Comments on: Disjointed notes on my Gaspé trip

By: Ed Davies

Ed Davies — Thu, 03 Aug 2006 15:49:02 +0000

Re constant airspeed or constant altitude in lift or sink: clearly if you’re IFR or likely to be mixing with IFR traffic then holding constant altitude is important. In pure VFR circumstances, though, I really can’t see the point. More, constant altitude is harmful. It’s much harder to see another aircraft against the haze near the horizon than against the clear sky or the ground so if eveybody is moving up and down gently there’s more chance of early sightings.

Also, constant altitude is just about the most fuel inefficient plausible strategy. It results in you flying slowly in sinking air and quickly in rising air. Even if the airmass cancels out over the distance along your path the net effect is that you spend more time in the sink. Constant speed is better for this but the best strategy is to speed up in the sink and slow down in the lift. This, of course, causes even wider altitude excursions than flying at constant speed but, frankly, so what? (As long as the passengers are comfortable with the pitch changes, of course.)

Glider (sailplane) pilots spend a lot of time worrying about this sort of thing though it is now pretty widely understood that so long as you get the speed roughly right the details don’t really matter, particularly with modern high performance gliders. Where glider pilots have the advantage is that any half decent variometer will compensate for the extra sink caused by higher speed whereas an aeroplane VSI will not. If you try flying faster in sink in a typical aeroplane the extra sink due to the increased speed will cause the VSI to point further down causing you to fly faster, and so on.

Still, keeping constant speed or speeding up just a bit in sink will probably save you some fuel.

By: david

david — Wed, 02 Aug 2006 20:14:02 +0000

Rob: I’m interested in hearing more about the Thielert diesel mod — it’s my parachute (so to speak) for when 100LL is no longer available. You must get an incredible range with 48 gallons of Diesel at 5gph — using 100LL, I’m lucky to manage 400 miles without a fuel stop. My only reluctance, aside from the cost and the diesel stink, is that I’d lose over 100 lb of useful load; on the other hand, I’d fly faster at altitude, and with the bigger range, I could get back the load by carrying less fuel.

As for turbulence, I find the Warrior much more stable than the Cessna 172, which is the only other plane I have a lot of time in. I went flying once in a friend’s Aztec in turbulence, but I found the yaw (from the big tail) very hard to stomach.

By: Rob Croucher

Rob Croucher — Wed, 02 Aug 2006 19:36:38 +0000

Some interesting thoughts here. I fly a diesel (thielert) Warrior, although I trained on a Grumman AA5. Since changing aircraft types I have found it quite difficult, the Piper appears to be more affected by even small bumps, turbulence or thermals and mostly it is just uncomfortable, but there are occasions, more frequently lately where they are starting to affect my flying because I am concerned for the stability of the craft. After consulting the relative tech docs it appears the warrior has an additional 40 square feet of wing surface over and above the grumman and I wonder if this is the only reason??

As someone who appears to have a good amount of hours on this type (excepting the engine mod ofcourse!) What are your impressions about this, is it usual for turbulence to be noticed more??…. any suggestions for the best ways to deal with it etc would be nice to hear.

Thanks in advance

Rob Croucher

By: Marc-Olivier Mehu

Marc-Olivier Mehu — Wed, 02 Aug 2006 12:57:06 +0000

Nice to see some new stuff from you. Regarding circuit joining procedures you said that joining straight-in final is not legal in Canada. I agree that it is poor airmanship but unfortunately I thing that it is allowed from a strictly legal standpoint.

The CARs (legal reference in Canada) dont say much about circuit joining procedures (left turns, safe joining procedures).

The other reference albeit not a legal one, the TC AIM allows for straight-in joining for some uncontrolled aerodromes:

RAC 4.5.1

(vi) Aerodromes within an MF area when airport advisory information is available: Aircraft may join the circuit pattern straight-in or at 45˚ to the downwind leg or straight-in to the base or final legs (Figure 4.1). Pilots should be alert for other VFR traffic entering the circuit at these positions and for IFR straight-in or circling approaches.

Bad Airmanship, sure, illegal, only if you consider 602.01 (Reckless or Negligent Operation of Aircraft)

Keep up good work,

Marc-Olivier