FBL Gyro Tuning B.D. Axon Gyro on my T-Rex 700X
- Thread starter Heliman450
- Start date
Smoggie
Well-Known Member
Phil,
One way to tell if the break on your landing gear was due to cold brittle fracture is to put the broken pieces together and see how tightly the fracture faces fit together. If the material was ductile (slightly rubbery) is will have deformed slightly as it broke, the fracture faces won't fit together perfectly, the crack will be slightly open. On the other hand if the break was brittle there wont be any deformation, the fracture faces will lock together tightly leaving no gap.
One way to tell if the break on your landing gear was due to cold brittle fracture is to put the broken pieces together and see how tightly the fracture faces fit together. If the material was ductile (slightly rubbery) is will have deformed slightly as it broke, the fracture faces won't fit together perfectly, the crack will be slightly open. On the other hand if the break was brittle there wont be any deformation, the fracture faces will lock together tightly leaving no gap.
Heliman450
Well-Known Member
I'll check it out asap.
Heliman450
Well-Known Member
Hi all, still a bit off topic but here are photos of the two broken landing gear struts. There is no sign whatever of them having flexed and they fit together perfectly with their counterparts. If I was crazy, I might even have thought glueing them back on would work 
#01
#02 
I think the lesson learned here is be aware that a MAJOR limitation to using the bigger helis is their weight and the possibility that the landing gear might snap at temperatures around zero degrees C (32 degrees F). In future, I'll be extra cautious in cold weather whilst using the standard landing gear and will look into some alternatives, too.
Bye now!
#01
#02 I think the lesson learned here is be aware that a MAJOR limitation to using the bigger helis is their weight and the possibility that the landing gear might snap at temperatures around zero degrees C (32 degrees F). In future, I'll be extra cautious in cold weather whilst using the standard landing gear and will look into some alternatives, too.
Bye now!
Heliman450
Well-Known Member
Hi all, more photos of the damage.........
#01
#02 
Damaged bits, I need to order up one more part (H70G001AXW - Torque Tube Drive Gear Set/22T). As Steve said, the straight gear in #02 has lost some teeth.
#03
#04 
I used a spare pair of landing gear struts so that it can stand on its own 'two feet' so to say until the new parts turn up. Photo #04 shows the 700X alongside my 550 standing at the same height and the tail fin is once again only 7mm from the deck. Not good.
One thing which is a bit of a pain in buying the latest version of a model is that the stores don't have any stocks of the new parts and it's so easy to break something
#01
#02 Damaged bits, I need to order up one more part (H70G001AXW - Torque Tube Drive Gear Set/22T). As Steve said, the straight gear in #02 has lost some teeth.
#03
#04 I used a spare pair of landing gear struts so that it can stand on its own 'two feet' so to say until the new parts turn up. Photo #04 shows the 700X alongside my 550 standing at the same height and the tail fin is once again only 7mm from the deck. Not good.
One thing which is a bit of a pain in buying the latest version of a model is that the stores don't have any stocks of the new parts and it's so easy to break something
Smoggie
Well-Known Member
That's a pain with the blade damage, you would have got away with it without a mark if flying off grass.
The tail drive gear is the same as the previous 700DFC and 700L models so shouldnt be hard to find. The part number is H70G001AXT or H70G001AXW , they are the same thing as far as i can tell, Align-Trex in the UK state both codes for the same item listing: https://www.align-trex.co.uk/m1-torque-tube-front-drive-gear-set-22t-h70g001axw.html.
Check the auto rotation gear carefully for chipped teeth, often when you strip the spur gear on the tail drive it also damages the mating auto gear. Do not get the new red tail drive gears (part # H70G001NX) because they have a different number of teeth and wont fit with the stock auto gear
The UK dealers have good parts availability for the 700X now, they seem to have got a big shipment in just recently.
The tail drive gear is the same as the previous 700DFC and 700L models so shouldnt be hard to find. The part number is H70G001AXT or H70G001AXW , they are the same thing as far as i can tell, Align-Trex in the UK state both codes for the same item listing: https://www.align-trex.co.uk/m1-torque-tube-front-drive-gear-set-22t-h70g001axw.html.
Check the auto rotation gear carefully for chipped teeth, often when you strip the spur gear on the tail drive it also damages the mating auto gear. Do not get the new red tail drive gears (part # H70G001NX) because they have a different number of teeth and wont fit with the stock auto gear
The UK dealers have good parts availability for the 700X now, they seem to have got a big shipment in just recently.
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Heliman450
Well-Known Member
Hi Steve,
I've ordered up the gear set with my local store, just waiting now for the delivery of all the bits.
