Hornet folding mast...

[MadProfessor333]

I've already got my airframe set up for the folding mast on my Hornet but after doing a lot of reading I'm thinking about going with a solid 1 piece mast instead.
The folding mast option just seems to be a lot of holes drilled in the mast and everything that I've read says the less holes the better.
But I've also read that the stiffer the mast the more stick shake that could occur so the folding mast may help eliminate some of that.

Can anyone that's familiar with the design offer their opinion on whether to keep the folding mast or go with a solid 1 piece mast ?

Kevin

 

[Aerofoam]

I think the folding mast ends up stiffer than the one piece. I have been told that if you go with the 2- 1"x2" for a 2" square mast,
It is better to orient them front and back instead of side by side because it lets the mast flex fore and aft more and smooths the 2x shake.
I have not done this....

 

[MadProfessor333]

I'm still on the fence as to which will turn up stiffer.....solid mast or folding mast.
I've just been looking at the number of holes being drilled in the folding mast to make it work....that's a bunch of holes.
If I go with a solid mast.....I eliminate a bunch of holes,shed some weight and don't have to make 4 plates & the tube bushings.
I was also thinking about redesigning the #13 plates to put the bolts on the outside of the tube which would eliminate 4 more holes....I've looked at how Denis did his redesign and his bolts are on the outside with 1 bolt through the center of the plate to keep it from moving.

Kevin

 

[Brian Jackson]

Sportcopter and others use an elastomeric bushing on one end that allows the mast to flex fore/aft.

 

[Resasi]

Had the one piece mast on ours, Loved the handling of this machine but did not like the tail which I thought was a weak link.

Denis put a tall tail on his which was a much better way to go. He definitely is the person to ask for advice on any issues on this machine as he continued to refine various weak points in the original build.

Here is my son with ours at Wuachula.




The rotor hoist does stow away.

 

[MadProfessor333]

Had the one piece mast on ours, Loved the handling of this machine but did not like the tail which I thought was a weak link.

Denis put a tall tail on his which was a much better way to go. He definitely is the person to ask for advice on any issues on this machine as he continued to refine various weak points in the original build.

Here is my son with ours at Wuachula.

View attachment 1160537


The rotor hoist does stow away.

Is this Leigh or Stuart Allison that replied ?
I'm still trying to figure out who is who from the screen names.....

Kevin

 

[Sv.grainne]

Is this Leigh or Stuart Allison that replied ?
I'm still trying to figure out who is who from the screen names.....

Kevin

It is Leigh

 

[MadProfessor333]

It is Leigh

I'm still trying to figure out who's who with the screen names....it's difficult and takes time unfortunately.
I watch YouTube vids and then spend months trying to figure out if they are on a Forum or not.

Thanks for the information......

Kevin

 

[MadProfessor333]

Had the one piece mast on ours, Loved the handling of this machine but did not like the tail which I thought was a weak link.

Denis put a tall tail on his which was a much better way to go. He definitely is the person to ask for advice on any issues on this machine as he continued to refine various weak points in the original build.

Here is my son with ours at Wuachula.

View attachment 1160537


The rotor hoist does stow away.

Hi Leigh,
Thanks for the response.
I actually tried to contact you through YouTube a while back.

What specifically didn't you like about the tail.......the handling performance or just the mechanics of the design ?

Yes,Denis is a great designer and I plan to use several of his components on my airframe.....blades,rotor head,hub bar,pre-rotator,etc.
One of his tall tails may possibly end up on my airframe....I'll have to see what the finances will allow,unfortunately.
One advantage that Denis has over most of us is his accessibility to equipment.
He makes parts on a million $$$ machine and I make parts on a $200 drillpress in my shop.
I've tried to outsource a few parts to companies in Louisville & surrounding areas in hopes of saving time on my build but they are outrageous on their prices and I can't afford $1,200 to cut a few gusset plates for me when I'm supplying the CAD files, material and picking the parts up in person.
So,all my parts are hand fabricated at this point.....and it's slow going at times.


On a side note.....
The designer,Don Shoebridge,is a close friend of mine and we spent a few hours on the phone last night discussing a couple of changes that I would like to make to my airframe......he green lighted a few and poo-poo'd a few.

Kevin

 

[Doug Riley]

Kevin: In the 1980s, gyros experienced an "incredible shrinking tail" phenomenon as we moved beyond Bensens to Air Commands, Gyrobees, and the like.

Bensen specified a 2-piece vertical tail of SIX square feet in area. Most successors went with 4 or 5. Some also used all-flying verticals, which are less powerful aerodynamically per square foot than hinged units. Thus they gave up some tail power in the interest of styling and/or weight saving. Not sure it's a good tradeoff.

I flew my Gyrobee with the Watson tail, which is little more than 4 sq. feet. The 'Bee's tail tube is longer than Bensen's, but the vertical tail power still was weak in comparison. Moreover, a half-height vertical tail creates quite a powerful torque yaw at low speeds. On my 'Bee, it took all the left pedal I had to keep the gyro straight at takeoff. I got leg cramps. A tall tail solves this problem, along with the companion problem of torque roll.

