Kambah Karatoo

[Methusala]

Just want to say that today I split the mold we took off the plug that we have laboured long and hard to create. It came off clean with few voids and with luck should be ready to take a couple of finished cowls from next weekend.

 

We were forced into this because the Subaru EA 81 was much too heavy and didnt produce the expected power. Will fit a rebuilt Revmaster of almost 2.2l saving about 40kg. Any other karatoo's out there? Don

 

 

[BigPete]

Don - can you tell me more about the Revmaster motor?

 

regards

 

 

[Methusala]

VW based Revmaster 2100D

 

Chris, the Subaru was mated to a Rotax C type box- 2.58:1 ratio and a 68"(?) 3 bladed Warp Drive. Without oil or coolant it weighed 115kg. The Revmaster conversion with 2 bladed 55" wooden prop weighs 75 and produces 75 hp@ 3600 rpm. The EA81 was fitted with a modified cam by Wade. Max rpm acheived (static) was c5500. At 430 kg weight, one up, it climbed at 500fpm @ 60 Kt.

 

I never dyno'd it but that doesn't seem like 90hp. But the main point was that it was probably nose heavy even with some 8kg lead ballast at tail wheel. Our plane is an A model, not the C model as sold by Amax. The absence of as much mass as can be pruned will do nothing but improve this delightful 'modern Piper Cub'.

 

I can say that in 20 hrs of test flying I found it to be a viceless u/l and hope to have it in the air again by the new year. Don.

 

 

[vk3auu]

You probably won't get startling performance out of it with the Revmaster either.

 

David

 

 

[eastmeg2]

Don,

 

I notice you've list Currandooley as your airstrip what's the status of that strip now? We thought it'd been closed due to a combination of wind erosion and the passing on of ownership from one generation to the next.

 

We used to drop in there from time to time in our trikes.

 

Rgds,

 

Glen

 

 

[vk3auu]

I have a friend in the States who flys a Zenair CH701, quite an old one. In the beginning he has a VW derivative, I forget which one, but he has plenty of money so it was undoubtedly a good one. His plane had all the goodies imaginable so was quite heavy and he never got to fly it two up. Incidentally, he also played around with all sorts of propellors of various diameters. The problem seems to be that the cowl is just a tad too big so that if you have a small prop, the engine develops the revs, but the prop is inefficient. If you have a larger prop, the engine doesn't develop the power even though the prop is more efficient.

 

One day he ran into a heap of rubble when he landed short so he took the VW out. His ultimate aim was to put in a Subaru, but while it was getting prepared, he put in a Rotax 503. Because it was a fair bit lighter than the VW, he had to put about 8 pounds of lead in the front to preserve the C of G. Guess what? The aircraft flew much better with the 503 than it did with the VW.

 

Not quite end of story.

 

At about this time last year I had a chance to fly a Subaru powered Zenair CH701, similar to mine. Because it was so heavy it didn't want to lift off until I got to over 50 knots. Mine with a 80 hp 912UL can lift off at just over 35 knots in the same configuration. I don't know how my friend's '701 performs with the Soob, but I suspect its pretty ordinary.

 

Most of the VW figures I have seen quote fuel consumptions of around 12 litres per hour. This equates to around 40 HP which might be OK for Corby Starlets, but is probably a bit on the light side for a Karatoo. I supect that a Jabiru engine would also have the same problem as a VW in front of a cowl the size of a Karatoo, whereas the 912 has a gearbox, so you can put a decent size prop in front to it.

 

I had a good look at the Karatoo about 15 years ago, but at that time, there were no suitable 4 stroke engines available. Nice aeroplane though. Andy Shea down at Yarram has a Karaone. First flight was with a half VW. Not good, rate of climb very slow, looked for gap in hedge about half mile upwind. Now has 1600 Jabiru, much better.

