Gyrobee Build Update

[Kandace]

Good Evening, I just wanted to send in an update on my progress, I got the axle tubes bent for my Bee, I found a hot rod shop who did it for me. I've now got the tubes on the airframe and the whole thing sitting on the floor, I hope to be thru stage 3 by the end of the week. I'm posting a photo for all to see....Please pay no attention to the shop it is a bit messy.

It is coming along OK now it is more a matter of finding time to fabricate more parts than anything.

Kandace

[gyroblackwell]

kandace,
What parts are you looking for? We (chapter 81 mentone aeroclub) have a small collection of Honey bee parts. I might be able to hook you up with some parts.

E-mail me a list and we will see what we can do. Did you make it down for the convention?


Good luck with your build.

Tim

[Ralph]

Kandace,

The frame is looking great!

Ralph

[CLS447]

Looking good, Kandace! Your shop looks neater than mine! Keep up the good work!

Here's my shop on a good day!

[CLS447]

Not such a good day! That seems like years ago. :eek:

[Chuck Irby]

Kandace, I realize that it is difficult to tell from the picture, but, it appears that the angle braces are attached to the mast and the keel with a bolts through the middle of the square tubing. Is this correct???

Also, I may have missed your post, but how did you fare re the aluminum grading?

[Kandace]

Hi Chuck, Yes it is as it appears. the bolts go thru the center of the square tube, per the plans. Why is this a problem?

The aluminum grading went fine. I didn't post about it though so you you didn't miss it.

My main concern was the fact that the aluminum angles I got had no markings on them. As a matter of fact this holds true for the ones I ordered from Wicks also, not just the ones that I obtained locally. The round tubing and the square tubing all have markings.

[scottessex]

Looks good Kandace, keep us posted.

Chris, I have my own set of bent rotorblades, just like yours!

[CLS447]

Scott, those Rotorhawk blades came prebent with a crashed Bensen I purchased. I just can't throw them out.

Now if you look to the right on the wall, you can see my first set of McCutchen blades with clearance notches cut by my prop on my 447AC. That's what happens when you're in a hurry to show off, with no rotor tach a poor prerotation & poor blade management. I flapped them good! Don't let this happen to you!

I can't throw them out either. It is just trailing edge damage & I think they could be repaired!?!

I wished I could at least flatten out/ straighten the rotorhawks for static display in the local Air museum. Anyone have any thoughts on this? Start another thread if you do. Thanks

[Chuck Irby]

Kandace, some of us (myself included), tend to think there is only one way to do things; our way. The way you did it is simply not the way I would have done it. I don't see the way you've done it as a problem, as long as you don't over tighten the nut so as to indent the 2 x 2 tubing. Please forgive me, for I need to learn to stop posting too quickly, before I think things thoroughly through.

[Dean_Dolph]

Chuck, in this case she is following proven plans that resulted in proven products with a good safety record. If she sticks to the plans then she shouldn't have to worry.

This design originated with Martin Hollmann and when he placed the plans in public domain Ralph Taggart took them and made everything user friendly and promoted it, thus the popularity. Is that correct Ralph?

[Chuck Irby]

Dean, I knew that Candice was following proven plans. However, I have never seen the plans and questioned the location of those two bolts.

[Ralph]

Dean,

There is no doubt that there would not be a Gyrobee if Martin had not designed the Bumblebee, but the Gyrobee documentation is NOT a rehash of his plans. We liked many aspects of what Martin did with his machine and, had kits been available, we probably would have gone that route. Fortunately or unfortunately kits were no longer available, but Martin was selling plans for the Bumblebee.

In our opinion, it was not practical to build an aircraft from those plans, so we elected to build one with the same airframe geometry, but using readily available ultralight components. Development took about two years and, by the time we were done, we felt we had a unique aircraft.

After a few years people started asking for drawings. For many years I required that anyone who wanted to copy my free drawings would have to demonstrate that they had purchased Martin's plans. This helped serve as a filter since I was spending a lot of money sending out the stuff via the mails and often not getting it back! I also started getting a lot of complaints since the price of the Bumblebee drawings was steadily going up with no changes in the package and the builders, comparing the two, could not see any reason why the needed the BB plans. I eliminated the "proof of purchase" requirement when I gave up the mail and went to web-based distribution.

The Gyrobee is certainly a derivative of the Bumblebee and I will never stop giving Martin credit for introducing the first Part 103-legal gyro back in 1984. The Gyrobee documentation is entirely my work, with the exception of "Doc" Watson's work on the new tail group. Despite the fact that the package is free, almost everyone agrees that the package is as complete as any aircraft plans out there.

