One small step for man,one GIANT leap for modeling!

[madmax]

One small step for man,one GIANT leap for modeling!
Published on: January 1, 2006
Written by: Bob "Biff" Sadler

So I get a call from long time flying bud Eric Meyers. "Hey guy, I'm headed to Triple Tree to fly some new toys, wanna see 'em?" I responded in the positive as I finished a cup of coffee. My flying vehicle always heads to the field unless I take over in manual mode. It doesn't like to head anywhere airplanes aren't in force.

For those of you who don't know Eric, he's been a real hoot to have as a flying bud. He's been in the hobby over 35 years flying anything that goes up in the air. Racers, jets, helicopters, sailplanes, electrics etc. Super guy with mad skills and a passion for modeling. Professionally, he is the chief marketing manager for JR and Spektrum brands. Though residing in Greenville, SC., he keeps an office at the Horizon Hobby building in Champagne, Illinois. A tinkerer by nature, Eric keeps his flying vehicle loaded down and ready for aviating at the end of a working day.

The planes he pulled out were some pretty neat machines! For any of you who have seen the monster gliders used in aero towing, you'll probably recognize the Fox. Take an aerobatic sailplane that is intended to be towed aloft and chuck a turbine on the top. What do you have? A BLAST !! I watched him go through the auto start sequence then taxi the monster out to the runway. Full power, level the wings and huck it hard! The plane is aerobatic by design so with the thrust of the turbine pushing it at a good clip, some real cool REAALL smooth aerobatics ensued.

Watching an airplane that large knife edge the Triple Tree runway was a hoot. Point rolls, hammer heads, outside loops, like watching a pattern plane with just a bit less roll rate. Fly the final, raise the spoilers touch down and the taxi a sailplane back to the pits. I'm sure the purist sailplaners out there won't go this route, but I think being able to fly those monsters be yourself with no appreciable noise is the way to go!

Next came the Turbo Raven. We've all seen photos of Wayne Handley's Raven and Turbo Raven. I've seen models of both planes, a bunch of them. What I have not seen is a true turbo prop version, let alone a turbo prop even run on a stand! Well kids Eric rolled out his true turbo propped Raven and it was like seeing a new segment of modeling being born.

The plane itself is about 35% (99" span). An all composite bird offered by AirWorld in Germany. It looks to be a true scale outline and the workmanship is of top quality. The swoopy wing and rudder tips are there and scale panel lines and rivets are molded in. The landing gear is carbon, the aluminum spinner came from AirWorld and the overall impression I had on the plane itself was Bitch'en! It simply looks like it means business,it's a mean looking machine.

Equipment consists of JR 8411's and 8611a's with a R2000 receiver. This is one of the new synthesized receivers that range tested out to 140 paces (no antenna with all turbine systems running) One receiver and matched system. I'll be letting the JR pros give you some insight real soon on set ups.

Now for the uber cool part, the power plant. Jet Cat offers the system ready to bolt in. Turbine, WAAAYY cool exhaust pipes, gear reduction, prop adapter, pumps electronics etc. I couldn't resist giving the prop a gentle push as I drooled,, no resistance to speak of. The drive system uses turbine exhaust as opposed to a direct drive system. Much like the way a turbo charger operates. There is a pretty substantial gear reduction (sheesh, do you need to spin a prop at 165,000 rpm?) What this means at the prop is roughly 6,600 rpm on a Mejzlik 27x10 (static). What it spins in the air can only be guessed at, but it will snort when the left thumb pushes the oompah lever.


JetCat lists these specs on the SPT5. Weight 4.9 pounds. 7 ounces per minute at full power. 55 pounds of thrust with 27 inch prop at 7,000 RPM. Maintenance at 25 hours. The system works flawlessly with almost zero vibration. The cool factor is off the hook! I think it could be propped up a bit, but I'm no expert.

50oz of jet- A in the tank, batteries charged, fire extinguisher at the ready and Eric giddy with the coolest new toy in the world, he tightened the canopy and initiated the start. The first thing you notice is the typical turbine spin up, then the real magic happens. You smell kerosene you see a puff of white smoke, then the prop starts to turn ever so slowly. As the exhaust note builds so do the RPM's. After the start sequence is over you can run it up and see what this baby is packin'. It KILLED me to see Eric start to walk down the runway with the antenna out of his 10X. I kept thinking couldn't you PLEASE RUN?? I was dying to see this thing go! Range check was a green light so nothing left to do but fly.

Looked like she did well on the ground. Lined her up, pushed the giddy up stick and off she went. The acceleration was awesome. It was off the ground alarmingly quick and was headed up gathering speed as she went. The sound can't be described. It was quieter than the big electrics I've heard but just has this note like nothing I've heard before. I'm sure you're thinking what about the vert. Biff ? It storms going up hill ! As I watched the bird fly I kept wondering what's going to happen in a tail slide or torque roll?

The first couple of flights included high alpha low speed flights and a bit of trim for knife edge flight. The plane looked solid and not pitchy as one would expect with a scale outline. After 5 or so minutes the turbine slowed and stopped. A non- event deadstick and close inspection revealed a wire (like I could tell you which one! ) came out of the black thinga-ma-jiggy for the turbine control. This was located in the inlet section of the cowl. A quick wire tie and problem solved! All flights after this were perfect operation of the system.


