Balancing tailerons?
04-23-2005 | 02:36 PM
#1
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Balancing tailerons?
I have attempted here to calculate the MAC and placed the pivot point at 25%. the 'actuator' is at the rear and the fuse and will link to the servo which will be inside. I placed some weights, as you can hopefully see, to balance the taileron, which is quite tail heavy. The question here is whether this the way to set up this surface to provide the best operation? If it matters, the surface will built up (lightening holes in the ply), sheeted, and glassed. It will be more or less symmetrical airfoil. Any thoughts? Bill S.
04-23-2005 | 03:15 PM
#2
Senior Member
RE: Balancing tailerons?
Balance it just a bit tail heavy, to provide some inertial damping.
The hinge point a percentage or two ahead of the 25% point provides aerodynamic damping.
The hinge point a percentage or two ahead of the 25% point provides aerodynamic damping.
04-23-2005 | 06:35 PM
#3
My Feedback: (5)
RE: Balancing tailerons?
ORIGINAL: wsmalley
I have attempted here to calculate the MAC and placed the pivot point at 25%. the 'actuator' is at the rear and the fuse and will link to the servo which will be inside. I placed some weights, as you can hopefully see, to balance the taileron, which is quite tail heavy. The question here is whether this the way to set up this surface to provide the best operation? If it matters, the surface will built up (lightening holes in the ply), sheeted, and glassed. It will be more or less symmetrical airfoil. Any thoughts? Bill S.
I have attempted here to calculate the MAC and placed the pivot point at 25%. the 'actuator' is at the rear and the fuse and will link to the servo which will be inside. I placed some weights, as you can hopefully see, to balance the taileron, which is quite tail heavy. The question here is whether this the way to set up this surface to provide the best operation? If it matters, the surface will built up (lightening holes in the ply), sheeted, and glassed. It will be more or less symmetrical airfoil. Any thoughts? Bill S.
Looks like you're building a Flanker. Is that your own design? What's the power system going to be?
Dan
04-23-2005 | 07:03 PM
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RE: Balancing tailerons?
Yep, it's a Flanker, 9' OAL. Bertelli plans, much modified (for example, he drew fixed stabs and elevators). Being on the poor side, I've got 2 'low mileage' JPX 260P's, trying to shoehorn everything into the fuse is a challenge. The propane tanks just do fit into the intakes. I am looking at the new Jet Joe turbines with interest. Scratch building the gear due to the wierd geometry of the mains. I've got a Japanese made video of the Su 27 that's got some of the best photography I've ever seen (called Ram-K)which allows one to see all the control surface movements. Getting ready to cut in the LE flaps, as soon as I work up the courage-fearing making a mistake! The tailerons will use 1/4" shafts in 1/4 X 5/8 bearings mounted in AC ply bearing blocks. Probably two servos each side.
04-27-2005 | 09:01 PM
#5
My Feedback: (5)
RE: Balancing tailerons?
ORIGINAL: wsmalley
Yep, it's a Flanker, 9' OAL. Bertelli plans, much modified (for example, he drew fixed stabs and elevators). Being on the poor side, I've got 2 'low mileage' JPX 260P's, trying to shoehorn everything into the fuse is a challenge. The propane tanks just do fit into the intakes. I am looking at the new Jet Joe turbines with interest. Scratch building the gear due to the wierd geometry of the mains. I've got a Japanese made video of the Su 27 that's got some of the best photography I've ever seen (called Ram-K)which allows one to see all the control surface movements. Getting ready to cut in the LE flaps, as soon as I work up the courage-fearing making a mistake! The tailerons will use 1/4" shafts in 1/4 X 5/8 bearings mounted in AC ply bearing blocks. Probably two servos each side.
Yep, it's a Flanker, 9' OAL. Bertelli plans, much modified (for example, he drew fixed stabs and elevators). Being on the poor side, I've got 2 'low mileage' JPX 260P's, trying to shoehorn everything into the fuse is a challenge. The propane tanks just do fit into the intakes. I am looking at the new Jet Joe turbines with interest. Scratch building the gear due to the wierd geometry of the mains. I've got a Japanese made video of the Su 27 that's got some of the best photography I've ever seen (called Ram-K)which allows one to see all the control surface movements. Getting ready to cut in the LE flaps, as soon as I work up the courage-fearing making a mistake! The tailerons will use 1/4" shafts in 1/4 X 5/8 bearings mounted in AC ply bearing blocks. Probably two servos each side.
