Author Topic: New Plane (Read 3009 times)

Motorman · « **on:** July 12, 2016, 07:26:59 PM »

The old plane flew so good I tried to build something better. The new plane feels different and is hard to control like it has a mind of it's own. From the flights I've taken so far I can tell it's a better airplane but I can't control it as good. The main thing is it needs more control input, I have to crank on the handle more. It feels sluggish and dull with my regular input then when I pull it harder the action happens quickly and it goes where ever. I built it too light (or my battery is too heavy), I had to add allot of weight to the tail to get it to balance where it said on the plans. I've been through the Walker trim sheet and it's basically ok except I don't feel connected to it like I do the old plane. Could it be flap ratio, do you think it's still nose heavy?

ThunderGazer 40 (575 sq. in.)
flap 1:1 ratio
4" Morris guts
HP Handle 3-3/4"
65' handle to spinner
45 ounces
5.3 lap

MM

Tim Wescott · « **Reply #1 on:** July 12, 2016, 07:30:49 PM »

Move the lines out on the handle? "Mind of its own" sounds like the CG is too far back, if anything. Lighter planes usually need less flap than heavier ones, but I don't know what the 'right' ratio is for a Thundergazer.

Oh -- test the control system to make sure it's as smooth as can be with no stiffness or hitches or glitches. If you have a buddy, test it under tension. That would account for the "slow control then has a mind of its own" part.

Mike Griffin · « **Reply #2 on:** July 12, 2016, 07:52:10 PM »

Did you build per the plans or did you make any changes?

Mike

Motorman · « **Reply #3 on:** July 12, 2016, 10:17:42 PM »

The only changes were to the fuselage. I left off the turtle deck and went with a bubble canopy and there's no engine cowl hanging down on the nose since it's electric and the overall smaller size (92%). The wing, tail and moments are all the same. The controls are free under load.

It flys nice and stable with good line tension until I have to over control it to get it to snap a corner.

I'm going to try less flap which should make the handle faster right?

Brent Williams · « **Reply #4 on:** July 12, 2016, 10:27:59 PM »

Pictures of this plane? Sounds cool.

Mark Scarborough · « **Reply #5 on:** July 12, 2016, 10:30:08 PM »

Quote from: Motorman on July 12, 2016, 10:17:42 PM

The only changes were to the fuselage. I left off the turtle deck and went with a bubble canopy and there's no engine cowl hanging down on the nose since it's electric and the overall smaller size (92%). The wing, tail and moments are all the same. The controls are free under load.

It flys nice and stable with good line tension until I have to over control it to get it to snap a corner.

I'm going to try less flap which should make the handle faster right?

what about some numbers, like ratio of bellcrank arm to flap arm, elevator arm,
what is your flap to elevator ratio now
Electric airplanes need the CG a fair amount farther forward than glow
is everything absolutly square, and straight
tip weight, actual measured cg location?
it helps a lot to have as much info as possible when trying to solve problems on line

Randy Cuberly · « **Reply #6 on:** July 13, 2016, 01:27:53 AM »

Quote from: Motorman on July 12, 2016, 07:26:59 PM

The old plane flew so good I tried to build something better. The new plane feels different and is hard to control like it has a mind of it's own. From the flights I've taken so far I can tell it's a better airplane but I can't control it as good. The main thing is it needs more control input, I have to crank on the handle more. It feels sluggish and dull with my regular input then when I pull it harder the action happens quickly and it goes where ever. I built it too light (or my battery is too heavy), I had to add allot of weight to the tail to get it to balance where it said on the plans. I've been through the Walker trim sheet and it's basically ok except I don't feel connected to it like I do the old plane. Could it be flap ratio, do you think it's still nose heavy?