 

Happy flying,

 

David

 

 

[Methusala]

VW Derivatives

 

Dear David et al,

 

I don't expect "sparkling performance" out of the Karatoo. As you can see I have flown a Volksplane since 1995. I am quite familiar with VW's,

 

 

 

 

 

 

both R'master & Aeropower. I expect similar performance to Skyfox with Aeropower( altho the Revmaster has 94mmx78mm stroke giving from memory around 2160cc, a bit larger than Aeropower). I have experimented with props and

 

currently get 3450rpm at takeoff with the Aeropower and cruise at 3050rpm- 60kts burning around 18l/hr including climb. I operate from 2450ft and use about 250m to get airbourne, climb 350fpm in a heavy, draggy VP2. If your friend was only burning 12l/hr he is either prop limiting rpm or choosing too low an operating

 

engine speed. It is a common misconception that one mustn't run a VW at high

 

rpm. Tell that to Stan Pobjoy who has beaten all comers to be Aust hill climb champ in a 1916cc that in some corners he holds to 8000rpm ( no bull, no tricky bits, he doesn't even rebuild the engine from one season to the next).

 

Ahem... back to aviation. My aeropower was rebuilt 6 yrs ago by Mike Muninger, a Bavarian gentleman, after doing 450 hrs in a Lightwing. I have flown 320hrs since with NO problems. Finally, I have adapted Bosch fuel inj. hardware driven by Haltech f9 computer, and have had no probs( and no carb. ice) over 500hrs operation. I'm ready to continue this discussion, but you see, I'm not speaking as a dreamer. I've been there and done it, regards, Don.

 

 

[Methusala]

Curandooley airstrip

 

Just a "short note". Curandooley is owned by the Osbourne family. In their extreme generosity they allow a restricted, small no. of us access. It is private property and must be respected as such. We endeavour to maintain a low profile

 

especially regarding noise. That said, if you are passing and spot one of us at the feild, by all means drop in. Keep the circuit tight the strip is alright but be aware of possible ruts stemming from the deer buck's habits.Don.

 

 

[eastmeg2]

Thanks Don,

 

The main reason we ever dropped in to Currandooley in the past was to socialise with anyone we might spot on the ground there if we happen to fly that way. We've previously been briefed to keep any circuits to the couthern side and trikes tend to fly tight circuits anyway.

 

Have not overflown that strip for probably 6 months now.

 

Maybe we'll see you at the Goulburn Airport BBQ on Saturday . . .

 

Rgds,

 

Glen

 

 

[vk3auu]

Methusela, you obviously know more about VW engines than the average Joe. I don't know what revs my friend was getting or what fuel consumption. I suspect that his major problem was one of gross weight more than anything else. He was a retired Judge, so probably not that mechanically adept.

 

I met a bloke over in England a few years ago, can't remember his name, might have been Mike Smith. He was one of the heads in the PFA. He had a nice little single seater aerobatic aeroplane with a symmetrical wing that had a fuel injected VW that went pretty well.

 

There were a couple of blokes at Narromine two years ago that had a VW with a 2 to 1 gearbox. I haven't seen anyone using that version. I know it was supposed to rev to 4000. The formula V racing cars seem to be able to extract a bit of grunt without destroying them. I would think that longevity depends much on adequate lubrication and cooling as well as getting the mixture right.

 

A lot of flyers seem to have a fixation about getting fuel consumption down by leaning the mixture too much, but what they save in fuel is made up for in mechanical repairs. I wonder if you have tried piezo injectors, like they use in the modern diesels. I drive a 400000 Km VB Commodore, that's about where my hands on experience is at. My wife's 2 litre Lancer goes to the servo when it needs anything.

 

I will be interested to see how the Karatoo goes.

 

David

 

 

[Methusala]

VW engines (again)

 

Dear all,

 

My point in this discussion is only to say that our form of flying should remain as diverse, accessable and affordable as can be. I investigated Jabiru at

 

one stage, but having had good results from VW's I stuck with that. I am in favor of as much diversity as possible and really am impressed by the technically advanced models available. But I think that if entry costs don't stay low then our recreational flying will go the way of GA rec flying. Now, Thruster anyone? DON.

 

 

[Guest rocketman]

Interesting to read of your Karatoo efforts. I recently took over the rights for the Karatoo from AMAX Engineering. You say it's an "A" model. Did you get a construction manual with the plans / kit? I recently had a enquiry for a builders manual for an "A" model from South Africa. The manual I inherited is pretty sparse in detail and is more in line withthe B model. The plans we have though are pretty detailed. Even have the metal wing variant but it will be a while before it flys.

 

So what is the engine of choice now?