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  • May 10, 2021, 01:40:22 PM

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Author Topic: Loose Lines Sink Ships  (Read 490 times)

Online Dave Moritz

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Loose Lines Sink Ships
« on: April 28, 2021, 08:25:00 AM »
I've got a basic, 101-type question. Am having to back up quite a bit on takeoff for a couple of my fun, "experimental" model projects. Engine offset is likely called for. What else could be at work here, or is this the only solution?

Dave Mo...

Offline Dan McEntee

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Re: Loose Lines Sink Ships
« Reply #1 on: April 28, 2021, 09:49:07 AM »
I've got a basic, 101-type question. Am having to back up quite a bit on takeoff for a couple of my fun, "experimental" model projects. Engine offset is likely called for. What else could be at work here, or is this the only solution?

Dave Mo...

    While on the ground, your model can suffer or benefit from wheel alignment just like your car. I take my models to the paved pad at Buder Park or the street and just roll them across the ground to see how they track. If they roll straight, you should be good to go. If one wheel axle is pointed into the circle it make influence how the model tracks. As Ty mentions, the tail wheel is what steers a tail dragger. On tricycle gear it's the nose wheel. As you fly the model a lot and put some time on it, observe how the wheels are wearing. The newer, foam type light wheels will show up miss alignment very well. Make sure the wheels are even from front to back. A simple toe in adjustment can cure a lot of ills, just like on your car. Make it just enough that you can see it. It's all part of trimming out a model!
  Type at you later,
    Dan McEntee
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Offline Dan McEntee

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Re: Loose Lines Sink Ships
« Reply #2 on: April 28, 2021, 10:08:40 AM »
   I forgot to add one other thing, and that is how the model is launched can affect this also. Not everyone is the same in this aspect. Sometimes a person can let the model go "wrong" and it will do crazy things. Sometimes a slight nose out stance at release is all that is needed. Stooges can cause problems also. You just have to look at everything while you are trouble shooting the problem.
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   Dan McEntee
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Offline Jim Svitko

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Re: Loose Lines Sink Ships
« Reply #3 on: April 28, 2021, 01:25:12 PM »
Don't forget P-factor.

Online john e. holliday

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Re: Loose Lines Sink Ships
« Reply #4 on: April 28, 2021, 01:38:15 PM »
I was taught to be on your toes when taking of.  But flying out of grass if a tall weed snags a line you just hope for the best. D>K
John E. "DOC" Holliday
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Online Dave Moritz

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Re: Loose Lines Sink Ships
« Reply #5 on: April 29, 2021, 09:07:28 AM »
Gents:

Thanks for the comments, good ones all.

Yup, John, the weed factor adds an element of thrill to the endeavor. Ah the good ol' P-factor, Jim. What more can to be said? And Ty, here I thought that whipping it only had something to do with early eighties rock band members who wore collapsible flower pots on their heads.

Dan, I'll take your suggestions to heart as I launch by (mechanical) stooge. Accordingly will have to be more mindful of angles and dangles.

All the best!

Dave Mo...

Offline Dan McEntee

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Re: Loose Lines Sink Ships
« Reply #6 on: April 29, 2021, 09:34:31 AM »
Gents:

Thanks for the comments, good ones all.

Yup, John, the weed factor adds an element of thrill to the endeavor. Ah the good ol' P-factor, Jim. What more can to be said? And Ty, here I thought that whipping it only had something to do with early eighties rock band members who wore collapsible flower pots on their heads.

Dan, I'll take your suggestions to heart as I launch by (mechanical) stooge. Accordingly will have to be more mindful of angles and dangles.

All the best!

Dave Mo...

     If you can, mark out your take off space with some cheap spray paint. Set up your stooge with a model in it and lines hooked up. Go out to the handle  and see how it looks to you from there. Imagine the line sweep as if the model is in flight. If you are right handed, move to the right until you get to that point and mark that spot. Make sure your stooge can't shift when you pull the line. Take off the same way each time and be ready to step back a bit if you need to. If on grass, hold your handle hand up higher than normal. If on a paved circle with grass in the middle, position the stooge/model as far out as practical, so you have a better angle of the lines extending from the wing tip to your handle, and will clear the grass better. Have fun!!
    Type at you later,
     Dan McEntee
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Offline dale gleason

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Re: Loose Lines Sink Ships
« Reply #7 on: April 29, 2021, 11:09:25 AM »
My stunt planes are built such that the main wheels point into the circle a few degrees and I insure the launcher has the plane's nose outward a few degrees at launch. The plane is released just a little to the judges' right.(10-15 ft.)

This is really good if the wind is blowing strong.

Although the nose is out, the wheels track tangent to the circle. The nose out keeps the lines tight, especially if a gust tries to blow the tail outward.

