Q-talk 2 - Q-TIPS
- Category: Q-Talk Articles
- Published: Saturday, 28 February 1987 06:11
- Written by Jim Masal
- Hits: 1515
From D. J. Harms
For comparing angles which are within a few degrees of each other, the following method using a 24" carpenter's square gives accuracy without having to buy an instant angle finder.
CONSTR: First off, we need a sharp notch near the corner of the square on the 24" leg (see illus.). Next, measure down 14.32" (.3125 = 5/16") on the 16" leg of the square and scribe a line across the face @ 90?. Then, in order to know when we're level, we need a "0 mark" on this scribed line at exactly 90? from the notch made earlier. Finally, mark along the edge of a piece of paper as if making a ruler with the lines 1/4" apart. Between each of the lines, place dots every 1/16". When placed on the square, each line will equal one degree; each dot will equal 1/4 degree. You may want to number this as in illus. for easier reference. Place cellophane tapes over this paper strip and stick onto the square with the marked edge along the scribed line. The plumb line travels from the weight, up the face of the 16" leg, loops through the notch, and is taped on the backside. If you want to use a different size square just decide how far apart each degree mark should be (.25" in my case) and multiply that number times tan 89? which is 57.29 (.25" x 57.29 = 14.32"). Thus 14.32" is the distance from the notch down to the scale.
USE: As shown in the illus., the carpenter's square uses the same leveling strips on the canard and wing as would be used with a bubble level. Now, about the fuselage ...can't use the square on the consoles without inverting the fuselage and anyway, by the time consoles are bonded in place with glass all over them, how level can they be -- and we've been told 1/4 degree makes a difference with this design. What we need is a couple of small holes in the outside fuselage skin, ideally where the fuselage side is vertical and is parallel to the centerline, where cut off nails can be inserted and on which the square can be hung. The holes can be drilled into micro-filled cavities in the foam core making sure they are both on the same waterline. Now the fuselage, canard, or wing can be leveled fore and aft by reference to the "0 mark" or inclined either way by checking the paper strip. Plus, if those fuselage nails are 14.32" apart, then when the aircraft is in 3-point position (on a level floor) and the square is held in the level position while resting on the forward nail, the distance in inches between the square and the rear nail divided by .25 will be the ground angle of attack of the fuselage in degrees (which, according to QUICKTALK #29, pages 2 and 4, is supposed to be 7 3/4? for Q-2's and, who knows, but probably 8? or less for a Quickie).
If you still insist on using a bubble/torpedo level, be sure to mark "FWD OR OUTB'D" with an arrow so orientation of the level is a constant since it's a rare level indeed which gives the same reading when turned 180?.
From John McCluskey - Helena, MT
Be sure to tape up the ends of exposed tubes. I was testing a ram-air vent to my header tank and found that tiny insects had built an impenetrable barrier inside the tube. It was as hard as a rock and necessitated some major reconstruction work.
From Paul Howe - Algonquin, IL
1) Anyone who works in a cold weather climate like we should do what I finally did: get rid of the smoke and stink of the portable heaters and put a good permanent heater in the workshop. Just a flip of a switch and you have a good working environment instead of wasting half your time getting the shop warm enough to glass.
Another thing, I keep my epoxy in the house and wet out fiberglass inside on Handi Wrap and then take it out to the shop - keeps the epoxy at room temp when the shop is not used for long periods.
2) Before I mix epoxy I put old socks over all the doorknobs. Saves a lot of (wife) trouble! I also got the West System Epoxy for finishing. The little bit I've done has sure been nice compared to Safe-T-Poxy.
ED. NOTE: And speaking of wives, we must keep in mind that MORE THAN ONE person lives in the house oft times, so let's be a little bit considerate...or sneaky, at least.
Mike Conlin writes that in cold weather he quickly checks the area for the wife then gives his epoxy about 10 seconds in the microwave (paper towel on top) before he rapidly exits to the garage. (OOOoops, sometimes Bonnie reads this thing). "Almost like summertime working conditions," he sez.
From H. L. Kreighbaum #2230
To prevent having to remove the wheels to check or add air, I drilled a 3/4" hole in the wheel pant in the correct position and by using a valve stem extension I can check or add air. I reinforced around the hole with 2 BID and used an expanding rubber oil pan drain plug to fill the hole. (ED. NOTE: Auto stores have chrome buttons of various sizes to plug such holes also).
