Mi. ( Yooper)
Hello everyone,
I have finally commenced flight testing on my newly assembled Smith aviation/ Backcountry Super Cub and I have a problem with attaining neutral trim. let me intoduce my senario, first I will layout all the equipment and configurations, so maybe someone will have an idea of what is going on? here is the aircraft and how it is equiped.
1. 2005 year model Serial number 079 Nick Smith Aviation PA-18 4" wide body Super cub L-21 fuselage
2. Wings, by Smith/Axlesen with 24 gal mains and 10 gal aux, extended flaps, Ailerons and squared
3. Mackey leading Edge Slats
4. Univar struts
5. STOL SPEED Micro VG's placed 3/4 inch behind trailing edge of slats on Wings and Under Horizontal Stab spaced according to there instructions
6. wing tips are the droop tips provided by smith aviation
7. Mackey SQ2 engine mount with 0 thrust line and cowling
8. Aero Sport 0320 B2B, 8.5 to 1 compression with Bart's Mods for supposedly 170+ HP
9. Prop is Catto 84X37 New, designed for this configuration and primarily for climb obviously
10. Duel P-Mags
11. Earth X Batttery
12. light weight starter and alternater
13. Vettermens duel Exhaust with heat muffs
15. the Landing gear is 3" extended with 31" bush wheels, Grove double puck brakes, matco master cylinders
12. floor boards are 3003 .045 diamond decking all the way to back of extended baggage
13. interior is 6061T6 .020 covered with 3M Carbon Wrap
14. Seats are Orgon Aero front and full width back with under seat storage box
15. ABW/Scott 3200 Tail Wheel
16. Rudder and Elevator Gap Seals
17. Panel has Dynon D180, Garmin GTX327, MGL V-10, Uma Airspeed indicator
Weight and Balance comes out at, Right Main 583 pounds, Left Main 591 pounds, Tail Wheel 84 pounds, 6 qrts oil in engine, no fuel, total 1258 pounds Emty using digital Scales with plane in level flight position, reading plumb at firewall and with leading edge of wing at 1.5 inches ahead center of axel.
With me in the front seat at 235 pounds at level cruise speed (which is slow by the way) Im seeing about 75 MPH at 2250 RPM I can not get a nutural stick with full nose up Trim, even at full throttle I still can not get a neutral stick, it is very close but wont get it, I added 80 pounds to the back seat for a flight test and I am now able to get nuteral stick but with not much nose up trim left to spare on the horizontal Stabilizer.
We double checked all the Stab Readings with the plane leveled and come up with 3 degrees down leading edge of stab(Nose Up Trim) and very close to 4 degrees up leading edge(Nose Down Trim) from looking at the TCDS's we appear to be with in range of what is required, at least it appears that way unless i'm reading it backwords, our only other thought was that maybe the rear Stab Tower might be welded on to low,(this was a problem with some earlier Smith Cubs) but it cant be if we are getting the required readings on the Horiz Stabilizer, we also checked the wings for wash, dihedral, and AOI all appear to be within the correct limits with the AOI at 1.7 degrees, dihedral at 3 1/8 inches and the wash at 1.8 degrees from wing root rib to tip rib.
just one other thing I forgot to mentioned, we have not yet installed the flap gap fairings, and we do experiance some shake on tail with full flaps deployed, we will install these as soon as I can find a source for them, anyone? I dont think this would have an effect on our trim issue, correct me if i am wrong.
What can we Do to correct this problem without having to add weight in the tail? or is this my only option? Ideas and/or opinions are much appreciated!
Rick
I have finally commenced flight testing on my newly assembled Smith aviation/ Backcountry Super Cub and I have a problem with attaining neutral trim. let me intoduce my senario, first I will layout all the equipment and configurations, so maybe someone will have an idea of what is going on? here is the aircraft and how it is equiped.
1. 2005 year model Serial number 079 Nick Smith Aviation PA-18 4" wide body Super cub L-21 fuselage
2. Wings, by Smith/Axlesen with 24 gal mains and 10 gal aux, extended flaps, Ailerons and squared
3. Mackey leading Edge Slats
4. Univar struts
5. STOL SPEED Micro VG's placed 3/4 inch behind trailing edge of slats on Wings and Under Horizontal Stab spaced according to there instructions
6. wing tips are the droop tips provided by smith aviation
7. Mackey SQ2 engine mount with 0 thrust line and cowling
8. Aero Sport 0320 B2B, 8.5 to 1 compression with Bart's Mods for supposedly 170+ HP
9. Prop is Catto 84X37 New, designed for this configuration and primarily for climb obviously
10. Duel P-Mags
11. Earth X Batttery
12. light weight starter and alternater
13. Vettermens duel Exhaust with heat muffs
15. the Landing gear is 3" extended with 31" bush wheels, Grove double puck brakes, matco master cylinders
12. floor boards are 3003 .045 diamond decking all the way to back of extended baggage
13. interior is 6061T6 .020 covered with 3M Carbon Wrap
14. Seats are Orgon Aero front and full width back with under seat storage box
15. ABW/Scott 3200 Tail Wheel
16. Rudder and Elevator Gap Seals
17. Panel has Dynon D180, Garmin GTX327, MGL V-10, Uma Airspeed indicator
Weight and Balance comes out at, Right Main 583 pounds, Left Main 591 pounds, Tail Wheel 84 pounds, 6 qrts oil in engine, no fuel, total 1258 pounds Emty using digital Scales with plane in level flight position, reading plumb at firewall and with leading edge of wing at 1.5 inches ahead center of axel.
With me in the front seat at 235 pounds at level cruise speed (which is slow by the way) Im seeing about 75 MPH at 2250 RPM I can not get a nutural stick with full nose up Trim, even at full throttle I still can not get a neutral stick, it is very close but wont get it, I added 80 pounds to the back seat for a flight test and I am now able to get nuteral stick but with not much nose up trim left to spare on the horizontal Stabilizer.
We double checked all the Stab Readings with the plane leveled and come up with 3 degrees down leading edge of stab(Nose Up Trim) and very close to 4 degrees up leading edge(Nose Down Trim) from looking at the TCDS's we appear to be with in range of what is required, at least it appears that way unless i'm reading it backwords, our only other thought was that maybe the rear Stab Tower might be welded on to low,(this was a problem with some earlier Smith Cubs) but it cant be if we are getting the required readings on the Horiz Stabilizer, we also checked the wings for wash, dihedral, and AOI all appear to be within the correct limits with the AOI at 1.7 degrees, dihedral at 3 1/8 inches and the wash at 1.8 degrees from wing root rib to tip rib.
just one other thing I forgot to mentioned, we have not yet installed the flap gap fairings, and we do experiance some shake on tail with full flaps deployed, we will install these as soon as I can find a source for them, anyone? I dont think this would have an effect on our trim issue, correct me if i am wrong.
What can we Do to correct this problem without having to add weight in the tail? or is this my only option? Ideas and/or opinions are much appreciated!
Rick