variable Prop
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variable Prop
Was wondering if to fit a variable prop to our Zenair 601HD. An 80HP rotax is fitted and a 3 blade warpdrive prop at present . Im looking for shorter takeoff and higher cruise speed (or same at lower RPM). Looked at a few different ones but wondered what others think before I move forward. Any ideas/ recommendations from anyone?
Adrian
G-ZAIR
Adrian
G-ZAIR
- Kevin Dilks
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I have an arplast PV50 that replaced a fixed pitch prop on my MCR. It has made a big difference to the take off roll and climb rate plus an additional 10kn in the cruse.
http://www.lts-limited.co.uk/arplast.php
If you are around the midlands you are welcome to have a look / come for a ride.
Rod1
http://www.lts-limited.co.uk/arplast.php
If you are around the midlands you are welcome to have a look / come for a ride.
Rod1
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In the March 2010 "Light Aviation", Francis Donald tests an Aeroprakt A22-LL Foxbat fitted with a rather expensive Airmaster VP prop. He said the prop allowed maximum power to be used at take-off, giving a short take-off and an impressive rate of climb. The Airmaster let the Rotax 912ULS run at 4,600 rpm at cruise, rather than the 5,100 rpm that a fixed prop would need. This resulted in a cruise burn of 12-13 lph rather than 15-16 lph, and a cruise mode that "was significantly quieter and more relaxed".
Francis concluded: "The VP prop? If price were no object, then yes, for that relaxed '5th gear' cruise mode. But in the real world of cost versus benefit, the ground adjustable prop would do me fine".
Perhaps the Airmaster is an unnecessarily costly option for a STOL aircraft with a Vne of only 120mph (not knots!); and perhaps the cheaper Woodcomp prop or the Arplast PV50 would have saved a few bob. However, it seems to me that if a VP prop were available at a really affordable price, then almost any aircraft that could fly above, say, 70mph could reap its benefits.
These benefits include: shorter take-off, faster-climb, quieter and more economical cruise, and a quicker engine response at go-around. Shorter take-off means that (i) you are less likely to hit the hedge at the runway's end and (ii) more short strips would become accessible. The quicker climb means that the aircraft gets away more quickly from plane-hating nimbys. The quiet cruise means less annoyance for the same nimbys and less strain on both engine and passengers. The greater economy means that with luck, the purchase cost could be recoverable at least once over the aircraft's lifetime; and the extra power at go-around means a huge safety margin.
All these benefits suggest that promoting cheaper VP props should be an LAA priority; yet one reason that current offerings are so expensive is that the market is small and profit-margins must be maintained. But if a good VP prop were to become available for between £1,000 and £2,000, most LAA fliers would be very tempted to fit one.
I'll return to a favourite of mine: the V-Prop, http://www.v-prop.com/. It's a self-powering, self-adjusting VP prop produced in Germany by the makers of the Silence Twister. To me, this design is so ingenious that I would love to fit one (to my ARV Super2). However, although this propeller is widely used throughout the continental Europe, the manufacturers have decided NOT to import it into the UK, because of, to quote Francis again, "an over-burdensome UK regulatory system".
Would it not be desirable for Francis to allow the V-Prop to be trialled experimentally in this country, so that LAA members might take advantage of this excellent propeller?
Francis concluded: "The VP prop? If price were no object, then yes, for that relaxed '5th gear' cruise mode. But in the real world of cost versus benefit, the ground adjustable prop would do me fine".
Perhaps the Airmaster is an unnecessarily costly option for a STOL aircraft with a Vne of only 120mph (not knots!); and perhaps the cheaper Woodcomp prop or the Arplast PV50 would have saved a few bob. However, it seems to me that if a VP prop were available at a really affordable price, then almost any aircraft that could fly above, say, 70mph could reap its benefits.
