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Getting started with composite parts in Indoor

In Uncategorized on October 4, 2019 by nicholasandrewray

Getting started with composite parts in Indoor

By Mike Kirda

As I get asked this quite a bit, I thought I should just write up what it takes to get started making composites for indoor models.

Here is a list of supplies needed.

Vacuum pump – Gast pumps are often found on ebay rather cheaply. You can find inexpensive vacuum pumps at Harbor Freight as well. I used a FoodSaver in the beginning. It works. Use a food saver at first if you have one. If you decide you really want to do this, a used Gast pump is, I believe, a better option than the Harbor Freight ones. Your mileage may vary.

Acid brushes – Harbor Freight

Nitrile gloves – Harbor Freight

3.5-4 mil plastic sheet – Harbor Freight

Old credit cards, stiff plastic from mailers, etc. Use for spreading epoxy or evening it out on flat laminates. Composite stores also sell purpose-made spreaders.

Caulk gun – Home Depot/Lowes/Harbor Freight

Inexpensive caulk – Any local hardware store

popsicle/craft sticks. See your local dollar store or craft store.

1 oz medicine cups for mixing epoxy – CST/ACP should carry them.

Wax – Recommend Part-all #2. Any composites store.

Laminating Resin – I highly recommend MGS resin. Nothing I have tried wets out carbon as well as MGS. I would recommend getting both the 285 and 287 hardeners so you can vary the amount of time before the resin gels. Wicks carries this. Other composite stores do too.

Fiberglass – You can get away with just two sizes of fiberglass. You want 0.5oz cloth as it is just about exactly 0.001” thick when wetted out. 3.6 oz cloth is just about 0.006” wetted out. 0.75 oz cloth comes out thicker than 0.001”, so may end up sanding a lot of it away.

https://www.thayercraft.com/0.56-oz-104-volan.html

https://www.thayercraft.com/3.63-oz-1522.html

Sharp scissors can cut up to roughly 7 layers of 3.5oz cloth. Offset tin snips are a better choice though, especially on thicker laminates. JoAnn and local hardware stores.

Carbon – ACP/CST have lots available. IndoorFFSupply.com carries the hard to find Toray M60J in small spools. Mike Woodhouse carries light Russian Unidirectional cloth that can be a source of very light tow.

For a hot box, I use a simple temperature controller that turns on a lightbulb inside a plastic cooler. For very large laminates, I have used a carboard box with a bunch of blankets on top. Use of a computer fan inside the box or cooler would likely result in more even temperatures inside.

https://www.amazon.com/Inkbird-Max-1200W-Temperature-Controller-Greenhouse/dp/B01HXM5UAC/

Nice to have:

A cutting mat and rotary cutter for cutting fiberglass to size. Makes things a heck of a lot easier. JoAnn Fabrics. Like Bed Bath and Beyond, they ALWAYS have 20% off coupons.

A valve between your pump and the bag. This way, once you pull a vacuum you don’t need to keep running your pump. Put the vacuum gauge between the bag and the valve though.

An interlocking bag connector.  Most of the leaks seem to occur around the hose. This can eliminate that source of leaks. Composite stores.

Glass sheet – You can wax it and place laminates on top of it to get them perfectly flat. Just make sure the glass is really really clean and wax it and wax it and wax it again before you start.  Drive around alleys to find when folks throw our furniture and grab any glass panels you find.

Mylar sheet. This also needs to be cleaned and waxed several times. Should be at least 0.010” thick, with 0.014” maybe better. Useful to sandwich laminate/core/laminate, like carbon/balsa/carbon. Composite stores.

Nylon bagging material with easy-close clamps. With the bag connector above, you have a solution without caulk that potentially holds the seal better. Alternative is bagging tape, which is even better, but this makes the setup single-use. Composite stores.

Please note that nylon bagging material does not generally last more than one or two uses. However small leaks can be stopped with caulk.

Paper towels work really well for soaking up the small amounts of resin that we will generally use. Mostly I use a good quality paper towel like Bounty. Polyester felt is sold at the composites stores and it works really well for larger jobs. Some jobs might benefit from a perforated release film with the felt on top to really soak out the resin. It depends a lot upon the job size.

 

 

Part two: A few hints

Measuring out epoxy: depending on the specificity of the work, there are a couple of ways to measure it out.

  1. Visually via gradations on the 1 oz medicine cups. Works great for non-critical work.
  2. Disposable syringes (eBay)- You can get very precise volumes with syringes.
  3. Milligram scale: You can get very precise weights with a milligram scale.

Note that by weight and volume will have different mixing ratios!

Mixing epoxy:

Get a mixing stick and get to work. It takes a good several minutes. I do a minimum of three minutes, but five is better. You can whip it into a froth, the bubbles will come out quickly.

DO NOT THIN YOUR EPOXY with alcohol. It works better to heat it, but only if necessary. Heating it will decrease pot life/working time.

 

Do everything with a plastic sheet over your table top. When done, put waste in center, wrap it all up and toss it out. Much faster cleanup this way.

Always wear nitrile gloves. You do not want to develop an epoxy allergy.

Sanding should only be done outdoors or within the intake range of a HEPA filter. Protect your lungs.

Always wash up afterwards, hands up to elbows.

