Hello all, <?:namespace prefix = o ns = "urn:schemas-microsoft-com
fficeffice" />
I have been working on an AcroSport II I bought from a local builder late in 2009. I flew it only a few hoursshortly after purchase and not without incident. I spent most of 2010 working on it and thusly did not fly it until late October 2010, and then only a few hours and only with an instructor in the front seat.
During last year I have been working on many different improvements and while doing so Ihave observed several things about the landing gear andwings and theirassembly to the fuselage that are inconsistent.
[To eliminate confusion, I will reference componentlocations as "pilot side" and "passenger side"of the airframe as if it were a side-by-side aircraft although it is not. Also, I use the bolt that protrudes downward through the rear tire leaf springas the center reference point in determining the symmetry of the gear, wings, etc. on the airframe from the pilots side as compared to the passenger side.]
We, the instructor and I,noticed several flight characteristics that are not only strange but also dangerous. Most noticeable was the difficulty in keeping the aircraft headed straight down the runway when taking off and landing (aleft turningtendencywas more than apparent on each high speed use of the runway).Here are thediscrepanciesI found:
1) the passenger side main gear tire had a toe-in of 3.5 degrees, (the pilot side tire was straight in line with the airframe and square in alignment to the imaginary plane established across the front face of the main gear tiretread),
2) the wing tips of the lower wings were not at the same elevation relative to the hangar floor (almost 2" difference in height even though the airframe is level in all directions),
3) the dihedral was different on each wing and neitherwere at the required +2 degrees,
4) the flying wires and landing wires were not very tight, and in fact one of the front flying wires on the passenger side "fluttered(?)" when flying (there is onewooden spreader bar attaching each set oflanding and flying wires together on each side),
5) the center wing section is offset to the passengers side by 7/16" from being centered over the fuselage, (consequently the roll wires are not evenly inserted into the barrels of the clevis' attachment fittings, nor is the front pair of flying wires on the passenger side long enough to provide adequate threads for double nut applicationat the upper wing connection points), (also a result of the rearward 'twist' in the upper passenger side wing section)
6) placing a string line across the entire upper wing from side to side, it is obvious that the wings are not level as the gap distance between the string and the upper surface of the wing is not uniform across the entire top of the three wing sections,
7) The distance between the upper wing rear sparlandingwire attachment brackets is 1 1/4" TIR (5/8" rotation required in the center wing section to reset thecenter wing section perpendicularity to the longitudinal centerline of the fuselage),
8) the distance from the leading edge of the upper wing rearward to the leading edge of the lower wing differs by 2" (as measured atthe passenger side"I" strut outboard location compared to the pilots side"I" strut outboard location). Note: The lower wings are perpendicular to the fuselage centerline within 1/8" as measured at the rearmost point of the outboard opening in the lower aileron clearance well.
9) As a consequence of items 7 & 8, the set of landing wires and rear flying wires on the passenger side interfere with each other. If they were to betensioned to the proper specifications the edges of the wireswill distort the straightness of each contacting wire and the stress pointcreated at thiscontact junction willcreate a potentially dangerous condition. In addition, I do not have faith that the wooden spreader bar and cable tie attachment method of the stainless steel wiresto it is robust enough to maintain separation of the tensioned wires throughout an amateur pilots aerobatic maneuvers.
I havethe original set of plans for this airframe build project, so, I am interested in any advice anyone with experience may have with the following questions;
A) What is the effect of not having the center wing section and right / left wings centered on the airframe?Is it necessary to reset them to factory specs understandingthe likelihood of needing to re drill mounting holes in spars / brackets and rebuilding the "I" struts as required to maintain perpendicularity, symmetry, and proper parallel spacing between upper and lower wing sections?
B) What is the desired distance the leading edge of the upper wing should be from the leading edge of the lower wing? (I believe this is called the "stagger" of the wings). I cannot determinethis information from my set of design plans.
D) Since the upper wings are already bolted into place with the errors seemingly built in, how would you recommend to reestablishthe mounting ofthe spars? Wouldn't re drillingof theattachment holes elongate the reamed hole and allow for some potential lack of future stability in the attachment? Could a larger hole be drilled and larger bolt be installed to establish a new centerline of the mounting attachment location without compromising the amount of remaining material in the steel bracket and weakening the strength and integrity of the steel bracket / upper wing mounting point? If so, what would the maximum diameter of hole / bolt be?
E) What is the effect of the wire interference discussed above? (I believe the interference in the passenger side landing / flying wires would be eliminated if the passenger side upper wing is reset to the proper location.)
I know this is a lengthly description and request for help, but without knowing all of the issues together, the interaction effects might be missed and the entire corrective action process compromised.
I appreciate those experts within the forum that can offer constructive comments on these questions. Any help you can provide is greatly appreciated.