No handle movement is required...the plane begins the TO roll with a slight downwind component so neutral elev and flap tends to keep the nose from pitching down (avoids burning a prop tip) . As the TO roll continues, the slight tailwind becomes a headwind, tail starts to come up, a teeny amount of down might be needed to keep the plane rolling, as the plane approaches flying speed relaxing that teeny bit of down handle allows the plane to leave the runway in a SLOW steady climb (vs the immediate leap into the air so often seen).

Al Rabe has left us, but, he left lots of things to remember and this is one tip he explained to me when I expressed concern his landing gear was pointed in...

dg



Online Motorman

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Re: Loose Lines Sink Ships
« Reply #8 on: May 01, 2021, 10:59:54 AM »
If you pull on the line the inner wheel can lock and point the nose in especially if there's no inner washer on a wire gear strut. Did you check the rudder alignment? Does it nose in or does the outboard wing lift? Are you taking off into the wind?

If the wing comes up you could have a warp or just a big heavy prop and light tip weight.

 As soon as the model is released it should pretty much instantly go to a nose out condition because the tether point is set back to compensate for aero drag and there is none at take off.

Motorman 8)
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Online Ted Fancher

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Re: Loose Lines Sink Ships
« Reply #9 on: May 05, 2021, 05:15:12 PM »
First off I've no serious problem with  the previous comments relative to wheel toe in, etc.  although I've not utilized such myself.  An interesting thought I'd not considered previously.  To which I'd only add that the all three wheels should turn freely although I do purposely always apply a tiny bit of  'squeeze" to the outboard main gear wheel retainer; just enough squeeze  than the outboard will have a "tiny" bit of drag when "spinning" it manually.  This is a pretty sure fire precaution against "chasing the pilot surprises" on release.

I do not, however, purposely misalign the wheels to account for yaw.  I "ground trim" my ships to roll straight ahead with that small exception of a little extra tension on the outboard wheel retainer about which more later.

(What follows is predicated on a counter clockwise upright flight ship)

Number 1 comment would be that it is the pilot's responsibility to insure his position relative to the aircraft is appropriate for the way the airplane is "trimmed"  to track on the takeoff roll.  This is particularly important if you utilize a variety of launchers.  Don't attempt to communicate with the launcher by yelling, waving an arm or pointing a finger which requires him to interpret your intent.  If the ship is nosed in too much  the pilot should move to his right and vice versa.   The pilot's responsibility for proper placement is even more imperative when launching in any significant wind.  Only he/she knows what he/she is anticipating from his/her ship due to cross/head/tail winds, etc!!  It is a good idea if using an unfamiliar launcher during adverse air conditions to brief him/her that you will be doing any desired adjustments at the handle and that he/she shouldn't take any unilateral action to do so.

Number 2, (assuming a human launcher) the release of the model by the launcher must be consistent, complete and in no way apply any purposeful  "leverage" to any part of the airplane.  My definition of "appropriate restraint" is that the ship is restrained prior to launch "only" by the right hand fingers slightly (one digit of the four fingers) around the leading edge roughly halfway out the right wing half span.  The left hand fingers are "placed" on the left/inboard side of the vertical stabilizer/rudder.  Neither hand is "grasping" the airplane.  Thus restraint is accomplished by the right fingers over the leading edge of the right wing and the left fingers merely restraining the aircraft from pivoting around the right wing restraint.  The airplane/power-train is thus restraining itself.

The beauty of this "restraint vice holding" method is that, when the pilot signals for the release the launcher needs only to  simultaneously lift his left and right fingers off the surface of the right wing leading edge and left side of the rudder and the airplane simply rolls away on the desired track (assuming the pilots has properly placed himself (see #1)

Ted

« Last Edit: May 05, 2021, 05:38:38 PM by Ted Fancher »

Online Ken Culbertson

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Re: Loose Lines Sink Ships
« Reply #10 on: May 05, 2021, 10:13:17 PM »
The only thing I do other than making sure the plane tracks straight when you roll it is to make the inboard gear slightly longer than the inboard so that the plane is in line with the lines when it starts it's roll and I don't have to do that Crouching Tiger stance.  It also makes the takeoff easier since the inboard wheel is not lifting early.  I only brake the outboard wheel and that helps if you need some quick yaw.  I almost never use brakes in competition but they are useful in practice.

You have very little aerodynamic control for the first 5-10 feet of the takeoff roll, even more if you have a slow ramp up electric. (personally I like the slow ramp up because it is more realistic.)   If you are not careful the motor's torque is going to roll it in on you as soon as it has any lift.  Reversing the prop's rotation greatly improves takeoff but IMHO that is about all it does for you.  I lead the ship as it is gaining speed by walking ahead of it and keeping the lines tight until I feel the controls take hold, then I stop and start rotating.  I use the Gieseke long tail wheel setup so the plane literally takes off (and lands) by itself.  Ground effect will lift it a couple of inches when it is ready and you will have full control and trim.

Since most modern PA ships don't have takeoff issues if properly trimmed you might get an All American Sr. for OTS and practice on it. ~^

Ken
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