Spirit 100 wing ?

[hs748]

Satrting to work on my Spirit 100 kit.

What would be the best option for the wing? I'm not into any competition flying, just casual, relaxing type flying!

Thanks,

Jarrett

[rdeis]

The big Spirit flies nicely with all setups, but you don't want a large sailplane without some sort of glide path control.

Sport wing with Spoilers will give you plenty of "relaxed" soaring.

The advanced wing will give you a new level of options and performance to explore- camber change is fun!

[Rob Nelson]

Keep it simple. Poly wing with spoilers. Even if you don't go the spoiler route, include tubing and all the good stuff for mounting spoilers... Then you can then easily add them later if you desire.
A little off the suject...I believe Great Planes has included in the kit, on a separate sheet of paper with suggestions for strengthening the spar and joiner. I had this kit at one time, but traded it in for an Olympic 2...I remember looking at these suggestions, and they sounded like a good idea. I know the stock spar webbing on the Spirit are 1/16" sheet glued to the side of the spar...Don't recall what the Spirit 100 calls for. I would definetly use webbing the thickness of the spar to the ploy joint, then step the thickness of the webs down towards the tip. Ensure the web's grain is oriented vertically and fitted between the top and bottom spars...not on the edge.
Hope this is of some help.
The 748 looks good.
Cheers,
Rob in YYZ

[jrgospod]

rdeis

Just in case Jarrett does not know, the spoilers will cause the plane to loose altitude (lift) but not slow it down significantly. For a long time I was under the impression that spoilers would also slow down the forward movement. Not a good assumption.

John

[Ollie]

Spoilers narrow the speed range. The reduction in maximum lift coeficient of the wing raises the stalling speed. The increase in drag coefficient steepens the best glide angle and reduces the terminal velocity in a terminal velocity dive.

[rdeis]

Originally posted by jrgospod
Just in case Jarrett does not know, the spoilers will cause the plane to loose altitude (lift) but not slow it down significantly.

I've seen that said on this forum several times, now. (Over on the electric side, too) but it doesn't meet with my experience.

When I open the spoilers usually add a little up elevator to keep it from pitching over, and she slows way down and picks up a steep glide slope.

Maybe it's becasue my spoilers are huge- or maybe I'm just misperceiving things. In either case, I get what I want, which is a steep, slow, controlled descent to the spot. <shrug>

They do have different effects depending on how far they open, I guess. Mine go 90 degrees to land, but occaisionally I used to crack them just a little to race out of sink.

[Ollie]

rdeis,

Your experience is true, its just your interpretation of the facts you observe that needs correction. Your plane is not flying at its minimum air speed just above a stall when you open the spoilers. If your plane were trimmed to fly at the slowest possible speed and you opened the spoilers, the plane would slow even farther and immediately stall. Even so, you can get your plane to fly at its slowest by carefully adding one click of up elevator at a time untill the plane stalls and then remove one click of up elevator trim and fly it that way. It will fly slower than if you first open the spoilers and keep adding up trim until the plane stalls. Flying with out any stall margin of airspeed is very risky and any gust is likely to upset the pitch trim and possibly stall the plane. The practical thing to do is to fly with some margin of airspeed above a stall. If you fly with the same stall margin of airspeed with the spoiler open and closed the airspeed will be greater with the spoiler open. Because the pitch trim changes when the spoilers are opened, you must have a reliable way of comparing the stall margin of airspeed in the two cases. An air speed indicator (rare in models) is what you need to make valid comparisons.

[rdeis]

Makes sense- most of the time I use spoilers on final approach, and I was taught to fly the landing pattern with a few clicks of down trim for better control authority.

So I'd guess that on final, the plane is a little bit hot, and the barn-door drag of the spoilers combined with the fact that there's plenty of lift at that airspeed dominates any airspeed increase I'd have seen due to increased stall speed?

[Soar_dude]

Build the sport wing with spoilers and buy the wood for the advanced wing the kit comes with 2 complete rib sets. One other thing carbon the spars and sheet the outboard wing leading edges (D tube) if you don't the outboard leading shape will be distorted because the space between ribs is wide and flattens out the airfoil which will cause it to be a tip stall monster.

Just my 2 cents PM me if need anymore tidbits to help out

Soar Dude

[Ric Duley]

Build it light - this plane can get heavy in a hurry.......