Title: Pitot heat
The aircraft pitot tube runs from the nose, along the left wall, via an aluminum hard tube. I installed a 12 volt, 12 watt resistive heating tape, contacting the face of the tube as far forward as possible within the nose compartment. In addition to heat conducting adhesive, the tape is secured with 3 safety wire wraps and does not touch the fiberglass structure. The location is not subject to motion and this is fully adequate for securing the heat tape. Since the aircraft is _not_ intended for flight in known icing conditions, a short term test was useful information. I used a digital kitchen temperature probe of known accuracy. First, I tested the temperature of the tape itself. Under 13.5 volts it heated to 180 degrees, with probe in direct contact with the heat tape. Second, I secured the tape as described above - the tape was tied to the aluminum pitot tube and did not touch the epoxy structure. The temperature probe was placed inside the pitot, touching the side wall at a contact point with the heat tape. At 13.5 volts the tape heated the mouth of the pitot, first from 85F garage temp to 127 (3 minutes), then climbed slowly to 141F over 15 minutes. The adjacent composite surface heated to only 115F. I was surprised the glass temp did not go higher and repeated the measurement with the same result. The heat tape came with 24 AWG leads, which were secured with D-sub pins to 22 AWG shielded twisted pair wire. Each pin connection is secured with shrink tubing and the pair covered in a larger piece of shrink tubing. The draw is 1 amp. Pitot heat is switched at the panel and separately fused at 3 amps, giving the wire significant protection. I again used DB pins for the connections. DB pins are rated for 5 amps in low density loads. This load is significantly less than the rating of the DB pin connection. Because the heat tape is an untested building practice, I will test again when measuring temperature and amperage draw of the completed airplane.


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