stretch

I've been flying my Spectra electric sailplane for about 3 months now and would like to add some type of air brake to slow it down for landing. I fly at a smallish field near my home sometimes and have to come in steep to avoid a tree line. The Spectra picks up a lot of speed and I would like to bleed that off faster.

I have upgraded it a bit. Using a 2.8/1 Geared Speed 500 motor and 11x8 prop. Also using an Eclipse7 Xmtr with a SuperSlim receiver.

The wing is 2 piece, held in place with rubber bands.

Has anybody made this type of modification before? Anyplace on the web that might have instructions?

Thanks,

AJ

dedapr

dedapr

The Great Planes Spirit model is identical to the Spectra, but w/out a motor. The winds are identical and interchangeable (I have both) except the Spirit has spoilers.

If you go to the great Planes site and download the manual for the Spirit you will see how they did it. You probably could duplicate the set-up on your Spectra. The only problem I see is the Spirit has a hollow tube that goes thru the wing that you run the fishing line that operates the spoilers.

Hope this helps.

Steff

The manual for the spectra says on page 10: do not punch out the notch for the spoilers in the W2S ribs.

I do not understand why they do not at least give he builder the option. I would love to build the spoilers in, especially since most is prepared.

They should work on the Spectra just as well as on the Spirit am I right?



Cheers

Steff

Mike P

My Feedback: (2)

Stretch-
Would you describe how you did your two piece wing held with rubber bands? My spectra ARF wing is a pain to transport and I'd like to make it a two piece. Thanks.

wildblueyawner

Spoilers or flaps alone aren't as effective as having both working together for glide slope control. Spoilers reduce lift and increase drag, but also increase min stall speed. The reduced L/D enables descending at a relatively steep angle, but airspeed will increase - it just won't increase as much as if you descended along that same angle by applying down elevator. Conversely, flaps reduce speed due to increased Cl, causing the plane to float around or get buffeted if the wind is up. Rapidly pulling flaps up on final can also lead to a low-altitude stall = damaged plane.

Combining flaps and pop-up spoilers (or the next most-effective thing ==> Crow) offers the ultimate glide slope control due to the conflicting effects of the two methods.

I prefer spoilers directly driven by servos (e.g. Hitec HS-81, HS-55) mounted in the wing - enables precise adjustment of the closed position, avoids the slop of a long linkage scheme, and no need for return springs, rubber bands or weights.

There are some key points to keep in mind when installing or retrofitting spoilers - If interested, let me know & I'll post some suggestions.

Steff

Don't take that wrong, but that does not help me at all. The Spectra is a RE or RES ship. With plenty dihedral, no ailerons or flaps.

The not electric version, the Spirit, does have the option to be built with spoilers. The Spectra comes with the same rib set, yet the instructions specifically say do NOT cut out the notches to build the spoiler.

What I do not understand is : how are spoilers different in the electrified version? It is pretty much the same plane as far as I know.

I intend to build them because I read in this forum in several postings that hey are helpful, in tis plane too.


Steff

wildblueyawner

Sorry :stupid: I should've paid attention to the rest of the thread where the Spirit is mentioned.

Getting closer to your point, there's more reason to use spoilers or airbrakes on an electric glider than its non-electric version, because the electric will fly faster (assuming same airfoil and wing area) given its higher wing loading.

The recommendation to not remove material from the ribs is probably based on a structural concern that, to me, doesn't seem like something to worry about - An e-glider doesn't get hi-started or winched, which is when a regular thermal glider's wings see the highest stress - way more than normal flying. If a non-electric glider can handle hi-start launches, then the electric version with a few rib notches can surely handle the slightly higher stresses of the higher wing loading.

If you're flying in confined areas, I'd seriously consider installing spoilers - You will notice a big difference

Steff

Thank you, that DID help

I think I will install the spoilers. I see no reason why not. I see a few reasons why I should.

I want to keep the option open to fly in any area I want and land even if the space is confined.

I also agree that a electric version because of the higher wingloading may need the spoilers even more than the lighter unmotorized one.

Finally, if installed right they will not create a disavantage ( well, maybe a little more weight with an extra servo ) and I have at least the option to use them if I need to.

