I just hung up the phone after talking with Keith Baker at BME. They are just finishing the last run of 102 Evo twins before starting to set up to produce the 110 Xtremes, and expect to be producing the 110's very soon. Of interest, though, is the information he gave me concerning the first prototype 55cc single "Xtreme" that they have begun testing.

Initial power and tractability look VERY promising. The prototype is using a modified crankcase from the current 50cc engine, with the cylinder and new style crankchaft adapted to the casing. The motor uses a side reed valve arrangement, rather than rear or piston ported induction. At this time, crankcase volume has not been optimized, being still about 10-15% larger internally than the final crankcase will be, and the motor weighs 2lbs 2 ounces bare. CAD generated crankcase design shows a drop fo 2-3 ounces of overall weight, as well as increased efficiency due to reducing internal volume and making the motor properly optimized.

Initial power is, unexpectedly, VERY much more than anticipated. With 10 minutes of run time the little 55cc motor turned a consistent 7800 rpm at max power with a Mejzlik 22-10 prop. This is a motor that is NOT broken in, still using an improperly fitting crankcase, and run fully warmed uo.

A corellation of power to a Menz-s 22-10 would be about 7500-7600 rpm right out of the box. This is on a stock muffler, NOT on a pipe setup. Keith went on to say that after they get the crankcase design finalized, they expect to have under 2 lbs final weight, and 2-300 more rpm for max power.

Imagine that. . 2 lbs. . 7800-7900+ with a Menz-s 22-10, close to 8200 with a Mejzlik 22-10, and God only knows how strong with a 24-10. . .(probably very close to 7000)

Seems to me that the 27-30% planes will have a new engine to power them soon.

My BIGGEST problem is that I have ordered two of them and he keeps puching them back.....hopefully the wait will be worth it.

I have two on order as well .. more than worth the wait I think

Hey Kris^,

Keith didn't happen to say how the mounts were going to be did he?
Side reeds (not trying to compare) kind of like what 3W uses?

I hate waiting for new engines to be released

be kind of hard to have rail style mounts with a side-reed valve and side exhaust. . expect to have a rear mount of some sort, or a midified beam mount.

easy kris^ , didn't expect it to have beem mounts either.

Mark my words"2 lbs. no way! WONT HAPPEN WITHOUT ALOT OF SHAKKIN"

Darin

Kris,
Did Keith mention a price on the extreme 55??

whats the price on these? im also curious to know

FYI: the OS 120 stroker is 2 pounds (32oz). It will be interesting to see the long-term reliability and durability of this engine, which is clearly pushing the limits of what metal can stand up to. Besides, so many planes in this size range need nose weight anyway, so why risk using a new engine that hasn't proven itself when you might just have to add more lead up front anyway?

MOUNT.......

Several months ago when I was talking to Keith about this he said it would come with some sort of radial mount, so it will be a rear mounted engine.

PRICE.......

Here again when I spoke to Keith, he said it would be the same as the old 44 and the newer 50------>$499.99 WITH THE MOUNT

Sounds to me like CAPtain232 has it straight. The price should not change, and the motor (from previous conversations with Keith) will come with a radial mount, similar to the one on the current 102 and upcoming Xtremes.

The challenge, considering this is nothing more than a 110 with only one cylinder, is to reduce internal crankcase volume without adding extra weight. This will require a redesign of the rear crankcase half, with a 'shifting around" of metal to use the radial mount, but also fill in the voids inside the crankcase that would cause less efficiency.

Some of the ideas being floated around to reduce weight will be directly related to tremendously over-designed areas of the engine. Currently the 55 uses the front of a 110 crankshaft, yet produces substantially less power, so this area can be lightened and smaller bearings can be used. This would also allow for less mass on the crankcase itself, so you can see the possibilities for further weight reduction.

If you look at a DA50, it appears to use the same crankcase front as the DA100. This is a VERY beefy piece, with absolutely huge bearings. Keiths approach is to reduce the mass of these parts while still using the highest quailty bearings and materials to ensure longevity.

On a comparison note with the YS120. . this motor DOES use a sleeved cylinder, right? Those cylinders do weigh a bit, and the fact that you have to make the outer cylinder over-sized to accomodate the liner adds weight to the total engine. I imagine that if you used a linerless cylinder, as BME does, with nikasil plating, you could reduce the weight of the YS by 4-5 ounces by not only tossing the liner, but making the overall cylinder dimensions smaller. Then you have the separable head, which adds weight for bolt bosses and bolts and for the mating surfaces between the head and cylinder. Make it a one piece head and there would be a further weight reduction.

Really, because of the way the YS is designed and put together. . it's a BIT porky. I bet slicing the beam mounts off the crankcase would save 2 ounces or so, too. You STILL have to use a motor mount. . so attaching a small radial mount on the back, to the backplate screw holes, would allow you to use a SMALLER mount, toss the beam mounting ears, and further reduce the engines weight.

So, you see. . . the vaunted YS120 is NOT that light, and has a TON of extra metal on the engine. I bet 4-6 ounces could be pulled off the assembly without even blinking hard, and no longevity or strength would be lost, and then your motor mount would be another 2-3 ounces lighter than the currently available pieces. Gee. . we just saved HALF a POUND!!! That would put the YS in the 25-26 ounce range. . . a bit lighter than the projected weight of the BME 55 Xtreme.

So, you see. .under 2 lbs is entirely possible and achieveable, with no sacrifice of strength and longevity.

Is that 2 lbs ready to run weight? No way! If youre going to compare that weight to a YS 120 or anything else for that matter you have to add the mount, ignition, battery hub and bolt (s).

Okay, lets add in 6 ounces for the YS MOUNT!!. . then compare that to the ignition and battery for the 55.. hmm bout the same. .

the 55 is 2 lbs WITH the backplate mount. . . add in 6 ounces for ignition and battery, the engines weight is WITH sparkplug and prop nut/washer (BME has always weighed the engiens this way)

Soo . lets see. . .a YS120 WITH mount is 2.5 lbs. . a BME55 WITH mount, ignitiona nd battery, is 2.5 lbs. . . . fuel load is the same. . . power is DOUBLED. . . mufflers are about the same weight.

OOOOPS. . forgot. . the BME takes a MUCH larger prop. . hate to see a poor YS120 trying to swing a 22-24" prop. . probably break something or melt it down from overheating

Look at it THIS way. . EVEN if the BME came out 3-4 ounces heavier overall, it's making DOUBLE the power of a YS120, swinging a 4-6" larger prop and making 75-80% more thrust. . . . and the cost is not that much more. . .

sounds to me like the YS120 faithful are about to get a revelation.

Please add my name to the list of skeptics. When I see a copy of that motor sitting on a digital scale then I'll beleive. My suggestion for effective proselytizing on behalf of the 55 extreme now is to concentrate on the Amsoil faithful, because those guys will believe anything.

Lets make sure this is clear because I don't like to put words in anybodys mouth especially when they are ridiculous. Your assertion is that a BME55 on pump gasoline is going to produce double the power of a YS four stroke, the current model would be the YS140 limited as the 120 is NLA, running on YS's recommended fuel, 20-30% nitro methane in methanol. For the record my example of that engine weighs 32.3 oz and will turn an 18-12 8100 rpm static. FYI YS known for being conservative rates that engine at 2.9 BHP.

I am not an engine jock.
I will say that when small engines went from cast iron to cast aluminum there were problems and people said a lot of negative things. Now with the steel sleeves in the aluminum block, you get lots of power for the weight. I think time will tell and these new engines will making gas flight available to more and more people.

Super]

I'm sorry to hear you are getting such low power numbers, especially considering the large amount of nitro (20-30%!!!) from an engine that weighs over 2 lbs. .

Maybe you should step up to a BME55 and swing a 4" larger prop at the same rpm, on gas. Or, perhaps, add a tuned canister muffler and add another inch of propellor at the same rpm??? or add a 3-bladed prop on top of the canister muffler and be quieter than any pattern plane out there with almost double the thrust???