These benefits include: shorter take-off, faster-climb, quieter and more economical cruise, and a quicker engine response at go-around. Shorter take-off means that (i) you are less likely to hit the hedge at the runway's end and (ii) more short strips would become accessible. The quicker climb means that the aircraft gets away more quickly from plane-hating nimbys. The quiet cruise means less annoyance for the same nimbys and less strain on both engine and passengers. The greater economy means that with luck, the purchase cost could be recoverable at least once over the aircraft's lifetime; and the extra power at go-around means a huge safety margin.
All these benefits suggest that promoting cheaper VP props should be an LAA priority; yet one reason that current offerings are so expensive is that the market is small and profit-margins must be maintained. But if a good VP prop were to become available for between £1,000 and £2,000, most LAA fliers would be very tempted to fit one.
I'll return to a favourite of mine: the V-Prop, http://www.v-prop.com/. It's a self-powering, self-adjusting VP prop produced in Germany by the makers of the Silence Twister. To me, this design is so ingenious that I would love to fit one (to my ARV Super2). However, although this propeller is widely used throughout the continental Europe, the manufacturers have decided NOT to import it into the UK, because of, to quote Francis again, "an over-burdensome UK regulatory system".
Would it not be desirable for Francis to allow the V-Prop to be trialled experimentally in this country, so that LAA members might take advantage of this excellent propeller?
formerly "arriviste" (ARV-ist!)
Francis is in a difficult position these days with new developments like the V-prop.
Whether we like it or not the LAA has become a quasi-regulatory body. So the engineering function is much more of an approval body than an engineering resource to develop things.
So it is now down to the developer or some other interested body to submit engineering analysis to demonstrate fitness for purpose to the LAA - who will then approve trialling etc. This is naturally the expensive and difficult bit....
Years ago I tried something similar with the Warp Drive propellers - which then were very new. Without an analysis from the manufacturer the costs of doing that work in the UK with a third party were scary, and more to the point not recoverable from a sole agency agreement or something similar.
Such is the state of things in the UK now. Possibly EASA will mean improved access to some of these things on the basis that someone somewhere in the EU has already approved it, hopefully we'll find out soon.
Whether we like it or not the LAA has become a quasi-regulatory body. So the engineering function is much more of an approval body than an engineering resource to develop things.
So it is now down to the developer or some other interested body to submit engineering analysis to demonstrate fitness for purpose to the LAA - who will then approve trialling etc. This is naturally the expensive and difficult bit....
Years ago I tried something similar with the Warp Drive propellers - which then were very new. Without an analysis from the manufacturer the costs of doing that work in the UK with a third party were scary, and more to the point not recoverable from a sole agency agreement or something similar.
Such is the state of things in the UK now. Possibly EASA will mean improved access to some of these things on the basis that someone somewhere in the EU has already approved it, hopefully we'll find out soon.
Pete Morris
013242
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Fair comment; although ever since 1992 when the EU's single market finally became established, there is supposed to have been "free movement of goods". What is the point of having the legal right to import, say, the V-Prop, if UK authorities still require you to test it to destruction before using it?gasax wrote:Francis is in a difficult position these days with new developments like the V-prop. Whether we like it or not the LAA has become a quasi-regulatory body. ... So it is now down to the developer or some other interested body to submit engineering analysis to demonstrate fitness for purpose to the LAA - who will then approve trialling etc. This is naturally the expensive and difficult bit .... Possibly EASA will mean improved access to some of these things on the basis that someone somewhere in the EU has already approved it, hopefully we'll find out soon.
(I understand that some Silence Twisters in Germany have the V-prop fitted; couldn't the LAA have a gander at some of these?)
Much as I fancy the V-Prop idea, it still fails to meet the requirement of cheapness, given its current price of €3,300. So here's a way to produce aA simpler prop that that may not be perfect but would still be miles better than a fixed pitch prop: install a spring-loaded 2-speed prop. It would be set on the ground to fine; and then, after take-off and climb out, the pilot would operate a mechanical release to let the blades twist to coarse. The blades would stay in this coarse position for the rest of the flight, yielding better thrust on less rpm. I suspect that it would not be too tricky for a manufacturer like, say, Arplast, to modify their ECOPROP to become such a 2-speed device.
