I am in the process of helping build a beginner style electric high wing with ailerons. RCM plans Heath Parasol. I personally would put in a .20 or .25 in it but they have gone for electric. They also want two servos in the wing. I have never in over 30 years built one that way. I am still one who builds with a standard servo in the wing center with push rods an bell cranks. My question is for servo size, they seem to think each panel will do fine with a small Hitec 81 or 84. I am not sure about pressure on each panel, I was under the impression these type of servos were better suited for foam. What is the standard for these small size servos?

For such an installatiion I prefer the Hitec HS 85 and normally reserve the 81's for throttle. I have a number of airplane that I have used the 85's on dual airlerons.

Remember the servos are going to get far less load than a single servo set up especially all that load producing extrainious linkage and bellcranks.

The loads on that small 25 sized Heath Parasol will be very small indeed. People tend to get into the habit in recent years of using far more servo power than needed and not every airplane is a firebreathing aerobat.

Here are photos of two of my twin engine ships using .25's and HS-85's on the airlerons and both have been performing well for a number of years now. One of them actually is a Seniorita flown with the .25's or without and aerotowed:

John


Hmm the servers are being cranky tonight I will have to add the pics in the morning.

Error 500 still!! Must be working on the servers again? Everything John said but I still use a lot of the 81s without problems but the gear train in the 85 is better. Since the advent of the computer radio I haven't used the single servo set up, the twin set up is just easier and fool proof. I like easy.

I will pass your advice on. I guess the bell cranks do add some restraint to the aileron setup. Mine work very smoothly with never a problem. I am still on the old ages of radio thinking. I see these setups in magazines frequently but, just thought interference would be a problem with foot long servo wires. It is something I have never done. I still use my Kraft occasionally.

Think about how long the leads are on a 40% plane that may use up to three or more servos per wing half not to mention inside the fuse. They all end up plugged into the RX. One thing I do is never use extensions, I splice and solder the lead extension wires. Single servos still work well but with the computer radios it's just easier to set up and add redundancy.

We finally seem to be able to post pictures agine and anything over a one line reply.

Anyway 1 Pitts here are a couple of photos of the only a few of my ships that I promised a few days ago, using the HS-85 as well as the HS 225 mini (Which is by far my favorite).

Also for most of my custom stuff I favor simple surface mounts as in the pictures when making a conversion far simpler to do and far more practical especially at the field than the buried ailron servo plates that everyone thinks is such a must, Nope not me.

John

I have HS-81's working fine on 20 size planes. Shouldn't be a problem .

Thanks for the pictures. The servos are easily installed. Very nice job. They are quite small at that as well. I have used nothing but standards an retract servos for the longest time I really would have been afraid to try them. Running those small servos on a twin is impressive. I would bet I could use theses smaller servos on my Pitts. One thing is for sure I will take some time to search the servo charts for my next plane. The plane I am helping with still plans on going ahead with them installed as your pics. This is a real learning experience.

You do have to watch what type and size of plane you use them in. Go onto the Servo City web site and read there charts for the servos specs to get an idea of what types of servos are on the market today. It's mind boggling. I recall when we were using those new 48 inch pound servos and thought we were in tall cotton.

A couple of years ago I kit bashed a 54" wingspan, 3 channel Ace Air Scout trainer into a semi scale piper PA-12 Cub Cruiser. I added strip ailerons and used separate HS-81 servos for each aileron. They work well. I have added ailerons to several 3 channel planes when I built them and always used separate servos as for me it was easier than creating the linkage needed for a single center servo setup. My Air Scout/Piper PA-12 is powered with a .40 2 stroke and flys faster than a stock one with the recommended .25 and still no problem with the HS-81 servos.

Another option to useing 2 servos in your wing is install both servos side by side in the center of the wing by enlargeing the servo mounting hole thats allready there on a high wing trainer type. Since most trainer planes are designed to use one single servo from this location, nothing is lost in servo torque by adding a second servo adjacent to it & this solves your extension issue. It also allows for easier trimming of the planes roll axis thru the radio instead of thru the clevis and keeps the added weight closer to the center of the fuse. This is SOP for all my trainers & opens up options like adding flapperons or spoilerons etc etc. if you want. Just another option....Gene

Well I have been giving this some thought. I realize I am behind the times in setups. Only flying biplanes an warbirds, I really did not have a need for it. I will never be flying anything larger than 60 to 65 inch wings, simply because of space. I wish now I would have tried this on the last Super Fli. The plane uses barn door type ailerons, it might have had a quicker response with a modern servo setup. If it was not so much trouble I would redo the wing. But I am in the process of helping friends with their build, an starting a new biplane. This might be the way to go. This is one reason I enjoy flying the Pitts, its just quick with response, but some planes don't respond as they should an I am wondering if this would help.

There are many factors that can cause poor aileron responce and its not all related to Servo power, things such as aileron design and planform, poor gap spacing Etc.

