What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

RV-8 Turbine update

pierre smith

pierre smith

Well Known Member
Mornin' everybody,
I received an e-mail update from Mr. Jim Benson this morning, with these pictures of the new cowl inlet ducts. He said that his test pilot will be resuming more flight tests in early November and to check Innodyn's website.

Note the cockpit view and the tach. As in my PT6-15 airplane, it reads in % power because the RPMs are too high to display (mine are 37,500 RPMs on takeoff!), so instead it is 92%, etc.
my.php
[/URL][/IMG]
my.php
[/URL][/IMG]
my.php
[/URL][/IMG]
Regards,
 
Good job Pierre!

That's the most real info I've ever seen posted on that project - thanks for sluething!

I'd wondered what it would look like....

Paul
 
When?

Mornin' Paul,
When are you heading back east in your -8? My season is just about over and I'd love to team up somewhere near the Gulf and two-ship for a ways. :)

Regards,
 
Neat idea Pierre - I've gotten sucked into a mishap investigation board for a few weeks,maybe we'll have to meet halfway, like NOLA for lunch sometime when I get done. Boards like this are interesting, but they take me away from regular stuff, like simming and planning missions....

Paul
 
RPM

Just to let you all know the RPM in this plane is around 2800 (prop) and the turbine spins at 61,000. We actually had to cut down the prop as it was too long. It was about mach .84 (prop tip) if I recall and creating too much drag. It is now around .81 and we have not gotten any compressor stalls. Balanced it with Acers model 1000. And it appears to run really well. Unfortunately the test pilot took ill the next day and we have not flown it. He should be ready to go in early November.
Jim Benson
 
Last edited:
Welcome to VAF Jim! Are you the owner of the -8? Glad you're able to provide info either way!! We're all very excited about this project! :cool:
 
Welcome Jim!!!

...and thanks for being a trail blazer with the Innodyn! That is a heck of a bird you have there and we'll be anxious to see your successes!

- Peter
 
I agree!

Welcome aboard Jim! That is a mean-looking and fascinating project - thanks for coming in and sharing it with us.

Paul
 
Any update?

It's been about a month since flight testing was supposed to resume. Has the RV-8 flown again?
 
Sent two emails this morning to Innodyn. The first was to Charlie Sullivan (I think most of us know this name...), and the second was to the information request address. Both of them came back undeliverable because the mailboxes are full... :rolleyes:
 
Innodyn's big mistake

What Innodyn doesn't seem to understand is that if they refuse to provide dyno/flight data and other information then those of us that are trying to figure out what's gong on will have to speculate based on what little information we have. I'd guess that very often, the speculation will paint a picture that looks worse than the truth. Also, Innodyn should try and understand that most of us speculators really hope that they've invented a great new engine. That's why we're bothering to pay attention to them.

Here's my speculation:
1) The RV-8 has flown again
2) The performance with the cheek inlets improved little compared to the naca duct. After all, how bad could it have been?
3) The performance is consistent with the engine producing 130 to 150 HP.
4) The builder has contacted Innodyn
5) He may not have been able to get a response
6) If he got a response, it was an assertion that something else is wrong with the installation.
7) The builder may be working on implimenting Innodyn's new modifications.
8) The builder may be discouraged and weighing his options but hasn't yet given up hope to the point that he's willing to go public with the results.

Innodyn, I hope you're listening. If you don't like my speculation, then please come up with some real info.
 
I REALLY hope they are listening too! I'm all over the place with the direction I want to take for an engine. BUT, I'm far enough away from needing to choose, I can afford to be. Speculation is just that. I for one, hope that all eight of your items are wrong, but I know they may very well be true. Although, with no info to base them on, we shouldn't think too much about it. Innodyn has been notoriously late on everything they've said or promised. I'm glad I don't have money riding on one of these yet, but if they turn out to be legit (performance, fuel flow, price), my money would go to them in a heartbeat.

Everytime I fly the King Air at work, all I can think about is how sweet it would be to power my -7 with a turbine engine. I still watch the Innodyn video's once a week or so, dreaming of the day that this would become reality... :rolleyes:

