| Author | Message | ||
     Anonymous |
The following was posted on the KIS mailing list. Tom Hello Geoff and others, I'd like to offer some observations from a novice on this subject. I have rolled on 7 quarts to date -- one of the original Smooth Prime and six of the UV Smooth Prime. I have the highest regard for Jon Goldenbaum and the Poly Fiber company and their products, but the real test of a product is how it performs and is used in the field by us amateurs so I'd like to start some dialogue. If you are going to Osh Kosh I highly recommend that you attend a seminar given by Jon on finishing composite aircraft. Get one of his free finishing manuals if the latest one discussing UV Smooth Prime is available. I plan to email this posting to Jon also so that we can benefit from his feedback. My application was to my wings, my ailerons, my flaps, and my elevator laid out flat in a garage with temps above 90 deg F.My observations in no particular order of importance: 1) This is high quality, high priced stuff with lots of titanium dioxide ($$$), talc, and mica solids incorporated. 2) This stuff really sticks. Plan your approach so that you have absolutely the minimum of clean up to do -- preferably just the brush and roller. Use disposable paper containers where possible. 3) Buy it by the gallon -- it is significantly more expensive by the quart. 4) It is just too thick right out of the can to roll on properly for the first couple of coats at least. I know that the interim instructions that come with it say to not thin it.This may be sort of a hold over from the initial non UV Smooth Prime instructions. But this stuff has more solids and you still need to start out at least with very thin coats. I believe the only way that you can get those initial coats thin enough is to thin the paint -- trying to smash it around right out of the can with a roller just won't do it. And those initial coats need to be thin enough to start to flow down into the pin holes -- I was still looking at pin holes after 5 coats right out of the can.Then I started to thin (see below) and the pin holes quickly filled. 5) Batch sizes. I found that cross linking one pint at a time was managable, but a lot of work / time to spread. That takes 8 cc of cross linker. I recommend that you start out with 1/2 pint batch (that takes 4 cc of cross linker) and see how it goes. Rinse out the syringe with warm water right after you use it if you want to use it again. 6) If your roller and brush are not acually in use they should be sitting in a container of water to keep them from drying out. 7) Thinning technique. Here is what eventually worked for me. I used a paint stirring stick cut in half to stir for 3 minutes. I carried the mixed batch up to the garage in a pint cardboard container for the 1/2 pint batches and a quart container for the 1 pint batches. I would use the stirring stick to drizzle around a quantity of paint out of the container into the limited area that I had mentally picked out to cover. Then I would take a 1 1/2 inch paint brush out of a nearby plastic container half filled with water and run a light strip of water the length of the roller. Then I'd proceed to load up the roller and spread around the paint that I had previously drizzled by rolling the roller around in that limited area. I know, I know, it sounds like a lot of mickey mouse at first, but you soon get very adept at drizzling out the amount of paint that you want and wetting the roller just right -- you are in control and you can fine tune your technique and quantities as you go along. Besides, see item 2) above. 8) Sanding. I had a break of a couple of weeks in the middle of this process while I waited for some more primer to arrive. So I decided to sand a bit. This stuff sands beautifully, generates copious amount of white dust very quickly. I would recommend some sort of vacuum assisted approach. Bumps and lumps are not a problem, they will sand away very readily and smoothly. What is a problem are pinholes and pits that remain after sanding the surrounding area as much as you feel you should. So the name of the game is not necessarily to get a smooth coat laid on, you are going to sand it regardless, but to get a coat laid on that will fill up those holes. I feel that 320 grit is what you want to sand with. I'm also struck a little by the dichotomy facing us. We are supposed to prime months in advance of final sanding and painting (see previous postings about fabric weave showing up) so this means we lay on 6 to 8 coats per Poly Fiber's instructions, wait several months, and then sand only to discover that we are about 3 to 4 coats shy in some depressed areas. So we are right back in the priming business. How many times do we go through this cycle? Is everybody comfortable with this? | ||
| Gary Markwardt |
