Compass what is that?
bsacks05 said:
Anyone have a good supplier for a magnetic compass? Bruce Sacks RV9 N659DB Flying by Summer?!
You can get a common "ubiquitous" WWII airpath compass used on eBay for 15-35 bucks tops. Even new they are just a bit over 100 clams.
http://www.aircraftspruce.com/catalog/inpages/airpath_compass1.php
My dad called them a "jelly jar" compass. When I was CFI'ing full time years ago I enjoyed teaching compass turns, which is really totally useless but fun, which leads me to my point;
A wet compass is totally useless (yes I said it). What do I mean? I mean with GPS I fly track. I never look at the compass any more. If I filed IFR with my RV-7, I would need (compass) heading to fly a vector. In the Boeing I fly at work, there is a compass but really never looked at. On the B737 it folds out of view, where it stays most of the time. You tell me next time you go fly, how much you really use a compass to fly VFR.
Part two of why I never use my compass, I have a Dynon EFIS-10 with magnetic heading derived from a remote electronic ("field sensor"). Much more stable than a jelly jar, and the corrections are electronically "swung" into the display. No more compass correction. I see no reason to back the Dynon mag hdg with a 65 year old compass.
Last point,
we are experimental and no compass is needed at all per the FAR's (at least day VFR)! Debate this all you want, but call the FAA 1st. I know that sounds controversial; I did not believe it until I called my local FSDO. I was shocked, Yep no compass, airspeed, altimeter or engine instruments needed (see below). Would I fly with out airspeed and altimeter? (No) How about RPM, MAP, Oil P, Oil T? (No) Well regs and common sense are two different things. I don't think 3 miles visability is VFR or 30 min of reserve fuel is enough for VFR. I AM NOT suggesting or recommending, just pointing out the actual requirements for discussion.
So as a light cheap alternative consider one of the many electronic compass for cars. Some come with altimeter and dual in/outside air temp.
http://www.thecompassstore.com/auto.html.
The last option is no compass at all for day VFR. Which I support below.
Cheers George ATP/CFI
** Per part 23 one mag compass must be NOT electrically powered; Experimental's do NOT need to adhere to part 23 (that's without debate).
In part 91 for day VFR equip it says we need a compass but no mention of electrical power, so a Dynon or any EFIS or car electronic compass is good. Some DAR's feel you need to have a "Jelly Jar" compass, which is not correct. (Mel correct me if I am wrong our you disagree.)
In fact as an experimental we don't need to meet any regulation unless its noted in the operation limitation. Some feel we don't need any instruments at ALL for day VFR. There are usually only notes for night and IFR, not day VFR. I called the FAA and they said yes, that is correct! Do you need a compass to fly the pattern? Here is a copy of the document I was sent from a guy on another list. This is based on FAA's own guidance to their inspectors.
MINIMUM INSTRUMENT AND EQUIPMENT REQUIREMENTS
FOR POWERED AMATEUR BUILT EXPERIMENTAL AIRCRAFT
Introduction: The table below is intended to give the builder of amateur built experimental aircraft a ready reference for the instrument and equipment requirements for his aircraft. The builder should note that some items required by the FAR?s are described in the FAR?s as needing to be approved, but since there are no certification standards established for amateur built experimental aircraft no formal individual item approval, such as meeting a TSO (Technical Standard Order) or FAR Part 23, is required. However certain items must interface properly with ATC (Air Traffic Control), other aircraft, or other entities external to the aircraft. Transponders, communication radios, exterior lighting and ELT?s (Emergency Locator Transmitters) are examples of such equipment. Therefore, the builder can expect that the initial airworthiness inspection of his aircraft will require evidence that this type of equipment in the aircraft is acceptable to the FAA.
The Special Airworthiness Certificate issued for each amateur built experimental aircraft includes specific Operating Limitations. Per FAA Order 8130.2F the Operating Limitations state: ?After completion of Phase I flight testing, unless appropriately equipped for night and/or instrument flight in accordance with 91.205, this aircraft is to be operated under VFR, day only.? The FAR?s, FAA Order 8130.2F, and current FAA policy have been used in constructing the below amateur built experimental aircraft configuration requirements table.
THIS TABLE DOES NOT PROVIDE RECOMMENDATIONS FOR BEST PRACTICES. INSTALLING ONLY THE MINIMUM REQUIRED ITEMS MAY NOT BE PRUDENT OR SAFE.
By Owen C. Baker with appreciation to Richard E. Koehler.
