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VP prop, good idea? which one?

 
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graeme bird



Joined: 15 Jul 2010
Posts: 434

PostPosted: Tue Jan 10, 2012 9:44 am    Post subject: VP prop, good idea? which one? Reply with quote

So, in the shake down flight we were getting 140kts indicated at 5700 (at) 2000ft on a 912ULS but the ASI is reading a bit high. I presume a VP prop would give a better take off and climb, quieter, maybe faster cruise particularly in thinner air. Am I right and which to go for?
Woodcomp is significantly cheaper and I am told the wood is more absorbent of vibrations and less stiff.
Is the CS controller worth having or is manual variable just as good?
Is it worth being able to feather it?

I intend to fly on my FP warp drive initially but it would suit me to buy the next prop now if thats the sensible thing to do.

Advice appreciated.

See you all at the dinner.


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Graeme Bird
kit4 (Wagstaff) TBD
Kit3 G-CLXU (Gregory) mono 914 xs Woodcomp
Kit2 G-PATS - (kesterton) Mono Classic 912 warpdrive
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graeme bird



Joined: 15 Jul 2010
Posts: 434

PostPosted: Tue Jan 10, 2012 10:46 am    Post subject: Re: VP prop, good idea? which one? Reply with quote

oh dear, searching back through the historical records I see I might have kicked a hornets nest. Just tell me about the benefits of the CS prop then rather than the comparison.

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Graeme Bird
kit4 (Wagstaff) TBD
Kit3 G-CLXU (Gregory) mono 914 xs Woodcomp
Kit2 G-PATS - (kesterton) Mono Classic 912 warpdrive
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PostPosted: Tue Jan 10, 2012 11:41 am    Post subject: VP prop, good idea? which one? Reply with quote

Hi Graham,
VP or CS props.
1 Better take off performance
2 Or better cruise performance. Depends what pitch you set it at.
3 Much greater overall flexibility and all round performance.

Graham, by the way max continuous cruise on the Rotax 4 stroke series of
engines is 5500 RPM not 5700RPM

Pete

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rlborger(at)mac.com
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PostPosted: Tue Jan 10, 2012 12:01 pm    Post subject: VP prop, good idea? which one? Reply with quote

Greame,

Yes, you may have done just that.

I don't know how you have your current prop set. If it is set for a compromise between climb and cruise, as most are, then a C/S prop should allow you to take off in a shorter distance with superior climb performance and then allow you to cruise at a higher speed for the same fuel flow. Or you can obtain the same cruise performance at a lower fuel flow. If your prop is set for climb performance then the C/S prop will equal that performance and provide much better cruise performance. If you have your prop adjusted for cruise performance then the C/S prop will provide much better takeoff and climb performance.

I have an Airmaster AP332 with AP200 controller. I consider their products to be of the highest quality and have found Martin to provide excellent support.

Others seem to be quite satisfied with their own choices so you can go on from there.

Blue skies & tailwinds,
Bob Borger
Europa XS Tri, Rotax 914, Airmaster C/S Prop.
Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP
3705 Lynchburg Dr.
Corinth, TX 76208-5331
Cel: 817-992-1117
rlborger(at)mac.com

On Jan 10, 2012, at 12:46 PM, graeme bird wrote:

Quote:


oh dear, searching back through the historical records I see I might have kicked a hornets nest. Just tell me about the benefits of the CS prop then rather than the comparison.

--------
Graeme Bird
G-UMPY
Mono Classic/XS FWFD 912ULS/Warp drive FP
Just Test Flying to obtain permit


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graeme bird



Joined: 15 Jul 2010
Posts: 434

PostPosted: Tue Jan 10, 2012 12:05 pm    Post subject: Re: VP prop, good idea? which one? Reply with quote

Thanks Pete, yes I know its 5800 for a brief period only (5min) - but thats long enough to take a speed reading.

Why did you say TO performance OR cruise, surely you improve both by setting fine for take off and course for cruise. What speed would you expect in the cruise?

