I seem to remember seeing in an earlier post that the Primary Force tends to be tail heavy and benefits from using a little heavier engine. Any one try a Saito FA30S?

I believe the comments about the ARF Primary Force building tail heavy were relative to use of the FP25 that Mikey had on his original or an LA25.  Engines at about 8.5 oz seem to balance about right, although mine required the stock muffler on an OS 25FSR to balance properly.  Mine is, however, flown without the spinner.  It seems the design gods made the cargo area in my RX400h just long enough to fit the airplane without the spinner.  Wing T/E is against wheel wells and the rudder is almost touching the back of the seat.  With a spinner, the read door hits the spinner when it closes.
Steve

I am saving the Saito 40 for a little bigger plane so I figure the 30 could use a workout.

   Fellows, are you using the recommened c/g location ?  Ie 2" back from thre l/e at the fuse ??  My P force kit seems to be real nose heavy using an OS 32 SX with stock muffler, 1oz nose weight and an APC prop.
   It took all this to get the c/g where the plans called for it..
   Any suggestions will be appreciated...

The CG must be set at 2" back from the leading edge at the fuselage.  Pitch the stock muffler and use a tongue muffler this should bring the CG closer.  Further fine adjustments can be made to the CG by selecting different weight spinners, props, tailwheels, or Prather nose weights.

A mass produced model has to have an acceptable range of weight for the components.  Some might receive a stab that weighs slightly less or more that another.  This is the way it is.  To make a statement that they all come out tail heavy just isn't true because there are so many different engines available out there that it becomes almost imposable to have the perfect weight on all the components.

Later,
Mikey

Finished my new Primary Force. Brodak 25 9x5 prop 3 oz tank weighs 38 oz The only thing that worries me is I used a taller control horn and the swivel that you mount the push rod to
 on the bell crank seems to be in a slight bind because of the raised angle of the push rod.
Willis

I'm pretty impressed with the Primary Force.  I'm running a ball bearing OS 25F on pipe.  I didn't use the kit wheels or wheel pants cause I fly off grass and the balance is somewhere between 2-3" from the leading edge.  The engine weighs about 8oz, and I used a fairly heavy Great Planes aluminum spinner.  The weight of the header and pipe is pretty negligable.  Even with a CG further back then recommended it really flies well.  Using the same engine with pipe on several other planes resulted in the same tail heavy condition, so I can't blame the design or the kit.

I didn't use any of the kit hardware package.  I sleeved the pushrod with carbon fibre tube, and used a Rocket City 4-40 ball link.  The kit control horn was warped out of the box, so I substituted a Dubro horn.  The CA hinges didn't sit right with me, so I opened up the slots with a cutoff disk in the Dremel and used Dubro pinned hinges.  The supplied 4oz tank only holds about 3.75oz and is really too flexible to be anchored with rubber bands, but it fits and works just fine.  Out of the box or off the bench it flew very nicely.  It had a nasty warp in the wing that took some carefull bending and reshrinking the film with the heat gun, but all in all it's a nice product.  Much better then the TopFlite products.

HI Willis,

THe rule book allows .012 up to the .20, I know.......  I don't have the rule handy (changed last year??) to quote.  But, I *think* it goes up to .25 for .012.  As you know, though, it *might stretch* those .012s some!

Been flying my Primary Force short kit with an LA 25, stock muffler, aluminum spinner on 60 foot .012 cable lines.  Flies even better than when I had the Fox 35 Stunt with 60 foot .015 lines.  I watched Dan McEntee when he had his ARF PF out for the first time in St Louis.  He is running LA 25 I beleive, could be a Brodak 25.  I think both of us are using 10-4 props.  Have fun,  DOC Holliday

Bill
I know the feeling of stretchy lines I have a 72 oz ARF  Strega when I fly it with .018 lines. The handle feels like it has rubber bands for lines. I might try some solid lines or bring the Strega up to Huntersville and sell it. I just don’t like that big of a plane.
Willis 

I agree, Willis, I don't really care for a plane that size, either.  Aaron's Geo XL (Geo Bolt wing) at 62 oz. was plenty for me!

I Flew my Primary Force today. Brodak 25, 62 ft .012 lines 9x5 APC prop, 10% 22 1/2 &1/2., 4.85 sec. inverted 5.1 upright . wing slightly high up right, slightly down inverted. engine set at 10,700 fast but smoking pretty good. balance point 2 3/4 inches from leading edge. The plane is stable almost too stable I have installed a longer control horn didn’t need to do that.
After I got home I dropped the tank down a 1/8 inch, ironed out the warp and moved the push rod down two holes. I had a bind in the controls but after moving the push rod down two holes the bind is gone. I am going to cut two feet off the lines so I can slow the engines RPM  down . The plane fly as good as any thing that I’m flying. Sig has done a great job on this ARF, the coverings better by far then the other ARFs
Willis

Willis,
I mistakenly left the cotter pin fair lead off of the wire pushrod at mid-length and found my son's Primary Force had a distinct lag in elevator reaction. I have been using carbon fibre or fibreglass pushrods for so long I had forgotten the need for this. Just a reminder in case you haven't installed one.

Good luck with your Primary force, Michael's is the most fun I've had with a profile since, 5th grade!

Chris...