Last edited by Trevor Lyons on Thu Apr 15, 2010 7:01 am, edited 1 time in total.
formerly "arriviste" (ARV-ist!)
- mikehallam
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Though not quite the solution you're studying, my a/c (S6-116 with Rotax 912) came with two blade WarpDrive prop. Ground adjustable.
To be honest, having tried a few easy to try [FREE] small setting alterations off a grass strip, the only noticeable difference was the cruise revs. For climb and t/off I couldnt detect any real difference.
The engine power curve is relatively flat where it matters and Rotax aver they're quite happy with continuous high rev's, so plonking along in 'overdrive' may be worse for wear !
Perhaps for really slippery light planes the illusion of VP surpasses the cost.
mike.
To be honest, having tried a few easy to try [FREE] small setting alterations off a grass strip, the only noticeable difference was the cruise revs. For climb and t/off I couldnt detect any real difference.
The engine power curve is relatively flat where it matters and Rotax aver they're quite happy with continuous high rev's, so plonking along in 'overdrive' may be worse for wear !
Perhaps for really slippery light planes the illusion of VP surpasses the cost.
mike.
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My ARVSuper2 with 90bhp MidWest rotary has an excellent ground-adjustable Arplast ECOPROP. When I was operating from Derby, a short-strip grass field with obstacles on most approaches, the take-off performance was a bit marginal when 2-up and at MAUW. I adjusted the ECOPROP to make it a bit finer, which transformed the take-off; but the cruise revs are now higher than is ideal. So I remain convinced that, even if any improvement is marginal, a V-P prop will invariably be better than a fixed-pitch prop (provided the former is neither too expensive nor too heavy).mikehallam wrote:My a/c (S6-116 with Rotax 912) came with two blade WarpDrive prop. Ground adjustable. To be honest, having tried a few easy to try [FREE] small setting alterations off a grass strip, the only noticeable difference was the cruise revs. For climb and t/off I couldnt detect any real difference.
formerly "arriviste" (ARV-ist!)
WoodComp propellor ptich
Hi Does anyone know what balde angle constitutes "fine pitch" on the Woodcomp Klassic 3 balde prop as fitted to SportCruisers?
Or perhaps the range of pitch that the VP version is adjustable through?
Peter
Or perhaps the range of pitch that the VP version is adjustable through?
Peter
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just seen this from the Twister UK home page, it quotes the are an agent for the V-prop
http://www.silence-twister.co.uk/silenc ... peller.htm
http://www.silence-twister.co.uk/silenc ... peller.htm
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The last time I spoke to the guys at Twister, some time ago, they said that even though the amazing V-Prop is up and running in most European countries, they don't propose to import it here. Apparently, it isn't worth their while jumping through the hoops that the LAA have set in order for the V-Prop to be approved for the UK.Will Greenwood wrote:Just seen this from the Twister UK home page, it quotes they are agents for the V-prop.
(I have ranted on this topic in the past; and I still feel that the LAA's requirements may amount to an unfair obstacle to inter-Member State trade within the EU. A trip to the European Court of Justice is perhaps OTT; but a referral to the Ombudsman costs nothing and might settle the issue. After all, if the Ombudsman advised that the V-Prop ought to be allowed in the UK, the LAA wouldn't need to fret about any third-party liability on this score).
formerly "arriviste" (ARV-ist!)
The LAA’s role in approval is going to have to adapt. When the full range of ELA1 aircraft appear with EASA approval some will contain bits which the LAA have insisted are changed or modified on the equivalent kit version. Even the CAA is not immune. The new Tecnam twin has an EASA c of a and is approved for use of E10 Mogas. CAA rules forbid use of E rated mogas and but legal advice is in favor of EASA!
What you need is a factory built Twister with a Vprop and EASA ELA1 paperwork, should make for an interesting discussion…
Rod1
What you need is a factory built Twister with a Vprop and EASA ELA1 paperwork, should make for an interesting discussion…
Rod1
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