JIM, WHERE DID YOU GO??? WE NEED AN UPDATE!! :D
 
Well not all of us

kcameron said:
Also, Innodyn should try and understand that most of us speculators really hope that they've invented a great new engine. That's why we're bothering to pay attention to them.
Click to expand...
Well I don't think anyone wants anyone to come to harm or loose money or worse. Since this nice Gentalman has posted his pics, we are of course all pulling for him. However I will cop to being interested because I think its a train wreck, in the sense expectation and promises will crash into reality. There is no way its making the 7 gal/100hp. It also looks like engine operations, rpm/power/fuel management may be more difficult than a Lyc.
cjensen said:
I REALLY hope they are listening too! <snip> Everytime I fly the King Air at work, all I can think about is how sweet it would be to power my -7 with a turbine engine. JIM, WHERE DID YOU GO??? WE NEED AN UPDATE!! :D
Click to expand...
CJ are you kidding. Do you pay the bills at your company? What are those PT6's costing per hour, inspections, overhaul? Turbine = Nice :D , Turbine cost to an individual / sport pilot = sell kidney :mad: Yea I'm glad every time my RB211's spool-up, but it's hard to beat the suck, squeeze, bang, blow of the Lyc. For a 100-260 hp engine that does not make a living and flys 100-150 hours a year, tops, a piston engine is hard to beat. Heck even Lycs are making a living flying pipe line, freight, charters and small airlines. I'v been involved with piston aircraft fleets of close to 40 and most where Lycs, they do earn their keep.

There is no doubt turbines are sexy, but so is a Ferrari, Lamborghini and that new $400,000 Rolls Royce but its not like you will buy one so the wife can all kids to soccer practice and get groceries. Unless there is a technological breakthrough, a new "Paradigm" if you will, I hate that word but it fits here, than turbines will never be for average pilot/plane owners. Its like getting your own Nuclear reactor for your house, nice idea but not practical. The BEST you can do is find a old Lear, Citation, MU2, King-air, European Fighters/Trainer to get your Turbine jollies off.

What was it, 10-15 year ago, you could get a Casa Jet, Fuga Magister (V-tailed, tandem, later made into the personal ParisJet), L-29 or one of those Brit trainer/attack jets like the Provosts, for less than a RV cost today. They are still Cheap. I remember the first import L-39's turbofan trainer/attack (looks like a Douglas A-4), they cost less than $100,000. Now insurance, fuel and practicality come into effect, but if I wanted a jet I'd buy one already flying, it would be cheaper and actually do something than a home made turbine that is trying to only be a piston engine replacement.

Jets/Turbines are made to go real fast or haul lots of stuff. The RV airframe is not really suitable match. The best Kit plane/Turbine is the Lancair Prop-Jet with a used Walter (PT6 copy). You are looking at $500,000-$750,000. Now you have a pressurized personal 4 place plane. Makes sense.

I am looking at the VLJ's (very light jets). The Diamond, Maverick, Vantage, Eclipse, Adams and Cirrus jet. We shall see if the reality and dream end up in the ditch again or it takes off. Cheap Turbines are nice idea, but most of the improvement is with the 900-2000 lb thrust turbofan engines. By today's standards, they have to get cheaper, both initial purchase & operation cost, by a factor of 4-10 times before you and I can afford one. I have looked into the little 200-300lb thrust APU/Drone Jet engines and they are too small. I don't want to fly a BD-5 sized plane because frankly they are dangerous. The accident rate speaks for itself.
 
Last edited:
gmcjetpilot said:
<snip>It also looks like engine operations, rpm/power/fuel management may be more difficult than a Lyc.
Click to expand...

WHY?

gmcjetpilot said:
CJ are you kidding. Do you pay the bills at your company? What are those PT6 cost per hour? Turbine = Nice :D , cost to an individual / sport pilot = sell kidney :mad: Yea I am glad every time my RB211's spool- up, but it's hard to beat the suck, squeeze, bang, blow of the Lyc.
Click to expand...
Well, you sniped out the last part of my post about DREAMING of this happening one day. I hope it does, but fully expect that it wont. BUT comparing operating costs between the 750shp PT6 and the 185hp Innodyn is certainly apples to oranges. Turbines are nice, and I thoroughly enjoy flying them at work...because I DON'T pay the bills. I know that the fuel buen claims from Innodyn are probably far fetched based on what well known turbines burn. The burn is going to be too high to make it work with the small tanks of an RV.

It is nice to DREAM though! :D
 
Chad this is my worry

I hear you chad. The reason for the power management issue is, as you know you have fuel, prop (torque) control (and fuel control). In a real turbine you have torque reading, hydraulic prop and a fairly complicated fuel controller.

The Innodyn has nothing or very rudimentary controls that don't work together. For example MT I believe does not approve of the application.

>No torque meter
>You have to set the fuel (w/ little or no protection)
>Direct prop - turbine (gear box) connection (not like a PT6)
>No auto ATMO compensation, have watch TIT (turbine inlet temp)
>Slow acting elec "constant speed" prop (rpm not torque control)

My worry is a pilot will be subject to:
>hot start
>over-speed
>"lug" (hung, no acceleration, un-spool)
>high egt and burning it into molten metal.

From what I gather they have constant RPM engine. So its just spooled to near 100% all the time and thrust (torque) is managed with the electric MT prop! Boy if that prop slaps to low pitch or high pitch at the wrong time it could be bad. Like I said MT is not on board. Could be wrong but that is what I heard.