Regards


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Graeme Bird
kit4 (Wagstaff) TBD
Kit3 G-CLXU (Gregory) mono 914 xs Woodcomp
Kit2 G-PATS - (kesterton) Mono Classic 912 warpdrive
Kit 1 G-UMPY - Mono Classic/XS 912S, Woodcomp G(@)gdbmk.co.uk
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Rocketman



Joined: 07 Sep 2010
Posts: 87
Location: USA, Earth

PostPosted: Tue Jan 10, 2012 12:14 pm    Post subject: VP prop, good idea? which one? Reply with quote

Graeme,

I bought an Air Master, complete with CS controller, right off and
haven't looked back. Great performance on both ends and in the middle,
too.

Jeff - Baby Blue

On 1/10/2012 11:44 AM, graeme bird wrote:
Quote:


So, in the shake down flight we were getting 140kts indicated at 5700 (at) 2000ft on a 912ULS but the ASI is reading a bit high. I presume a VP prop would give a better take off and climb, quieter, maybe faster cruise particularly in thinner air. Am I right and which to go for?
Woodcomp is significantly cheaper and I am told the wood is more absorbent of vibrations and less stiff.
Is the CS controller worth having or is manual variable just as good?
Is it worth being able to feather it?

I intend to fly on my FP warp drive initially but it would suit me to buy the next prop now if thats the sensible thing to do.

Advice appreciated.

See you all at the dinner.

--------
Graeme Bird
G-UMPY
Mono Classic/XS FWFD 912ULS/Warp drive FP
Just Test Flying to obtain permit


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PostPosted: Tue Jan 10, 2012 2:51 pm    Post subject: VP prop, good idea? which one? Reply with quote

On Jan 10, 2012, at 10:46 AM, graeme bird wrote:

Quote:


oh dear, searching back through the historical records I see I might
have kicked a hornets nest. Just tell me about the benefits of the
CS prop then rather than the comparison.

While I generally keep my distance from hornets' nests, as I've been
in prop selection mode, I will pass on the notion that some FP prop
manufacturers tout their products ability to adjust pitch (to a
significant degree) in accordance w/ load and forward airspeed...i.e.,
their props take a thinner bite in slow speed/high power situations,
and a thicker bite at cruise speed and cruise power settings. I write
"to a significant degree", but do not intend to suggest that such a FP
prop would provide CS performance.

My recent inquiry about who owns N108EA stems from my seeing it on
the Prince prop website gallery.

Check out:

http://princeaircraft.com/default.aspx and

http://www.neuform-propellers.com/index.php?f=1&lang=en&site=Propeller/Contact%20us

My interest in a ground adjustable FP prop stems from cost
considerations, risk of prop strike during initial monowheel ops, and
personal lack of experience flying behind a CS prop (thus affecting
cockpit workload during initial flight tests).

Fred
A194


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PostPosted: Tue Jan 10, 2012 3:42 pm    Post subject: VP prop, good idea? which one? Reply with quote

Graeme, As others have said it's a bit like having 5 gears on a car rather than going everywhere in third. Overall performance is transformed. But there is a further advantage: The constant speed element goes a long way to stop you overspeeding the engine, which can be an expensive or even very serious mistake. If you are distracted when operating at full power and have to descend to avoid something or are playing about doing unusual attitudes or aerobatics or whatever, it isn't difficult to overspeed with a fixed pitch prop, but a CS prop largely prevents that.
Unless you have glider wings I would not contemplate a feathering prop. The theoretical advantage of being able to glide a bit further in the event of an engine failure is for me heavily outweighed by the possibility or indeed probability that you will end up trying to land with the prop still feathered, which will substantially increase the ground run. There is a marked difference in landing withe prop fully coarse compared with fully fine, let alone feathered, and I guess it might double the length of field you need to land without damage.
Regards, David Joyce, G-XSDJ
Sent from my iPad

On 10 Jan 2012, at 17:44, "graeme bird" <graeme(at)gdbmk.co.uk> wrote:

Quote:


So, in the shake down flight we were getting 140kts indicated at 5700 (at) 2000ft on a 912ULS but the ASI is reading a bit high. I presume a VP prop would give a better take off and climb, quieter, maybe faster cruise particularly in thinner air. Am I right and which to go for?
Woodcomp is significantly cheaper and I am told the wood is more absorbent of vibrations and less stiff.
Is the CS controller worth having or is manual variable just as good?
Is it worth being able to feather it?

I intend to fly on my FP warp drive initially but it would suit me to buy the next prop now if thats the sensible thing to do.

