RE: BME 115 Any Field Reports?  
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RE: BME 115 Any... - 12/7/2007 8:00:25 PM   
Truckracer


 

Posts: 665
Joined: 4/3/2004
From: Des Moines, IA, USA
Status: online
quote:

ORIGINAL: Pat Roy

Taking off at idle rpm is another consideration. You have to be able to slow down enough to lose lift for landing, and the Cub wing provides a lot of lift at very low speeds.


Its all a matter of idle speed and prop pitch ... just like any other airplane. It will come down! Remember, a big CUB also has an incredible amount of drag. I would worry more about engine weight in a CUB ... seems like it might need more nose weight than the 115 would provide.

5 Cubs in my model shop ...... everybody has to have at least one big CUB!


(in reply to Tired Old Man)
       Post #: 951

RE: BME 115 An... - 12/7/2007 8:37:46 PM   
AmpAce


 

Posts: 81
Joined: 5/22/2006
From: Flyer's Paradise, USA
Status: offline 		Thanks for the input, guys!

Altavillan, deep down, that's what I'd like to do. I think I can make it work.

Pat Roy, I do have the same concerns, and have been told the same thing by others. I've even thought of setting the throttle stop down to where it would be safe, and still have plenty of performance. My Super Cub will be very draggy. It will hopefully, (if I can find a suitable setup), have 10" tunra tires, and unfaired gear struts, working flaps, etc. According to the spec's the 115 will idle down to a lower rpm than most other motors. I have no idea if that spec holds up in real world use, though. With a 8" or so, pitch prop, it shoud come down, if the idle will slow down decently. Another concern is overheating and/or going over rich at part throttle. I plan to do some baffling inside the cowl, and am hoping I can tune the over-richness out of it, at least to the point that it will run smoothly without wanting to quit in flight.

Truckracer, I think you are right. One question is whether the 115 can be made to idle slowly enough, reliably. Since the Cub won't be a speed demon, I should be able to use a fairly flat pitched prop, especially at that length, which replicates a "climb prop" for a real Super Cub. If I can get the rpms down, the larger prop will provide even more drag, with the throttle closed, due to the larger prop disc. As for tail-heaviness, I am looking at some ways that I can lighten up the tail, without sacrificing strength. My tundra tires will add some weight, and make it fly nose-heavy due to the added drag down there, so maybe I won't have to add too much weight to the nose. I always hate doing that!

Thanks again, guys, and keep the input coming.

AmpAce

(in reply to Truckracer)
       Post #: 952

RE: BME 115 Any... - 12/7/2007 8:39:24 PM   
R.C. ROB


 

Posts: 98
Joined: 4/27/2006
From: pinetop, AZ, USA
Status: offline
quote:

ORIGINAL: PATRICKP


Here is a engine that Rob says has always run perfect.

What we all need to know is why some/few, very few, run so well and all the others don't.

We all would like to know what you have as far a carb and exhaust system on this unit.
it is a 115 engine right?

How can so many have issues an some have no problems.

Your at 6000'

Ham can't make his run well even @5000.
what is up?

Do most of us suck at tuning?
I DON'T THINK SO!

Look at the huge amounts of posts and issues around the 115, it's every where.
1000's of posts.

1000's of hours and 1000's dollars in lost equipment and lots of people trying to fix this.

Tell them all how yours runs so well from factory.

Even the ones's who say are runing well do have some issues of some kind and have made changes.

What is wrong with the rest of us?

Rob,
mine works that great too, but it took a lot of work, a huge amount of work and
the kit I designed manufactured and installed after the carb to get it there. ( knife edge or inverted loss of rpm)

Please advise all your carb# and exhaust system design for all the others to see.

They need to know how you have successfuly made this 115 work great.

Patrick


PATRICKP
Yes it is a 115.
The enging has always run great. When I first fired it up it was a little rich. before I even flew it I turned the hi in about 1/8 of a turn and the prop riping noise was unbelivable so I decided to fly it. It had a slight hesatation on a quick transition from idle to full so I turned the lo out 1/8 ond it was perfect. the nedles are a little touchey.I knew when I was knife edging just off idle it was gowing to be a good one. I have stock BME mufflers and my carb says WB25 825. My reed block is "1 1/4 long and there is a spacer under the carb that is 3/16. Just the way it came stock from BME.I brought it down to pheonix to see how it ran at low altutude and all I can say is wow! talk about power. I knew nobody would belive me here unless you saw it for yourself. So I have a witness, look at bzyguy01 responce on the (BME service)forum post # 24 that is my sukhoi he is talking about. I thought it was eazy to tune but I have been messing with engines most of my life. I have worked in engine machine shops mostley aircraft, started r.c. racing as a teenager and curently race in the unlimited scale racing associaion.









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(in reply to PATRICKP)
       Post #: 953

RE: BME 115 An... - 12/7/2007 8:50:02 PM   
Truckracer


 

Posts: 665
Joined: 4/3/2004
From: Des Moines, IA, USA
Status: online 		AmpAce ..

What plans are you working from for your Super Cub? Or is it a kit?

One of the nicest ones I ever watched fly was a Balsa USA Super Cub with a large 3W twin. Don't remember exactly which 3W it was ... but over 100cc and it fit well in the cowl. This guy was a good 3D pilot also and really made that CUB talk ... then would slow down for the scale part of the show. Kind of a split personality sort of airplane.