I gather the pilot needs to manipulate the prop and fuel in concert (very carefully). The pilot must add pitch as you add fuel "manually". Well that is cool and takes some lever jocking, but without a real hydraulic prop and fuel controller with feedback/control between prop and fuel it might be a bit touchy.

Lets face it, a Lyc is a single lever engine. Leave the prop (if you have it) and mixture full forward and move the back knob and fly all day. At worst run at 2,700 rpm and burn way to much fuel. The penalty of doing some wacky-dos with the throttle or prop on the Innodyn may be bad? (loss of engine / power)

Look I'll cop to being a Lycoming fan. I am also use to jets w/ automatic engine management, auto start, over temp and over speed protection. Jets are easier to manage than props, but with the old Garrett's TPE331, they where fairly mature engines and had to be watched. Like the Innodyn they are direct drive engines. The PT6 is the easiest, most forgiving turbine you can fly. That is why they are so popular and successful.

Look at early jets that seemed to crash. The pilots did not understand the lag time to spool the old jet engine for a go around or arrest high sink rate close to the ground. The Innodyn is an "early jet" and seems they have done it on the cheap. They also are relying on a electric prop that is not designed or intended to be used like this. Elect props are slow to react and this as I worry. It may cause a problem. Hope I am wrong. :eek:
 
Last edited:
Good post George. I agree with everything but one thing...according to Innodyn's website, the fuel is fully computer controlled. Here's the words from that page-

Piloting/Controls

Innodyn Turbines: An IntroductionFlying an Innodyn Turbine is much simpler than you
might think.

There are 2 basic controls to Innodyn Turbines ? the propeller RPM throttle and the propeller pitch. The computer manages the amount of fuel the Turbine draws, and alerts the pilot with a warning light if too much power is being requested. The computer control will not let the Turbine over-heat, and it will not let the Turbine over-speed.

Start
To start the Turbine, simply put the propeller to zero pitch and turn the starter key. The computer completes the start sequence, gradually spinning the propeller, adding fuel and turning on the igniter.

Once the Turbine is started, set the RPM lever and add propeller pitch to generate power. Instead of flying with the throttle, we recommend that you initially use only propeller pitch. The computer will handle fuel control and the Turbine?s operation. Because the Turbine is directly spooled, there is no noticeable lag in changing propeller RPM and the aircraft is quite responsive.

Taxi/Takeoff
To taxi, add a modest amount of pitch to the propeller to maintain a safe ground maneuvering speed. To take off, line up on the center line, and add propeller pitch. The propellers we recommend are able add pitch quite quickly, and the airplane will rapidly gain takeoff speed. After takeoff, simply maintain safe airspeeds. If you want to slow your climb rate, take a little bit of pitch out.

It will not be possible to accidentally enter a negative pitch into the propeller while airborne, as this would be a very alarming development.

The pilot should quickly have the ability to manage their takeoff roll, and their rate of climb.

Cruise
The Innodyn Turbine will cruise comfortably at 100% of power, and so it is not necessary to decrease either propeller RPM or pitch. Our Turbines actually operate most efficiently at full power, so there isn?t a compelling economic reason to decrease the power either. Obviously, you should not exceed Vne for your aircraft. Another important benefit of Innodyn Turbines is that they continue to produce power very effectively at higher altitudes.

Landing/Go-around
The landing process is relatively straightforward, and allows the pilot good control over approach speeds, landing speed, and rollout. Approaching the airport one gradually decreases propeller pitch to obtain the desired pattern speed, and likewise manages pattern and approach speed by making modest adjustments in propeller pitch. Innodyn?s pilots report that they have relatively quickly learned how to dial in a desired speed. On short final the pilot either continues gradually decreasing propeller pitch or adds propeller pitch and executes a go-around. As you fly the approach at a proper margin above stall speed, adding sufficient propeller pitch to produce additional thrust and execute a go-around is quite a quick process.

Because the Innodyn Turbine is directly driven, rather than spooled, there is virtually no lag associated with increasing speed. Likewise, because you want to land with plenty of power available, we don?t advise significantly decreasing propeller RPM during approach.

After landing, the pilot can continue decreasing propeller pitch to slow the landing roll. With experience, a pilot can very effectively shorten the landing roll.
Click to expand...

I have not heard that the MT was not intended for this. I thought they had worked with MT to develop the prop...don't know.
 
With no spool-up time, since it's always operating at 98-100% RPM, and a FAST actuating hydraulic prop, that sounds like one wonderful high-power engine for a small aerobatic aircraft - but in it's current state, even I'm scared of it, and I'm a very pro-alternative kind of guy. I've got some turboprop and some true turbine time, and you're right - it's got to be the easiest engine management you'll ever find. This particular setup on the Innodyne scares me.
 
