HobbyKing.com New Products Flash Sale
Reply
Thread Tools
This thread is privately moderated by kalmon, who may elect to delete unwanted replies.
Old Aug 25, 2013, 11:27 AM
Parkzone junkie
kalmon's Avatar
United States, MI, Grand Traverse
Joined Oct 2008
3,570 Posts
Mini-HowTo
UMX Habu Fiberglassing

I don't have a suitable landing area for my UMX edfs so I reinforce the bottoms to keep them from getting chewed up by the rough, weedy grass.

Before I got started I cut some foam from the battery tray to help move the CG back.


Now to the fiber-glassing:
First thing you need to do is prepare the bottom. There are tiny dots from the injection/stamping process. These little dots should be sanded down for a smooth surface. If you don't you'll get unsightly white circles where it lifts the fiberglass from the wing.

What I did was use some medium grit sandpaper and VERY LIGHTLY sand just the bumps. Don't press down or you'll scrape the paint around them. Here are the before and after images.


Now you cut some cloth so that it covers the rear fuse area up to where the fuse meets the Wing.

Use a natural soft bristle brush or small roller to apply some polycrylic to the glass.

Start from the center and work out. This will keep the glass tight and prevent wrinkles.
Do the same with the nose. On the nose I cut the glass down the middle of the opening. I then made a Y cut to the corners. This allowed me to fold the glass into the bay protecting the edges. You will need a VERY sharp knife to cut the glass without pulling it.


It is worth mentioning here that to make the trimming process easier you can use some painters tape to mask the areas you want the glass to stop at.

Finally the Wing. This is the hardest part. The Servos and covers are already in place so you'll have to work around them To make this easier I layed one piece on the wing that was a little larger than I needed. Also note that you need to leave enough to wrap the Leading Edge. I only put the polycrylic on the center part up to where the landing gear mounts. Let it dry an hour or so. Now it'll be pretty well stuck down but will also hold the cloth where it needs to be. Now you can trim around the the servos, landing gear and horns. Once those are trimmed out finish applying the polycrylic to the bottom.


Let it dry a couple hours then go to the top. I used tape so that I'd get a smooth line where the glass stopped here. I used green "Frog Tape" painters tape. DON'T STICK IT DOWN HARD! All you need is the first 2-3mm of the tape stuck down. Anyways wrap the leading edge pulling gently. Apply the polycrylic to the glass up onto the tape as well. make sure it is smooth and not wrinkled.


Let it dry a couple hours and then lightly sand with a fine grit sandpaper, 200 works great. The idea is to only knock off any high spots and to rough up the previous layer of polycrylic so that the next will stick well.
Now cut along any tape lines and remove the tape. Take care to not cut deeply as you don't want to cut into the foam just enough to cut the glass.

After this remove the tape. You should have a nice straight line.

Now apply another layer of polycrylic to the entire fiberglassed surface making sure to go slightly over the edges of those tape lines. This will give you a smooth transition.

Let it dry a few hours and you should be done.

Here is how mine came out:


-Brian
kalmon is offline Find More Posts by kalmon
Last edited by kalmon; Jun 26, 2014 at 08:03 AM.
Reply With Quote
Sign up now
to remove ads between posts
Old Aug 25, 2013, 11:59 AM
I just want to go fly!
walter3rd's Avatar
United States, MD, Towson
Joined Aug 2012
2,375 Posts
flight 20 in the books. still glitch free... knocks loudly on wood!!!!!!
walter3rd is offline Find More Posts by walter3rd
Reply With Quote
Old Aug 25, 2013, 12:00 PM
Parkzone junkie
kalmon's Avatar
United States, MI, Grand Traverse
Joined Oct 2008
3,570 Posts
Quote:
Originally Posted by walter3rd View Post
flight 20 in the books. still glitch free... knocks loudly on wood!!!!!!
pretty sure you wanted that on the full thread right?
kalmon is offline Find More Posts by kalmon
Reply With Quote
Old Aug 25, 2013, 02:30 PM
Registered User
WhalleyB0Y's Avatar
Canada, BC, Surrey
Joined Jul 2011
893 Posts
Hi Kalmon, did you weight the Habu before and after the process? I would really like to know how much weight was added and how it effects the flight performance. Looks really nice what you have done. Surely it will endure those rough fields well. Nice work!
WhalleyB0Y is offline Find More Posts by WhalleyB0Y
Reply With Quote
Old Aug 25, 2013, 05:17 PM
Parkzone junkie
kalmon's Avatar
United States, MI, Grand Traverse
Joined Oct 2008
3,570 Posts
Quote:
Originally Posted by WhalleyB0Y View Post
Hi Kalmon, did you weight the Habu before and after the process? I would really like to know how much weight was added and how it effects the flight performance. Looks really nice what you have done. Surely it will endure those rough fields well. Nice work!
I don't have a scale that precise. Given the weight of the actual glass and the fact that the level of polycrylic in the can appears unchanged I'd assume about 2g weight. The good news is that the majority of the glass is behind the CG so any added weight however small would help the nose heavy from factory problem. Polycrylic is wonderful stuff as being water based the water evaporates out as it drys and it adds very little weight

