Trying to decide which one to build

[diesel]

Rotax is of course geared. Actual piston speed of the engines is an interesting way to look at it.

 

Like schoolboys , some short strokes etc.Same end result sort of.

 

Chas

 

 

[facthunter]

Short stroke hasn't much leverage (torque). There is a concept of "limiting" piston speed, as well as actual slip/contact surface) speed in bearings (plain) This is due to limits in conventional lubrication products as much as anything. Nev

 

 

[diesel]

Short stroke hasn't much leverage (torque). Nev if you pull out your calculator you will probably find piston speed is the same.

 

Stroke x rpm.

 

Chas

[Jaba-who]

Unfortunately you cant fly a home built RA registered aircraft into CTR, but the same aircraft with VH reg can. Go figure. A friend had this issue and had to convert to VH after registering with RA.

This is completely untrue. You can, my flying mate does it based ( in his RAAus registered home built J230) numerous occasions and I have flown both in his aircraft with him and in company in my own VH registered Jabiru ( home built). His was originally based at Cairns International Airport and has only just recently moved it to Atherton. He has a completely home built jabiru.

 

What makes it legal to fly in CTA (even an RAAus one) is that the aircraft has a radio and a transponder and HE has a PPL ( as well as his RAAus pilot certificate).

 

The same applies to the other statement about rotax powered aircraft. There were some BASED in Cairns over the last twenty years that I have been flying out of Cairns.

 

 

[KRviator]

First : Rotax service, 912 ULS, 100 hr intervals on ULP, 3 litres of oil per service, automotive style spark plugs, engine performs best on ULP, smooth, quite, operation, slow prop speed (thanks to a g.box) with potential for enhanced efficiency, depending on prop selection. My Zephyr cruises at 100 knots, under 13 l/hr, one pilot, climb prop. I can do lazy orbits all day, around my home patch, at under 8 l/h. Yes I can go faster but I enjoy flying and 120 knots burning about 17-18 l/hr doesn't do it for me. There are other more sophisticated (usually more expensive - ATEC Fayeta, Pipistral Virus SW, Robin Austin/Sonerai) Rotax aircraft that are even more efficient (130-145 + knot cruise). I believe Rotax & Lyc both have 2000 hr TBO's so no advantage here.

The O-340 in my RV-9 does exactly the same. Automotive plugs, dual electronic ignition, burns Mogas, and if I want to dawdle, the fuel flow is down around the 15LPH mark at 120KTAS, probably lower, but I don't fly that slow that often. 145KTAS at 8,000 burning 24.2LPH of Mogas is what I plan, and achieve regularly. And that will probably increase to 150KTAS when I tidy up a few draggy items. I was able to put it in the air for well under 100K using the QB kits, a brand-new engine and Dynon package.

 

Try comparing (unfairly) your RV with one of the other aircraft I have mentioned. RV's and the like, don't win NASA-CAFE or similar competitions. Ask yourself WHY?

The current holder of the CAFE TriAviathon is.....A (very tidy,admittedly) RV-4...250SMPH top speed, 44SMPH stall, and a RoC of 3300FPM.

[Tasmag]

It is interesting that an experimental RA build can fly in CTR, a friend was advised that he could not fly into C or D with his home-built Jab under RA reg, even though he had a full PPL. I will ask if he had a reference for the restriction, or whether it was simply word of mouth.

 

 

[bexrbetter]

I was able to put it in the air for well under 100K

Wow, you cheapskate you, I can see half the forum running out to get the same now you've let that secret out.

 

 

[SDQDI]

It is interesting that an experimental RA build can fly in CTR, a friend was advised that he could not fly into C or D with his home-built Jab under RA reg, even though he had a full PPL. I will ask if he had a reference for the restriction, or whether it was simply word of mouth.

This is some good old 95:10 rules.

 

Look at 6.1 © (iii) which refers also to 7.4.