The answer to my tail slide and torque rolls were answered in subsequent flights. No issues with the turbine at all. As Eric got used to the plane he increased flight loads and really checked out the entire envelope. It was pretty much like watching any aerobatic plane fly except my ears kept reminding me this is a new phase of RC flight! A straight low pass with all the coals poured on it will raise the hairs on the back of your neck. The
prop was indicating how much power is being pumped out. Around 8 HP according to JetCat. Knife edge passes are equally cool! This system is sure to be a hit during the noontime demos at the 'Nall.

The spool time on this system is super for a turbine. I asked Eric for a flight report soon after his third flight. His response was "too early, let me get some time here before you quote me." (He was grinning like a mule eating briars!) In an effort to be a gentleman I waited till the end of the 5th flight to approach him with pad and paper."It's different than flying a piston job. You need to stay ahead of the plane with throttle. Landings require careful attention to wind direction and speed as residual thrust even at idle is a bit more than expected.As far as flying the plane, I need to work on a demo sequence that plays into the system. Either that or just get more time and really figure it out!"

The AirWorld Turbo Raven is a real clean design with no speed brake or drag increasing elements to slow the plane. With a turbine powered jet model you are around 50% power on approach with all sorts of drag hanging out, so if you need to go around just clean it up and you have plenty of thrust available quickly. With an aerobatic model you approach at idle, so if you need power to go around you better be early. I watched Eric spool the plane from idle to full, looking at around 5 seconds. Flying the plane with 50% throttle gives you full RPM's around 2 seconds. The plane is easy to fly as long as you stay ahead of the throttle.

Do I think turbo props have a home in aerobatics and 3D ? Yes and no. At present the spool up time is just a bit more than would be acceptable for our needs. Enter the variable pitch prop! Being able to run the turbine at 100% and use pitch to control thrust instantly would make this a very viable option. I've checked with my spies and hear from reliable sources that VP is on the way for this system ! Being as the turbine cools itself as it runs means backwards flight should be attainable. Using the pitch just like a collective on a helicopter means you would have faster thrust response than a piston powered model. Is the little light going blink-blink in your noggin' ??

With all the hubab about noise and our insistence on brute power and total reliability, this system is something to keep an eye on guys. In closing my hat's off to Eric for being kind enough to ask the question only true flying buds do; "here wanna fly it?" Video coming with DOLBY SOUND! Turn up the home theater and get ready boys!

Turbo Biff

www.jetcatusa.com - Jet Cat turbine engines and turbo prop set up
www.horizonhobby.com - info on Jr equipment
www.airworld-usa.com - info on the turbo Raven
www.joenall.com -info on aero tow and all happenings at Triple Tree
www.waynehandley.com- info on the man himself,, great site!




Bob "Biff" Sadler :
Bob "Biff" Sadler, also known as The Mouth of The South is the Co-Editor for The Leading Edge. An accomplished full scale pilot and hobby enthusiast since 1967.
biff@flyinggiants.com
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[Edge540T_Flyer]

Check out the video here!

http://www.airworld-usa.com/Videos/raven%20.wmv

[always flying]

	Quote: Originally Posted by Edge540T_Flyer
	Check out the video here! http://www.airworld-usa.com/Videos/raven%20.wmv

Thx! for the link man!....that was Wicked!!

[Kiwi]

Not only was that wicked but boy sounded expensive as well.

Still it is only spare cash right?????

Mark my words here. The next big OOOOOHHHHHHH to come in 3D is coming from either a turbine or a gas engine equiped with a fully controlled prop. Something like a constant speed unit but it will be able to feather, go beta and of course have a pilot varied pitch off the transmitter.

Then my brothas, we gonna see some new tricks. I think it will be a turbine as it should be easier to do the setup and it will be better for the turbine as well as it will stay at a constant rpm.

When that puppy comes out I WANT ONE!!!!!!..

You wnat me to put you on the list as well JEEUM.

Kiwi

[Boulder]

There is nothing like that sound...I wonder how one of them would do all out 3D. The engine spool up would be quite a bit slower than an IC engine.

[Kiwi]

Ken,

Not with a variable pitch prop. Rather like a turbine heli. The turbine stays at full rpm and only the pitch changes, it would be quicker than a gasser at taking the load I think.

Kiwi

[YNOT]

Eric always has the coolest toys.

[Shortman]

I would like to more know on that set up. Flight time, speed, weight, etc.

[YaKs are BeSt]

I see, variable pitch on a turbine takes away the acceleration issue, the turbine just runs like a lawnmower!!!

[Kiwi]

Perfect explanation.

When they get that sorted the party will start all over again. Not just VPP foamies, 40% airplanes with reverse pitch!!!!!!

Take it away Quique.

Kiwi

[HW123]

That is a Fabulous looking air plane that Eric Meyers has there. Tim Redelman did a fatastic job building it for him. I obsevered Tim's hard work and craftsmanship over a couple months in his basement putting this awsome plane together. Very nice plane Eric.

[HW123]

That is a Fabulous looking air plane that Eric Meyers has there. Tim Redelman did a fatastic job building it for him. I obsevered Tim's hard work and craftsmanship over a couple months in his basement putting this awsome plane together. Very nice plane Eric.