-Brian
kalmon is offline Find More Posts by kalmon
Reply With Quote
Old Aug 26, 2013, 01:13 PM
Romans 8:34-39
bhoov128's Avatar
United States, FL, Davenport
Joined May 2012
8,523 Posts
Great write-up, Brian. It's perfect for protection. One thing I might add is that sometimes when working in small detail areas it can be helpful to brush a light coat of the polycrylic or polyurethane directly onto the foam prior to putting the glass down. The glass will stick to the wet foam better and you'll have less finger-positioning to do than when you're trying to brush straight through the glass onto the foam.

This is a method I've used on a few scratchbuilds. Another thing worth noting is not only does it make a hard shell-like surface perfect for protecting the plane from scratches and dings, but it also adds a LOT of structural strength if you glass an entire wing this way. You'll be surprised how much stiffer wings are with just one layer of .5oz/sq in cloth and a couple coats of sanded water-based polycrylic or water-based polyurethane.

I built a plane with a 32" wingspan and prior to glassing the wings this way, if I held the plane by one wingtip the wing would flex nearly 3" down at the root. Afterwards, it flexes maybe 1/4". I also did a beautiful cartwheel across the grass with said plane just yesterday and nary a dent on the wings.

Thanks again for the how-to Brian.

Ben
bhoov128 is online now Find More Posts by bhoov128
RCG Plus Member
Latest blog entry: Snice Slick
Reply With Quote
Old Aug 26, 2013, 01:59 PM
Parkzone junkie
kalmon's Avatar
United States, MI, Grand Traverse
Joined Oct 2008
3,570 Posts
Quote:
Originally Posted by bhoov128 View Post
Great write-up, Brian. It's perfect for protection. One thing I might add is that sometimes when working in small detail areas it can be helpful to brush a light coat of the polycrylic or polyurethane directly onto the foam prior to putting the glass down. The glass will stick to the wet foam better and you'll have less finger-positioning to do than when you're trying to brush straight through the glass onto the foam.

This is a method I've used on a few scratchbuilds. Another thing worth noting is not only does it make a hard shell-like surface perfect for protecting the plane from scratches and dings, but it also adds a LOT of structural strength if you glass an entire wing this way. You'll be surprised how much stiffer wings are with just one layer of .5oz/sq in cloth and a couple coats of sanded water-based polycrylic or water-based polyurethane.

I built a plane with a 32" wingspan and prior to glassing the wings this way, if I held the plane by one wingtip the wing would flex nearly 3" down at the root. Afterwards, it flexes maybe 1/4". I also did a beautiful cartwheel across the grass with said plane just yesterday and nary a dent on the wings.

Thanks again for the how-to Brian.

Ben
Yes I noticed the strength addition on my full size Habu. Wings are rock solid in high G turns, a nice added benefit!

-Brian
kalmon is offline Find More Posts by kalmon
Reply With Quote
Old Aug 26, 2013, 08:44 PM
Happy Habu Hustler
Joined May 2012
1,093 Posts
Quote:
Originally Posted by kalmon View Post
I don't have a scale that precise.
I have three AWS 1kg digital scales. I like the price, and I can use these for park flyers.

There is also a 200g version.

If you buy just one to get the total weight, I can tell you that the box stock weight without battery is 61.5g.

Thank you for turning us on to this stuff. I probably won't glass the whole bottom as I won't belly land (I hope), but I may do the tail cone area, wing leading edges and battery compartment area.

I see you specified Frog Tape. Have you tried 3M blue painter's tape?
kevinrc is offline Find More Posts by kevinrc
Reply With Quote
Old Aug 27, 2013, 04:07 PM
Parkzone junkie
kalmon's Avatar
United States, MI, Grand Traverse
Joined Oct 2008
3,570 Posts
Quote:
Originally Posted by kevinrc View Post
I have three AWS 1kg digital scales. I like the price, and I can use these for park flyers.

There is also a 200g version.

If you buy just one to get the total weight, I can tell you that the box stock weight without battery is 61.5g.

Thank you for turning us on to this stuff. I probably won't glass the whole bottom as I won't belly land (I hope), but I may do the tail cone area, wing leading edges and battery compartment area.

I see you specified Frog Tape. Have you tried 3M blue painter's tape?
I'll look into getting a scale. Probably will be a month or two as I just dropped $500 on a frame repair on my truck!

any painters tape would work. I just had a bunch of left over frog tape from painting a couple rooms in my house. The frog tape is nice in that the adhesive is liquid activated and it doesn't stick as hard to the foam. Better chance of not removing foam bits/stickers/paint.

