Jet Gyro - Page 5 - RC Groups
Thread Tools
Feb 22, 2017, 11:17 AM
Registered User
orvie6's Avatar
Thanks Steve for your input. I read your Ac20 thread. I am doing a redesin of mine and think I will go for an open cockpit. My gyro is about 4 inches wide due to the edf unit, but think I can come up with a compromising fuselage that will look right. Thanks again for your input.

Wayne
Sign up now
to remove ads between posts
Feb 23, 2017, 10:01 AM
I'm not as bad as they say.
You have an overly stiff rotor hub. You also have some coning induced roll.
The overly stiff hub is giving you some nose up due to forward motion and making the controls be out of phase.
The coning induced roll is giving you a strong roll to the right.
It's clear in the still picture that the rotor has already decided to pitch up and right before you lift off. Nothing in the fuselage is going to do much about this.

You need to go to a flexier rotor hub, possibly add some tip weight, and put in some aileron trim to compensate for the roll you are going to get to the advancing side when the rotor loads up and cones.

Good luck.
Latest blog entry: AIrcraft I've built.
Feb 23, 2017, 10:17 PM
Registered User
orvie6's Avatar
Mickey, thanks very much for your comments and advice. I scratch built my head from 1/8th inch ply and the hinge from a storage container from Wal-Mart. Also the blades were made from 3/8 x 3 x36 balsa cut down to 30 inches long. The chord is the full 3 inches. I used 3/32 music wire in leading edge. Are my blades too wide? Mark from Flying Balsa said he would be making blades again in the near future. I am building a new version soon and will make some changes that should reduce some weight and make it easier to make changes to. All comments are welcomed.

Wayne
Feb 24, 2017, 08:07 AM
I'm not as bad as they say.
Quote:
Originally Posted by orvie6
Mickey, thanks very much for your comments and advice. I scratch built my head from 1/8th inch ply and the hinge from a storage container from Wal-Mart. Also the blades were made from 3/8 x 3 x36 balsa cut down to 30 inches long. The chord is the full 3 inches. I used 3/32 music wire in leading edge. Are my blades too wide? Mark from Flying Balsa said he would be making blades again in the near future. I am building a new version soon and will make some changes that should reduce some weight and make it easier to make changes to. All comments are welcomed.

Wayne
I think the gap is too small, at least on the top side. The first thing I would do is bevel that gap so that the blades can flap freely in the up direction, at least 30 or more. The head cannot be rigid when the blade flaps up otherwise all kind of bad things happen.
I'd probably bevel the bottom also.
This is the advantage of the G10 heads, they are stiff enough to keep the blades from drooping when you are not moving, but flexy enough when flying.
We went through the phase making heads like you have 10 or 15 years ago, they are tricky to get to work right. A simple triangle made out of 0.040 or 0.062 G10 will probably be easier to get trimmed out.
Latest blog entry: AIrcraft I've built.
Feb 24, 2017, 02:39 PM
It's all in the Blades!
SafeLandings's Avatar
Maybe worth trying the head and blades on a known fly model? that would give you a definitive answer.

Here is a video, I am sure Rich won't mind me posting because it shows exactly the effect of lack of vertical area, the model has quite a decent sized fuselage as your has but his has a lot more vertical area. He cured this by adding tip fins out in the clean air.

The unknown is your air flow from the ducted fan, all the joys of trying something new. Would it be worth tethering it from the rotor spindle, applying power and seeing if the vertical fin holds it in position through the power range?


First Flight, first crash, new design model autogyro (0 min 26 sec)



Rich
Last edited by SafeLandings; Feb 25, 2017 at 04:13 AM.
Feb 24, 2017, 06:41 PM
Registered User
orvie6's Avatar
I want to thank all who have given advice and comments to my situation. Due to the low density of my foam (1/2inch blue Dow insulation) and my many upsets, I decided to do a new build of the gyro. I will be using the Model Plane Foam. It is similar to depron. Will use the same basic design. I will not have the foam until a couple of weeks. So no testing for awhile. I will post pictures and comments as I do the build.
Rich, I will try the "powered hang test" and post the results. One question I have. I am using a homemade two axis control head but plan on "fixing" the pitch control with an adjustable rod. Using elevator for pitch. Is this recommended for a gyro this size?

