Category Archives: Big EDF Jets
Here are the vital stats on the F-14 Tomcat:
|Constructed from plans designed by Matt Halton in the UK.|
|Blew the plans up to 123% original size so the plane could accept 90mm fans.|
|All balsa sheeted construction with tissue-dope covering.|
|Twin Schubeler DS-51-3PH 90mm fans. Obtained via ShredAir.|
|Twin Hacker B50-10XL brushless motors. Obtained from ICARE in Canada.|
|Twin Schultze 80bo speed controllers.|
|SpringAir 305 retracts|
|44 x Sanyo CP-1700 cells|
|NOT YET FLOWN! Almost complete!|
Here is the construction sequence for the Tomcat:
Here is the initial layout of the fuse formers. One of the other early Tomcat builders pulled the fuse parts into Autocad, and laser cut fuse parts. These fuse parts are now being sold by Jet Hangar Hobbies. Saved me lots of time in front of the scrollsaw.
I have the formers together now, and part of the bottom sheeting applied, plus my initial ductwork fitting. I am using stiff paper card for the ducts.
Here is my early fitting of the GX parts that form up the inlet ramps, and wing glove area.
Here is the glove rough sheeted, but not yet sanded. Notice the fuselage sheeting is starting to come together at this point too.
In order to bend ductwork out of heavy card, I made some duct forming tools out of some dowels and some of the duct punch-outs from the fuse formers.
I reinforced the ductwork in places where it still seemed weak with some strips of 3/4 oz./in. glass cloth and epoxy resin.
Most of the ductwork is in here, and I have some of the fuse sheeting complete. The duct transitions are held together with a bead of thick CA glue.
The motors and speed controllers showed up from ICARE. It took awhile to get them (about 2 months), but it was well worth the wait.
I have most of the bottom sheeted, and the nose wheel is test fitted into place.
Sheeting the bottom of the plane goes VERY slowly. I used 3/8″ strips of balsa, and planked the bottom with them. I used aliphatic resin to glue the strip into place, which has a slow (30 min) curing time. It’s slow going, but I end up with a much better, and sand-able finish than doing it using CA glues.
Took me well over a month of evening and weekend gluing to sheet the bottom of the plane. Here it is, starting to fill now and sand. I use lightweight wall putty to fill in the cracks and divots.
Whoops! Problem. The sheeting doesn’t line up right with the fuselage edge. Notice the lip. I had to break this joint loose, and re-glue it with a shim in place to hold it out so it would be flush with the 3/32″ balsa planking I was using.
Here I have started planking the turtle-deck area to get ready to work on the cockpit.
Working on the inlet ramps here, and completely sheeting the wing gloves. Lots more filling and sanding to be done. My arm is sore at this point.
Nose gear is now permanently mounted into the plane. I built up a mount out of spruce, plylite, and epoxied the gear mount down using carbon fiber laminate.
Main gear now mounted into the plane also using spruce mounts, reinforced with carbon fiber laminates.
Carving a nose out of pink foam. I cut a foam blank from the per-plan 2d pattern, and made a 3d foam blank. It took me 5 tries to get the blank the right shape. What a huge mess I made! Pink foam all over the garage.
After some initial shaping, I mounted the pink foam blank on the plane, and sanded to shape. A little bit of wall putty to fix the tip of the nose, and the transition, and then I was able to cover the nose with 1/2oz. glass cloth and resin. A little wet sanding later, and my nose is looking permanent. Here is a photo of the recently sanded nose, pre-glassing.
Starting to look like a Tomcat now!!!
Another eZoner, Admiral Red, worked up these beautiful wing templates using Compufoil and Autocad. He emailed me a DXF file, and I printed them out, and cut wings from the design. Here are my freshly cut ribs laid out on the printout, ready to construct a built-up wing.
Here are the wings, single-sided.
Time to make a REALLY strong set of wing spars. I was guessing the AUW of the plane would be over 12 pounds. I knew I needed them to be bulletproof. I laminated together pieces of maple, with lite-ply in an I-beam formation using 2 hour epoxy.
Here is a spar being test fitted into the wing.
More test fitting.
Wings are finished and ready to go!
Lets put them on the plane and see what she looks like!
