vw engine

[Guest micgrace]

Hi guys, just thought I'd add something on VW.

 

Looks like my engine of choice (cost basis) for my 95.10 design will be a direct drive VW. Advantages. Cheap. Easily converted. Ready parts availability. Range of possible power outputs depending on capacity. Easily obtained.

 

Downside. Continuous power rating could be better. 50hp for 1600cc. 60hp for 1800 and so on (these being the only real cheap capacities the rest require a crankshaft/piston change) All up weight could be better being 72kg But electric start/alternator/direct fire ignition included.

 

But also available are liquid cooled dual ignition cylinder heads combined with stroker crank, rear drive setup 100hp (expensive)

 

Cost of me (please don't ask me to do one for you, I won't ) doing a complete conversion is in the vicinity of $2000 (I build and modify engine to suit includes parts for the conversion)

 

Even less with good scrounging ability. For those interested go to great plains aircraft web site.

 

For those on an extremely tight budget (like me) worth considering.

 

Disclaimer: I am a qualified mechanic/dip. engineering/part way through BSc Degreewith much engine experience DO NOT attempt this if you don't have the necessary skills. You have been warned. Believe me it takes only a very small change to have catastrophic results on an engine and without formal training you will not know what that is.

 

Micgrace:)

 

 

[Guest danda]

I was just wondering about the 1800 vw engine for the Diamond it has a 503 at the moment with 20kg of lead siting on the top to counter balance my rather robust size I’m not a big fan of the 2 stroke and not having a lot of money the vw may be the way to go. Approximately how much would it cost to setup a 1800.

 

Don

 

 

[Guest micgrace]

Hi there.

 

I thinkif you chucked the rotax and lead, you may need to add akilo or so in the tail. I think a basic VW conversion is around 73kg versus some 47kg for the rotax, close , but not that close. plus mounts are nothing like the rotax, the engine will probably sit further foward if the rotax is fairly close to the firewall. Be warned on CG

 

There is no 1800 VW engine (type 1 (beatle)that is used in aircraft DO NOT GET ANY OTHER TYPE YOU WILL NOT FIND ANYTHING FOR IT except some limited parts for type 4 (kombi))

 

A 1600 dual port has to be converted. This consists of new barrels and pistons. machine work to the crankcase. Plus a rebalance. It will of course up the compression, which is then "cured" by shimming the barrels. A better solution is to use custom pistons then you don't have to create custom length pushrods. You can knock it up to 2400cc if you want but that costs$$$$

 

Plus I would recommend the use of the great plains force one prop adaptor if doing direct drive. This contains a bearing setup to takeup thrust load plus increases the effective diameter of the crank snout. BUT invovles a fair amount of machining work. Strictly wood prop only. a 58" x 42" fine for 60hptheoretical speed to 120knots.

 

There are other internal mods, mainly oil supply that are used on oil passages, lifters, rocker arms, plus oil pump size change, cooler, remote oil filter (VW don't use one in the beetle)

 

If doing a PRSU unit, more hp plus a near doulbling in thrust. But for the dollar challenged, direct drive will have to do

 

Other changes well worth considering are twin spark water cooled heads plus a full twin spark conversion. But very exspensive. Include a rear drive gearbox plus the lot. But then again, after all that might just as well get a dedicated engine locally (jab, arm and leg)

 

I'm not a great fan of the standard carby setup at all. I tend to be in favour of fuel injection. I reckon carbies came with Noahs ark.

 

This is not at all that hard, although very careful attention to detail is required.

 

Lift pump from main tank (dual of everything if you must) To surge tank on firewallMUST USE, may incorporate in main tank. To EFI pump underneath to injector rail to engine. Everything will have to be handmade unfortunately.

 

With a simple fuel only EFI computer, electronic dizzy, around 10% power increase, fuel consumption decrease. Temp compensation, altitude compensation (direct measure of manifold pressure) Throttle opening enrichment for acceleration. Automatic fuel enrichment if desired based on CHT/O2 levels (no Avgas).

 

PLUS (with the correct system complete inflight control of all engine parameters. Complete with more info than you could ever imagine.