MINIMUM INSTRUMENT AND EQUIPMENT REQUIREMENTS
FOR POWERED AMATEUR BUILT EXPERIMENTAL AIRCRAFT
DAY NIGHT DAY OR
FAR & ITEM DESCRIPTION (See Notes Below Table)
.....................................................VFR...VFR NIGHT...IFR
1. 91.205 (b) (1) Airspeed Indicator...NR...R...R
2. 91.205 (b) (2) Altimeter NR R R
3. 91.205 (b) (3) Magnetic Direction Indicator NR R R
4. 91.205 (b) (4) Tachometer for Each Engine NR R R
5. 91.205 (b) (5) Oil Pressure Gauge for Each Engine
Using a Pressure System NR R R
6. 91.205 (b) (6) Temperature Gauge for Each
Liquid Cooled Engine NR R R
7. 91.205 (b) (7) Oil Temperature Gauge for Each
Air Cooled Engine NR R R
8. 91.205 (b) (8) Manifold Pressure Gauge for
Each Altitude Engine NR R R
9. 91.205 (b) (9) Fuel Gauge Indicating Quantity of Fuel
In Each Tank NR R R
10. 91.205 (b) (10) Landing Gear Position Indicator, If Retractable NR R R
11. 91.205 (b) (11) Anti-Collision Light System -
(Small civil airplanes certified after 3/11/96) NR R R
12. 91.205 (b) (13) Approved Safety Belts With Metal to Metal
Buckles for Each Occupant (2 yrs or older) NR R R
13. 91.205 (b) (14) Approved Shoulder Harness for Each Front
Seat - For Small Civil Airplanes Manufactured After 7/18/78 NR R R
14. 91.205 (b) (15) ELT (If required by Sec. 91.207, i.e. >one seat
and >50 miles) AR AR AR
15. 91.205 (b) (16) Approved Shoulder Harness for Each Seat ?
Airplanes With 9 or Less Seats Manufactured After 12/12/86 NR R R
16. 91.205 (b) (17) Shoulder Harness for Each Seat For
Rotorcraft ? Manufactured After 9/16/92 NR R R
17. 91.205 (c) (2) Approved Position (navigation) Lights NR R R
18. 91.205 (c) (3) Anti-Collision Light System
(Systems installed after 8/11/71- see reference) NR R R
19. 91.205 (c) (5) Adequate Source of Electrical Energy for
Installed Equipment NR R R
20. 91.205 (c) (6) One Spare Set of Fuses or Three Fuses
of Each Kind Required, Must be Accessible to Pilot In Flight NR R R
21. 91.205 (d) (2) Two-Way Radio Communication System and
Navigational Equipment Appropriate to Ground Facilities Used NR NR R
22. 91.205 (d) (3) Gyroscopic Rate of Turn Indicator
(Some Exceptions, See Reference) NR NR R
23. 91.205 (d) (4) Slip-Skid Indicator NR NR R
24. 91.205 (d) (5) Sensitive Altimeter Adjustable for
Barometric Pressure, (See FAR 91.411, Altimeter System
Inspection Required Every 24 Calendar Months) NR NR R
25. 91.205 (d) (6) Clock Displaying Hours, Minutes, and Seconds ?
Sweep Second Pointer or Digital NR NR R
26. 91.205 (d) (7) Electrical Generator or Alternator
of Adequate Capacity NR NR R
27. 91.205 (d) (8) Gyroscopic Bank and Pitch Indicator
(Artificial Horizon) NR NR R
28. 91.205 (d) (9) Gyroscopic Direction Indicator
(Directional Gyro or Equivalent) NR NR R
29. 91.205 (e) DME Above FL 240 N/A N/A AR
30. 91.215, Transponder in Certain Airspace, (See FAR 91.413,
Inspection Required Every 24 Calendar Months) AR AR AR
Notes:
(1) AR = As Required, NR = Not Required, N/A = Not Applicable, R = Required
(2) A fourth flight operation category, Day (only) Instruments, is not included above.
ABEA Minimum Inst Requirements 7.doc 11/17/2005
Are you going to leave the compass off? Why not save weight and cost. I doubt you will get lost with a GPS, but to each his own. If it was not for my Dynon EFIS-10 I would NOT put a WWII compass in my panel that really is not that accurate. Don't get me wrong I like the esoteric aspect of a compass from my Boy Scout days and teaching "magnetic Dip" to private and instrument pilots as a CFI, but for VFR knowing your track is priceless, which the GPS does. It was back in the day all we had was tracking a NDB track or VOR radial, by heading and bracketing, but I am too lazy, GPS direct please. IFR, now that is a different story, which is reflected in the chart above. You have vectors and you still need to fly "headings" or track. G
