Experimentals

[tradford]

Hey folks, I'm somewhere around half way to my PPL at a local school here in the Atlanta area. Though I'm presently focused on getting to the other side - I can't help but ponder what the future holds for me with respects to flying (for sport). I have no plans to enter the craft commercially, I'm just doing it because it's hard (for me anyway at 60 years old). It's unlikely I'll purchase an R22 or similar, but an experimental (like a Mosquito) is something I could fathom. It looks like a great way towards an affordablem means of flying regularly. It appears to be a growing past time (little solo machines). Any opinions?

[pilot#476398]

If I had the funds I'd buy a helicycle (renting a 22 once a month or so kinda sucks). I don't have any experience with them, but I think the Eagle looks a little better than the Mosquito. Either one looks like a lot of fun to fly though!

 

If you can find them, there are some threads on here from a guy who builds helicycles, that you may find interesting?

[Jaybee]

I plan to buy one the first day I can afford one.

 

The factory test pilot does 30' hover autos with one.

 

They are a solid machine if maintained well.

[Dreamin of a Commuter 2B]

for experimental info, check out www.rotaryforum.com

 

mostly Gyroplanes, but lately been a lot of posts about the MH-1 conversion of the mini 500, and Stan Foster has all kinds of info on his helicycle, you can also find info on the mosquitos on there.

 

I my self am restoring a Very vare 2 place experimental helicopter and just sold the airframe to the single place Helicom Commuter,which is the fore father to the safari kit Helicopter.

 

 

[500E]

Stan will give you all the info on the Helicycle, his is turbine & is superbly finished, as DoAc2 says there is a lot of info on the HC & mini on the site he posted

[avbug]

When the helicycle was under development and later under production in the early stages, I visited BJ Schramm in Idaho at his facilities. Typical for Schramm, he was too busy to stop and talk, though he said I could follow him as he worked and he'd talk. The man was a worker and very dedicated to his projects. In my opinion, he designed and the company produces a very solid project, but like any experimental, what you end up with is largely up to you.

 

You also need to understand that the degree of testing and field proving of the end product is not what you get with a production aircraft, nor is the oversight or regulatory design requirement present. Many experimentals exceed quality and workmanship of production aircraft by virtue of the effort of their builders, but that's very subjective, and there are also many that don't. In the end, unless you have someone like an EAA advisor closely mentoring you, the person looking over your shoulder while you work is you.

[tradford]

I think that a solo experimental bird is about the only option available to me if I want to fly with any frequency post license. I've been getting some stick time in an R44 at R22 rates and I have to say that it's a dream to fly (compared to the 22). But either one is prohibitively expensive to rent and even with a partner to share ownership of a used 22 with 600-800 hours left - it's still a bit beyond my means. Dropping $60K or so on a turbine powered Mosquito is a possibility. Anyone have any data as to the reliability of a turbine when compared to a piston engine? It's worth an extra ten grand just for the sound!

[MileHi480B]

The Mosquito, Helicycle, Safari, Rotorway and Hummingbird are all great machines if built and maintained properly. Most, in my opinion, are NOT. Either do it yourself or find someone you trust enough to put your life in their hands.

[avbug]

Anyone have any data as to the reliability of a turbine when compared to a piston engine? It's worth an extra ten grand just for the sound!

 

 

When you ask about turbines, you need to qualify your question. Certificated turbines, built for the purpose of powering an aircraft in flight, are one thing, when maintained properly. The helicycle doesn't use such an engine. It uses an APU turbine that was designed to run a generator, not provide propulsion or lift to an aircraft. Imagine your lawnmower being drafted into an entirely different role, and you're getting closer to the idea.

 

This isn't to say that the powerplants aren't reliable. Sunstrand and other APU motors have proven quite reliable, but I've seen a LOT of cases where they shut down during operation, too, for a host of reasons. From my perspective as a mechanic, pilot, and instructor, I'll say that for the most part, turbines are a lot more reliable than piston equipment, but when I say that I'm referring to purpose-built and designed turbines, not re-purposed turbine equipment. Your saving grace as a helicopter pilot is that unlike a fixed wing aircraft, you can autorotate.