I make and sell a little twin EDF wood Flanker kit, so I know what you mean about the limited amount of space inside. I'd imagine the GRP models have a bit more room thanks to the reduction in internal structures. Even so, there's not that much room inside. The Flanker is actually a pretty trim design with no excess bumps or bulges.
I'm keeping my eye on JJ, too. I ordered the Flankers CD from Russia and it has video on it that sounds similar. It even shows the inlet screens moving up and down.
When you say 1/4"shafts, I assume you mean 1/4" steel shafts, correct? I wouldn't trust a model of that size to a flimsy 1/4" aluminum shaft.
If you'd like to check out my kits, go to: http://SavageLight.com
You might think about posting a thread on the Jet forum. I'm sure everyone would like to follow your progress like they have with Harald's Flanker.
Dan
04-27-2005 | 09:42 PM
#6
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RE: Balancing tailerons?
With regard to the shafts, I may wind up with steel, and may even go to larger ID bearings. I'm starting with 3 telescoping thicknesses of brass tube. The idea there was to solder a perpindicular piece on the end like a 'T' so there is no movement. I could, of course, weld steel but it would be more difficult to have bolts/screws. Right now I'm wrestling with how, or whether, to gang 2 servos together for each taileron-and getting the rudder servo(s) in there too. I like things to 'bolt' together rather than rely on glue for high stress parts. I have considered using all my electronic gear for the fun of it to essentially build a UAV. Have color cam Tx/Rx, a BTA-06 auto pilot and the PDC10 device which couples to a a gps into which you program waypoints. Of course with a 6 minute fuel supply you ain't goin' too far! I like the electrics and certainly the EDF's have come a long way recently. I've seen your site before-very nice planes. At the same time, I am 'finishing up' a Skyray and 4 prop jobs- 2 seaplanes, a Cub and a Storch. Man's got to have his priorities in order!
05-01-2005 | 01:28 AM
#7
My Feedback: (5)
RE: Balancing tailerons?
ORIGINAL: wsmalley
With regard to the shafts, I may wind up with steel, and may even go to larger ID bearings. I'm starting with 3 telescoping thicknesses of brass tube. The idea there was to solder a perpindicular piece on the end like a 'T' so there is no movement. I could, of course, weld steel but it would be more difficult to have bolts/screws. Right now I'm wrestling with how, or whether, to gang 2 servos together for each taileron-and getting the rudder servo(s) in there too. I like things to 'bolt' together rather than rely on glue for high stress parts. I have considered using all my electronic gear for the fun of it to essentially build a UAV. Have color cam Tx/Rx, a BTA-06 auto pilot and the PDC10 device which couples to a a gps into which you program waypoints. Of course with a 6 minute fuel supply you ain't goin' too far! I like the electrics and certainly the EDF's have come a long way recently. I've seen your site before-very nice planes. At the same time, I am 'finishing up' a Skyray and 4 prop jobs- 2 seaplanes, a Cub and a Storch. Man's got to have his priorities in order!
With regard to the shafts, I may wind up with steel, and may even go to larger ID bearings. I'm starting with 3 telescoping thicknesses of brass tube. The idea there was to solder a perpindicular piece on the end like a 'T' so there is no movement. I could, of course, weld steel but it would be more difficult to have bolts/screws. Right now I'm wrestling with how, or whether, to gang 2 servos together for each taileron-and getting the rudder servo(s) in there too. I like things to 'bolt' together rather than rely on glue for high stress parts. I have considered using all my electronic gear for the fun of it to essentially build a UAV. Have color cam Tx/Rx, a BTA-06 auto pilot and the PDC10 device which couples to a a gps into which you program waypoints. Of course with a 6 minute fuel supply you ain't goin' too far! I like the electrics and certainly the EDF's have come a long way recently. I've seen your site before-very nice planes. At the same time, I am 'finishing up' a Skyray and 4 prop jobs- 2 seaplanes, a Cub and a Storch. Man's got to have his priorities in order!
