How To Build An Airplane In A Month And A Half

For the last few weeks, RC pilot extraordinaire [Peter Sripol] has been working on his biggest project to date. It’s effectively a manned RC plane, now legally a Part 103 ultralight. Now all that work is finally bearing fruit. [Peter] is flying this plane on some short hops down a grass runway. He’s flying it, and proving that you can build a plane in a basement, in under two months, constructed almost entirely out of insulation foam.

[Peter] has been documenting this build on his YouTube channel, and although the materials for this plane are mostly sourced from either Home Depot or Lowes, the construction is remarkably similar to what you would expect to find in other homebuilt aircraft. This thing has plywood gussets, the foam is wearing a thin layer of fiberglass, and the fasteners are from Aircraft Spruce.

The power system is another matter entirely. The engines (all two of them!) are electric and are designed for very large RC aircraft. These engines suck down power from a massive battery pack in the nose, and the twin throttles are really just linear potentiometers hacked onto servo testers. There’s a surprising amount of very important equipment on this plane that is just what [Peter] had sitting around the workshop.

As far as the legality of this ultralight experiment is concerned, [Peter] is pretty much above-board. This is a Part 103 ultralight, and legally any moron can jump in an ultralight and fly. There are some highly entertaining YouTube videos attesting this fact. However, in one of [Peter]’s livestreams, he flew well after sunset without any strobes on the plane. We’re going to call this a variant of go-fever, technically illegal, and something that could merit a call from the FAA. We’re going to give him a pass on this, though.

This build still isn’t done, though. The pitot tube is held onto the windshield with duct tape. The plane was slightly nose heavy, but shifting the batteries around helped with that. [Peter] is running the motors on 12S batteries, and the prop/motor combo should be run on 14S batteries — $1200 of batteries are on order. The entire plane needs a paint job, but there’s no indication that will ever be done. With all that said, this is a functional manned aircraft built in a basement in less than two months.

With the plane complete and ground tests quickly moving on to flight tests, it’s only fitting to mention [Peter]’s GoFundMe page for a parachute. [Peter] is going to fly this thing anyway, and this is a great way to deflect Internet concern trolls. [Peter]’s just short of the $2600 needed for a parachute, but if the funds received go over that amount by a few hundred, a ballistic parachute will save [Peter] and the plane.

Building An Ultralight Out Of Foam In A Basement

[Peter Sripol] is something of a legend in the DIY RC aircraft crowd. He’s friends with Flite Test, and there he built an enormous RC cargo plane that could easily carry a small child aloft. Now, [Peter] is aiming a bit higher. He’s building an ultralight — a manned ultralight — in his basement. It’s made out of insulation foam.

Yes, this ultralight is constructed out of insulation foam, but you can think of that as just a skin. The real structure here comes from a wooden frame that will be fiberglassed. The design of this aircraft is an electric, twin-engine biplane. The relevant calculations have already been done, and [Peter] is already flying an RC scale model of this craft. So far, everything is not as sketchy as it could be.

As with any, ‘guy builds an airplane in his basement’ story, there must be a significant amount of time dedicated to the legality, practicality, and engineering of said plane. First off, the legality. [Peter] is actually building an ultralight under Part 103. The certifications for a Part 103 ultralight are much more lenient than the next step up in FAA-certified aircraft, a light sport or experimental aircraft. An ultralight is not required to have an airworthiness certification, and pilots of ultralights are not required to pass any tests of aeronautical knowledge or hold a medical certificate. Yes, legally, any moron can jump in an ultralight and fly. Think about that the next time someone brings up the Part 107 ‘drone’ certification.

Next, the practicality and engineering. [Peter]’s plane can weigh a maximum of 254 pounds, and should not be capable of more than 55 knots in full power level flight, while having a stall speed that does not exceed 24 knots. This is slow for a Cessna, but just about right for the gigantic remote-controlled planes [Peter] has already built.  A few years ago, [Peter] built a gigantic remote-controlled cargo plane out of what is basically foam board and a few aluminum tubes. The construction of [Peter]’s ultralight will be a highly refined version of this. He’s using foam insulation sheets for the body of the fuselage, reinforced with plywood and poplar struts. This foam and wood build will be wrapped with carbon fiber and fiberglass sheet, epoxied, and hopefully painted with flames on the side.

The use of poplar is a bit curious for an ultralight aircraft. For the last hundred years, the default wood for aircraft has been either spruce or douglas fir. The reason for this choice is the strength to weight ratio; spruce and douglas fir have the highest strength to weight ratio of any other wood. Poplar, however, is ultimately stronger and available at his local home improvement store, even though it does weigh a bit more. If [Peter] can keep the weight down in other areas, poplar is an excellent choice due to cost and availability. The video (below) is unclear, but we can only hope [Peter] has read up on the strength of aircraft frames and the orientation of the grain of each structural member.

This is the first video in what will be an amazing build series, and [Peter] hopes to get this thing up in the air by September. If you’re concerned about [Peter]’s safety, he’s also put up a GoFundMe page for a parachute. [Peter]’s going to fly this thing if you complain or concern troll or not, so donate a dollar for the parachute if you’re that concerned.

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Homebuilt 30kV High Voltage Power Supply

If you have need for 30,000 volts to launch your ionocraft (lifter) or power other DIY projects then shuttle over to RimstarOrg’s YouTube channel and checkout [Steven Dufresne’s] homebuilt 30kV power supply. The construction details that [Steven] includes in his videos are always amazing, especially for visual learners. If you prefer text over video he was kind enough to share a schematic and full write up at rimstar.org.

The power supply can be configured for 1.2kV – 4.6kV or 4kV – 30kV at the output while requiring 0-24V DC at the input. In the video [Steven] tries two power supplies. His homemade DC bench power supply at 8V and 2.5A and also a laptop power supply rated at 20V 1.8A DC. A couple of common 2N3055 power transistors, proper wattage resistors, a flyback transformer and a high voltage tripler is about all you’ll need to scrounge up. The flyback transformer can be found in old CRT type televisions, and he does go into details on rewinding the primary for this build. The high voltage tripler [Steven] references might be a bit harder to source. He lists a few alternates for the tripler but even those are scarce: NTE 521, Siemens 76-1 N094, 1895-641-045. There are lots of voltage multiplier details in the wild, but keep in mind this tripler needs to operate up to 30kV.

Join us after the break to watch the video and for a little advice from Mr. Safety.

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