 

Keep in mind that in a small helicopter like the helicycle, you've got a very short fuel supply and a very high fuel consumption, so practical uses are limited. It's still a very cool machine, but understand that it's far, far from an apples to apples comparison against a type certificated machine.

[Jaybee]

I find that a funny analogy since the Turboshaft engines used to power certificated helicopter rotors were adapted from and commonly used as APUs in large Turbofan aircraft

[aeroscout]

Comparable fixed wing aircraft have a much higher power off glide ratio than helicopters.

[avbug]

I find that a funny analogy since the Turboshaft engines used to power certificated helicopter rotors were adapted from and commonly used as APUs in large Turbofan aircraft

 

 

Turbine engines powering helicopters are, regardless of their original source of development, NOT APU engines. They are type certificated engines that are primary powerplants.

 

The TFE-331 that powers many light business jets such as the Lear 35, Falcon, and others once had origins in an APU turbine, but the TFE-731 is most definitely NOT an APU. Likewise, whether you're talking about a Lycoming or Pratt or Turbomecca or C250, it's what's powering a modern production helicopter is NOT an APU.

 

You could try to take the analogy even further into the mud by suggesting that piston engines in piston helicopters came from piston engines in cars…but the piston engine in an Robinson or Schweitzer isn't an automotive engine.

 

The powerplant for the Helicycle IS an APU motor, straight out of the back end or side of an aircraft and using a few components from Helicycle, has become their powerplant. That APU was never intended for that role. To make a comparison between the APU engine in the Helicycle and the powerplant in any type certificated helicopter is ridiculous. They're both turbines, but that's about it.

[tradford]

Thanks guys. All I know is that a few of the kit helicopters are available with some form of piston engine (two or three cylinder two stroke) or a turbine powerplant. I'm of the opinion that two stroke engines can be pretty reliable over the long based on my ownership of two stroke motorcycles back in the day. I don't think that the turbine kits have been flying long enough to have accrued a sufficient amount of failure history. Hard to make a call without some statistical data to support one decision or the other. I did visit the site of the folks that provide the Solar turbine used on the Helicycle. Very interesting.

 

www.aviomania.com/T-62page.htm

[adam32]

 

 

 

You could try to take the analogy even further into the mud by suggesting that piston engines in piston helicopters came from piston engines in cars…but the piston engine in an Robinson or Schweitzer isn't an automotive engine.

 

 

 

You're right, the piston engine in the Robbie or Schweitzer is about 30 years BEHIND in technology compared to the piston engine in your little Honda Accord...same with Turbines, not much has changed on them in 50 years.

 

What's the most reliable turbine ever built?

Edited December 3, 2013 by adam32

[500E]

Thereare a few hellicycles with over the 1000 hours I think

[avbug]

You're right, the piston engine in the Robbie or Schweitzer is about 30 years BEHIND in technology compared to the piston engine in your little Honda Accord...same with Turbines, not much has changed on them in 50 years.

 

Your Honda Accord is type certificated for use in aircraft? Get it that way, spend the millions of dollars necessary to do so, then check back.

 

There's a reason that Frank Robinson didn't yank the engine out of a Honda Accord to stick in the R22.

 

A LOT ha s changed with turbines in the last 50 years. Apparently you don't have any maintenance experience dealing with turbines. Especially turbines over the years. I gather you don't have much experience with operating a wide range of turbine engines over the years, either. Ive operated ones designed to run on avgas through some very new types, from small to very large ones.

 

What's the most reliable turbine ever built?

 

Reliable in what respect?

 

Mean time between failures? Durability between overhauls? Maximum continuous time in operation?