Wayne
Feb 27, 2017, 02:43 PM
Registered User
orvie6's Avatar
I have been reading Tom Wrights thread on his Crane Fly. A lot of good discussion on blades,mast height,etc. I think I will try out my changes using my blue foam, then make my "good" model from the better foam. Will probably start on it next week. Will see if I can reduce the airframe weight using the blue foam. Other weight savings will be gained by different wheels, one less servo, (decided to use rotor pitch control). May use a mix of the blue foam and dollar tree foam in the non structural areas. Will post progress as I go.
Mickey, I will be getting mechanics for a 450 size heli from a good friend of mine. Would this size gyro (60 inch 3 blade rotor now) work with a 72 inch 2 blade rotor with the swash plate set in fixed pitch? (use cyclic only, no collective.)
Wayne
Last edited by orvie6; Feb 27, 2017 at 03:19 PM.
Feb 28, 2017, 05:42 AM
I'm not as bad as they say.
Quote:
Originally Posted by orvie6
Mickey, I will be getting mechanics for a 450 size heli from a good friend of mine. Would this size gyro (60 inch 3 blade rotor now) work with a 72 inch 2 blade rotor with the swash plate set in fixed pitch? (use cyclic only, no collective.)
Wayne
Depends, without a gyro it might be touchy. I've done it successfully with flybar heads, with slightly longer flybars.
You might need one of the electronic flybars to keep if from being too sensitive to the controls.
Latest blog entry: AIrcraft I've built.
Feb 28, 2017, 08:04 AM
Registered User
Quote:
Originally Posted by orvie6
With the rainy weather making any testing dificult, I have been doing some further experimenting. I was able to do some taxi test in the street where I live. I was able to get the rotor up to flying speed and was able to get the gyro to lift off but no room to really fly. In looking the gyro over, I Decided to make some changes. For one thing, I had two servos in the aft end of the tail boom! One for the elevator and one for rudder/steering. I built a new gyro over the last 3 days. I like this one better. I also added some length to the nose to get away from adding dead weight. I was able to use the elevator and the landing gear. Every thing else is new. Hope to do some testing this weekend.

Wayne
looks cool ,good luck Wayne
Feb 28, 2017, 08:07 AM
Registered User
Quote:
Originally Posted by orvie6
Ok. I have gone on a little side trip and have built a smaller jet. It has two 64mm fans. The rotor system on it is the same as the Whippet. Hope to do some testing tomorrow.
Again, all comments are welcome.
Wayne
looks good Wayne ...
Mar 03, 2017, 08:46 PM
Registered User
orvie6's Avatar
Was able to get some more blue foam today, so starting to rebuild. Making a smaller model to try some of the things that I received from your input. Hope to have some photos later this weekend.

Wayne
Mar 04, 2017, 05:13 PM
Registered User
orvie6's Avatar
Had a slight problem today. Was installing a pair of 64 mm fans and checking them out when one of them slowed down and smoke came from the esc! So, took the 64s out and putting in a single 80 mm fan. Will try and get some pictures later today.
Wayne
Mar 04, 2017, 08:20 PM
Registered User
orvie6's Avatar
Got the fan mounted and servos installed. The tail boom will be triangler in cross section and transition to the rectangler cross section under the fan. The control head is a simple roll only head. The mast tilt is 8 degrees. More tomorrow.
Wayne
Mar 04, 2017, 08:28 PM
PSALM 14:1
Sammy70's Avatar
You're a building MACHINE Wayne!
Mar 05, 2017, 08:58 PM
Registered User
orvie6's Avatar
Got some more done today. Made the landing gear. When on the gear, rotor is tilted back 21 degrees. Also finished the tail boom. Maybe hard to tell by the photos, but major cross section is a triangle. Also started on the tail feathers. Stab is just taped in place. There will be tip fins on the stab with a low profile fin and rudder. Mast is also mounted. May start on the cabin tomorrow.

Wayne


Thread Tools