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.

49 thoughts on “How To Build An Airplane In A Month And A Half

      1. Presumably the rules aren’t about having two props, but about controlling two props independently. From the “short hops” video it’s clear that independent control of the two motors is important to give yaw authority on the ground, and it’s that level of control which will make twin engine planes more complex to fly and so presumably why they require their own rating.

        1. That and recovering when one engine fails on climb-out and suddenly that wing stalls because it no longer has air being blown over it, just air incoming from the forwards motion of the aircraft.

    1. FAA FAR Part 103 classification of aircraft as Ultralight does not make any mention of the number of engines, the sole distinction is between powered and unpowered flight (and all that does is increase the weight limit for the aircraft plus add some fuel, speed, and stall requirements). For all Ultralight aircraft, no pilot’s license is required to fly.

      1. Since nobody else mentioned this: kudos to you for a clear, concise, well-researched answer, instead of just randomly hitting the keyboard and assuming you are the only expert on the planet.

  1. Awesome! I was wondering if he had a seat belt… which he does. Didn’t want him to Harriet Quimby on us (there used to be an animation of the engine bucking and ejection though maybe wasn’t appropriate). Shouldn’t happen with all electric. I wonder if the RedBull foam build was an inspiration. This is even better. Way to go Peter!

    1. Helmet too, even in cars airbags are a bad compromise because it is assumed nobody would wear a helmet for safety.
      Motorcycle helmets are well designed and easy to convert for coms especially if you roll with CEP earplugs if you don’t want the Top Gun HGU look or price.

  2. I’m not sure I like the location of the motors, when one of those props flies apart it’s going to take out chunks of wing and probably the elevators.

    Also, I’d wish for the tires being a little larger and balloonier for grass field operations. Seems like they’ll find a divot and nose him over soon enough.

  3. Technically, “RAL” isn’t a great idea for a foam build… though I’ve thought rocket assisted landing (RAL) as a hover type controlled liquid rocket fuel system now with the drone control systems being so cheap… is an easy safety build. Either trajectory control to brake or flat out brake and hover to land. Either way… amazes me even the RAT systems failed in the past and screwed those potential safety improvements advancement to the market. The spontaneous ignition fuels would be disgusting, though still. Better than death and even more aircraft damage. Maybe the system can be designed with solid rocket fuels… though would be more challenging. I’m sure can be… though auger controls or something that would add more weight doesn’t seem like the first step. Was thinking might be a neat project also. The damn electromagnetic launches were a pain in the bottom to advocate and finally get on the Gerald R. Ford class carriers. I think we need rocket launches doing the take-off also as well as at airports… either steam or EMF whichever is more energy efficient (think if solar or thermal generation using the heat) though that is another Carbon fiber wouldn’t hurt either. Ballast is nice, though that is what storage room is for or a guest/co-pilot. Hope he secures the funding for the parachute. Just to be safe. This is really neat… especially watching the Red Bull build and now this. Excellent transition and inspiration.

    1. Look up Operation Credible Sport. That was going to be a mission to rescue the American hostages in Iran. A pair of C-130’s were quickly fitted with rockets for both short takeoff and extremely short landing. The retro rockets were retractable so they wouldn’t cause drag in normal flight.

      The initial tests went well, the planes could land and takeoff short enough, and climb steeply enough, to get in and out of the soccer stadium planned as the exfil site.

      Then on the final practice landing the person operating the rockets flipped the retro rocket switch before the vertical rocket switch. The plane almost completely stopped forward motion and slammed straight down a few feet without the vertical rockets’ support. Destroyed the plane but the crew was unharmed.

      A simple re-arrangement of the switch wiring would have prevented that so that if the retro switch was flipped first, all that would’ve happened was the retros lighting simultaneously with the vertical rockets.

      It would make a cool action movie, with the end changed so the rescue doesn’t have to be abandoned. Change the hostage situation to somewhere else, in present day or near future.

      1. Thanks for the reference. Good calls… you see the potential also.

        I forgot the name of the operation for the system thinking because I was more into what has been used from in regards to RATOL (looks like is the term for both) or JATO from the ground since there isn’t any other I’ve found for breaking:

        There are a few in regards to JATO:

        Looks like I forgot about hydrogen peroxide as a cleaner fuel also for a more simple designed spontaneous combustion RAL safety system. Man… 30yrs later and wow! DEW’s and who knows what City of London hideout cartel financing irreversibly brain damaged not just me along with the rest of society.

    1. Big grin and had to remind myself to breath to stop laughing. Thinking something like funding “HaD Oxygen Generator upgrade to high flow rate and quality gas separator” or “HaD Rebreathing Unit Upgrade” DIY polymer membrane or sinterer or whatever they use for separating the gases to get O2 doesn’t have the flow rate needed for weight and size requirements. I’ve never worked on gas separators, only degassing pumps for liquids. I assume they’re atomic or diatomic size for the gas ceramic or polymer separation units since they’re not a liquified gas separation method.

