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Me P-1112

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Me P-1112

Old 03-19-2023, 05:27 PM
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john491
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Default Me P-1112

I saw a thread not long ago on one of the forums ( and I can't find it anymore ) about a P 1101. Since this plane was the cause of my addiction to jet aircraft it caught my attention. I flew it and broke it a number of times and increased the fan size several times. I finally snapped the wing in two and had to retire the plane.
The same person who built the P 1101 also made a print for a ducted fan P 1112.

I built a plane based on those prints and was very satisfied with the flight characteristics. It finally succumbed to a flameout of the .45 ducted fan motor and totaled itself on meeting the ground.
The post motivated me to dig out the prints and try again, but this time I will power with a turbine. I hope to use an x-45 but may opt for a K70 depending on how heavy it ends up being.
The build has progressed as far as the bare sticks so far. It will probably go a lot slower for the time being as I am making a bunch of changes. I have seen at least four versions of this plane, which was never built. All I have to go on besides the print is a single three view. There was a single vertical tail version which had as many as three different inlet locations possible, and a v-tail version which also had as many as three different possible inlet locations. The wing also changed in there at least twice.




I will be using JP electric retracts and brakes as I have them on hand. I plan on mounting the turbine in the tail.
I plan on fully sheeting the plane, fiber glassing the surface and painting with over the counter rattle can paints.
John
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Old 03-23-2023, 06:47 AM
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Very nice.

A dutch builder is also making a P1112:

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Old 03-23-2023, 04:16 PM
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That is a beautiful build.
It is also the same version that I built for the .45 ducted fan . It flies very well and is relatively tame in handling. The reason I am not building it again is the inlet in the wing root. That caused me no end of engineering.headachs which are avoided by inlets in the side of the fuse. It is a midwing design which I have modified by lowering the wing on the fuse by about 9 %. Does anyone know if there was washout built into the wing?
John
Old 03-26-2023, 10:43 AM
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I've started the assembly of the parts I have cut out so far. In order to make sure everything is in alignment I have put together a jig to make sure the spars are parallel.

Unfortunately, the washout I was attempting to put into the wing worked out to be at 0 deg to the root instead of the 5% I was going for so I'm going to have to tear it down to the fuse formers and try again. To the good several things I overlooked in installing the ribs I can now correct.
John
Old 04-02-2023, 06:02 AM
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It occurred to me that a picture of what I am trying for would help.

The other version with a single tail is what the other gentleman is building with the inlets in the root.

For one thing the inlets in the root are a pain to do. Another is that the first example has a lower wing position which aids in spar placement.

Another example I was given a picture of.

As you can see this version uses an annular intake, which I was advised to avoid as it had required cheater holes in the ducted fan iteration. You can see them at the rear of the canopy.
Old 04-08-2023, 09:30 AM
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I was discussing the build with an engineer friend,

and he pointed out that by all rights a flying wing should have washout in it. I agreed and decided to aim for 5% . This proved to not be possible with the carbon spars holding the wings to 0 deg of washout. With carbon spars they are extremely rigid. So tore the build down to the fuse again removing all the ribs and sheeted port wing. I adjusted the jig for 5% and resheeted the top of both wings.
Old 04-08-2023, 10:05 AM
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I also added 1/16" plywood crutches forward and aft of the first rib on the side of the fuse to carry the nose gear and the turbine at the rear.


The idea of the crutches is so that the weight at both ends of the fuse were supported by more than the skin of the plane. In both locations the fuse shape goes from flat to cylindrical. They attach to the interior of rib 1 and butt up against the most extreme former in both directions. The ends of the crutches are about 6" past the end of rib 1 at both ends.
Old 04-14-2023, 02:19 PM
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I have the top of the wings sheeted, the space between ribs one and two which are cross grain to the wing sheeted top and bottom, and the bottom of the fuse planked. The planking strips are cut with a balsa stripper and are about 10mm on average. The width of the plank is freehand and depends on how tight a curve I am trying to go around. Fortunately, this airframe has 3 inches as the smallest cross-section. The hatch is framed up and the turbine mounts are installed.



My intention is to glass the exterior of the airframe before cutting out the wheel wells, hence the marking for the wheel openings. I hope this helps in keeping dust out and in keeping it easier to sand the finish.
I am working on the inlets now, as they need to be cut in next. I cut a wedge off a length of pipe insulation and will use that as a form to make the inlets.

John
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Old 04-17-2023, 05:06 PM
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It turns out the insulation idea as a form for the inlets did not work that great. They look good but are way too large.

I rooted through available material to make a smaller inlet mold and found a foam canopy from a Stinger 64.

I finished planking the fuselage after installing the inlets formed from the Stinger canopy.

Now to build and attach a fin and rudder, then sheet the bottom of the wings, then glass it all.
John
Old 04-24-2023, 03:37 PM
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I had a case of the clumsies and oversanded the fin hinge post while sanding another portion of the body. I corrected it with a little wood filler, then turned around and knocked the entire plane over and broke the top of the fin and shaping ribs when it hit the floor. That is all repaired now and will hopefully be covered so it won't be visible.

