Thread Tools
This thread is privately moderated by farquward, who may elect to delete unwanted replies.
Aug 26, 2016, 06:06 PM
Today is a good day to fly
farquward's Avatar
Thread OP
Discussion

MD500D revisited


So some discussion has been going on between Jim and I about stuffing a 230S into an MD500 shell. It will work. Here's a CF frame w/servos in the shell and the pictures that have blue tape show what I will be cutting to allow linkage clearance. To secure the frame to the shell, I think I'll use some 1/16th " ply attached where the LG would and screwed to the ply in the shell. Also, I made the tail feathers from old credit cards and the vertical fin from a 200 SRX (when that was the mechanics) and will most likely do the same for this one as it's much lighter than the included pieces.

8/27/16. Later today I'll add some discussion Jim and I have had. Anyone else interested in this, please feel free to join in.

Ok, taking the easy way on this, just visit the Scale Modeling Thread in micro heli's and go to post # 1443, it's on page 97 and it's in red print, can't miss it. Thanks Jim! rcnutrc (Tim) has joined in along with Jon_PDX and nagas. We'll get this sorted and flying in no time.

8/28/16. One idea that keeps popping up is lowering the frame to prevent cutting the dog house. It just occurred to me why this isn't a good idea. Unless you're making a custom main shaft, the rotor disk will be too low and that will result in very bad things happening when the cyclic gets busy. Due to our on going re- model, I get very little hobby time. My work shop is a disaster since we've needed the space for temp storage. Yeah, you got some cheese for my w(h)ine?

So far the biggest problem I'm having with this is my donor 230 isn't playing nicely and may be going back to HH. Don't want to use my other one as that's my daily flyer/trainer for now so the other has to be sorted before it's flow, let alone used in a scale project.

9/4/16. This project will most likely be the first of this winters. It should be the easiest and I'd like to get it flying as it's been in the hanger the longest. With it being already finished and looking good, no scale details like panel lines or rivets will be added. Not so much a weight consideration, but a time allowance. The UH-1E project is going to be detailed in as much as the size of the bird allows.

As for the donor, I'll add another wheel weight and see what that does, trim flights got me nowhere. I'm also skeptical of the CF frame. As the 230 seems sensitive to vibration, so much so that even tightening the battery strap can cause issues, what would a stiff frame do? As the servos are in the same locations as the stock, I'll just use it. No need to reinvent the wheel or add drama to the build.

Looks like a standoff, who'll be the first brave soul to attempt this.

9/11/2016. Our flag is at half-mast. God bless America!

9/18/2016. Jim is leading the way and has done some nice work with the shell, looking forward to seeing it finished. For me, the biggest problem seems the tail motor wiring. It's just long enough, which means trying to plug them in when in the shell could be challenging, to say the least. Sure, it's easy enough to make them longer, but at what cost? Voltage drop applies here, so if you extend the wires enough to allow connection, they would need to be a bigger AWG to carry the same current. Then there's the problem of getting the boom back into the frame as the 230S has the wires come out the bottom of the boom. Easy enough when it's pod and boom, but just might be an obstacle for this build. I haven't looked at this since I stuck the CF frame in the shell, so may I'm worrying too much.

9/28/2016. I did a frame replacement and rebuild on a 230S and while at it, I noticed the differences between the stock and CF frames. Small differences, but if you're considering this I recommend using the CF frame. The big difference is how much tighter the elevator servo sits in, eliminating the need to cut a clearance for it. Another benefit, the boom can be mounted to the frame rather than making adaptors. I've installed the MH rotor hub, blade grips and swash plate and will start cutting the shell for linkage clearance today along with transferring the RX, motor and ESC to the new frame. Should be ready for a test flight tomorrow.

Transferred the goodies to the CF frame and cut slots in the shell. Just need to fine tune the slots and bolt it down. Should have a maiden flight report tomorrow, with any luck. Winds are forecast 30/40 mph .

