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RPM314's blog
Posted by RPM314 | Mar 21, 2014 @ 11:20 PM | 1,276 Views
Given that the structural insufficiency of MPF in the glider type wings renders the fuselage pod useless, and that I slammed the Mk.IV into blacktop pretty hard, I am making a new bird that gets back to the roots: a pure, solid wing. No bells and whistles in the layout, it will consist of a swept, tapered wing with washout, with small laminated wingtips and solid fins, and a hatch in the center. There will also be vortex generators near the wingtips, and the gear from the Mk.IV will be transferred over.

3/22: All parts are cut out, the wings are taped up and have the formers, but do not have the full compliment of carbon or the servos. Lots of sanding and taping still need to be done.

3/26: The interior of the wings are done, the fins and elevons have been sanded, and sanding has begun on the wingtips.All those parts still need to be taped over before they can be installed.

3/28: The wings are closed up and washed out and the wingtips and fins are finished and attached.

3/30: Elevons are finished and attached, ventilation has been taken care of and a battery hatch has been installed.

4/2: Motor mount is complete, but I will not mount the motor until everything else is done so I can use it to balance the plane.

4/5: Elevons now have 1/16" balsa on the underside for stiffness. Control linkages are set up and functioning, the plane is balanced at 10% MAC, the motor is mounted, stripes are on the bottom of the wingtips, and the vortex generators are in...Continue Reading
Posted by RPM314 | Feb 23, 2014 @ 04:52 PM | 1,161 Views
Hi, all. After ealizing that the gear from the Petrel was lying around being useless, I cobbled together a quick 24" wing from MPF.
The root chord is 6.25", the tip chord it 4.25", and the sweep distance is 6", with a kfm2 airfoil. It has 2 5g servos directly linked to the elevons (no pushrods), a 3A turnigy UBEC (smallest one I had), an orangerx 610 (I think) and a 2s 280mAh lipo battery. AUW is about 2oz, which is a bit heavy. It needs to be scaled up to about 30" or 36" to really float, but as is it would make a good sloper if I had a place to slope.
The maiden was today, and it flies nicely, if a bit fast for a glider. I rigged a rubber bad to hook into my friend's plane's cargo bay door, so the plane was carried on its underside. When the door was opened, the end of the rubber band came loose and the glider was released. Big cheers from all over the flying field.
Status: In service
Posted by RPM314 | Feb 17, 2014 @ 06:03 PM | 1,685 Views
Hi, all. I decided to take a crack at the hydrofoam, with my own twist of course. It will be made of MPF, colored packing tape, foam tac, and some hot glue. For the electronics, there will be an AR610 receiver, MG90S servos x3, HK 30A ESC, turnigy D2826-10 motor (1400Kv) swinging an 8x4 prop, and 3s 2200mAh batteries. I call it "Raider" because of the front halve's resemblence to a Cylon Raider fro Battlestar Galactica.
It is pretty similar to the design found at Parkjets.com, although I did not intend to make the dimensions as similar as they are. The main difference is that the prop is mounted on the tail like an airboat instead of on a pylon over the ventral pod. I did this to avoid ground and water strikes more, and because I could not come up with a ventral mounting system that did not look like garbage.
Overall length is 26", overall width is 16". There is about 1.5 square feet of lifting area, and I expect AUW to be around 16oz. It will not be 3D, but it will still be very sporty. With only red and black tape to work with, I believe I came up with a neat trim scheme, yes?
If anyone wants to reproduce it, reply to this post and I can send you the complete model and parts template.

2/18: Airframe awaits final assembly and fitting of gear.
2/19: The Rx recovered from the lightning is busted after all, so I pulled the one from the falcon for the job. The plane is complete!
2/23: Tried to fly it today, no such luck. It feels nose heavy on the...Continue Reading
Posted by RPM314 | Dec 30, 2013 @ 05:38 PM | 1,397 Views
The next iteration of the Falcon is very different from the previous ones mainly in that it is made of MPF instead of dollar tree foam. It also incorporates the wingtips from the Lightning and a similar trim scheme. There is also 3 degrees of washout to fight tip stalling, which was a serious problem on the previous models, and the wings have a taper ratio of about 2/3. Power is a Turnigy 2826-06, 2200mAh battery, and a 30A HK ESC. There are two sets of wings, a sporty and glider one, which plug into the fuselage instead of being strapped on top. As such, the wing halves are kept separate instead of hinged.