Advice appreciated.

See you all at the dinner.

--------
Graeme Bird
G-UMPY
Mono Classic/XS FWFD 912ULS/Warp drive FP
Just Test Flying to obtain permit




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John Wighton



Joined: 18 May 2010
Posts: 241

PostPosted: Wed Jan 11, 2012 12:53 am    Post subject: Re: VP prop, good idea? which one? Reply with quote

I would like David to validate his last comment - field length dependent upon prop pitch when stopped.

When the prop is turning: The fine pitch gives lower residual thrust, hence field length is potentially decreased. Feathering is not an option when engine is working.

When the prop is stopped: There is a reduction in drag when the prop pitch is set feathered but this should not alter the field length used for landing? Arguably there is slightly lower drag when feathered, but this is negligible to the total drag of the a/c in landing config.

Sorry to highjack the thread but this may be important for us with feathering props if in a forced landing situation - tinkering with the feathering switch may not be the most efficient use of our time at that phase of the flight!

I have the Airmaster AP332 with AP200 controller setup and recommend it.


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PostPosted: Wed Jan 11, 2012 1:20 am    Post subject: VP prop, good idea? which one? Reply with quote

HI Graham,
What I had meant to infer was that the fixed pitch props work ideally for
cruise OR take off, depending on how you set them. They are a compromise
every where else.
Sorry for the confusion. It must have been the wine??

Pete

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richard collings



Joined: 08 Jul 2011
Posts: 73
Location: warwickshire england

PostPosted: Wed Jan 11, 2012 3:07 am    Post subject: VP prop, good idea? which one? Reply with quote

Hi Graeme

I think you have by now got the technical reasons for VP props over fixed, I
have fitted a Woodcomp SR3000 in preference to other types because its made
in the EU, good service back up is provided by the agent in Leicester and at
the agents suggestion I am controlling it with a Smart Avionics controller
which is UK made. I have also fitted a manifold pressure sensor so manifold
pressure is displayed on the same unit negating the need for a separate
gauge.
I have the done the grand total of 50min test running so far so can't speak
on durability etc but no complaints so far.
Regards Richard
G-CGZV
---


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PostPosted: Wed Jan 11, 2012 3:07 am    Post subject: VP prop, good idea? which one? Reply with quote

John, I can reply in two ways. Firstly in practical terms if you haven't tried it you should. There is a really noticeable difference in how quickly you slow down with the engine idling and the prop either in it's normal fine mode or fully coarse.
Alternatively looking at things from a theoretical viewpoint, the total drag for my DG300 glider at optimum glide angle(1:42) is around15 to 20lbs, (dividing AUW by 42) at around 60kts. For my mono at it's best glide angle of 1:12 at 60 kts it is around 80 to 100 lbs. Now if you stick your hand out of your car window going down the road at 60 kts/70mph and make it 'fully fine' the force on your hand is something more than 10lbs. Imagine your hand enlarged to the dimensions of three prop blades and you have accounted for much of the difference in drag of my glider and my Europa!
Having the engine idling doesn't make too much odds. At 1600 rpm a typical fine pitch tip angle of 20 degrees is equivalent to 9 kts. air flow. In fact it is worse than that if you have warp drive blades or indeed most other prop blades seen on Europas, which have low blade twist, which means that the central and inner portions of the blades are producing significantly lower air flow rates.
So my thesis is that an idling or stationary prop is responsible for a high proportion of drag (admittedly somewhat lower if you have all those extra wheels!!), and trying to slow down with the prop feathered is rather like trying to land a glider without air brake - you can float in ground effect down a long field until stopped by the far hedge!
Hope that all makes sense! Happy landings, David Joyce, G-XSDJ
Sent from my iPad

On 11 Jan 2012, at 08:53, "John Wighton" <john(at)wighton.net> wrote:

Quote:


I would like David to validate his last comment - field length dependent upon prop pitch when stopped.

When the prop is turning: The fine pitch gives lower residual thrust, hence field length is potentially decreased. Feathering is not an option when engine is working.

When the prop is stopped: There is a reduction in drag when the prop pitch is set feathered but this should not alter the field length used for landing? Arguably there is slightly lower drag when feathered, but this is negligible to the total drag of the a/c in landing config.