A horizontal stabilizer works better if it's mounted high enough to be immersed in the propwash.

The folding mast structure creates a stiff spot in the middle of the mast span -- right where we'd like the mast to be uniformly flexible. Trouble is, a gyro with a mast high enough to accommodate a 60" prop can't fit through many residential garage doors. Without a folding mast, you end up tipping the gyro fairly radically onto 2 wheels to get it through. Just don't lose your grip during this operation!

BTW, I built my first Bensen using a bench drill press that my father's workplace had discarded. I cut my plates with a hand hacksaw and hand-filed them smooth. Yup, it's tedious -- but cheap.

 

[Aerofoam]

BTW, I built my first Bensen using a bench drill press that my father's workplace had discarded. I cut my plates with a hand hacksaw and hand-filed them smooth. Yup, it's tedious -- but cheap.

I have found that a DeWalt 20v circular saw with a "Diablo" carbide tipped combination blade cuts aluminum incredibly well.
The low RPM's of the battery saw are more suited to AL cutting and the blade doesn't get hot.
I have cut hundreds of feet of 1/4" AL with a single blade. 1/8" is a little more difficult, the carbide plywood blade works better and you have to be careful with the feed speed, but the cuts are clean and fast compared to zip disks and band saws, a shear would be nice.......

PS. after marking the cut lines with a sharpie, or awl, rub wax on the line to lubricate the blade as you go....

 

[Brian Jackson]

Hi Leigh,
Thanks for the response.
I actually tried to contact you through YouTube a while back.

What specifically didn't you like about the tail.......the handling performance or just the mechanics of the design ?

Yes,Denis is a great designer and I plan to use several of his components on my airframe.....blades,rotor head,hub bar,pre-rotator,etc.
One of his tall tails may possibly end up on my airframe....I'll have to see what the finances will allow,unfortunately.
One advantage that Denis has over most of us is his accessibility to equipment.
He makes parts on a million $$$ machine and I make parts on a $200 drillpress in my shop.
I've tried to outsource a few parts to companies in Louisville & surrounding areas in hopes of saving time on my build but they are outrageous on their prices and I can't afford $1,200 to cut a few gusset plates for me when I'm supplying the CAD files, material and picking the parts up in person.
So,all my parts are hand fabricated at this point.....and it's slow going at times.


On a side note.....
The designer,Don Shoebridge,is a close friend of mine and we spent a few hours on the phone last night discussing a couple of changes that I would like to make to my airframe......he green lighted a few and poo-poo'd a few.

Kevin

Hi Kevin.

I'm in the same boat... Originally intended to shop out the lathed and machined parts of my build to a local fabricator but the cost was astronomical. For the same price it would have cost to fab two tube end fittings I could purchase a new mini-lathe, which I did. I quickly learned how time consuming machining can be, but if you have more time than money it's a great way to go, and you'll learn many new skills along the way.

I've met Don Shoebridge and had a great visit with him at PRA Mentone quite a few years ago when he was working on a revision to the Hornet drawings. IIRC, there's a lot of machined parts in the design so it might be cheaper and worth your while to look at some inexpensive tools. The mini lathe and benchtop milling machine were around $700 each. If you go that route, https://littlemachineshop.com is a great source for bits and accessories. Avoid anything from Harbor Freight though.

 

[Resasi]

I actually tried to contact you through YouTube a while back.

What specifically didn't you like about the tail.......the handling performance or just the mechanics of the design ?

Hi Kevin, sorry I never really revisited my videos too much and so wasn't the best at responses.

As I have said it was simply my feeling that it wasn't strong enough. I was ahead of Denis at this stage and when I got flying it seemed perfectly adequate, and I was delighted with the handling of the Hornet. Denis decided to go tall tail and have it supported at the top. I thought it did not look as nice so stuck with our Watson type, despite my concerns. I think that Don did a great job with the Hornet and think that you will be very happy flying it.

I subsequently was made aware of the various factors that Doug Riley has pointed out, and, in my next exciting collaboration with Denis and the creation of the GT-VX2/Blue, am more than happy with the tall tail.

Denis and I at that stage were corresponding on our builds and I remember one particular event when I returned from testing the Black Max brakes I had fitted. My previous experiences on a Bensen with very poor braking had convinced me that having good main wheel brakes was an absolute necessity.

It was quite a windy day at Zepyrhills with at least a 45 degree component of cross wind. The gyro did not have the rotor fitted and I did some runs just checking the steering and braking. Delighted with the results I taxied back to the hanger.

It was hot outside and I took a break, checking my emails then found one from Denis expressing concern about the strength of the clips attaching the main axle strut to the keel beam.

I wandered over to look at what he was talking about and found that my quite hard braking had begun twisting the thin metal of the attachment clips. Denis had replaced these with a machined part. On my response to him on what I had found, he immediately sent me a pair of his design, which I then fitted. A great start to finding out what a super nice, talented, gyro fanatic friend that he is today.