Here is my initial cockpit decking, with some rubber pilots sitting in their seats.
Carved some radar, and cockpit instrumentation out of pink foam.
Gluing the canopy on. Pilot is really in there now!
Starting to construct the taileron boxes. I built, tabbed, interlocking ply pieces that contoured to the shape of the rear of the plane.
Here is the first one, glued into place with a test servo in there. I ultimately went with larger servos than this, but it was a good test fit.
Here they are all mounted. I have some real control surfaces finally.
Time to mount the fans, and tailcones. Look at those nice, pink foam tailcones covered in light glass. I turned them on a drill-press and used a piece of 80 grit sandpaper to shape them.
Mounted the rudder servos and the control rod tubes, as well as the pneumatic air tank for the retracts.
Time to build a battery mount. The tray is made out of 3/32″ birch ply with velcro straps to hold the batteries down. This system has worked quite well in other planes, and I trust it fully.
Here is a battery pack. 44 cells of CP-1700. 2kw of power ready to ride!
Starting to sheet the FOA area so the wings tuck into place.
Time to build the main hatch out of balsa, and getting it all puttied up to sand.
Covered the hatch with 1/2oz. glass cloth and resin to make it nice and strong.
Wing sweep area all done. Ready to start thinking about how I am going to mechanically sweep those wings!
Here is a jackscrew I bought from Janeco through the back of an AMA magazine.
Initial bench testing suggests that with a 9v supply, this jackscrew can supply 20 pounds of force. Here I have it hooked up to a fish scale to measure power.
My initial attempt at building a bell-crank to make the jackscrew work. I am having all kinds of problems getting the wings to sweep evenly with my bellcrank. I ultimately ended throwing this design away, because the uneven sweep issues. Another Tomcat builder in the UK, has built a promising jackscrew system using a programmed PIC and limit switches specifically designed for this Tomcat design. Here is a link to his website, for photos, and even a QuickTime Movie of the jackscrew working in his plane: http://www.freenetpages.co.uk/hp/geoff.sim/
I am very concerned that the wing pivots will be strong enough. So, I obtained some aircraft composites to reinforce them. Carbon-fiber-nomex, reinforced with kevlar cord to keep the nomex from delaminating.
After fooling with the jackscrew for over a month….I have put it aside. Here is my backup plan. 2 quarter scale servos. 12 pounds of torque, each!
Here they are mounted in the plane for some tests. I need to make some aluminum servo horns that are longer than these so I can get the total sweep out of the servos. This is where I am at currently, although some more work is going to be required to finish.
I have remounted them more securely now. I have carbon fiber rods going to the wings. I hoped to complete the maiden flight under this setup.
Oh wow! What a mean looking pair. Someone parked a small carrier air group in my driveway!
All sanded, covered with tissue, dope and sanding sealer. Then, primed with a basecoat of white, oil, primer.
First coat of ghost grey is now on her. I used Testors model masters, oil paint, thinned, and shot through an airbrush. It’s a mess to clean up, but man does it go on smooth.
Tails and cockpit area now painted black. Here it is, test fitting.
Made home-made graphics using Photoshop, and lots of pictures of real Tomcats.
Whoops! I messed up. I mounted the skids on the plane backwards, and had to rip them off. Bummer, I messed up my new paint already.
Here they are…mounted correctly. Oh well…it’s the bottom…less people will see the color issues. I thought I would add a tailhook as long as I was working down there.
Here she is…initial paint and decals applied.
LATEST UPDATE: I am still working on the wing sweeping mechanism. I started out with one jackscrew I bought via the AMA magazine, and it was powerful, but slow, and difficult to mount because it would need a bellcrank. Another Tomcat builder in the UK, has built a promising jackscrew system using a programmed PIC and limit switches specifically designed for this Tomcat design. Here is a link to his website, for photos, and even a QuickTime Movie of the jackscrew working in his plane: http://www.freenetpages.co.uk/hp/geoff.sim/
For now, I have settled on using some huge 1/4 scale servos. Here is my current setup I hope to complete the maiden flight under:
Video Clip: Tomcat Wing Sweep (Windows) - 885k – Video of the Tomcat wings sweeping. This is a short clip of the wings moving forward and back under the power of the wing-sweep servos.