Ralph

[Dean_Dolph]

Ralph, I sorta knew that! But I thought it was time that the newbees were undated. Thanx!

[Brian Jackson]

Mr. Spadafora,
Thank you for making me have to now pay twice for today's lunch. When I read your post above about those thoughtful "clearance notches"... I had a hard time explaining to my wife why I'd fallen out of my chair laughing so hard! (and consequently what the uncontrolled vomit was all about...eew!)

On a very serious note, thanks to Kandace, I'm glad this subject came up. I, too, was under the impression that all holes in a gyro's rectangular (non-round components) structural members should be drilled such that the nearest perpendicular wall absorbs the bolt compression loads without tube wall deflection. Isn't that why we're supposed to drill as close as possible to the interior walls of the tubing without scoring the walls?

I have every faith in the GyroBee design, but since I'm just learning here myself, does that extra bolt and 2" of angle material constitute a breach in accepted safety practices? I've been told by many long-lived gyro pilots that you should never drill through the middle of any structural member unless it's a round tube. Yet I can't imagine Mr. Taggart going against these practices unless there was a damn good reason.

Thanks for letting me share.
Brian Jackson

[Dean_Dolph]

There have been incidents where there were failures in a mast at bolt holes when subjected to stress, primarily, if not only, during unusual impact. Thus the thought that we shouldn't be drilling holes in the mast and if we do then they should be drilled as you have said.

But I know a Boeing engineer that thinks maybe we are being a little paranoid and that if he tried to use a clamping procedure as opposed to bolts like we do in some cases that he would be fired instantly! I don't know what Ralph's response will be but the empirical results indicate that in this application the bolt isn't a problem.

[Ralph]

Well Brian, everything is there for a reason and the places where the bolts go through the center of the square extrusions do not present problems in terms of stress loading. I an curious however - what EXTRA bolt and 2 inches of angle are you talking about?

There is what would appear to be an "extra" hole near the top of the seat braces, but that is for the bolt and sleeve that will assure that the shoulder harness does not put compression loads on your spine if you have a bad day! The seat brace extensions (and hole) below the keel tube is to engage the front to the tail boom!

Ralph

[DanaLinn]

It is great to see progress.....love the yellow BEE seat that's ready and waiting. Keep the pictures coming and consider posting from time to time on the Gallery at www.StarBeeGyros.com.

It was great to meet you at Mentone,
Laura Linn

[Chuck Irby]

Dean, as you might have guessed, I am from the school of "No holes in the mast (and most other tubing), except at the very ends". I'll continue to build my way, and Boeing can continue to do it their way. :D :D

[StanFoster]

Kandace: Your project will be an interesting one to watch. Keep sending pictures please...and I wish you the best in finishing your Gyrobee and then flying it.

Stan

[Chuck Irby]

Ralph, Brian must have been eluding to extending the two angles to the rear of the mast so that one bolt behind and one in front of the mast could sandwich the mast between them (the two Angles). The keel could have been done this way with no problem, as the angles already extend below the keel anyway.

Due to the drastic angle formed between the mast and the two angle braces, I would have sandwiched the mast between two 1/4" plates, then bolted the angles to the two plates. This would have required no holes in the mast either.

[PW_Plack]

...and after three or four of those modifications, you'd exceed the Part 103 weight limit!

I admire those with the engineering skill to know when these decisions can be made safely, but I also wonder if the 254-pound ultralight limit promotes safety.

[Ralph]

Dean,

I am not sure that was his reference since he said:

"does that extra bolt and 2" of angle material constitute a breach in accepted safety practices?"

All I can tell you was that we had occasion to replace some hardware on the prototype after eight seasons of hard flying (95% of which was off grass) and there was no distortion of any of the holes in the mast or keel, nor any deformation of the surrounding metal. For that reason, the original mast, keel, and braces were not replaced - just some bolts that showed signs of corrosion. Considering that my weight was up around 220 during that period, we had heavy blades sitting on top of a tall mast, and in every takeoff the airframe was being pounded by the sod runway, I have no cause to be concerned about the structural integrity of the airframe.

Also, a few Gyrobees have been dumped during training with the blades up to full speed. The upper part of masts have been bent or twisted (there is no gyro out there where that won't happen), but neither the mast or keel breaks, despite the long lever arm represented by the tall mast. The only thing the Gyrobee has going for it is a long track record as a tough, reliable, simple, inexpensive gyro that will deliver a lot of quality flying. That is enough for some folks and not enough for others. To each his own.....

