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Building Tips and technical articles. => Building techniques => Topic started by: Douglas Ames on September 18, 2011, 07:38:43 PM

Title: A Question for PAT JOHNSTON - Brodak Corsair
Post by: Douglas Ames on September 18, 2011, 07:38:43 PM
I noticed on the prototype full fuse. Corsair plans the engine crutch is offset with an optional hinged rudder.
On the Brodak plans the crutch is straight 0/0.

Was this the result of your finds when trimming the prototype?
Did you find it necessary to cock the rudder any?

I'm installing a Saito .40 and have built the crutch 0/0, the fin/rudder was assembled faired but I can attach it at an angle if needed.

Thanx, Doug
Title: Re: A Question for PAT JOHNSTON - Brodak Corsair
Post by: Pat Johnston on September 19, 2011, 11:24:50 AM
Doug,
The original Corsair (profile) flew with no offset and had an adjustable rudder which was offset possibly 3/8".  Flew well that way.  These days, I prefer just a little engine offset so that is why there was 2 degrees shown on my original plans.  Brodak may have set the engine with no offset.  I suspect that a zero degree offset on the engine thrust would still be good and line sweep and rudder will get things well adjusted.
I would recommend making the rudder hinged with an adjustable linkage so it can be altered to find the happiest setting. 
Pat Johnston
Skunk Works.
Title: Re: A Question for PAT JOHNSTON - Brodak Corsair
Post by: Douglas Ames on September 19, 2011, 04:46:28 PM
OK thanks!

There is NO offset shown on the Brodak plans, and the instructions tell you to glue the fin/rudder together and install straight.

My crutch is already epoxied "in stone" 0/0, but I will cock the fin/rudder a little for P-factor and line tension.

Thanx, Doug
Title: Re: A Question for PAT JOHNSTON - Brodak Corsair
Post by: wwwarbird on September 20, 2011, 10:12:17 PM
 I'd mount the engine O/O and like Pat suggests, make the rudder adjustable. Good plan for most any good sized Stunter.

 I have serious doubts about the Saito .40 being enough power for the design though, in fact I'll say it's not. I'd strongly suggest the .56 or .62. y1
Title: Re: A Question for PAT JOHNSTON - Brodak Corsair
Post by: Rick Henry on October 04, 2011, 10:07:30 AM
Hey Doug, How is the Corsair coming along?  Any Pics?  I am going to start mine soon but I have to buy a Brodak wing jig first and finish up a couple home repair projects before winter.  

Keep us posted.

Rick Henry