 

Basically from my quick look it basically says CTA is ok if you meet the same requirements for flight over 5000ft (if it is equipped with serviceable radiotelephone equipment and the pilot is qualified to use it)

 

Civil Aviation Order 95.10 Instrument 2014

 

 

[RetiredRacer]

Wow, you cheapskate you, I can see half the forum running out to get the same now you've let that secret out.

Hey bex, I'm trying to work out if your tongue in cheek statment was, you don't believe that's all it cost or you think it cost too much.???

 

I got our 9a in the air for $86k but the engine was a rebuild and there was no labour charge. The Vans kit was a quickbuild and I never paid for any labour as I did it all myself.

 

 

[bexrbetter]

you think it cost too much.???

Just a bit, but I was amused by the "well under" bit.

 

 

[Jaba-who]

Getting back to the original question about what to build.

 

I had a thought.

 

You seem to be happy with the idea of the jabiru airframe. It seems to be the engine that's the concern. You also seem to be keen on building it yourself.

 

The reality is it will take quite some time to do the build. I took 1400 hours (admittedly only 13 months - but I had a deadline to meet and that was working almost every day late into the night after I got home from work and pretty much worked on it every weekend) most people take years -some many.

 

Assume several years.

 

You can buy the kit without engine and don't really need to install it till the rest is done. In fact it is sometimes better not to hang a donk on the front and have it sit corroding there for years. (I had a bit of experience of that myself- we had a big wet season while mine sat in the open sided shed engine on for about 8 months. . Carby bowl corroded inside. Rubbers all cracked and crazed. )

 

In the time it takes to build the rest - you could wait and see if the new jabiru engines turn out to be to the standard you are happy with, and at the same time start a bank account to save the extra $ needed to go up to a Rotax. At the end you either have a rotax or a Jabiru and some money in the bank.

 

For what it's worth - if you have a PPL then go experimental GA then you can put four seats in it. There's not much difference in cost ( the back seat is a pre-fab single piece that slots in. Minimal work to install. You add the seat belts and it's right for the times you might want to take more people. The seat doesn't remove much ( almost none) space. Mine fits just as much camping gear as my two mates with 230s.

 

Then it's registered GA anyway so you avoid any issues or concerns ( even incorrect ones) about any form of airspace.

 

Of course all this is predicated on a jab airframe being what suits your needs.

 

 

[skippydiesel]

Rotax and Lyc props turn pretty much the same, Rotax may be a tad slower actually.

I think you will find the Rotax prop speed is about a Tad Tad & 1/2 slower. Gearbox has a 2.43:1 reduction

Typical engine /prop RPMs for my installation

 

Loitering 3000/1235

 

Econo cruise 4600/1893

 

Normal cruise 4800/1975

 

High speed cruise 5200/2140

 

Max cruise 5500/2263 (Max sustained power)

 

TO/climb 5800/2386 (Max 5 mins)

 

When taken advantage of, slow prop speed markedly reduces aircraft noise and helps with prop efficiency.

 

T

 

The O-340 in my RV-9 does exactly the same. Automotive plugs, dual electronic ignition, burns Mogas, and if I want to dawdle, the fuel flow is down around the 15LPH mark at 120KTAS, probably lower, but I don't fly that slow that often. 145KTAS at 8,000 burning 24.2LPH of Mogas is what I plan, and achieve regularly. And that will probably increase to 150KTAS when I tidy up a few draggy items. I was able to put it in the air for well under 100K using the QB kits, a brand-new engine and Dynon package.The current holder of the CAFE TriAviathon is.....A (very tidy,admittedly) RV-4...250SMPH top speed, 44SMPH stall, and a RoC of 3300FPM.

he prop RPM's don't look all that much slower than a Lyc or Cont, but effect on prop tip speed (where most of the noise & inefficiency is found) is significant.

 

Its a long time ago but from memory the Cessna's I flew cruised at 2200 RPM, TO was 2700 RPM.