9/30/2016 Hit a mental road block last night. So I set it aside and went in to make dinner, my take on a "spaghetti western" My home made pasta and marinara sauce with buffalo meat. I need a small hole aft on the port side to allow tightening of the boom clamp, it's alignment is critical as the bolt is recessed in the frame already. So with fresh mind and some good suggestions I'll take another look. Decided to use the tail feathers from the 200 build, they're done and painted and with the RHK tail motor mount, it was an easy fit. The linkage now has good clearance so it's down to some minor fitting issues.

10/1/2016. Problem solved as far as the clamp/tail boom access. (Thanks Jon) By removing the assembly from the frame, cutting a bamboo stick to 2 5/32" and dipping one end in paint. Put the frame back into the shell and re-check alignment. Reach in thru the window with a long curved hemostat and while holding the frame secure, slide the bamboo so it marks the inside of the shell. Remove the frame and set aside. Hold a flashlight to shine inside and mark the outside. Drill. Re-install the assembly to the frame, slide back in and cross your fingers.
Made a short extension for the tail motor. So now we're ready to for final assembly. I started by prepping the tail boom, slid the wires in and got the male ends thru the end. Install the extensions now. Here's where it gets tricky. You have to hold your tongue so it's just touching your nose, close your left eye while humming the USMC anthem, all 4 verses, this is important. I tried to get the connectors thru the clamp, and found it better to remove the extensions, remove the clamp from the frame, get the wires thru and reinstall the clamp and wire extensions. Also had to loosen the tail motor mount and pull the motor back some to get the boom into the clamp. That went, um, not so well but I did manage to get the boom seated. Now you need to get the slack out so the tail motor and mount will return to their mounting position. This was going pretty good, slow but good. Then as the last of the slack was out, the dad gum extensions pulled off. To say this is challenging is an understatement, but I'll persevere and conquer.
Starting fresh this morning, took a couple of pictures showing the rails and ty-wraps I'll use to secure the frame to the shell. Next, to re-connect the tail motor wires, tie the frame down, install tail feathers and maiden.

Final assembly is done. Radio re-check and all's working as it should. I'm concerned about how tail heavy it is even with 3/4oz added to the nose. Honestly it could most likely use another 3/4oz to balance. Another issue is tail rotor clearance, with the boom centered it hits the shell so I shifted it over a bit to clear.

Went out front and spooled up, not happy right now, there's some issues to work out. It's still tail heavy so that has got to be fixed. The sidewalk is sloped to the street so it's not sitting level, 230S's don't like that. The wind is less than ideal for a good shake down, so I'll wait for better conditions.

10/11/2016, So after much thought and reading the back and forth in the scale thread, the 200 SRX w/4 blade head is going back in. My thought is: the 200 is much lighter than the 230 and has the same motor/battery. Mine is geared to the moon and with the added lift of the 4 blade head, I feel it flew better. The pit in the olive was the short flights and going LVC. In hind sight, the batteries I was using were cheap no-name and didn't even have a C rating. I had experienced rather short life with them before they puffed up like a nickel balloon. While they served well enough under a light load, I think they were really the weak link. With my current stock of batteries, I think the out come will be much different. With that said, last night I put the 200/4 blade setup back together and did a test. It flew well, with a wobble, but I have a brand new set of Bocca Bearings and a new frame, all ready to go. The bearings in it now have a boat load of flights, a couple of crashes and are just shot and the Bocca's were in my inventory. If this works as I think it will, a new, higher mAh battery with a C rating of 45 will find it's way into the rotation for this project.
The 230 needed a massive amount of weight in the nose while the 200 balanced out w/o ant added weight, if just a touch tail heavy, The bigger battery should correct that and also help flight performance.

10/12/2016. Getting some good feed-back on the scale modders thread, right now the best idea is a set of Lynx 150mm blades for the 4 blade head. This is the lowest cost option right now and I've already tapped into my 450 build monies. I'd like to see this one flying well and it's close to that, just not quite there yet. The second option is a 250 CFX motor/ESC installed in the 230S. While this would most likely be the better option, the 2 blade head isn't cutting it for me and I haven't seen a 4 blade head for the 230. Come on Lynx, I'd buy one.

10/13/2016. New plan. 300X motor, 230S ESC, 200 SRX, 13/104 gears, RHK 4 blade head w/XXXmm blades and a 1200mAh 3S 45C battery. This should work, and as they say.......it looks good on paper.

