ROTAX! 447 vs 503

[nsheryka]

Ok, I have been debating this question for months now and cannot make up my mind. Every time I think I have found the answer to my gyrobee problem, someone gives me some really good reasons to go the other way than I was thinking.

The question is, should I use a Rotax 447 for my bee, or a 503? I am 155 lbs, and live in Rhode Island (low altitude).

The designer of the bee, Ralph Taggart used a 447 in his original design, and boasted that it was plenty of power. However it seams that he is using a 503 in his remake of the original.

Doug Riley told me that I would be fine with the power that the 447 produces, however other people I talk to advise me to not even think about the 447 and go with a 503.

Price is not that big a deal, when spending 3 grand on a new engine what is 400 more bux or so?

I would really appreciate some feedback from anyone who has any experience with either engine, or the gyrobee.

Thanks

[Brian Jackson]

Hi Nick.
I'm wondering the same thing myself... My concern is if the 503 would put me over the UL weight limit. I'm building the GyroBee stock to prints, but would be adding a prerotator. I'm told that that's right on the edge of the max. UL weight. How close I'm not sure. So if the 503 weighs substantially more than the 447 it won't be a choice with me.

[Ralph]

Nick,

Opinions are easy to find. The trouble is, most pilots you ask know nothing about the Gyrobee or its flight characteristics. The average "gyro guy" will always advocate the bigger of ANY two engine options! Doug does know what he is talking about because he has his own Bee and has put in lots of flight time. Flying in Rhode Island at 155 pounds you should definitely use a 447. A 503 is more power than you will need for safe and enjoyable recreational flying.

Anyone wanting to know why I am using a 503 on the new machine, should ask rather than make assumptions that a 447 isn't enough engine. We happen to have a low-time 503 sitting on a trike that we do not intend to fly. Since the engine is there, we will use it. If it was a 447 we would also use it. If the engine were any larger than a 503 we would sell it and buy a new 447! I say that despite the fact that Don is now over 200 and I hit 220 pounds!

Ralph

[nsheryka]

Nick,

Opinions are easy to find. The trouble is, most pilots you ask know nothing about the Gyrobee or its flight characteristics. The average "gyro guy" will always advocate the bigger of ANY two engine options! Doug does know what he is talking about because he has his own Bee and has put in lots of flight time. Flying in Rhode Island at 155 pounds you should definitely use a 447. A 503 is more power than you will need for safe and enjoyable recreational flying.

Anyone wanting to know why I am using a 503 on the new machine, should ask rather than make assumptions that a 447 isn't enough engine. We happen to have a low-time 503 sitting on a trike that we do not intend to fly. Since the engine is there, we will use it. If it was a 447 we would also use it. If the engine were any larger than a 503 we would sell it and buy a new 447! I say that despite the fact that Don is now over 200 and I hit 220 pounds!

Ralph


Thanks Ralph, i think i will take your advice on this one. I guess i just needed to hear it from the gyrobee master himself!

btw, by the end of the summer i should hopefully have some of the framework done on my bee, as well as a website documenting my work up and running. I will give you the link when it works.

The 3d rendering on the SolidWorks model is also nearing compleation and i will sent you some good images and maybe some mpg files of the model as soon as possible.

[Ralph]

That would be great Nick. I think the Solidworks and various 3D rendering options will make it esier for the average person to understand the documentation.

Ralph

[MattPearson]

A couple of weeks ago, I test flew one of our club member's ( Texas Rotorcraft Association) gyrobee's with a 447 and the prescribed two blade Tennesee Prop and it flew really good. I weigh 200 lbs and he weighs 160, so the performance will automatically be better. I flew it with 24 ft Rotorhawk blades, so using the prescribed 25 ftrs would be even better.

[nsheryka]

A couple of weeks ago, I test flew one of our club member's ( Texas Rotorcraft Association) gyrobee's with a 447 and the prescribed two blade Tennesee Prop and it flew really good. I weigh 200 lbs and he weighs 160, so the performance will automatically be better. I flew it with 24 ft Rotorhawk blades, so using the prescribed 25 ftrs would be even better.

thanks for the feedback.

I assume there will always be some top guns out there who will recomend a larger engine, however i would like to stay as safe as possible with my first gyro.

[gyroblackwell]

Hay Brian,

Glad to see you are building a BEE ! I live close, so if you need a hand or an extra par of eyes to figure something out just ask! Buy the way .... would you be interested in bringing your build to ASC nationals at three-rivers to display? I am going to haul my build up there. The nationals are in Sept. Let me know if you need anything!