 

You'll find some turbine engines have been run for a number of years without shutting down; that's continuous operation. That may sound reliable, but it's one cycle as far as the engine is concerned. Of greater interest are engines operated with a number of thermal cycles. The primary enemy of turbine engines is heat. Thermal damage during engine-start is one common source of heat damage, but overtemp during operation, or frequent operations can also lead to reduced life or failure.

 

I had the misfortune of being on a scaffold close to a T-62 that went ballistic on a test stand a few years ago. I thought it was going to come apart. It was spraying fire and making an ungodly sound. Some brave soul managed to get close enough to shut off the fuel supply before it grenaded, but I'd hate to have been there when it did.

 

The T-62 in the helicycle is derated. It's not working as hard as it does in normal operation at 100% (103%), but in normal operation it isn't subject to the types of cycles that it gets in the experimental helicopter role. It should be noted that although it is derated in the helicycle, it's also subject to more abuse. It should also be noted that APU's in aircraft aren't noted for their exceptional reliability, either. I've operated a lot of T-62's in their role as an APU over the years, and long ago I lost track of the number of hung starts, failure to start, or automatic shutdowns that occurred. In all fairness to the T-62, a number of those occurred with cold-soaked engines after long exposures to very low temperatures at high altitudes.

 

Remember with the helicyle that you always have the option to autorotate. Not quite as good as pulling the family sedan over to the side of the road when the engine falters, but close enough. Fixed wing flyers should be so lucky.

[adam32]

Your Honda Accord is type certificated for use in aircraft? Get it that way, spend the millions of dollars necessary to do so, then check back.

 

There's a reason that Frank Robinson didn't yank the engine out of a Honda Accord to stick in the R22.

 

 

 

The reason and only reason is because he didn't want to spend the money! Has nothing to do with what would be the better engine, and remember that was in the 70's also. What has changed on the Robbie engine since it was first released?

 

As far as turbines, no not much has changed, the basics are still the same since the 50's. A lot of helicopters flying today were designed in the 60's/70's and built in the 70's/80's. The experimental guys are far ahead in technology compared to certified aircraft and that's a fact, Jack!

 

The most reliable turbine is the Astazou series, designed in the 50's.

[Jaybee]

Big sigh... all I said was I thought it was funny. FUNNY.

 

I didn't say your were wrong or right or left. No need to bow your chest out and start thumping because guess what - its called an opinion. I have one you have one, Arthur Bell had one, Igor Sikorski had one Frank Robinson had one. Guess what they are ALL valid. So please spare me your lectures, I didn't drag anything into the dirt (paranoid much?)

 

FACT - turboshafts were adapted from APU service and put to use in rotorcraft.

 

As long as the adaption was done correctly that is all that matters. You logic about them being designed for APU service is what they call a red herring or false flag argument. Its akin to the redneck at Autozone stating his Ford runs best with Motorcraft spark plugs. The spark plugs don't know what engine they are put in, the engine don't know what spark plugs are in it - its not a Disney story with dancing spark plugs. Right heat range, right reach and good quality is all that matters. At the end of the day the turboshaft engine doesn't know or care if it is pulling APU duty or powering a hamster wheel for that matter.

 

Properly adapted is all that matters.

[apiaguy]

I'm always a rotocraft proponent of an older Hughes 269, Hiller, Enstrom, Bell 47 etc... Way before building or buying experimental... my reasons... usually with the lack of serviceability and history of experimental rotorcraft not holding value or holding together. Unless you have aviation maintenance background your really tinkering with your life... I know, guys do it all the time... just putting my reservations out there for you. You could easily buy one of the above named machines for the price of a helicycle... fly it... take passengers and sell it for close to what you paid years later... of course you have to maintain it... and that does cost.

