Gyrobee Download Update

[Ralph]

The prototype Gyrobee has been sitting in a pole barn for the past three years while Don and I messed around with some other projects. Our goal was to get the machine back in the air this summer, but, given the age of most of the airframe components (15 years), we decided it would just be simpler to assemble a new one using a StarBee kit.

To get ready for that adventure, I printed out the 131 page documentation to put together into a builders notebook. When going through the material, I noted that there were three pages (p.6-8, counting the cover as page 1) covering stability and blade selection that were seriously outdated. I also ran on to a number of photos from "Doc" Watson covering the construction of the original "Watson Tail".

To make a long story short, I revised the three pages on stability and blades and added a page of photos to the section on the Watson Tail. The latest version of the documentation (with a revision date of June 2004) is now posted on the download page.

Nothing in the revision impacts actual construction but, if you want to upgrade to the latest version, there is also the option of downloading just the four pages, which you can then print and add to your documentation package.

Ralph

[Curran3]

Ralph,
Thanks for keeping the plans updated and useful. I flew my Gyrobee twice this week and still consider it the most fun for the least money of anything I've ever put in my hanger. Has anyone every modified the structure to allow the frame to lean back? It would allow the unit to be carried in an enclosed trailer and/or stored in a standard garage. I keep running the changes required in my head and keep coming up with problems. It would be nice to see a picture of someone who'd actually done it.
Curran in Jacksonville, FL

[Ralph]

Curran,

Glad you are still having fun! We decided to get the gyro back in the air for the simple reason that no other ultralight we have ever owned has given us more flying with less hassle!

If you unhook the rudder cables and unbolt the tail boom, the airframe will tilt back and go right into a standard garage. If you needed to do that a lot, you could even use pip pins to speed things up.

Ralph

[barnstorm2]

Did you change your no recommendation for Dragon Wings?

I was reading through it reciently and I was wondering why this was. Granted they are hard to hand-spin up but other than that are there any problems?

[Ralph]

The recommendation with respect to Dragon Wings went from negative to positive a number of years ago and I was surprized to run into the old evaluation when reviewing the material. The original stance was based on some of the earliest blades that did not have a reflexed trailing edge. Neither Don or I liked the way they handled on the Gyrobee.

However, once the design was modified to include the reflexed trailing edge, all 'Bee pilots who have tried them gave them high marks - with the exception that they were somewhere between difficult to impossible in the hand-starting department. We intend to use a set on the new machine, which will include a prerotator.

Ralph

[Curran3]

Ralph,
What length blades are you planning to use on your new Bee and what prerotator are you planning on? Given your creativity in the past perhaps some form of ram-jet or turbo?
Curran

[Ralph]

Curran,

We will start with 23 feet. If they need to be longer we can easily (and inexpensively) employ a longer hub bar. Looking at several prerotator options. Lots of latitude given the weight difference between Rotordynes and the Dragon Wings.

Ralph

[Doug Riley]

Ralph: Thanks for bringing the theory section up to date. It's great to have succinct version right in with the construction documents.

From reports I've heard, the 200-plus pound guys will need 24-foot DWs if they fly with a 447 or even a 503 SC. The tradeoff is more bobbing about in rough conditions. 23-footers are probably the ideal size for the standard 525-lb. Bensen-style sport gyro that has around 8 or 9 lb. of gross weight per HP.

And, yes, hand-starting DWs can bring on very abrupt, hard flapping that can easily damage something. You DON'T want to hear that metallic bang out back -- it means you just spent some money!

Whatever tail set a 'Bee builder uses, it should include a horizontal stab, at least partly immersed in the propwash, having an area of around 6 sq. ft. and a negative* incidence of 2.5-3 degrees. This incidence overcomes the effect of the slightly high thrustline and puts the CG ahead of the rotor thrustline. Such a setup creates positive pitch stability and good pitch damping as well.

Dana of Starbee is well on the way to finishing the molds for a suitable fiberglass 'Bee tail that meets these criteria. The Watson works very well, too. Widening the Watson rudder at the top is helpful and more eye-pleasing to some.

* "negative incidence" means the leading edge lower than the trailing edge, as measured with reference to the tail tube.

[Ralph]

Doug,

We really need more data on the use of the DW blades. I flew the 25-foot Rotordynes with my weight up as high as 220-225 with no problem with the 447. I also flew Brock's at 24 feet when just a bit lighter - maybe 215. Those blades were the easiest to hand-start that I ever flew. A few pats and they were on their way up. On the down side they would play out very fast so your round-out had better be right the first time!

Ernie really feels the smaller blades should be used on ultralight machines, but the Bee is really the only machine that works by playing off low disc loading (~1 psf) at modest power levels. As far as the mainstream gyro community is concerned, that is an area of the envelope that most guys haven't explored. I suspect the optimum rotor disc will be either 23 or 24 feet, but it would be nice of some of you DW Bee jocks could provide some observations and evaluations.

I suspect the new StarBee tail will be just what most builders need. The Watson tail isn't bad, but it doesn't lend itself to serial production.

Ralph

[Doug Riley]

There's a minor error in the new section. The Watson horizontal stabilizer has an area of six sq. ft., not four as stated in the text. Its dimensions are 18" chord x 48" span.

I think it's a good idea to keep the HS area around 5-6 sq. ft. This relatively large area lets the HS do its job with only 2-3 degrees of negative incidence and angles of attack that are even less than that (in most flight stances in smooth air).

Note that the HS will not overcome all the nose-over moment during routine flight unless it has around 2.5-3 degrees of negative incidence. If it's at zero incidence (parallel to the tail tube), the craft may nose over to some extent in a low-G, power-on event before the HS "kicks in." This exaggerates the low-G event and is not ideal. Also, the craft may not have positive pitch stability with respect to angle of attack at higher power settings unless there's negative HS incidence.

To compensate for nose-over tendencies created by a slightly high thrustline, the HS must be at least partly immersed in the propwash. The Watson HS location is high enough to do the job. If the HS is completely outside the propwash, the HS's forces will vary only in response to the aircraft's airspeed and angle of attack. The HS forces should, however, also vary in response to changes in power setting. Immersing part of the HS in the propwash accomplishes this result.

[LAWOLF]

Ralph My name is Donald Law and I go by LAWOLF on the forum. I built a Gyrobee frame and then modified the equipment. I saw your web site and loved it so much that I built one. Look under new members and look at Tod Powells coment and pictures of my Gyro. I will fly it this next month or this month and I have all your information. I put a double tail on the LAWOLF and a VW 1600 engine along with a 24 foot extruded aluminum rotor blade and a Suzia gyro head and 4 foot bar along with a 68 inch Carbon fiber pusher prop. I can send you a brochure I made up so you can see. My name is DON also and go by Don Law and I am 70 years old and been a pilot since I was 16 when my father had an aircraft agency. I flew an Aerocoup with no rudder peddles since I was to short to reach them.