I'm trying to dream up a paint scheme for my new Express N713GM & wonder if anyone has an Express line drawing I could use to sketch up ideas. I have a low tail series 2000. Also, any ideas/suggestions for schemes would be appreciated too. Thanks. | ||
| Bill Copeland |
Gary: I believe that the factory has a three view of the Series 90 that they used in an earlier ad brochure. I just looked for a copy that I might have, but was unable to turn it up. Hope that helps. How close are you to completion - or have I missed that event. Bill C | ||
| Gary Markwardt |
Bill: Thanks for the feedback. I did ask Larry Olson for a line drawing awhile back without success. I'll try again based on your info. Re: airplane status -- I am in the builder assist program & very close to flying. Tom Hutchinson & I started building the same week at Rochester (started the kit 7/13/99, hence N713GM). I elected to have Express do the finish work (#3 after Butler & Hoff); but, have been out to OLM frequently for 1-2 week sessions to do as much of the completion myself as possible. Engine is running & body work is being finished up now by Express. Should have an FAA insp. completed in May. Hope to fly home to MI this summer. | ||
| Phil & Margie Hodge (N410mp) |
I have the original Wheeler 3-view drawings of the cruciform tail, if you can't find a low tail version. I'm in the process of manually inputting the drawings into AutoCAD, and will be able to print copies for any builder that wants them. Be patient, though, I'm off for Sun-n-fun in the morning, and already behind at work for the rest of April. | ||
| Terry Sack (Terrair) |
If Tom will let you, why not post the drawings to the site? You will have to limit your cad drawing size, I'm sure. | ||
| Sven-Ake Eriksson (Sven) |
Hi everybody Question: Does anyone know approximately how much weight there will be added by priming and painting the control surfaces (elevators, rudder, ailerons and flaps)? Sven Eriksson | ||
| rob jordan |
I'm balancing my elevators and have a thought. I have too much weight in one elevator and I am a little light on the side with the trim tab. The elevators are finished with paint etc. My question is why would it matter if each elevator is balanced if the whole control was balanced. In other words once you bolt the elevators together they are one control surface. wouldn't balancing them as a whole work just as well. this would mean adding a couple ounces back to the lite one to balance my heavy side? any thoughts? From what I've read about flutter this is still meeting the goal. | ||
| Eric Holmberg (Erich) |
Hi Rob, Assuming that the connection between them is rigid enough, that should work. However, considering the fact that both elevator sections are weighted, I would think that the designers had a good reason to do it. You don't add lead to an airplane without a very good reason. Since I'm just a computer engineer, I'll defer to any of the aeronautical guys out there to give an analysis taking the torsional flexibility of the elevator assembly into account. I would be of the opinion NOT to skimp on one side. -Eric | ||
| Reinhard Metz |
If I understand flutter and balancing correctly (This is superficial - there's a lot more to it in the details), if you imagine a movement perpendicular to the hinge line (vertical in the case of the elevator), then that movement will not lead to any control surface deflection, if it is balanced, i.e. the moment in front of the hinge is equal to the moment behind the hinge. (Imagine this particullarly in a shock-input environment, such as turbulence.) If it is not balanced, then a deflection will occur due to the mass-moment difference. Given the right resonant properties of the control surface, and force input environment, such as determined by speed of the airflow, resonance can occur and be excited into an unbounded mode. In the case of your elevator, for the total moment balance to still "meet the goal", I think you need to take into account the stiffness of the whole assembly, and specifically the torque tube connecting the two halves of the elevator, as it would be an important element of one half of the elevator balancing the other half. To some extent, this is already the case within an elevator half, where the lead balance weight is in the corner, but you can readily imagine that the elevator half is stiff enough that any internal tortional resonant frequencies are well above any fundamental resonances. So, my guess is that the question is whether the tortional resonance through the connecting torque tube is above or below the fundamental frequencies of the overall elevator. I would definitely not rely on the total assembly to be stiff enough to act as a whole. It's easy to imagine the torque tube being a sufficient isolator to allow each elevator half to flutter independantly. Sorry, but I would balance each individually. I remember on my previously owned Bonanza the procedures were very clear about individual balance. Reinhard Metz |