FB Gyrocopter Experiments

[Hai-Lee]

Sadly I will need to take a few days off of this project as I got an order for 4 planes which I am to hopefully have ready for next weekend.

I also managed to get a copy of the plans, Etc, for the monotwirl which I will be studying to glean further information or technique. More plans will follow here in the next couple of days.

 

[Userofmuchtape&glue]

Ah, yes, are you building planes for friend or do you a business out of it?

 

[Hai-Lee]

Abe, I would hope one day to start a business if I live long enough but in this instance the planes are not of my design and so I cannot charge for them. I had built 5 of the same model a little while ago and last weekend we had a first 'Squadron" meet and had mock dogfights. A great deal of fun was had by all and a number of spectators asked for me to build them a plane as well, (of the same design) so in the following weeks they too could participate in the melee which the dogfights become. See the thread for the Das Little Parkflyer Stick.

One finished and 3 more to go!

 

[Userofmuchtape&glue]

Ah okay. I get it now.

 

[Hai-Lee]

Today whilst I was cutting and gluing the next ordered plane I had a thought about what went wrong with my last attempt at flying the Gyro with the Teeter head. So I checked what I suspected and discovered that I had made a big mistake.

My first rotor head design was made to use blades that rotate in a CCW direction when viewed from the top. When I made my last sets of blades I accidentally made one set of blades that would work on a CW head. As I needed the CCW props for the original design I earmarked the CW set for use on the new teeter head design. I fitted the blades and adjusted the initial blade incidence angle as designed and attempted a take off, BIG MISTAKE!

The rotor head was reluctant to spin up as expected and when I finally took off the gyro rolled onto its right side and crashed. My suspicion fell upon the mechanical resistance of the teeter bar itself. I WAS WRONG!

Today I realised I had designed and built the teeter head assembly to rotate CCW. I quickly fitted the spare set of CCW blades of the new design, readjusted the initial incidence angle to suit the new rotation direction and walked outside into the breeze to see what would happen. The difference was staggering. The rotor head started to rotate almost immediately and when a gust of wind came along the pull from the blades and the "Helicopter" noise was incredible.

Why did it make a difference? well the teeter head has an offset pivot, (Teeter), angle which is designed to reduce incidence angle as the blade rises. What I had done was to fit blades which were designed to rotate the other way. The net result was that as I tried to take off the whole disk lifted the machine with the inertia of the blades keeping the blades level but as they slowed a bit the advancing blade rose and instead of the incidence decreasing it actually increased whilst at the same time the retreating blade fell and its incidence went more negative. All of the lift was suddenly moved to the left side and therefore the whole Gyro rolled away from the lift and crashed.

I may try the teeter head again tomorrow in its current setup to see if it does actually fly and if the new simpler blade design is strong enough to support such a heavy gyro. One unknown problem identified and eliminated.:applause:

Back to the order

 

[Hai-Lee]

Went out today as mentioned last night. Fitted the Teeter Head with the new blades and waited for a clear sky.

When clear I opened the throttle and took off. It did turn into the wind after take off and flew over the trees I did a left turn and ran it effectively downwind. At the end of the downwind run I tried to do another left turn but I suspect the rushed and poor attempt to reattach the tail failed and the tail started to flap. The Gyro rolled towards the advancing lade and fell out of the sky. Damage was the loose tail, (obviously), and a couple of bent rotor blades.

I do have a small video of the takeoff and downwind leg but it is apparently too large at 35MB and I do not do the social media sites. How to post it is a problem!

I may cut a few pics and post them instead in the edit I do next visit.

Here are the pics clipped from the video:

----Ready

----Go

----Lift off

----Over the trees

----Downwind

Anyway if flies and quite simply and really first time:black_eyed:

 

[Userofmuchtape&glue]

Good! It is always a good feeling when you solve a problem. So, will fixing the tail well be enough do you think?

 

[Hai-Lee]

I will need to remove the entire tail to effect the repair and so I may simplify the design seeing as how the tail does not seem to be too close to the rotor blades whilst taking of and flying.

As the redesign will remove some skewers I am thinking of a split vertical stab and rudder with half above the horizontal stab and half below. To reattach the rear of the fuselage I will use glue and some skewers inserted end on into the foam at the scene of the break. With the skewers glued in and the break filled with glue it should be stronger than ever before.

Time will tell. If you want to see the video I might be able to email it but I cannot upload it here.

