d boothe

My Feedback: (16)

What kind of glue is used on the foam wing sheeting ? I want to stay light as possible. Planning on substitutng the kit stuff for contest balsa and elimenating the trailing edge spar and making ailerons bigger.

wpmcnamara

My Feedback: (9)

I don't know what the original builder was using, but I used a fine layer of Gorilla Glue. Keep the sheeting well weighted while it dries. Dunno aboút weight, but when I tested it, I couldn't separate the sheeting from the foam without destroyÃ*ng both.

d boothe

My Feedback: (16)

Arent there two kinds of gorilla glue? ive read some post about it but its been a while.

Tony Hallo

You're looking for the brown colored stuff, the original. Keep the bottle sealed while using as the glue reacts with moisture in the air. It expands so use less than you think and work up if needed.

wpmcnamara

My Feedback: (9)

I use the stuff that dries white. Seems to behave much like the original, though I'm sure there are some differences. The reason? Cosmetic. Doesn't show up as much when I use to on visible foam.

Tony Hallo

I could be wrong but I thought the clear expands at 2X while the brown colored is higher.

wpmcnamara

My Feedback: (9)

Don't know about expansion, and neither the Gorilla Glue site, nor a quick Google search yielded any help, but the working time of the white is about half that of the brown.

d boothe

My Feedback: (16)

Ok so the white sounds like my speed, is that a Home Depot item?

wpmcnamara

My Feedback: (9)

Yep.

wpmcnamara

My Feedback: (9)

I have been very, very bad about keeping this thread updated. I have actually continued to work on the Laser as I have had time. Even worse, I didn't take pictures of everything so as I bring the thread up to date, some of it will just have to be text descriptions....


To make sure I got some cooling air through the canister tunnel, I put air scoops on the side of the fuselage. They were framed up with 1/2" stock and the cover was curved to match the curve of the cowl. I should note that over time the sheeting has lost its curve as it compressed so that it is pretty much straight now. I'm not sure whether I care enough to put formers in it to force it back to a curved state.

wpmcnamara

My Feedback: (9)

I only made a couple of other major structural change before I started covering. I replaced the back half of the door skin sides with light ply. I did this to allow for clean cuts for the rudder cables to pass through. I didn't replace all of it as it would have been a real PIA to do. The other thing I did was to make a fiberglass socket for the wing tube to pass through in the fuselage. The original cutouts in the fuselage sides were not the most round things in the world. The wing tube wasn't exactly making good contact with the fuse and I was pretty sure it would end up being loose in short order.

wpmcnamara

My Feedback: (9)

In some ways, covering was easier due to the larger size. It made it a bit easier to work with the Monocote. I opted to go for no wrinkles versus no seams so the top of the wing, though it had a solid color down it's length, was still done in strips that covered each wing bay -- just like the bottom.

wpmcnamara

My Feedback: (9)

Unfortunately I didn't take pictures while I was covering the fuselage. Once the fuselage was covered, it was time to check the balance and see just how bad it was. Turns out it wasn't horrible, but bad enough that the batteries would need to go somewhere other than the radio bay. It was nose heavy (expected) and needed about 3oz on the tail to balance. You can see my high tech variable weight in the first image. This was also the first time I got an actual measured weight. I had projected 25.5lb based on weighing the varies pieces and the estimated weight of the covering. Before everyone freaks about this being a 25lb plane, remember is has a DLE-111 in the nose and canister exhausts. It has a 96" wingspan compared to around 104-108" of a current 100cc airframe in the same weight range.

wpmcnamara

My Feedback: (9)

The mega image post!

Generally working from the tail forward... You can see the slots for the rudder cables. The cables are crossed internally to keep the slots as short as possible. The black brace wires are 2mm carbon fiber rods. Not only are they functional, they are absolutely required to keep the tail from vibrating off. Covering the tail was one of two very challenging areas on the fuselage due to the complex and compound curves where the turtle deck meets the vertical stab. The electrical setup has redundant flight batteries and a single ignition battery. The big white area in the fifth image is the cooling exit for the canister tunnel. The white is ceramic paint for heat resistance. The entire tunnel is coated. Eventually I intend to put a vented cover of some sort here. The two hatches behind the tunnel exit are for access to the battery compartment. All three batteries are located here to help significantly with balance. Moving forward we have the headers and front of the canisters. Again, the white is ceramic heat protective paint. You can also see the scoops for cooling the canister tunnel.

The electrical system is probably over engineered a bit. Running five ultra-torque digital servos can put a serious draw on the batteries. The flight packs have 14ga wire running from the packs to the power board. The ignition pack has 18ga. Power is routed to a SmartFly board. Servos are run off the high voltage input and the receiver is run on regulated 5V power though it doesn't have to be and I may move it over to the higher voltage input so I can better monitor the voltage levels via telemetry.