Bummer

I, too would like the turbine dream to be true. With something over 11000 hours flying turbine power, I share the fantasy of of kerosene power for my RV8. Not gonna happen anytime soon.

The whole Innodyn thing has a familliar ring, I will be polite here and say that the people involved in the Innodyn project are, um, optimistic. With the time they have spent I find it hard to use the term "scam" but if they aren't kidding the public, they are kidding themselves.

The technology they are pushing is rehashed 1960s APU (auxillary power unit) science. Google "Solar T-62" and read all about it. One of the more interesting reads is at http://www.provide.net/~pratt1/ambuilt/turbine.htm

This isn't really a technology problem, it is a financial one. The market is so small and the development costs so high that it is unlikely that it will ever happen. What we need is some available "spin off" technology. Anyone know of a 200 HP UAV turbine?

Nice weather today, I'm going to go fly my Lycoming.

John Clark
RV8 N18U
KSBA
 
...the computer controls...

OK I ...

1) am a low time pilot
2) know very little about turbines or flying turbine aircraft
3) know nothing about Innodyne's actual software/hardware implementation.

But I am concerned with what might happen if the computer controller goes out to lunch. I have little concern of a software error, but what would/could happen if the computer (and I am assuming there is only one processor) goes out at a critical time? What if it goes out and leaves the throttle full open? Are there any efforts made at redundant processors?

I am just writing off the top of my head here, (I am an avionics software engineer) if I were designing such a system I would be planning on like three separate redundant processors on isolated independent power systems each monitoring the other two for errors/differences. And each processor with separate sensors. And then I would still want some sort of mechanical override.

Or would all of this be overkill? If something goes wrong with a turbine, how much time does a pilot have to correct the problem before a disaster occurs?

I would sort of think that if they had a redundant controller design here they would have highlighted it as a feature. That they didn't suggests to me that there is not such a feature.

--John Babrick
 
I share your concerns

John,
You are right on target with your concerns. The engine in question was designed as an APU (auxillary power unit in an aircraft) or in some cases a GPU (ground power unit on a cart.) In both uses the engine would run at a constant "100%" power. That is, governed to whatever the designer deemed the best for output and service life. In this application the "computer" needs only to regulate the fuel to maintain RPM if the load varies. As a APU, the unit can be set up to shut itself down if something overheats, overloads or whatever. So the airplane gets dark sitting on the ground, big deal. Engines designed to power aircraft have redundant systems to protect the engine. Remember, a turbine engine is controlled only by fuel available. Unlike a piston engine, if the controller goes nuts and really pours the fuel in it will over rev, overheat and very likely come apart with a bang. It had been a while, but I recall that a PT6 has 3 independant systems to protect against a situation. I only see one on this engine. I think that the suggestion that the engine can be run at 100% RPM and controlled only with the prop is the result of not having the technology to properly control the engine.

Again, all this could be made to work given enough time and MONEY but I really don't see the numbers that would make it happen.

If you haven't read it yet, this is interesting:
http://www.provide.net/~pratt1/ambuilt/turbine.htm


John Clark
RV8 N18U
KSBA
 
Model airplane gas turbines now generate up to 50 lbs. of thrust, run on kerosene and have their own FADECs, all for about $7K US. This sort of digital control is easy compared to those for piston engines. Can sense N1 or EPR and TIT for limiting. Should not be too expensive to develop. I don't think this aspect is the show stopper.

Having the thing go 1000+ hours between overhauls might be more difficult.

http://www.cat-ing.de/turbines/jetcatturbinen/strahlturbinen.htm
 
An issue of "scale"

The model turbines are very impressive but you need to remember how the size effects the design and materials. Back in my youth I had model airplanes with piston engines that produces amazing horsepower at very high RPM and were dead simple. Plain bearings, no piston rings, and brutally simple induction systems. The reason this all worked was the size (or lack of it.) You can't just scale up an engine, piston or turbine and have it work the same way. Expansion rates and material properties don't "scale up" well.

There is no reason a GA/experimental turboprop couldn't be developed. The real issue is market and cost. Here is part of a release from P&W Canada:

Last Updated: Wednesday, December 13, 2006 | 11:57 AM ET
CBC News
Pratt & Whitney Canada Corp. said Wednesday it plans to spend $1.5 billion, including $350 million from the federal government, to develop lighter, more fuel-efficient gas-turbine engines.

Ya gotta build and sell a lot of engines to recoup that kind of investment.

