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-   -   Semroc Swift (http://www.oldrocketforum.com/showthread.php?t=17376)

MarkB. 07-08-2018 08:21 PM

Semroc Swift
 
Comrades:

I am building my first Boost/Gliders for my NARTrek Silver. I have a Fly Baby from Chas. Russell plans that he posted when I mentioned this earlier this year; I'm almost done. I am also building a Semroc (formerly Centuri) Swift as a backup. Never having done this before, I have questions:

1) Finishing - a clear coat of dope on the wood followed by tissue doped on top? How long do I wait between the coat on the wood and applying the tissue layer? I'm using SIG butyrate dope; it's all I could find. I have various colored tissue from SWMBO's hoard.

2) The Swift has a tube that is supposed to slip fit over the engine hook on the pod. The little tube will slip fit over a BT-20 but not over the ST-7 that came with the kit. Or did I mess up somehow?

3) Seems like the booms and perhaps the elevators are fairly close to the exhaust plume. Does this need to be epoxy coated?

4) Are the engine pods painted?

5) On trimming, how big a left hand turn am I looking for?

Other suggestion?

ghrocketman 07-08-2018 10:31 PM

No tissue over the dope for a boost glider.
1 coat of sanding Sealer, then 1 coat of thinned color dope followed by a thin coat of clear would be lighter than using any tissue.

astronwolf 07-09-2018 07:45 AM

1. I've built and flown this kit, and I didn't bother tissuing it because I was flying it at a meet. I just colored it lightly with florists spray paint. But tissuing adds some strength and durability, and if you want a keeper, tissue it.
https://www.nar.org/wp-content/uplo...ngs-Vandall.pdf

2. I don't know. Write Randy Boadway a note and ask. Maybe you got the wrong part. You could also lengthwise slit the ring/tube that goes over the engine hook. It will slip fit then, and glue it down. Works the same.

3. No. No epoxy coat. Tissue it.

4. Paint the engine pod a fluorescent orange or green. Or something to make it more visible. They are very easily lost.

5. I'd shoot for 20-40 foot diameter circle. Here are some guides:
http://www.nar.org/contest-and-reco...-trimming-tips/
https://www.nar.org/wp-content/uplo...ders-Newill.pdf

6. EXTRA - don't fly this thing with a B motor. That's just my opinion and recommendation. I'd fly this with 1/2A to A motors.

ghrocketman 07-09-2018 10:45 AM

Tissuing adds a significant weight penalty over just dope.
If you want best fight times, skip the tissue.
I do agree it will add durability. So would using iron-on Monokote for the wing.

Chas Russell 07-09-2018 11:08 AM

I am in basic agreement with the comments above. I tissued the original Fly Baby for strength in case I ever tried it with a C motor. You can use at least one coat of sanding sealer and color the surfaces with wide tipped markers. I usually use black on the bottom (with red or orange at the tips) and red or orange on top. If you fly bare balsa you risk warping from wet grass.

The mylar ring was apparently the wrong part. Slit it or replace it with a piece of body tube or even paper. The only purpose is to help hold the motor hook down. I always tape the hook to the motor and pod tube. Just don't block the launch lug.

A thin coat of CA will help to protect the top of the boom, but is necessary only in front of the wing. I use a strip of silver adhesive monocoat on top of the wing and replace it as necessary.

Good references on glider trimming.

Fly Baby with a B. Swift with an A. 1/2A's are good, but have a killer ejection charge.

I either paint the pod red or orange. Been using markers more and more. One tip for the pods is to use an external kevlar shock line glued to the tube/pylon junction on the opposite side of the launch lug, if the lug is mounted at that location. Tape the kevlar at the ejection end of the, but at the top of the tube (assuming that the launch lug is not on top). This aids in the separation of the pod and helps to prevent the streamer from possibly grabbing the glider. Matt Steele made that change and it has worked well.


Most of all, have fun.

Chas

Chas Russell 07-09-2018 11:17 AM

1 Attachment(s)
Well, this photo somewhat contradicts one of my comments about the Kevlar line attachment, but it does illustrate its attachment.

Chas


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