I'm not sure where on the stab's MAC the pivot point lies, but if it's anywhere from 20-25%, then I'm not sure you'll need 2 servos per elevator side. The aerodynamic balance is pretty effective.
I had a chance to fly a prospective USMC UAV basic trainer (zagi w/color cam) and it was pretty cool.
Thanks. I'm currently building one of the Flanker variants, the Su-27IB Platypus using a conversion kit I designed for our Su-27 kit and I just converted my old glow-powered Pilot Decathlon .40 to electric power, so I know what you mean by priorities.
Dan
05-01-2005 | 11:03 AM
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RE: Balancing tailerons?
I am hoping you are correct about the servo. This was a suggestion by someone else based on how he set up his '27'-though I don't know the facts how he did it. Some have put the actuator arm directly on the pivot tube. I have put the arm-or actuator- on the rear (like the full scale) of the taileron. This where I calculated the 'mass balance' point to be. The effort to move the surface that way is extremely light. I plan to 'imbed' the 'T' in the ply(1/8th light), make ribs, top and bottom, drill some lightening holes, and skin them with 1/64th ply. That stuff soaks the CA well and is tough as nails. The LG has taken me so long to design/buildthat it has slowed me down. I am building some 'scale' working disc brakes for it and have the rotor built and the caliper about done. The piston turned out to be easier than I thought. I use a short piece of 3/8th alum rod turned to hold an 'O' ring. So far it takes very little air pressure to make them work. The 'pads' have yet to be worked out. I am thinking of using some RC car pads to try, thus far I've tried sandpaper glued to the press plate to test the theory.
05-03-2005 | 05:24 PM
#9
My Feedback: (5)
RE: Balancing tailerons?
ORIGINAL: wsmalley
I am hoping you are correct about the servo. This was a suggestion by someone else based on how he set up his '27'-though I don't know the facts how he did it. Some have put the actuator arm directly on the pivot tube. I have put the arm-or actuator- on the rear (like the full scale) of the taileron. This where I calculated the 'mass balance' point to be. The effort to move the surface that way is extremely light. I plan to 'imbed' the 'T' in the ply(1/8th light), make ribs, top and bottom, drill some lightening holes, and skin them with 1/64th ply. That stuff soaks the CA well and is tough as nails. The LG has taken me so long to design/buildthat it has slowed me down. I am building some 'scale' working disc brakes for it and have the rotor built and the caliper about done. The piston turned out to be easier than I thought. I use a short piece of 3/8th alum rod turned to hold an 'O' ring. So far it takes very little air pressure to make them work. The 'pads' have yet to be worked out. I am thinking of using some RC car pads to try, thus far I've tried sandpaper glued to the press plate to test the theory.
I am hoping you are correct about the servo. This was a suggestion by someone else based on how he set up his '27'-though I don't know the facts how he did it. Some have put the actuator arm directly on the pivot tube. I have put the arm-or actuator- on the rear (like the full scale) of the taileron. This where I calculated the 'mass balance' point to be. The effort to move the surface that way is extremely light. I plan to 'imbed' the 'T' in the ply(1/8th light), make ribs, top and bottom, drill some lightening holes, and skin them with 1/64th ply. That stuff soaks the CA well and is tough as nails. The LG has taken me so long to design/buildthat it has slowed me down. I am building some 'scale' working disc brakes for it and have the rotor built and the caliper about done. The piston turned out to be easier than I thought. I use a short piece of 3/8th alum rod turned to hold an 'O' ring. So far it takes very little air pressure to make them work. The 'pads' have yet to be worked out. I am thinking of using some RC car pads to try, thus far I've tried sandpaper glued to the press plate to test the theory.
Looking at the pic you posted, it looks like the control horn is located way aft of the pivot. If this is the case, then the only problem I can see is this arrangement will limit the amount of throw you'll get from the system and the tailplane will need a lot of throw for elevator action.
Wow! Home-made brakes, huh? Instead of sandpaper, try leather. I think that's what the early car builders used on their brakes and it won't wear out your rotor as quickly as sandpaper.
Dan
05-03-2005 | 08:33 PM
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RE: Balancing tailerons?