I do have to say though that our trailer was built on a Harbour Freight small trailer base, and did function pretty well while we had it.

 

[MadProfessor333]

Not sure if I should start a new thread for each topic or just keep going on this one.

There's been a few issues that I'm addressing during my build :

1. If I can swing the finances I would definitely like to go tall tail from Denis.
I have downloaded the Dominator plans and looked at the original tail design.....man,talk about taking the long way around to get to a destination.
I would almost just go pure wood on the tail and skip all the cardboard,foam,fiberglass,etc....if I built my own tall tail.

2. Here's a topic that I've found quite a bit of debate on through researching conversations.
To caster or hard link the nose wheel ???
I've pretty much decided to go caster.
Now,with that decision being made,I've been researching how to keep the nose wheel from going through the DT's....aka : shimmy.
I understand that there must be friction on the gear to keep shimmy at bay,however,I've not had much luck finding info on the internet showing the exact mechanical design of the Dominator or Carlson aircraft that is used to create the friction/resistance for the gear.
I know the Dominator uses a pinch clamp of some sort and you lossen/tighten the bolt to set the proper resistance.
However,the plans don't show the exact drawing for that mechanism,unless I'm not putting 2 + 2 together correctly.
There's also hundreds of conversations pertaining to the rake/trail of the gear & wheel.
With the gear leg being vertical and the gear plates redesigned to give just a tad more trail...I'm almost inclined to say the thing shouldn't shimmy even without friction resistance.

3. Denis and Leigh have mentioned the possibility of the main gear bracket on the keel tube possibly rotating if hard braking is applied.
Leigh.....were you referring to the bracket rotating around the bolt or was it actually bending ?
Until I can fabricate another bracket or find a better solution,I made a quick fix for the issue yesterday.
As Denis initially did,a simple tab using the existing airframe bolts should work for now.


Kevin

 

[Doug Riley]

Prof:

If you don't mind a bit of a learning curve, formed-and-riveted riveted aluminum sheet and ribs are actually easier than all that composite goo. That type of construction also has a better strength-to-weight ratio than hand-laid composite (Cessna knows what it's doing). EAA has books and (I think) videos on this type of construction.

There's a third possibility for little-gyro nosewheels, besides either pedal linking or free-caster-with-differential-braking. This is a separate steering bar mounted directly on the nosewheel fork, NOT linked to the pedals. Braking can then be nosewheel-only. This was Bensen's original steering and braking setup.

Disadvantages? Two.

First, you must shift your feet from rudder pedals to steering bar once the pedals become ineffective. Fortunately, the rudder remains effective at surprisingly low ground speeds, thanks to prop blast on the tail. Practice without the rotor to learn where you must do the "changeover."

Second, the steering bar will be "push right, go left." This is not unheard-of, as trikes often have the same setup. And, of course, bike handlebars and many children's pedal vehicles are push-right-go-left. If you have a lot of fixed-wing time, though, be cautious about using this system.

I did use this setup on my 'Bee -- but first learned on a Bensen. It's cheap and mechanically foolproof. It will not swerve on landing, and does not rely on comparatively complex brakes, way out on the mains, for steering.

BTW, nosewheel trail provides self-centering, but not necessarily shimmy protection. The wheels on supermarket carts have trail, but frequently shimmy like mad. A Dominator nosewheel has trail, but (in my experience) the shimmy will shake your teeth out unless you crank up that friction collar just short of a total lock! Friction is the key.

Typical trail on a small gyro is around 2 1/2".

 

[Resasi]

Leigh.....were you referring to the bracket rotating around the bolt or was it actually bending ?
Until I can fabricate another bracket or find a better solution,I made a quick fix for the issue yesterday.
As Denis initially did,a simple tab using the existing airframe bolts should work for now.

Actually both. The metal bracket had both twisted and shifted.

As I remember we finally ended up with a machined bracket.

 

[scottessex]

You could modify the Bensen style self centering castering nose wheel.
If you use a drag strut on the main gear it will not rotate.
Pics from my ultralight build.

 

[Mayfield]

castering nose wheel.

Elegant!

 

[Doug Riley]

FWIW, here's my Gyrobee pedal setup. The welded pedals are mounted up-and-forward, as I have long legs and like to lean back a bit. The Bensen-style steering and (scrub) braking are visible. Obviously this arrangement requires a rather large up-down movement of the feet to switch from nosewheel steering and braking to rudder pedals. Again, though, the rudder works (even on the ground) at quite low speeds, so the nosewheel steering gets little use.

My home field is grass, so the scrub brake doesn't get much use, either.


Simplistic? Yup. Inelegant? Probably. Cheap, light, and bulletproof? Totally!

 

[scottessex]

I was at the Macon airport and had to taxi down hill, my poor plywood brake was smoking on my Bensen/KB I had to shut off the engine and pray that I could get stopped before the curve......worked fine in grass.