Cardinal Nose

Hi Gang!
Some more questions on the on-going Cardinal construction. I've mounted the engine, a Lew Woolard Silver Foxx 40. I've noticed that the cut out for the engine extends back more than an inch from the rear of the engine, when I mount it so that the nose ring if flush with the front of the fuse. This is consistent with the location in the plans, but given the large hollow spot behind the engine I am concerned about a couple of things. 1) That I will get as Mike Pratt calls it the "tuning fork effect", which may contribute to vibration and 2) a nose heavy ship since the foxx 40 isnt exactly lightweight.
My question is should I trim the front of the nose and shift the engine back to avoid the above problems or should I not worry and just "build it to the plans"?
Thanks,
Brian

Yes it is better if it is back in the cut out as far as possible.
If the airplane is painted, temporally mount the tank, wheels etc and position the engine where the cg is right. If it is unfinished figure about 75% of the paint is going to be behind the cg and do a best guess.

The Fox is both heavy and short shafted. Another solution is to use a prop extension to keep the original moments close. Both 1/2" and 3/4" units are available from Fox and other suppliers. A down side is that props must be reamed to 5/16 to use the extensions which makes balancing more difficult.

I am running a Silver Foxx 40 BB with 3/4 shaft extension and am becoming more and more impressed with it. Powerful, fairly economical for it's power and displacement but needs 1 to 2 hours on it before it really comes into its own. Also needs a snoot full of fuel to cold start. Starting should be no problem on a profile and it should make a great combo with the Cardinal. A 4.5 oz tank should be more than enough. A really compact little tongue muffler is also available-Leonard may be able to furnish one.

My Cardinal/ST.46 needs a quarter ounce of tail-weight even after three coats of Rustoleum paint on most of it. (Hit a post, rebuilt the wreck, screwed up the second paint job & had to do it again. Duh.) I don't know how the weight of the ST compares to the weight of the Fox, (someone here will know) but if it is comparable you could probably lop some off the nose & get rid of some weight on both ends. I have a coat of light fiberglass around the wing/fuse joint going out onto the nose a ways now, but I didn't have any vibration problems before either with the open part behind the engine .
Nils

>...I don't know
>how the weight of the
>ST compares to the weight
>of the Fox, (someone here
>will know) but if it
>is comparable you could probably
>lop some off the nose
>& get rid of some
>weight on both ends....
>Nils

with a tongue muffler, the Fox 40 will weigh in at about 9 1/2 ounces--a bit less than the ST. Ironically, the way Fox makes those engines, the plain bearing version weighs more than the ball bearing version, and the iron piston version weighs less than the ABC (brass liners are heavy). The lightest one, however, is the older version with only one ball bearing on the back of the shaft. That one, with the iron piston, is my favorite (got a couple).

Leonard Neumann