Topic: The next project. Aerobatic plane this time (Read 6415 times)

PhilStubbs · « **on:** January 24, 2013, 03:42:38 PM »

So, this is a fairly simple project, but its more fun for me than the parachute deal. I'm hoping we get something big in soon so I can show something that actually is cool.

Anyway. Anyone familiar with the Extra 300? We are a dealer/service center for them.

Every now and then we get an owner that wants to split the top cover of the fuselage at the vary back corner of the canopy. It's rare, but I'm doing this one now.

Here is the actual cover. The pic is upside down to try to show the part better. If we flip it back over today, I'll replace this pic.

And here is where it will be cut(interior paint has been stripped out, getting something new)

Hopefully this all makes sense. I have to make a flange inside first, then cut the cover in half. Here I sanded the area for the flange to bond

Hopefully this shows up better on a computer than my phone. I put packing tape where the flange will be, but only in the area I don't want it to stick and also put a little mold release wax on it. This will make much more sense when you see the finished product.

Then I trace out the shape of the flange onto this vacuum bagging plastic. The orientation of the layers is to aid in strength. Having the weave change direction for each layer makes it stronger.

Next I put resin on the plastic just a little bigger than the shape.

Once they are all wet with resin, I lay the carbon fiber on them and put another layer of bagging plastic on top of that.

Then just cut along the sharpie lines with scissors, peal off one side of the plastic and stick it in place. This is the first layer lightly stuck in. Once its sorta there, you can peel the last layer of plastic off and lay the cloth into the part with a paint brush. The plastic keeps the shape while you cut it and handle it. Without the plastic it would just stretch and stick to everything making a huge mess.

Here it is. Both sides done, 4 layers on each one with each ply alternating by 45Â°. Half of the flange lays on the sanded area to bond and the other half on the packing tape.

That's where it ends today. It will cure overnight, tomorrow I'll trim the excess off the edges and make the cut to split the cover in half.

Passenger · « **Reply #1 on:** January 24, 2013, 03:47:45 PM »

I'm kinda curious what this stuff gets billed out at? I would think there is a liability in doing these types of repairs and modifications?

PhilStubbs · « **Reply #2 on:** January 24, 2013, 04:00:28 PM »

There is somewhat. My name isn't in the log book so it actually isn't my ass on the line. This job is about $3k

Passenger · « **Reply #3 on:** January 24, 2013, 04:02:48 PM »

Quote from: PhilStubbs on January 24, 2013, 04:00:28 PM

There is somewhat. My name isn't in the log book so it actually isn't my ass on the line. This job is about $3k

Sounds cheap to me, all things considered. I would have figured liability insurance would really drive prices up there.

PhilStubbs · « **Reply #4 on:** January 24, 2013, 04:27:09 PM »

One thing that helps is this plane is experimental. I'm sure I don't have to explain that to you with what I remember you posting about your plane interests.

We charge $85hr which works great for the mechanic end, but it doesn't always work for us doing paint and composite work. Sometimes they drop the labor rate, sometimes they bill the customer more.

On the other end, we used to do a/c installs that took 3 people 10 hour days to complete and they charged $45k.

dvst8r · « **Reply #5 on:** January 24, 2013, 04:52:58 PM »

Quote from: PhilStubbs on January 24, 2013, 04:27:09 PM

...We charge $85hr...

On the other end, we used to do a/c installs that took 3 people 10 hour days to complete and they charged $45k.

The first one seems crazy, that is what I charge and all you get is me in a truck on the internet. Yes I realize the oil patch has completely skewed my reality.

The second seems more of what I was expecting, seeings how it costs like $20k to just fuel up a business jet.

Passenger · « **Reply #6 on:** January 24, 2013, 04:54:16 PM »

Quote from: PhilStubbs on January 24, 2013, 04:27:09 PM

One thing that helps is this plane is experimental. I'm sure I don't have to explain that to you with what I remember you posting about your plane interests.

We charge $85hr which works great for the mechanic end, but it doesn't always work for us doing paint and composite work. Sometimes they drop the labor rate, sometimes they bill the customer more.

On the other end, we used to do a/c installs that took 3 people 10 hour days to complete and they charged $45k.

Yeah the $500/hr for the AC install is more along the lines of what I was thinking.

PhilStubbs · « **Reply #7 on:** January 24, 2013, 04:55:58 PM »

That's including parts, but its around 70% labor.

malichite · « **Reply #8 on:** January 25, 2013, 11:09:46 AM »

I assume there is no STC for this for the non experemental extras.

Pretty slick deal though. Should be pretty low risk considering the skins are not structrual. Have a few friends with extras, one friend with a giles 220, one with an edge and one with a zlin. Fun airplanes to work on and usually pretty cool people.