I once flew a full scale airplane that had true strip ailerons. It was a homebuilt that was called a Stits Flutterbug even had tricycle gear using three wheelbarrow wheels. The Ailerons were very crude and full span with only about a six inchs of chord. I was helping a buddy fly off the fifty hour restriction before he could fly to other airports from his base at Fla Bob out in Riverside Ca. The bottom line was the roll response was so poor in that airlane that it was freightening.

Also the tip design has a lot to do with roll response I am no engineer but converting a simple single servo setup with say strips to two servos will basicially half the servo loads and of course perhaps increase the response a bit. Also strip ailerons can be improved a bit by not extending them full span and having an inch or so of fixed surface out at the tip.

John

A BIG advantage to using a separate servo for each aileron is the added redundancy in case of an aileron/servo failure. On at least two occasions I had an aileron system failure, and I did not even notice the failure till after landing. On many models, the plane will fly adequetley, with only one aileron working.

I have built two super Fli,s one is quit responsive the other something is wrong. I am coming to the conclusion the servo is at fault. It is a new one, which puzzles me some what. The linkages seem ok, but I have never been a fan of the aileron type used on the plane. I counter balance just as the original. So it is a neutral feeling on the servo, but they are so far out that I think it would not be practical to use seperate servos. I will change the servo out today an see if it helps. I love to fly the plane but on the next biplane I will be using dual servos on the ailerons. I am also going to go with faster servos to boot. May not be called for but it will be a learning experience.

Not sure what a Super Fli is but I am thinking you are talking about a variation on one of the old Kraft Quick Fli's or Flea Fli but not really important anyway since you are talking about a single servo installation.

By all means go ahead and change out the servo if you suspect that is at all. Thats also a common mistake by fellows in the past and while they may have owned many airplanes most of us had very few servos and mostly we all tended to stick with the for basics that came with our systems. There was indeed a strong resistance to change out or add a servo likely because of cost in the dim past.


Things are different now with the cost of an aircrafts servo suit being a relitively smaller percentage of the total cost for each airplane than in the past and this even applies to a lot of quality or higher performance servos. So the tendency these days is to not only use dual aileron servos but most of use own hundreds of servos beyond what is permanent in each airplane and there are always choices.


Changing out the servo is or may be the easyest step now and thats fine but of course you will run into the old buggaboo of a single servo wing if you have bellcranks and pushrods which the Phil Krafts Quick Flis did use and that is the royal pain it was to simply remove or reinstall a servo with those double ended pushrods and ball joints etc.

I have not found any old type with a single servo that was a problem to convert to dual servos regardless as to how far out in the wing the servo is so not sure what you mean there, but its all good

John

Another advantage of the two servo in the wing setup is the added space in the fuselage radio comparment. Sometimes it gets crowded in a small fuselage with the servo in the center of the wing protruding into the servo/reeceiver/battery area and the linkage going back to the torque rods. That is all gone making a much cleaner area.

The Super Fli is the only full size aircraft Phil Kraft designed an built. I am not sure where she is today but she was built using some of the ideas he learned from models. It is a clean flyer, no real bad habits, easily fly with any pattern plane an with the proper motor can compete with the Extra 300, etc. An Internet search will find you a few pics of Kraft an the model an the full size one. Most planes in pattern flying of the day looked odd the Super Fli looks like a real craft. I was disadvantage in some events when successfully raising or lowering retracts was given points. I've never been good enough to fly expert class. To old now for that now.
I changed out the servo an fixed my problems. The servo has a strange problem that I believe is caused by vibration or heat after a little use. I watched the ailerons continually during flight an when the troubles started I brought it down quickly. On the ground it worked perfectly. Puzzled someone said to keep working with the servo an in about a minute of use the servo acted up an was somewhat warm, an was jerky with a slower response. Sufficient to say the servo was at fault. Few ever fail unless there's a crash of some sort but you get a dud once in a while.
I want to try this dual servo setup so much I am thinking of replacing the servos in a scratch built Schweizer 1-30 motor glider. She has a .20 for power that I want to change out to electric an this might be a good place to try to lighten the loading with electric an new servos in a dual setup. I'll let you guys know what I decide in a few days.

Well that certainly explains the Mystery about the referance to a Super Fli.

The one thirty a very cool project. If I an not mistaken it was intended a tug with an o-200 or something of that sort. Was it a one off project or did Sweitzer or perhaps hughs build a few more?


I did pay my dues in full scale with TG-3's, 1-19's, 2-22's, 1-26's and 2-32's among others and spent time on both ends of the towline. Now how about forgetting the electric thing in your 1/30 and change out the .20 for an OS .25 or 35AX move the tow release from the tail to to the fuse spine just behind the canopy and go for some aero tow. That combo should prove excellent with most any two meter type. One of my favored RC activitys when I can find fellows willing to learn either end of the towline.

John