wjcalhoun

8pr

On the CG - get those twin elevator servos in aft! #1 The R70 flies better with the CG behind where the book suggests (YMMV), within limits, and #2 the aft servos do counterbalance the DLE20. I would have had to add lead to the tail without the two aft servos.

Many people suggest, and I agree, that the stuff that must be where it is - engine/muffler, rudder servo, elevator servos, aileron servos go in first; then do a test of the CG; that gives you the radio, switch(es), battery, and fuel tank to place depending on where you need mass. For me, I generally place the fuel tank first (of those 4 things), getting it as far back (toward the CG/wing tube) as possible to minimize CG changes during flight as fuel is depleted. Then its just a matter of counteracting any nose (or tail) heaviness; the radio receiver is trivial, but the battery carries mass, and I use miracle switches which have perceptible mass. My first R70 with an OS 1.20AX needed an ounce of lead on the FW to bring the CG to book. After 10-15 flights, I lost the lead.

The other thing to remember is that CG adjustments relate to torque acting on the CG - mass x distance. One ounce of weight 4 inches aft of the CG is (about) as good as 4 ounces 1 inch aft, etc. If you are really nose heavy (unlikely with dual aft elevator servos), it can be worth it to build a battery tray aft of the servo deck, so that your battery acts through a longer moment arm.

Downside of mounting mass far from the CG is, of course, that more centrifugal force is generated in spins and snaps etc, which is proportional to the square of the distance from CG. If you do need to mount a battery tray aft, make sure it is strong, and well tied into solid structure. Maneuvers generate 5-8g!.


Mike - gas stabilizer reduces oxidation of the fuel, and inhibits separation of the EtOH. Common brand is Sta-Bil (gotta love those marketers) at most auto parts shops.

Kit - I think your reinforcement is pretty much what Al does (ahicks); good photo



Bill

lopflyers

My Feedback: (12)

Got to love Bill, he can dissect this business like a frog in a science lab

JH313

Ahicks,

ahicks

My Feedback: (2)

Solder on clevis = an unthreaded metal clevis that must be soldered to a pushrod that's been cut to length? Junk, they break frequently, and I'm not talking about a failed solder joint.

I wouldn't use hardware that didn't meet 1/4 scale standards - if that makes any sense? The exception on the Rev 70 might be the control horns as the flight surfaces are not that big or heavy. I would not use any of the supplied pushrods, though I know some have.

And you do make a good point. My planes are flown hard. They're built right from the get go so I don't have to worry about doing that - so my advise may seem a little over the top to somebody going up and flying around a race track for a while, then landing? To that I say this plane is just SO capable, it begs to be beat on? Thinking Bill might agree...

BTW, quality 2 stroke oils contains additives that keep gasoline stabilized for years? It's part of the standards they have to meet for different certifications - and I'm going no further with that. There's a million strings with many more millions of responses already. "Stabilized" fuel sitting around in our toys and/or lawn equipment won't smell like turpentine for years. Unstabilized often will only go months.

Bills advise above (second paragragh, post #6865) for those not already building this way, needs to be reread and kept in mind for not just this build, but for any plane you're trying to keep as light as possible, with a CG placed properly, without the need for ballast. Place/install the "have to's" where they need to be, then move the rest of your stuff around to your best advantage. Screw those directions regarding this part of the build!

Kit, recognize you are using an angle extrusion where I bent a piece of sheet material. I think it's a great idea if you can find something that's as wide and as thin as what you've located? Mine has taken a terrific amount of abuse without trouble. It took a near wide open blast into the ground to remove it! Point being, as previously mentioned, not sure it's so important what is used to reinforce the joint, as much as the importance of doing SOMETHING similar to that?

And last, a very kind fellow RC'er has donated the landing gear I needed to me, and refused payment of any sort. Many thanks to him, and attempts to pay that kindness forward WILL be made. -Al

8.point.roll

ahicks:   Your very welcome, and I do understand on it taking a while to get a part from TH.  Waited 3 months for a part myself.  

flyboydale54

I have looked into the Power HD MG Servos myself. I was impressed at the torque for the price. Only thing that stopped me from buying them was the fact they are not programable. For me, I feel that if I can not program a digital servo, then I may as well stick to a cheaper analog servo. I did watch a few You Tube Videos on Power HD Servos. I did like the fact that when this person rated them, he had a jig set up that he kept piling large bolts into, thus determining the stall weight for the servo. He also had a centering indicator set up with it. The Power HD Servo did center well on most of them. Be careful and do the search, watch, and read on the Power HD model servos. They are not all created equal. Some models in fact will crap out at any time with a failure. There is also something about when the servos were manufactured and recommended to stay away from those models and date codes that are problematic.