Paul,

There have been very few gyro fatalities involving true Part 103 machines (there aren't many!) and I cannot think of any that could be related to structural failures. What does kill ultralight pilots is pilot error, inexperience, and pitch stability issues related to PIO and PPO - the same issue you will see with "real" gyros.

Ralph

[Brian Jackson]

Hi Mr. Taggart.
After re-reading my post I realized it wasn't worded very well. I'll be building my Bee exactly according to plans because of your design's amazing safety record and structural solidity. I'm new here and just learning. I was just remembering a conversation with a gentleman I'd met years ago whom was a long-time gyro builder and pilot, named Bob Surgeon (sp). Sorry if the tone sounded rude or anything, as it was truely not meant to be. I was just recalling something from my conversation with Mr. Surgeon that prompted the question.

Looking forward to meeting you on Labor Day!

Respectfully,
Brian Jackson

[Ralph]

Brian,

No problem or offence taken. I seem to end up answering amlot of questions after midnight when I am not my usual amiable self! :=)

I have thought of greatly expanding an FAQ section of the site, but that will take a lot of time. Besides, half the questions are asked before anyone has read through either the website or the documentation. The other half start with "I know that you said XXXXX BUT......"

My biggest problem right now is my server appears to be on its last legs as I cannot keep it up for more than a day or to at a time. Not necessarily a surprise since it has been running 24/7 for over 7 years! I will do a final virus check tomorrow, but it it passes, as I expect it will, I will have to go out on Tuesday, pick up a new machine, transfer all the files, and then try to get it running properly on the network. I'd almost rather go to the dentist!

Ralph

[gyromike]

My biggest problem right now is my server appears to be on its last legs as I cannot keep it up for more than a day or to at a time. Not necessarily a surprise since it has been running 24/7 for over 7 years! I will do a final virus check tomorrow, but it it passes, as I expect it will, I will have to go out on Tuesday, pick up a new machine, transfer all the files, and then try to get it running properly on the network. I'd almost rather go to the dentist!

Ralph

Ralph,

Why not just use a hosting company to serve your files instead of purchasing a new machine? You should be able to get set up for about $75 a year for a basic package (150 MB storage, 1500MB bandwidth). That's including having you own domain name for $15 a year.

Then you don't have to mess around with purchasing a machine, maintenance, etc. Just upload and go. :)

[Ralph]

Mike,

I have given that a thought in previous years (like right before the last major hard-drive upgrade). Trouble is, I run a large number of web-sites, including all my courses, and I need somewhere between 300 and 400 Mb of storage. I have always liked having it right on my desk where I could tinker with everything and getting a new URL for each of the sites is a real pain in terms of updating users. I may spend some time Monday nosing around some of the local providers and talking about site maintainance and other issues.

Ralph

[gyromike]

Gotcha Ralph.

I didn't think of all the other stuff you might have on your server.
Good luck.

[Dean_Dolph]

Paul, the Part 103 254 lb. limit has been a topic of safety discussions since day one. I'm not clear on the history of Part 103 or why 254 lbs. was the magic number.

Everyone keeps hoping the FAA will revisit this and increase it. It seems to me that they were approached about letting gyros add pre-rotators, horizontal stabs and other items considered to be for safety purposes. I don't recall what the response was other than this hasn't been approved. It seems there is always a rumor about the limit being increased so maybe with the Sport Pilot/LSA action over we will see the FAA turn their attention to the ultralight and give us some relief and increase the weight limit.

[Dean_Dolph]

Ralph, what I was replying too was Chucks questioning the drilling a hole in the center of the square tube. I never had a concern and your reponse should put everyone at ease.

[Ralph]

Dean,

The intent of Part 103 was to define a low-energy vehicle. 254 pounds was arbitrary, but any figure would have been. As much as we complain about it today, it was almost 100 pounds greater than the 155-pound limit that existed previously. Those of us who had flown 155-pound ultralights thought it was great!

I periodically hear from guys who feel that some weight liberalization - particularly brakes and prerotator allowances - is just around the corner. That would be great if it happens but I remain skeptical. The FAA feels we have a pretty good deal with Part 103 and now there is Sport Pilot for the aircraft that end up a bit too heavy, fast, or whatever. I suspect that if the pitch is that it is "almost impossible" to build a "safe" Part 103 gyro (meaning one with brakes and prerotator), I suspect the FAA response (with a shrug) is that there just won't be that many ultralight gyros! In fact, I suspect that they were as liberal as they were with Sport Pilot so that:

(1) They don't have to do anything to "fix" Part 103

(2) Within a few years they are really going to start verifying compliance with respect to aircraft operating under Part 103.

