I just purchased a 1/3 scale Hanger 9 Cap 232 and I'm considering which engine to put on it. I'd really like to keep this plane as light as possible, so I'm considering the BME 110X. It sounds like a good strong engine, which is the lightest in its class, but I'm concerned about the single bolt prop hub.

I've been flying DA's and 3W's with the 6 bolt hubs, and I know they work great, but how reliable is a single bolt prop hub on an engine with this much torque?

Is the prop going to be slipping on me all the time?

I want to keep it light, but I don't want to have problems either.

Those of you with single bolt prop hub experience.......... Have you had problems?

Thanks, Jim

just watching the thread.

Read this thread.

[link=http://www.rcuniverse.com/forum/Video%2C_BME110X_Comp_Arf_40%25_Extra%25/m_1397961/tm.htm]http://www.rcuniverse.com/forum/Video%2C_BME110X_Comp_Arf_40%25_Extra%25/m_1397961/tm.htm[/link]

My friend Bill has had a LOT of problems with the prop slipping. The engine is very powerful, light and fuel efficient.

But unless you are planning to go bigger the ZDZ 80 is the best engine for the 1/3 H9 Cap and costs 1/2 as much.

Joe

Thanks for the reply.
The BME 110 weighs 3.9 lbs no mufflers.
The ZDZ 80 weighs 4.1 lbs no muffler.
Add in mufflers and the BME weighs just a hair more than the ZDZ only
because it has 2 mufflers.
I like twins. If I can get a twin with no weight penalty, that's a no
brainer in my book.

I'd like to hear from more people that have or have not had problems with a single bolt prop hub.
I'd also like to hear if you had a problem and found a fix for it.

Thanks, Jim

I have been running various BME engines ever since they were first produced and have yet to have a problem with the single bolt hub. I also ran a single bolt hub on my old 4.2 Precision Eagle glow engine and never had a problem with it either.

The BME hub is serrated and also tapped for 6-32 cap head screws. I insert the screws and then drill 2 holes in the spinner back plate just large enough to accept the screw heads. They keep the spinner back plate from rotating and since most spinner back plates are knurled and bite into the back of the prop, the prop doesn't move either when the nut is properly tightened. If you are using a wooden prop you should check the tightness of the bolt(s) regardless of how many there are as the wood can and will compress over time.

Len

Thats a BIG IF with the BME 110, unless you ordered one 4 or more months ago you will be waiting 6 months to get one. Unless you can find a store that has one in stock. Dons Hobbies had 3 , my freind bought the last one, He had waited 4 months for the 110 and was told by Kieth 2 months ago it would be 2-4 weeks, He still hasn't gotten it. Now when he gets called from Kieth that its ready he will probably pass so the next person in line will get it. Cheif dosen't have any and I havent heard of anyone that does.


Dont get me wrong, I like BME engines, I have owned 2, but getting a 110 is going to take patience and twice as much cash. Some people are saying the ZDZ 80 twin is as strong and lighter than the single. I bet there are a hundred H9 1/3 scale caps, sukhois and Extras out there with ZDZ 80 singles.

But its your money and your choice. Just my 2 cents.

Joe

I agree with you on wanting a twin. At least three times in my 500 or so flights on 33-35% twin engine aircraft, I've had a cylinder go out for one
reason or another. Each time I've been hovering. With a single I would've been out 4 grand with each outage. Just from a reliability perspective I
like the twin -- $12K savings for motors that cost $5-600 more.
One of the times a plug cap went out. If one went out on a single, thud. On one a spark plug broke due to vibration as a firewall was pulling loose, and on one a plug cap came off. Each time the engine had enough remaining power to pull out of the hover on a single cylinder.

On the prop compression issue -- it's even more of a problem with 6 bolt hubs. With a single bolt hub if a prop bolt comes loose, the prop spins. The engine dies and you may or may not lose your spinner cone.
On a 6 bolt hub if the prop comes loose, the engine will shear off all 6 bolts. Yes I've seen this happen. You lose the prop, the bolts, the spinner, and maybe the aircraft if losing all that sets your CG too far back to land.

Also, the choice of prop has a lot to do with this. Menz props tend to compress just a tad over the first 10-20 flights. With either a 1 or 6 bolt hub, tighten after every flight then every other flight for awhile. Once the Menz is done compressing, you will barely able to see the indentation in the wood.
I've seen some other wood props (sorry, I don't remember the brand) that will compress and compress and compress forever until eventually the prop washer works it's way so far in you can no longer tighten the prop nut (it's below the surface of the prop!)