From Bob Falkiner
When using X-40 expanding foam, be sure that it is fully cured before starting a layup. This material seems to outgas for several days. This is not a problem until you use it in an enclosed space, like under the LS mod canard. I got some air (gas?) bubbles in my attachment tapes in this area that had to be seen to be believed. It took over 10 hours of finicky sanding to remove without damaging the canard, brake lines and fuselage to start over.
From Tom Gordy
My worktables are 38" high and 37" wide. Three tables are used. One is 8' long, and the others are 4' long. When placed end to end, only a one-foot extension is required to allow jigging of the wing and canard. The 4' tables could have been made longer, but workspace size limitations dictated the use of the extension. The tables are a bit too wide to comfortably lean over during some long layups, and a bit too narrow for easiest cutting of the 38" wide glass cloth. I suppose no compromise is ideal. I would suggest builders consider building a wall-mounted rack for your cloth rolls and enclosing it for protection from dust and other contaminants. Hinge the front of the rack at the bottom and attach legs to the top of the front panel (also hinged) so that when you open it, you have a convenient cutting board/table. You can even draw lines at a 45 degree angle at four inch intervals on this table to aid in the cutting of the many BID tapes required during construction. Be sure that the cutting surface is smooth so nothing snags the cloth as you are moving it around. Of course, if you have an understanding spouse and an extra room, cutting your cloth inside the house away from your working area is ideal.
CUTTING THE SPAR CAPS
Begin by reading page 3-11 again. I placed short (1") pieces of tape every 12 inches or so along the edges of the cut UNI. Put them on after you pull out the fiber bundles to mark your cut line and before you cut the small cross fibers. They will hold the UNI together and you will not have to fight the edge raveling problems the plans warn about when you do your layup or while the spar caps are in storage. Scotch brand tape seems to be too sticky for easy, quick removal as the plys are laid up. Thin (1/2" wide) masking tape should work better. Since you will be wearing gloves during the layup when you want to remove the tapes (you will be, won't you?), remember to make an easy to grab tab by folding one end of the tape in on itself (sticky side to sticky side). As you remove these tapes from the wet layup, be sure to hold the cloth in place or you will have to re-straighten the fiber bundles.
I have highlighted each action to be done as called out in the plans. To make sure no step got skipped, I have checked off each item as it was completed. Writing 'PAGE COMPLETE' and the date at the bottom of each finished page has given me a feeling of accomplishment and progress which is probably far out of proportion to the work done. I have made no attempt to keep track of hours spent as the results would surely prove embarrassing.
CANOPY GLASS LINES. This one from Jerry Evans, Glasair builder. Using multiple layers of masking tape (maybe easier with duct tape), lay out the line around the perimeter of the canopy where you want your glass layup joining the canopy to the fuselage to end. The taped lines must be thicker than the proposed layup as you will layup the glass tapes up to but not over the tapeline. This way, after cure, you can just lightly sand at the tape/glass joint to assure no glass overlaps the tape then pull off the tape and have a nice sharp joint line. This avoids the touchy procedure of trimming cured glass and possibly nicking or scratching the canopy where it could fail later. (I recently saw a Glasair where the builder routed a small step at the bottom edge of his canopy then laid up glass into and flush with the step - presto!...a flush canopy joint line).
Also, you should always protect your canopy but avoid leaving masking tape ON the Plexiglas more than 7-10 days at a time or you'll risk surface damage or at least a difficult time removing adhesive. DON'T sand around the edges of your Plexiglas without a double layer of masking tape at least 3" wide in case you slip off your mark.
Use a good quality masking tape where you want good quality lines either in paint or glass. Only a good quality adhesive as on 3M tapes will stick tight and prevent paint or epoxy from bleeding under the edge.
From Ray Isherwood
Other tidbits picked up at Oshkosh
From the KR-2 forum, the recommendation was made not to use sloshing compound if you have plans to use auto fuel. The compound dissolves in alcohol, and alcohol is sometimes used as an octane booster, unbeknownst to the buyer.
Marv Getten, a Q-2 dealer from Maine, experienced a rupture of the plastic tubing supplying oil for the pressure gauge during climbout. He lost a quart of oil before he was able to get it back on the ground. He recommends adding a restrictor to prevent the oil from just pumping out. He also replaced the plastic tubing with copper tubing. Aluminum tubing would probably be a better choice.
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