12/30: Plans are drawn out on the foam.
12/31: Parts are cut out, the sport wing has been tape covered and the spacer attached.
1/1: One of the sport wings is nearly finished, needing only a control linkage.
1/3: Glider wings are up to the servo installation stage, and the fuselage tube is ready to install equipment in.
1/5: Both sets of wings are complete and the electronics are dry fitted into the fuselage for balance testing.
1/9: The correct mounting points have been identified, still working on the actual mounting.
1/11: Mounting is done, fuselage is completed, control linkages are complete, and system check have been run. This bird is now ready do fly, maiden will most likely be this Monday.
1/20: The weather forecasters were highly inaccurate about the wind speeds, they said 12 mph and it was really twice that. The glider wing is dented and the mounting tabs must...Continue Reading
Posted by RPM314 | Aug 31, 2013 @ 09:50 AM | 2,175 Views
The cheesily named Greased Lightning will be derived from the Polaris, with a few important changes. First, it will not be a seaplane since I do not fly off of water, so some design elements regarding waterproofing can be left out for simplicity. It will still be able to taxi/take off/land on land though. Second, it will be much more efficient. The Polaris also had a low aspect ratio flat plate wing. It is simple and good for extreme high alpha and whatnot, but it is not very efficient. Cut the power and it drops like a rock, take a sharp turn and you lose half your speed. GL will have an armin airfoil wing of about 10% thickness (very thin) with large strakes to preserve the high alpha ability of the original polaris. The aspect ratio will be about 6, so it will glide well and keep speed in turns. Power will be a turnigy d2826-06 spinning a 6x4 and a 25A esc. Wingspan is 42" (~105cm) and length is 33" (~84cm).

Here are the dimensions for anyone who wants to replicate it:
The wing is made by taking a 30" section of 5" chord armin wing and cutting it in half to create 2 15" sections. These are swept 15 degrees at the root only, the tips are kept square. The wingtips are quarter circles with a radius of 6.5". The ailerons have a chord of 1.5". The strakes are triangles extending 6.5" forward and 6.5" along the leading edge of the wing. It is formed from 2 opposed trianlges with a rectangular area 1/2" wide between them (...Continue Reading
Posted by RPM314 | Aug 12, 2013 @ 08:53 PM | 2,365 Views
A 48" (1.2m) glider made of DTFB as usual. Gear is an AR600, a turnigy 3A BEC, a 280mAh 2s lipo, and 5g carbon gears. It also has an on/off switch (Fancy!) It is of conventional layout with flaperons.
The wing has 2x 20" sections of armin wing with a 4.5" chord. Wingtips are 4 layers of laminated foam sanded down to shape, with a 4" span each. Flaperons are 2" at the root and 1 1/8" at the tip, extending from the elliptical wingtips to 1" from the fuselage. It has a 5/16" wooden main spar of 42" span, a 32" span 3mm carbon spar near the top of the wing (since the top tends to compress under load), and a 16" span carbon spar near the bottom.
The horizontal stab is 13" in span, has a root chord of 4 3/4" and a tip chord of 3 1/4". The vertical stab is 6" high, has a root chord of 4 3/4" and a tip chord of 2 1/4". It also has a 45 degree bevel to allow for elevator travel. Both have a straight trailing edge. The elevator has a chord of 1 1/4". The rudder has a root chord of 1 7/8" and a tip chord of 1 1/8". Both have aerodynamic balances extending 7/8" forward and are 7/8" wide. Each has a 3mm carbon spar and they are affixed to each other by a plastic gift card bent at a right angle, mounted internally.The assembly is hot glued to the fuselage such that the elevator hinge line is at the end of the fuselage.
The fuselage is a 40" long square tube (composed of...Continue Reading
Posted by RPM314 | Jul 01, 2013 @ 05:18 PM | 1,747 Views
I plan to make another Polaris, but I do not have the resources necessary at the moment. I do have the parts for the boat necessary to run it off of water, though.
It is made of $ tree foam and put together with mostly foam-tac and some hot glue. The foam tac is especially useful for sealing the edges of the foam to keep water from making the paper peel off.
The hull outline is from Alex Tretter, the rest is me. Power is a 1300 3s lipo and a turnigy 2826-10 on a 8x4. It was a quick build, and has only been tested indoors so far.
It has a light ply hard point at the stern to attach a string with which planes can be pulled back to shore.

7/2/13: Maiden voyage on water, mulch, asphalt and astroturf. Please be aware that foam-tac is somewhat less effective at waterproofing once it has been worn away by hard surfaces. The bottom of the hull is now structurally compromised and must be replaced/extensively repaired.

For the life of me I cannot get the hull waterproofed. The paper always gets wet and peels off the foam, compromising the structure.

Status: Decommissioned for parts.
Posted by RPM314 | Jun 06, 2013 @ 08:28 PM | 1,954 Views
I have just ordered a ludicrously large BEC, and will rebuild the airframe. Just a few minor adjustments to the mk. 2. The fins will now be completely removable, because I have found that folding them under the wing creates storage and construction problems. This will allow the fins to extend below the wing to act as skids. The 25" section wing will now be included, as well as a 40" section wing. They will all have 1/8" wooden dowels embedded in the foam for strength. Also, the rear 1/4 of the fuselage pod will be removable to switch motors easily. I now have a turnigy 2826-10 for the larger wings. Because of this, all the wings will have an 8" prop slot instead of a 6".
All the wings, from largest to smallest, have wingspans of 29.5"(725mm), 42.5"(1040mm), 54.25"(1330mm), and 75.75"(1855mm). The sweep angles are 30, 22.5, 17.5, and 13 degrees respectively. This makes all the wings have the same sweep distance, and so the same CG.

6/7/13: all wings are up to the angle cut stage, and 2 of them have spars.