[Guest pokey]

as my 60 year old A&P instructor told me when I was a young lad of 30 in his FAA certified A&P school "certificated mechanics do NOT work on homebuilts"

 

I never did, never will

[avbug]

As long as the adaption was done correctly that is all that matters. You logic about them being designed for APU service is what they call a red herring or false flag argument. Its akin to the redneck at Autozone stating his Ford runs best with Motorcraft spark plugs. The spark plugs don't know what engine they are put in, the engine don't know what spark plugs are in it - its not a Disney story with dancing spark plugs. Right heat range, right reach and good quality is all that matters. At the end of the day the turboshaft engine doesn't know or care if it is pulling APU duty or powering a hamster wheel for that matter.

 

 

Now THAT would be the false-flag argument. No, popping an APU into an aircraft isn't at all like changing a spark plug. Not in the least.

 

Engines and spark plugs don't know anything. They're not sentient. The person putting them in does, though.

 

A hamster wheel in a helicopter doesn't work; it's not the right part. It's not an engine. A turbine engine in a helicopter does work, but only if it's the right engine in the right helicopter. You're not going to have a lot of success pulling the engine from one type of helicopter and putting it into another different type. The engine doesn't know, doesn't care, but it doesn't necessarily fit, doesn't mate up. Adaptions to other powerplants take engineering and money, to say nothing of testing and development. Putting dual Pratts in a UH-1 isn't anything like installing an APU out of the back of a DC-10 into a homebuilt helicopter. Don't try to compare it to changing a spark plug.

 

FACT - turboshafts were adapted from APU service and put to use in rotorcraft.

 

 

You keep using that word: adapted. In fact, the APU was the beginning of a concept from which an engine was developed, but it wasn't simply adapted into an aircraft from an APU installation. Not in the least.

 

The Eagle R&D powerplant, however, really is a T-62 that's been plucked out of an aircraft, and installed in the helicopter. Not at all the same thing as a type certificated, proven, tested, and certified engine installed in a production helicopter. Opinion, be it Sikorski's or Robinson's doesn't change the fact. The Helicycle uses an APU for a powerplant. Production aircraft do NOT.

 

As for your ultimate "red herring argument," most certainly a discussion about the differences between plopping an APU, borrowed out of a fixed wing aircraft, into an experimental helicopter vs. a type certificated dedicated turbine engine in a production helicopter is not remotely akin to a redneck commenting on spark plugs in his engine.

 

As far as turbines, no not much has changed, the basics are still the same since the 50's. A lot of helicopters flying today were designed in the 60's/70's and built in the 70's/80's. The experimental guys are far ahead in technology compared to certified aircraft and that's a fact, Jack!

 

No jack, when considering the APU base powerpplant put into an experimental helicopter, that's not at all a fact. It's definitely NOT far ahead in technology, and yes, a LOT has changed since the 1950's. The turbine's still spin, but that's about it.

[Nearly Retired]

The Solar T62 turbine engine might seem like a perfect candidate for a small homebuilt helicopter, but it has some...shall we say, "issues."

 

For one thing, The T62 is a fixed-shaft turbine. Fixed-shaft turbines have ZERO place in a helicopter (other than as an APU). Some early turbine designs (mostly French) used a fixed-shaft turbine. And I don't know if any of you have noticed or not, but *NO* current airframe manufacturer specifies fixed-shaft turbines in any of their modern designs.

 

Secondly, a fixed-shaft turbine must have a clutch, since you cannot get the N1 (compressor/gas generator) spinning up first, while letting the N2 power turbine (and output driveshaft) "catch up" at its leisure. The compressor and turbine are all on one "fixed" shaft. Since a clutch isn't part of the Solar design, YOU will have to deal with that.

 

Thirdly, the output shaft rpm of the "-2A" version that comes out of a Chinook is 6,000 rpm. The "-16A" version that comes out of the Skycrane has an output shaft rpm of 8,000! So a separate reduction gearbox of some sort must be designed...OR...your main transmission must be designed in such a way that it can accept 6 or 8,000 rpm input. Holy cow!

 

Solars have no electric starter. They are usually started by a hydraulically run pump. So you'll need an electrically driven hydraulic pressure pump, and another one (slave) to spin the engine. The hydraulic pump spins the engine up to 90% rpm before it's self-sustaining, so it's not like you can just jury rig a pull starter like on your lawnmower.