Don't forget to watch the prop speeds when you go for those large diameter, low pitched props. Very easy to overspeed them .... especially with something like a 115 up front. I agree, you should get quite a bit of braking from these.

(in reply to AmpAce)
       Post #: 954

RE: BME 115 An... - 12/7/2007 8:55:01 PM   
R.C. ROB


 

Posts: 98
Joined: 4/27/2006
From: pinetop, AZ, USA
Status: offline 		AMPACE
Dont wory about the idle. It will turn so slow you wonder how it is still running. but watch out the throttle it verry touchey. This thing will make some instant power with just a blip of the throttle.

(in reply to AmpAce)
       Post #: 955

RE: BME 115 An... - 12/7/2007 9:26:37 PM   
altavillan


 

Posts: 1236
Joined: 10/24/2004
From: Altaville, CA, USA
Status: offline 		Hey Ralph ?? Since you just aquired a new 3W 106 CS does it have the new carb/reed block? Have you looked inside to see what they did? The new ones have an aluminum mounting plate.

_____________________________

I didn''t put the bullet in the fire and you quit talking about my mother! "Cosby, Shop Class, 1968 or so"

(in reply to R.C. ROB)
       Post #: 956

RE: BME 115 An... - 12/7/2007 9:38:14 PM   
RTK


 

Posts: 4089
Joined: 4/20/2003
From: CENTRAL , CA, USA
Status: offline 		You know I could not resist looking inside Yes it has the new aluminum block
The new reed block has one straight side and the other angled in, reducing the open area of the block. The reeds are also slightly angled to fit into the new wedge shaped area.

(in reply to altavillan)
       Post #: 957

RE: BME 115 An... - 12/7/2007 9:54:44 PM   
AmpAce


 

Posts: 81
Joined: 5/22/2006
From: Flyer's Paradise, USA
Status: offline 		Yes, mine is a Balsa USA kit. I'm adding the scale ailerons and flaps. Glad to hear that you saw one fly really well. Maybe there's still hope for me! I've heard lots of good things about 3W engines, but just can't find one that will turn a 27-28 inch prop and still fit in the cowl. Same with most if not all of the singles, they have to be mounted inverted, and the cylinder head still has to stick out the bottom of the cowl.

I just have to believe that a BME 115 can be made to work, even if I have to modify the throttle stop, or adjust the end point on my radio. The 115 is small and light enough despite it's power and displacement. It just wouldn't have to work as hard in the Cub.

AmpAce

(in reply to Truckracer)
       Post #: 958

RE: BME 115 Any Field Reports? - 12/7/2007 10:12:38 PM   
rcpilot47


 

Posts: 5
Joined: 2/9/2002
From: Wayne, MI,
Status: offline 		Has anyone been in touch with BME??? I have been trying to for the last 3 months via phone & e-mail with no results. I need to purchase some gaskets and baffle for a 110 Extreme and a ignition for one of me 44's

(in reply to RTK)
       Post #: 959

RE: BME 115 An... - 12/7/2007 10:14:42 PM   
RTK


 

Posts: 4089
Joined: 4/20/2003
From: CENTRAL , CA, USA
Status: offline 		AmpAce--As long as you are not doing a lot of rolling maneuvers and KE (which I don't think you would) the 115 will work great. Baffle it like any other engine and over heating will not be a problem. Dead sticks should NOT be an a problem either.

rcpilot47--Keith is MIA as of late, hopefully that will be resolved shortly.

(in reply to AmpAce)
       Post #: 960

RE: BME 115 An... - 12/7/2007 10:18:40 PM   
rcpilot47


 

Posts: 5
Joined: 2/9/2002
From: Wayne, MI,
Status: offline 		Thanks... So much for product support

(in reply to RTK)
       Post #: 961

RE: BME 115 An... - 12/7/2007 10:20:03 PM   
Tired Old Man


 

Posts: 12356
Joined: 2/25/2002
From: Central, CA, USA
Status: online 		Ralph,

You didn't tell me you picked up a 106. Now both of us have one?

Back to the Cub. Unless it's a Zinger or similar I would think it might be difficult to locate a flat pitch like a 6 or an 8 in a 28" diameter. Most of the prop manufacturers like to make the pitches in roughly half the diameter.

_____________________________

If you can''t fix it with a hammer, you have an electrical problem.

(in reply to AmpAce)
       Post #: 962

RE: BME 115 An... - 12/7/2007 10:37:02 PM   
RTK


 

Posts: 4089
Joined: 4/20/2003
From: CENTRAL , CA, USA
Status: offline 		Very Long story Pat. At least I can say I have owned just about every manufacturer out there

(in reply to Tired Old Man)
       Post #: 963

RE: BME 115 An... - 12/7/2007 10:40:14 PM   
Tired Old Man


 

Posts: 12356
Joined: 2/25/2002
From: Central, CA, USA
Status: online 		I'll loan you a Brison to complete the circle I still have to pick up a Brillelli when he gets that new twin on the market.

_____________________________

If you can''t fix it with a hammer, you have an electrical problem.

(in reply to RTK)
       Post #: 964

RE: BME 115 An... - 12/7/2007 10:44:44 PM   
RTK