-Brian
kalmon is offline Find More Posts by kalmon
Reply With Quote
Old Aug 27, 2013, 08:01 PM
Happy Habu Hustler
Joined May 2012
1,093 Posts
Thank you.

One more question. I know you've stated this somewhere, but it would be nice here: what kind and weight fiberglass do you use? Where do you get it?

(OK, that was two questions. )
kevinrc is offline Find More Posts by kevinrc
Reply With Quote
Old Aug 28, 2013, 08:00 AM
Parkzone junkie
kalmon's Avatar
United States, MI, Grand Traverse
Joined Oct 2008
3,570 Posts
Quote:
Originally Posted by kevinrc View Post
Thank you.

One more question. I know you've stated this somewhere, but it would be nice here: what kind and weight fiberglass do you use? Where do you get it?

(OK, that was two questions. )
I used (1/2oz) 0.5oz fiberglass cloth. I picked it up from my LHS. I thew away the cardboard piece that came with it long ago, so I don't remember the brand.

Probably something out of the Tower catalog like this.

-Brian
kalmon is offline Find More Posts by kalmon
Last edited by kalmon; Oct 27, 2013 at 09:27 PM. Reason: Clarified the glass type
Reply With Quote
Old Oct 27, 2013, 08:06 PM
Happy Habu Hustler
Joined May 2012
1,093 Posts
Can you weigh your airplane, please, and throw the landing gear on top?
kevinrc is offline Find More Posts by kevinrc
Reply With Quote
Old Oct 27, 2013, 08:36 PM
Parkzone junkie
kalmon's Avatar
United States, MI, Grand Traverse
Joined Oct 2008
3,570 Posts
Quote:
Originally Posted by kevinrc View Post
Can you weigh your airplane, please, and throw the landing gear on top?
If I had a gram scale I would. Unfortunately I don't have one yet. Life as been really rough on my family lately financially. In the last two months I've had a $600 suspension repair on my Wife's Jeep, a $500 suspension/frame repair on my truck, and most recently a $2000 ACL surgery! I know those scales don't cost much but right now every buck is spoken for. In a few months I'll hopefully get one and I'll update this with the weight. I do know that Polycrylic being water based most of the water evaporates as it dries so it doesn't add much weight. Also with the majority of the plane being behind the CG any weight will improve the stock nose heaviness the plane had.

-Brian
kalmon is offline Find More Posts by kalmon
Last edited by kalmon; Oct 27, 2013 at 09:07 PM.
Reply With Quote
Old Oct 30, 2013, 12:07 PM
Parkzone junkie
kalmon's Avatar
United States, MI, Grand Traverse
Joined Oct 2008
3,570 Posts
I'd like to thanks kevinrc for the scale.! Thank you very much, you rock!

Here is the weight: with the gear on top. 64.8g Without a battery

Of note I did add a battery door using a dubro micro pin hinge and 4 very small N42 magnets. I'll weight these and add the weights. I also removed a tiny bit of foam from the rear of the tray area to allow a further aft battery placement.

Edit1:The magnets and hinge weight about 0.6g I have no way to weigh the vacuum formed plastic cover. I'd guess about 0.3 grams

-Brian

edit: pay no attention to the paper on the table... My wife works at a doctors office and sometimes brings work home with her.
kalmon is offline Find More Posts by kalmon
Last edited by kalmon; Oct 30, 2013 at 12:20 PM. Reason: just realized what the paper on that desk said... lol
Reply With Quote
Old Oct 30, 2013, 05:05 PM
Happy Habu Hustler
Joined May 2012
1,093 Posts
You're welcome!

Your weight after glassing and battery door was 64.8g.

My weight stock was 61.5; yours is 3.3g heavier than mine.

Your magnets and hinge weigh 0.6, now 2.7g are unaccounted for.

I suspect your guess on the door weight is pretty close, so now we're down to 2.4g for the glass, on an airframe that started approx. 61.5g.

Sounds like glassing added ~4% to the weight.

Thank you for data; I'm sure you'll find other ways to use the scale.

Kevin
kevinrc is offline Find More Posts by kevinrc
Reply With Quote
Reply

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
New Product UMX Habu with AS3X (14.6" wingspan) DominicM Micro EDF Jets and Power Systems 1759 Sep 23, 2014 02:15 PM
Discussion UMX Habu with AS3X (14.6" wingspan) bruff Micro EDF Jets and Power Systems 12 Jul 18, 2013 05:44 PM
Question Repair Surface Damage Habu 32 Nose, Fiberglass gva1956 Crash Discussion 1 Jun 26, 2013 12:43 PM
Sold Fiberglass E-Flite Habu 32 D caino Aircraft - Electric - Airplanes (FS/W) 1 Jan 07, 2013 04:59 PM
Sold Fiberglass E-Flite Habu 32 D caino Aircraft - Electric - Jets (FS/W) 1 Jan 07, 2013 03:40 PM