550e maiden :-(((

[brin]

maidened the 550e today and it was very smoothe and stable .did a few flips and started to do some tic toc's which felt good then put some more pitch in and had a boom strike :-(( .Not quite sure what the cause was but either a link came off or to low a head speed.I was flying at 70% with 550 blades.?.I should have checked the idel up 1 and 2 settings.
idle up 2 was at 100% and 1 was 69% .I just copied the model from one dx8 to the other.but onward and upward as they say.:-)

[ROCKET RONNIE]

550e maiden :-(((

Well done mate, I fly my 550 dfc with 550 blades and smack it about with no boom strikes ??? Kony esc 100 lv and TC are 70% and 90%

Have a good look at your links and head movement ?? They are a good heli

[coolice]

Hey.

Sorry to hear this has happened.

How tight where your blades to in grips? Loose blades combined with a low head speed, will provide the ingredients for a boom strike unfortunately. 550 mains will of course bring the blade tips closer to the boom as the blades lead & lag.

With a link coming off you normally hear some things happened first, then you hear a flutter sound as the blade flaps in flight.
.

[trillian]

Sounds like maybe it needs harder dampers or more pre-load on them?

[ghost2212]

Is it DFC?

[brin]

yeah dfc.blades were tight and dampers should be ok./

Is it DFC?

[ghost2212]

Re: 550e maiden :-(((

yeah dfc.blades were tight and dampers should be ok./

Is it the 550 or 600 boom?

[milly0812]

550e maiden :-(((

Is it the 550 or 600 boom?

Was gonna ask this too as I ran 550 on standard boom with 85 tails and had a little main/tail interaction lol

[brin]

I was sure the the blade folded befor the boom strike but others thought it was a boom strike.The turnbuckle was sheared off by the head button and the alieron link rod is missing.

Well done mate, I fly my 550 dfc with 550 blades and smack it about with no boom strikes ??? Kony esc 100 lv and TC are 70% and 90%

Have a good look at your links and head movement ?? They are a good heli

[dillwhacker]

550 mains will of course bring the blade tips closer to the boom as the blades lead & lag.

Sorry for being as thick as a whale omelete, but what does lead / lag to do with it?
550 blades will obviously come closer to the boom at high negative pitch, cos they are longer, and at low headspeed they are more bendy.
How does lead / lag affect this?
Have I missed something here?
Taa
Trev

[brin]

600 boom

[SamS]

Hey Brin, sorry to hear this

Don't suppose the headspeed was too low (and blades maybe slightly too loose) to 3D it ?

[brin]

just been told that the head speed was govened .so not sure what the head speed was as all i did was flicked into idle up 1 and assumed that was the set speed.
Not being used to flybarless and not used a esc govenor before .A big learning curve i think.

[coolice]

Sorry for being as thick as a whale omelete, but what does lead / lag to do with it?
550 blades will obviously come closer to the boom at high negative pitch, cos they are longer, and at low headspeed they are more bendy.
How does lead / lag affect this?
Have I missed something here?
Taa
Trev

Hi Trev.

With a boom strike such as this one we're trying to analyse, lead and lag is another important consideration and something to eliminate and make people aware of especially on DFC models.
Early on there had been a few 700E DFC boom strikes and in one video which is slowed down at the crucial point, you can clearly see the blades lag. This machine is designed to run 690/700 length blades, so is not running longer blades. The 550 in this topic is no different to a 600EFL running 600 mains, but a chain of things has lead to a boom strike on this occasion.

I'm sure you know what is meant by lead lag?
What can happen is as the rotor disk is loaded and unloaded with collective pitch changes, it speeds up or slows down, loose blades can then lead/lag as the rotor head speed changes. The blade(s) then can get even closer to the boom.
As an example a friend recently changed blades on his 700E DFC, then proceeded to fly the same hard flight, using the same head speed as previous and had a boom strike. The only difference were looser blades in the grips.

Obviously we will never know the true cause and boom strikes come about from many factors, one of which can be longer blades, loose dampers etc. However, if this is a 550E V3 DFC then it will have the hard Align POM dampers, so there is no rubber damping at all.

I was sure the blade folded before the boom strike but others thought it was a boom strike. The turnbuckle was sheared off by the head button and the aileron link rod is missing.

Hey.

I'm wondering if the blade folding you saw was the blade shifting within the blade grip?
During a tic-toc is a classic time for the blades to move within the blade grips, as you are quickly on & off the pitch and so the governor is trying to keep up with rotor rpm changes by varying the throttle.

Unfortunately we'll never know, but can only help alleviate the problem in the future once you've got the model rebuilt.

just been told that the head speed was govened .so not sure what the head speed was as all i did was flicked into idle up 1 and assumed that was the set speed.
Not being used to flybarless and not used a esc govenor before .A big learning curve i think.

It might be good to check the ESC is setup correctly, I am assuming you have a CC Talon?
I recently saw a model, setup by someone else which had the wrong gear ratio input into the ESC's settings. Of course this will then effect the rotor RPM, as the ESC's governor will be working with the wrong information.
Will be worth checking the set rpm's and the information the governor needs to run effectively, just in case.
.

[Varelco]

The best way to see it is Bend a blade in its grip then put some pitch on the blade grip, you see how much the blade tip moves higher/lower. Its an Exaggerated way of showing it but its the same principle.