kriegsmacht

My Feedback: (12)

I've been following this forum for a while now, because I'd really like to fly an autogyro. The impression I get is that it's not a strict science yet and there seems to be some uncertainty as to the best design. I'll just tell you what I have in mind and I would appreciate the gyro experts here offered some advice or suggestions.

I'd like to have the simplest design (mechanically) as possible, even if it lessens flight performance. I like a challenge to fly much more than adjusting linkages and hinges all over the place. From what I gather, that would be the 3 channel. Throttle, rudder and elevator. I planned on using the fuselage from one of my lighter planes, probably about a 25 to 40 size. I'd build the pylon and 3 rotor hub, and for now, probably buy aerobalsa blades. I'd remove the stock tail control surfaces and double their area.

Does this seem reasonable so far? I think so.. but heres the real issue:

It seems basic to build a pylon and stick it on a fuselage, assuming you use the proper angles and balance everything. The thing that I am still unclear on, even after reading post after post is the construction of the actual hub.

Ok we have tilting hubs and fixed right? Furthermore, we have flapping and lead-lag hinges and hinges with delta angle built in, (articulated?) but also there are rigid hubs which only lead and lag, correct? So the question is with my planned build of a 3 channel rudder/elev only, would a rigid hub work? I saw a photo of a cub converted to a gyro which used 5 blades. The hub looked very basic, just a disk with holes for attaching the blades. I think a steel ring which would attach on top of the blades might increase strength and stiffness. Just a free floating ring held on by the blade attachment bolts.

Anyway, I'd appreciate any input on what the simplest hub necessary would be for my application.

tintrax

Side tilt for the rotors is not hard to make, and gives positive control. Elevators are fine so fore & aft tilt is not necessary. Forget about lead/lag. Try a rigid (non tilting) hub if you want to but it is not something I want to do! The hubs I make are simple but do the job OK.
My hubs are shown on my website. I make my own blades too, no great problem.

NMOSSON

Do not increase stifness of the blade holder disc. Ideally, it should not have any stiffness (i.e. no transmission of blade bending moment to the head through a hinge) to avoid dissymetry of lift. Can be done using polypropylene sheet sandwiched between wood except at hinge location (Jim Baxter design) or more simply by using a glass fiber plate (not more than 2mm thickness) if you add enough tip weight to the blades.

kriegsmacht

My Feedback: (12)

Thanks everyone. I found the post with photo I mentioned before. Click and scroll down to the 5th post if you want:

http://www.rcuniverse.com/forum/m_48...tm.htm#4839188

NMOSSON, I assume this uses the second type you mentioned.. the flexible fiberglass plate. I guess I could PM the owner and ask. At first glance, I just assumed it was metallic.

About the upper ring, I just thought it would be stronger mechanically, but yes it would make it almost completely stiff. It seems unnatural to mount a rotorblade by just one side. But if stiffness is a bad thing, I'll scrap that idea.

How long till the holes in the plate wallow out into an elongated shape?

EDIT: Would something like this be suitable?:

http://cgi.ebay.com/ebaymotors/4409-...spagenameZWD1V

kriegsmacht

My Feedback: (12)

Additionally: http://www.cstsales.com/fiberglass_composites-ss2.html

Or http://www.jandq.com.tw/show_prod18....e=1&sys_code=6

Does anyone know of a better source? I have heard of the first place listed before.

Edit: CF Plate also! (scroll 3/4 of page)

http://www.cstsales.com/carbon_composites-ss2.html

teufelhund

My Feedback: (2)

Try this one guys, Custom made for our specific use. http://www.mjpcarbon.com/r_c_plane_mounts Cya, Ben

kriegsmacht

My Feedback: (12)

AWESOME!! No need to bother with anything when you can get it ready made for 10 bucks!

Thanks a lot for the help. I'm sure I will have more questions later for all the experts here. I will post photos of the project as it continues and will probably need some info on what size rotor blades would be best. It's a rather large 40 sized fuselage.

imsofaman

My Feedback: (2)

Hey guys...sorry I hit the forum late. Glad to see that Kriegsmacht has been steered nt the right direction. For a 40 size fuselage....the plate from MJP carbon should do the trick. MJP Carbon also make the same plate but wil .400 dia. holes to accomadate the mounting bolts for the rotors. this acts as a base plate. This will allow the rotor to flex up as it passes over the front of the aircraft, but it keeps the rotors from slapping down...... like during a rough landing. Go to the MJP Carbon site and write to Mark and tell him you wan the rotor plate of G-10 fiber glass and the bottom support plate of 1 mm Carbon fiber. To this day....I dont know why he is not showing the bottom CF plate on the web site. I hope to fix this problem soon.

Dave

kriegsmacht

My Feedback: (12)

imsofaman,

I plan to order the fiberglass plate with the blade mounting holes as you suggested, but I am a bit confused about the "bottom support plate"

Isn't the fiberglass plate mounted to a hub, the blades are mounted to the plate and thats the whole system? Or am I off base again?

imsofaman

My Feedback: (2)

Hold on....getting the photos....

imsofaman

My Feedback: (2)

These are from my DAG-1 build guide CD. The black plate is the Carbon fiber. This is the Carbon fiber bottom plate that keeps the rotors from flopping down too far. The rotor plate is made of G-10 fiber glass and is flexible.

Dave

imsofaman

My Feedback: (2)

SWEET....right????

Dave

imsofaman

My Feedback: (2)

kriegsmacht ,
Does it make sense now...or did I loose you?

kriegsmacht

My Feedback: (12)

Ahh yes I see clearly. In flight they won't be touching the base plate anyway, so they are free to drop down a hair or flex up a hair depending on thier individual needs, however at no time should they droop or slap any lower than when in contact with the base plate. Like you said, in a bumpy landing. Should help to prevent the blades from ever striking the tail as well?

It's beginning to look like a piece of cake now. I have the fuselage with engine and radio, and a source for a rotor plate and blades. All I need is to attach a pylon and come up with some kind of actual bearing device to mount the plate to. I guess it would be wise to consider that part before building on the pylon. I have noticed some are using R/C car parts.

I just now drew this up. I have unlimited access to a metal lathe, so whipping something like this up out of aluminum shouldn't be hard.

NMOSSON

See below an other exemple of rotor head on 40 size gyro (Japanese KIRARA).

imsofaman

My Feedback: (2)

kriegsmacht......one more thing, dont forget to have a good amount of downthrust on your engine. That is very important and that was something I did not pay too much attention to in the begining. I have learned in time....it plays a large roll in how it flies. It really makes the gyro fly lighter and bleads off the speed a little. After all....you are not looking for speed. You are looking for stability.

Dave

kriegsmacht

My Feedback: (12)

imsofaman: Ok, I'll remember that. I planned on using the specs provided here to go by:

http://www.autogyro.com/technic/specs.htm

This recommends 5 degrees down (3 to 8), I'll be sure to build this in. I'll surely have to modify the plane fuselage as I'm sure theres not that much already.

Nmosson: Thats a beauty. 2 blades no less! Also no base plate. Looks like that ones over my head till I get some flying experience. Thats a production hub right? You didn't build that did you? If so, what are those parts?

imsofaman

My Feedback: (2)

Good luck with the build.....post some photo. We are here to help!

Dave

kriegsmacht

My Feedback: (12)

Will do. Not just going to talk about it, I'm on it. It may be later this winter since I plan to try to build some of the parts, but I WILL have a working gyro even if I have to buy a kit.

imsofaman

My Feedback: (2)

autogyros of arizona may have what you are looking for. They have a couple new models that may be exactly what you are looking for.


Dave