500 Size AH-64A Apache build

[DCORSAIR]

Got my piece made tonight. I found a piece of metal at work that was the same thickness ( or close enough) as the original piece. Marked it up using the original al as a template, drilled out the holes then cut and grinder it into shape. It’s a little bigger size wise but the holes are on mark. It’s also strong. So now I just need to uninstall the mechanics again and change out this piece. This is where I am glad I used hot glue to glue The wooden tail tube holder in. A little if alcohol and the glue will come right off.

Gravy

Looks like that will work, good idea on the hot glue, in fact that is something I need to purchase for my shop, I heard hot glue works great for certain things, will have to give it a try...

[PawPaw]

Hey F106 and Gravy....either one of y’all do anything to the LG springs? Seem pretty weak.

[F106DeltaDart]

Hey F106 and Gravy....either one of y’all do anything to the LG springs? Seem pretty weak.

I just left them stock, but they are definitely on the weak side. They sit fully compressed on the ground.

[PawPaw]

Yeah, I’m thinking I will either find a stiffer spring or try putting a short plug in the strut to firm them up. Depends on how tight those grub screws are in the stop slot...aluminum and steel don’t mix well.

[Gravythe clown]

I left them stock. I found on the 700 it was better for them to be weak and compress. It definitely helps in the what I call danger zone. The time between fully siting on the ground up until both wheels in the air.

Gravy

[PawPaw]

I just plan to firm them up enough to keep the stop screw from bottoming out in the slot when sitting under its own weight. Just a few mm’s will do the trick I think. Not gonna risk stripping out the alum threads removing that steel grub screw, ‘tho.

[Gravythe clown]

Pawpaw take a really good look at the tail transition piece. After making my metal replacement for the control rod setup, I noticed a bunch of heat today after a test run up. Don’t like how any of that is setup. So I replaced the whole pulley setup with 4 bearing. What a difference that made. The whole tail drive is like silky smooth now.
However every since I have put the mechanics into the Apache and tried to fly it, the tail is uncontrollable. Just not sure what the deal is now. It flew great when I was first setting up the mechanics but now it just won’t stop waging,

Sometimes I just feel as though I’m not meant to fly this bird.

Gravy

[PawPaw]

Maybe it’s my perspective of the pic, but looks like the belt is in contact with both sides of the lower bearing and is getting pinched between the upper pulley? I’m not as far along as you, but I just ran my mechs up to 1700 for a few minutes and my tail just gets lukewarm. Feels like it’s the belt, not the pulley. What 4 blade tail unit are you using? I bought a Chinese one off Ebay and still not sure if I can even use it....blades don’t track 100%....and will prob need to fab new links if I don’t trash it first.

[Gravythe clown]

Yeah it’s prospective. There is a nice gap between the top (entering) belt and the bottom (returning belt bearings). The whole drive system is very smooth now, where in the past it was always tight.

took extra pics but really hard to see the gap in the pic but it’s there and about 2mm.

just checked my tail control linkage travel free from servo. And it’s smooth. My servo is one I’ve used (same brand and model number DS525M 333hz 1520 pulse) for my cobra. Also I flew several flight with the mechanics before first flight in the Apache fuse. the tail was dialed in with my gyro setting at about 65% (heading hold). Now it’s still not controllable at 100%.
im going to try and change the servo out first, other than that I’m not sure what else to check, I’ve going through the setting a dozen times.

Gravy

[PawPaw]

Sounds suspiciously like the fuse tail fin is blocking the airflow, but wouldn’t think it would that much. Are you using the brass tail drive gear that came in the kit? I remember F106 had tail holding issues and he figured out he was using the wrong gear.

[F106DeltaDart]

Sounds suspiciously like the fuse tail fin is blocking the airflow, but wouldn’t think it would that much. Are you using the brass tail drive gear that came in the kit? I remember F106 had tail holding issues and he figured out he was using the wrong gear.

There is definitely an issue with tail blockage on this particular airframe. I’ve always had tail authority issues with this bird and have tried everything in the book to minimize them, but I still regularly have tail issues flying in wind. No oscillations though, just loss of tail rotor effectiveness (LTE).

The first issue I had was the tail pinion. I ran a different tail drive pinion (one that came with my torque tube conversion), and I couldn’t even hover without the tail blowing out. The one included with the kit was a lower tooth count and provided more tail RPM, and was enough for successful hovers. I ended up slowly increasing head speed all the way to 1900rpm to get enough authority for basic maneuvering.

The second issue that I had was tail travel. The original tail I was using (made by CNChelicopter) had much more limited travel than a normal tail. I modified it and switched to another much stronger servo (BK-7005HV). I also switched to the largest tail blade that I could find that still provided tail clearance. Again, all this improved things, but I still experienced LTE even in light winds.

