Mod to reduce crash damage

[kenny d]

Just thought I'd post this little mod that has reduced my crash damage considerably on my oxy3
so far so good I'm using 3&4s batteries ( never tried it on 6s)
i now use a brass bolt through the main gear to the main shaft
when I crash it shears the brass bolt leaving the main gear undamaged
& a lot less damage to the dfc arms/linkages/main shaft & blades ( feathering shaft still tends to bend)
I've now crashed 7 times with the brass bolts & have noticed a big reduction in damage
I bought them on eBay for a few quid , a bargain when you consider one main gear costs £5
the mod may well work on heli's


UPDATE. , 4 months later & all is working well , the brass bolt has never broke in normal flight , I have crashed over 20 times now
(nothing to be proud of) & I have now saved a small fortune on spares , for me this mod & the oxy3 has realy helped me to push
hard & learn more moves without breaking the bank

[terhoutd]

Hey,
Can you clarify what you mean by "i now use a brass bolt through the main gear to the main shaft"? maybe a picture would be worth a thousand words

[Dean airwolf]

Kenny
Can I buy them in bulk lol.

[kenny d]

Hey,
Can you clarify what you mean by "i now use a brass bolt through the main gear to the main shaft"? maybe a picture would be worth a thousand words

First picture is from the oxy3 manual, the second picture is from a trex 450 but is perhaps a bit clearer
Nearly all heli's I've owned are made like this ,the bolt I'm talking about is the ( scoket collar screw ) in the second picture
it goes through the main gear assembly & the main shaft
I've replaced the high tensile steel Bolt with a brass bolt , when crashing it allows the brass bolt to shear first & helps to prevent damage
to the main gear/main shaft/linkages & blades , the original picture is of the brass bolts I use in the oxy (m2x10mm )

[kenny d]

Kenny
Can I buy them in bulk lol.

Did you notice it's a pack of 50 I bought lol

[terhoutd]

Hey thanks, I see what you mean now.
I have sometimes seen it called the 'jesus bolt'
That's a good idea to introduce sacrificial parts like this. As long as they only 'fail' during a crash and in no case during flight.
I will be ordering a pack of those brass screws!

[Crashalotjoe]

Hmmm, I'm sure it will limit crash damage to some degree but my concern would be that IF it breaks before the plastic main gear is damaged, then it may be inclined to break in flight (which is why they use hardened steel bolts in the first place). Also brass tends to 'work harden' which means it gets more brittle as it is being worked (as in the stresses caused by driving the main shaft) which may well exacerbate the breakage in flight possibility - I'm not sure I'd like to trust my £500 heli with a sacrificial link in the drive train.

[kenny d]

Hmmm, I'm sure it will limit crash damage to some degree but my concern would be that IF it breaks before the plastic main gear is damaged, then it may be inclined to break in flight (which is why they use hardened steel bolts in the first place). Also brass tends to 'work harden' which means it gets more brittle as it is being worked (as in the stresses caused by driving the main shaft) which may well exacerbate the breakage in flight possibility - I'm not sure I'd like to trust my £500 heli with a sacrificial link in the drive train.

I have done over 300 flights now with no problems , it has only been positive with less crash damage , I use one of my oxy's for pushing hard & trying new things so it crashes regularly, it's working for me , as you use the words IF & NOT SURE then don't use them , leave that to us guys with the attitude of WHO DARES WINS

[kenny d]

Hey thanks, I see what you mean now.
I have sometimes seen it called the 'jesus bolt'
That's a good idea to introduce sacrificial parts like this. As long as they only 'fail' during a crash and in no case during flight.
I will be ordering a pack of those brass screws!

i have some spare , as the first batch got lost in the post so they sent more then 3 month later they arrived ! , If you haven't ordered them yet PM me your details & I'll post some to you free of charge , Kd

[terhoutd]

Kenny d, I would like to thank you for this mod idea, since I have used it I havent bent my feathering shafts in the few crashes I have had! This is a golden tip!

[kenny d]

Kenny d, I would like to thank you for this mod idea, since I have used it I havent bent my feathering shafts in the few crashes I have had! This is a golden tip!

thanks for that , I've never done a main gear , the damage to the head is dramatically reduced, feathering shaft always bends so I use these. 6x 450 SE Feathering Shaft For Align Trex T-Rex Helicopter | eBay. A lot cheaper , I also use servo savers ( kst/turnigy/Hitec ) Tarot Plastic Servo Horn Arm 10-Pack For Hitec 65MG KST215 Servo - TL2258 | eBay they are also available for align/savox. , I use the Lynx 250 plastic blades as the are almost impossible to break

[terhoutd]

Thanks I've just bought those 2 too!
If you have a stretch oxy3, do you notice any difference in crash cost compared to the 250mm one?

[kenny d]

Thanks I've just bought those 2 too!
If you have a stretch oxy3, do you notice any difference in crash cost compared to the 250mm one?

Not really, ( only crashed my stretch once ) I am using zeal blades which cost a bit more than plastic ones , other than that it's much the same costs

[Dean airwolf]

Mod
Do what I do don't fly them just look at them on a shelf lol.

[oldnick]

Brilliant idea! So obvious once someone else thought of it...

I'm gambling on my (attempts at) flying improving, I bought only 25 nuts and bolts for the poor 450L, now if I can source some rubber blades I'll be sorted.