 

[Hai-Lee]

Repaired the tail and redesigned it as well. Also found a simple "ALL FB" method of further strengthening the blades. Next batch of blades will be of new and stronger design.

Here is a quick photo of the new tail from behind.

 

[Userofmuchtape&glue]

Looks good! Mums business computer is the only one that receives emails, and I found that videos tend to jam it up. thanks for the offer though!

 

[Hai-Lee]

No worries! As for the change to the blades as mentioned in my previous post the plan remains exactly the same with the option of leaving a 10mm piece of paper only added to the leading edge and have the paper folded over the shaped Leading edge and glued into position. This will improve the rigidity of the LE without increasing the TE flexibility.

Another attempt at flying tomorrow, (weather permitting), this series of attempts will be done with a decrease in stub wing incidence to reduce the lift and drag attributed to the stub wing.

May also investigate roll control through a control head pivot and aileron servo, (Next week or so).

 

[Userofmuchtape&glue]

Thanks. Hope it flies better tomorrow!

 

[Hai-Lee]

Did a rough up of the aileron controlled rotorhead using a few old items and some scrap. See Pic!



It seems to work but I will not really know until tomorrow morning.

The planes are on hold for materials to be supplied, (A fortunate delay I believe).

 

[Userofmuchtape&glue]

Ha yes! very fortunate! I await progress....

 

[Hai-Lee]

2 Planes finished and 2 to go! Went flying yesterday first with the adjustable head and it rolled on its side each time I tried to take off. First to the left and the second time to the right. That damaged the blades so I fitted the fixed geometry setup with the teeter head. Fitted my last spare set of blades and took off. Struggled into the air and it wanted to nose up continuously. Headed over the trees and I tried to miss a tree landing. I did miss the trees but it rose nose up and lost all airspeed and started to fall. Half way down one of the blades folded and it crashed almost flat but the landing gear was badly bent and the rotor blades were really damaged.

Today I watched a Panther make its maiden after I had helped him with a build issue or two and upon landing we discussed a few important facts. I learned that I was correct in suspecting my CG settings and that I was following either a bad procedure or I was misreading it.

Next flying day is Wednesday so I will have time to make a few new sets of blades and hopefully the other 2 planes. For the next attempt to fly I will slide the CG much further aft and flatten the coning angle to see if that makes matters better.

 

[Userofmuchtape&glue]

Ahh, thats a pain!

 

[Hai-Lee]

Test flights tomorrow weather permitting. Taking 4 spare sets of blades of 3 different designs. Set teeter bar cone angle to almost perfectly flat and reduced incidence angle of the rotor head. Shifted the rotor further aft to improve CG balance.

Update on previous attempts, found during repair that I had fitted the pylon support assembly on backwards. That meant that the CG was definitely miles too far rearwards and hence the tail down attitude. The blade folded due to wind blowing directly under the rotor disk and overloading the blade.

Anyway tomorrow is another day!

 

[Hai-Lee]

Early morning thunderstorm this morning. No flying this morning at all. Oh Well Saturday is not that far away really. Time to build new Fuselage to the plans, (to verify accuracy), and time to finish the ordered planes.

 

[Userofmuchtape&glue]

Ahh, that would explain some problems!

 

[Hai-Lee]

Far too windy here to fly today but that did not stop me. Fitted the latest design all FB blades and with the revised CG location the thing took off and flew immediately As I turned a huge gust of wind caught it and one of the blades folded and whilst it was still flying I brought it down on landing yet another gust rolled it over and it nosed in and broke the prop and ripped into the skewer holes in the fuselage. Blades destroyed of course.

Fitted the first set of FB and balsa composite blades and a new prop, used extra rubber bands to hold the skewers in place and tried again but a sudden change of wind direction just as I was lifting off rolled the craft immediately onto its side, Picked it up and tried again and after a few attempts I managed to get it into the air believe it or not a huge gust head on actually caused one of the blades to lift massively and the balsa LE snapped but it continued to fly. tried bringing it in to land but it rolled over and the bent blade finally snapped into two pieces,

One other chap with his Panther had only one flight and it ended in major repairs required.

Lessons: The revised CG is far better. The FB/Balsa composite blades are more robust and stronger but still not quite right. Finally scale Cyclonic winds are not recommended for this craft.

Tomorrow is another day.:black_eyed: