Go Back  RCU Forums > RC Airplanes > Scratch Building, Aircraft Design, 3D/CAD
Reload this Page >

ME 329 engine placement problems

Notices
Scratch Building, Aircraft Design, 3D/CAD If you are starting/building a project from scratch or want to discuss design, CAD or even share 3D design images this is the place. Q&A's.

ME 329 engine placement problems

Old 02-04-2004, 04:38 PM
  #1  
ptulmer
Senior Member
Thread Starter
My Feedback: (5)
 
ptulmer's Avatar
 
Join Date: Apr 2003
Location: Brunswick, GA
Posts: 4,867
Likes: 0
Received 0 Likes on 0 Posts
Default ME 329 engine placement problems

I am designing an ME329. One problem that I have run into is the placement of the engines. I have attached a pic of the planform. It will have two pusher motors sticking out the back. I will need to position the engines about four inches further forward than the trailing edge.
In other words if the engine is about 4 inches long then add a 4 inch extension to put the engines closer to the cg. One thought was a motor mount that extended past the front of the crankcase and had a bearing at the end, then I would just need a rod attached to the crank. Right?[sm=confused.gif][sm=confused.gif] I can't find any commercial examples an that makes me wonder if it is feasible. Any other ideas?

ps. two .90 four strokes! Nice big plane!
Attached Thumbnails Click image for larger version

Name:	Vt56136.jpg
Views:	12
Size:	18.0 KB
ID:	97363  
Old 02-06-2004, 11:10 AM
  #2  
ptulmer
Senior Member
Thread Starter
My Feedback: (5)
 
ptulmer's Avatar
 
Join Date: Apr 2003
Location: Brunswick, GA
Posts: 4,867
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ME 329 engine placement problems

?huh? No ideas?[&o] Are there no examples because this is not possible using current level of tech?

click here for a pic of the plane-- http://www.luft46.com/jgart/jg329-6.jpg

You see why I want to make one of these!
Old 02-06-2004, 01:58 PM
  #3  
FHHuber
Banned
 
Join Date: Jan 2003
Location: gone,
Posts: 4,923
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ME 329 engine placement problems

The problem comes from the long shaft needed. If the scale of the model was smaller... you could go with a drive shaft out of a model boat, clipped to the correct length. However... I don't know of a heavy enough boat drive for use with the .91 4-stroke.

The needed length is too long for trying just a shaft extension. You need a universal joint and drive shaft... or a gear drive to allow the shaft to "float" in relation to the engine crankshaft. a tiny shaft misalignment at the current prop hub would get amplified excessively over the 4 inches and would lead to a warped shaft... possibly destroying the engine. (and the airplane)

Actually... the gear drive may be the way to go... a single pair of gears would reverse the rotation allowing use of a standard prop instead of the pusher props, which are harder to find in any given desired pitch and diameter. (and pusher props are more expensive)
Old 02-06-2004, 07:36 PM
  #4  
Flypaper 2
Senior Member
 
Join Date: Mar 2002
Location: Kingston, ON, CANADA
Posts: 4,925
Likes: 0
Received 3 Likes on 3 Posts
Default RE: ME 329 engine placement problems

Drive shafts would be the way to go, but the firing impulses would put a large torsional load on the shaft. It would have to be a solid shaft as the universals wouldn't be able to take it without a flywheel on the engine, to help smooth out the impulses. Would be an ideal setup for electric drive. Motors will run either direction, no impulses. the light weight Li -Polly batts have made electrics a whole new ball game, although they both have their place.
Old 02-06-2004, 07:52 PM
  #5  
BMatthews
 
BMatthews's Avatar
 
Join Date: Oct 2002
Location: Chilliwack, BC, CANADA
Posts: 12,425
Likes: 0
Received 22 Likes on 19 Posts
Default RE: ME 329 engine placement problems

If you insist on using engines instead of electrics for this then I second FFHuber's idea of a gear coupled extension drive. The combination of the gear acting both as a reversing and flex element at the same time is a clever bit of inspired brilliance. Good on ya FFH [8D]
Old 02-07-2004, 12:22 AM
  #6  
ptulmer
Senior Member
Thread Starter
My Feedback: (5)
 
ptulmer's Avatar
 
Join Date: Apr 2003
Location: Brunswick, GA
Posts: 4,867
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ME 329 engine placement problems

Thanks guys. I know it's crazy to try to use an engine when the solution to all my problems is simply to go electric. It just seems like a shame to go to all the trouble to build such a warbird and then you take it out to the field to fly it for the first time and someone says "well...it's quiet" That ought to get me in trouble with the electric guys.

