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Old Oct 26, 2011, 10:48 PM
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United States, OR, Corvallis
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Great Planes Spirit 2M woody with LOTS of modifications and REPAIRS!!!.

So, here's what I have going so far:

The airfoil was, umm, cough, modified due to some overzealous sanding at first, so I went ahead and just lowered the bulge forward of the main spar in the whole wing by a smidge and extended the 'Philips Entry' back to the main spar but did not increase the elevation of the leading edge.

My goal with this plane is to attempt to actually build it down to somewhere near the weight listed on the box, or less, for a change, and increase speed/penetration aerodynamically more than with weight. I do plan on adding a ballast container of somesort if it looks like I can achieve that goal.

I plan on sheeting the forward section of the wings all the way to the tips per recommendations, as well as putting a smidge of built-in washout in the tips. Plus, I'm significantly increasing the spar webs on the inner portions of the main wing.

The Elevator/horiz stab incidence relative to the wing will also be reduced and the Rudder/Vert stab will be either enlarged, moved rearward, or both.

Hopefully I'll be modifying the fusalage in a weight reducing and drag reducing manner as well, but we'll see what happens when I get to that point. I have several ideas brewing but again, I'll see what happens at that point.

QUESTION: How much do I really need spoilers in this plane? I can generally land my 2M Easy Eagle fine(no spoilers). If anything, the Easy Eagle has made me really appreciate having flaps to slow down and get more lift in thermals. But I digress, since I really want to be light and be able to fly somewhat slowly when wanted and have as clean a wing as possible, Will spoilers really do "that" much for this plane to counter the extra weight and aerodynamic messiness that comes with adding spoilers to a 2M wing??? I'm quite confident I can put them in later If I find that this plane stays in the air too long(though I do know well that it would be easier to put them in during the initial buildup).

Thanks - Paul
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Last edited by Pauliwog; Sep 19, 2012 at 10:11 PM. Reason: Clarification.
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Old Oct 27, 2011, 12:48 AM
planepainter
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Mt. Juliet, TN
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I land mine without spoilers just fine. You get used to it. If you could keep the weight down on other parts of the plane you could get away with spoilers. But I think they just add weight. JMHO. If you get into a boomer thermal you could always spin out of it. Thats what I do.
Don't suppose there is a way you could add at least an inch to the fuse length? I know you are building from a kit but believe me the fuse could sure use a bit more length. Good idea with the wings. That is what I did.



PP
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Old Oct 27, 2011, 01:30 AM
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USA, CA, Roseville
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I recently did extensive mods on my Spirit 100. My mods were mainly centered on lightening up the ship for better thermalling. I think the airfoil is going to dictate your speed if you don't want to regulate it with weight.

Also I've done some spar testing and a lighter way to add web strength is to add 1/16 balsa to the side of the spar not the center. The weakness is always at the glue joint not the materials and the C-beam has a stronger glue attachment. (I hope it is't too late)
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Old Oct 27, 2011, 10:18 AM
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United States, CO, Colorado Springs
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I always want big spoilers or landing. I hate going without-- so I found the stock Spirit spoilers to be too small for serious landing help. If you're like me, make them 5 bays instead of 3. If not, go without.

+1 to tail boom length if you can manage it.
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Old Oct 27, 2011, 12:23 PM
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Bedford, TX
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Hi Paul-

Looking very good! It sounds like you've done your research on the Spirit and you will have a good flying plane. The Spirit 2m is what I learned on and love to fly. The mod that made the biggest impact for me was to shave down (3/32" towards the rear) the stab mount to bring the incidence more in line the wings geometric profile. If you sheet the wings to the tips, I don't think you'll need to build in any washout, you can blow some in later if needed.

Spoilers are great to have on this plane as it does fly a little fast and are easy to install. A pull string setup doesn't weigh that much and there is room up front to mount the servo. Here's a pic or two of how I did mine. The line run up and over the front dowel which is covered with very slick Teflon tape. After 5 years, they still work very smoothly.

Best of luck on your build!

Don
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Old Oct 27, 2011, 09:57 PM
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United States, OR, Corvallis
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Thanks for the input!