      1. Medical oxygen concentrators use something that adsorbs (not absorbs) nitrogen from the air. The oxygen and other trace gasses get pushed out the tube to the patient. Concentrators typically have a pair of units or dual chambers so one can be adsorbing nitrogen while the other is being purged.

  4. Wow. Excellent work and congratulations. Only complaint is, as RW 0.0.1 above said as well, tires need to be larger or landing gear taller, because he almost clipped the wing on the ground even with a fairly good landing. A bit worse and plane will disintegrate and he will end up in a hospital.

    1. Or you could take a leap into the past with nose skids that protrude forward and wingtip protectors as many of the earliest planes had.

      Also I’d be looking into the single-engine capabilities (or lack of them) so that he doesn’t wind up with an assymetrical thrust mess like Elliot Seguin just did. It might be wise to set the engine controllers up to limit the amount of single-engine thrust available to avoid instability if things go horribly wrong.

      1. Seems with the programmable capabilities of the flight controllers, can have a warning or even a servo override to monitor and stabilize the flight with the rudder if a motor has issues. Might not be a bad idea on the nose skids and wingtip protectors. Again, seems like with the gyro controls and other devices you can have servo override to auto-pilot. Amazes me what is on the market for drones now days for really cost effective and can be used with RC anything really.

        1. I literally just opened a package of solar 5×5 solar cells and am amazed at how thin, light and flexible they are. These are the ECO from qecosolar I’m refering to. The SunPower from newelectronic I haven’t even opened yet and are more efficient. They’re way cost effective from China too. I still have to test, however the customer service seems excellent.

        2. It’s worth reading the article closely.

          Autopilot or other simple measures couldn’t help in things like Seguin’s case – he was flying a Rutan “Quickie” that was fitted out with twin (big) model airplane turbines. They’d has a problem with one of the engines cutting out that they didn’t fix (likely a fuel flow problem), and he compounded this by then doing low-altitude crosswind testing on the same test day.

          So, he’s flying crosswind at very low altitude and the engine on the “low” (upwind) side quits. Adding power from the remaining engine turns turns you and pushes you over and subtracting power costs you altitude you don’t have….and there’s not enough control authority in the design to correct this or get level. No autopilot in the world will help – the airplane just won’t fly in a survivable way in that attitude and with so little power. He wound up weaving through the aircraft graveyard, center-punching a trailer at high speed and surviving it all with few injuries.

          Much as I’ve always enjoyed Sripol’s videos, his approach to this project makes my fussy safe-flying side cringe a bit. I hope he does some single engine testing (with some altitude to spare), does his control linkages properly and has a wing-spar/rigging that will take the stress.

          1. You make sense in your thought writings Thinkerer. Thanks for clarifying as does make sense. I don’t see what you are referring to in the article to read more closely (maybe you mean the youtube videos info or details in images) other than like you are describing which does have really small control rudders, stabilizers, ailerons and really wings in general issues so won’t be able to counter engine fail with glide capabilities to maintain loft and glide to a landing especially in and to counter adverse weather conditions air flows.

            The biplane design will help compared to the experimental plane design I think. I was thinking a delta wing isn’t a bad idea also. The F-117 even flew, wonder how even can without controls systems.

            I am thinking more a short take off and landing (STOL) type design would be safest if I am thinking correctly. The Rutan designs can be dangerous due to design flaws or system checks and preventative maintenance since very streamlined for energy efficiency and low drag if I understand correctly. Being really ultralight doesn’t help either. I’ve been grilled over maintenance issues growing up since my Dad was maintenance and in the service those guys would warrior style blind folded racing each other disassemble and assemble axial flow gas turbines and systems. You don’t let something like your engine having issues just be ignored. You take apart the system and see where the out of specification control point is… especially critical control points. I get the “damnit – you can kill people if you’re not being careful” voice in my head. Some systems are really dangerous to ourselves and others without proper prior planning to prevent piss poor performance. Thanks again for clarifying though problematic issues. He can remote control do most of the qualification and validation tests also.

          2. I watched some more of part 7 and makes more sense now. Scared him too I’m thinking, no part 8 yet. :-|) Can’t you still gain metrics on the motors and control systems performance if you log the values? A data logger might not be a bad idea as well as a weather station data logging concurrently too before you go out to when you land. Then you can identify trends in performance to better predict issues in your motors, controls and flight along with weather data. The videos are an excellent idea also. This isn’t my subject matter expertise though amazed me the autopilot features and gyroscope and other flight stabilization methods with the drones you can apply to aircraft also. I think the U.S. Army did that to their aircraft in general say their A-10 control systems versus U.S.A.F. A-10 control systems. Even with drones the operators requirements are different. Like your noting and I’m adding… if you don’t have enough ballast or mass and thrust to counter the wind… you’re getting blown where ever the air current is taking you… including to pieces if you don’t factor the mechanical forces like torsion, tension, flexion, compression, etc.

