VW engines what prop

[Go Vert]

I have always read that one cannot use a comb prop on a VW engine, but I would like to know what the reason is if anyone has an explination ?

[justin.schoeman]

You can use a composite prop, but not direct drive. The torque reversals on a VW are too severe, and composite props tend to break at the root.

The crank doesn't rotate at the same speed the whole time - as one piston is approaching TDC compression, it slows down, and once it passes TDC, it speeds up again. All engines have this to a greater or lesser extent, but it is worst on small 4 strokes (I doubt you will ever see a direct drive BMW conversion - and most of the sucessful ones use a clutch to disconnect prop drive at low RPM).

4 cylinder 4 strokes are better, but not great. Many composite prop manufacturers will not approve their props to run on a Jab 2200 for this very reason (but they will allow it on a Jab 3300).

The strength of the crank is also an issue - rigid props absorb less of the torque pulses and result in higher stress on the crank. Wood is actually remarkably flexible, and absorbs the toque pulses quite nicely.

[Go Vert]

Thanks Justin

now next question is what type of prop works best on a type 1 direct drive if you were looking to hit cruise/static more or less middle 50/50 would you suggest a single blade biggish prop like the P prop or a 3 bladed prop?

[Go Vert]

oh sorry aircraft is high wing medium drag ( similar to BB ) empty weight aprox 240kg

[justin.schoeman]

Thanks Justin

now next question is what type of prop works best on a type 1 direct drive if you were looking to hit cruise/static more or less middle 50/50 would you suggest a single blade biggish prop like the P prop or a 3 bladed prop?

Speak to Pieter de Necker (P-Prop) - he will give you the best advice. I have never seen anything but wood and wood/composite 2 blade props direct drive. Length is tricky. Probably around 64". Pitch depends on engine capacity...

[Jean Crous]

Go Vert, the Revmaster series can use composite props Ivo, and Warp-drive because of the 4340 chromolly cranck and the big no 4 main bearing at the prop-hub end. However from personal experience with said engine a P-prop works best , believe me. The Revmaster 2332cc uses a 64x38 prop with a nice wide cord to the blades This works VERY well in the Bushbaby.
Regards
Jean Crous

[justin.schoeman]

Go Vert, the Revmaster series can use composite props Ivo, and Warp-drive because of the 4340 chromolly cranck and the big no 4 main bearing at the prop-hub end...

Yup - the Revmaster engine can handle the prop, but if you tell Ivo that you want a prop for a VW (or even a Jab 2200), he will refuse to sell one to you... Haven't spoken to any of the other composite prop manufacturers, but Ivo said that their prop will break.

[Boet]

VW engines = 2 blade wood prop. Anything else = TROUBLE !

[justin.schoeman]

VW engines = 2 blade wood prop. Anything else = TROUBLE !

Wat nou Boet? Ek dog jy sou die stuk tussen die '=' tekens uit los?

[Jean Crous]

Ja VW engines,BUT......to the uninformed, a Revmaster is NOT a VW engine , ONLY the cranck-case is and this is re-machined to such an extent that it no longer can qualify as a VW case The cranck is 4340 chromolly (harder than a Lycoming cranck) conrods are also H-beam 4340 chromolly, cylinder heads are much different on comparison to the aftermarket VW ones, and so my friends the list goes on "ad nauseum"
Revmaster can take wood/composite/metal props....even an oil -controlled constant speed prop

[KFA]

Wat weeg hulle deesdae, fully installed?

[Go Vert]

Ja VW engines,BUT......to the uninformed, a Revmaster is NOT a VW engine , ONLY the cranck-case is and this is re-machined to such an extent that it no longer can qualify as a VW case The cranck is 4340 chromolly (harder than a Lycoming cranck) conrods are also H-beam 4340 chromolly, cylinder heads are much different on comparison to the aftermarket VW ones, and so my friends the list goes on "ad nauseum"
Revmaster can take wood/composite/metal props....even an oil -controlled constant speed prop

Ja nee dis n dorner se nice machintjie maar is nou F>cken duur vir my poject, ek sal die revmaster wannabe moet laat werk

[Go Vert]

Wat weeg hulle deesdae, fully installed?

Toe ek en Jean anderdag gepraat het hy my gese maar het nou vergeet maar vasie baaie

[Jean Crous]

Hi KFA en vriende, sonder exhaust maar verder met alles weeg die Revmaster 78Kg, oil cooler , carb- and- all ek se

[krjockey]

Revmaster can take wood/composite/metal props....even an oil -controlled constant speed prop

Revmaster had lots of problems with that CSU metal prop setup and canned it completely. If its direct drive stick to a wooden prop.