I'm building a Tiporare from an original W-K Hobbies fiberglass kit that I picked up on trade a few years back. This airplane will have a somewhat heavy YS .91 four stroke installed (inverted), so I'm tempted to build it as a tail dragger to avoid further weight up front. I'm also considering mounting the elevator and rudder servos in cutouts well back on the fuse to move additional weight rearward.

If built as a taildragger, how far forward of the CG should the axles be? I'm guestimating 3/8" to 1/2" ( I really want to keep the valve cover of that YS off the runway!). Any guidance is appreciated.

Regards,
Lee

One nice thing about the Tioprare is the amount of room in the fuselage to move stuff around to get the balance. My Tioprare has a painted fuse and MonoKoted tail and wing. With Tri gear retracts and a piped OS 61 pumper mounted on a flex mount the balance is right on with a 1600mah NiCd pack up front over the fuel tank. The OS61 pumper is pretty heavy and I expect that you should be able to do tri gear retracts with the YS and put the battery further back in the fuselage. There is also plenty of room to move the firewall back for the YS installation and easily have room for the nose gear. Don’t forget that removing the nose gear doesn’t help the balance very much when you have to move the weight of the main gear from behind the CG to way out in front of the CG.

Here’s a link to my Tiporare info that shows the layout http://www.rcuniverse.com/forum/m_2827386/tm.htm

Is W-K Hobbies, the hobby shop that was in a southern suburb of Dayton, OH, Miamisburg? I remember hanging out there in the late 70s and early 80s and seeing all the fiberglass molds. I think the owners name was Bill?

Yup, that's the hobby shop. Wasn't it Bill Elliot?

While I could get the plane balanced just by relocating the battery further aft, the goal is overall weight reduction. The mechanical mains and fixed tail gear should be considerably lighter than the pnuematics retracts, valve and air tank.

On another topic, do you have any tips on fitting the firewall? Do you use a profile gauge (like tile layers use) to draw out the pattern for the firewall or do you use some other method? Obviously the firewall is going to have to very accurately follow the contour of the fuse in order to make a really secure glue joint all-around. Having never built a kit such as this, I'm at something of a loss on how to proceed.

Thanks!

Lee, The Tiporare is not a good choice for a 4 stroke. I tried doing this for friend long ago..... make a long story short..... there is not enough room in the nose to put it inverted (can not even get a 60 size 2 stroke in the inverted or upright. It is that narrow). By the time I was done. I had to rework the nose which consists of widen it out, cut it in half, and making the bottom removable to get to the engine, etc..... I had more time in the front of the fuse then I did building the rest of the plane. Also....You will not have a choice in the matter as you will half to build a tail dragger out of it do to the firewall being so far back to get the 4 stroke in there. Not enough room for the nose gear.

Another thing to think about is the stab. The Tiporare has a anhedral(?spelling) stab. This will cause a problem with groung clearence if built as a tail dragger. You will half to build the stab staight. If you do not..... you will have very eventful landings (and takeoffs in some cases)

Don't get me wrong here... it can be done.... but the effort (amount of work) vs. final product (plane and flight performance) was not worth it in the end. When all was said and done, the plane didn't look like a Tiporare..... and didn't fly like a Tiporare.

Yes, I think that was his name. I spent a lot of time in that area, sometimes many weeks at a time. A bunch of us flew from our company parking lot over in Centerville that was a few miles from the Dayton Mall. W-K Hobbies was our supply depot. Bill was an upbeat, energetic guy and was always working on something new to sell.

It’s been a long time ago but as I recall the firewall in my Great Planes kit was pre-cut to size. I made a nose ring to space the back of the spinner out from the nose of the fuselage 1/16”. I ruff cut out the side of the fuse for the engine and then placed the engine in the fuselage, installed the spinner and prop and taped the spinner to the front of the fuselage. I used a Sullivan flex mount and I think I temporary installed the rubber insulators backwards so I had a flat surface on the back of the mount to determine the firewall position. I remember sanding the sides of the firewall so it would fit without distorting the glass fuselage sides. I don’t recall how I figured out where to drill the holes for the flex mount rubber insulators and blind nuts but it must have been fun!

I would normally never say this about an RC aircraft but with the Tiporare be careful not to build it too light. It has 720 sq in of wing area, is supper fast and needs a little weight to be stable. Mine came out at 7.78 lbs and feels very light in the air! That’s only a wing loading of 24.9 oz per square foot. With the piped OS 61 pumper it is ballistic.

PS. After looking at my plans I see that the firewall was pre-cut for an OS 61 installation which was the Tiporare power plant of the day.

OK, Well the tail dragger idea is out. The configuration with the anhedral stab would work (as I had planned it), but trying to visualize it, I have to agree with you that it just wouldn't look like a Tiporare.

However, I think I should have room to shoehorn the YS 4-stroke in the nose. It will be tight and is sure to elicit a stream of newly invented words at times, but I think it will fit.

There's a little downturn in the fuselage bottom near the rudder hingeline that will allow the fuse to scrape the ground without the stab touching. You could theoretically then build it in a taildragger configuration... although it wouldn't look right, it would be the only option if you wanted to do an inverted engine (with the exhaust running straight back).

I found an old W-K Hobbies business card. His name is Bill Keller and they were located at 19 N. Main, Centerville, OH.