The next thing I tried was switching tail rotation direction, and making my own cascade tail rotor from 2 stock Trex 500 tail rotors. For efficiency, the forward-most tail blades should rotate up into the rotor wash. It’s not a huge efficiency gain, but I was looking for anything that I could get. The custom made tail allowed for a full +/- 45 deg travel on the tail, which also helped.

After all of this effort, I can fly without issues in very low wind (up to ~7 mph). In higher winds, a quartering tailwind or a direct crosswind can still cause LTE. With some minor effort, it’s easy to recover from this. If the tail blows out, reduce collective and get some forward speed. It will lock back in quickly when power is reduced. However, predicting where it will happen gets difficult in more wind. I’ve had it happen flying figure 8s in 15mph when it gets at just the right spot and speed. Hopefully this helps a bit, but it still isn’t exactly a solution. I still think the model needs a higher tail ratio but I’m out of ideas from simple changes to make.

[Gravythe clown]

Yeah F106 switched to Torque tube, I’m still belt drive.
yes I’m using the brass gear. Alas I’m now having this issue with mechanics outside of fuse. So at this point it’s fully a mechanical issue.
I just pulled out the whole tail drive system from the main frame back.
the belt is supper smooth now, the control rod from the servo all the way to the tail control arm is smooth.now now any tightness left is the pitch control on the tail shaft and the blade grips.
so I’m piercing together a new tail section to try.

I also ordered new aluminum pulley shafts as I found a crack on the plastic one.

I’ll update after some more testing.

Gravy

[F106DeltaDart]

Yeah F106 switched to Torque tube, I’m still belt drive.
yes I’m using the brass gear. Alas I’m now having this issue with mechanics outside of fuse. So at this point it’s fully a mechanical issue.
I just pulled out the whole tail drive system from the main frame back.
the belt is supper smooth now, the control rod from the servo all the way to the tail control arm is smooth.now now any tightness left is the pitch control on the tail shaft and the blade grips.
so I’m piercing together a new tail section to try.

I also ordered new aluminum pulley shafts as I found a crack on the plastic one.

I’ll update after some more testing.

Gravy

I might still have the original belt unit that came with mine if you need it.

[PawPaw]

If I read everything correctly, it flew well before you modified the tail transition unit with the added bearings?

[Gravythe clown]

Yes she flew. Mechs only on 4s, 900kv with 14t pinion.
I’m back to my standard gyro settings. Things are looking up.

yes it’s low rpm but it was only to test. After trying to fly in the fuse and having loss of power I decided to go back to the 900kv and use 6s with the 14T pinion. I tested it yesterday before all my other findings and it still had power issues but now my motor and ESC were warm to hot.

now that I got all my drive issues resolved and have no power issues, I’m going to go back to the 1210kv with the 16T pinion on 4s. She flew good with this setup and had plenty of power before I started having tail issues. And she was just sipping power, coming down cool both motor and esc.

so now I just need to wait for the née tail shafts and pieces. Then I’ll fly her again as Mech only a few more times. After that I’ll stuff the bird and say a few hail Marys.

Gravy

[Gravythe clown]

If I read everything correctly, it flew well before you modified the tail transition unit with the added bearings?

yes but then the triangle control rod piece started to act up as the mount hole got oblong. This started all the tail control issues.

my guess is that because I changed out for a metal triangle piece that really brought to life the issue with the pulley section. To me it’s just a bad design. That pulley should ride free on its shaft, not be the shaft that the triangle piece screws onto.

but I’m really happy now with my bee set up and honestly it’s never felt smoother. The whole drive assemble is just tits right now.

gravy

[DCORSAIR]

I'm trying to figure out your last paragraph, I think it contains some spelling errors??

[PawPaw]

The tail pushrod control setup could definitely be engineered better. I like your bearing shaft solution. Looks like I will be following F106’s lead and fab my own 4 blade tail hub...way too much vibration with this Chinese hub.

[Gravythe clown]

Yeah That are hit and miss. The one on my cobra is smooth, the Apache needed some work, and the black hawk I have not spooled up yet to see.
I did hover my mechs last night with the 1210kv motor and 16T pinion reinstalled. Hovered no more than 2' off the deck running 1800 rpm for 3 minutes on a 5000 30C 4s pack. After the 3 minutes my Pack was at 86% and both motor and ESC were cool to warm.
Now I just wait for new tail shafts and pitch control to come in so I can hopefully wrap this bird up.

Gravy

[PawPaw]

What’s the latest, Gravy? Suspense is killing me.