Vance W Jaqua wrote:

  This is where a reduction drive with offset from the engine centerline
  provides a benefit, Each inch of offset buys you two inches of prop
  diameter. - (Gee! would this make an EZ in side profile look like
  the famous BD5?)   :)   - Vance

Good idea. Get one of Ken's tried and true 3:1 cog belt reduction units and have
Ken lengthen the output shaft by about a foot. Ken could use something like this four
inch output shaft without the planetary to stiffen the output shaft in torsion.

That will make one hell of a pusher PSRU. Could help with the prop-in-wing-wake
problem.

Paul Lamar

 At this time the EZ's and the like have no pitch change under power, one of the really bad characteristics of the
 'viggen,
 which
 I believed lead to more than one crash.
 Canards are very pitch sensetive to begin with. If moving the C/L of the engine up to use a bigger prop or get more
 ground
 clearance was a no brainer they'd all be doing it anyway.
 ...Chrissi

You can't extend the gear and you can't raise the thrust line so Burt
has designed you into a box.

Well you will just have to bear the canard cross then.

Paul Lamar

Paul, Think of the profile differences between the 13B and the Lycoming. The 13B and Tracy's redrive is about the same
overall
length but you don't have the bulk of the Lyc to deal with. Just a nice small diameter redrive and an extension can increase
the
length by 4, 6, or 8 inches. I'm putting my effort into the arrangement of components so I can take advantage of that small
profile when I get ready to make a new cowl. That's where some real improvements can be done aerodynamically to improve in
feed
airflow to the prop. MHO.

Rick

Rick Girard

Well as Chrissi pointed out if you move the prop aft you risk prop strikes.
If you use a 2.17:1  PSRU and go down on the prop dia. to run it at 3600
the engine will run at 7800 RPM. More HP. Doable I guess. What diameter do you need
to run the tips at .8 mach and 3600 RPM? You will sacrifice takeoff
performances which is already not too good on canards.

I still like Vance's Idea. Profile will not be that bad as the top of
the cowl/ canopy can go straight back.

Paul Lamar

Paul, A caveat here as I have no time in type with a canard, but my high time friends tell me that more than one high speed taxi
has turned into an inadvertent first flight when  the throttle was closed and all that down force on the canard from the already
high thrust line was removed.

Rick

Sounds like a design defect to me. Lengthen the nose gear strut with a hydraulic
cylinder. Also increase the down thrust angle on the engine.


The tail on the prototype ME262 would not come up until the pilot hit the brakes
around 100 MPH. 

Paul Lamar
 
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