Tim

[GyroRon]

I have flown this award winning bee quite a bit. Matter of fact I am the only one who has flown this bee! Anyway in these pics it had a 447 on it but it now has a 503 on it. The 447 did just fine, but we were having some trouble with it running too hot - not cause it was a 447, just cause THAT 447 was old and tired I guess. I found a great deal on a used 503 and passed the deal onto Barry and he put it on the bee. I just test flew it a week ago and it flew a little better than with the 447 but not as much better as I thought it would.

I weight between 200-215 depending on how many double cheeseburgers I ate that day, and it flew just great with the 447. Now if this gyro had a pre rotator and a huge instrument pod and alot of other stuff the 503 might be the way to go, but even with all of this stuff, you weight alot less than me and would still get good performance out of the 447.

BUT.......... I would still go with the 503 and let me tell you why. The 503 has dual ignition and the 447 doesn't. The 503 isn't that much more to buy over the 447. The 503 will likely give your gyro a higher resale value since some of the possible buyers might demand the extra power. Also the 447 is a great engine, but the 503 has a reputation as being nearly bullet proof.

So I will say that the 447 is going to be just fine for you, but I think in the greater scheme of things, the 503 is the better buy. The fact it has more power is a side bonus

[Brian Jackson]

Hi Tim.
Reading your profile it sounds like we have much in common. Thanks for the offer in assisting me with my GyroBee project. As far as hauling it, that's the easy part... currently there's nothing to haul. It's "vaporware" at the moment. I do plan to be at the fly-in in Three Rivers on Labor Day though. Ralph Taggart is going to Bee there as well! Right now I'm just trying to scrounge up the cash to get some raw materials together. Until then I'm in limbo.

You can call my cell at 269-357-1959 if you'd like to get together. Drilling & deburring techniques I'd be most interested in practicing.

Regards,
Brian Jackson

[GyroRon]

One thing I would do to a gyrobee If I built one is shorten the width of the landing gear. built per plans you have to have a extremely wide trailer to haul it on.

[Dean_Dolph]

Ron, if someone has a picture of the Star Bee factory machine to post, you will see their 5 1/2 foot landing gear with suspension. I haven't checked their web site since returning from Mentone but supposedly the suspension info is there.

I think Brian was asking about the merits of the original landing gear specs in another thread and the understanding is that the ground handling for a newbee is enhanced. John Landry is/has reduced his.

It is not a Gyro Bee but an example of the ultimate reduction in gear width is Dave Prater's Bensen!

[Brian Jackson]

Here (http://www.rotopix.com/misc/starbee.qtl) is a spherical image of the StarBee gyro, taken from near the pilot's seat. If you click & drag the image around you can see the main gear behind the pilot's seat behind you. The gear stanse is significantly less than what's called out on Ralph's plans. It's a very nice system, but as a newbee pilot I'd rather start out with the wider gear.

You'll need the free QuickTime viewer to see the image. You can get it HERE (http://www.apple.com/quicktime/download/).

Thanks to Dana & Laura at StarBee for letting me take this shot... now I can sell it to the Russians! :eek:

Cheers,
Brian Jackson

[johnmini]

Guys, I am building a Star-Bee with the new shorter axel,will post pictures soon. Ron, when are you coming up? John

[Ralph]

The StarBee narrow gear option is convenient and nicely done. However, for a first-time pilot, you are well advised to build the gear stock. It was designed to minimize the chance of dumping the gyro if you touch down in a crabbed attitude and it makes the machine VERY resistant to roll-over.

You don't need a wide trailer. The "Frugal Trailer" link on the Gyrobee website will show how to use a 4' x 8' utility trailer with an cheap set of outriggers for the main gear fabricated from a pair of 2x4s. Don and I have more Gyrobee flight time then anyone else on the planet (although I expect John L. will pass us eventually :=) and, when we ordered the kit for the new machine we specified the stock/plans gear. That should tell you how much we like it.

Ralph

[nsheryka]

I guess what i am going to do is go with a 447, and keep my eye out for a good deal on a 503. If i can find a good used one with not too many hours on it i will use a 503. Too many advantages/disadvantages to think about!!!!!!