I put a full telemetry system on board. Right now I have GPS, temperature for each cylinder, and RPM. Assuming the plane flies well and stays intact, I'll likely add a couple more temp sensors -- one for the tunnel temp and one for the radio bay temp. I'm also going to try an figure out some way to measure the individual battery pack voltages. The LED mounted on the telemetry cross member is the ignition hot indicator. It comes from an opto ignition kill switch that you can't see in the pictures.

You can see the temp probe for the port cylinder. Its the little silver tube poking in between the cooling fins. It is actually bolted to the fin about half way up the cylinder head. I had to solder extension in the temp sensor and RPM sensor wires. Hitec, in their infinite wisdom, decided the RPM sensor leads only needed to be about 8" long. Doesn't work so well on a 33% airframe. I could have made do with the length of the temp sensor leads, but since I already had the soldering iron out... The ignition sensor magnet on the DLE-111 is capable of triggering the Hitec magnetic RPM sensor and there is plenty of room between the front case and the prop mount. The only problem is how to mount the sensor. Double sided tape and zip ties to the rescue. I am a bit worried about vibration of the wire though. I may try and get it secured to one of the bolts that connects the front and read of the crank case.

I have some washers inserted behind the motor mounts that I could remove and drop the gap between the spinner and cowl, but it actually doesn't look bad in person. There is enough of a gap that I shouldn't have to worry about the cowl hitting the spinner backplate due to vibration. The prop currently mounted in a 27x12 and it pulls like a horse. I have screw covers on the cowl mounting screws right now. They stick up pretty significantly, but they do a very nice job of protecting the cowl and hiding bright shiny screws. I'm going to wait until the cowl is painted to decide whether I keep them or try something else.

My helper.... She is a bit ticked because I cleaned up all her play toys (also known as covering scraps).

wpmcnamara

My Feedback: (9)

It flies!!!

Ok, more on that in a minute.

Last weekend I reached the point where it was time to take it outside and start it up without the cowl on it. This was actually rather uneventful other than the fact that the DLE-111 hadn't been started in about two years. The carb pump diaphragm had dried out and it didn't want to draw fuel. After pre-filling the tank to carb fuel line and a couple of rounds of squirting gas directly into the carb and a good bit of prop flipping, it came to life. It settled down to a good idle and would run great up till half throttle, at which point it would just quit. I ran out of daylight so I put it in the garage for the night. Thinking about it, I figured the high speed port was probably plugged up with old oil/fuel.

Whether that was the case or not, when I fired it up the next afternoon, all was good. Idle is about 1260 and fuel throttle is about 6490. Transition is good and smooth. Without the cowl on, both cylinders were running about 265F in 103F ambient. I did learn one thing though. The wing bolts are a royal pain to get in and out. I haven't come up with a good solution yet. The rear starboard one requires a socket with a universal joint and 12" extension to get in and out. It probably takes 10 minutes to get the wings on or off.

With everything at least running, it was time to do a final balance with all the gear on and try running it with the cowl on. Two things came out of it. First, it actually came out tail heavy. Not much, but tail heavy. 3oz of weight in the nose brought it into balance. If you fly a 5lb plane, that's a lot. A 25lb plane, not so much. Second -- cylinder temps. With the cowl on, the cylinders started to show the normal boxer twin variation. The starboard cylinder, which on a DLE-111 is the back cylinder, was running about 50 degrees warmer. I didn't let it run too long as the temps climbed with the hot cylinder hitting 350F before I shut it down. That was at about half throttle. The port cylinder was still about 50 deg cooler. I decided to go ahead and put air blockers in the cowl to direct the air right into the the cylinder cooling fins. I don't have pictures of that yet as I was working on it till late last night.

The air blockers plus 2oz of lead in the front of the cowl did the trick for balance.

wpmcnamara

My Feedback: (9)

Today was a field day. The weather wasn't the best for a maiden flight, winds @17 gusting to 25 and about 95 deg, but I needed to at least do a range check and taxi tests. Plus I figured I'd get to see how the new baffling was working.

Range check was fine, not that I had expected otherwise. The baffling was.... well.... baffling. It definitely changed the cooling. The starboard cylinder is now the cool one by 25-50 deg depending on the situation. However, heat is still an issue. Ground run ups of any length are a definite no-no. I actually overheated the engine while doing the range check. I couldn't do the check at high throttle as I didn't have someone to hold it in place so I was limited to about half throttle. But, even two minutes at half throttle was enough to put the port cylinder at about 397F (~202C). Luckily I popped back to the telemetry screen when I finished the range check and shut it down as soon as I saw the temps.