PP- Yes, I do plan on adding at least 1" to the forward(nose) end of the fusalage to need less additional balance weight. I also plan on moving the rudder/vert stab back. My Easy Eagle has a shorter wing-to-horiz stab/elev distance than the Spirit so the Spirit should be a litte tamer by comparison as it is, but i still may extend that distance also. I definately plan on fusalage modifications(narrower, longer, less tall), I may even follow some of your lead with a pod-n-boom similiar to what you were doing with one of your planes(your Spirit and maybe your extended wing Sig Riser 100???)

So far, getting into boomer thermals has been the real challenge and getting out of good ones has not been a problem yet, the only slight issue has been having enough penetration to sail back into the wind after drifting up up and downwind, and so far that heavy 38oz Easy Eagle has done well with that task. I don't think I would want spoilers and their extra drag to get out of a thermal and back home, I would be pretty much using them just for landing in areas of limited size more than anything.

DWELLS- Yep, I'm thinking that if I do put in spoilers, I'll likely use a string-pull arrangement with one mini or micro servo in the fusalage as you had pictured if I can keep the frictional resistance down on the string to not overload the servo. Also, I like the way your control horn and the notch are different (and better in my opinion) than what I see on the plans I have, I'm guessing there is a rubber band of some sort that I'm seeing that you are using as a tension-closure device?

Yes, I remember you also mentioned the incidence mod in the horiz stab awhile ago which agrees with several others who all did similar amounts of change from 1/8" to about 3/32" as you did. I definately plan on doing that since I did something similar(about 1/16"-ish) with my dinky 37" Guillows Arrow glider mod and it made a big difference in getting rid of bouncy occillations

RDEIS- I did some reading by Ray Hayes on the Skybench website and other places on the internet on the spoiler topic and he and someone else(Thornburg??) actually go narrower in span of spoiler than most and recommend making the leading to trailing edge "chord" of the spoiler longer rather than span of the spoiler wider to keep a cleaner wing and better complete closure of the spoiler. Also, I read where someone moves their spoilers as far back toward the trailing edge as "legal" for competition to keep things aerodynamically clean as possible so I may go that route and put the pre-cut notches back into the ribs and cut new spoiler notches farther back than per plans. Also, in addition to adding at least an inch to the nose, I have wondered about a little more length between the wing and elevator/rudder too so that good you mentioned that.

HASSELBLAD7- I remember someone doing a pretty thorough spar-break test experiment with a lot of different spar configurations/sizes, if that was yours, that was really well done. If not, thanks for the new input. What I'm probably going to do is keep putting thick in-between-the-spars type of shear webs for compression for the first few rib bays, then taper to thinner similar shear webs farther out distally to the thicker inner webs , and on both of what I just mentioned, put single or double "outer" 1/16" sheer webs that came with the kit for a better tension glue joint as you mentioned, then go to just the single "C-beam" type as I go farther toward the tip as you mentioned and per plans on the outer sections of the wings. That is more or less how my Ace Easy Eagle wing is built and it has been QUITE rugged and nice and stiff for nice launches and tight turns and backflip loops, not to mention - a LOT of early really messy landings involving wingtips, in fact I was soooo good at doing it, I proposed that spot landing criteria be changed to wingtip landings rather than lawndarting the nose for max points. OK, just kidding on that one.

Oh, and here's my handy method of cutting "between-the-spars" spar webs by using the aluminum center dihedral brace as a measuring jig to mark the wood and use as a guide for slightly oversized pieces that I just sand a little for a good fit.

Thanks - Paul
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Last edited by Pauliwog; Oct 29, 2011 at 02:28 PM. Reason: Clarification
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Old Oct 27, 2011, 10:06 PM
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Lindenwold, NJ, USA
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About a dozen years ago, I went to a local 2 meter contest. There was a 'different' looking plane there so I asked the owner what it was. Turns out that it was a Spirit wing mounted on a Gentle Lady fuselage. The GL fuse is lighter to begin with and this guy even had pull-pull control for the rudder and elevator.
He won the contest.
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Old Nov 03, 2011, 06:07 PM
Wood Chucker
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USA, TX, Allen
Joined Nov 2009
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Mark Drela shared a good method for cutting sheer web to high accuracy.

http://www.charlesriverrc.org/articl...webcutting.pdf
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Old Nov 03, 2011, 10:00 PM
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United States, OR, Corvallis
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Spar web cutting jig......

