Kris.

I thought there was another kind of sensor, other than a Hall Effect Transistor or a swinging coil circuit that you fellows were talking about. Guess not.

55! Keep up the good work Keith! I am on the list for one. I certainly don't want one even a minute before they are ready, even if that takes into next year to have a strong and stable running ultra light engine. I still gotta figure out what plane to try with it. Might have to have a kit built to really take advantage of the light weight. Something really fun. An engine under 3lbs with that power, who knows?

Joe

Hill,

You are correct about the prop variations. But please read my post about rpm test we performed with the same material. It is my job to keep accurate records on the competition. I dont rely on hearsay for our information. Just ask what a ZDZ 80 will turn and you will get 1000 rpm spread. Is that a variance of props,motors or ego's. If Bob comes back to Waco I would like to see what our 28x10 mejzlik will turn on his DA. Especially if his is the best one you have seen as you told me. Maybe the oil spitting out the front bearing brought his rpm down the day we tacked it.


Keith
BME

GoeKeli. . how bout a "Patty" ARF Extra??? Amything up to about 16 lbs should be a real screamer with the 55 when it comes out.

Kris,
that is funny you mention that. I got one at home right now. I could yank the G45 off and all that tail weight and have a different plane all together. I have also though about looking for one used or cheap and pealing it, and lightening as much as possible. You know. Really go over it and get carbon gear etc.
Put it on a major diet. The extreem flight planes look good too. Quite a bit more scratch though. Your right I think, anything under 16 lbs will float.
What sort of props sizes is the 55 going to require or swing?

Joe

GoeKeli, it seems the 22-10 to 23-10 sizes will be the most effective on the 55 when it comes out. . Brands and blade shape will, of course, change how well the motor pulls a plane.

Keith will be doing a bit more testing before releasing the 55, I'm sure, but there are gong to be a LOT of happy people with 80-90" planes when it hits the market.

BTW. . the exhaust is timed for tuned canister style exhaust, though it will work okay with a "muffler" You might want to check on available room for a canister inside the fuselage. Also, BME has a prototype "inside cowl" canister style muffler being designed and tested. There are also 3-d CAD generated pictures of the 55's crankcase.

http://www.bmeengine.com/html/gallery.htm is the URL for the Cad drawings and other new stuff.

Please note, also, that the listed weight of the 55 is now 1.99 lbs .. really it's 1.98, but people love sales where things are priced at $___.99 cents This weight includes prop washer and nut, as well as sparkplug. Look for UNDER 2 lbs, 7 ounces with muffler and ignition in place.

Artisan, there is a third type of sensor. . LED light detecting triggers are fairly simple to make and very rugged, but no one has adapted them to our planes yet. All it takes is an emitter (LED) and photo-sensitive receptor, then either a slot or reflective plate, on the cranksahft. This circuit can be used to trigger any number of "Pulse' type amplifiers, including ignitions.

.

This thread has caught my eye. I have a GP Patty Wagstaff and was going to put a 50 in it. But with all of this talk about the 55 and being light then maybe I might wait a little while. What is the expected GA date for the BME 55 Extreme?

Lee

Things are right on track, Lnorris. Seems even our West Coast customs officials can't slow things down very much.

Believe me. . I'll be the FIRST to tell you when they start showing up, and it's not going to be very long.

As for an expected release date for the 55, Keith has about 500 orders for 110's to fill. . and a large number for 55's as well. He'll be shipping them as quickly as he is able.

Best bet. . wait for word that BME is shipping the motors, then get your order in. Quickly

where is a good place to keep my eye out for that info? Will call BME in the morning I guess. THanks for the info.

PS what will the going price be for those hot little babies?

Lee

Right now, a BME 110 is going for about $35,000.00 each, and a 55 is about $20,000.00

once they start producing them en masse, though, expect them to be priced about the same as the current engines of that size.

Kris -as you seem to have a good working relationship with the BME folks - -please give us all an idea as to how the tuned incowl setup, shown as a sneak peak will fit in a cowling - perhaps my metric scale is off but the drawing infers a quite large device.
Is there a smaller version?
Have you run one ?

Its on the drawing boards, Dick. That's all I know. Haven't seen, nor tested one. Keith said a prototype they are testing picked up 150 rpm or so, and had less 90 dB at 9 feet. Personally, I'd go with a "standard" canister setup, or a 2-into-1 system with single large canister. But, if they can get a system that FITS, it would be a very good thing.

Kris,

Since you have the inside track, I have heard a rumor that BME is "updating" the 60 twin for more power and lighter weight. Is there any truth to this rumor?

The entire line of BME engines is being upgraded, P-51. How far this takes the 61cc twin is a matter of degree. It's already a fantastic little engine, and there is really not very much in it's size range that can compare to it, except for "thumper" singles that are no more powerful and vibrate 10 times as badly, as well as weighing nearly as much I'd expect it to achieve lighter weight as the crankcases from BME evolve from the many upgrades associated with the Xtreme-110 and 95cc "Echo" based twins.