10/14/2016. My conversion for inches to mm wasn't right. So much for the old memory. Now 180mm blades for the Blade 180CFX are the idea. These are 30mm longer than those on the 4bld head. Got 4 of those on the way, along with a Scorpion motor, Lynx 12 & 13t pinion gears along with an ESC for the 230S. This is in the great American tradition of stuffing the biggest motor in the smallest possible frame, kind of like stuffing a big block Chevy in a Vega. If this doesn't work in the 500 shell, it will be one fast 200 SRX!

10/16/2016. Destroyed a good 200 tail motor, got frustrated and set everything aside. It gave me time to think about the future of this build. The over powered, over geared 200 with a big battery and bigger rotor disk should fly this thing, no problem. However, the weak point is the DD tail, be it 200 or 230. A DD tail is much heavier than the belt drive of the TRex 250 it was built for, and getting the motor on and wired is, difficult to say the least. Also consider the wiring issue I'm considering running the TM wires outside the boom, just don't like the idea much. That would require compromising the motor mount, weakening it.

So looking at my fleet, there's the 300X and CFX. They're kind of big, but could be squeezed in I think. The new Scorpion motor would drop in too.

What ever happens, I'm going to get this one flying as it should before moving on to anything else.

Making the adjustment to ordering everything off the web, all I can say is I miss the convenience of having a LHS within walking distance.

10/20/2016. The recent rain highlighted a weakness in our chicken pen and had to be addressed. So we built a shelter for the feeder and brought in 1.3 cubic yards of pea gravel, problem(s) solved. The wife painted the feeder shelter yesterday and I'll do the roof today.

Last night I took the new motor, mount and frame and dry fit them. Totally do-able, just need to trim the motor shaft a tad. The Lynx 180mm blades are just a couple mm shorter than the stock blades, and lighter. As I said, the RHK 4 blade length was about 1.25" shorter. Might get to set the motor and ESC today, we'll see. So all we're waiting on now is the tail motor. Saved the pieces that were cut out to allow clearance for the 230, those will get glued back in, a little filler to finish then maybe paint, if I can match the color.

10/21/2016. So I was dry fitting the power train last night and noticed the center lower frame cross brace is problematic, it will have to be notched, enough that the thru-bolt will no longer be used. I think a suitable spacer can be made and relocated further aft to strengthen the area. Marked the shaft for a flat and cutting, will go to the hardware store for a new cutoff wheel for my dremel tool. The holes in the Lynx rotors also need to be drilled out ever so slightly, but they come very well matched. I'll set them up on the drill press to drill.

10/23/2016. Chores done, got to fly this am, so I'll head out to the shop and start to work on the new motor and frame. The shaft will need to be trimmed about 3/16" and a small flat for the set screw ground in. Both easily done with a cut off wheel. The motor will get wrapped with a towel then placed in a plastic bag to prevent any filings from entering the motor. The frame will get a radius ground out of the center bottom frame support for motor clearance. I'll use a short bit from a broken LG, drilled to replace the brace, far enough aft of the motor.

10/25/2016. Finished all frame mods yesterday, the top underside cross brace needed clearance too. Did some bench testing as the rains are here. The 230 ESC got warm as did the JST connector. Both motors spin the right way. Drained the battery really quick. So for this to get a test flight, the JST needs to be upgraded, a bigger battery and I'll check the gear mesh again as it felt tight after installing everything in the shell. There's just enough funds from the 450 project for these updates, might as well go for it now.

11/15/2017. This little guy has been on the back burner, and it's off. Decided to resurrect this and try again, and it's back to plan A, with mods so let's call it plan A1. So to recap, a 200 SRX will supply the frame. servos and Rx, a 230 S will provide the tail boom and tail motor while a 250 CFX will donate an ESC to feed a 300X motor. Gearing will be 12/104 spinning a RHK 4 blade head w/Lynx 180mm blades. Sounds like a plan, no?
Last edited by farquward; Nov 15, 2017 at 11:06 AM.
Sign up now
to remove ads between posts


Quick Reply
Message:
Thread Tools