Ed_Wischmeyer
Well Known Member
There have been a few discussions on VAF about the de/merits of constant speed props for RVs, and this brief travelogue is about the advantages of a constant speed prop on a long trip, like Savannah, GA to North Las Vegas, NV.
New Mexico has a thriving turbulence industry, and on this trip (so far) I’ve seen the G-meter range from 0.6 – 1.5 G as the plane hits sudden up and down drafts. Not much fun, and several times I’ve made comfort stops because I was tired of getting bounced around – not the customary kind of comfort stop. And West Texas is a close second for turbulence…
With this turbulence comes up and down drafts. The good news about a constant speed prop is that you don’t have to retard throttle in an updraft to keep the prop from overspeeding as the autopilot pushes the nose over, and similarly add power in a downdraft. How frisky were the up and downdrafts? At my normal 65% power, 8 GPH, I see 151-153 KTAS. Today, with constant power setting, I saw – are you ready for this? – 137 to 170 KTAS in the up and downdrafts. But I didn’t have to touch the throttle!
For those of you with mountain flying experience, the temperature/dew point spread is an indicator of virga with potentially damaging dry microbursts. Today was virga city, all over the sky, but the good news about the over-development (as the sailplane folks say) is that there was lots of cloud shade. When I landed at Page, AZ, the temperature/dew point spread was 80°. This is twice the spread that is conducive to dry microbursts.
At Gallup, NM, a comfort stop, density altitude was 9,100 feet. The constant speed prop let the little engine that could do its thing, and that was a good thing. After breaking ground, the RV-9A skimmed the runway for a while before deciding to seriously aviate. A fixed pitch prop would have been more, well, interesting…
Lotsa good, friendly stops along the way: Athens, GA; Meridian, MS with the free hot dogs; Lubbock, TX where the Cotton Court boutique hotel is spectacular and affordable; Belen, NM with great service; Gallup, NM was friendly even though I didn’t need gas; and Classic Aviation in Page, AZ, where I am now.
Way out west, ADS-B weather is a sometimes thing whereas XM is all the time. Having only ADS-B was not a serious inconvenience, though.
A few lessons learned for really long trips – in this case six relatively short days of flying outbound, total trip duration of two weeks or however long I go, wherever it is that I’m going on the way home. First, if you’re staying overnight, hotel price and convenience will completely overshadow avgas price. Rental cars are ridiculously expensive these days.
IMSAFE does not include hydration, but it is so important. Drink water the day before, not necessarily the night before, and sip water during the flight. Do not tank up right before takeoff for obvious reasons.
Be prepared for all kinds of surface winds. At Lubbock, winds were 17G24, 30° to the runway, and the locals were not impressed. At Gallup, the winds were reported variable at 3G18, which must have been a typo. There are times that you’ll need your A game with no warning.
And when you’re sitting in the RV, getting beat up by the turbulence, you’ll have plenty of time to think of clever anecdotes to bash Cessna 172s…
New Mexico has a thriving turbulence industry, and on this trip (so far) I’ve seen the G-meter range from 0.6 – 1.5 G as the plane hits sudden up and down drafts. Not much fun, and several times I’ve made comfort stops because I was tired of getting bounced around – not the customary kind of comfort stop. And West Texas is a close second for turbulence…
With this turbulence comes up and down drafts. The good news about a constant speed prop is that you don’t have to retard throttle in an updraft to keep the prop from overspeeding as the autopilot pushes the nose over, and similarly add power in a downdraft. How frisky were the up and downdrafts? At my normal 65% power, 8 GPH, I see 151-153 KTAS. Today, with constant power setting, I saw – are you ready for this? – 137 to 170 KTAS in the up and downdrafts. But I didn’t have to touch the throttle!
For those of you with mountain flying experience, the temperature/dew point spread is an indicator of virga with potentially damaging dry microbursts. Today was virga city, all over the sky, but the good news about the over-development (as the sailplane folks say) is that there was lots of cloud shade. When I landed at Page, AZ, the temperature/dew point spread was 80°. This is twice the spread that is conducive to dry microbursts.
At Gallup, NM, a comfort stop, density altitude was 9,100 feet. The constant speed prop let the little engine that could do its thing, and that was a good thing. After breaking ground, the RV-9A skimmed the runway for a while before deciding to seriously aviate. A fixed pitch prop would have been more, well, interesting…
Lotsa good, friendly stops along the way: Athens, GA; Meridian, MS with the free hot dogs; Lubbock, TX where the Cotton Court boutique hotel is spectacular and affordable; Belen, NM with great service; Gallup, NM was friendly even though I didn’t need gas; and Classic Aviation in Page, AZ, where I am now.
Way out west, ADS-B weather is a sometimes thing whereas XM is all the time. Having only ADS-B was not a serious inconvenience, though.
A few lessons learned for really long trips – in this case six relatively short days of flying outbound, total trip duration of two weeks or however long I go, wherever it is that I’m going on the way home. First, if you’re staying overnight, hotel price and convenience will completely overshadow avgas price. Rental cars are ridiculously expensive these days.
IMSAFE does not include hydration, but it is so important. Drink water the day before, not necessarily the night before, and sip water during the flight. Do not tank up right before takeoff for obvious reasons.
Be prepared for all kinds of surface winds. At Lubbock, winds were 17G24, 30° to the runway, and the locals were not impressed. At Gallup, the winds were reported variable at 3G18, which must have been a typo. There are times that you’ll need your A game with no warning.
And when you’re sitting in the RV, getting beat up by the turbulence, you’ll have plenty of time to think of clever anecdotes to bash Cessna 172s…
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