 

Oh, and you want an alternator with that? Well, you took that part off to get access to the output drive shaft, so now you'll have to either devise an alternator that can run at 6 or 8,000 rpm. OR mount one somehow to your main transmission. That should be fun. Maybe take power via a belt off the tail rotor drive shaft.

 

Although the Solar T62 does have a "governor" of sorts, it is designed only to handle the varying electrical loads of the alternator it usually drives, *not* the varying loads and rpm of a helicopter rotor. And since turbines have much too much "lag" in their throttle response to be hand-controlled, a good governor is a must. In addition, a mechanical droop-compensator of some sort must also be designed

 

While you're at it, you should know that the Solar has a built-in device that shuts the fuel OFF if the engine speed exceeds 110% rpm...OR...if the switch senses an overtemperature. Shuts the fuel off. Which means that for all intents and purposes there's no getting it back while you're in the air. You're going to the ground.

 

Overtemp? Well, the Solar has a maximum thermal limit of 1090 degrees F, which translates to about 588 Celsius. Seems pretty low to me. The RR 250 C-20B engine has a max-continuous thermal limit of 810 degrees Celsius and can run there all day long. Let me say that I have no knowlege of any helicopters powered by a Solar turbine, but I'd imagine that in such an application they run pretty close to their thermal limit most of the time. I mean, come on, the biggest Solar is only 150 h.p., and that ain't the one that came out of the Chinook.

 

That's not to say it's impossible to adapt a Solar turbine to a helicopter. Obviously it's been done. But the engineering and operational challenges are considerable...perhaps far above the level of the home builder. It's an interesting design experiment, but that's all it is. The thing is just not practical.

 

I would bet that those who have "successfully" installed a Solar in their helicopter will downplay the challenge and effort it took, especially if they're trying to get you to buy their kit.

[pilot#476398]

So then,....get the piston engine version of that mosquito?

[apiaguy]

I think... while the mosquito, helicycle, jet exec, all look really cool and would be fun to tinker with... the thought that you can buy one of these, spend the time to build it and then fly any time you like is a fantasy. If you are in it for the pilot time and hours and not just an adventure in life... go with one of the ones I stated earlier.

 

On apu turbines, experimentals in general and the "technology" between certified and experimental...

 

experimentals are fun and should be fun because the freedom to do what you like without regulation... it works quite well in the fixed wing world because the airframe design is typically the only thing experimental. VERY few people use an engine that was not intended for aviation use... hmm, wonder why? Why add complexity and unknowns to the equation? Do you really think that honda civic engine would make a good aviation engine? Or is the technology used in it really that much better than what we currently have? What are we looking for that we don't currently have?

Would multi-port electronic fuel injection make a real difference? Everything is a compromise.

Do we need better specific fuel consumption? Better turn key start function? Less pilot monitoring? All of these questions could be answered yes and no...

When it comes to the "hobby" of flying helicopters, I see very little true success in experimental rotory wing flight... mostly due to costs, time required and the realization later that is isn't what they thought (the fantasy idea). If you want to fly helicopters and not "play with them" (or experiment) I would again suggest you look at one of the used certified machines. Get to know the designs, get to know the people that operate those older designs... you'll be suprised how small a world it is and everybody is usually very willing to help you make a decision that would support your dreams, provide technical support, used parts, etc..

 

The apu thing... I want to put two solar's together thru a combined reduction drive unit and mount it in one of the extra 269 airframes I have... Twin turbine time baby!!

[Spike]

I tend to stay away from flying machines that do not have an airworthiness certificate. Then again, I fly for a living so my perspective is somewhat jaded. Either way, if the joy of recreational flying is so strong, I’d stick to stick controlled single engine tail dragger airplane. Cheap (relatively speaking), reliable, safe, and certificated with less exposure to liability…….