For the most pertinent information, it would be best to contact Keith at BME. . the number is 254-836-0835

Thanks- the 2-1 setup I saw - did not work well -and the theory on making it work well escapes me -
The dimensions on the setup shown on the BME page certainly looks good -but fitting that all into a cowl is a bit of a puzzle.
We try all sorts of tuned.non tuned devices and even some new in cowl stuff.
So far - nothing we have seen, that is TOTALLY in cowl -is both quiet AND capable of zero power loss. You get one or the other .
We have only seen DA/ZDZ and 3W on these tests -and frankly will be surprised to see one which does both.
The setup Al welded up - was a group of the KS curves which, when all welded together made 22" -into a can using the rear of the can as a reflector - much as the Chapman -or from the pics of the set up on the BME site - likely used on that prototype - it works and works well
the problem is that it simply can't be hung onto an engine -like the current crop of "in cowl" devices - (mufflers)
simply too much stuff to hang --and some kind of a vibration isolator and additional support is required.
The Zenoah mufflers -(lawn mower look alikes) are not all that bad -
and better than some "model types " which are just a tube on a box.
A "rat maze" in a box seems to have real possibilities -as the maze can be constructed to make a long path , in a confined area.
The hook in all of this is that an in cowl tuned muffler , which works great on one timing setup ( exhaust dwell) falls flat on it's asp using a different port setup.
The difference can be pretty high.
Anyway - I hope this setup BME is trying - is a success .
We are setting up a rather different "in cowl" muffler which is an attempt to keep it all in the cowl - One thing we are stuck with tho - It just can't hang on the two exhaust bolts .
the engine vibes will simply kill it in a short time .
The best so far looks like the "muffler " will be as large as the engine .
And that's about as small as it can be - to get better -it gets larger.
Any thing that beats this size problem wil surely be a winner .

You know, Dick, the entire silliness of having to have the muffler "in cowl", is just that. . silly.

Automobiles are made as an integrated system, so are computers, stereos, TV's entertainment packages and even thing as simple as a bicycle get the same thought process these days. I keep asking myself WHY we even bother with "in cowl" setups anymore. We have this HUGE plane (in comparison to the exhaust system). It's a simple matter to merely re-design the planes structure a little bit to make for a wider engine torque box, or totally eliminate it, leaving all sorts of room in the front of the plane for tuned exhausts. The entire aircraft should be an "Integrated Design" concept now, not a "bit of this and a tad of that" type of piece.

There's just wayy too much "old style" thinking in this hobby. I've been using Canisters for 3 years now, and can't remember the last time I used a "can" muffler I really can't even see the use of separate headers/mufflers. We should have systems, by now, with bolt-together header-muffler flanges instead of slip joints, manufactured-in hardpoints for mounting, and durable o-ring type hanger mounts like cars use.

Seems a bunch of people are still a "day late and dollar short" when it comes to solving these sorts of really simple problems.

yes a simple muffler and simple hookup
Easy to do
The problem is defining "easy".
Here is a pic of an "easy setup - the single cyl engine is tilted -the header is 5" long (overall) the can is 8" long - could be shorter and fatter .
a simple coupler at front - a round spud mount at rear - no tuning - just very quiet and less money than some "In cowl" ."mufflers?"
The concept will work on any engine.
The result is NO power losses and very quiet operation.
The downside
a small box -open on the bottom to let out heat.
The ARF flyers - typically do not want to ever touch a knife or a saw.
Ideally, they buy at the shop and head for the field.

Kris,

Did you know that there are other airplanes out there besides Extras, Caps, and Edges that use the type of engines that you have been talking about such as warbirds and civilian? Not all have the luxury of using a non engine compartment muffler. These need the development of better in cowl mufflers.

I think that there has been a lot of tunnel vision on this thread but very interesting.

Ken

.

Bigbird, simply angling the exhaust port of the cylinders back at a 45 degree angle would do wonders for EVERY plane out there, when it comes to exhaust installation. On a warbird with a narrow cowl it would easily allow a short pipe to an in-the-fuselage muffler setup, and an in-line twin would merely route the front header around the rear cylinder. There could even be functional "Stacks" on the side of the cowl, especially of the exhausts were on opposite sides of the engine.

No one seems to consider this when manufacturing engines. A 45 degree angled back cylinder could potentially have better flow into the intake ports as well, resulting in better power.

As for a "IMAC" style plane bias, these are the majority of planes that flat-twins are installed in, and also the largest segment of the flying public that have noise problems.

When the manufacturers STOP making the noise, silly, and totally archaic "cans" a lot of people now use, THEN somebody will finally knuckle down and get on the ball with quieter and better exhaust systems. The handwriting has been on the walls for a long time, that these exhausts are NOT a good idea. . both from a noise standpoint, and how much of a "public nuisance" problem they present to those who are not modellers. I give it 3-5 years before the old style "cans" are basically legislated out of existence from European-like niose restrictions.

What will you do THEN?? Complaining will be WAYYY too late, and those of us who have been pushing the envelope in this area will still be flying. ALL my planes are at 90-91 dB at 25', and about 96 at 9'. That's still too noisey, IMHO, and I have yet to see a warbird or "sport" gasser that was quieter.