ThunderGazer 40 (575 sq. in.)
flap 1:1 ratio
4" Morris guts
HP Handle 3-3/4"
65' handle to spinner
45 ounces
5.3 lap

MM

The Thundergazer plans (if they are plans for the full size Thundergazer) would show a CG for the IC version of the airplane and it would likely be, as most IC airplanes are, shown for the location with no fuel in the tank. It would be significantly farther forward with fuel in the tank ready to fly. The electric version with the battery in place would therefore require the CG significantly farther forward to duplicate the actual flight CG of the IC version.
Stiffness of the flaps and elevators and controls could also be a factor. Have they been tested under load?

Randy Cuberly

Steve Helmick · « **Reply #7 on:** July 13, 2016, 03:12:34 PM »

For a 575 sq.in. plane and only 45 oz RTF weight, the lines seem pretty long. If there is good line tension anyway, then perhaps the LO's are too far aft. CG is too far aft, for sure, if it is in the correct place for IC. Different deal, since there is no CG shift during flight. Will likely need to move the wheels forward, too.

Steve

Motorman · « **Reply #8 on:** July 13, 2016, 03:15:21 PM »

Steve Helmick · « **Reply #9 on:** July 13, 2016, 03:28:06 PM »

Why are you using the LH rotation propeller? Nobody does that anymore here, unless they already have a plane trimmed for a LH prop and don't want to re-trim for a RH propeller. Just sayin'....

Steve

Mark Scarborough · « **Reply #10 on:** July 13, 2016, 07:00:30 PM »

I think in looking at it, you may be fighting the prop, how big is your prop? it is a known factor that the bigger the prop, the slower the cornering.
perhaps a different prop would be one thought, something smaller. less rotational mass = better turn
thats a fairly small airplane too just for the record so the prop will make a marked difference

Mark Scarborough · « **Reply #11 on:** July 13, 2016, 07:03:14 PM »

I would also really focus on the controls. I had one airplane that was fine until you put a load on the controls and then it bound up, the bellcrank was rocking and binding

Motorman · « **Reply #12 on:** July 13, 2016, 07:43:34 PM »

I switch lines, handle and prop with the other plane, the other plane flies great. Controls are free, just did a pull test with the wifey. I'm going to check lead out travel vs elevator deflection and compare to the old plane. Maybe it just needs to be in the range I'm use to.

MM

Motorman · « **Reply #13 on:** July 13, 2016, 07:50:26 PM »

Quote from: Steve Helmick on July 13, 2016, 03:28:06 PM

Why are you using the LH rotation propeller? Nobody does that anymore here, unless they already have a plane trimmed for a LH prop and don't want to re-trim for a RH propeller. Just sayin'.... Steve

My Tanager likes pusher props so that's what I made. It worked better than any APC I ever tried. I made a second one and left the overhang on it for more diameter and it worked even better. So naturally I put it on the new plane. I've got a lighter CF version in the mold right now.

MM

Steve Helmick · « **Reply #14 on:** July 15, 2016, 01:19:58 PM »

The deal with LH props (for CCW flying) is that they are reported to mess up the 2nd or 3rd corner of the Hourglass. But that's from the electric guys that have tried both, Paul, Howard, Chris and Mike. Alan flies CW, so he's always used a LH prop on electrics. If he wanted to experience the same problem at the top of the hourglass, he could use a RH prop for a thrill.

I've only flown IC, so I'm happily stuck with RH props. But I still keep my ears open, at least until they start whining about their battery failing after only 50 charges.

Steve

FLOYD CARTER · « **Reply #15 on:** July 15, 2016, 01:24:47 PM »

But wait! People are saying that sluggish response is CG too far aft. I think they mean the CG is too far forward. It is nose-heavy. Weight and lap times seem about right. A 4" bellcrank also means a larger handle line spacing is needed.

Floyd

Motorman · « **Reply #16 on:** July 15, 2016, 05:50:37 PM »

I got it working. I measured the lead out travel at 25 degrees elevator on the Tanager and got 1-5/16". Then I got 1-9/16" on the Tundergrazer 1/4" difference. I shortened the elevator control horn until it was the same travel as the Tanager. Wow what a difference, very responsive and controllable. I took one of the tail weights off and it smoothed it out just right.

