microdon2

My Feedback: (47)

Proline - I add flooring behind the stock blindnuts to secure the Dubro gear into. The Dubro gear is strong, and also flexes (as you said) - VERY forgiving. I still don't understand why Great Planes continues to make split gear and an in-line four bolt config, both of which are inherently weak. The Dubro gear setup does add a little weight, but I must think it's worth it, and it allows me to fly on a pretty rough field, which the stock gear could not handle. I'm trying to attach some pics but can't seem to see how to do it. Anyone know how?

proline1000

So just to confirm... You do mount the Dubro gear rear of the stock config. And can you tell me a dimension of how far back? This puts the wheels on the Dubro where the stock gear would put them? Thanks!

proline1000

Can anyone comment on using dual elevator servos? I am on the build and am deciding on using 1 or 2 elevator servos. I have servos available to do 2 servo set up. Also how do you program radio for 2 elevator servo set up? Can you use a Y harness and does the require a reversing lead? Thanks?

ahicks

My Feedback: (2)

Re: dual elev. servos. It's a matter of balance/CG? You install the engine and gas tank, install the servos in the wing w/linkages, basically install everything there aren't a lot of options on when installing. Then you assemble the plane (w/cowl, prop, and spinner) for a balancing session. This is where you see what needs to go where to keep the plane as light as possible, to balance without ballast. Decisions regarding dual elev servos vs. one, pull-pull elevevator vs. tail mount, receiver, ign. module, and battery placement, etc.

If you decide to go with dual elevator servos, they're set up exactly as you would when using dual aileron servos (using 2 channels slaved together), for all the same reasons. If that's not possible, then you do what you need to do, which might include the use of a Y harness.

wjcalhoun

Jim
I build my R70 with dual aft mounted elevator servos; if you search my posts on this thread, you will find some pictures of the structure you will need to add to support the forces generated by the servos. For me, i was not willing to trust the wheel collar solution in the book, which appears to be a kludge to me. However, others have had no problems with that setup, so it is a personal choice. As Al states, ,CG rules in placing components. If you will be using a gas engine (DLE20 for example), your bird will naturally tend to come out nose heavy, and therefore will tolerate the weight of elevator servos aft. OTOH, if you use a light 0.60 glow engine, it may not be possible to put servos there and still balance the plane.

Your radio should be able to slave two channels together; you will need two pairs, one for ailerons and one for elevators. Futabas use the 'ailevator' setup to get the two elevator channels working properly. I don't know about other brands. Using two channels lets you independently set the subtrims to zero your control surfaces, and independently set the end points to ensure that your throws are equal. Of course, set it up mechanically as best you can FIRST, and then use radio programming features to fine tune.

Bill

proline1000

Can you advise whether i will need a reverser in the Y harness? If so is that a bad idea? Another fail point? Thx!

proline1000

great thx. Will i need to add support to the servo tray even if i just use 2 servos? Thx

microdon2

My Feedback: (47)

Proline - the center of the Dubro gears is 3" back from the center of the stock blind nuts. To create the new floor I first cut a large access hole in the flooring in the fuel tank compartment - maybe 1 1/2 by 2 1/12" - needed to provide working access to install the flooring and the nuts. Then add a piece of 3/16th ply - 3 1/4 x 3" - cut in half length-wise to fit in and exactly fill the open floor section just after of the stock gear. The wood should just fit into the sidewalls of that flooring compartment. Then 30 min epoxy the two halves to secure it in place. Drill the four bolt-holes in the Dubro gear in a 4-corner config (not straight line), the hold that in place to mark locations for bolt holds in the new flooring. Then install blind nuts (this can be a bit tricky - I use a magnetized Philips head to insert the nut and hold it as I hammer-tap it in place, just enough to hold itself while I screw in the bolt). Tighten the bolt to complete pulling the blind nut down snug, then use more 30 min epoxy to secure the blind nuts from the inside (and use some vasoline on the nut to keep it clean.) Again, it does add some weight. But this setup has allowed me to fly on a very rough field and also saved me on more than a few rough landings (not so much, these days). I do use this setup on all four of my Revolvers (2 70", 2 59"). Not sure yet what I'm going to use on the 90" (whenever that happens), as I believe this is the largest Dubro makes. Maybe carbon fiber? btw - I've never had a problem with CG - just move the battery to where-ever it's needed.

Before installation I spray-paint the gear with fuel-proof white (from TH) - about 5 coats, as each is thin. When dry I cover with three different color trim - whatever matches the plane. Wrap the trim around the front of the gear, so that it does not pull off. Pics attached.

proline1000

great info and thx for all the detail and pics! I posted my aluminum beef up on last page i guess iwill modify to accomodate the dubro. Thx again!

ahicks

My Feedback: (2)

Re: the "reverser", consider how you mount your servos? If you mount them to allow the arm pointed up on both sides, vs. mounting them to allow one arm up and the other down?

proline1000

Contining on with the build I have another question please. I am using 4-40 rods for elev/rudder and find that the rods bind/stick quite a bit in the plastic guides. Do they need to be changed out and if so can anyone tell me correct size i/d for tube? Thanks much!

mach2

My Feedback: (5)

You're jumping rather quickly from question to question, so it may be a little hard for guys to keep up. It looked like a question or two had been answered before you asked, so try and make sure you read these guy's answers thoroughly to get the best out of them. The guys on here have a lot of good stuff that helps, but they can get worn out quickly by answering the same question multiple times (I'm sure I've worn some guys out myself). I'm not trying to be a dick, but figured I'd throw that out there so someone else doesn't have to.