It would seem that you are disappointed. Perhaps a change to gas is in your future.

worse case scenerio
2.2 lbs bare
add 4 oz batt
add 2 oz ignition
add 2 oz spark plug and ignition switch
add 7 oz pitts muffler

Thats still only 3 pounds completely ready to fly. on a 80 to 86 " airplane this will be an absolute monster
Im thinking extreme flights 85" yak 54 and the bme 55 for next years christmas present

The only problem I see is CG issues from it being too light

Most of the planes designed for 50 cc engines need a 3.5 4 lb engine to balance.


epc

I fly both already. I'm just not much for stupid claims about weight, power, or otherwise. I will say you are the perfect salesman for Baker and his massively overpriced piston port cylinders on reed crankcase engines. Your claims are so outrageous they make the BME factory claims almost believable. As for the peformance of the YS140 mine will hit 106-111 mph on my Stalker in level flight in 70 degree weather which is around 10,000 rpm with that 18 x 12. As for the prop diameter anything larger would be a prop strike waiting to happen on the pattern airframe I'm flying it on.

If you can get one of these engine to run for several hundred hours, then I'll start believing.

Again, my new Extra needed nose weight with a Brison 3.2 on. My buddy's H9 Sukhoi needed 2 lbs nose weight with a ZDZ 80. Where is the advantage of pushing to get the engine so light when it may not be necessary?

Design the planes to be lighter.......It can be done without loosing strength in the frame.....result a better performing 3D plane......

That is what this is all about really....Trying to get the smaller planes to perform like the 33 and 40% planes....No they will never be exactly like the big ones, but getting closer.

Take a 120 size CAP or EDGE or EXTRA and put this 2 pound engine in it, or let's say it weights 2.5 pounds, you have lost nearly 1 full pound over the same plane with the current 50cc engine. My H9 1/4 CAP weighs 13.75 pounds with the BME 50, if I can get that down to 12.75 or an even 13lbs. it will fly a TON better.

I really fail to see the correlation of a "speed" claim. While 106-111 mph may be an admirable velocity, it does absolutely no good if the plane can't maneuver, which is what the whole exercise of lightening the BME engines is all about. Reducing aircraft weight, as well as getting as much weight out of the "ends" of the plane as possible, is all aimed at making the plane more aerobatic and responsive, not to make it an unguided missile.

If your YS flies a "Stalker" at that speed, then it realy does not need any more motor, does it. But, if you are flying an IMAC 30% plane, and can get it lighter in the nose and tail so that it responds and flies better, then you have just achieved something. going to a lighter engine is the first step in that progression to a better flying aircraft. This is where the BME enignes excell.

NOW. . if you REALLY want that Stalker to haul boogie. . . go get a 20-18 THREE blade (so you have enough ground clearance) and bolt the BME on it. . I guarantee you'll see the high side of 130 very easily.

Personally, I can't see the logic in a plane that goes over about 60-70 mph at any time, unless you are pylon racing. Much above that speed range and its here and gone too fast to have much fun with. BUT. . take an 80-85" aerobatic plane with a very light but powerful motor on the nose. . now THERE is where the fun begins.

Below are the actual typical weights of the misc. components required to run the BME-55 or anything in this size range.

2.0 ozs. Aluminum CNC radial engine mount
3.7 ozs. C&H Auto Ignition unit
1.6 ozs. sparkplug
5.2 ozs. NiMH 4-cell with switch
7-9.5 ozs. Pitts style exhaust cannister.

19.5 to 22.0 ozs. or 1lb.- 3-1/2 ozs to 1lb.-6 ozs. plus the bare engine weight.

Extreme 55's percieved weight of 2lbs-2ozs + 20ozs = 54ozs.

I have owned several BME engines they all weighed pretty close to the advertised weight stripped, less sparkplug, ignition, prop-bolt(s) and of course engine mount.

So the NEW Extreme should weigh in about 3lbs-6ozs. all up. Average lighter weight as compared to other engines in this size that are considered lighter engines will be around 10ozs.

Past BME engines have never been known for their lack of vibration, properly tuned or not! If this little guy makes the purported power at the suggested weight without beating itself/model up it will be another winner from BME...