QB2 Build Progress

Brian Jackson

Platinum Member
Joined
Jul 17, 2004
Messages
3,524
Location
Hamburg, New Jersey USA
Aircraft
GyroBee Variant - Under Construction
Greetings to all. It's taken a few years, a career move and a new marriage to create a stable enough situation for a gyro build project. I started one a few years ago that had to be discontinued for personal reasons, but am beginning anew with a Gyrobee build that I will post progress photos of here.

Today I put a down payment on a zero-time Rotax 503 from 'Rotax Rick' (Ron Davis) and the airframe will be CNC machined with equipment where I work. So it should come together fairly quickly. Blades, Head and Seat are SportCopter, and prop will probably be by Larry Prince (P-Tip). Keeping her stock per plans for the most part but tail feathers are my own design which I'll share on this thread.

Looking forward to participating here again. Have missed a lot of the folks here over the past few years.

Brian Jackson
 

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Great Brian we love build threads!!!
 
Thank you, gentlemen. Feels good. Currently I'm looking at what is involved with the engine mount in order to change from the original 447 design to a 503. I was able to obtain 3D models of both engines to facilitate layout, clearances and airframe hole locations.

Engines are my least knowledgeable area, so anyone whom has made this engine substitution I would much appreciate any guidance here. It appears I can lower the horizontal mounts 5/8", which lowers the thrust line about 3/8" while maintaining 2" of prop clearance from the tailboom. But no cutting or drilling will be done until I have a better understanding of all factors involved. That's where I'm hoping to consult with other builders here that have done this 503 mod.

Regards,
Brian Jackson
 
The 503 is a bit longer than a 447 so the mounting holes are further apart but the same width the 503 is taller and has a bigger fan but that makes no difference in an open uncovered engine.
Norm
 
Just mount rear most engine mount at back of horizontal angle,no need to change any dimensions from original. This leaves plenty of room for fan tower- shroud.
 
Finally paid the balance off for the 503 engine and I have a FedEx tracking number awaiting receipt. Rotax Rick has been great to do business with. Somehow this build project just got real.
 
And guess what arrived today... Now on with the build! This marks a major milestone for me. Hard to believe sometimes it's actually happening.

My-Rotax-503-reduced.jpg
 
SWEET, really happy for you!
Thanks for sharing the excitement with pictures!!!
 
Now THERE's a comfortable-looking pilot's seat.

Seriously, now, the 503 DC is arguably the best engine around for an open gyro carrying a pilot of moderate weight. It has adequate power without the hassles of a rotary valve and water cooling.
 
Thank you guys.

Doug, that was the old prototype seat. The new one is much more refined with a sophisticated paisley pattern that says I'm professional but still have a party streak. TLC wanted to do a story on it.
 
Are you mounting it plugs up or plugs down ?

Does your y pipe have the bungs for the EGTs ?

Carbs tilted up or down ?

Premix ?

Electric start ?

You gotta get one of these....no link ! Bear Perkins Carb unification plate. Check out his catalog....lots of nice goodies....http://www.bearperkins.com/accessories.htm
 
Hi Chris.

You know, half of those questions I simply don't know due to my lack of knowledge about engines. Plugs upward is the standard mounting on a GyroBee. I'm rotating the gearbox 180 degrees for lower thrust line, It has electric start already but I'm not sure how starters work. Do I need a battery or is there a capacitor already in it? Might seem like silly questions but my expertise is in engineering rather than engines... funny they call us "engineers."

I'm not sure what a "bung" is, so can't say if the Y-pipe has them or not. I have the carbs loosely fit onto the ports at the moment and it appears they angle downward slightly, maybe 5 degrees. I will check out the link you added. Thank you for that.

Premix = Yes. I'm told there are nice oil systems to avoid premix, but I'm hesitant to add any weight to the aircraft if there's a lighter alternative. I'm trying diligently to plan the build to make ultralight weight. Ralph's original plans called for a 447 and I decided on the 503 for it's bulletproof reputation. So I'm already heavier right off the bat.

Brian
 
Brian, electric start will put you well outside the Part 103 weight limit. Aside from the starter motor itself, you need a battery (a.k.a. a box of lead), heavy cables and perhaps some semblance of an onboard charging system. The plans 'Bee barely squeaks under the weight limit with a 447; a 503 DC is 7-ish pounds heavier even without the electric start. The 503 block assembly is simply longer, hence containing more metal.

There are a couple spots where you can save a pound or two on the plans 'Bee, but you really have to scrape ounces (and sacrifice creature comforts) to make 103 weight. Welcome to EXTREME no-frills aviation. Start doing those bicep curls on your blade-starting, and recoil-pulling, arm.
 
Thank you, Doug. Makes a lot more sense. The engine came with electric start on it already, but it sounds like I'm going to be replacing that with a recoil pull-starter. True, I could build it heavier and add a few niceties, but part of my passion for this project (besides the sheer joy of flying) is the engineering side. Would really like to meet my goal of UL weight, verified by the scales at a fly-in. That's the goal anyway. Am using an overhead control stick as well, which is significantly lighter than the more common "walking beam" type when you factor in all the rods, yoke, blocks and linkages. Tube and fabric tail. And if memory serves, you posted something about lighter wheels a while back, which I am interested in learning more about.

The only "frill" I'm adding is a folding mast mechanism, which I'll be asking more about in another thread. SportCopter has a folding mast kit for sale but I haven't seen any engineering drawings for that yet.

Brian
 
If you go over 254lbs.........OMG ! You might get caught & you would be in big trouble.......how about it guys ?

Check out Bear Perkins stuff.....Carb unification plate , SS exhaust springs, Exhaust stud kit, red fuel pills, Dual carb single air filter( no chrome cover ).

Bung......threaded ports to screw in EGT sensors. They are at the proper distance from the piston for accurate reads.
 
Azusalite wheels are go-kart wheels made of nylon-reinforced plastic. The prototype Gyrobee used Ken Brock wheels, which were cast-aluminum go-kart wheels. The plastic ones are less elegant, but lighter. You need a 4" for the nosewheel and two 6" for the mains. Buy the better bearings.

Azusalites must be used with tubes. The rim halves are soft enough that the seam between them tends to open up, allowing the tube to drop into the joint, get pinched and develop leaks. There's nothing worse than having your tube pinched.

The solution is to make a shield by cutting a strip out of a plastic bleach bottle, wide enough to straddle the rim seam. Place it on one rim half, install the tube and tire, add the other rim half, bolt it up and inflate.
 
Doug Riley;n1119030 said:
...There's nothing worse than having your tube pinched.

That depends on by whom.

Much obliged Doug on the wheel recommendation. In fact I'm keen on any recommendations for weight savings.

Chris, I will examine the Y pipe tonight. Thanks for the clarification.

Looks like tomorrow I am coming home with a car full of aluminum. A member here recommended a company called MetalSpermarkets and as luck would have it there's a warehouse not far from me. They're letting me come in on a Saturday and pick my own material. No worries about scratches and gouges during shipping. Happened to me before.
 
Quick question for the group: If I am removing the electric start from the new 503, would it have sufficient trade-value for a recoil pull-start system? I would imagine the elec starter might be worth more, but a trade for a like-new recoil unit/system would be OK.
 
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