John Clark
RV8 N18U
KSBA
 
China could make cheap turbine power happen. Labor is cheap, lots of engineering talent. If I were interested in making an experimental turbine, I'd hire a Chinese engineering firm with the necessary experience and have it manufactured there. I'd call my company Harbor Freight Turbines :)
 
John Clark said:
The model turbines are very impressive but you need to remember how the size effects the design and materials. Back in my youth I had model airplanes with piston engines that produces amazing horsepower at very high RPM and were dead simple. Plain bearings, no piston rings, and brutally simple induction systems. The reason this all worked was the size (or lack of it.) You can't just scale up an engine, piston or turbine and have it work the same way. Expansion rates and material properties don't "scale up" well.
Click to expand...

My comment was directed towards the FADEC side, not the mechanical design.

I believe that it is possible to use off the shelf industrial turbocharger parts to construct a reliable experimental gas turbine. This was done several years ago as documented in Aviation Week for use on UAVs using Garrett TO4 parts and many internet plans to build gas turbines have resulted in backyard successes.

The compressor and turbomachinery is is well proven and cheap, development would center on burners and reduction gearing mainly which are no small tasks themselves but with some actual engineering applied by a talented small team, I don't think hundreds of millions need to be spent. P&W is working on certified engines, not ones for experimentals.
 
The FADEC couldn't be too difficult...

As to a FADEC, here is my feeling about the software/hardware.

What the FADEC needs to do is probably not very complicated. I would expect to be able to program it to do anything it needed to do with some high speed modern version of the 8051 family - an 8/16 bit processor. At 50 mhz speeds it would be plenty fast to control the engine. One would want three of them, in separate armored modules with separate sets of sensors (temp, rpm, oil pressure, oil temp,thrust lever, etc) and power supplies. Probably some sort of small battery backup for each in case the main airplane power goes out. The processors are small - on boards about five or six square inches. The ones I am thinking of already have built in ethernet and webservers, so some simple ethernet wiring and literally some simple webpage programming would provide you with an instant detailed realtime webpage diagnostic system. In any event, the ethernet would allow the processors to interact and compare results to determine if any of the three have failed and to negotiate what to do if one or two do fail.

An additional processor could probably be assigned the task of monitoring vibration and fire protection - essentially a digital signal processor that looks for vibration signatures and temperature out of normal. Could raise an alarm to the other processors to warn the pilot of impending engine failure.

I would envision a separate processor mounted on the control panel which would have some small color LCD video screen which would be connected to the FADEC processors via the ethernet and which would display the engine parameters in realtime.

The software would operate in one of several modes - startup, taxi, takeoff, climb, cruise, descent, approach and shutdown. You probably wouldn't need to use the thrust lever much - instead, you would have several buttons on the control panel labeled with these modes that you would push to tell the engine what you wanted it to do. The controllers would also need to control the propeller pitch. Couple all of this with some sort of GPS coupled FMS and autopilot and you have an extremely automated turbine powered RV.

Really, I can envision implementing the hardware for this kind of FADEC for under $1000. The boards I am thinking of ( www.rabbitsemiconductor.com ) are ready made and cost like $200 - $300 each. Perhaps the sensors would run the bill up a bit, but the computers would not. Very, very doable. I wish I had a turbine engine to try this out on.

I guess my question is, (and I have no idea of the answer) how difficult is it to actually build the turbine? One shaft with a compressor on one side and a turbine section on the other side, able to stand the heat, pressure, torque and vibration? A lubrication system? Fuel injectors? Gear reduction? Alternator drive? Propeller pitch control?

??? I don't know. But I do know that the computer control for such a thing would be straightforward.

--John Babrick
 
Last edited:
The biggest issue (IMHO)

Last year when I was making my engine decision, I was lured by the Innodyn turbine. After a lot of conversation with Innodyn, the guys at Firewall Forward, and even the guy making the throttle quadrant and guage package for Innodyn - I went so far as to plop down the $100 for the engine "manual" (and I'll use that term loosely). I seriously could write a book here telling you of the ups and downs of this engine and the company, but this is what it all boiled down to for me.

It was mentioned in an earlier post how the pilot must control the throttle and prop simultaneously... but the deeper and more dangerous issue there is how the pilot has to control the prop. It's a freakin toggle switch on the instrument panel!!!

Now you can belabor the pros and cons of the efficiency or operating limits of the turbine... but when you start trying to fly an airplane and control your speed with a toggle on the panel, you're asking for trouble. And that's exactly what Innodyn found out early in their testing.

BUT - when I discussed this with them, and the need to develop a way to control rpm and pitch with a quadrant, they agreed but didn't see it happening. Their answer to me was to wire the prop control into one of the flight stick grip switches?!?! They did this - and again had some bad results - but continued with this approach and I believe their flying test aircraft have this configuration to this day.

In the end, I think Innodyn chose the route they thought best. Limited finances allowed for one direction. They put all of their dollars into this "super-atomizing" fuel controller, and no one stopped to ask a pilot what would be the safest way to actually fly the thing (prop control). This coupled with their idea that "they'll build the engine, someone else will build the motor mount and the firewall forward" will result in a failed company; agian, in my opinion.

So, to the group who swoops in and picks up Innodyn for pennies on the dollar, I say this. Develop a working engine mount and firewall forward kit. Engineer an electric or hydraulic option to control the prop like normal turbine aircraft do (think T-34C) and you might sell some of these. RV builders already like this idea - but you've GOT to deliver a useable product. Innovaton from your initial offering will come - later.
 
modes and toggle switches...

...when I wrote about controlling the engine with switches to select modes, I did not mean to imply that there would be no thrust lever. The mode switch would just be to tell the engine what the pilot is intending to do (take off, land, cruise, etc) and the lever(s) would allow the pilot an automated way of increasing or decreasing the thrust without needing to manually coordinate any number of complicated parameters. Let the computer do the tedious mechanical controlling and let the pilot make the big decisions.

Gosh, I really wish there was an engine for me to build this FADEC for.

JCB
 
Update

Morning guys. Mr. Jim Benson sent me this email after I queried him about the RV 8 turbine project:


quickly, we have flown it since the new intakes and they were the
ticket. However we were doing some ground testing with the governor
system and over heated the engine. We were kinda pushing it to see what
she could do and we found the limit. The engine still ran and seemed to
have plenty of power but it had a new sound that we did not like. So
off it came and back to the factory. As it turns out we lost an inch
off the turbine wheel (what exactly that means I am not sure) and the
bearing were slightly warped. So they are rebuilding her for us and it
looks like we will be trying a new prop when they send our engine back.

Thinking about building another 8 to keep ourselves busy. What do you
know about this new fast back conversion? check out
http://showplanes.com/index_1024.htm And check out his cowling. Let
me know your thoughts.


Regards,
 
That's gotta hurt!

pierre smith said:
...As it turns out we lost an inch off the turbine wheel (what exactly that means I am not sure) and the bearing were slightly warped. ...
Click to expand...

Lost an inch off the turbine wheel?!? Ooooo, that's gotta hurt!

--JCB
 
Hmm. Sounds like maybe Innodyn has not yet established what the EGT limits should be, or the engine fuel control makes it easy to inadvertently greatly exceed the EGT limit.
 
OldAndBold said:
As to a FADEC, here is my feeling about the software/hardware.

What the FADEC needs to do is probably not very complicated. I would expect to be able to program it to do anything it needed to do with some high speed modern version of the 8051 family - an 8/16 bit processor. At 50 mhz speeds it would be plenty fast to control the engine. One would want three of them, in separate armored modules with separate sets of sensors (temp, rpm, oil pressure, oil temp,thrust lever, etc) and power supplies. Probably some sort of small battery backup for each in case the main airplane power goes out. The processors are small - on boards about five or six square inches. The ones I am thinking of already have built in ethernet and webservers, so some simple ethernet wiring and literally some simple webpage programming would provide you with an instant detailed realtime webpage diagnostic system. In any event, the ethernet would allow the processors to interact and compare results to determine if any of the three have failed and to negotiate what to do if one or two do fail.

An additional processor could probably be assigned the task of monitoring vibration and fire protection - essentially a digital signal processor that looks for vibration signatures and temperature out of normal. Could raise an alarm to the other processors to warn the pilot of impending engine failure.

I would envision a separate processor mounted on the control panel which would have some small color LCD video screen which would be connected to the FADEC processors via the ethernet and which would display the engine parameters in realtime.


I guess my question is, (and I have no idea of the answer) how difficult is it to actually build the turbine? One shaft with a compressor on one side and a turbine section on the other side, able to stand the heat, pressure, torque and vibration? A lubrication system? Fuel injectors? Gear reduction? Alternator drive? Propeller pitch control?

??? I don't know. But I do know that the computer control for such a thing would be straightforward.

--John Babrick
Click to expand...

I'd suggest keeping it simple and just have the hardware and software (less code= higher reliability and less development time) to do the job of supplying the right amount of fuel, keeping it from over temping and controlling the prop. You don't need web connection or diagnostics on simple turbines. Wanna check the turbine on a Garrett, 6 bolts and you can. A simple 68HC11 with a few hundred lines of code would be all that's required here. Use PWM and overlapping spray from 3-4 automotive type fuel injectors as nozzles. Drive the alternator off the prop flange like a Rotax.

C/S prop controllers retail for around $300. The model airplane turbine guys are selling the whole engine for $2000-$7000 which includes starter, FADEC, burners etc. Turbo speed sensors/ displays are also available for a few hundred bucks. A lot of the same technology is applicable and these are hardly in mass production.

I envision two Garrett compressor wheels say a T106 blowing into a T88. These wheels are less than $250 each and capable of pressure ratios of around 4 to 1. Over pressure ratio around 8. The T106 is capable of mass flows in the 220 lb./ min. range, certainly adequate to provide air for 200hp.

Max rpms would be in the 65,000 rpm range. A turbine in the 4-4.5 inch range, maybe T18 stuff could be used- costs in the $450 range with housing in the same ballpark. Use the T106 compressor housing, about $350 and you'd have to machine an annular housing for the second stage. A bearing section could be CNC'd containing three sets of bearings for shaft support. The fuel nozzles and burner could be built into a 321 or Inconel tube leading from the second compressor stage to the turbine inlet flange.

I see the big hurdle in design and validation as being the reduction gear as about 20 to 1 reduction is required between the turbine shaft and prop shaft. This would be relatively expensive to design and produce and test. I also see some trial and error in balancing flow between the two compressor sections over a fairly wide operating range so one does not force the other into surge. No doubt the first attempt would result in plenty of revisions.

By using proven, existing off the shelf turbo parts and electronics much of the high costs of producing new parts could be avoided.

Cool to think about. I doubt the fuel flow would be anything to write home about with one turbine stage and only 8 to 1 PR but there seems to be lots of interest in small turbines despite this drawback. At least overhaul/ labor costs would be low with this approach. :)
 
Bye bye Innodyn...

pierre smith said:
Morning guys. Mr. Jim Benson sent me this email after I queried him about the RV 8 turbine project:


quickly, we have flown it since the new intakes and they were the
ticket. However we were doing some ground testing with the governor
system and over heated the engine. We were kinda pushing it to see what
she could do and we found the limit. The engine still ran and seemed to
have plenty of power but it had a new sound that we did not like. So
off it came and back to the factory. As it turns out we lost an inch
off the turbine wheel (what exactly that means I am not sure) and the
bearing were slightly warped. So they are rebuilding her for us and it
looks like we will be trying a new prop when they send our engine back.

Thinking about building another 8 to keep ourselves busy. What do you
know about this new fast back conversion? check out
http://showplanes.com/index_1024.htm And check out his cowling. Let
me know your thoughts.


Regards,
Click to expand...
Thanks for forwarding that on Pierre! I think that just...-snip-snip-...cut that idea right up for me. :rolleyes:
 
OK, but would it be cool to use?

rv6ejguy said:
I'd suggest keeping it simple and just have the hardware and software . . .

I envision two Garrett compressor wheels say a T106 blowing into a T88. These wheels are less than $250 each and capable of pressure ratios of around 4 to 1. Over pressure ratio around 8. The T106 is capable of mass flows in the 220 lb./ min. range, certainly adequate to provide air for 200hp.

Max rpms would be in the 65,000 rpm range. A turbine in the 4-4.5 inch range, maybe T18 stuff could be used- costs in the $450 range with housing in the same ballpark. Use the T106 compressor housing, about $350 and you'd have to machine an annular housing for the second stage. A bearing section could be CNC'd containing three sets of bearings for shaft support. The fuel nozzles and burner could be built into a 321 or Inconel tube leading from the second compressor stage to the turbine inlet flange.

. . .

By using proven, existing off the shelf turbo parts and electronics much of the high costs of producing new parts could be avoided.

Cool to think about. I doubt the fuel flow would be anything to write home about with one turbine stage and only 8 to 1 PR but there seems to be lots of interest in small turbines despite this drawback. At least overhaul/ labor costs would be low with this approach. :)
Click to expand...

First, I had no idea that turbine wheels could be purchased readymade and for non-astronomical prices. That, I would think, would be a huge step forward in trying to build something myself/ourselves. Those would seem to be the most critical and difficult parts right there.

Second, OK let's assume that we'd never get fuel flow to be even half as good as a piston engine. Would there be a "coolness" factor in flying a turbine that offsets the increased fuel costs? How much of a coolness factor could there be or would need to be before someone would say that they wanted the turbine on their airplane instead of the Lycoming?

Seems to me that Vne is the big limiter to the RV - it can only safely go about 220 mph no matter how big an engine you put on it. If you put some lightweight turbine that produces 350 hp on it, would all that you get be superfast climbs?

Darn, I sure wish I had a mechanical engineering background...

--JCB
 
Last edited:
There would be the rather significant coolness factor of being able to climb into the high 20's or low 30's - and then doing it just because you wanted to. There would be a constant stream of questions from heavy iron about what the heck is THAT doing up here??? The weight of a good oxygen system on board would be neglible when looking at the increased power you would have - but Vne and more importantly Mmo (since that's what drives flutter) would be a very high concern at altitude.