It still runs fine and smooth so I don't think any serious damage was done, but I do need to keep an eye on the temperatures when flying in the hot Texas sun. Flying temps hovered around 295-315F (146-157C). That was not running much above half throttle though as I was just doing check out and starting to trim it. I'd be much more comfortable about 25deg C lower, around 260F. I'm going to stare at the cowl a bit and see if I can figure out a good way to get it a bit more exit area. I might also look at putting some baffling behind the port cylinder to get better airflow. I probably won't do a whole lot right now though. This engine has about a half gallon run through it so it is still breaking in.

Trim wasn't horrible, though I do have some work to do. Elevator trim was about perfect -- about 4 clicks of up elevator. I set the the wing and horizontal stab at 0 deg so a bit of up was expected. Inverted took just a hair of down elevator. Rudder was spot on. Ailerons, not so much. I was actually afraid I was going to run out of trim. It needed something on the order of 15 clicks to the right, about 3/4 of the available aileron trim. I haven't had time to start the investigation as to why. The last time I checked the ailerons, both were straight as an arrow, as were the wings. Right now my theory is the the wing incidence is off a little bit between the two sides.

Stalls are pretty uneventful for an airplane that weighs a good 6lb more than normal. It gets mushy as it stalls and drops the nose. There was occasionally a little wing rock, but I had a little bit of a cross wind so its hard to say it that was due to stall behavior or wind gusts. It certainly didn't show signs of snapping or drastically dropping a wing. It does not, however, float. No surprise there though. When you stall, it drops fast. Similarly, you've got to keep power on when landing. While it does come in hot, as you would expect for a heavy plane, when you drop the engine to idle, the speed drops off fast. I could fly it to about 2-3ft off the runway, the drop to idle and let it settle in. It's not a floaty kite, but it shows signs of being a fun IMAC style plane.

I am going to have to look at potentially putting a bigger prop on it. Right now I have a 27-10 one it. It starts to rip a bit at a little over 3/4 throttle in level flight and in a shallow power on dive, RPMs were 7700-7800. Given the need for higher landing speeds, I might try a 27-12, though I certainly have clearance for a 28-10 -- as if I need more thrust.

wpmcnamara

My Feedback: (9)

As happens, Murphy likes to show his face from time to time. Not terribly long after the maiden flight, my club was holding an event for local youth so I figured I'd take the Laser and get a couple more flights on it, even though it isn't quite finished from a detail point of view. No such luck. The ignition decided to crap out. The starboard cylinder wasn't getting spark. That has been addressed with a new ignition module. However, since then the weather, even way down here in Texas, has turned less than pleasant for flying. So I've been working on.... PAINT!

I primed and painted everything. Primer was white Rustoleum primer for plastic. Spray, sand, spray sand. I painted with paint from Wings West RC. They have paint to match Monokote. Warning, it's not cheap. But, when done, it doesn't look like a cheap paint job either. Between base and top coat, I have about $160 in paint on the thing. I made a number of mistakes, some of which took some work to fix...



...some of which you can't see, and some of which I didn't bother to fix. Things I learned, or re-learned...

• Patience
• High humidity, especially when putting on clear is not your friend
• Neither is cold weather
• Dust free is a must
• Cat hair gets everywhere
• Just because your tape line looks well adhered doesn't mean it is
• Patience
• Meguiers is your friend
• Metallic paint is a royal PIA
• Patience

In the end, I'm happy with it. It's not near perfect, but then neither is the rest of the plane. I didn't start this build and there were a few decisions that I would have done different ha dI been doing it from the beginning. Painting is done. Tomorrow I will re-balance it and, if it isn't raining, check the new ignition. There is plenty left to do on this plane. Either I have an incidence issue or one of the wings/ailerons is warped. I will need to address that to get it to trim properly. But, from a building perspective, it's done.

wpmcnamara

My Feedback: (9)

I'm calling it done! It's now got six flights on it, four of which were in full paint. I put three flights on it today and it shows signs of being a monster. Top speed today, according to the GPS, was 111mph and I never put it in a power dive as I lost one of the tail brace wires and I didn't want to over stress the airframe hot-dogging. Engine is running smoothly now. 1200 RPM idle and about 7300 at full throttle in the air with a 27x12 Xoar laminated prop. Rips the prop in the upper 1/5th of the throttle band. Engine temps are ok. Port cylinder runs about 60F hotter than the starboard. It topped out at 273F flying today -- 59F ambient. I got several compliments about how nice it idled and numerous comments about how quite it is. Engine sips fuel. It has a 32oz tank and based on today's flights, 25 minutes at half throttle cruise and probably 20 minutes of vigorous aerobatics seems quite within reason. Certainly longer than I care to stand for a single flight.

