[Thumper]

Scare me time:

what might a suitable budget be to retrofit a constant speed prop onto a GA aeroplane?? I know there are a number of makes out there so wondered if anyone has trodden this path?

ty

[Rod1]

I upgraded my fixed pitch prop to a CS unit on my MCR about 10 years ago – cost about £3000 and some time. This is on a permit aircraft and the prop was for a Rotax 912ULS.

Rod1

[Shoestring Flyer]

I have been pricing CS props in the last month and I have been quoted £8k for an Airmaster CS Prop, £9.2K for a Duc CS Prop and £6k for a Woodcomp CS prop.
The above were for a Rotax 912uls engined aircraft.
Noting your previous interest in a Groppo Trail far be it from me to put you off but putting a CS/VP Prop on a draggy airframe like the Trail may not be in the benefit versus cost game all that great.

[carlmeek]

I should think it mostly depends on whether it's certified or LAA. If it's LAA then it's a cheap and simple mod plus propeller cost.

Two main types of prop are out there: electric and hydraulic.

My three blade MT hydraulic which fits a lycoming cost about 10 grand. It needs a governor too.

Electric ones need a control box and the prop.

[A le Ron]

The wonders of LAA land.
I've just replaced a Hartzell 2-blade constant speed prop on a C of A aircraft at just over £19K.

[cockney steve]

@Shoestring Flyer said

I have been pricing CS props in the last month and I have been quoted £8k for an Airmaster CS Prop, £9.2K for a Duc CS Prop and £6k for a Woodcomp CS prop.

Even at those (relatively) low prices, one has to query the payback time. £6K buys an awful lot of fuel to make up the difference in burn between a C/s and a fixed-pitch...also you have to factor the not-inconsiderable extra maintenance cost of the C/s prop.

[carlmeek]

Fuel efficiency isn't really the reason to buy one. The real reason is decreased take off roll and improved cruise speed.

[Marvin]

One thing to consider is any change to the CofG as a result in the extra weight on the nose.

This may impact some of the LAA types and how they have been constructed.

If you have to sort any other changes i.e. Move batter rearward etc. Then additional cost and time.

[Shoestring Flyer]

Yes you are right the additional weight and CofG can be an issue on an LAA machine and of course you need to convince the LAA of the suitability and it therefore requires MOD approval. Of the three I am interested in the Airmaster is the heaviest being 11.5kg. the Woodcomp weighs 9.5kg and the DUC is the lightest at 7.5kg.
The Airmaster is the best maintenance wise because it can be maintained in the field as it were, the Woodcomp requires 7yearly dealer/factory checks and the DUC needs to go back to the factory in Lyon every 5years at a labour cost of 850Euros +parts +carriage+vat.
So quite a lot to think about .....

[Flyin'Dutch']

It all really depends on the aeroplane and engine you are looking at.

CofA - forget it, just sell up and buy something with a CS prop if that is what you want. The paperwork and engineering hassle is not worth the bother. Some CS equipped aeroplanes have been retrofitted with a fixed pitch prop - that is both from a technical and paperwork point much easier.

LAA - thread carefully as there will be costs and paperwork stuff involved.

For anything going slower than 120kts and or less than 200 hp it is unlikely to give a performance benefit.

If your current stead is lacking in cruise speed or take off performance consider getting a different pitch prop.

Or get a different aeroplane.

[Shoestring Flyer]

In a reasonably slick airframe behind a Rotax 912uls there are big gains to be had from a VP or CS prop over a ground adjustable prop. The main gain is always in the take-off roll and climb, cruise speed less so.

[carlmeek]

Indeed. My Tecnam sierra operated out of under 300 metres and cruised at 130kts. Far in excess of non wobbly prop sierras.

[cockney steve]

@Marvin said

Move batter rearward etc. Then additional cost and time.

Ah ,so -you going frying ?

[Thumper]

Fabulous answers from everyone.

Many thanks for this.

OP re wobbly prop on a Groppo - wouldn't bother on an aeroplane like that due to its already small payload (at least on the mk1)

[GolfHotel]

Fuel efficiency isn't really the reason to buy one. The real reason is decreased take off roll and improved cruise speed.

Agree entirely with the above rational.

However I do find surprising good fuel consumption with my 7 with a CS prop.

But the REAL reason. FUN FUN FUN. Take off and climb are spectacular!
Landings are a bit better but I still like it if no one is watching.