Joe,

I have been on the waiting list for 14 months - and I am still on the waiting list. Whenever I call, I am told the middle of next month. I had an Edge built for the 110 Extreme - and ended up getting a DA and redoing the firewall. Yes, if I ever get the 110 I ordered, I will use it, but nothing gets built specifically for the 110 until I have it in hand.

Dan

I've got some other projects ahead of this one, so I can afford to wait a little while. I won't wait forever though.
It seems there are a lot of things in this hobby that you have to wait for at times. I always try and buy everything I need for a project well in advance (while working on other projects) so that I have it when I need it and don't have to wait.
These engines are not mass produced because there is not a huge demand for them like there is for other commodities. That is also part of the reason for the high price we pay for these engines. The cost of developement is only spread out over a few thousand pieces rather than spread out over 100,000's of pieces.

Anyway, let's get back to the subject.

I'd still like to hear from more people that have or have not had problems with a single bolt prop hub.
I'd also like to hear if you had a problem and found a fix for it.

Thanks, Jim

Any single bolt hub can slip if not tightened enough. I had an experience the other day where I installed a wood prop and thought I had it tight enough. When the engine fired the first time, it kicked back and I heard a distinct CLACK sound from the motor. Immediate inspection indicated the prop had indeed slipped and was resting against the cutout in the spinner. I took the cone off and re-tightened the nut, and it neverslipped again.

It CAN happen, especially if you do not get physical with the bolt. All that is preventing the prop from slipping is friction against the backplate for the spinner, which is not that great of a grabbing surface. An approch I have used extensively lately involves drilling the spinner backplate for the small 3W patter, using 2 holes to rest on the anti-rotation pins on the BME hub, and countersinking the otehr four holes on the back of the backplate, then literally screwing the prop down on the backplate using 1" x #10 fine thread screws. The heads fit into the countersunk area very well, and when the entire "piece" is bolted onto the front of the engine, and the holes engage on the anti-rotation pins, NOTHING moves!!!. I make SURE the center nut is as tight as possible, even after this little "fix", though, just to make sure. It's as solid as any 6-bolt setup out there when done this way.

Kris^. I had read on another thread where somebody drilled 2 holes through the prop and spinner backplate then glued 1/8" or 3/32" I forget pins into the prop which extended thru the spinner backplate. What's your opinion on this? It just seems alot easier to me.

I have an air models 26x12 on the front of mine. I cant get the nut real tight because I hold the prop for leverage and the spinner backplate and crankshaft turn when I try to crank down on the nut.

well. Now that I think about it. I like your idea more because with the prop jig you can duplicate the hole pattern easier if/when you change props.

I'm liking these ideas.
You could combine the two ideas.
Drill the small 3W/DA hole pattern, two of the holes are for the anti-rotation pins on the BME hub, then just use 4 pins in the other 4 holes between the prop and spinner backplate.
You don't even need to drill the holes all the way through the prop. Just drill from the back of the prop deep enough to leave enough of the pin protruding into the spinner backplate.

Thanks for the tips guys.

Jim

I have used the 102 and wood props for a couple of years now with prop slippage shearing the anti-rotation bolts just a few times ,probably dew to improper prop nut torque.This was not a big deal,but the 110 seams to be a different animal.With the 110 lets assume proper prop bolt torque,that has to be any first step.
I am using a Pete's spinner and may be a contributing factor because the back plate seams a bit slippery.I sheared the two 6-32 cap screws on first pop , with choke/ignition on couple times. Then tryed no choke/ ignition on ,and it did it again. I than increased the diameter of the cap screws to 8-32 with the same reaction. This time, not yet tested, I'm using a combination of Kris^'s and Tim_Indy's methods.With drill size set at the bolt dia.(not cap head size), using a four 8-32 bolt pattern,I've sandwiched a piece of adhesive backed sand paper(grit side toward back plate) between the hub and back plate.Than drilled 4 holes in the prop to except the cap heads and sandwiched a piece of the same sand paper (grit side toward back plate) and torquing the shi* out of the nut. I,m hoping for success this time.
Bill

Could a prop hub similar to the DA-100 be designed for the BME-110?

I have heard of someone custom designing a 6 bolt hub like the DA for the BME 110. I think it might be Kris^ in one of the posts above. Maybe he will let us know.