It is heavy. The final dry weight is 26lb 7oz. That puts take off weight at just a hair under 28lb 7oz with a full tank of fuel. That's 9lb heavier than a light build of the kit and a good five pounds over the original expected weight. That said, the only side effect I have found so far is the expected high landing speed. It lands fast and needs a long runway. Not a problem at our field. In the air, it tracks well. I haven't done full stall testing on it, but so far it appears to just mush down the nose if you drop the speed and force it into a stall. It is not a floater, that is for sure. The glide slope is pretty steep at idle, again, somewhat expected. I certainly wouldn't describe it as a "pig", but then I wouldn't try and fly 3D with it either, though the engine is strong enough that you probably could.

I have a few minor things to do still. I need to make a new tail brace to replace the one I lost. One of the truss braces just behind the cockpit came unglued -- it gets a lot of stress getting bumped when I put in the rear wing bolts. I need to order a new spinner backplate. I wasn't paying attention when I drilled the new prop and its about 10deg off from where it need to be to match the backplate. Backplate is cheaper than the prop. Plus I need to expand the cuts in the spinner to accommodate the thicker prop. I'll probably hold off on both of those until I'm sure this is the prop I will stay with. A carbon fiber prop would look nice, but at twice the cost, I'm not sure it is worth it. The wing incidence still isn't quite right or I have a warped aileron. Not entirely sure which yet. Also the engine may need a bit of down and right thrust. More flights will be needed to determine for sure.

It's been a long, way longer than I planned, project but I'm happy with the outcome. I learned a lot. Some things I'd do different, some things I'd do the same but they would just come out better I think. The next project will be started from scratch, unlike this one that I inherited half built. I've got a 1/5th scale TopFilte P51 kit waiting in the box.

--wpm

sensei

Your Laser is actually 11 lbs. heavier than mine was empty, but who cares, as long as you are happy with it then that is all that matters. You finished it and you are flying, looks great and congrats.

Bob

wpmcnamara

My Feedback: (9)

Wow. Based on my current dry weight, dropping to a DLE-55 with the stock exhaust would save 3 1/2lbs. Dropping the redundant battery packs and seperate ignition pack, light weight switches, plus removing the Smartfly gear would save another pound. I could probably have knocked another half pound of wood out when I strengthed and redid around the radio bay. All total, that would be somewhere around 5lbs less weight which would put it in the 21 1/2lb range. I can't imagine getting another 6lbs out of it.

I still have the full plans and I have thought about getting a new kit laser cut from light weight wood for a future build. A DLE-60 twin would fit very well and be totally within the cowl, and it only weights 6 1/2 oz more than the DLE-61 single. Perhaps in the future... right now I have a 1/5 scale Mustang kit that is asking for attention.

sensei

Yup 15 lbs. 8ozs. with a DA 50cc on the nose is doable if you put your mind to it.



Bob

wpmcnamara

My Feedback: (9)

Sure is pretty. Was it from the original Lanier kit, and if so, how much of the wood did you end up replacing? I'm pretty sure I could get close if I had a new kit cut with the intent of a smaller engine. The firewall and and first former are pretty darn heavy and strong and could well be lightened as well as using good light ply instead of door skins. There is a lot of "over-builtness" in the original kit compared to any ARF you are going to get today.

sensei

Yes it was an original Lanier kit and I did not replace the wood, I thinned and lightened every stick, sheet or plank prior to gluing it in. I also went with a carbon fiber wing tube, main gear and Kavan wheels. I am very regimented about weight during any build.

Bob

Tony Hallo

The kit as made in the day when lasers and CNC were new and expensive technology, the use of such would have resulted in kit cost outside the norm that nobody would buy. That coupled with other popular beliefs resulted in heavier and more durable planes assuming you didn't crash! I can remember replacing the 1/2" firewall with two layers of 3/16" ply and was worried. Today larger engines are mounted on 1/4" plywood with lightening holes.
You build looks good and flies so be happy and enjoy. I have the original Wayne Urley plans of this plane than shows a geared .60 glow motor for power, 1981 vintage if memory serves correctly. I have the cowl, canopy and lading gear on the shelf waiting for a spot on the bench.

wpmcnamara

My Feedback: (9)

Oh, not worried, just amazed at sensei's dedication and skill. Mine does fly well, within the expectations of a heavy plane. Plus, I inherited it half built so I went with what I had. It is a pretty plane and I will be holding on to the plans, should it meet an untimely demise.