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- Jan 12, 2017
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The Hevle brothers' Classic is a one-off, wood and fabric, tandem Fly Baby powered by a Rotec R2800 built in California. Ron Wanttaja reviewed it in Kitplanes 2004/5 (expanded version of the article here: Hevle Classic Pilot Report). It was eventually acquired by Paul Chertikeeff, who had it shipped to Australia, where it is currently serving as a Rotec demonstrator.
The Hevles used a truss layout developed (for his own use and shared online) by aerospace engineer David Munday. CAD Drawings
(RW's comparison of the two shown below.)
Basically, the Fly Baby fuselage is lengthened about 1', the wing is pulled back a similar amount, so that the passenger in front is now close to the aircraft's CG and the pilot in the rear pit counterbalances the heavier engine (for Munday an 0-290; for the Hevle's a Rotec 2800). Hevle wingplan is stock, but spars are thickened from 3/4" to 1" (as Munday recommended). (Munday also recommended some thickening of the fuselage structural members. Don't know if Hevles incorporated this.) Vertical fin and rudder are stock (I think). The span of the horizontal stab is increased by 2'. Bracing wires upgraded. One issue with this design is the fact that passenger is now further from the tailpost and thus, potentially, more at risk in the event of a nose-over. (Munday mentioned the roll-over risk and worked on ways to incorporate a rollbar.)
My thoughts:
How about planning a two seat Fly Baby powered by an R2800 but (to simplify things) going in a different direction with the fuselage (circling back to some ideas I've floated on HBA).
Suppose we are willing to have the passenger face backwards (like the mannequins in the Boche Baby pseudo-Junkers CL.1, but human). In my mind the passenger would be a grandchild or other (not necessarily small) joyrider, rather than a trainee who needs to face forward and have dual controls. Presumably the fuselage still needs to be lengthened to provide sufficient tail authority for the greater weight and power, but leave the wing where it is in Bowers' original and pull the cockpit back a bit such that with pilot and passenger (whose CGs, sitting back to back, are now much closer together) and a Rotec in front, the aircraft's CG remains as it was, and for flight without a passenger, some ballast is set in the tail. I am obviously no engineer, but intuitively it seems to me that this affords a more closely-coupled aircraft and also allows the tailpost to provide a bit more protection for both pilot and passenger.
Thoughts?
The Hevles used a truss layout developed (for his own use and shared online) by aerospace engineer David Munday. CAD Drawings
(RW's comparison of the two shown below.)
Basically, the Fly Baby fuselage is lengthened about 1', the wing is pulled back a similar amount, so that the passenger in front is now close to the aircraft's CG and the pilot in the rear pit counterbalances the heavier engine (for Munday an 0-290; for the Hevle's a Rotec 2800). Hevle wingplan is stock, but spars are thickened from 3/4" to 1" (as Munday recommended). (Munday also recommended some thickening of the fuselage structural members. Don't know if Hevles incorporated this.) Vertical fin and rudder are stock (I think). The span of the horizontal stab is increased by 2'. Bracing wires upgraded. One issue with this design is the fact that passenger is now further from the tailpost and thus, potentially, more at risk in the event of a nose-over. (Munday mentioned the roll-over risk and worked on ways to incorporate a rollbar.)
My thoughts:
How about planning a two seat Fly Baby powered by an R2800 but (to simplify things) going in a different direction with the fuselage (circling back to some ideas I've floated on HBA).
Suppose we are willing to have the passenger face backwards (like the mannequins in the Boche Baby pseudo-Junkers CL.1, but human). In my mind the passenger would be a grandchild or other (not necessarily small) joyrider, rather than a trainee who needs to face forward and have dual controls. Presumably the fuselage still needs to be lengthened to provide sufficient tail authority for the greater weight and power, but leave the wing where it is in Bowers' original and pull the cockpit back a bit such that with pilot and passenger (whose CGs, sitting back to back, are now much closer together) and a Rotec in front, the aircraft's CG remains as it was, and for flight without a passenger, some ballast is set in the tail. I am obviously no engineer, but intuitively it seems to me that this affords a more closely-coupled aircraft and also allows the tailpost to provide a bit more protection for both pilot and passenger.
Thoughts?