Hey, I saw that posted somewhere at least a year ago and forgot all about that.

Good idea, Thanks for posting that! - Paul
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Old Nov 09, 2011, 12:03 PM
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Farmers Branch(Dallas) Texas
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Spirit 2M

This was an interesting read that all of you guys posted to. I just ordered a Spirit 2M from LHS. I had one about 20 years ago and disliked it to the point of giving it away to some "unlucky" soul.
Spoilers: I have had spoilers on only one 2M, and it was a Gnome from Midwest Models(???), my memory fails me at times. With me it was always full up elevator and hard right or left rudder, those flat spins downward are a bit spooky but it works.
I will incorporate suggested mods as I build the Spirit. Has anyone lenghtened the fuse behind the wing(did I miss that in the posts?) or is it just move the Vert and Stab back abit? I am not sure but my mind is telling me(a dangerous situation) to add 2 or 3 iinches to the fuse behind the wing???

Thanks for all the great info posted here.
Alex
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Old Nov 09, 2011, 12:52 PM
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Bedford, TX
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Alex,

There's a lot to consider if you lengthen the fuse. You'll have a great flying Spirit if you do these mods http://charlesriverrc.org/articles/k...spiritmods.htm .

Cheers, Don
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Old Nov 09, 2011, 05:20 PM
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Spirit fuse elongation!!

Hi Don and Thanks for the tip. I was considering lengthening the fuse a bit because it seems/appears to be very short coupled. I am not much of a theory guy when it comes to aircraft design, come to think of it I may not be much of a flyer after 33 years of SP'ing!!! Maybe I shouldn't mess with that portion of the aircraft as I'm not certain what happens with an increase of 2 or 3 inches between wing and stab on top of the other mods.

How's the Sophisticated Lady coming along? Started??
Alex
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Old Nov 09, 2011, 05:49 PM
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Bedford, TX
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Alex,

Didn't realize it was you! Yeah, if you lengthen the standard fuse construction and do the tail feather mods (which are more critical) you're going to have a heavy Spirit. The fin/rudder enlargement and shaving down the stab saddle will make a big difference and rid of the Spirit wobble. The SL is actually on the bench now. I've found some issues with the laser cutting (actually programming) that is minor but nothing that can't be sanded into shape. I think it well be a great model once I'm done.

Don
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Old Nov 09, 2011, 10:30 PM
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Wings thus far.....

Getting there......

FUSALAGE ELONGATION??- Yes, I am probably going to try to add 1-2 inches to the fusalage behind the wing, and at least 1 inch in front of the wing so that I can use batteries, servos and such for most of the balance weight and add as little balancing weight as I can get away with since I now have slightly thinner airfoil (and faster) plane, so I would like it to come in under-weight if possible so it's not a complete lead-sled and penetrate by aerodynamics more than by weight.

Also, I want to try to make it narrower and less tall, and maybe completly redone with a round/oval cross section, maybe, just maybe. We'll see how motivated I am at that point.

Adios- Paul
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Last edited by Pauliwog; Nov 09, 2011 at 10:35 PM.
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Old Nov 16, 2011, 12:06 PM
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Paul:

If you lengthen the fuselage behind the wing, you will negate the added length in front. You will most likely need additional nose ballast for CG purposes. Anyting you do behind the CG, typically calls for about 3 times the weight in front of the CG for balance purposes.

What you can do to enhance control (and stabillity), is to make sure your tail surfaces are tapered in back, rounded in front, for an "aerodynamic" shape. Flat plates just do not cut it for drag, and tapering removes (guess what!) weight.

In all my 2-meter ships, plus a selection of Riser 100s, I hinged the spoilers at the rear of the wing spar. Too far aft, and they are buried in the boundary layer. I found that a spoiler span of four ribs' worth was adequate. I built at least one 2-meter ship in two versions: spoilers, and not-spoilers - there was no discernable penalty in carrying spoilers and the associated servo. Pull strings to a fuselage servo works for me, every time. I use spoilers for glide slope control on landing - leaving boomers, it is more effective to spin/loop/dive/what-have-you.

More than you asked for, I'm sorry.

Yours, Greg
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