On that note, I'll try and clarify something I think got confused. You asked about reinforcing the servo tray. Bill was talking about building servo mounts while doing dual AFT elevator servos (putting servos in the side of the fuse, usually somewhere near the leading edge of the horizontal stab). So he makes sure they are nice and strong. Since you asked about running rods through the tubes in the fuse for the elevator, I'm assuming you are not doing dual aft servos. If you are putting your elevator servos in the stock servo tray you'll be fine. No need to reinforce that.

You didn't mention what you decided on for your elevator and rudder system. Are you going to use the way the manual recommends?

So, for your last question. You are obviously using rods through the tubes for at least your elevators. If you are going to do that, you'll probably need to use 2-56 rods which are supplied with the plane. Running through the tube, they are plenty stiff in my opinion, but you could definitely use some better connecting hardware in the 2-56 size. I used all the supplied hardware on my first two planes, but wont be doing that on my third because I dont think they would hold up in the long run. Which I'll mention that I used robart pin hinges on the rudder and elevators. Using the robart drill guide makes it much easier to make straight holes, but not absolutely necessary.

As for your landing gear, it looks to me like you have real good building/fabrication skills. If I were you, I'd run the stock landing gear because they look so much better on this plane than the Dubro gear, and I think your modification will hold up fine unless you are really going to give them a beating by landing hard in grass or something like that. With your questions and building skills, I think that whatever decisions you make while building this plane will good. I think you've got a pretty good handle on it, so don't drive yourself nuts. I end up over thinking things a lot because I'm a newbie (kind of) and I don't like slapping things together.

Good luck and be sure to post pictures and videos when she's done!
Jeremy

mach2

My Feedback: (5)

Oh, and for your reversing Y question. If you end up needing one because of the way your servos are mounted, then sure, by all means. It just really ends up depending on how you mount the servos. If your radio is capable of using a channel for each then you can do it without any kind of Y. For detailed info on that, jump on the section of the forum for the radios and you'll be able to find lots of guys on there that can help you out with your particular radio. Each manufacturer and their radios work slightly differently and have different capabilities, so it's hard for people in this thread to be able to quickly and easily help you since we all use different equipment. It can also get very lengthy to work through radio programming instructions on forums.

Jump in here and see if any of these are your manufacturer. http://www.rcuniverse.com/forum/radi...ct-support-52/
Or in here if your MFR isn't available in the support group above http://www.rcuniverse.com/forum/rc-r...vos-gyros-157/

Jeremy

proline1000

Excellent and thanks!

Stone17

Yesterday at Fort Bend Flying Field, The throttle link broke on my 3rd flight of the day. I was coming in for a landing and I could not throttle back. She was stuck at Full throttle.
The whole flight time was about 30 min until she ran out of gas. I had my friend fly her for the last 15 min and he did the dead stick landing.

warbird72

My Feedback: (79)

WOW. My throttle servo mounting plate broke lose on the second flight to. Was stuck at almost half throttle. I thought my batteries were going to die before it finally quite. Fun fun! Glad you all got it down safely. Great job.

ahicks

My Feedback: (2)

Thus making the case for the use of transmitter controlled ignition cut off devices (opti switch) again.....

warbird72

My Feedback: (79)

That's hard to do with a glow engine lol. A fuel shut off now. That would work. I use opti kill in all my gassers. And if it has a mag on it. I hook a switch to a servo to kill it as well.

proline1000

Anyone? Thanks!

superduke1

I had my metal ball come out of the ball link on the throttle. I only noticed because I had to keep on adjusting my idle. I also think that the opto kill switches are a good idea on gas engines.

ahicks

My Feedback: (2)

Warbird -
Yup, suppose that would be an issue on a glow engine.

Proline, what are you using for power? It's obvious the 4-40 aren't going to work. Suggestions/ideas on how you might proceed dependent on info you haven't supplied? The popular mod of rear mounted elevator won't work out for you?

proline1000

I am using .80 rimfire. I plan to use 3 servos in servo tray. (2) elevator servos with 2-56 and (1) rudder servo with 4-40. I seems that the rudder rod guide tube is a bit snug for the 4-40 rod. I was curious as to anyones input on how to address this? Thanks!

wjcalhoun

Proline:
Think about setting up the rudder as a pull-pull, rather than a push rod. A 2-56 rod will have a lot of flex, and therefore a lot of imprecision controlling the rudder. If you are set on rod, think about a carbon fiber rod which is much stiffer, and use epoxy of jb-weld to attach fittings to the end of the carbon.

Also, aft mounted elevator servos are great; MUCH better than tray mounted elevator servos. You can use 2-56 hardware then, and cover the 2-56 rod with a carbon fiber tube, epoxied in place.

Check the build posts earlier in this thread.

BIll

proline1000

okay great ideas I have seen those options in threads i will revisit whole issue before i proceed. Thanks again for the input!

mach2

My Feedback: (5)

Looks like he's running the DLE20. So an opti-kill would have enabled him to kill it on his terms in a good location to set up for a landing. Plus, your focus has got to be worn down after flying a screaming Revolver for a half an hour. Opti-kills are a cheap bit of safety for everyone. Some flying fields require them. Luckily he had someone he could rely on to help him out.

Also, looks like a good field for the incident. Nice and roomy for a dead stick