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heavy hauler with VW

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Posted

All recently acquired a HH project with a VW mounted already. Still quite a bit of construction to complete. My question is about reduction drives for this configuration. I see little on this site about use of VWs with Avid or Kit Fox. Plan on using 3 blade warp drive.  

Any assistance appreciated. 

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Posted

The VW is a heavy engine if you add a reduction what will that do to your W/B? Which VW do you have?

 

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Posted (edited)

There's a reason there's no information out there on it. The power to weight ratio is just not there and weight and balance becomes a serious issue. I'd go with a soob long before a VW because at least you can crank out some HP with it.  If you are wanting to go 4-stroke do the 16" stretch and put a 912 on it. If I was in your shoes and building a complete project that's the route I would go. An auto conversion is a mechanics motor. A 912 is a consumers engine. You need to ask yourself If you want to spend all all your time tinkering and still have a plane that a 582 powered Avid will fly circles around or if you want something that is turn key and will make you giggle every time you push the power in.

Edited by C5Engineer
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Posted

I'll second Joey as to why there's no information.  VW engines don't work well in these planes. Redrive or not.  They are low on power, low on reliability and high on weight.  They are also not supported by any kit maker for engine mounts or cowlings.

I did a ton of research before getting into these planes.  I was intending on a VW powered Kitfox. The more research I did the worse the outlook was.  They just don't match the needs of this class of airplane.  There are a couple of airframes designed around the VW engine.  They work reasonably well, but the Avid/Kitfox is definitely not one of them. 

I could list several people I personally know that have tried VW engines, spent thousands of dollars on engine mounts, props, redrives, and many other things.  The ones that are still flying have all finally gone to Rotax 912 engines. 

 

My my advise to you is to cut your losses now before you are too financially buried and go 912.  You will be money far ahead in the end. 

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Posted

I was just talking with a guy yesterday that had a Kitfox 4 that came with a VW when he got it.  It really wasn't a very good plane with the VW and hardly got flown.  He found a 912 and put that on.  Lost 50 lbs and gained tons of performance.  He likes the Kitfox now.  He also mentioned that you must use a wood prop on them because of the power pulses from the engine.  Broken crankshafts if you don't use a wood prop.   I'm sure that's true with direct drive, maybe less so with a redrive.   Jim Chuk

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Posted (edited)

I have heard that without the big (2150?) VW and a redrive, you don't have the torque power to pull a prop big enough.  There is a VW redrive on ebay for $700, and you can use a 3-blade prop with it.   Of course there is the weight problem.  You can get a Soob with redrive for probably less than the $2500 listed on ebay, but you need to extend leading edges, or better, extend fuselage too.

Money fixes everything - You just have to decide how much, and for what...

EDMO

Edited by EDMO
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Posted (edited)

I have flown a direct drive 2180cc vw powered kitfox 4-1200.  the biggest prop you can swing with the rpm of that config is 62 inches which equates to piss poor performance.  the best solo climb i saw was about 600 fpm, dual we were lucky to see 200 fpm. not a performer whatsoever. 

Edited by thebriman

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Posted

plus the heavy engine made it impossible to use flaps for landing as it didnt have enough elevator.  i wouldnt give up my seat in the electric chair to have a vw on a fox or avid.

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Posted

I can't give any first hand experience because I've never flown an Avid of KF with a VW, so take this for what it's worth. I talked to a KF IV owner that had a VW with the Valley Engineering Redrive. He had a 3 blade IVO ground adjustable. He was very happy with the combination. He said it did take him a while to get the cooling figured out. He also had some weight bolted under his tail spring. Not sure how much. Maybe if I make it back that way, I'll see if I can get a ride to see what performance is like. Just another (limited) data point.

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Posted

You talking about an Oil cooler?  I checked a lot into this also, another one was" Big Twin" air cooled, in a V twin two cylinder configuration, much like an air cooled Wisc. Motor. Same conclusions for me, not enough horses for the weight penalties. 

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Posted

Do you happen to know what CC the engine is that is one your project? I know it's a bit off topic but I'm building a Sonerai and I'm looking for a VW engine. I also have a Subaru complete with Redrive that I might be willing to trade. If you are interested message me. 

Other than that, I agree that this airframe is not a good option for the VW power. Too draggy and slow. It works well in other applications. I have over 200 hours behind the VW in my Teenie Two and love it but the plane only weighs 370 pounds and is a very clean aircraft as far as drag goes. I also have quite a few hours behind the Subaru. Very nice smooth running machines with the redrives. It takes the harmonics out of the engine and just purrs smoothly along. Every engine has something it would work on well. The Avid and Kitfox just aren't good with the VW.

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Posted

Kenneth,   I think the redrive makes all the difference in how the VW performs - Larger prop with more torque - but adds weight.

EDMO

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Posted

Kenneth,   I think the redrive makes all the difference in how the VW performs - Larger prop with more torque - but adds weight.

EDMO

I'm sure that's true but my VW is direct drive. With my custom designed prop (my own design and build), I get really good performance with it. I still wouldn't fly it on an Avid though, just too heavy. I fly at a gross weight that is less than most empty Avid/Kitfox.

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Posted

Kenneth,   I think the redrive makes all the difference in how the VW performs - Larger prop with more torque - but adds weight.

EDMO

...yet still doesn't help the airspeed to power output ratio.  Still making it impossible to cool. 

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Posted (edited)

The Avid Fox with the VW mentioned at the top of this post has the redrive, and we are waiting on some performance figures for it.  I guess the weight is near the Soob with redrive weight, but air-cooled.  EDMO

The Soob was based on the same Boxer engine as the Contisaurus, Lycosaurus, VW and Porsche, but shorter stroke, newer engineering, and liquid-cooled.   EDMO

Edited by EDMO

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