Last time I flew off grass (the first time, too) the heli almost tipped due to the rotor torque and fortunately, I managed to correct it and get into the air. What would you recommend for such situations in order to avoid that sickening feeling just as it starts to look like going bad? I was running about 10 degrees of right tail rotor pitch, which seems to work on the Spirit Pro but at the moment, I haven't used anything other than zero as the BD instructions say. Unfortunately, at the moment I haven't had it in the air long enough to do any further adjustments.
P.S. Right now, there ain't no grass! We're at minus 6 and about a foot of snow all over. I'm thinking not to risk anything until the thaw comes and my landing gear doesn't just snap off
I've ordered up the gear set with my local store, just waiting now for the delivery of all the bits.
Last time I flew off grass (the first time, too) the heli almost tipped due to the rotor torque and fortunately, I managed to correct it and get into the air. What would you recommend for such situations in order to avoid that sickening feeling just as it starts to look like going bad? I was running about 10 degrees of right tail rotor pitch, which seems to work on the Spirit Pro but at the moment, I haven't used anything other than zero as the BD instructions say. Unfortunately, at the moment I haven't had it in the air long enough to do any further adjustments.
P.S. Right now, there ain't no grass! We're at minus 6 and about a foot of snow all over. I'm thinking not to risk anything until the thaw comes and my landing gear doesn't just snap off
Smoggie
Well-Known Member
Come to think of it, the hard surface probably contributed to the skids breaking in the first place.
You shouldn't really have any problems flying off grass, just make sure that the heli is sitting on a nice level bit of ground and making firm contact at all four corners of the skids. If 'teetering' on uneven ground they tend to spin as the torque builds up.
For the Align tail I always set mine so that (at centre) the arm that moves the pitch slider is exactly parallel to the boom, or as near as the eyeball can detect, see pic below. On the Align tails this gives a couple of degrees of counter torque pitch on the tail blades. I then adjust travel in the FBL until the slider is just short of it's mechanical travel limits at both ends.
But when spooling up always be ready to correct, that goes for flying off any surface, you need to 'fly' the heli before it even leaves the ground.
You shouldn't really have any problems flying off grass, just make sure that the heli is sitting on a nice level bit of ground and making firm contact at all four corners of the skids. If 'teetering' on uneven ground they tend to spin as the torque builds up.
For the Align tail I always set mine so that (at centre) the arm that moves the pitch slider is exactly parallel to the boom, or as near as the eyeball can detect, see pic below. On the Align tails this gives a couple of degrees of counter torque pitch on the tail blades. I then adjust travel in the FBL until the slider is just short of it's mechanical travel limits at both ends.
But when spooling up always be ready to correct, that goes for flying off any surface, you need to 'fly' the heli before it even leaves the ground.
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Heliman450
Well-Known Member
Hi Steve, thanks for bringing a smile to my face when reading your last contribution. The only level ground in Switzerland is man-made, hence, me using the helipad (hard surface 
). We're only allowed on the runway three mornings per year. Of course, if nobody's around then I doubt that there'd be a problem, but after publishing videos of my indiscretions on the Internet, I'm sure someone would mention it to me if not recommending me for expulsion!
). We're only allowed on the runway three mornings per year. Of course, if nobody's around then I doubt that there'd be a problem, but after publishing videos of my indiscretions on the Internet, I'm sure someone would mention it to me if not recommending me for expulsion!
Heliman450
Well-Known Member
There's a no nonsense 'zero tolerance' approach to rules/laws here, which I agree with. It's what creates an ordered society. I prefer to work from within to show our other members that helicopter and multi-rotor pilots aren't all nutters who want to fly their machine straight down the throat of a passenger jet's engine.
The problem is that it's almost impossible for multiple users to fly at the same time when the heli pilots want to fly 3D. Our members are used to around five or six pilots using the available air space together. Their solution up to now is to just ban helicopters from the runway and insist that we stay in our own defined area (albeit with an unfair height limit). We'll see how it goes, for now I accept the rules of the club.
However, there's no reason why I can't prepare a grass take-off area as an addition to the hard, paved area, I am after all, the club's caretaker.
D.O.G.
Goblin 380 Supporter
Can I make a suggestion, I went to our nearest home improvement store and went to the AC isle. There I found a 3'x3'x 1/16th thick sheet metal that I use as my heli pad. It's very light so you can take it with you. It's sturdy enough to keep a smooth and level surface for you heli and it didn't cost $100.00 like most heli pad do. Just a thought.
