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500 Size AH-64A Apache build

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  • Yeah I would have expected yours to be more than just 0.4 lbs. with everything you have added.
    I definitely think the TT drive is not helping your gears from stripping. But I also wonder if lower KV lower pinion and higher voltage isn’t amplifying the TT torque issue
    Your setup is not working as hard as mine which will allow it to spin up fast and with more available torque, where mine would stall out quicker, rather than push through.

    it will be interesting to see where pawpaw’s shacks out at. He’s using same power set up a you but I believe he’s keeping belt drive.

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    • I’m belt drive. So far, I haven’t found any issues with my stock setup and F106 designed 4 blade X tail. My flying style has been ultra conservative..read that as CAUTIOUS...as I test and gain confidence in the method I used to attach the tail belt pulley to the longer shaft needed for the 4 blade setup. Issues may show up when I fly it harder but right now I’m predicting it will be ok. Also, I do fly with FBL governor mode instead of ESC governor which may show some difference.

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      • From all of the discussions around weight, I realized that the only time I ever measured flight weight for the Apache was on an old (and very problematic) kitchen scale. I ended up throwing it out a year later as it was more or less worthless. So, I got out a newer scale to hopefully get a more accurate handle on the weight. All up, it came in at 9.5 lbs, which explains a lot. Likely both the tail rotor issue, and the gear stripping. In other words, keep your Apaches light! This weekend I’m going to try some larger chord RT 430mm blades if weather holds. Their wider chord will hopefully take the weight better and create more lift for less torque.

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        • Holy cow, that’s a heavy bird. Yeah your thicker cord blades hopefully help.

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          • Hello gentlemen,
            I have been reading this thread to get familiar with the building of the Apache. I recently bought one (Not the RC Aerodyne scale fuselage kit) but a "copy" of it? who knows. Looks familiar but it has some unscaled looking bumps to fit the main gear. I wish I had done research on it before pulling the trigger. Unfortunately it didn't come with the side frames that lower the tail boom and raised tail kit. I bought everything (Torque tube) I needed to try and build it but one of the parts (raise tail) will not work with the Apache. The tail part is meant for theUH-60 500 Scale & AH-1 500 Scale. I know F106DeltaDart used a Torque tube drive setup? Can you point me to the one you used? Or even the tail conversion. Any help is appreciated. Thanks guys. Happy flying/ Building.

            This one looks similar to the one I bought. I found this picture on google.

            Click image for larger version

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            • Unfortunately, the gearbox setup I used is discontinued. Used to be made by a company called smartmodel: http://www.electric-rc-helicopter.co...ive-t5433.html. I had to mode the side panels to get the higher angle required for the Apache tail.

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              • F106DeltaDart, thanks for getting back to me. I'll just wait and hopefully someone starts making more or make my own.

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                • Try PKM on Facebook. Be ready, they aren’t cheap.
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                  • Right on! thanks man

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                    • I would like to show some photos of our 500 AH-64 conversion build. Any questions. let me know. This a Belt Drive tail unit with 4 bladed tail rotor from Bangood China, Align 500 4 blade Scale main Head, Torq Mini Servos with Castle 80A ESC, Bavarian Demon 3X, Scorpion HK3226-1400KV Motor and MKS HV9780 Tail Rudder.
                      Attached Files

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                      • Which Torq servo did you use for the tail?
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                        • I used our MKS HV9780 Mini Tail Rudder servo Alpha.

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                          • Well, I think I may have finally nailed down why I've been fighting tail issues with my Apache for so long. I finally took it apart and got the ratios of the stock gearing. 112T Autorotation gear and a 31T tail pinion makes for a 1:3.6 Main/Tail ratio. I suspect the reason why the pilots using the stock belt drive have not seen these issues, is that the front drive pulley is being used as a a 2nd stage gearing to get the tail ratio higher, and may have a higher tooth count than the tail pulley. I can't confirm this, as I got rid of the belt drive parts years ago. But with a 1:3.6 ratio, everything I've seen makes perfect sense.

                            This leaves me with 3 options:
                            - Convert back to belt drive and find the original drive pulley
                            - Find a different front tail drive pinion (Ideally 25-22T for ~5:1 ratio) - Runs Risk of over-stressing autorotation gear
                            - Direct motor drive to torque tube input - e.i. miniquad motor to independly drive tail shaft.

                            I did some quick searching for pinions knowing that the stock trex 500 Auto gear is Mod 0.6, and found some Tamiya truck pinions that might work.. https://www.amainhobbies.com/search?...+0.6mod+pinion

                            For now, that seems like the easiest change to make. I'll start with the 25T and decrease from there if needed to keep stress low on the autorotation gear. Should receive the gears this weekend.

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                            • Over the past 3 months I have flown each of the new tail pinions with next to no difference in tail performance. This left me incredibly confused, and I had spent a while trying to experiment to see if there was a weird aerodynamic issue going on. Then yesterday I finally had the breakthrough that I needed.

                              For a while, I have had a tail servo (MKS X6 HBL599) siting around that was planned for a Roban EC135. I never pulled the trigger on it, so it was just sitting around unopened. I figured just to eliminate the servo as a potential issue, that I'd try installing it. The 22T tail pinion was also installed. I figured this would do nothing. I already had a stupidly oversized tail servo.

                              Original servo: MKS DS8910A+, 6V Stall torque of 2.6 kg-cm (I use this in all my other 500 helis)
                              1st Upgrade servo: BK 7005HV, 6V Stall torque of 8.4 kg-cm (This was in the Apache for the last several years)
                              2nd Upgrade servo: MKS HBL599, 6V Stall torque of 30 kg-cm (The nuclear option!)

                              I took the mechanics out for some flights and was shocked to find excellent tail response! No more slow, faltering pedal turns. I guess that the cascade tail really requires a ton of torque. I'm sure I could get away with less, but I'm certainly not messing with it now! Next step is to try it with the fuselage installed, and in a bit of wind.

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                              • A few photos from flying this morning. First time out trying the new tail servo in some heavy winds. It performed perfectly! Tail held rock solid. I think that I have finally cracked the code to making this an everyday flyer!

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                                • Looks awesome F106…great job!

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                                  • Yes, looks great Delta, my 700 Apache does those pedal turns, the servo in it now has 111oz of torque, wonder if I stepped it up to more torque it would be better for the cascading tail??

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                                    • Originally posted by DCORSAIR View Post
                                      Yes, looks great Delta, my 700 Apache does those pedal turns, the servo in it now has 111oz of torque, wonder if I stepped it up to more torque it would be better for the cascading tail??
                                      It certainly can’t hurt. I think a combination of a few things helped solve my issue.

                                      1. Eliminated the flexible Sullivan golden rod I was using for tail control. Built a rigid bellcrank type system instead.
                                      2. Sped up the tail RPM. Went from a 26 to a 21T pinion for driving the tail.
                                      3. Went to the nuclear option tail servo (~500 oz-in torque)

                                      So I can’t say the tail servo alone solved it. But it certainly was the one that made the most immediate difference.

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                                      • A few photos from flying some afternoon air support with the Apache and HG Cougar MRAP.

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                                        • Dammit... got a whole operation going on!! Looks good!! Where's the MRAP from?

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