Spirit Kit - Any building advice?

[aeajr]

I just destroyed my Great Planes Spirit Select, an RTF package, that I have really enjoyed for about 60 great hi-start launches. I was learning how to use the club winch, got a bad launch, panicked, and put the plane into the ground very hard. Anyone need some tooth picks?

So I am going to build a new one from a kit. This is my very first kit, so I would appreciate any advice on building it.

Are there any pieces or places in the build process where I should deviate from the plans to reinforce the structure? I plan to build it stock, so I am not looking for modifications to the plans other than to improve the strength or to reduce the weight of the structure where appropriate.

I will be keeping the wing as a two piece wing. My habit was to tape the wing halves together with clear packing tape. The wings never fluttered on the strongest hi-start launches, even in 15 MPH winds. My NE Sail planes hi-start has 1/2" tubing and easily launches 3 meter+ planes. I get very powerful launches.

While the stab mount had been prone to breakage, it was easily fixed and I believed that this breakage probably saved the stab from damage. Sort of a sacrificial release point. Any thoughts on this?

Since I am still a fairly new pilot, I planned to stay with the rubber band wing mount method, but would be open to any alternate ideas.

Any advice on glues or gluing techniques?

Would I benefit from the addition of carbon fiber rod, tube, sheet, cloth or thread for reinforcement at key stress points?

Most of the time it will be launched using that powerful hi-start, but I am planning to do more and more launches using the club winch, so strength is important to me. I don't expect to zoom it, but since this is a new build, now is the time to consider reinforcement or enhancement to the structure.

I will be building in the spoilers using servos in the wings. I had recently added the spoilers in this fashion to the Spirit Select and really loved the way they helped with landings.

I will be covering the plane with Monokote.

Just for background, in addition to the 60 Spirit launches, I also have about 100 flights on an Aerobird electric parkflyer and about 20 flights on an Electrajet delta wing park flyer ARF foam kit that I built.

Thanks for any tips you may be able to provide as I start building my new sailplane.

[Dave Robelen]

Hi,
I have never built the Spirit from the kit, but there are a few useful guidelines of a general nature. Considering the strength and success of the ARF version, structural mods are probably less needful here.
Good building technique can be a key to strength with the lowest weight. Never be satisfied with joints that have a visible gap, the wood parts need to fit tighly all across a joint before applying glue. The CA glues are nice when you can work fairly quickly, but there are other options for a wood model. I am fond of Elmer's Carpenters wood glue. It is amply strong with balsa, and the slower drying time is a bonus in getting things to line up before the glue sets. It is awfully easy to use excess glue on a structure. If you can see visible fillets of glue in corners and such, it is time to cut back on the glue. Glue that is spread around a joint adds little strength, and noticeable weight.
A key tool is a good flat sanding block, better yet, several with different grades of paper. About the only time it is suitable to sand with a loose piece of paper in your hand is working on a paint finish. I am fond of making my sanding blocks from 3/4"-1.0" balsa. The light weight gives a better feel, and they are not as tiring. Double back carpet tape is great for attaching the sandpaper. Choose the sharpest, most expensive brand in the store. Balsa wood dulls sandpaper very quickly.
Happy building, Dave

[aeajr]

Thanks for the tips Dave.

I had someone else advise a similar glue, but I would have thought that that would be much heavier than CA.

The reason the other guy suggested it was because he felt it was more flexible after drying. Would you consider this a virtue?

The plans call for the use of Thick, medium and thin CA, FYI

[Dave Robelen]

Hi,
I have never seen any weight gain from using wood glue. Te main convenience is the longer working time, and you can spread it thin.
The folks that sell the kit also sell CA. I would expect them to reccomend it. Besides, so many modelers are using it, there is a tendency to "go with the flow".
Take care, Dave

[aeajr]

This thread is old, but I would like to revisit.

Turns out the original spirit was not as bad as I thought. I have been rebuilding it.

Before I put the covering on, another pilot said that if I sheet the front of the wing outer pannels, same as the inner panel of of the wing, that it helps eliminate tip stall.

I am finally up to the point where I can re-cover the wings. I am going to add the 1/32 sheeting to the outer panel of the wing. Do I just lay it on top of the ribs or do I overlap onto the leading edge? Any thoughts on this?

I thought I would just lay it on the ribs with a little overlap onto the leading edge, then sand it to blend it into the leading edge.

Does that seem reasonable?

[Dave Robelen]

Hi,
I would apply it just as you are planning. Lay it right on top of the LE. It is important to get a nice tight joint here, gaps are a problem when sanding. By applying the sheet over the LE, you will have a slightly thicker LE with a bit larger radius. This will definitely help keep the model stable longer at nose high angles. A little twist in the outer panel(TE about 1/8" higher than LE at tip) will also reduce any tip stalling tendencies.
Regards, Dave

[Thom620]

When CA dries Sets its weight is the same as it came out of the jug. carpenders glue is water based so when the water leves it weighs much less. It also penetrates the wood much better for a better bond.
If the wings bend too much on launch (this you can see & or hear)replace the line on your bungie with fishing mono of 20-35lb it will strech at launch and releve some of the stress on the plane.

[aeajr]

If I go to monofiliment fishing line, what weight would you suggest? I am launch a 2 meter Spirit and a 2 meter Sagitta 600 today and will be launcing a 3 Meter Airtronics Legand this summer.

100' test line?

[Dave Robelen]

Hi,
I would use line with a rating from 80-100 pounds test. The lighter line will give higher launches with the 2-meter models, while the thicker material will resist abrasion better. Also, the pull ratings are likely to be lower in cold weather as the line gets more brittle.
Regards, Dave

[aeajr]

Originally posted by aeajr

Turns out the original spirit was not as bad as I thought. I have been rebuilding it.



I did the sheeting on the outer wing as was dicussed above. In fact I think the Spirit will come out better after the repair then when I started. If you are interested, here is a link about it: http://rclibrary.com/viewtopic.php?t=127

[vicjperry]

I heard of the Spirit (which I was building) needing modifications so I started searching online for articles.
I came across this one that explains most of them and have found it to be of great help. Hope it helps you out.

http://www.charlesriverrc.org/articles/kitmods/dickwilliamson_gpspiritmods.htm

Vic

[aeajr]

How is your spirit coming along. I love mine!