PhilStubbs · « **Reply #9 on:** January 25, 2013, 12:38:17 PM »

I'm not sure if there is an stc for the certified planes. We have an FAA certified inspector on staff, we could easily get a field approval. It's so rare we do this its not worth the stc effort. I think the last one was 5 years ago.

So, here is where I started today. All cured and ready to make the divorce.

Trimmed off all the excess

Used a straight edge to mark a screw hole to still connect the 2 halves once its cut

Small screw hole for now. I drill now so it has no choice but to line up after its cut.

High tech shit right here. Hacksaw blade with tape on it. Lol. It's great cause you have lots of control and its thin. The blade is creating my panel gap when this is all done.

All cut. The flange is still rough.

All trimmed up and look'n purdy

Some other stuff came up so I can't wrap this up today, but Monday it will get a nut plate riveted to each flange so the 2 halves can get screwed back together.

mandrel-bends · « **Reply #10 on:** January 26, 2013, 04:05:35 PM »

Very cool, but incredibly scarey liability. You guys are cheap too, the local air repair place charges more then $200/hr to touch anything.

I'm always more freaked out by airplanes when I leave that place then when I go in. Balsa wood laminated helicopters and stuff. Insane.

PhilStubbs · « **Reply #11 on:** January 26, 2013, 04:38:08 PM »

Yea, lol. The spar in the wings of these is foam wrapped in carbon and all of the ribs are wood. We have to replace them all the time when people scrape wing tips on the ground and stuff.

runsfromdacops · « **Reply #12 on:** January 31, 2013, 02:55:41 AM »

gota love the extra 300L one of my all time favorit planes

plz post more of the plane work you do, it vary interesting and not something we get to see often

PhilStubbs · « **Reply #13 on:** January 31, 2013, 09:08:10 AM »

Right now its just a bunch of boring cracks and exhaust burnt foam core. I'll keep an eye out for interesting things though

92CXyD · « **Reply #14 on:** January 31, 2013, 09:39:02 AM »

Quote from: runsfromdacops on January 31, 2013, 02:55:41 AM

gota love the extra 300L one of my all time favorit planes

plz post more of the plane work you do, it vary interesting and not something we get to see often

W3rd

crxvtec91 · « **Reply #15 on:** January 31, 2013, 10:40:42 AM »

Interesting stuff, I thought you would have to vacuum the carbon?

PhilStubbs · « **Reply #16 on:** January 31, 2013, 11:02:03 AM »

Depends on what you are doing. Anything structural gets vacuum bagged. You can work it just like fiberglass for things that don't need a lot of strength and its still stronger than fiberglass without bagging. I'll look in our shop computer and see if I can find pics of good stuff.

runsfromdacops · « **Reply #17 on:** February 01, 2013, 12:11:45 AM »

so what is the reason that the customer wanted to have the piece removable ??

PhilStubbs · « **Reply #18 on:** February 01, 2013, 08:33:12 AM »

There is an autopilot servo and some avionics stuff under it. It takes at 4 people to get the complete cover off. 1 person can take off the back half. It's not heavy as one piece(30-40lbs) but the wing is in the way and you have to work it around the canopy hinges and things

runsfromdacops · « **Reply #19 on:** February 01, 2013, 07:09:00 PM »

this maes alot more sens now

NoPistons! · « **Reply #20 on:** February 03, 2013, 03:27:15 PM »

Quote from: PhilStubbs on January 31, 2013, 11:02:03 AM

Depends on what you are doing. Anything structural gets vacuum bagged. You can work it just like fiberglass for things that don't need a lot of strength and its still stronger than fiberglass without bagging.

This and +1 for the hacksaw blade.

So the vac bag is just like a flexible backing that allows the piece to be worked? It's not actually vac formed?

PhilStubbs · « **Reply #21 on:** February 03, 2013, 03:36:00 PM »

A vacuum bag is basically Saran Wrap taped down with the repair or part under it. A vacuum pump is connected to it and it sucks down to act as a clamp. It also pulls excess resin out. Most people put too much resin in a composite repair, there is no strength in resin alone. You want a 60/40 cloth to resin ratio for optimum strength. When bagging you can put way too much resin and then use the suction to pull the extra out. Next time I do a vacuumed repair I'll take pics of the whole process with all of the layers and descriptions of what's going on. Maybe even try to get a video of setting the amount of suction. It's usually about 10inhg, but sometimes more.

NoPistons! · « **Reply #22 on:** February 03, 2013, 04:08:43 PM »

Thanks for clearing that up. That sounds interesting in itself. Def beats the old school way of repairing stuff. No bubbles. No lifting/sagging parts. No messing around with like 4 or 5 different clamping arrangements to have pressure on a weird shaped piece.

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Author Topic: The next project. Aerobatic plane this time (Read 6415 times)