Looking for a tiny VSI

[danny_galaga]

Geez, I meant VSI! sorry guys, yes I do check the ASI and I believe it's a legal requirement to have it 

[facthunter]

Wasps can block the Pitot in no time. Be ready to fly a circuit without  a functioning ASI. IF this happens you are allowed to err on the fast side because it's unwise to err on the slow side. Re CHT's on Chipmunks with the usual motor  145 hp 10 Mk 2 with alloy heads they NEVER had a  CHT  nor did the 130 HP 1C with bronze heads.. Nev

[Bruce Tuncks]

We used to do this at my club with gliders. A flight with the ASI and Altimeter covered up. The instructor, sitting behind, had his instruments clear of course.

As Nev says,they generally  flew about 5 knots faster, which I reckon is the correct thing to do.

I never expected to do this for real, until one day I did a test flight for this guy who had connected his asi wrongly after an annual service. The slower you flew, the higher was the asi reading.

There were no problems , and we didn't use the altimeter much anyway because it is useless when landing out. I reckon I flew the circuit  about 10 knots faster than usual. We had an old ww2 strip which was more than long enough and the Mosquito had wonderful flap-brakes. 

There is nothing in the RAAus training like this, and I appreciate that the tandem seating of a glider makes it much easier to do than the side-by-side of a Jabiru, where you only have one asi.

If I were to lose the asi on a Jabiru, I reckon it would be similar but harder than with a glider because of the absence of airbrakes. I would like a really long runway for landing.

[facthunter]

You do have a motor to assist. Go back  to the S&L exercise which most don't fully "get" and fly the plane from low cruise to" a bit slow for your liking" a few times now and then.  Do the change slowly and assess the control feel and response and the air noise etc. Nev

[danny_galaga]

Thoughts on the VSI for flight testing?

[facthunter]

It's a "performance" instrument in some circumstances but you can derive the same information from the non digital altimeter with a minimum of mental gymnastics in a basic plane.  IF you have got one well and good but I wouldn't be spending great dollars thinking it was essential to normal flight. There's an IVSI (sensitive ie Instant) in most commercial Planes (uses a plus and minus needle).  I'm not impressed with digital readouts for altimeters and other performance instruments as RATE is just blurred numbers.  Nev

[danny_galaga]

Hmmmm, maybe I'll leave things as they stand then. No VSI 🙂

[Yenn]

I used to regard the VSI as being irrelevent and hardly ever looked at it. When I did instrument flying training way back in the seventies I was not very good at it.

A few years ago probably 2018 I did a flight review for GA and the instructor said we would do instrument flying. I told him of my disregard of the VSI and he said that an old Hurricane pilot had told him that the ASI was the most important instrument, because it gave an instantaneous indication of level change.

I did about an hour on instruments, making use of the VSI and while I was sweating a bit I managed to maintain control through turns, climbs and descents to specific headings and altitudes.

THat instrument I mentioned above is not only a VSI it has attitude and other things as well.

[facthunter]

The sensitive ones have a little vibrating electric motor in them to prevent hysteresis. You checked it by putting the hand mike on the glass face.   Limited Panel IFR is pretty tricky. No gyro's, bar the turn needle.   Nev

[Bruce Tuncks]

Vertical Speed Indication is necessary to thermal a glider. It needs to be compensated so that " stick lift" doesn't show as climb. 

I never found much use for it with power, except for when I was ( unsuccessfully ) trying to thermal the Jabiru. But the VSI is not compensated on the Jabiru, so this may have been the cause. On my model planes, the absence of compensation is a real problem. This was unexpected to me.

 

 

 

 

 

[Blueadventures]

43 minutes ago, Bruce Tuncks said:

Vertical Speed Indication is necessary to thermal a glider. It needs to be compensated so that " stick lift" doesn't show as climb. 

I never found much use for it with power, except for when I was ( unsuccessfully ) trying to thermal the Jabiru. But the VSI is not compensated on the Jabiru, so this may have been the cause. On my model planes, the absence of compensation is a real problem. This was unexpected to me.

 

 

 

 

 

The gliding skill can be used lining up cloud streets.  Did it between Mackay to Temora and mate was impressed in the reduced fuel usage just by remaining in the buoyant / lift air of the streets; therefore another use of the VSI in powered flying.

[danny_galaga]

You guys have the mad skillz. Me, I'll be happy just pootling around burning 3 litres an hour more than I should 😄