Total Construction Time = Countless Hours – I started this project over a year ago, and it still is not done. Each photo at different phases of the construction represents many hours of work. This is easily the most difficult plane I have ever built, but it’s well worth it!
Here are the vital stats on the Schreiner F-18:
|Schreiner F-18 kit from Schreiner/Savex in Germany. Dieter from ShredAir in Oregon was able to import the kit for me.|
|Twin Schubeler DS-51-3PH 90mm fans. Also obtained via ShredAir.|
|Twin Hacker B50-15L brushless motors. Obtained from ICARE in Canada.|
|Twin Schultze 55bo speed controllers.|
|SpringAir 305 retracts|
|44 x Sanyo CP-1700 cells|
Unpacking and construction sequence:
The plane came in a huge box via airfreight from Germany. It showed up about a week before Christmas. Here is what it looked like when I unpacked the box, and started looking at the parts. Notice the big box in the background on the floor.
The parts were well made. The entire plane came pre-painted with lots of nice detail.
One of the most difficult parts of making EDF jets is the inlet duct forming. This kit comes with pre-formed inlet ducts, that are very well made.
The outlet ducting is similarly well constructed.
Taileron bearings are pre-installed.
Interior of the plane is bare. You need to scratch-construct the entire interior yourself. So although this plane is an ARF on the outside….it is definitely not an ARF on the inside.
Notice the detailing of the paint and decaling.
Here is what it looks after press-fitting all the parts together out of the box.
The construction started out by obtaining the missing parts…fans, motors, batteries..etc. The plane was difficult to get, the fans were almost equally difficult to aquire. These fans are also made in Germany by Schubeler Jets. They are 90mm fans, made out of carbon fiber, and are literally functional pieces of artwork.
This plane needs lots of cells. I chose to go with the 4/5 sized, sub-C cells, the Sanyo CP-1700. I did some motocalc calculations running a 90mm fan, with a Hacker B50-15L, and came up with 22 cells per motor. By going with the 4/5 sized cells, I was able to save 16 oz (a whole pound!) of battery weight over using standard sub-c’s.
The Schreiner F-18 is not designed to carry landing gear. It is designed to be a trolly-launched, belly flopper that you land on a grass surface. Since I wanted to be able to ROG, I cut holes in the bottom, and made these landing gear mounts. I mounted SpringAir 305 retracts in the plane, and used 1oz glass cloth, and epoxy resin to mount the gear into the airplane.
I made a custom fan mount out of 1/16″ lite-ply, with a basswood base. The fans are each cradled in one of these mounts.
The fans are secured to the mounts, using high-temp RTV, and the ductwork is held to the inlets and outlets using duct-tape.
Here is a shot of the battery tray mounted in the plane, with batteries in-place.
Here is a bottom view of the retract, mains. The cutouts were made into gear doors that close when the gear is retracted.
Since the plane was designed to be a belly flopper, it needs LOTS of angle of attack when rolling on the ground. The first flight was less than successful because I did not have enough AOA. I couldn’t get off the ground and crashed into the grass off the end of the runway. There is excellent video of the first flight attempts in the video library.
Here it is…all finished and ready to fly. WOW!
Total Construction Time = 6 months. The interior of the plane is completely custom made by hand. It took quite a-lot of trial and error to get everything to fit just right. It took close to 3 months to get the initial kit from the time I ordered it. It was approx. 1 year from the time I ordered it until I was ready for a maiden flight. Schreiner F-18 Videos
|Schreiner F-18 First Flight Attempt My first flight attempt of the Schreiner F-18 was less than successful. My landing gear was too far back, and not enough AOA on the wings.|
|Schreiner F-18 First Actual Flight (QuickTime) 10 meg – A few more takeoff run attempts, and it flies! Yay!|
|Schreiner F-18 Half-Moon Bay Flight Here is some footage of the flight at the Half-Moon Bay e-Fly during the Summer 2002. Good long flight movie, however, I still have yet to capture a good landing on video. Watch and see.|
|Schreiner F-18 Landing Mishap I lengthened my nose strut even more, for more AOA, and now I have some problems with ground control. I had a rough landing, clipped the safety fence at the field and tore the nose off the plane. Nothing a bit of lite glass and resin can’t fix….DOH!|