I've been out of the hobby for over 8 years and am building a Tiger 2 to get back into things. I was a competent builder and pilot previously, so I am not worrried about the flying or building again, but I would like to know if there are any issues to deal with on this kit before I build it. I plan to convert it to a tail dragger and to clip the wing 7" for a bit better roll rates and more spirited performance. Is the dihedral amount correct or does it need to be altered to eliminate roll coupling in knife edge? Any weak spots to reinforce? I plan on putting the gear in the wing and I will cut new ribs to accept the gear block and I will use some ply sub ribs to reinforce the block mounting. Also, I will be using two aileron servos instead of the one shown on the plans.

I searched this forum, but most of the posts were on the Tiger 60 and may not apply to the smaller size. Any thoughts/experiences welcome.

Thanks,
Mark

The September issue of Flying models has an article on modifying the Tiger 60 to make it a pattern practice airplane. All the changes look easy and reasonable. You can get a back issue.

Paul

http://www.flying-models.com/

mmattocks - Here's what I did when I built my Tiger2.

Mounted the engine sideways (OS FS70).
Cut off the front fuselage "cheeks" and installed a balsa engine cowl similar to my GP Ultra Sport 40.
Glued the fuel tank hatch to the fuselage for front-end strength.
Reinforced stabilizer and fin trailing edges with hardwood strips.
Made symmetric, open wing tips, braced top & bottom.
Added ½ inch to the rear of the rudder (helped with knife-edge flight)
Made it a tail dragger exactly the way you talked about with my main LG axles directly under the wing's LE
Fabricated & installed a tail-wheel setup similar to the one used on many Great Planes kits.
Countered the extra 4-stroke engine weight by placing the battery behind former “C�.
(Used a smaller battery pack to enable fitting it)
Knocked 1/2" (each side) off the recommended dihedral.
Replaced the aileron torque rods in the kit with 1/8-inch torque rods from the local hobby shop -
(Inserted them deeper into the ailerons and glued them in with epoxy)
Installed two aileron servos in the center of the wing

With the full wingspan and healthy aileron throws, my Tiger2 flies and rolls extremely fast. It's a rock-solid flyer and can handle a healthy wind.

== Mike ==

Thanks for the info, Mike. I forgot to mention that I am going to sideways mount the engine as well, as you describe and I will work up a cowl very similar to yours as well. I like the extra 1/2" on rudder, I will add that to my list. Also, will reduce the dihedral as you mention. I am thinking of shaped balsa for wing tips, similar to the way many pattern planes are done or open tips as you describe, I haven't decided yet. My aileron servos will be out in the wing panels, with short, straight linkages to the ailerons and I am going to use a dual pushrod DEPS type elevator pushrod setup with pull-pull on the rudder if it lines up OK.

What did you end up at for weight? Got any pics?


Mark

Hey Mark - My all up weight (no fuel) came out at just over 5 lbs 8 oz, which is lighter than I thought it would be. The OS 70 will pull it straight up out of sight. I rarely fly it at full throttle. I recently crashed it on landing due to radio problems and rebuillt the fuse forward of the wing with a more blunt cowl than my first one and I think it looks better. I've never posted pics, but I have a few if you'd like me to email them.

== Mike ==

Mike,

PM sent with my e-mail address.


Mark

Would anybody be willing to e-mail me a scanned copy of this article?
TIA.

Hi Guys,

I've built 2 Tiger 2's and here is what I have done so far. I ended up with an airplane that is still flying reliably after 3 years of continuous use.

1. That tail section is very weak in it's stock configuration, particularly the vertical fin attachment to the horizontal stabilizer, you may want to widen the horizontal stab center section by 10mm on each side, to give room for streamlined tri-stocks to attach on. The tri-stocks will strengthen the vertical fin attachment and will ensure that the vertical fin does not break easilly during handling and normal aerodynamic loads (i.e. while flying knife-edge). You would also need to widen the area on the vertical fin where the tri-stock will meet, to give the monokote some area to grab on to during covering. Attach the 3/4 x 3/4 inch tristocks on a location on the Vertical Fin where the "dorsal" butts-up with the fin leading edge. This will "lock" the vertical fin, horizontal fin and dorsal fin with maximum ridgidity.

2. Both vertical and horizontal stabs use 1/4x1/2 balsa sticks which have proven to flutter when performing high-speed/diving maneuvres, consider reinforcing them with 1/4" wide by 1/8" thick lite ply along the INSIDE perimeter of each panel (with the ply slightly soaked with thin CA to prevent delamination). This will give considerable strength with very little weight penalty.

3. Again, as reinforcement to the whole tailgroup, use basswood (or pine) tristocks to form a gusset between the ply stab platform underside and fuselage sides. Attach with EPOXY as you would do to the horizontal stab when attaching it to the stab platform. You'lle appreciate this modification once youve seen the whole tailgroup of a Tiger 2 come off during a high-speed dive!

4. WING - Those full-length 1/2 x 1/2 inch basswood spars are quite heavy and are not necessary on the outer halves of each wing panel. Consider using the basswood spars only on the center section of the wing, substitute 1/2 x 1/2 balsa sticks on the outboard side
of each wing banel. TAKE NOTE: You have to properly "spline" the balsa and the basswood spar so they attach solidly to each other.
Cut each part at an 8-degree angle so the glue-joint will be long enough to ensure that it is rigid. Position the joints such that they are covered by the shear webs for maximum strength. You'lle appreciate this mod in that it results to a better roll response.

5. WING JOINER- laminate some light ply to position itself between the upper and lower spars on the center section, this in turn will be "sandwiched" by the center spar joiners. The Tiger 2's wing center section is somewhat narrow and I did this mod so I could sleep better at night!

6. Landing Gear - whether you opt to have a tail dragger or tricycle gear layout, you will definitely have to strengthen the ribs where the gearblocks attach on to. I reinforced the stock rib with 1/8" thich ply (via tracing from the original rib) from the leading edge up to the part where the gear block attaches (the rest of the rib I left alone), and it also "locks" between the spars the same way the stock rib does. Those reinforcing plates that come with the kit are so badly cut that you would need to cut your own. I've seen stock Tiger2's "retract" their landing gear right throught the wing covering after a hard landing!

7. Ailerons - The ailerons have a notorious fluttering problem at high speed (when using the stock setup) and will definitely benefit from twin outboard aileron servos. I made my own aileron servo trays and located them at a rib bay that will position the aileron pushrods as closest to the aileron centers as possible (for maximum leverage and minimum aileron twist) I recommend robart 3/4" ball link control horns (the grey ones) for the ailerons and dubro swivel balls for the servo hook-up. This setup give minimum slop and a noticably better control response.

Depending on your style of flying, you would maybe want to modify the wingtips and wingspan as you discussed earlier. But the
Tiger 2 is such a sweet-handling airplane in it's original proportions (minus the weaknesses) that I didn't go that far. Reducing the dihedral does improve the tracking significantly (I also did the same!). You will end up with an airplane that tracks and behaves like a pattern plane yet lands so easy you'll forget you were flying a low winger to begin with! Good Luck!