6/9/13: All wings have spars and control surfaces, the fins are as far along as possible without complete wings, and the fuselage is as far along as possible without the new parts. It only needs to be closed up and tapered at the nose.

6/10/13: All servos are set in the wings. Waiting for parts to progress further.

6/13/13: Parts have arrived, construction will resume tomorrow.

6/15/13: Done! Maiden will hopefully be on the...Continue Reading
Posted by RPM314 | May 23, 2013 @ 07:47 PM | 2,053 Views
This is essentially an improvement on and replacement for the Dart (now falcon mk. 1), the one lost on the island. It will have 3 wings this time, and a wider fuse pod. The 3 wings will be made from sweeping 20", 25", and 30" sections of 5" chord armin wing 17.5, 22.5, and 30 degrees, respectively. This puts the CG in almost the exact same place, eliminating the need to shift the battery. It also makes the speedier wings have a thinner effective airfoil, and the floatier wings have a lower sink rate.
It will be made of dollar tree foam board (redi-board by R.L Adams), abbreviated DTFB for the purpose of this entry, colored packing tape and foam-tac. The pictures below are of the 20" wing, the other wings being constructed the same way.
Please refer to Ed's thread in the scratchbuild forum, it tells the whole story of this construction method.

Edit (5/26/13) - 25" wing is on hold due to a miscalculation of parts quantity.
It is powered by a Grayson supersonic v2, and 40A ESC as usual. Using 1300, 1600, and 2200 3s batteries, and an orange rx. One problem with this design - due to CG constraints, the wing must be located right over the battery hatch. On the plus side, the hatch will never come off in flight. Still a hassle, though. Maiden will hopefully be tomorrow.

Status: crashed due to brownout. Will rebuild, possibly with more wing options....Continue Reading
Posted by RPM314 | Mar 28, 2013 @ 09:39 AM | 2,405 Views
Finally, after 3 months of nonstop technical difficulty (with a brief respite by the Polaris), this bird is finally airworthy. It is made of dollar tree foam board and colored packing tape using Experimental Airlines building methods.
The fuselage pod is 2" external diameter, which is a very tight squeeze, and 20" long. It is tapered down at the nose and up at the tail, and the bottom has clear acetate to toughen it up for landing. There are popcicle sticks going through the pod for wing tie downs
The wing system I am very proud of. It has two interchangeable wings. Both are 5" airfoil chord armin wings swept 22.5 degrees, but one is made from sweeping 30" sections and one is from 20" sections. So, there is a 33" and a 49" span wing for this plane. The 33" is a solid piece, and the 49" is in two halves with folding vertical stabs. When you take the spar out, it can be used to lock the two wing pieces together. The result is very compact. Both are secured to the pod with rubber bands.
I am using the same gear as always, GH supersonic on a 6x4 with a 2200 or 1600 3S. With the 2200 full forward, it balances on the 33", and full aft it balances the 49". AUW with the 2200 and 49" is about 20 oz, given the thrust to weight, and has a wing loading of a mere 8.4 oz/sq. foot! Should be a blast, pics coming soon.
Did the maiden. Word of warning: this calculator lies. It put the CG about an inch behind where it should be. The 33" just plain didn't work, and the 49" barely survived.
All fixed. As expected, the 33" is speedy and agile, and the 49" glides like a dream, gave a Calypso a run for its money.

Status: Completely intact, blown out of range, inaccessible, on an island.
Now gone, floating around in NY bay somewhere.

Edit: has been retroactively renamed
Posted by RPM314 | Feb 16, 2013 @ 07:49 PM | 2,467 Views
This one needs no introduction. 100% scale, depron, GH 2212-06 motor and 40A ESC (grayson accidentally sent me a 40A instead of a 30A). The only differences from stock is that the spars are in an A-frame configuration, because I didn't have a single carbon long enough, and there are plastic spoon air intakes. A canopy has been painted on since the taking of that picture, and it won the Foam-Tac Contest!

Status: Decomissioned (Shredded by trees. Found it hanging a few feet off the ground by the guts, looked really cool.)
Posted by RPM314 | Jan 05, 2013 @ 04:34 PM | 2,341 Views
Just built a new rack to hold planes. A couple of 2x4's (lumber, not props) mounted vertically on a wall, spaced 2 feet apart. 1/2" dowels are set into them at a ~10-20 degree angle pointing up, and they protrude 18". The result is a set of prongs that wings and sheets of depron and the like fit nicely on. Hope this is useful to somebody.
Posted by RPM314 | Dec 05, 2012 @ 08:04 PM | 2,664 Views
P115 as seen on my avatar, given to me by MeanBaby, pylon racing him at the field. (he technically won, and therefore must be crushed) There is a thread on it in the scratchbuilt forum, I think.
31" span, solid bluecor covered in packing tape, coro hatch and stabs.
GH supersonic V2 on a APC E 6x4 with a 2200mAh or 1600mAh 3s lipo. My second real scratchbuild, the construction is a bit naive, so there is a high parasitic drag coefficient. The top speed in level flight is about 50mph, way short of the motor's potential.

Status: Decomissioned (Read: FUBAR)