Engines For Ultralights

[GyroJoe]

Hello Friends,

I'm getting fatter surfing the web! I've spent hours all over the
internet, as well as this forum, looking for every engine applicable
for an ultralight gyro. Would you fellow gyrothusiasts be so kind as
to list the engines suitable for tractor-type configuration. I would also
like to know the horsepower ranges, as well as opinions on max.
engine weight.

This list would be very useful for those wanting to build a
pusher/tractor ultralight.

Thank You,
Joe

 

[GyroJoe]

1/2 VW Engine

1/2 VW Engine

Are the 1/2 VW engines too heavy?
Is the horsepower suitable?

Thank You,
Joe

 

[GyroJoe]

Hirth F23

Hirth F23

Hirth F23
Tractor
45 HP
78 lbs.

From: gyromaxwell's current gyro

 

[GyroJoe]

Hummel's 1/2 VW

Hummel's 1/2 VW

1/2 VW
Tractor
45 HP @ 3400 rpm
79 lbs.

From: Hummel Engines

(thumbs up or down?)

Joe

 

[GyroJoe]

Other Engines, No Specs Yet

Other Engines, No Specs Yet

Other engines I've come across on the web,
but don't have the weight and HP yet:

Rotax 447 & 503
Hirth 2704 & 2706
2si-460F, 40 hp? (I read about the lawsuit and the
unavailability)

I'm still surfin'.

Joe

 

[GyroRon]

I don't think the Hirth is going to do the job, we will see how gyromaxwell's does, but I will not be surprised if he finds it too underpowered to get out of ground effect.

The VW won't take the stress of running wide open as it would have to in any gyro. The full four cylinder VW's are just enough power, the two cylinder I don't think would get even the lightest gyro in the air.

The Bigger Hirths would work along with my favorites the Rotax 447 and 503. The 2si is not known to be a reliable engine, and I think they aren't selling them anymore anyhow.

 

[GyroJoe]

Four Stroke

Four Stroke

Thanks Ron, we appreciate your input.

Let's say some of us are partial to 4-strokes:

1) What's the "minimum" horsepower?

2) What's the maximum weight?

Guys, please include engine weights and horsepower
so we can have reference points.

Are the 4-cyl VW too heavy?

What about HKS?

Back to the web....

Joe

 

[GyroRon]

there just isn't a light enough airframe to allow the use of a heavy four stroke and still be a legal ultralight. On some fixed wings they claim to be legal ultralights using the half vw but I am doubtful that they really are legal - as in light enough.

The half vws make just enough power to fly a small fixed wing, but just barely. They just wouldn't make enough power or last long pushing a gyro around. Maybe if you only weighted 100 pounds and your airframe was VERY light, it might do the job but probably not.

The HKS would be great. It is a nice engine and isn't too heavy and would make enough power for a reasonably light single place gyro. It is very expensive though. It is a four stroke, but it turns the same rpms as a two stroke to make its power. It has alot more moving parts than a two stroke and turns just as fast, and since it only makes power on every other revolution of crank it is in effect much more stressed than a comparable two stroke.

The HKS is 600 cubic centimeters and the Rotax 582 is roughly 582 cubic centimeters. Both make about the same horsepower, but the difference is the Rotax is DE-tuned and the HKS is more or less pumped up. The HKS does have a good reputation in the field as being dependable and going to TBO without much trouble. I would have one if I were able to get by with only 60 horsepower.

 

[gyroblackwell]

Hirth underpowered?

Hirth underpowered?

Hay now lets just wait one darn minute here! The 447 puts out 40-42 hp
and it will get ralph up and away .....the hirth F23 puts out 45 hp, and weighs less then the 447 complete !

besides, I'm running in tractor mode ...... clean air, and a 60" prop to boot !

O.K. .... I guess we will just have to wait and see now won't we !

keep that up ron, and I won't let you fly my machine ! AND I'll take my toys and go home !!

 

[GyroRon]

Remember a ultralight can't weight over 254 pounds ready to fly minus gas and oil. The lightest gyros out there are going to weight close to 150 pounds minus engine ready to fly and that is stripped down to bare bones, no instruments or anything. the lightest four cylinder engines powerful enough to fly a gyro is a Jabiru 2200 which retails for around 10 grand. It weights around 120-130 pounds ready to fly I believe.

the VW four cylinders are going to weight at least 160-180 pounds ready to fly.

the subaru EA-71 or EA-81 is going to be at least 200 pounds ready to fly with coolant.

So four strokes are pretty much a no go on a ultralight gyro. Unless you build a stock stripped gyrobee and use a HKS or Jabiru...... and even then your VERY likely to run over the 254 pound weight limit.