I have noticed the amount of throw does seem to be pretty extensive-working it strictly by hand at this point. What kind of throw do you think will be required? I will next work on the 'tunnel' thingy under the rudder which houses the actuator, to see if the movement is what I think it should be- that is, if it will all fit and work properly. That's the full scale way which uses a hydraulic cylinder. The "Ram-K" DVD I mentioned shows the preflight movement to be about 40-45 degrees movement up and down, but very small movements to actually rotate or roll the plane. Leather huh, hadn't thought of that. The sandpaper was only a test, 'til I came up with something better.
05-03-2005 | 10:15 PM
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From: Deland,
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RE: Balancing tailerons?
Remember, low aspect ratio swept surfaces like this have shallow lift curves, that is, the lift per angle of attack is relatively low. So, you are going to need a good bit of throw, and they will be relatively easy to fly smoothly. Plus, you need to have enough throw on the surface to go to full elevator and still more to deflect for aileron effect.
05-04-2005 | 04:09 AM
#12
My Feedback: (5)
RE: Balancing tailerons?
ORIGINAL: wsmalley
I have noticed the amount of throw does seem to be pretty extensive-working it strictly by hand at this point. What kind of throw do you think will be required? I will next work on the 'tunnel' thingy under the rudder which houses the actuator, to see if the movement is what I think it should be- that is, if it will all fit and work properly. That's the full scale way which uses a hydraulic cylinder. The "Ram-K" DVD I mentioned shows the preflight movement to be about 40-45 degrees movement up and down, but very small movements to actually rotate or roll the plane. Leather huh, hadn't thought of that. The sandpaper was only a test, 'til I came up with something better.
I have noticed the amount of throw does seem to be pretty extensive-working it strictly by hand at this point. What kind of throw do you think will be required? I will next work on the 'tunnel' thingy under the rudder which houses the actuator, to see if the movement is what I think it should be- that is, if it will all fit and work properly. That's the full scale way which uses a hydraulic cylinder. The "Ram-K" DVD I mentioned shows the preflight movement to be about 40-45 degrees movement up and down, but very small movements to actually rotate or roll the plane. Leather huh, hadn't thought of that. The sandpaper was only a test, 'til I came up with something better.
This is with the CG at 25% MAC and the model is very controllable and comfortable to fly without being overly sensitive. Other than having a great deal more inertia to deal with from a much larger model, I wouldn't imagine you'd need more control throw than this. At the very least, this gives you a good starting point.
Reflecting on it a little more, leather has a couple of problems. First, it would probably get 'grabby' if it got wet. It also swells when it gets wet. (Eww...) Maybe some nomex paper would work better. I'm sure you'll find something suitable.
Dan
05-05-2005 | 01:30 PM
#13
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RE: Balancing tailerons?
Thanks for the info/ comments. I hadn't thought about the lift curve so as I progress, I'll watch the throw. I watched the Su video of your plane, Dan, and it looks like it flys quite well. I'll try and upload a couple of pics. Right now I have a BB 48 oz servo and 4-40 rod, but just for a mockup. The surface moves quite easily but too much 'give'. I'll need aluminum arm and probably 3/16 th to 1/4" rods
05-06-2005 | 03:15 AM
#15
My Feedback: (5)
RE: Balancing tailerons?
ORIGINAL: wsmalley
Thanks for the info/ comments. I hadn't thought about the lift curve so as I progress, I'll watch the throw. I watched the Su video of your plane, Dan, and it looks like it flys quite well. I'll try and upload a couple of pics. Right now I have a BB 48 oz servo and 4-40 rod, but just for a mockup. The surface moves quite easily but too much 'give'. I'll need aluminum arm and probably 3/16 th to 1/4" rods
Thanks for the info/ comments. I hadn't thought about the lift curve so as I progress, I'll watch the throw. I watched the Su video of your plane, Dan, and it looks like it flys quite well. I'll try and upload a couple of pics. Right now I have a BB 48 oz servo and 4-40 rod, but just for a mockup. The surface moves quite easily but too much 'give'. I'll need aluminum arm and probably 3/16 th to 1/4" rods
Yeah, you don't want to have the elevon pushrods bending under load. Daren almost lost his prototype model that way.
Your model is looking good so far. Thanks for the pics.
Dan