I'll try to put my thoughts in order here. My original thought was to attach an extension directly to the crankshaft and run the extenstion through two bearings before the prop. I was worried about torque to the crank itself. Adding a universal would be fairly easy, but that doesn't solve the crank problem. (because it is the weakest link) The gear drive is the most appealing because you can gear down and swing a larger, more scale prop. And the gear reduction will solve the torque problem. Only one problem...gears are pretty high-tech. I have no idea where to get what I would need. I'll start looking and thanks again for the advice.
Old 02-07-2004, 02:37 AM
  #7  
FHHuber
Banned
 
Join Date: Jan 2003
Location: gone,
Posts: 4,923
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ME 329 engine placement problems

ORIGINAL: BMatthews

If you insist on using engines instead of electrics for this then I second FFHuber's idea of a gear coupled extension drive. The combination of the gear acting both as a reversing and flex element at the same time is a clever bit of inspired brilliance. Good on ya FFH [8D]
Comes from working on geartrains for 60,000 shaft horsepower Turbines. Lots of BIG gears to play with.

You may note my mention of the boat drives.... they always have a big brass flywheel in the kit.
Old 02-26-2004, 05:43 PM
  #8  
Tempest-RCU
My Feedback: (98)
 
Join Date: Jun 2002
Location: Gaithersburg, MD
Posts: 240
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ME 329 engine placement problems

I would agree that this aircraft is a good candidate for electric power. In fact, just today I came across the design on the Luft '46 site and it got me thinking about developing an electric powered version.

Just out of curiosity, have you managed to find any other 3 views than the ones on the Luft '46 site. I am looking for something that gives a better sense of the fuselage and wing cross sections.

Thanks and it sounds like a great project!

Paul
Old 02-26-2004, 06:44 PM
  #9  
ptulmer
Senior Member
Thread Starter
My Feedback: (5)
 
ptulmer's Avatar
 
Join Date: Apr 2003
Location: Brunswick, GA
Posts: 4,867
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ME 329 engine placement problems

You can actually fly it in MS Flight sim. Here's a link to get it-- http://www.simviation.com/fs2002military4.htm (last two on the page)

Luft46 is the most comprehensive. If you missed the pictures this is the link-- http://www.luft46.com/jgart/jg329.html
There was also a second 3-view. Sorry if I'm just telling about what you already saw.

I have already developed the basic planform and ribs using compufoil. If you want the .dxf files just say the word. I was going to make formers to slip over the top and bottom to shape up the fuse and engines. It would have been a very easy and very cool glow powered plane. I'm still considering if I want finish it.
Old 02-27-2004, 08:16 AM
  #10  
Tempest-RCU
My Feedback: (98)
 
Join Date: Jun 2002
Location: Gaithersburg, MD
Posts: 240
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ME 329 engine placement problems

Sure, I would love to have your .dxf files! What airfoils have you used for the wing?

You can send the files to me at [email protected]

How were you going to shape the formers? Have you purchased any of the available plastic kits? I was thinking of getting one to use for cross sections.

Once again, thanks for your help!

Paul
Old 02-27-2004, 10:34 AM
  #11  
ptulmer
Senior Member
Thread Starter
My Feedback: (5)
 
ptulmer's Avatar
 
Join Date: Apr 2003
Location: Brunswick, GA
Posts: 4,867
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ME 329 engine placement problems

I have made a zip file including all the pics and dxfs. I was using 3-views converted to vector for cross-sections. I even included the.lft file I made with compufoil. Anyone is welcome to it and if you want to share your results I would be like to see where others take this project. I will be getting back on it if I figure out a good way to put a four-cycle engine on it.

here's the link- http://www.ulmer-rc.com/Me329.zip

Tempest,
I was going to use the .dxf's of the converted 3-views for the formers.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.