Living with a Trex 250 DFC
Posted: Sat Dec 13, 2014 11:48 pm
Well guys as you know I have been living with the 250 for a good few months now, love this helicopter and tbh it's all I have been flying, but it's biggest Achilles heal out of the box is it's got a big belly, well it's heavy, that and it likes to be a dog and wag it's butt off,
Firstly the wag, as I think this is the killer to the deal,
This is down to bad design on Align's behalf, theyhave to much play in the bearing supporting the tail hubs, these twist in flight and cause binding, as well as the fact they have scaled down the pro double arm tail slider, these two things mean the stock servo, while it is reasonably quick does not have quite what it takes to get the job done, coupled with the 3gx it results in wag and when you dial the gain down to stop the wag you get next to nowt tail authority,
How did you get around this you ask, well a couple of things can be done,
1. Remove the stock tail blade grip bearing and washer, then replace these with two 861xx bearings and no washer
2. Remove the stock tail push rod and guide, and replace with a carbon fibre one I manufactured mine from a piece of 3mm carbon tube with a 1.5mm inside diameter same length as none threaded part of original rod, and epoxied some 450 fly bar head control rods in each end,
3. The last item is to change to a faster servo, now I have got at the moment the MKS DS95i servo on the heli, it is nothing short of amazing, but it's heavy, I mean heavy, I will be trying the DS76t Blade servo next week and I will report how this compares,
All this mind is hard to get the best out of when using the 3gx but I learnt the hard way till I swapped mine out,
After sorting the issue of the tail, I have got to say this little bird flew pretty good, even on my meagre ability, but I wanted to make it better,
Controller and weight, the main problem with the weight is disc loading, it's HIGH
A stock 250 dfc weighs in approx 360grams give or take, depending on cells used, mine was 257g I think,
Now I heard and read about people having brown outs so at the same time as switching the tail servo I swapped the ESC for a Talon 15 as it has a much better bec and as a bonus is about half the weight of the stock Esc, this meaner I only gained 5 grams when I done these mods
My weight now 362g
My next change though was my FBL controller, out came the 3gx and in went a Beastx V3 and holy s**t it transformed the heli, it felt loads more locked in and really stable, but that came at a price, yes you guessed it, weight,
Now she's 370g
Now it's time for slimming world, the fat bird needed a diet,
First I got rid of some excess wiring from esc and sat cables and ties,
Then I swapped the fibreglass canopy for a plastic canopy,
And finally the tail boom was swapped to a carbon fibre item,
The diet is working the bird was down to 348g
This is where in the story I was lucky enough to get hold of a pair of pre production Zeal 210mm blades to try, you can see my write up on these in the heli blades section,
Next diet tip,
My heavy ass beastx, now although this controller was nice and stable it is realy portly, at 20g it's prob the heaviest nearly, I had been hearing good stories and feedback of the Spartan Vortex Vx1e and was close to giving it a go, but managed to get a great deal on a used Vx1n, again I have a short write up in the controllers section, with this swap I managed to lose a nice 11g because of the sat adaptor as well,
Her weight now stands at 337g
But it's not over yet, swapping this week was the place of the servos cyclic to be exact, out came the DS415mg's and in went DS76 servos, not flown this setup yet I will report back when I do, but this was a good slimming and the girls is getting a bit more thin,
Her weight now stands at 320g
With what I have left, the tail servo swap, if the DS76t works out well and stays on the bird she will weigh between 305g and 308g, my batteries are too heavy and I have new ones on the way so potentially the bird could weigh 295-298g,
All this weight reduction should really help this bird with its disc loading and make it so much more fun to fly, we will see, more reports will follow.......
Firstly the wag, as I think this is the killer to the deal,
This is down to bad design on Align's behalf, theyhave to much play in the bearing supporting the tail hubs, these twist in flight and cause binding, as well as the fact they have scaled down the pro double arm tail slider, these two things mean the stock servo, while it is reasonably quick does not have quite what it takes to get the job done, coupled with the 3gx it results in wag and when you dial the gain down to stop the wag you get next to nowt tail authority,
How did you get around this you ask, well a couple of things can be done,
1. Remove the stock tail blade grip bearing and washer, then replace these with two 861xx bearings and no washer
2. Remove the stock tail push rod and guide, and replace with a carbon fibre one I manufactured mine from a piece of 3mm carbon tube with a 1.5mm inside diameter same length as none threaded part of original rod, and epoxied some 450 fly bar head control rods in each end,
3. The last item is to change to a faster servo, now I have got at the moment the MKS DS95i servo on the heli, it is nothing short of amazing, but it's heavy, I mean heavy, I will be trying the DS76t Blade servo next week and I will report how this compares,
All this mind is hard to get the best out of when using the 3gx but I learnt the hard way till I swapped mine out,
After sorting the issue of the tail, I have got to say this little bird flew pretty good, even on my meagre ability, but I wanted to make it better,
Controller and weight, the main problem with the weight is disc loading, it's HIGH
A stock 250 dfc weighs in approx 360grams give or take, depending on cells used, mine was 257g I think,
Now I heard and read about people having brown outs so at the same time as switching the tail servo I swapped the ESC for a Talon 15 as it has a much better bec and as a bonus is about half the weight of the stock Esc, this meaner I only gained 5 grams when I done these mods
My weight now 362g
My next change though was my FBL controller, out came the 3gx and in went a Beastx V3 and holy s**t it transformed the heli, it felt loads more locked in and really stable, but that came at a price, yes you guessed it, weight,
Now she's 370g
Now it's time for slimming world, the fat bird needed a diet,
First I got rid of some excess wiring from esc and sat cables and ties,
Then I swapped the fibreglass canopy for a plastic canopy,
And finally the tail boom was swapped to a carbon fibre item,
The diet is working the bird was down to 348g
This is where in the story I was lucky enough to get hold of a pair of pre production Zeal 210mm blades to try, you can see my write up on these in the heli blades section,
Next diet tip,
My heavy ass beastx, now although this controller was nice and stable it is realy portly, at 20g it's prob the heaviest nearly, I had been hearing good stories and feedback of the Spartan Vortex Vx1e and was close to giving it a go, but managed to get a great deal on a used Vx1n, again I have a short write up in the controllers section, with this swap I managed to lose a nice 11g because of the sat adaptor as well,
Her weight now stands at 337g
But it's not over yet, swapping this week was the place of the servos cyclic to be exact, out came the DS415mg's and in went DS76 servos, not flown this setup yet I will report back when I do, but this was a good slimming and the girls is getting a bit more thin,
Her weight now stands at 320g
With what I have left, the tail servo swap, if the DS76t works out well and stays on the bird she will weigh between 305g and 308g, my batteries are too heavy and I have new ones on the way so potentially the bird could weigh 295-298g,
All this weight reduction should really help this bird with its disc loading and make it so much more fun to fly, we will see, more reports will follow.......
