News:


  • March 28, 2024, 04:15:07 PM

Login with username, password and session length

Author Topic: DO-335  (Read 1114 times)

Online John Rist

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2944
DO-335
« on: May 14, 2021, 01:45:46 PM »
Way back in 2014 at the Broken Arrow CL scale contest I flew my DO-335.  What brings this up is that I Just rediscovered a Youtube video of the flight.  The aircraft was scratch built from the 3-view drawing.  It featured a mid-engine design with a drive shaft to turn the back prop.  It was a lead sled and needed both engines running to fly.  I would adjust the fuel load so that the front engine would quit first.  Running on the rear engine it would land.  Without the front engine running the rear engine would over heat slow down and stop.  The was bad on the engine but yielded a neat taxi lap, slowing to a stop and engine turn-off.  Looked cool as all get-out.  Some day I may build a new DO-335 with the plan to increase the wing area and reduce the weight so that it becomes a good flyer. Any way enjoy the video.   y1  H^^

John Rist
AMA 56277

Offline Dan McEntee

  • 23 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 6824
Re: DO-335
« Reply #1 on: May 14, 2021, 02:58:02 PM »
  Way back in 2014!! I remember that. Have you test  flown it with a planned rear engine shut down first ? Did it tend to handle funny on just the rear engine? How about some details on the drive shaft? Just curious how you executed it. The first year we did that event I think Allen Brickhaus entered one by proxy, but I can't remember too much about it. A free flight rubber scale model with a front only prop for flight would really do well with all the rubber you could pack into that long fuselage. Nice model!
  Type at you later,
   Dan McEntee
AMA 28784
EAA  1038824
AMA 480405 (American Motorcyclist Association)

Online John Rist

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2944
Re: DO-335
« Reply #2 on: May 14, 2021, 08:08:08 PM »
  Way back in 2014!! I remember that. Have you test  flown it with a planned rear engine shut down first ? Did it tend to handle funny on just the rear engine? How about some details on the drive shaft? Just curious how you executed it. The first year we did that event I think Allen Brickhaus entered one by proxy, but I can't remember too much about it. A free flight rubber scale model with a front only prop for flight would really do well with all the rubber you could pack into that long fuselage. Nice model!
  Type at you later,
   Dan McEntee
I  did some rear engine quitting first test runs.  Didn't  mater which engine quit first with inline engines.  Prop shaft was built per my planes by Lee Machine Shop.  Drawing attached.  Used a 60 size boat U-joint on one end and a ball bearing on the other end.  Drawing attached.
John Rist
AMA 56277

Offline Dan McEntee

  • 23 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 6824
Re: DO-335
« Reply #3 on: May 14, 2021, 08:37:54 PM »
I  did some rear engine quitting first test runs.  Didn't  mater which engine quit first with inline engines.  Prop shaft was built per my planes by Lee Machine Shop.  Drawing attached.  Used a 60 size boat U-joint on one end and a ball bearing on the other end.  Drawing attached.

  Interesting. I was wondering if you used a solid shaft,  or a hollow shaft to keep weight down. And the shaft looks like it's dead straight off the engine. I was taught that on drive shafts with U-joints that you need a minimum of offset in the alignment so that the shaft would turn smooth. My experience was in printing press drives, and if you had any shudder or vibration anywhere in the drive line, it would show in the print as a slur. Did you find that you had to provide for that on this airplane? A single cylinder engine is enough vibration to deal with let alone something you may build in.. I think that is why some boats use a cable drive??  I wonder how that would have worked out for you?
  It looked pretty good on the lines and didn't seem like it was excessively heavy. What size would you shoot for if you started to build one tomorrow? Still use the same power plants?
    Thanks,
  Type at you later,
   Dan McEntee
AMA 28784
EAA  1038824
AMA 480405 (American Motorcyclist Association)

Online John Rist

  • 24 supporter
  • Trade Count: (0)
  • Admiral
  • *
  • Posts: 2944
Re: DO-335
« Reply #4 on: May 15, 2021, 11:12:46 AM »
  Interesting. I was wondering if you used a solid shaft,  or a hollow shaft to keep weight down. And the shaft looks like it's dead straight off the engine. I was taught that on drive shafts with U-joints that you need a minimum of offset in the alignment so that the shaft would turn smooth. My experience was in printing press drives, and if you had any shudder or vibration anywhere in the drive line, it would show in the print as a slur. Did you find that you had to provide for that on this airplane? A single cylinder engine is enough vibration to deal with let alone something you may build in.. I think that is why some boats use a cable drive??  I wonder how that would have worked out for you?
  It looked pretty good on the lines and didn't seem like it was excessively heavy. What size would you shoot for if you started to build one tomorrow? Still use the same power plants?
    Thanks,
  Type at you later,

   Dan McEntee
Right now the wing span is 24"  I am guessing the next one will be around 30". (No plans at this time to proceeded) The u-joint is out of a boat.  It is not a true U-joint like in a car drive shaft.  Its only purpose is to take care small misalignments.  When used in a boat the motor is tilted in line with the shaft.  To make a long story short it ran smooth.  I thought of using a flex cable but it complicated to prop attachment.   I must admit a hollow tube shaft with solid inserts on both ends would be a good thing.  By the way the biggest challenge was finding a source for the U-joint.  Most gas powered boats now use flex shafts. No U-joint required. Serious power boat racing is smaller than U-control stunt flying.   Parts are hard to find.

The other challenge is this airplane tends to be tail heavy. Took a lot of lead in the noise to balance.  Thus the bigger wing is needed to carry the weight.
John Rist
AMA 56277


Advertise Here
Tags:
 


Advertise Here