Heliman450
Well-Known Member
Good suggestion - I've already got a plywood one prepared. It's just one more thing to carry with me along with the heli(s), batteries, video camera, tripod, a few tools etc. etc................ At the moment, all for about three minutes of flight (if I'm lucky). I like the grass idea better, but I'll wait until the spring to cultivate that solution
I've got my to-do list, which includes getting my 550 and other batteries converted to Supra X connectors
I've got my to-do list, which includes getting my 550 and other batteries converted to Supra X connectors
Smoggie
Well-Known Member
Fair enough but there should be room for common sense in this world. A well argued challenge to 'rules' should be welcomed rather than these rules being treated as if they were handed down on tablets of stone. I understand the thinking behind a rule that segregates helis and fixed wing (even if i dont agree with it).. But that only makes any logical sense if there are both helis and fixed wing planes to segregate.. No? If you are on your own whats the possible problem? At best it's a badly written rule.
I guess this rebellious nature probably explains why I cant be bothered with most clubs?
Heliman450
Well-Known Member
Hi Steve, I'm way off topic now but here's the situation. Picture yourself sitting in a club meeting in Aberdeen (maybe not a great choice as comparison in your case) and a foreigner walks into the meeting and starts trying to tell the club how to run their affairs.........
I'm sure the person would be told in no uncertain terms to go back to wherever they came from. That's how it is for me. There's simply no other alternative for flying as no playing fields like your location exist on open land, the owner or some 'nosey Parker' will always challenge what you're doing.
I'm sure the person would be told in no uncertain terms to go back to wherever they came from. That's how it is for me. There's simply no other alternative for flying as no playing fields like your location exist on open land, the owner or some 'nosey Parker' will always challenge what you're doing.
Smoggie
Well-Known Member
I understand. Your situation is different because you need to be in a club to fly, so if you want to fly you have to tow the line, I get it. Fortunately for me the laws here are a little more relaxed, good job too because I'd probably have to find another hobby in your shoes!
So back to the topic... do you have an ETA for your parts?
So back to the topic... do you have an ETA for your parts?
Heliman450
Well-Known Member
No ETA yet, I need to pay them a visit on Tuesday and I'll ask then.
Heliman450
Well-Known Member
Hi all,
Latest update is that I'm still waiting for the new tail gear drive set and a spare set of main rotor blades with no ETA.
In the meantime, I prepared my new 'dummy' blades cutting down the old main and tail blades to use for setup only. They're much more convenient than the full-sized ones and less dangerous, too! I checked out the tail for right-hand pitch and came up with the picture below (sorry that I moved slightly taking it), which just happens to give approximately plus 4 degrees of pitch to counter the main rotor torque. B.D. say that it's not necessary to use any but my tail kicks consistently when spooling up. I'll use it as a starting point having already tested it with zero.
This value gives a slight variation from Steve's earlier picture in thread #28. I measured the degrees using a protractor and got zero using his criteria.
Latest update is that I'm still waiting for the new tail gear drive set and a spare set of main rotor blades with no ETA.
In the meantime, I prepared my new 'dummy' blades cutting down the old main and tail blades to use for setup only. They're much more convenient than the full-sized ones and less dangerous, too! I checked out the tail for right-hand pitch and came up with the picture below (sorry that I moved slightly taking it), which just happens to give approximately plus 4 degrees of pitch to counter the main rotor torque. B.D. say that it's not necessary to use any but my tail kicks consistently when spooling up. I'll use it as a starting point having already tested it with zero.
This value gives a slight variation from Steve's earlier picture in thread #28. I measured the degrees using a protractor and got zero using his criteria.
Heliman450
Well-Known Member
Hi all,
Latest update is that I've got the gear set and whilst waiting, have put together my version of frost-proof (scale?) landing gear so that I can test the next batch of changes without waiting for spring to come. We're expecting a week of substantially negative temperatures but probably not much snow, fingers crossed on that one. Downside on this design is probably that if I come in for a heavy landing the impact will be transferred up into the frame rather than the plastic gear just breaking off. Either way, it costs enough for the main and tail blades anyway, so what's a few more hard-earned into the repair, too. So here are a few photos of the job so far.
#01 Ready for drilling
#02 Fitted 
#03 Ground clearance
#04 Together with little bro. 
Latest update is that I've got the gear set and whilst waiting, have put together my version of frost-proof (scale?) landing gear so that I can test the next batch of changes without waiting for spring to come. We're expecting a week of substantially negative temperatures but probably not much snow, fingers crossed on that one. Downside on this design is probably that if I come in for a heavy landing the impact will be transferred up into the frame rather than the plastic gear just breaking off. Either way, it costs enough for the main and tail blades anyway, so what's a few more hard-earned into the repair, too. So here are a few photos of the job so far.
#01 Ready for drilling
#02 Fitted #03 Ground clearance
#04 Together with little bro.
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