Thanks,
fficeffice" />I have been working on an AcroSport II I bought from a local builder late in 2009. I flew it only a few hoursshortly after purchase and not without incident. I spent most of 2010 working on it and thusly did not fly it until late October 2010, and then only a few hours and only with an instructor in the front seat.
During last year I have been working on many different improvements and while doing so Ihave observed several things about the landing gear andwings and theirassembly to the fuselage that are inconsistent.
[To eliminate confusion, I will reference componentlocations as "pilot side" and "passenger side"of the airframe as if it were a side-by-side aircraft although it is not. Also, I use the bolt that protrudes downward through the rear tire leaf springas the center reference point in determining the symmetry of the gear, wings, etc. on the airframe from the pilots side as compared to the passenger side.]
We, the instructor and I,noticed several flight characteristics that are not only strange but also dangerous. Most noticeable was the difficulty in keeping the aircraft headed straight down the runway when taking off and landing (aleft turningtendencywas more than apparent on each high speed use of the runway).Here are thediscrepanciesI found:
1) the passenger side main gear tire had a toe-in of 3.5 degrees, (the pilot side tire was straight in line with the airframe and square in alignment to the imaginary plane established across the front face of the main gear tiretread),
2) the wing tips of the lower wings were not at the same elevation relative to the hangar floor (almost 2" difference in height even though the airframe is level in all directions),
3) the dihedral was different on each wing and neitherwere at the required +2 degrees,
4) the flying wires and landing wires were not very tight, and in fact one of the front flying wires on the passenger side "fluttered(?)" when flying (there is onewooden spreader bar attaching each set oflanding and flying wires together on each side),
5) the center wing section is offset to the passengers side by 7/16" from being centered over the fuselage, (consequently the roll wires are not evenly inserted into the barrels of the clevis' attachment fittings, nor is the front pair of flying wires on the passenger side long enough to provide adequate threads for double nut applicationat the upper wing connection points), (also a result of the rearward 'twist' in the upper passenger side wing section)
6) placing a string line across the entire upper wing from side to side, it is obvious that the wings are not level as the gap distance between the string and the upper surface of the wing is not uniform across the entire top of the three wing sections,
7) The distance between the upper wing rear sparlandingwire attachment brackets is 1 1/4" TIR (5/8" rotation required in the center wing section to reset thecenter wing section perpendicularity to the longitudinal centerline of the fuselage),
8) the distance from the leading edge of the upper wing rearward to the leading edge of the lower wing differs by 2" (as measured atthe passenger side"I" strut outboard location compared to the pilots side"I" strut outboard location). Note: The lower wings are perpendicular to the fuselage centerline within 1/8" as measured at the rearmost point of the outboard opening in the lower aileron clearance well.
9) As a consequence of items 7 & 8, the set of landing wires and rear flying wires on the passenger side interfere with each other. If they were to betensioned to the proper specifications the edges of the wireswill distort the straightness of each contacting wire and the stress pointcreated at thiscontact junction willcreate a potentially dangerous condition. In addition, I do not have faith that the wooden spreader bar and cable tie attachment method of the stainless steel wiresto it is robust enough to maintain separation of the tensioned wires throughout an amateur pilots aerobatic maneuvers.
I havethe original set of plans for this airframe build project, so, I am interested in any advice anyone with experience may have with the following questions;
A) What is the effect of not having the center wing section and right / left wings centered on the airframe?Is it necessary to reset them to factory specs understandingthe likelihood of needing to re drill mounting holes in spars / brackets and rebuilding the "I" struts as required to maintain perpendicularity, symmetry, and proper parallel spacing between upper and lower wing sections?
B) What is the desired distance the leading edge of the upper wing should be from the leading edge of the lower wing? (I believe this is called the "stagger" of the wings). I cannot determinethis information from my set of design plans.
D) Since the upper wings are already bolted into place with the errors seemingly built in, how would you recommend to reestablishthe mounting ofthe spars? Wouldn't re drillingof theattachment holes elongate the reamed hole and allow for some potential lack of future stability in the attachment? Could a larger hole be drilled and larger bolt be installed to establish a new centerline of the mounting attachment location without compromising the amount of remaining material in the steel bracket and weakening the strength and integrity of the steel bracket / upper wing mounting point? If so, what would the maximum diameter of hole / bolt be?
E) What is the effect of the wire interference discussed above? (I believe the interference in the passenger side landing / flying wires would be eliminated if the passenger side upper wing is reset to the proper location.)
I know this is a lengthly description and request for help, but without knowing all of the issues together, the interaction effects might be missed and the entire corrective action process compromised.
I appreciate those experts within the forum that can offer constructive comments on these questions. Any help you can provide is greatly appreciated.
Thanks,