I have used the Hitec 5625 and 5645's in a few models now and I like them. Worth what I paid for them with a discount for the multiple package deal. It was mentioned recently that they tend not to center well. I have not noticed this in my flying of the model though. They are in my Revolver 50cc Plane that has a DLE55 in it.

I moved the battery pack back from in front of the rudder servo to rear of the rudder servo and now I can at least land it within the length of the runway, most of the time.

I am not going to mess with anything until I send in the 9503 JR Radio. It mysteriously blew a fuse just before I was getting ready to fly it, then when I replaced the fuse, it worked RF wise, but no adjustments to anything can be made because it reverts back to the original settings programmed in before the fuse blew. It appears it corrupted the memory. I can not even change models to fly another plane. I can not even give myself more degrees of spoilers. I found after the CG moving rearward that the Revolver 50cc Plane only requires a touch of down elevator to fly level. I am going to make a battery shelf that will allow for small movements after I get the radio sent in and fixed. I only flew with this transmitter a few flights. It is still under warranty and I heard they will even fix this problem of corrupted memory after the warranty runs out. I experienced spuratic elevator and aileron movement too just before the fuse blew in the transmitter. One aileron servo moved and the other did not. One elevator servo moved and the other did not. It was a borrowed Spektrum 7010 receiver as I recall, and when my friend wiggled the wires going into the servo, they came back to life intermittently. After he pulled the cover off of it, I saw poor solder joints and someone left the flux on these solder joints, meaning someone had trouble with it before. I put in a new RX of a Spektrum AR-8000 and presto, everything worked well except for the corrupted memory issues in the transmitter. I just can not do any tweaks until I send in the transmitter.

I do not know if it voids the warranty replacing the 3 amp fuse in the transmitter, but I did and my friend got to find out that the memory has been corrupted in the transmitter. On one hand, I want to put the blown fuse back in the transmitter and mail it in for service, but if I do that, I would not be able to tell the service department the findings of the memory corruption my friend found when he tried to set it back up and give more throw on the spoilers.

wjcalhoun

Wow - that is an OLD post.

I tried Power HD DS-120M servos in my R70#1. Within 7 flights three of 5 had failed, two in flight, and one in preflight check. Fortunately, the failures were aileron and rudder in flight, so I did not lose the plane. Had it been an elevator servo, I may have lost her. I pulled them and replaced with Futaba S9452. Would probably have used Savox now if I had it to do over again; better specs, less money. Hitec 56xx would be fine, but are pretty slow now compared to competing brands like Savox.

Not slamming all Power HD servos, because their quality apparently differs dramatically depending on the exact model of the servo, but my experience with the 120M makes me not trust them at all. To save $15 on a servo and lose a plane is not good economy in my book.

JH313

So should I stick with the plastic clevis or buy Sullivan. Is it necessary to go to 4-40 pushrods? I am on a tight budget, which is why I am asking. Note, my servos are 485hb servos. Thanks.

Bennijiggs

I have stock size pushrods and stock plastic clevises on mine. 12-15 flights so far no issues. I may upgrade to the metal ones ad the 4-40 soon though just for piece of mind.

SigMan

My Feedback: (21)

dang ! i just received my cheap Power HD servos today for my R70...who wants them ? i paid 50 bucks for 4 shipped. i knew that was to cheap.

wjcalhoun

JH
2-56 hardware is generally OK.
You might try encasing the 2-56 rod with a carbon fiber tube. Rough up the rod with sandpaper or steel wool, and coat it with a light coat of 30 min epoxy. slide on a carbon fiber tube a bit shorter than the exposed span, and you will have a light, strong pushrod

ahicks

My Feedback: (2)

Regarding the Power HD servos, as mentioned, some of them have pretty good reputations. These are overkill, but I wouldn't be at all shy to use them? They are the only Power HD I'd use personally though. They're analog, meaning they aren't programmable (who cares?) and they aren't power hungry pigs that take huge power to run! They're perfect for planes you plan on beating on......

http://www.troybuiltmodels.com/items/HD-1501MG.html

Your call. Not going to say there are no better servos available. Only that I've been VERY lucky with carefully selected inexpensive (less than 15.00) servos, in many models, for a long time (hundreds and hundreds of flights!). Not flying in contests, or doing anything anyone would call precision flying. I'm a sport flyer, a 3D wannabee hack, but I have fun!! -Al

ahicks

My Feedback: (2)

Re: the 2-56, I love the idea of sliding carbon fiber over it, but that still leaves me with a choice of 2-56 clevises or ball links to work with, and those just seem wimpy to me. Could be I'm just used to working with the larger stuff, as I was flying 30cc planes before picking up on what the 20cc engines will do. 30cc planes getting pretty dusty lately....