Dollar factor - high
Coolness factor - high

Dunno about [dollar factor] = [coolness factor], though....

Of course, the next natural step, being experimental, is to design your own plane with a pressurized cabin and take advantage of the ability to draw bleed air for pressurization and air conditioning. And then add anti-ice protection, retractable gear, all-weather capability, FAA certification....oh wait - that's already been done. :D
 
airguy said:
There would be the rather significant coolness factor of being able to climb into the high 20's or low 30's - and then doing it just because you wanted to.
Click to expand...
The physiological risks go up significantly with sustained unpressurized flight above 25,000 ft. There is a real risk of the "bends" (decompression sickness), unless you plan to spend quite a while breathing pure oxygen before the flight. The consequences of O2 system failure may be fatal. The risk of the bends goes up with age too.

I spent a lot of time with cabin altitude around 23,000 ft when I was flying in the military, and I sometimes got pain in my left elbow after two hours or so at altitude, which was probably due to the bends.
 
The cool factor is about the only tangible reason reason for turbine power on an RV airframe. The fuel flow is killer and the Vne is pretty low for high altitude work. If we talk about a 200hp sea level turbine though, it wouldn't be much faster than a IO-360 up high at it suffers a fairly significant power loss with altitude. If it was flat rated to 200 hp at 15,000 feet or so, then you'd have a big problem.

I have friends with turbine powered homebuilts. Impressive sounding and the climb performance is astounding on one at 11,000 fpm (1000SHP Garrett) but the fuel flow is staggering below 15,000. The turbine IVPs are the best way to go as they are pressurized and fast. Sucking on O2 up high is not a nice way to spend a day and ATC does not really want 200 knot airplanes up at 25,000-30,000 feet. Another guy has a turbine Rotorway. Way cool but short trips.

A low cost turbine will likely burn about twice as much fuel for the same speed as a reciprocating engine at low altitudes so unless you are rich and just love that sound, it is probably not practical for most people.

If you are a mad scientist, I don't want to discourage you from experimenting. Try this: http://www.nyethermodynamics.com/nt5/index.html :cool: :eek:

On the other hand here is some discussion on similar subjects: http://www.provide.net/~pratt1/ambuilt/turbine.htm

I'm sticking with my turbocharged piston engines for now, they sound pretty cool at idle and wound up tight with that turbine whistle (open exhaust). That will have to do for now. 10-15 gal./hr. is all I can stand.
 
Last edited:
what what

Bump?

Whats Happening. Any word, update? Innodyn news was last up dated 5 months ago on 10/27/06? :confused:
 
George,

I've been wondering the same thing, and have tried to call and email NUMEROUS times since the first of the year with zero response. I'm wondering if anyone is home???
 
The last post on the Innodyn website relative to the RV8 was 10/27/06.

The last update to their website was 4/12/07.
 
My uncle runs the company...

Sounds like something my uncle would run. He was from his teenage years a mad engineer. He had all sorts of weird stuff in his basement lab - radios, radars, etc. He once designed his own version of an internal combustion engine and was on the verge of getting a patent when the search found something similar had been done years before. And then there was the piston engine he built completely from raw metal just to show he could do it. His garage had all sorts of Volkswagon vehicles and engines in various stages of reconstruction. And then he had his own X-ray machine that he used to examine engine parts for cracks... I can just imagine Innodyn being something like my uncle's garage, with an almost working turbine engine sitting on the floor off in the corner next to a pile of shop rags with him saying that he was going to get back to it someday...
 
hello From the RV-8 Turbine guy

I was doing a google search on my name and found this thread. I had no idea there has been so much talk going on about my plane, RV-8T N333JB, albeit a year ago.

Here is the latest: The plane last flew in Dec. 06, it has a total of 8 flights. The test pilot and I were doing a ground test on the FADEC system and overheated the engine slightly. Innodyn said to send the engine back so they could look at it. So I FedEx'd back and have not seen the engine since. The inventor said he has rebuilt it and all is good but refuses to send it back. I would even pay for shipping. There is turmoil in the company as to who owns what and how things are going to be run.

I am hoping in the near future things can be worked out so I can get my engine back and we can resume flying and testing.

So we have started to build another RV-8. We are putting an IO-360 on it from Aero Sport Performance out of Kamloops, Canada. This one will also hae the Fast Back conversion. Should be flying in the next month or so. Meanwhile, the other plane sits in the hangar collecting dust.

I am going to give Innodyn this year to get everything worked out. If not we will put a piston on the thing and fly it.

I am bad about coming here to look to see what is going on. I have checked off to send me email notification when some one posts to this thread.

jim benson
 
Last edited:
You must log in or register to reply here.
Back
Top