Jim

I saw the design Kris used, but it's not exactly like the 3W or DA design. Perhaps the hub isn't deep enough to do it like DA.

the piece I made for Kris^ is/was not designed to hold the prop on, it's a spacer to make the engine longer...It has the added benefit of keeping the prop from turning on the hub..Any hub can be drilled for 6 bolts if the hub is held onto a tapered crank with a nut, flush with the end of the crank....If the 2 anti-rotation bolts used on a single bolt hub are big enough and kept tight there's no reason they would ever shear off anyway...TIGHT is the operative word on any hub....

Believe me these bolts were tight. They had been cranked on not more than 3 minutes before they sheared and the center prop nut was cranked and double nutted. When the BME backfire it sheared both 6-32 bolts, broke the spinner and threw the double nuts. The 5/16 prop nut and locknut had just been tighten using 8" wrenches. Loose hardware and prop compression are NOT the problem.

Joe

I run all engines on my test stand using only two of the six 5mm bolts on any six bolt hub..Only prop I ever broke happened when the 2 bolts had bottomed out in the hub and the prop felt tight but wasn't....I run 3W 150 twins all the time.....Usually if an engine backfires it's out of time or Waaay lean......Or the ignition battery is low......
All my test props are wood, a 30-10 or a 28-12 for the biggies and a 26-10 for the smaller ones....and I ALWAYS stand behind the engine.....

I do similar to RCIGN1. I run only 3 of the 6 bolts on my DA-100 in the air. The bolts weigh 1/3 of an ounce each, going from 6 to
3 saves an ounce!

Backfires will kill anything. Often, the first backfire loosens the prop nut or compresses the wood, making way for the second to destroy things. Always tighten everything up after a backfire then fix the problem that caused the backfire before starting again.

This is a new engine, I am thinking it may be timed wrong or perhaps the 110x timing is more agressive than other twins. The damage occured on the First backfire.

Joe

Need a delete key

Did anyone consider that the backfire occured as a result of a loose prop?
Typically the engine pops -then the flyer says uh oh- and when checking, finds that the prop is loose.
Conclusion is that the backfire caused the looseness - not the other way around.
Apparantly there are a shi-load of opinions as to how to best affix aprop but when all is said and done - what matters is clamping tension -it must exceed any rotational loading.
Our two stroke engines rely on an absolutely solidly affixed flywheels - in order to start and run -
I have NEVER had one of my gassers backfire -
had em fire out of phase - with a "whoosh" from the exhaust -.
On the glo engines we all learned to love/hate -the loose prop (single bolt typically) a loose prop always resulted in popping and a failure to start.
( Also, overcompressed 4 strokers were particularly notorious for this .)
On a lawnmower - early type with no indexed blade - these suckers would never start with a slightly loose blade.
Our engine ALWAYS fire just prior to TDC- which results in a sharp kick--if the prop is loose --otherwise -- the flywheel weight of the prop or blade, carries on thru and we get the happy putt-putt noise.
If the ignition is improperly setup - one can get kicked on the hand - but my gassers from 40 to 210 and all sizes in between act the same way.
I would appreciate any additional input on this.
(even ranting and raving )

If the ignition is out of time it could fire after TDC, hard on your hand...If it's way too far advanced on the static timing the electronic retard won't go far enough, so you get a kick when starting...a properly timed engine can be started with one finger without fear of kickback....
And TIGHT is the operative word...If the 6 bolts are bottomed out in the hub they feel tight, but the prop isn't, and the bolts shear....Been there, wrecked a 30-10 prop in about 2 seconds and sheared off the bolts..
The direction of rotation tends to keep a single bolt tight when the engine is running, so unless the engine starts running backwards the prop stays on when the 2 anti rotation pins shear....
This is why I like single bolt hubs, or 6 bolt hubs with a big single bolt in the middle...
Our race engine did this, the 1/4-20 anti rotation bolts sheared, the 3/8-24 center bolt kept the prop on....

Well,
I've decided to give the BME 110 a try. There are a few people that have had problems with prop slippage, but I've heard from a lot of people that have not had problems also. The weight savings is too tempting too me, so I'm gonna give it a try.

I was able to purchase one already after only a week of looking for one. A nice guy told me there was one left at his local hobby store and I'm jumping on it! I just thought I'd let you guys know in case anyone else is still waiting/looking for one. There are some out there. Just ask around and look around and maybe you'll find one too. It sounds like the waiting list may be getting short by now also, so even if you have to wait on the list, hopefully it won't take too much longer.

Thanks for all the input here.
I'll let you know if I like it or not.

Jim