Teeter tower Ht.

[rickloon]

How does the height of the teeter towers effect the flying of a gyro? The gyro that I bought recently has very high towers. They are so high that the blades can teeter more than 35 deg. each side of center. This seems much more than is needed and is so much that the blades will hit the ground before full back stick or tilting back on the mains. I have machined a delrin block to reduce this to 12deg each side of center ( total of 24 deg of flap) and from what I have read that should be more than enough for flight and takeoff. However yesterday someone whose opinion I trust told me that it was not a good idea to just install a stop block like that and I needed to either replace the teeter towers or get another rotating part of the rotor head with shorter towers. The photos below show what I am talking about. Any ideas anyone?

[gyromike]

Taller towers were used on the head like yours (Air Command style), usually for rotor blades like Dragon Wings. Even with tip-weights DW's tend to cone up higher than other heavier blades, so they come with a taller teeter block which require taller towers.

Going back with the standard towers would be better than using a stop block.

What type of rotor blades are you going to use?

[Alan_Cheatham]

The height of the towers goes hand in hand with the height of the teeter block which sets undersling, you don't use tall towers and and a short block or you get the results you have.

You can use this spreadsheet from Chuck Beaty to estimate undersling:

http://www.rotaryforum.com/forum/att...3&d=1341767371

.

[Alan_Cheatham]

Also, you don't want to replace the metal upper bearing block plate with a piece of plastic.
.

[rickloon]

I am not replacing any bearing blocks , the delrin piece only acts as a teetering stop and takes no flying loads . I have a set of sport copter blades now ,but it looks like it will be a bit before I am finished with the gyro & I need to get more duel time. I realize the more elegant solution would be to replace the towers and plan to in the future , but at this time was just looking for something that would work till I could.

[Penguin]

rickloon - Alan is right. Get the correct teeter block and you will be much happier with the taller teeter towers than you would with shorter teeter towers. And it's a less expensive fix, too!
I would add that you must not attempt to fly with this combination or with the delrin block.

[Gyro Junky]

The question that presents itself is, are the towers too tall or is the block too short or a combination of both. Obviously something is mismatched. Alan is spot on. Call Vanek and find out what the the proper undersling is for your blades, factored by estimated aircraft weight. I'm guessing the upper hole in the teeter block might be close and then pair the towers to match for your 12 degrees. Other than issues in ground handling as you have discovered, if the block is at the correct undersling, the tower height won't matter, for flight. We proofed this 3 months ago with the same combination. (Dragon Wing towers w/ sport copter hub bar @ 25' blades for both) The Dragon wings do have a relative greater undersling, as Mike pointed out. Your temp solution should work ok, but using shorter towers should be on your to do list if the teeter block checks out ok.

[Alan_Cheatham]

Prying force on the rotor bearing goes up with tower height so it's always desirable to keep towers to a minimum while maintaining the correct undersling for a particular set of blades.

.

[rickloon]

The teeter block on the sport copter blades I am planing to use has only one hole and that should have correct for the under sling as these blades are for a single place of around the weight of my Soma gyro. ( blades 25ft) . I agree , it would be better to replace the towers, but for my purpose (ground testing of pre rotator and practicing ground handling with my non-flyable blades [see post on "not for flight rotor dyne]) I will use the blocks I made. (delrin is a very tough plastic that machines well and I have even used it as a suspension bushing material for off road vehicles in my last machine shop job). True the taller the towers the more leaver you have on the rotor bearing ,however it should be safe as the loads from the rotor feed thru the teeter bolt no mater what the teeter block height so there should be no excessive strain on the rotor head just because the teeter block on the blades is shorter and have less coning angle than dragon wings. If there is something I am over looking please let me know as I am relatively new in gyros.

[Rehan K.Janjua]

You can chop the tower down to size, what ever is needed.

Have to press fit the teeter bearing outer and to be precise
in line bearing the new holes.

It is important to have the right hight to get the proper stick feel
and pressures to control pitch and roll.

Good Luck.

[Ronnie328]

Originally Posted by rickloon

...at this time was just looking for something that would work till I could.

Your life is too important to fly using duct tape and bubble gum fixes. Please follow Penguin's advice! I quoted it below

and put it in bold....
and underlined it....
and am mailing you a plaque with it engraved on it...

Originally Posted by Penguin

I would add that you must not attempt to fly with this combination or with the delrin block.

[Brent_Brown]

Drill holes in the right place in the towers

[hjajr]

I have a aircommand tandem with like 8" towers and a set of holes at the top and at a lower point like 6.
I have 27' Dragon wings. I am wondering why the top holes are so high for these blades and what hole they should be in to fly? Also my other concern is wont these rotor blades fly to slow for one person flying this tandem gyro? Seems like it would flap a lot easier.
I use to have a side by side AC with 25' rotors and when I flew it as a single the rotors turned 275 RPM's and like 350 flying double. Harry

[hjajr]

Also the teeter block has like 4 set of holes in it. it was at the top tower hole and the top teeter block hole. Harry

[Penguin]

The top tower and top block holes would be correct to match the rotor coning. I use these same settings on my 23' DWs. Chuck Beatty has a spresdsheet elsewhere on this forum that helps you to compute the tower heights. Bottom line is - use the highest settings you have on the RFD products.