Sorry to highjack the thread but this may be important for us with feathering props if in a forced landing situation - tinkering with the feathering switch may not be the most efficient use of our time at that phase of the flight!

I have the Airmaster AP332 with AP200 controller setup and recommend it.

--------
John Wighton
Europa XS trigear G-IPOD




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PostPosted: Wed Jan 11, 2012 3:39 am    Post subject: VP prop, good idea? which one? Reply with quote

Having just been looking back through this rather long thread I am tempted to add a PS in relation to Fred Klein's comment about CS props and work load. Once you have your head round how a CS prop works, I would argue that they actually decrease the workload, rather than the reverse. My (Mark Burton smart Avionics controller - but I guess others work very similarly) prop controller has automatic and manual modes. In auto simply pressing a button will cycle through 'Take off', 'Climb' and 'cruise' settings. The target rpm for each mode can be adjusted but will stay the way you last set it unless you do something about it. So in practice, I press the button to change from T/O to Climb at the same time as I pull flaps up, and press the button again to change to cruise when I level out into some sort of cruise. There is no need to be constantly checking rpm as the controller does that for you, so you can spend 99+% of your time looking out and avoiding other circuit traffic. Much of what you may have read about the importance of matching rpm to manifold pressure is simply not applicable to Rotax engines. They tolerate any combination of rpm/manifold pressure, and in practice you can choose to cruise at 4800/75% or 5300/60%power or whatever.
Regards, David Joyce, G-XSDJ
Sent from my iPad

On 11 Jan 2012, at 11:35, David Joyce <davidjoyce(at)doctors.org.uk> wrote:

Quote:


John, I can reply in two ways. Firstly in practical terms if you haven't tried it you should. There is a really noticeable difference in how quickly you slow down with the engine idling and the prop either in it's normal fine mode or fully coarse.
Alternatively looking at things from a theoretical viewpoint, the total drag for my DG300 glider at optimum glide angle(1:42) is around15 to 20lbs, (dividing AUW by 42) at around 60kts. For my mono at it's best glide angle of 1:12 at 60 kts it is around 80 to 100 lbs. Now if you stick your hand out of your car window going down the road at 60 kts/70mph and make it 'fully fine' the force on your hand is something more than 10lbs. Imagine your hand enlarged to the dimensions of three prop blades and you have accounted for much of the difference in drag of my glider and my Europa!
Having the engine idling doesn't make too much odds. At 1600 rpm a typical fine pitch tip angle of 20 degrees is equivalent to 9 kts. air flow. In fact it is worse than that if you have warp drive blades or indeed most other prop blades seen on Europas, which have low blade twist, which means that the central and inner portions of the blades are producing significantly lower air flow rates.
So my thesis is that an idling or stationary prop is responsible for a high proportion of drag (admittedly somewhat lower if you have all those extra wheels!!), and trying to slow down with the prop feathered is rather like trying to land a glider without air brake - you can float in ground effect down a long field until stopped by the far hedge!
Hope that all makes sense! Happy landings, David Joyce, G-XSDJ
Sent from my iPad

On 11 Jan 2012, at 08:53, "John Wighton" <john(at)wighton.net> wrote:

>
>
> I would like David to validate his last comment - field length dependent upon prop pitch when stopped.
>
> When the prop is turning: The fine pitch gives lower residual thrust, hence field length is potentially decreased. Feathering is not an option when engine is working.
>
> When the prop is stopped: There is a reduction in drag when the prop pitch is set feathered but this should not alter the field length used for landing? Arguably there is slightly lower drag when feathered, but this is negligible to the total drag of the a/c in landing config.
>
> Sorry to highjack the thread but this may be important for us with feathering props if in a forced landing situation - tinkering with the feathering switch may not be the most efficient use of our time at that phase of the flight!
>
> I have the Airmaster AP332 with AP200 controller setup and recommend it.
>
> --------
> John Wighton
> Europa XS trigear G-IPOD
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=363021#363021
>
>
>
>
>
>
>
>
>
>







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John Wighton



Joined: 18 May 2010
Posts: 241

PostPosted: Wed Jan 11, 2012 4:32 am    Post subject: Re: VP prop, good idea? which one? Reply with quote

David,
Thanks for the reply/description. Having been an aeronautical engineer for 30 years l appreciate both the theoretical and practical analysis of a problem. Clearly you have a heap more experience in the practical sense, especially w.r.t. Europa flying.

I have at hand a bunch of tools (including Fluid-Dynamic Lift and Drag by Hoerner/Borst, CFD programs, etc) from which l would happily spend hours/days/weeks quantifying this discussion. But that will have to wait until l finish this pesky A380 work on my desk right now.

A rough calc ((at)50kt landing to standstill), along the lines of your suggestion, reveals a flat plate drag load of about 96 lbf for the fine (zero degrees in fact) pitched prop prop (4lbf for the feathered prop). This will reduce quickly with the square of the speed ((at)25 kts max load is approx 24 lbf). The proportion of total drag during the ground run will depend on a heap of stuff (tyre pressures, ground friction), etc.

So unbraked l think you have a point. With normal (or higher) braking l think the difference will be a lot less (as prop drag << total drag).

Hope to see you at some of the club events/trips this year.


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PostPosted: Wed Jan 11, 2012 5:50 am    Post subject: VP prop, good idea? which one? Reply with quote

John, I envy yoursophisticated tools! Once firmly on the ground then certainly braking is important, but I guess it is bleeding off the speed from 60kts to where the wing is no longer adding major lift (say 30kts) that the prop pitch is important.
Regards, David Joyce, G-XSDJ

Sent from my iPad

On 11 Jan 2012, at 12:32, "John Wighton" <john(at)wighton.net> wrote:

Quote:


David,
Thanks for the reply/description. Having been an aeronautical engineer for 30 years l appreciate both the theoretical and practical analysis of a problem. Clearly you have a heap more experience in the practical sense, especially w.r.t. Europa flying.

I have at hand a bunch of tools (including Fluid-Dynamic Lift and Drag by Hoerner/Borst, CFD programs, etc) from which l would happily spend hours/days/weeks quantifying this discussion. But that will have to wait until l finish this pesky A380 work on my desk right now.

A rough calc ((at)50kt landing to standstill), along the lines of your suggestion, reveals a flat plate drag load of about 96 lbf for the fine (zero degrees in fact) pitched prop prop (4lbf for the feathered prop). This will reduce quickly with the square of the speed ((at)25 kts max load is approx 24 lbf). The proportion of total drag during the ground run will depend on a heap of stuff (tyre pressures, ground friction), etc.

So unbraked l think you have a point. With normal (or higher) braking l think the difference will be a lot less (as prop drag

--------
John Wighton
Europa XS trigear G-IPOD




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max8992



Joined: 28 Jul 2011
Posts: 142

PostPosted: Wed Jan 11, 2012 5:57 am    Post subject: VP prop, good idea? which one? Reply with quote

Hi there all,

I'm very impressed by the level of expertise available in this community,
many thanks to each and everyone. To put my stone on the edifice, I will add
that using a C/S prop (Airmaster on 912) give an additional comfort of
flight within perturbed windy weather, as the prop variation acts as a shock
absorber. Together with the very good profile of the wing make my flight
smooth, much better than some other comparable birds like Dynamics or
Lionceaux.
Max Cointe
F-PMLH TriGear Kit #560
912ULS Airmaster 400 hours
-----Message d'origine-----
De : owner-europa-list-server(at)matronics.com
[mailto:owner-europa-list-server(at)matronics.com] De la part de John Wighton
Envoyé : mercredi 11 janvier 2012 13:32
À : europa-list(at)matronics.com
Objet : Re: VP prop, good idea? which one?



David,
Thanks for the reply/description. Having been an aeronautical engineer for
30 years l appreciate both the theoretical and practical analysis of a
problem. Clearly you have a heap more experience in the practical sense,
especially w.r.t. Europa flying.

I have at hand a bunch of tools (including Fluid-Dynamic Lift and Drag by
Hoerner/Borst, CFD programs, etc) from which l would happily spend
hours/days/weeks quantifying this discussion. But that will have to wait
until l finish this pesky A380 work on my desk right now.

A rough calc ((at)50kt landing to standstill), along the lines of your
suggestion, reveals a flat plate drag load of about 96 lbf for the fine
(zero degrees in fact) pitched prop prop (4lbf for the feathered prop).
This will reduce quickly with the square of the speed ((at)25 kts max load is
approx 24 lbf). The proportion of total drag during the ground run will
depend on a heap of stuff (tyre pressures, ground friction), etc.