I am working on setting the rudder servo which I plan on fitting against the plywood sections visible in the picture. The servo is planned to mount up near the darker piece of plywood. The servo lead is to go through the hole visible at the base of the fin.
Rudder is hinged with large Robart hinge points. I plan on hinging the elevons with the same.
The plane is planned to be 47" long and 47" wingspan. It is currently 5.12 pounds.
I lowered the wing by 20mm from the prints, as I stated earlier, to give a more favorable location for the spar, and because the bottom of the fuse blends in with the wing better in this location.
The fin is proving to be more finicky than I anticipated, so it is taking a bit longer to get together than planned.
I also didn't sheet the bottom of the wing until I have finished the other construction so I don't damage it while working on it.
John
Old 04-27-2023, 05:59 AM
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This is a neat looking projekt! :-D
Old 04-27-2023, 10:52 AM
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Thanks.
It's been a lot of fun and keeps me out of trouble. It's always a challenge to build something nice and still keep the weight down yet strong enough to yank around the sky.
My rudder is proving to be more of a project than I anticipated as I can't seem to get the horn right, so I may have to make another. The existing one has taken seven or eight hours so far. I really enjoy watching the glue dry!
John
Old 04-27-2023, 12:24 PM
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It turns out I didn't mess up the rudder as much as I thought, so I won't have to build another. It is in acceptable condition and operates properly with about 35 degrees of deflection at full throw, which means I can dial it down easily in the radio.
Next I can sheet the bottom of the wings and apply the leading edges then glass everything.
John
Old 05-02-2023, 05:40 PM
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I finally finished the wood work and am now proceeding with smoothing the surface for glassing.

The nose is a lamination of 1" balsa circles I made with my hole saws, each a little smaller than the previous with the first two with hole cutouts to save weight, or conversely to add ballast if neccessary. This involves a lot of sanding.


Now comes the joy of sanding and fiberglassing. I know from experience this will take a couple of weeks and the end of which I will have to paint.
John
Old 05-03-2023, 04:07 PM
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I weighed the airframe just now and I am at 5.75#. Wing span 48" length 54". The retracts and turbine mount rails are installed.
Part of the prep I do for glassing the fuse is to apply a coat of sandable primer to highlight irregularities in the surface I haven't picked out by feel, then sand it all back off. I like to keep an eye on the weight as I go to keep me mindful not to get carried away with the painting. I'll then put a thin coat of primer under the fiberglass so I'm looking at an even color through the glass as I do the final primer step.
John

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Old 05-05-2023, 01:35 PM
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Always good to see a model built using traditional methods although I guess scratch building is
not really 'traditional' for turbine jets.

One product I use for filling balsa is drywall final filler, basically the last layer of filler used for
internal house walls. It's super easy to sand being much softer than balsa but quite dusty when
sanded, you will need a mask.

Keeping an eye on your progress!
Old 06-04-2023, 02:19 PM
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I have made some progress on the plane, and as I completed a few of the steps I remembered that I haven't seen a lot about fiberglassing posted on the threads. Possibly this is because this part of the forum is the wrong place to post this information, or as I believe , most people are using ARFs and kit planes so don't care.

As I do not have the money to afford these more expensive ways to go I thought I would share the solutions I use .

As you can see from the thread this is totally a scratch build, and I venture to guess that it will end up being stronger than most other choices.

The structure is supported ( in overkill ) by a carbon fiber spar that is continuous almost from tip to tip. The sheeting is 1/16" balsa over mostly balsa framing. The formers and ribs one and two are a light ply. I also added crutches of 1/16" light ply at the front and back to make it easier to transition from flat to round and to support the nose gear and rudder. After I was happy with the shape of the plane and it was sanded smooth I began the covering process.

First I primered the plane with a sandable white primer so that I could see with oblique light the areas that I didn't detect by feel. Once I had the plane smooth and a uniform color on the plane I put the cloth on. I apply the cloth by cutting a piece to the right size and apply a coat of 3M #77 spray glue to the surface I will be working on. ( I have tried several other glues and this one works best for me ) A really light coat. Like a 2 second waving application. Then stick the cloth to the surface and use a plastic squeegee ( a credit card ) to smooth it down and remove the air bubbles. This will make the application of the resin much easier and ensures the cloth doesn't wrinkle up on me as I apply the resin. This needs to be done quickly before the glue sets up. I find I have about 20 minutes to conplete this process before the glue dries up, but I usually wait till the next day to start the resin.
I use .5 oz cloth for covering.I was taught that the cloth is there to determine th amount of resin that will go on, not so much for strength. to give you an idea I have used a total of 5 oz of resin to coat the entire plane over a total of 24 square feet. It is spread extremely thin and sanded down smooth as resin is really heavy.

I mix the resin in very small batchs at a time. This means about 3 grams ( about 6 cc) of resin at a time. I have used a small flux brush to mix and transfer the resin to the surface, using the brush end on to push the resin into any corners. The flux brushes are cheap on Amazon, only about 5 cents each so it doesn't hurt when I have to throw them out at each mixing. Care needs to be taken doing this as bristles will break off if I am too vigerous and that messes up the finish. After the resin is transferred to the surface I spread it out using an old credit card. It takes me about half an hour to spread out 6 cc's of resin smoothly and thinly. Multiple thin coats are much more preferable to one thick coat. If the glass is not "filled" on the first try it can be done on a subsequent coat. It is MOST important to keep the coats THIN.

As an indication of what I am talking about as far as weight is concerned the weight of the plane with the wood work completed and the landing gear installed ;

5.75 # for the plane wood completed
5.98# with four cans of filling sandable white primer
6.12# fiberglass and painting on the bottom of the fuse
6.20# resin second coat and primered on bottom
6.75# all resin coats on, sandable primered top and bottom but not sanded.

It's a lot of sanding which is why it's taken a month. I still have to sand off this primer coat, and prep it for the final finish.

At the moment I am leaning to a light blue bottom and a bright red top. Our field faces South, so mostly I'll be flying it profile, but the red top will aid visibility on landing. The color choices may still change.
John












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