I will say there is no way I would run the suggested pushrod setup on the elevators though - NO WAY!

flyboydale54

My question to you that say to mount the fuel tank backwards. When you pull a loop, where does the clunk in the tank go with a backward mounted fuel tank? With the fuel tank mounted backwards, where does the fuel tend to go? I think away from the pickup (clunk). Wouldn't this cause a problem?

8.point.roll

Count me in with @wjcalhoun and the Savox servos. As Bill said, price-performance is pretty tough to match, with performance including long-term usage/reliability.
I have the 251's in my R70 and the 254's on a H9 Pulse 60.

PDF

Hello all,
I'm in the process now of installing the CA hinges in the tail. I've never used CA hinges before but I'm going to on this especially since the ailerons are already done. The manual says center the hinges using a pin in the center then pull out the pin and close the gap on the leading edge and trailing edge of the control surfaces, lay flat and apply six drops of thin CA per hinge and leave set. My question here is if I push it together with no gap when I deflect the hinge will there be enough flex? I question myself because I saw a video on this site that showed they way to install CA hinges. It said center the hinges using pins,once installed pull the pins push the control surface tight and deflect the control surface beyond you max flex and apply 4 drops of CA per side of the hinge. Which is correct? Any advice would be appreciated.
Thanks,
Pat

8.point.roll

@flyboy: I do not understand why the need for a servo to be programmable??? I use a Futaba 10C transmitter and either HiTec, Futaba, or Savox servos.... all digital. (BTW, the Savox 251's are in my Revolver... have not finished build, but I think they are a great servo for this plane). Having the ability to set end-points, fail-safe, etc., with my radio, why is servo programming needed? Do you use an external programmer like the $90 one that HiTec sells?

Thank you for your advice and help.

-8pr

VictoryRoll

My Feedback: (2)

@PDF: I personally do not use CA hinges anymore. It's not that I have had failure myself, but on a hotrod like the Revolver, I would not risk it. Just my personal opinion. But, when I did use them (and if my memory serves me), I used the pin to keep the distance between the trailing edge (TE) and the leading edge (LE) of the control surface (i.e aileron), at a minimal distance while also keeping the hinge straight and not tilted. I would use two pins per hinge to keep the hinge straight and perpendicular to the surface. The width of a pin is fine for separation. I personally always glued one-side at a time. By gluing one side (and it certainly does not take a long time for thin CA to cure [PLEASE DO NOT USE ACCELERATOR as it makes the hinge brittle and it WILL break]), it allows you to work at a slower and more methodical pace, making sure that the hinges line up, are straight, etc. After that side cured, insert the hinges into the other edge/surface (ex. Aileron LE) and then put 5 or 6 drops in that (the opposite side you just did) side of the CA Hinge, let cure, remove pins and your done. Test hinges by pulling firmly on opposite sides of the hinges to see if any one of them is loose or pulls out in any manner. If so, put a few drops of CA on that (or both) side(s) and re-test.

You could (should) seal the surfaces by placing either "Blenderm" or clear MonoKote in the opening or space between the TE and the control surface-LE. This keeps any air from leaking in-between the gap in the two surfaces. Again, you can find the methods and instructions for sealing edges of control surfaces by searching on RCU.

I would also use the CA hinges that have a slot cut in the middle of the hinge that improves wicking of the CA down into the hinge and most importantly the wood.

Again, I do not use them and would not suggest using them on the Revolver if you plan on flying the plane to its potential. There are many on this board that could give you better instructions to help you and maybe a preferred (correct) method of gluing CA hinges, etc.

Best of Luck,

-VR

ahicks

My Feedback: (2)

I share Victory's hesitance to use CA hinges. I have had them fail, from fatigue, on older planes (second season maybe?) I've also had them delaminate just when used when used as a patch? If I can't trust them in a patch, I'm going to trust them to hold a control surface on? Nope...

If they're already installed, they're easily cut with a razor or sharp exacto along the hinge line. Once cut apart you would proceed as if they weren't there, installing a real hinge to either side of them or as necessary. Pre-installed CA hinges usually have so little glue on them anyway, the balsa to either side of an installed CA hinge is unaffected by whatever glue is holding that hinge in place.

Re: the programmable servos? Let's say you have a bigger model, and you've paired up a couple of them on your rudder. Invariably, they're not perfectly matched when it comes to centering, and with no other way to compensate, they'll need to be programed to match. Otherwise they buzz and suck power, maybe a lot of power, as they fight each other.

There may be other instances where you might benefit from programming, but I've never run across it. -Al

neilrether

Not that I condone using CA hinges on this plane, but I always cut a slit in the middle of my hinges to give another channel for the CA to wick into. I have purchased the brand of hinges that already have the slit, but I always add the slit if the hinges don't have it.