Any gyro, the rule of thumb is you want half as much thrust as your all up flying weight. If your gyro weights 600 pounds with you in the seat and fuel and so on, you need 300 pounds of thrust to safely fly. From first hand experience I can tell you that a Subaru EA-81 with direct drive, or a 1835 VW direct drive both put out right at 300 pounds of thrust. The Rotax 503 puts out around 275-280 pounds of thrust and it weights considerably less than the four strokes. The rotax 582 puts out between 325 and 360 pounds and only weights a tad more than the 503.

Thrust is what counts not horsepower. The 52 horsepower Rotax 503 nearly equals the thrust output of the 65 -70 horsepower VW and 70-78 horsepower Subaru.

 

[GyroRon]

Hay now lets just wait one darn minute here! The 447 puts out 40-42 hp
and it will get ralph up and away .....the hirth F23 puts out 45 hp, and weighs less then the 447 complete !

besides, I'm running in tractor mode ...... clean air, and a 60" prop to boot !

O.K. .... I guess we will just have to wait and see now won't we !

keep that up ron, and I won't let you fly my machine ! AND I'll take my toys and go home !!

Tim if you had a Rotax 503 up front I would feel much better about it getitng airborne!

The MZ 201 that Dana at Starbee has on his bee wouldn't really make enough power to get me out of ground effect. That was supposed to be 45 horsepower and lighter than a Rotax 447......

The biggest weird factor that has me scratching my head is the fact that both tractor gyros I have flown were really WAY underpowered. Joes JT-2 ran out of climb power and the engine got dangerously hot at about 200 feet. It took full throttle just to stay in the air. Johns Pitbull was the same thing. Both gyros had engines that were reasonably powerful with reduction units and much bigger props than usually found on pushers. I am sure that if those engines were mounted as they were on a pusher they would have been powerhouses. Just makes me wonder why.....

No hard feelings though, I really hope the little Hirth works out. I hope to see it and perhaps fly it one day.

 

[GyroJoe]

Okay, Thrust Rather Than HP

Okay, Thrust Rather Than HP

So,

Tim says he expects his Jryo Dear to weigh in at 200#.

Think I could put an HKS on it, if I wanted to spend the
extra money?

Joe

 

[GyroJoe]

Hypothetical Ultralight Thrust Requirements

Hypothetical Ultralight Thrust Requirements

Any gyro, the rule of thumb is you want half as much thrust as your all up flying weight. If your gyro weights 600 pounds with you in the seat and fuel and so on, you need 300 pounds of thrust to safely fly.

Thrust is what counts not horsepower.

254#..........gyro wt.
180#..........pilot wt.(that includes his underwear and helmet)
36#.........fuel wt. (so the sum will round out)
-----
470#..........total wt.

Say with a 210# pilot (after the Thankgiving and Christmas all-
you-can-eat buffet), we'll make it an even 500#.

We'll need an engine with 250# minimum thrust, correct?

Inch by inch, it's a cinch........

Thank Ya'll,
Joe

 

[GyroRon]

So,

Tim says he expects his Jryo Dear to weigh in at 200#.

Think I could put an HKS on it, if I wanted to spend the
extra money?

Joe

Tim is making a one of a kind gyro, wait and watch and see how much it weights when he is done. I am very curious how much it will weight when it is done.

 

[gyroblackwell]

HKS motor

HKS motor

I love the HKS motor. I flew a 2-place flightstar with this motor. Man what-a-ride. The power is Awsome, and knowing that the motor is not going to just up-and-quit on you is a great comfort. Not saying that I have had Engine-out problems, but I have lost power once, and spent 6 months repairing my plane after a Horse pasture landing, with a near miss with a racing horse and subsequent stalled landing.

Ron - I think that the previous craft you flew all had OTHER problems. The Star-Bee would have flown with the right prop installed. I looked at the setup, and using a cheap prop with-out enough RIGID pitch will not get you anywhere. That prop flexes to a flat pitch under load.

The Pitbull aircraft is just too heavy with that fiberglass(or was it kevlar?)
body on it.

Also check out the Dia. of prop they are using.

Long term.... it is my goal to prove that a tractor design (not the one I am building right now) can be flown on 35-38 hp !


Proof is in the pudding !!

 

[GyroRon]

I love the HKS motor. I flew a 2-place flightstar with this motor. Man what-a-ride. The power is Awsome, and knowing that the motor is not going to just up-and-quit on you is a great comfort. Not saying that I have had Engine-out problems, but I have lost power once, and spent 6 months repairing my plane after a Horse pasture landing, with a near miss with a racing horse and subsequent stalled landing.

Ron - I think that the previous craft you flew all had OTHER problems. The Star-Bee would have flown with the right prop installed. I looked at the setup, and using a cheap prop with-out enough RIGID pitch will not get you anywhere. That prop flexes to a flat pitch under load.