I thought firts that I will not need them to get out of a thermal since I have the electric engine. But I will need them to land in a confined area.


Thanks

Steff ;}

wildblueyawner

The thing to be conscious of when installing spoilers is ensuring that they're as flush as possible with the rest of the wing in the closed position.

Spoilers are typically installed near the high point of the wing's top surface - this location is critically important, where little surface imperfections like bumps or gaps can cause premature flow separation and high drag.

I ALWAYS use gap seal/tape around spoilers (and every hinged control surface for that matter) to make them as aerodynamically clean as possible - Low drag is what makes a glide flat!

aeajr

My Feedback: (2)

wildblueyawner


Not familiar with gap seal tape. Can you describe it and where to get it?

wildblueyawner

Gap tape is basically thick scotch tape having adhesive on only half the width of the tape.

The sticky side is applied to the surface ahead of the hinge line, and the free (non-sticky) part covers the hinge gap. It's a simple way to reduce the drag at hinge gaps while still allowing large deflections. And for surfaces that are hinged with actual hinges instead of hinge tape, gap tape prevents air from blowing through the hinge gap which reduces control response.

Gap tape is available from NSP Gap Tape and Hobby Lobby More Gap Tape , but I make my own because the commercially-available tape is stiff and often presses on the control surface to the point where the servo has to fight it.

Some who have made their own gap tape said the tape would deteriorate after a season of exposure to sunlight / UV. I suspect they're using plain scotch tape, the kind that has a frosty appearance (3M Magic Tape), which is NOT the stuff to use. The best stuff IMO that's easy to find is 3M "crystal clear" or "multi-task" glossy scotch tape. It holds up well and it's as close to invisible as you'll get.

To make gap tape, besides the scotch tape, you'll need a clean cutting surface, e.g. glass or plastic sheet, a razor or sharp knife (my favorite for slicing any film or covering material is the curved Xacto #10 blade) and a metal straightedge.

I make gap tape in pieces about a foot long max, since it's difficult (for me) to apply longer lengths without getting it twisted or folded, or accidentally stuck to myself or the tabletop, etc.

3 strips of tape make 2 pieces of finished gap tape. See the sketch - Tape-down the ends of a piece of tape (Strip #1) sticky-side UP - don't stretch it, use only enough tension to keep it straight, otherwise the finished gap tape will curl or have waves in it. Then take a piece of tape (Strip #2) and apply it sticky-side DOWN onto Strip #1, overlapping the strips per one of the shaded areas in the pic. Again keep the tape straight by applying only very slight tension. Repeat with another piece of tape (Strip #3) leaving a small (1/16") gap between Strip #2 and Strip #3.

Then slice Strip #1 along the gap between Strips #2 and #3 and voila! - 2 lengths of gap seal, ready to apply

My first attempts were tricky - takes some finesse to handle the tape strips and get them placed reasonably accurately.

aeajr

My Feedback: (2)

Thanks! A great idea!

aeajr

My Feedback: (2)

The planes may be the same overall, but are the spoilers built into the wing of the spectra as they are on the Spirit? The spirit has them sitting under the covering. You just cut them out and run the control wire.

If the spectra wing does not have the spoilers built in, you could buy a Spirit wing and just swap them after you put in the spoilers. This way you don't have to be concerned about making a change to the wing. If it doesn't work well with spoilers, just put the original wing back on. Costs more, but prevents a problem with the original wing.

Just a thought.

marzouin

Hello ! I'm bulding my second spectra.

I have buy my firt when I was in secondary 2, I remplace de stock motor by a master airscrew 550 motor with a 2.5:1 gear box with a 12 x 8 prop and a 7 cells 1200mha battry, even if its more powerful, I find that he does not have enought power

Now I bulding a new spectra, I remove the dihetral in the ends of wings, I put flapron with two hitec hs-81 servo, I remplace the stock motor for a graupner speed 700 direct drive and a 10x6 prop and a 8 cells sanyo 3000 mha battry...

to add aileron, simply remove the trailing edge to the lengt you whant you flap, remove aproximatly 3/16 of the ribs in front of the t/e, glue a 1/8 sheet of balsa on these rib, do a system to move your flaps, do a servo hole, recover it, and that all !

please sorry my poor english....

Pierre