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Feb 04, 2014, 11:27 AM
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Big Red

Several years ago, a guy came to the field selling surplus stuff and I bought ($5) a set of balsa covered foam cored wings NIB. They evidently had been bought from a wing maker to rebuild a model that never got rebuilt.

The panels were forty inches. I determined to use them to construct a self design. My favorite era is thirties through the WW-II era so a thirties looking open cockpit sport plane was envisioned, sketched, drawn and scratch built.

Construction and Flight
  • Conception - spring of 2011
  • Drawing - summer of 2011
  • Acquring wood and hardware and final drawings - late summer and fall 2011
  • Buiding - January - April 2012
  • Maiden - early May 2012
  • Flown - often for fifteen months until mishap during summer 2013
Wingspan 96"
Power 35cc gas
Weight 16.75 lbs.

Video of maiden
Sport35.mpg (8 min 5 sec)

Build log

The Crash

Normally, flaps were used for landing and a fast idle was mixed with the flaps which worked very well with any headwind but lacking a headwind, I'd suffered a lengthy landing and determined to go back up and do better and chose to land without the flaps/fast idle. There was a cross wind in my face that I failed asses as a danger and slowed too much on base leg and stalled when turning onto final. The plane is salvageable and needs the front section, wing tips and rudder repaired.
Last edited by AA5BY; Feb 04, 2014 at 11:41 AM.
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Feb 05, 2014, 12:22 AM
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looks and sounds awesome.
Feb 05, 2014, 09:49 AM
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It was a fun project. It flew well and I thought looked good. I'll be happy to have it flight worthy again.
Feb 05, 2014, 09:28 PM
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half the fun is the fixing of things
Feb 05, 2014, 09:45 PM
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Yeah.... I usually enjoy doing repairs, all though I did a major rebuild of a Taylor Craft twice and hope if it crashes again it will be totaled. It is still air worthy and gets flown occasionally.
Aug 02, 2014, 08:48 AM
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Repairs Underway

Having somewhat caught up on my list of home repairs/additions, Big Red was put on the bench and repairs have begun.

The greatest damage consisted of a total wipe out of the fore section ahead of F2. The lower one quarter of the rudder had damage, both wing tips (one of them wiped out), one wing root rib torn out, and a longeron brace broken loose.

The rudder hinge pins were removed and the breaks simply pushed back together and glued and it is ready for recovering.

The longeron brace was simply glued back in place.

The wing root rib was simply inserted back into its location and glued.

One wing tip simply required gluing parts back together.

The other wing tip will need rebuilt.

The big damage area was the fore section with all ahead of F-2 needing new structure. Using the multi tool, everything left ahead ahead of F-2 was sawed away. Then the plane was taken to the bench belt sander and sanded until F-2 was gone to prepare to accept a new fore section from F-2 forward.

Provided is one pic of that progress with a partially built new fore section held temporarily in place with large rubber bands.
Aug 02, 2014, 09:08 AM
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Bolt On Stabs

One point worthy of making is the great advantage of bolt on stabs. The plane is five feet long and it is far easier to manage with the stabs removed.

If designing a large plane, I greatly recommend that stabs be bolted on or on tubes. Though I like tubes, I like bolt on stabs even more as they allow removal of both the vertical and horizontal.
Aug 19, 2014, 09:19 PM
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An interesting Discovery During Repairs

After the rebuild of the fore section, it became time to provide new linkage to the throttle and choke. In prep of firing up the receiver that had remained in the plane during the year it hung broken, I charged the two LiFe flight batteries to discover that after sitting for a year following the crash near the end of the second flight that day, they both during a balance charge required identical milliamps to recharge. Interesting but not the most interesting discovery.

After the receiver fired up with lights coming on within both the receiver and satellite, I hit the gear switch that I've used for the choke and magneto on switch for a couple of other models, thinking the choke was on the gear channel. The choke servo didn't move... but something was. Not noticed at first, the elevator servos were moving in response to the gear switch. What was that all about? As previously noted, the stabs were off the plane during repairs and the servo rods were simply bound beside the tailpost with masking tape.

In pos 0, the elevators (if they were in place) would have gone hard over in opposite directions. In pos 1, they centered (albeit I don't know if they would have been in trim) and in pos 2, they again went hard over in opposite directions and reversed from pos 0. I quickly began to think that the cause of the crash had been discovered and it wasn't pilot error as I'd accepted.

I next noted that the choke was on the aux 3 right side slider channel but why was the gear switch effecting the elevators. Obviously in either pos0 or 2, it would have meant almost instant crash and without mounting the stabs, I didn't know if pos 1 was in trim.

It was noted that in the wing setup the gear ch was mated to the elevator for dual servo elevators, which is fine and actually outlined in the manual. But, when doing so, the gear ch is supposed to be taken away from the gear switch and the gear switch should certainly have no effect upon the primary elevator ch. There were no mixes involving the gear channel or assignment of the gear switch to anything.

Perplexed, the gear ch was un-mated from the elevator and when doing so, the left elevator reacted properly to the gear switch without affecting the right elevator. And of course, there was no slaving of the left elevator with no mating set. Going back to the wing setup, the gear ch was re-mated just as it had been, and lo.... the gear switch then had no affect upon the two elevators and they seemed to work nominally.

Accordingly, my conclusion is that transmitter computer logic glitched and somehow linked the gear switch to the elevators and did so while in flight and it caused the elevators to go hard over in opposite direction throwing the airplane into a roll without adequate elevator response. I recall the plane suddenly rolling and correcting with some amount of aileron but then suffering an uncontrollable loss of altitude and finally holding the wings as level as possible and cutting the power and letting it come down where it cartwheeled, smashing the nose section, bending the wing tube and breaking the wing tips and rudder.
Sep 29, 2014, 08:07 AM
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Repairs are complete and Big Red is flying again

My final conclusion was that my transmitter suffered a single even upset that caused the crash. That is where a cosmic radiation particle collides with a microprocessor or memory chips and slips a bit with a resulting software error. The error that caused the crash stayed in memory and manifested the crash producing symptoms until cleared.

I've since upgraded the firmware in the transmitter and changed the elevator slave channel to another axillary channel in hopes it doesn't repeat.

At any rate, Big Red is airworthy again and I've flown it many times in the past few weeks.

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