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Oct 17, 2019, 09:14 PM
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Wintr's Avatar
The tail wheel on mine would bounce left and right, and sometimes abruptly spring over into a hard spin. I took it apart and found two things: 1. the tube the control wire ran through wasn't glued in enough places, allowing it to bend and flex whenever side forces were applied, which accounted for the bad handling, and 2. the control arm could actually move past the full forward position, and lock it into a hard turn, staying there until something bounced it back over. Careful glue on the tube, and a small block of foam to limit the motion of the arm, tamed mine.
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Oct 18, 2019, 01:57 AM
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I have several planes with conventional landing gear (as opposed to tricycle). A Super Decathlon, Staggerwing, P-47, Stuka and probably a few more still in boxes. They all have their characteristics but with practice you should be able to get a hold of what is needed to land them and taxi in or out.

It is usually a delicate balance of rudder and elevator. Give it up elevator to keep the tail planted, but you have to ease up on that when getting up to takeoff speed and let wheel come up and keep straight with rudder. Landing is the opposite - got to control with rudder until speed reduces and tail comes down on it's own, then add elevator to keep it there and steer with wheel.

I am sure the Pandora has it's own quirks and as Wintr stated, mechanical problems that need to be overcome.
Oct 18, 2019, 09:07 PM
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Thanks for the mechanical tips Wintr. I'm definitely going to have a look inside that tail section like you mentioned. Limiting that arm sounds like a good idea - I've had mine lock up once or twice already and didn't realize what was happening at first.

SS - I will continue to try to finesse the takeoffs and landings like you've explained. Hopefully your techniques plus some mechanical mods will make a difference.

I received the 10x7 and 11x5.5 props today - will swap back to the Emax and get some additional watt meter readings ...

Oct 19, 2019, 09:33 PM
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I did some work on that tail wheel tonight to reduce slop

First on the tail wheel, I replaced that plastic screw on cap with a DuBro collar and snugged the wheel up against the bend in the axle. It has a little bit of friction now when it spins, but it doesn't jiggle around on the shaft nearly as much.

Second, I discovered a lot of slop in the steering mechanism that holds and rotates the tail axle. The metal axle inside the plastic boss had way too much wiggle room. Luckily, I found a brass tube in that assortment I ordered last month that fits the shaft almost perfectly - it's just a tad bit on the short side though. I enlarged the hole in the boss and pressed/tapped that brass tube in. Now there's very little slop here!

In order to get that steering assembly out I had to poke a hole in the fuselage so I could get a hex driver on that set screw. Hope the plane doesn't mind - now it's serviceable at least

We'll see how this does on the next flights, and how well/how long it holds up.

Next I'll work on limiting the movement back there ...
Last edited by FR4-Pilot; Oct 19, 2019 at 09:53 PM.
Oct 19, 2019, 10:13 PM
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Nice work! Now that you mention it, I needed a bit of brass tubing, for the same purpose, and also punched the small hole for the hex wrench. It's been a few years since I did all that, and didn't take photos, just got it done so I could fly.

I don't have any idea how they tighten that grub screw at the factory, but the small hole makes it easy.
Last edited by Wintr; Oct 20, 2019 at 10:57 AM.
Oct 19, 2019, 11:09 PM
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Sometimes we need to punch holes. After the stab is glued into the rear of the Durafly 1100mm Stuka, you can't get at the screw to adjust the tailwheel. I punched a hole in my stab to get at the screw.

Good work, hoping it pays off big.
Oct 21, 2019, 12:41 PM
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Thanks guys
After 4 more flights I’m liking the 850kv with 12x6x2 a little more. Less wind so she flew much better than the other day.
The steering fix held up great, but the tail wheel is sloppy again. Oh well - I’ll keep at it.
Oct 21, 2019, 01:21 PM
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Since I still don't have a Pandora I have to ask. What does it look like between the tail wheel horn and the servo that operates it. Is it a straight rod, or is there some type of servo saver to reduce the shocks to the servo? Does the tailwheel have it's own servo or is it on the rudder servo?
Oct 21, 2019, 06:51 PM
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Just a straight rod between the rear control arm and the servo.

The rudder and tail wheel have separate rods, but they're joined in the same link stop at the servo.
The unused link stop on the other arm of the tail servo is for the front nose gear, when installed.

I was thinking of 'borrowing' that other link stop and putting it in the inner hole on the other side, then moving the tail wheel push-rod to that one, to limit it's rotation angle a bit.

The rudder/steering servo is larger (17g) on the newer version of the plane. The original was a 9g servo, like the elevator, which was easily damaged from what I've read.