I thought I had beefed up my landing gear enough from the inside when I originally assembled the plane, but a couple of weekends ago it turned loose. The re-enforcement I had added did hold up, but the cheap plywood in the plane de-laminated from my added bracing. So, adding a new bottom plate and more internal re-enforcement from the bottom side, now that I can get to it. The original wood parts did not have wood to wood contact and the rubbery hot glue did not even span the gaps between the wood. For a dollars more work and wood, this would not be a problem.

Also need to remove more nose weight that I initially added trying to get the CG closer to where the manual called for. I know it's been said the plane lands better with the CG further back, but I intended on removing weight as I got more used to the plane. The jack rabbit landings finally caused the LG failure. I think I'll remove all of the extra nose weight now.

Neil

ahicks

My Feedback: (2)

*** The re-enforcement I had added did hold up, but the cheap plywood in the plane de-laminated from my added bracing.***

That's the lesson that needs to be learned here. Not only is the China ply brittle, it delaminates very easily.

Gluing to it, unless the glue joint is going to be in compression, is not a good plan regarding a proper reinforcement for the gear. In a hard landing scenario, the rear of the landing gear plate is under compression, but the front of it, the part attached to the firewall, is in tension, trying to pull apart. No matter what you do on the inside of the structure, that china ply plate is going to pull right out.

If the firewall were extended downward, like many other planes are designed/built, you could attach tri stock or something to the back of that to block the landing gear in place. Without that downward firewall extension, the design we're working with leaves you with a 90 degree joint that's impossible to set up leaving the front of the landing gear plate in compression (to prevent it from simply delaminating on a hard landing). That's the reason guys are glassing it or using aluminum to beef it up on the outside. FWIW, -Al

JH313

Hello,
Thank you for the replies and the help. I am still debating how I want to go. I think on ailerons I will stay with 2-56, but go to 4-40 on the elevator and rudder. As for the connection, should I use sullivan clevises or bolt-on ball joints? What about on the other side of the pushrod, I know ahicks said to avoid sodler, so should i just use the bend as the manual suggests. While I often mod planes, most of the time I leave linkages alone, so I am still learning.
Thanks again.

ahicks

My Feedback: (2)

If you mentioned what you're going to be using for power, and how you plan to fly it, I don't remember. How heavy the flight surface controls need to be depend on both? I would not use Z bends on a plane bigger than about a .60 size glow. That's me though...

VictoryRoll

My Feedback: (2)

I completely agree with @ahicks. Al has a tremendous amount of experience & knowledge and I personally follow his suggestions, recommendations and instructions. No Z-Bends, 4-40 on everything. Why would you stop putting 4-40 rods at the tail-feathers? If you're taking the time to make that change(improvement), you might as well do the whole job correctly and have a plane ready for hard maneuvers when you are ready to perform them? Ball joints on everything, if you ask me. I started using them a few years back and never looked back. They can compensate for a slight mis-alignment(s) of control horns or whatever.

One last thought. Personally, I do two things, in addition to follow the suggestions/recommendations from people like Al and Bill (@wjcalhoun) in this thread.

1). I look at Giant scale planes and what they use, and then scale it down for the size of my plane. I use their techniques, control rod types, hinges (pin hinges like Robart), control horns, etc. etc. If it's good enough for them and their $10,000+ planes, it is certainly good enough for me... but again, I scale it back to both fit and equal the job at hand.

2). Here is a website that has helped me with some "How-To's" in plane setup(s). It is for Pattern Planes and Pattern flying, which is NOT what I do, BUT... If I can set my plane up "close" to what you would do for pattern, I know I am going to have a rock-solid, straight & true, very-good to great performing plane. To me, the Revolver is a plane that would enjoy the benefits of some of these techniques & tips for pattern planes/flying.

http://www.centralhobbies.com/instructional/instrct.htm

Hope that helps some.

-VR-

P.S. One last VERY IMPORTANT ITEM: There are NO perfect methods, products, etc. in this great hobby, as in life. What YOU decide and want is what is most important, and NOT what I think, or anyone else. These are just suggestions and that is all. ..and, as you probably already know; THE most important thing is to have fun. Mistakes are part of the enjoyment... you laugh at yourself later when the hurt is over! ... and you have the money to buy that next beauty that you've had your eye on!

Have fun JH !

JH313

Ahicks, I'm using the DLE-20, which is why I am trying to learn as much as possible. Victory Roll, thanks for the advice, I will be reading the link you sent me very soon. I will use 4-40 throughout and I will use ball links on the surfaces. Would these be the ones to use: http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXCJSC&P=7.
What about on the non-threaded side where it connects to the servo, what should I use there?
Thank you again.