The wind was very turbulent and gusty so I didn't get to do the pattern but, I'm looking forward to it tomorrow.

Steve Helmick · « **Reply #17 on:** July 15, 2016, 10:05:28 PM »

So, basically, your handle spacing was too narrow and your CG too far aft. It's about control ratios, not specifically "leadout travel", tho of course that's part of it. Hope your weather improves (ours is also sucky) and you can get some patterns in!

Steve

Motorman · « **Reply #18 on:** July 16, 2016, 06:57:18 AM »

How do you compare control ratios of two planes? I guess most adjust the handles line spacing. All my handles are fixed at 3-3/4" where I like it but, I'll be making a 4" for this plane so I can get some of my flap ratio back.

On the next one I'll put the bellcrank pushrod lower on the flap horn until I get the lead out travel I like with 25 degree elevator Now that I know the number.

The old plane had Brodak system and the new one has Tom Morris. The Morris system was a good bit slower but lucky for me was adjustable.

Now I'm curious about how sensitive people like their controls.

Anyway guys, thanks for all the help and suggestions.

MM

Alan Resinger · « **Reply #19 on:** July 16, 2016, 08:37:24 AM »

Steve,
Even though I fly CW, I have always used RH props. When I started making LH electric props a few years back for all the CCW flyers I thought I'd try one to see what those guys had been going through for years with RH props. The experiment lasted about 3 take offs with the plane feeling like it was going to chase me out of the circle. No matter what rotation you use, either flying CW or CCW there are trade-offs. One will help in some places while the other will help in others. You just have to trim your plane to its best with the prop and rotation you prefer. Paul's early electric efforts flew just fine with the LH prop. He just found that he had less trimming problems to overcome by going back to RH rotation.
If you really want to get the lowdown on the difference in trim, take your model off and flip it upside down and then do the pattern starting from inverted. I've done it and be prepared for some eye opening results. You'll fine places in the pattern that were normally easy to fly with good line tension and solid corners, to suddenly requiring a few steps back to regain line tension. The first time you try it, I suggest flying somewhat large, not too tight a corner and keep the bottoms at 10-12 feet.
When Paul was first starting to fly a tuned pipe plane he built a small test ship that I flew. Picked the handle up upside down, took off like I was inverted, flipped the plane inverted and flew the pattern. Was an interesting experiment.
Alan

Steve Helmick · « **Reply #20 on:** July 16, 2016, 04:17:48 PM »

Quote from: Alan Resinger on July 16, 2016, 08:37:24 AM

Steve,
Even though I fly CW, I have always used RH props. When I started making LH electric props a few years back for all the CCW flyers I thought I'd try one to see what those guys had been going through for years with RH props. The experiment lasted about 3 take offs with the plane feeling like it was going to chase me out of the circle. No matter what rotation you use, either flying CW or CCW there are trade-offs. One will help in some places while the other will help in others. You just have to trim your plane to its best with the prop and rotation you prefer. Paul's early electric efforts flew just fine with the LH prop. He just found that he had less trimming problems to overcome by going back to RH rotation.
If you really want to get the lowdown on the difference in trim, take your model off and flip it upside down and then do the pattern starting from inverted. I've done it and be prepared for some eye opening results. You'll fine places in the pattern that were normally easy to fly with good line tension and solid corners, to suddenly requiring a few steps back to regain line tension. The first time you try it, I suggest flying somewhat large, not too tight a corner and keep the bottoms at 10-12 feet.
When Paul was first starting to fly a tuned pipe plane he built a small test ship that I flew. Picked the handle up upside down, took off like I was inverted, flipped the plane inverted and flew the pattern. Was an interesting experiment.
Alan

Hahahahaha! No! I'm looking forward to flying my first flight this year. It will not be very experimental. Interesting, maybe?

I figured that you had actually tried a RH prop on your 'lectric, but knew you didn't normally do it.

Was that test ship of PW's the flying wing devise with the .32? I've seen that fly at Fun-Fly(s), Paul laying on his back in the grass and doing the whole pattern. Must fly ok...

Steve