• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

500 size Apache Gunship Build

F106DeltaDart

Well-known member
#81
Just found out that there is a TFR in the area tomorrow. Figures, the only nice weather scheduled for this week and we get a no fly zone.. May have to try for a maiden tonight if there is a break in the winds.
 

F106DeltaDart

Well-known member
#82
Well, I did technically get it in the air yesterday night, by maybe 3-4 inches. It would appear my predicted head speed was on the low side for maintaining tail rotor authority, even with the 4 blade tail rotor. When I lifted off, it would hold fine through the pull to pitch, but just as the chopper leaves the ground I would run out tail rotor and have to set it back down. I switched to a 14 tooth pinion, which helped a noticeable amount, but I was still bottoming out tail rotor to hold a hover. I will try a higher tooth count pinion to see if I can get things sorted out. Just have to wait on another order now.
 

F106DeltaDart

Well-known member
#85
Just got in some new main and tail blades to test as well. The increased headspeed helped lift off quicker, but tail rotor authority was still lacking. I did finally get it out to the field though! More painting and balancing scheduled for tonight, and maybe another test flight tomorrow.
image_17490.jpg
 

PsyBorg

Wake up! Time to fly!
#86
I found a new project for you. This is one unique helicopter I have never seen or heard of until like 10 minutes ago.

 

Fluburtur

Cardboard Boy
#87
Aaaah a intermeshing heli! I want to build one but I have yet to get a rc heli (but that's on my plans).
Fun fact about Karman helis, they don't use swashplates but little flaps on the blades to change pitch.
 

F106DeltaDart

Well-known member
#88
I found a new project for you. This is one unique helicopter I have never seen or heard of until like 10 minutes ago.
That would be a fun one! I would love to do the older Kaman HH-43 Huskie someday. Was one of the first rescue helicopters to enter service in Vietnam. Would certainly be an intense build, especially figuring out the control system and making sure the blades can stay locked out of phase.

I have another update on the Apache as well. I changed out my main rotor blades to some wider chord Rotor Tech 430mm blades, and they handle the weight much better than the smaller blades. They look less scale, which is unfortunate, but I can hover now!! I was able to several 3 ft hovers without the tail slipping out yesterday afternoon! However, I was still at max left tail rotor to hold that position. Unfortunately, after several test hovers, the left gear decided to collapse and ruin my brand new blades. Now both main landing gear have been reinforced and there is a new set of mains on the way. Also have a couple of different options inbound for tail rotor blades. It's been a long and painful road, but it looks like success might finally be in sight!
 

PsyBorg

Wake up! Time to fly!
#89
I was going to suggest either a wider cord on the tail blades or going a four blade tail vs two. What is your gear ratio of the main to tail? is it a torque tube set up or belt driven?
 

F106DeltaDart

Well-known member
#90
I was going to suggest either a wider cord on the tail blades or going a four blade tail vs two. What is your gear ratio of the main to tail? is it a torque tube set up or belt driven?
Setup is torque tube, with a 4 blade tail rotor, and a tail to main ratio of 3.6:1. In comparison, a stock Trex 500ESP has a ratio of about 4.6:1. This is because the Apache is running a special smaller diameter gear set to allow the mechanics to fit in the thin fuselage. Autorotation gear is 112T with a 31T tail drive gear. The other thing working against me is the large wake blockage from the vertical fin masks a lot of my tail rotor thrust, and I am limited on tail rotor blade length by the location of the H-stab. I can still go up to about 80mm length, but that's the max. Really hoping that the blades end up solving the issue though, otherwise this could get very difficult.

IMG_1756.JPG
 

PsyBorg

Wake up! Time to fly!
#92
How much a factor is the tail rotor not being true X effecting the amount of air it can move? Seems that there is more time where two blades are pushing the vertical surface possibly more. I know it wont be perfect scale but you may be able to shave the top of the vertical stab lower at that crease line to open the top more if you find you cant move enough air with the planned changes as well.
 

F106DeltaDart

Well-known member
#93
Can't you mount those at an angle when the stick is neutral or would that create other problems?
Actually, I did dial in a few degrees of left bias on the tail. It helped a bit, but not much.

Psyborg, your comment about the tail gear ratio may have solved my issue! Originally, the Apache was meant for belt drive, and I converted it the torque tube using some spare drop down gears from a Blackhawk fuselage. The drive gear looked like the exact same machined brass gear as the belt drive gear that came with the Apache, so I never gave it a second thought. So, I dug around through my parts drawer and found the original gear. Sure enough, it was 26T vs the 31T gear that I was using from the Blackhawk. Swapped on the new gear, and now I have the same 4.6:1 gear ratio as the stock Trex 500! Thanks for bringing that up man, I probably wouldn't have given it a second thought! Scale blades are back on, and hoping for a flight tomorrow!
 

PsyBorg

Wake up! Time to fly!
#94
Cool!! I am glad that sparked a helpful thought. Seems to me I remember ratios nearing 6:1 back when I was actively learning CP heli set ups for some. More then likely that was 3d not scale like you are flying though.
 

F106DeltaDart

Well-known member
#95
Cool!! I am glad that sparked a helpful thought. Seems to me I remember ratios nearing 6:1 back when I was actively learning CP heli set ups for some. More then likely that was 3d not scale like you are flying though.
Thanks again for helping me notice that! After I got back from work today, I took the Apache out and got it spooled up and... SHE FLIES!! No more problems with tail authority at all. Did some basic hover work and slow forward flight with no issues at all. Next time its off to the RC field with a fully charged battery to start messing around with forward flight:D.

As for tail ratio, its mostly dependent on main rotor vs. tail rotor diameter, so it can be pretty varied for different machines. A real Bell Jetranger or 407 has a ratio of about 6:1 as you said.
 

PsyBorg

Wake up! Time to fly!
#96
Well I did my part not get to gettin on yers and post some video!!! :applause: Glad yer good to fly now mate. Can't wait to see this baby in the air.
 

F106DeltaDart

Well-known member
#97
Well I did my part not get to gettin on yers and post some video!!! :applause: Glad yer good to fly now mate. Can't wait to see this baby in the air.
Hoping to get a video soon, maybe tomorrow if weather cooperates. Unfortunately, its supposed to be pouring rain for most of today.
 

F106DeltaDart

Well-known member
#98
Video of today's flight is up! Was really cutting things close today. Even leaving work 30 min early, I only made it to the field about 20 min before sunset. I recorded 2 videos, the one below and a second flight with a walk around of the aircraft. And the second video only turned out to be about 3 seconds since my iPad ran out of space.. Hopefully I can get a longer video and more photos next time.


As for the flight, I do still need to make some adjustments. The cyclic is very sensitive, so it may seem a bit twitchy. Tried to do some hovering in front of the camera, but I hovered on the wrong side of the iPad.. Anyways, it is smooth and was plenty of control authority for scale flight. I flew 2 flights for a total of about 6 minutes with ample reserve. As for overall impressions, man it looks cool in the air! I can't wait to get things adjusted and go flying some more.