The Pitbull aircraft is just too heavy with that fiberglass(or was it kevlar?)
body on it.

Also check out the Dia. of prop they are using.

Long term.... it is my goal to prove that a tractor design (not the one I am building right now) can be flown on 35-38 hp !


Proof is in the pudding !!

Tim, I do not agree - go figure right! - about some of your points.

First off, the HKS like most converted auto engines used in aviation is likely to quit all at once out of the blue if something goes wrong.... Just like a Two stroke. Sure it has dual ignition so if one side failed the other igntion could keep it running, and maybe if one of the carbs broke, the other carb would at least give you half power and maybe allow you time to pick a nice landing spot. BUT my opinion is that if something inside breaks or is about to break, there will be little warning and pretty much no limp home mode, due to the engines high state of tune and the Rpms it is run at.

Saying that, I myself would feel safer flying the HKS over my Rotax, but I wouldn't treat it as if it were a Lycoming. I would still have a place to land under me at all times. And I wouldn't be flying with the assumtion that if something starts to go wrong I might be able to limp home, as some planes with Lycomings do, or your car or truck might do on the drive home. I have had Subarus fail and they usually just quit. Sometimes they give some warning, but rarely do they limp back to home.

Two strokes give warnings too if your monitoring the temps. That is what is nice about the EIS instrument system. If a temp exceeds a pre set limit, the screen flashes to grab your attention so you can prepare for a landing or make adjustments, etc....

 

[GyroRon]

Also the Pit Bull I flew, had the fiberglass pod removed. It was just a bare bones frame with a engine out front. It had a Subaru EA-81 with a rotax C box with a 2.67 to 1 ratio and it turned a Powerfin prop over 72 inches in diameter.

The JT-2 had a 2180 cc VW with a belt reduction and it turned a prop that was getting close to 80 inches in diameter.

The Starbee machine may have had the wrong prop, but I know alot of people running that prop on ultralight airplanes and gyros and although it is known to be a crappy prop, it is working to get those people in the air and flying. Chris CLS447 has that same prop on his Rotax 447 powered Aircommand and it flys him around fine. Tim Barnstormer has that prop on his 447 Aircommand and it also flys him around..... I think the engine is just too weak. I advised Dana to change out to dual carbs and turn the higher Rpms to make it into a MZ-202 which makes considerable more power. Not sure what he did. I will agree though that his machine might have gotten out of Ground effect with a better prop, but I think it would have still been way underpowered still.

 

[gyroblackwell]

OK Ron- we agree to diagree. My comment was based on the fact that the HKS is a 4-stroke two cylinder motor that does not have to run at the RPM's that the 503 does when mounted on the flightstar 2 seater.

No .... I never fly over anything I can't land on or in. And as I stated in my post... when the motor cut to idle in my flightstar, I was not going to limp back to the airstrip... I put it down where I had too!

Yes Instruments are everthing in an ultralight ..... not a place to skimp!

I want to mount one of those EIS systems on the jyro-deer.... when I get to that point ! It will also help keep things light !

I hope I can prove you wrong on the Hirth. People give the Engine a bad rap without ever trying it. The F23 is different from the standard line Hirth motors, and I hope it does not let me down. That being said, I origonally designed the Jyor-Deer with the 503 as the motor, so I have one sitting on my workbench ready to go if I need it! I also have the motor-mount, and composite tubes ready to switch out if need be !

Nothins keeping me grounded except murphy's Law !!

 

[GyroRon]

I am not saying the Hirth is bad! Just curious if it will live up to what they say it should do. tie that thing to a scale and pull on it Tim. what kind of static thrust can you get out of her?

What kind of Rpms did the HKS turn on the flightstar you flew? All the ones I have seen turn over 5000 Rpms in level flight and close to the same Rpms at full power as the two strokes. The 503 Rotax is not really enough engine for a two place flightstar so you got to work it hard to do the job. A 582 would be just right for one.

 

[gyroblackwell]

Ron- I know you didn't SAY that the Hirth is bad ..... but .... I could feel you leaning that way .....O.K. skip that part.

I will subject the Jyro-Deer to the pull test at one of the Fly-Ins this summer !

At cruise the flightstar was showing 3750 on the RPM's
At full power she was just under 5000. It's the cruise that I liked. And have you heard of any Engine-outs of an HKS yet?

Flightstar uses the 503 with Fan and belt removed, and a cooling shroud placed around the cylinders. (remember the flightstar is a tractor with the Engine above the cockpit in free-moving air)

Anyway ..... I agree that the MZ motor is under-powering a gyrobee

Nuff Said !