Ralph

[Doug Riley]

Holes in the mast: This is more complicated than you might think.

First of all, the mast is ridiculously over-strong for the flight loads it encounters. A really badly scratched inner wall might eventually fatigue, but if reasonable care is taken with drilling, flight loads are not an issue.

The discussions of mast strength really revolve around blade-ground strikes. When a blade hits the ground, it stops but its mate keeps going at 350 mph or better. This produces a tremendous bending load, coupled with a slight twisting load, on the rotor head, mast and frame.

With respect to withstanding blade strikes, the mast is essentially a cantilever beam stood on end. Cantilever beams by their nature are not very strong for their weight, and that holds true for gyro masts. Bending loads that will break a 2x2 (or double 1x2) mast fall between 300 and around 650 lb. Not that much in the best of cases!

In the case of a symmetrical mast section such as we use, the material along a line at right angles to plane of bending through the center of the beam does no work in resisting the bending. Therefore, if the hole is in the center running left-right, the hole isn't significant in case of fore-aft bending (the material removed by drilling the hole wouldn't be helpful anyway). A typical gyro tipover results in a blade strike to the side and a fore-aft bending load -- in which the hole isn't much of an issue.

A blade strike in back causes a sideways bending load. In that case, the material in the outer side walls of the tube bear the load ... and the hole is significant in that case. You can expect the mast to break more easily in sideways bending with the hole than without it. Rear blade strikes are unusual in the 'Bee because (unlike, say an early Air Command), there's plenty of rear blade-ground clearance thanks to the high mast.

An additional question, though, is whether the hole is really at the "fulcrum" at which the bending load is highest. This, in turn, depends on how much mass is located at that point. It's a situation similar to a mailbox post stuck in a glob of cement in the ground -- the post is likely to snap at the top of the cement because the cement makes that point a rigid fulcrum. Put the same post in a hole with just dirt around it and it'll give before it breaks.

In the 'Bee, there's not a lot of mass located at the seat back hole. This is unlike the twin holes at the seat back in a standard Bensen -- those holes were the upper engine mount holes as well as the seat back, so they were attached to significant mass. On a 'Bee, that point is probably not the fulcrum in a sideways bend and therefore not the point of maximum bending load (or moment). It still can break, and it's still somewhat weaker than if the hole wasn't there, but experience and casual (!) analysis suggest that it's adequate as is.

[gyropilot]

The intent of Part 103 was to define a low-energy vehicle. 254 pounds was arbitrary, but any figure would have been. As much as we complain about it today, it was almost 100 pounds greater than the 155-pound limit that existed previously. Those of us who had flown 155-pound ultralights thought it was great!

Here's the logic of where the 254 pound weight limit originated:

PREAMBLE

Part 103-Ultralight Vehicles

Operating Requirements

Adopted: July 30,1982 Effective: October 4,1982

(Published in 47 FR 38770, September 2,1982)


The FAA agrees that the weight limitation for powered ultralight vehicles should be raised from the proposed 155 pounds. The 254-pound limitation was established because it closely corresponds to commenters' recommendations that the weight limitation be raised to at least 115 kilos, and because the vast majority of current vehicles on the market weigh less than 254 pounds. This weight does not include floats or safety devices intended for deployment in an emergency situation, e.g., parachutes and the harnesses and ballistic package necessary for deployment.

[nsheryka]

Personally, and I am by no means an expert, I plan on building my gyrobee directly from the documentation with little to no “bells and whistles” on it to keep it 103 legal. I do fully intend, however to use a pre-rotator and some form of a breaking system (even if it is a simple scrub break, or perhaps a lightweight disk break from a bicycle). Hopefully I will still be under 254, however if I am plus a few pounds I don’t think I will change it, I would much rather be safe than compromise safety for the sake of being completely “legal”.

[GyroRon]

Ok John go get him! :)

[Ralph]

John,

The weight figure, whether in pounds or kilograms, was pulled out of a hat - just don't expect any government agency to admint it! The "hot seller" among ultralights back in 1982 was the Eipper MX - a single-seater with a 35 hp Cayuna engine and semi-3-axis control (differential spoilers for roll). That is the kind of aircraft that people wanted to fly and the FAA can be pardoned if they didn't think that such "vehicles" would get much heavier. Surprise - the MX just slid in under the proposed 254 pound limit!

If they had wanted to avoid being arbitrary, they could have harmonized their definitions with the developing "microlight" consensus in Europe and even the Canadians next door, but there was never any inteerst in taking that route.

Ralph