[GyroRon]

John Mini, I will be in your neck of the woods sometime this Friday night and staying till late afternoon Saturday. Me and Angelo are going to fly the gyros before I load up the red one to take back here. Already got it sold for him! You going to come up and visit?

[johnmini]

Ron, I'll be there, have to leave early Sat. have a wedding to attend Sat. afternoon. John

[Doug Riley]

Another approach to the narrow trailer/wide gear issue is to make a couple of clamp-on auxiliary wheels to be attached to the main axle tube inboard of the real wheels. My lazy bone dictated this approach instead of widening my existing 6' wide trailer. With these wheels clamped on, the real wheels hang over the side.

A bit hokey, but it works.

A couple waffling comments about engines and gear width:

I found the 447 'Bee to be lively and entirely satisfactory. It does not climb like some of the "showoff" machines do. It is not intended to be such a machine. I would guess that, with my 24.5 ft. Rotordynes and me at 170, it climbs about 600 ft./min. At under 50 mph, that's pretty impressive and certainly all you need. Weight is a serious issue if your 'Bee is to be 103 compliant. My stripped-down version came in at 251. No room for a prerotator. The 503 weighs about 8 lb. more than the 447, so that alone would bust the 103 weight.

Dragon Wings blades weigh less than Rotordynes. You probably can save enough weight with D-Ws to squeeze in a Wunderlich prerotator. You'll be bumping agianst the 103 limit again, though, so watch out for the 503's extra 8 lb.!

OTOH, Ron Awad's right -- the 503 has probably the best reliability record of all the Rotax 2-strokes. The 447 is a bored-out 377, and hence all the components in it are stressed at the higher end of their limit. The 503 is a physically bigger engine (that's why it weighs so much more), so there's a bit more metal to bear the load and carry the heat around.

Landing gear: The wide gear kept me from overturning in the ditch next to the runway while I got re-accustomed to switching between nosewheel steering to pedals (landed and forgot to switch feet). Nevertheless, in a 3-wheeled vehicle, the distance of EACH of the wheels from the center has a effect on stability. Spreading out only 2 of the 3 is less helpful than you might think. The vehicle still has the option of tipping forward-plus-sideways as well as strictly sideways, as the 3-wheeled ATV's proved.

Moreover, gyro tipovers very often are really "fly-overs." A crosswind gets under the rotor, spins it up and the rotor lifts the craft over beyond its control limits -- and splat. Since the process involves the rotor taking most of the load off the gear, it won't matter much how wide the gear is in this common scenario. Several 'Bee pilots (with stock 7-foot gear) have been nailed by this effect at least once.

The wide gear won't make your machine idiotproof. It will make her moderately more idiot-resistant.

[gyropilot]

Don and I have more Gyrobee flight time then anyone else on the planet (although I expect John L. will pass us eventually :=) and...

RalphI wish that were true Ralph. :) Going by memory, I think only have about 110 hours on my Bee so far. There are some other Bee pilots out there who should have in excess of 300 hours flight time.

Anyway, I'm pretty much grounded for the remainder of this flying season as my Rotax 503 engine is in need of expen$ive repairs, and other more pressing money-sucking projects (such as finishing up a new 2-car garage/shop and getting married) have temporarily taken front stage in my life. I expect to get the engine repaired this fall, while also making a couple of new minor airframe modifications. Maybe I'll be able to catch the very tail end of the flying season before the monsoon season hits.

Hopefully next year will *finally* be the year I have time to take some long multi-leg / multi-state cross country flights and really start accumulating the flight hours.

Regards,

John L.

[Ralph]

John,

Well John, you have certainly done a great job of showcasing the Bee out there in the Northwest. I for one will look forward to your exploits when you get back in the air.

By the way, congratulations on getting married. I lucked out almost 36 years ago - best decision I ever made - and that includes flying!

Doug,

Good post. If any of us really knew how to idiot-proof anything, out fortunes would be made!

Ralph

[gilgsn]

I found an interesting page about 447 vs 503 vs Hirth 2702 and 3202:

http://www.heavenboundaviation.com/andyFAQs.htm

Scroll down to #4.

Gil.

[Dirtydog]

You know people looking for a 503 engine should check some of the trikes on brainstorm I saw one in there with all the stuff needed to fly it for $4,000.00 so you are getting a 503 engine, 60" IVO prop with cover, air filters. the muffler has been coated silver also, throttle controls console ect. to go onto your new gyro you are wanting to build....Unless you want new then disregard...... :spy: