Legend4

Hello

I am about to get started on my Great Planes Spirit. I am wondering if it is worth putting in the spoilers and if there is any other tips you would like to share. Thank you.

Roderick-RCU

Hello

Spoilers are fully recommended, If it's true that for beginners are quite a challenge to handle, It's also true that they are a very good help in windy conditions or in short landing situations.

I recommend also, try to mount them with a springer attached to it in order to flush them with the wing shape when closed and as a help to close when openned.

Roderick

Ollie

Spoilers mounted just behind the spar have to be fitted very precisely to prevent disrupting the flow over the wing even when closed. Any appreciable warps, bumbs or gaps will degrade performance some. It is best to locate the spoilers farther aft at about 65% of the chord from the leading edge, where the boundary layer of flow is thicker and small discontinuities are less likely to disrupt the flow.

Here is what Dr. Mark Drela has to say on the subject:

"A hinge bump or edge gap will cause additional drag in several ways:

1) It might trip the flow early. For this not to happen, the glitch must be considerably smaller than the local boundary layer thickness. This is not much of an issue on the AL spoiler, where the flow is either turbulent, or about to undergo transition anyway.

2) The step will cause a thickening of an already-turbulent boundary layer. But if the height is less than 10-50% of the BL thickness, then you will see little effect. Where in the 10-50% range you can be depends on...

3) The local velocity just above the step relative to the freestream. The lower this velocity, the larger the step can be without causing significant losses. The absolute worst place for a step, or any proturberance, is on the front 1/3 of the airfoil top surface, while a step near the TE is relatively benign. This is why my AL's front wing bolt head is buried, and the rear one isn't.


The AL's spoiler TE is at 65% chord, where the flow is turbulent (at high CL) or about to undergo transition (at low CL), so tripping is not much of an issue. At a mid-range CL, the local boundary layer at 65% chord is about 0.4" thick. If the spoiler TE is lifted off the airfoil less than about 0.06", I won't worry about it. If the spoiler was mounted off the spar, I would worry about a 0.01" glitch.

- Mark"

Gary Retterbush

Unless you fly on a postage stamp sized field, forget the spoilers. I have built and flown several 2m and 2.5m (edited: Spirits) and spoilers are not worth the trouble IMHO. Inverted flight will help get you down out of strong thermals if necessary (99% of the time it is not necessary).

Beef up the wing joiner with high grade aircraft ply and/or carbon and be sure the joiner box is well wrapped.

soar-iowa

My Feedback: (9)

I would add carbon to top and bottom of spars. Like .007. It really helped mine on winch launchs'. I would add spoilers. If you don't use them you could always tape them down. It's darn near impossible to add later. Good luck!

Legend4

Thank you everyone for your advice. I will use this well given advice for my project. I am looking forward to this non powered flight thing. I find it amazing how you can fly for so long with out an engine or motor. Till then happy flying.

Ollie

Long thermal flights are all about energy managment. The glider is always loosing potential energy due to its sinking speed. In a thermal that is rising faster than the glider's sinking speed the plane is lifted for a net gain in potential energy. Flying slowly, just above the stall, in a thermal maximizes the rate of potential energy gain. Flying fast between thermals minimizes the rate of potential energy loss. Developing the skill to fly smoothly at a variety of airspeeds is an essential skill for long thermal flights especially when returning to the field after chasing a thermal down wind.

Teaching yourself energy managment is enhanced by trying to land precisely without the use of spoilers. Every landing without spoilers is practice that speeds the development of thermalling skills. The final approach glide path into the wind is stretched by flying faster and shortend by flying slower. In this way the glide path can be controlled on landing approach.

My recommendation is to avoid the use of spoilers until you have the ability to consistently get long thermal flights or until you need them for contest landings.

Cerberus

Here's something that may be of interest to you .

www.charlesriverrc.org go to the search feature and type in Spirit all the best, John

TomM

I'm building my third Spirit. Didn't need them all at once. First I needed a new wing, then a new fuse, then a new wing again, then an electric fuse - you get the picture.....
I built the first wing with spoilers and never used them.


Some things I can think of even though it flys great out of the box.

If you're building the 2 piece wing, make the joiner boxes STRONG. Wrap the spars with plenty of dacron thread, using a drop of CA every 4-5 wraps to keep it tight, and then cover with some good 30-45 minute epoxy. Paint some epoxy on the inside of the shear web joints for the inner 4-5 bays.

The inner plywwod that re-enforces the tow-hook blind nuts.....
get a new piece twice as long and twice as thick. The blind nuts need something a little thicker to really seat themselves, and I also worried that the nut might pull through on a strong winch launch. Maybe not.

Increase the chord of the elevator about 3/4 to 1 inch. Nothing critical, I just think it makes the response sooner and smoother.

My free finishing advice- worth every penny you paid!

Don't bother covering the fuse with iron-on film. I could never get the pointed nose to look good. After you shape the nose block, paint it with some thinned-down wood filler or putty, then sand it smooth again. Get the cheapest sanding primer spray can from wallmart, 3 coats ,sanding the last 2 with 220 grit, and then the cheapest spray can of paint over it. Make sure you put some masking tape over the stab gluing area. After it dries for 2 days, glue the tail on.

Tom

aeajr

My Feedback: (2)

Link to a great thread on Spirit spoilers.

http://www.rcgroups.com/forums/showt...5&pagenumber=1

aeajr

My Feedback: (2)

This business of reinforcing the wing joiner has me a little confused. You are refering to the piece that slips into the wings to set the angle, right?

I have heard people say the glass this. Do they mean the glass the joiner, or that they glass the wings together. I presume they cut away the covering and wrap the inner part of the wings together with the joiner in place.

Does anyone have a photo of these wing joiner reinforcements? I am trying to understand. I like the idea of being able to take the wings apart, but I will want to winch launch, thought I am sure I can just go easy on the pedal.

TomM

For a 2 piece wing you glass the "boxes" you made where the ply wing jointer slips into. Before you sheet the root/center section, wrap Dacron/nomex thread TIGHTLY around upper and lower spar. (slip the ply jointer in there to mahe a tight fit- don't glue it in!)Then you either brush on epoxy resin or soak in some thin CA. (the jointer should be out now!)


Wrap with no spaces- similar to a line guide ferrule on a fishing rod.
Tedious but real cheap and simple. The other way is to wrap glass cloth around the box, but I can't get it as tight as thread.

When finished sheeting and prepping for covering- don't sand away the thread..