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Lakehurst Labor Day Report – 2019

In Uncategorized on September 7, 2019 by nicholasandrewray

Lakehurst Labor Day Report – 2019

Brett Sanborn

After a four-month delay, the East Coast Indoor Modelers (ECIM) regained base access and resumed flying in Hangar 1. The main tenant of the hangar decided to forestall our license and access when it came up for renewal in April. According ECIM club president Horace Hagen, there was a misunderstanding and the primary tenant believed we were flying large gas powered outdoor aircraft and was worried about damaging stored equipment. After much explanation and many meetings, Horace was able to obtain a new license for this year. Along with the new license, a few new rules were put into effect, but they were minor. Though a full list was provided by Horace, some highlights include that we are no longer allowed to close any doors that are open and now must park at the west end of the hangar. Being able to close the large door at the east end of the hangar would be nice, but overall it didn’t have a huge effect. Other than that, it was business as usual at Lakehurst. We did get a couple visits from the base police, but it was due to their interest in seeing the models rather than for monitoring our conduct. Nonetheless, we must be on our best behavior while flying to ensure future access.

Conditions over Labor Day weekend were good. Saturday was probably the best weather-wise, closely followed by Sunday. Temperatures inside the hangar were about 80 degrees and 40% humidity. On Sunday, we experienced some drift toward the west end of the hangar especially when models were up high. Though it may have been exacerbated by the open end-door, this pattern is normal. We had scattered thunderstorms on Monday. The air was still flyable in general, but we were dodging drips during flights. I had a flight that began stalling around unexpectedly, and indeed when it landed I found some large water droplets on the stab. Luckily none of the film is damaged by falling water droplets. The storms cleared up around 1 hour before sunset, so we were able to make a few final flights before it got dark.

The lack of availability due to the national helium shortage had an impact on our flying. The Party Fair in Toms River will no longer rent the club a helium tank. I called several places in New Jersey and Ohio and was told ‘no’ by all but one. Though this store was willing to rent a tank, they wanted to charge $650 for 300 cubic feet. We were forced to drive to the store and fill up a single balloon (for a whopping $20) and drive it back to the hangar. Steve Fujikawa and John Kagan filled their mylar balloons at the store which are advantageous in that they do not need to be topped off daily to be useable. The balloons lasted the entire weekend.

The contest was attended by Steve Brown, John Kagan, Andrew Welter and his dad Ron, Mike Coplan, Steve Fujikawa, Dave Campbell, and me. Andrew practiced and qualified for the Junior F1D team selection contest which will be held at Lakehurst over Columbus Day weekend.

 

 

Results

F1D

Brett Sanborn:  31:24 + 31:08 = 62:32

Andrew Welter: 21:25 + 19:15 = 40:40

Steve Brown: 26:08

F1L

John Kagan: 20:13

Mike Coplan: 20:00

A6

Mike Coplan: 6:25

LPP

Mike Coplan: 7:06

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Akihiro Danjo’s VP Mechanism for F1M and F1D

In Uncategorized on August 19, 2019 by nicholasandrewray

Akihiro Danjo’s VP Mechanism for F1M and F1D

VPF1MF1D copy1

VPF1MF1D copy2

Click here to download a PDF of the plan.

 

Construction Photo Essay:

Drive arms and stop arm are made from a single piece of 0.011” music wire for F1M and .008” for F1D.

 

The shaft is inserted though the arms. The shaft diameter is 0.013” to .015” for F1M and .012” for F1D.

 

Tape the arms and a shaft on this jig to set 45 and 90 angles.

 

I use Stay Brite though any solder will be OK.

 

The main body is 2mm thick #10-12 balsa, 3mm tapered to 2mm for F1M. Lighter wood and 2x2mm for F1D. I use total eight figure ‘8’ hinges for F1M and four figure ‘8’ hinges for F1D.

 

I use Kevlar thread for hinges. Kevlar thread is untwisted to get suitable strands.

 

Kinoshita-san uses silk thread for F1D, but I use Kevlar for F1D too.

 

A socket filler is used for F1M only and it is 2.0mm dia by 8mm long balsa.

 

Shaft bearing is cut from stainless steel tube. HTX-23-6TW (.025”od x .017”id) for F1M.

 

 

The Drive pin is 0.011” wire for F1M and .008” wire for F1D.
Drive pin for F1M is short and straight. It is inserted (pushed) into the socket tube and the filler and then CyA glued.
Drive pin for F1D is ‘?’shape and is glued to outside of the socket tube (therefore there is no filler for F1D).

 

Spring supports are 2x2mm #10 balsa for F1M and a little lighter balsa for F1D.
This is an extra short spring, so the supports are not a triangle but just a small block.

 

Stopper screws are nylon #0-80 x1/8” for F1M and 00-90 for F1D.
Screw holders are #10-12 balsa. I don’t use a tap for threading. Just only screw a nylon screw into the prepared hole. Sometimes very thin glue is used to harden the thread.

 

Adjust the height of the screw holders and glue them on the main body.

 

If you need softer, thinner, spring for F1D, it will be better to join thinner, i.e .010”, wire together than using thinner than .012” wire for the shaft.

 

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2019 Otto Hints Memorial

In Uncategorized on July 16, 2019 by nicholasandrewray

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Evan Guyett’s 2019 US Team Selection Model

In Uncategorized on July 16, 2019 by nicholasandrewray

Evan Guyett’s 2019 US Team Selection Model

F1DOrange2019TeamSelection-Model copy 2F1DOrange2019TeamSelection copy

Click here to download a PDF of the plan.

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Ivan Treger’s 2019 European Championship Model

In Uncategorized on July 16, 2019 by nicholasandrewray

Ivan Treger’s 2019 European Championship Model

F1D ME 2019 001F1D ME 2019 material 001

Click here to download a PDF of the plan.

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2019 European Championships Results

In Uncategorized on July 5, 2019 by nicholasandrewray

2019 European Championships Results

ME_F1D_2019_resultsFINtitl copy 1ME_F1D_2019_resultsFINtitl copy 2ME_F1D_2019_resultsFINtitl copy 3ME_F1D_2019_resultsFINtitl copy 4

 

Click here to download a PDF of the results.