 

PLUS no more silly carb heat.

 

PLUS a complete log of all flight paremeters which you can then download and printout to make adjustments.

 

With a more sophisticated unit, direct fire (4 coils) on all cylinders. Automatic adjustment of ignition timing to suit all operating paremeters. Plus if using detonation sensors the ability for automatic resetting of timing as well to suit available fuels.

 

Unfortunately (or fortunately)full EFI works so well problems that cause a carby setup to stop working generally don't have much of an effect on EFI. If the owner neglects maintenence, the first thing they become aware of a problem is a complete stoppage.

 

Which is why no car manufacturer sells carby vehicles anymore, although their motive is self interest (pollution laws), not performance advantages.

 

As for myself, I nearly forgot about this versatile engine and was just going to get a 2 stroke rotax, nearly the only built engine I can afford.

 

Sorry to say, I just don't trust them after having an engine failure in one for no known cause. All I could think of was a whisker across the plug, more common than realised. Gimme a 4 stroke.

 

The horsepower rating of late has changed tack to unbelieveable figures that do not compute. The current trick is to use the max power as the usual power, plus with nil accessories attached (DIN)

 

There is a mob on Bribie Island Queensland making 100 hp (take off power I presume) injected VW engines with reduction drive. They call themselves VW engine centre

 

Micgrace

 

Disclaimer: The information contained is of a highly experimental nature. Anybody using the information does so at their own risk. You are strongly advised to use a qualified person experienced in aircraft engine construction. micgrace

 

 

[Student Pilot]

There's making power and usefull power. With a direct drive the prop diameter is the problem, doesn't matter what the power rating is you won't get much more than 60 HP and lots more noise. That's where a geared Rotax 502 will develop more thrust than a VW.

 

 

[Guest micgrace]

hi

 

Rotax 503 or 582 (must be a typo)

 

582 packs quite a punch I must say for what it is The reduction drive certainly provides mechanical advantage to produce torque (thrust) to overcome the main 2 stroke disadvantage stuff all torque at lower rpm.

 

The aim of the outline was to inform on some things that can be done on a miniscule budget.

 

Of course there are some limitations in using a direct drive engine. The main one concerns prop choice. Smaller diameter than might otherwise be the case i.e. need to run engine to max (direct drive of 3,300 rpm, same as prop probably around 100 - 120 lb thrust)

 

But spend the money on a 2 : 1 Prsu hp and hence torque and thrust rise dramatically, then able to run prop at much more efficient 2800 - 3000rpm Effectively more than doubling it.

 

BUT these things are expensive and add considerable weight. So, like all things in aviation, a compromise. Also higher crankshaft speed = wear so you can't have it both ways.

 

If I was to go for shear hp (apart from turbine) turbo injected PRSU equipped wankel rotary for 300+ hp 3:1 reduction

 

Several other ways to increase (hp) thrust in a VW or any enginewithout resorting to a PRSU are a massive increase in capacity to 2200 or the use of a small turbo. The small turbo (to match rpm range) being the better of the solutions. (engineering it aside)

 

This correctly designed on, say, a 1600 could effectively give you 100 take off hp (5 mins) and some 240 lb thrust.

 

Or a 2200cc VW would be rated at 80 hp @ 3300

 

Using a quick rule of thumb, increase pitch from some 42" to .7 x 80 (more likely output) for 56" pitch. Of course you can't really change the prop diameter (larger)as the tip speed won't be very far off supersonic. Although with an excellent prop design may be able to sneak in a few extra rpm for takeoff and faster climb (reduce the pitch 2").

 

The Jab is naturally aspirated direct drive almost VW like. Interestingly the capacity is 2200, 80 hp (was originally 1600) The solution used there is large capacity, weight reduction techniques. Quite a good solution to this problem where internal combustion engines operate to a different rpm than propeller efficiency.

 

The idea of any engine is try to match the expected performance parameters of the aircraft. Like everthing else a total compromise. That's probably why no design type dominates aviation.