 

 

[Tasmag]

Jabo-who, That is what I had originally planned, build the airframe and wait for the engine. I like the idea of the Rotax, one downside is that they don't really like Avgas though.

 

I am just being lazy wanting Avgas, it is very handy to pull up at a pump and fill up on airport.

 

 

[KRviator]

Wow, you cheapskate you, I can see half the forum running out to get the same now you've let that secret out.

Like RR, I'm not quite sure where you're coming from with that comment, tone doesn't translate well on an internet forum, but it wasn't my intent to come across as a smart-asre "because I did this", but simply to point out that you don't have to spend over 6 figures to get a 'new' aircraft. Sure, something fast-glass with a new Rotax in it will likely perform very well, very efficiently, but you can get comparable performance out of an RV by pulling the throttle back, for less dollars than you might think, and that isall I was trying to get across.For example, the complete QB kit cost me $40,000AUD, landed in Botany, including GST (US/AUD 0.75ish). The engine, a new OX-340S, with ignitions, but no carb, was $30,000AUD including GST & shipping (US/AUD 0.97ish). The Skyview package was around $10,000AUD and perhaps another $10,000 in specific tools & replacement parts. The outcome is an aircraft that will cruise around 150KTAS burning 25LPH, for 4.5 hours with two people and 75lbs of baggage.

 

 

[skippydiesel]

The O-340 in my RV-9 does exactly the same. Automotive plugs, dual electronic ignition, burns Mogas, and if I want to dawdle, the fuel flow is down around the 15LPH mark at 120KTAS, probably lower, but I don't fly that slow that often. 145KTAS at 8,000 burning 24.2LPH of Mogas is what I plan, and achieve regularly. And that will probably increase to 150KTAS when I tidy up a few draggy items. I was able to put it in the air for well under 100K using the QB kits, a brand-new engine and Dynon package.The current holder of the CAFE TriAviathon is.....A (very tidy,admittedly) RV-4...250SMPH top speed, 44SMPH stall, and a RoC of 3300FPM.

That's all wonderful and I "eat my hat" over the RV 4. You are to be congratulated on the cost of your RV 9.

 

If you have a chance look up Robin Austin/Sonerai VH-SGS. www.worldrecordplane.com/aircraft-development-story. Robin's claims for this aircraft are all verified by third parties - so no "gilded sillies".

 

Forgive my ignorance but does the S in "SMPH" stand for Statute, which is the American way of saying our miles are shorter, so making our aircraft look faster. Personally I would like us all to fly in metric but as things stand I am just a bit cynical about the American readiness to quote in US miles when it can give the illusion of better performance than knots.

 

 

[RetiredRacer]

Skippy, I read Robin Austin's story. He really deserves every record and award he has received. Amazing, WOW!!! And the Rotax was most likely the best choice for his project but you cannot claim the Rotax is what achieved his success! His engineering ability and his dedication, sweat and tears over megga hours is what achieved his success.

 

BUT!!!! The original poster wanted a engine that would pull four up at 120 kts and that is why Yenn suggested a 0-320 lycoming.!!!!!!

 

Now the TWIN TECNAM that is ANOTHER story.!!!!!

 

 

[Jaba-who]

Jabo-who, That is what I had originally planned, build the airframe and wait for the engine. I like the idea of the Rotax, one downside is that they don't really like Avgas though.I am just being lazy wanting Avgas, it is very handy to pull up at a pump and fill up on airport.

Yep I agree. Can get avgas at just about any airport that has fuel.

 

I was not aware they don't like avgas.

 

But then again there are far more airports that now have mogas apparently.

 

I have never been to an airport that has it, and been to lots of airports. But the topic was raised on another thread a few months back and lots of people posted various airports that have it available.

 

Seems like the number is growing, according to the posters.