The tail wheel is spec'd for 2.2mm center hole/shaft. I measured the shaft and it's more like 1.98mm, so maybe I can find a tail wheel with a smaller hole.

A couple of times during yesterday's flights I noticed some pretty good vertical climbing, for at least a second or two. I suppose that's the larger prop diameter creating a wider cone of thrust ... (?)
Last edited by FR4-Pilot; Oct 21, 2019 at 07:07 PM.
Oct 21, 2019, 07:27 PM
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I suppose this guy could work:
https://www.motionrc.com/collections...ail-wheel-1-25

Or this, along with some mods, could be something to replace the existing setup:
https://www.motionrc.com/collections...for-40-90-size
I bet the tail wheel doesn't flop around too much with this design. Just hooking up the linkage needs to be worked out.

Hmmm ...
Oct 21, 2019, 10:28 PM
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That second one is for a much larger plane.

I can't say a spring linkage is really needed all that much, the tailwheel on this fairly light plane shouldn't get knocked around enough to damage the servo, never did on my Apprentice for the nose wheel, it would just break the pin on the plastic clevis, which was the weak link in the system to keep from breaking the servo.

Was really asking if there was some sort of servo saver in case that could be adjusted to keep it from being too sloppy.
Oct 22, 2019, 09:05 PM
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I really think the tail wheel simply has no authority once the plane is moving faster than a crawl. In fact, I noticed multiple times that I cannot take off in the intended direction if there's a crosswind - the plane will instantly weather vane into the wind every time regardless of steering countermeasures.

I think the tricycle gear should do better simply because most of the plane's weight will be distributed more equally among the three front wheels, with the weight of the battery, motor, and ESC directly over the nose/steering wheel. Not enough weight in the back for that wheel to do much other than slip and slide around. Doesn't really matter if it's loose and wiggles on the bent wire shaft or not.

Might as well just have a plastic skid back there - probably would behave almost exactly the same.

Maybe the soft porous foam tires are simply not 'grippy' enough and some rubber treads could help (?)
Last edited by FR4-Pilot; Oct 22, 2019 at 09:17 PM.
Oct 22, 2019, 09:16 PM
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Once the tire leaves the ground the rudder is the only thing left to turn any taildragger, tail wheel is really only useful to taxi to field, once the prop wash goes across the stabilizer the tail starts to come up. You can pin it down to some extent with up elevator, but you can't keep it down like that because you will have a premature takeoff that may end in a stall on takeoff if you don't get to full power fast.

You probably need to practice takeoff and landings with a crosswind. I don't always get them either and still practice, seems once I learn how to get it on one plane, I forget what I learned on the last plane, as they are all different!
Oct 22, 2019, 09:22 PM
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On this one it will weather vane while the tail wheel is on the ground (pavement or grass) - it simply slides sideways until it's aligned with the wind. I've watched it do it multiple times unfortunately.

It's frustrating when the runway tracks east-west, and the cross wind is from the south (or north). Slowly increasing speed causes the tail wheel to almost instantly loose grip as the plane turns into the wind and has to take off immediately perpendicular to the runway or shoot into the grass. I've noticed when the tail does in fact come up the rudder has a little bit of influence, but not enough to straighten the plane out before having to gun it and take off before crossing the edge of the runway into the grass. It just looks very reckless and out of control (probably because it is).

On the other hand, if I'm lucky enough to be able to take off directly into the wind it behaves much, much better, not veering or changing direction hardly at all.

It's still fun, and better than being at work
Last edited by FR4-Pilot; Oct 22, 2019 at 09:35 PM.
Oct 22, 2019, 10:08 PM
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I get that with my FMS Staggerwing all the time, this past weekend I have 3 flight with it, 1 good takeoff holding it straight down the runway and lifting off .... not much wind early, then one that was weathervaned a little and I took off not straight but not too bad, then the last was a weathervaned full power takeoff. The landings were about the same, the first was okay but both the gear had to be bent back to be able to retract, the second the gear did not get bent at all, but I ran into the grass bordering the concrete runway and it flipped over, then the last was still a flip, but one gear had to be straightened.

We just have to keep practicing. The guys that are pro's and competitors put a few thousand flights in each year. I have around 2500 total flights in now in 5 years, only around 1000 of them are airplane, 1200 heli and the rest small in house quads mostly. It's takes time when during an average month I get 4 fly days, a great month is 6 or 7, and last year I got 11 fly days all year before deciding to join a second field in January this year. Those 11 days were due to flood openings of the Bonne Carre spillway in 2018, in 2019 it was open for almost 6 months and we are still not really back there.


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