 

In due course I will add some photos and engine/injection construction outlines for those interested in something just a little different. Plus photos of the design when I start building itwhere it will be going in.

 

I'm moving house very shortly. Bought one with a shed big enough to do something in (8m x 10m) Was very hard finding a house with a decent shed in Brisbane. As for Sydney or Melbourne? I'd hate to guess.

 

Micgrace micgrace

 

 

[Student Pilot]

With the 502 I was thinking of an Airtractor, 503 is the Rotax.

 

Years ago when things first kicked off in the ultralight side of things, the old twin Robin with a belt reduction was getting very close to 240lbs thrust at sea level. That was measured installed in the Aircraft.

 

For a VW to develop that sort of power you would be runnning 5000 revs+? with a reduction?

 

 

[Guest micgrace]

Hi

 

Thanks for pointing that out on thrust figures above I confused torqure figures with them, they are closely related. The correct figures (theoretical) taking thrust = hp x prop diameter(') x 2/3 x 6.5

 

gives some 420 lbs thrust on a 58" , 60 hp (1600cc) (max diameter is 62") but this is only an approximation. This being for a 2 blade wood.

 

But there is a difference in favour of the rotax 582 for the same hp of some 20% mainly because a bigger diameter prop can be run before hitting supersonic.

 

A VW can be run for takeoff at max 5500 using a2 : 1 reduction gives some 2,750 rpm (very ideal prop speed) and some80 takeoff power but a vast increase in thrust, due to much larger prop., say 72" and freedom from being restricted to two blade wood props as well.

 

At the end of the day this idea was to use a simple engine without invovling much cost. But for superior results from an internal combustion engine definitely gearing down is the way to go. If you can afford it.

 

I will do some static thrust tests when completed.

 

Micgrace

 

 

[Guest micgrace]

Hi

 

I did some further calculations and research. A 60 hp direct drive engine limited to 3,300 rpm takeoff in the 95.10 catergory gives using a 62" x 42" prop (tip speed mach 0.75 max) gives 455lb thrust.

 

Which gives (660lb MTOW) thrust/weight ratio 0.69. Note that a figure greater than one it is possible to go vertical.

 

Using metric acceleration comes out at 6.7 m/s/s you would be looking at a very short takeoff of about 3 secs. To allow for ineffiecienes double it 6 secs.

 

I consider this to be ideal for the application I will be putting it to. Lets say I use it in the 95.55 category MTOW thrust weight becomes 0.38 acceleration becomes 3.7m/s/s this becomes unacceptable (crash at end andbarely climb a distinct possibility)

 

Micgrace

 

 

[Guest RonDunn]

Hi all.

 

Am rebuilding a VP1 (ugly duck!) and will be looking at/for a basic direct drive 1600 VW to power it. If I build, ignition will be original distributor and carby will be a 36/40 mm bing. If I cannoy buy a straight shaft prop hub for it will look at having one turned up from drawings and face plate drilled to suit the 1600 Jabiru prop. Have one handy and should be easier to obtain in event of damage.

 

Hauled the Jabiru with 2 up on a warm day OK. Any replies on this?

 

Regards

 

Ron

 

 

[Guest micgrace]

Hi

 

If doing a VW just go to Great Plains A/C site for parts. You will be able to get all manner of bits for the VW. www.greatplainsas.com

 

Micgrace:)

 

 

[Student Pilot]

Hi I did some further calculations and research. A 60 hp direct drive engine limited to 3,300 rpm takeoff in the 95.10 catergory gives using a 62" x 42" prop (tip speed mach 0.75 max) gives 455lb thrust.

 

Micgrace

So what thrust does a 60HP VW ACTUALLY develop measured on the tail of the Aircraft? I'd guess at around 220lb? 455lb sounds a lot.

 

 

[Guest micgrace]

Hi

 

So what thrust does a 60HP VW ACTUALLY develop measured on the tail of the Aircraft? I'd guess at around 220lb? 455lb sounds a lot.

 

That is theoretical calculation. Real world may be 50 -75% of that depending on airframe obstructions, propeller design etc.

 

Micgrace