 

 

[skippydiesel]

Skippy, I read Robin Austin's story. He really deserves every record and award he has received. Amazing, WOW!!! And the Rotax was most likely the best choice for his project but you cannot claim the Rotax is what achieved his success! His engineering ability and his dedication, sweat and tears over megga hours is what achieved his success.BUT!!!! The original poster wanted a engine that would pull four up at 120 kts and that is why Yenn suggested a 0-320 lycoming.!!!!!!

 

Now the TWIN TECNAM that is ANOTHER story.!!!!!

Would not want to take away so much as a raised eyebrow/exclamation of awe & surprise from Robins story. What I was trying to show was how much can be achieved on a relatively small engine and an "off the shelf" kit air-frame (with a lot of attention to build detail/quality).It would seem that the "packaging" of the Rotax with all the attention to cooling flow minimal drag (of various sorts) and the ultimate matching of a (still unavailable) constant speed prop, also had a lot to do with the amazing performance of VH-SGS. I think there was a time when Robin would help you (for a fee) to do the same. Most of us will never even approach the beginning of engineering excellence/in depth knowledge that Robin brought to this project. If Sonerai (or other kit builders) supplied RobIn's knowledge as part of the kit (or optional extra) we might all aspire to RV performance on the "smell of an oily rag."

 

Yeh Yeh - I went of on a tangent mea culpa and yes the twin Technam P2006T is an awesome aircraft (sadly not registerable RAA) and probably out of Tasmags budget

 

 

[bexrbetter]

Like RR, I'm not quite sure where you're coming from with that comment,

I was just mocking the "well under 100K" bit. That is not cheap, period, and I don't buy into any relativity nonsense either.

 

Not a slight on you personally in anyway and please don't take it as such, just a comment on the abhorrent costs out there.

 

 

[Tasmag]

No aircraft is ever cheap but where can you get a slippery highish performance aircraft like the RV9 for much less that 100K with all the fruit. Even a Jabiru 430 will cost about 100k once you put in a second radio and Transponder.

 

 

[RetiredRacer]

The $us/$au being all over the shop pumped up the cost of my RV9a. Not knowing if the $ was going to drop more I decided to order the complete kit and every thing I would need (except the motor and prop) when the au$ was sitting on 61c. And it was 74c when I paid for the motor kit and prop.

 

Bob

 

 

[Yenn]

After all this amount of posting have you come up with what you really want to build. It seems to vary from a Jab to high performance low wing such as an RV. What do you want to end up with?

I have built a couple of fairly good performance planes, but if there was to be a third build I would probably go for a completely different approach. Most of my flying is less than 150miles and the difference between a high performance and low performance plane is not much in terms of time. Say 100 miles [uSER=1433]@150[/uSER] kts is 40 mins and at 80 kts is 75 mins. By the time you add in the times for taxi, run up, joining circuit etc, the fast plane is not as far ahead as you would expect. The slower planes tend to be high wing, which I dislike because of the poorer visibility, but they are much cooler on the ground in our warm climate, but an even greater plus is that modern navigation device screens are much easier to read in a shady environment. I sit in my goldfish bowl and don't even try to see my iPad it is just too bright.

there are alternative engines out there. The Sonex kit suppliers have a VW type engine, at a reasonable price too. I am still not convinced that the Jab engine is bad, mine keeps on going with no problems. No problems also with Rotax and I believe they are still producing the 682 two stroke. I ran a Rotax 503 for several years and it was reliable.

[Tasmag]

Yenn, not really any further progressed. I still like the J430 for the ease of construction and simplicity. The idea of a low wing SP4000 appealed for the engine more than the airframe, although the carrying capacity is a bonus.

 

I want an aircraft that can do long distances with a fair bit of gear, hence the 4 seat bias. I suspect I will end up with what I originally planned, a J430 with a jab engine.

 

 

[bexrbetter]

No aircraft is ever cheap

Most aircraft are not cheap, but 200kgs of aluminium, a bit of fiberglass, and an engine should be.

 

 

[Tasmag]

Bex, What do you anticipate your design will be built for?