So unbraked l think you have a point. With normal (or higher) braking l
think the difference will be a lot less (as prop drag

--------
John Wighton
Europa XS trigear G-IPOD


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PostPosted: Wed Jan 11, 2012 7:03 am    Post subject: VP prop, good idea? which one? Reply with quote

Hi All

I have an AirMaster 332 with Warpdrive blades.  There are some considerations to take into account in a couple of areas.

I have found this hub to be very robust and its maintenance requirements are low.  You do need to consider the cost of repair. The cost of sending it internationally is a very high part of the repair bill and cycle time.

If you live in Europe, then Woodcomp is as local as it gets.

If you live in the US, then whirlwindaviation.com is local. 

I can say that Airmaster are responsive, and the service is probably as good as it gets for a one man show but for someone in the US this is a 6 week cycle time.

Of course you can be local but still offer poor service. Smile

The next considerations is performance.  From aerodynamic perspective the Warp drive blades are very bad. Martin is working on alternatives.

The blades on the Whirlwind were designed by Jack Norris with Rotax in mind and they are aerodynamically sound.

The has been good research and numbers published on the Woodcomp blades.

Lastly, the Whirlwind propeller is less than half the weight of an Airmaster.  For a 914 this is very important.

Cheers,  Paul
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PostPosted: Wed Jan 11, 2012 8:51 am    Post subject: VP prop, good idea? which one? Reply with quote

Hi Paul,

For info, for those in Europe, Europa Aircraft are the repair agents for Airmaster. They can carry out a limited range of repairs and will organise the return to Airmaster if necessary.

Regards

Brian Davies

From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Paul McAllister
Sent: 11 January 2012 15:00
To: europa-list(at)matronics.com
Subject: Re: Re: VP prop, good idea? which one?

Hi All

I have an AirMaster 332 with Warpdrive blades. There are some considerations to take into account in a couple of areas.

I have found this hub to be very robust and its maintenance requirements are low. You do need to consider the cost of repair. The cost of sending it internationally is a very high part of the repair bill and cycle time.

If you live in Europe, then Woodcomp is as local as it gets.

If you live in the US, then whirlwindaviation.com is local.

I can say that Airmaster are responsive, and the service is probably as good as it gets for a one man show but for someone in the US this is a 6 week cycle time.

Of course you can be local but still offer poor service. Smile

The next considerations is performance. From aerodynamic perspective the Warp drive blades are very bad. Martin is working on alternatives.

The blades on the Whirlwind were designed by Jack Norris with Rotax in mind and they are aerodynamically sound.

The has been good research and numbers published on the Woodcomp blades.

Lastly, the Whirlwind propeller is less than half the weight of an Airmaster. For a 914 this is very important.

Cheers, Paul
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paul.the.aviator(at)gmail
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PostPosted: Wed Jan 11, 2012 9:41 am    Post subject: VP prop, good idea? which one? Reply with quote

Hi Brian,

Thank for sharing the additional information.  Without diminishing your input up until now the work that local dealers have been able to perform has been limited and things like blade replacements has required a return to the factory.

With that said Martin has now made some changes to the hub that greatly simplify replacement of the blades, and this change can be retrofitted to existing hubs. I wouldn't be surprised if some of the local repair facilities get themselves set up with alignment jigs and dye check and static balance rigs to field replacement of blades.

Just as an FYI, I did purchase the adjustable back plates for my hub and I plan to fit them over the winter.  Martin has also identified two alternative blades for the 332 hub that I am assisting him with testing.

I don't expect to be able to report anything for a while as I have brought my airplane home for the winter to do those 101 small jobs that I always put off over the summer.

Cheers,  Paul

On Wed, Jan 11, 2012 at 10:48 AM, Brian Davies <brian.davies(at)clara.co.uk (brian.davies(at)clara.co.uk)> wrote:
[quote]
Hi Paul,
 
For info, for those in Europe, Europa Aircraft are the repair agents for Airmaster.  They can carry out a limited range of repairs and will organise the return to Airmaster if necessary.
 
Regards
 
Brian Davies


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