          3. Left engine quit, on the downwind side. Could have been a too rich flameout caused by air starvation due to the crosswind and blockage from the fuselage.

            I read their full report. What stood out as exceptionally stupid was nobody involved with the project bothered to fly the plane in its original configuration so they could become acquainted with its handling characteristics. They just got the plane then jumped right in to modifying it. Leaving the piston ending and propeller on it for test flights with the jets would have been a very good idea – especially when they knew the FADEC software was still being debugged. Could idle the piston engine while throttling up the jets, then if any problem cropped up with the jets, go full throttle on the prop and hit an emergency stop on the jets.

            Compounding the dumb was flying it with buggy control software in any sort of crosswind, let alone the strong wind on the day of the crash.

            Smart people with an insufficient level of caution and asking (constantly) “What all can I think of that could possibly go wrong with this? What can I do that has the best chance of pulling my ass out of the fire if X goes bad?” can do some amazingly dumb things.

          4. Another problem with the Quickie 2 they missed a chance to correct, had they bothered to do a minimum amount of online research, is the rudder size is barely adequate for the speed the plane is capable of with a piston engine and prop. There are plenty of reports of it having especially poor ground handling with the main wheels so far apart and the small rudder and tail wheel giving poor steering until higher prop RPM and ground speeds are reached.

            Jet engines mounted how those were would make steering worse due to not having thrust air blowing over the rudder.

            I would have made the rudder at least 2x longer (front to rear) to improve steering control authority. Calling up Scaled Composites and asking them for input on known issues with the design, and how to fix them, would have been on my list of things to do.

  5. I would not have thought of saving weight by skipping that awkward helmet. Though in the early days of hang gliding I was impressed by the number of bare-headed pilots killed by striking the kingpost in very low speed accidents.

    Very cool though. What about the dual throttles and the regulations? Not that the FFA can actually do anything to you, but in the US, the changes to the legal jurisdiction for national security means that if the authorities want to, they can make serious trouble over anything that happens in the air or on an airport.

        1. Something else. :-|) They’re different down under. Was recently trying to order some Kelvar Braid Antenna Wire and shrink wrap since the red2go have the best price and the only other place I can find is in the U.K. (nevada who doesn’t ship either though I may have found a middle man) or old Clansman Dipole Antennas. The Ausies won’t ship or do the conversion on their website. Different for sure. I do enjoy a Fosters in Tuscon for some reason.

    1. Yep. Just looking at the design, am guessing that a stall would rapidly devolve into a spin. And that rudder would not help.

      But holly cow, mother of Giuseppe, and meadow sprites, from raw materials to flying in less than two months. That is the living definition of ambition and determination.

  6. Now, shoot me down, but I’ve seen worse, heck, I’ve even flewn worse.
    But he might try and borrow a parachute from the next glider club, if he’s aiming for greater altitudes and a light helmet might be an idea. Stll, I am impressed.

  7. Definitely motivated and determined to succeed for sure. This is the only other foam aircraft I’ve seen like this with a pilot and isn’t even close.

    Traverse City, Michigan old U.S. Navy Base came out with their pre-WWII remote controlled airplanes that they could pilot and also remote control with video TV transmissions also in the 1930’s.

    Neat to see new materials that are commercial off the shelf being used. Now to increase the safety designs with control systems to assure right the first time zero injury metrics.

    I have to find the contact info of a brother from when I was attending Tech because we were thinking about making a biplane out of his woodshop though WWI style with maybe some materials improvements. Amazing how an airplane can almost be entirely made from trees you can cut out in the woods, some materials you can mine out of the ground and then processing and manufacturing operations with testing the finished result (now with cheap Chinese remote control components too if wanted or fabricate with higher quality U.S. or other countries).

    Another thing I was thinking would be hilarious would be a large surgical tubing, bungy or some sort of rubber band launcher once all the control systems are validated.

    I guess you could find a tower and pulleys and use sand bag weights also for launching now I think about it too.

  8. About the parachute requirements: I don’t know if any certified equipment is mandatory for this ultralight category in his country, but if not, he could always buy a parachute for tandem paraglider, it weight about 3kg and garanties you a safe trip to ground for load bellows 220kg. And they are fairly cheap : I got mine on the second hand market for 300€

    1. Trouble is that a parachute of appropriate size needs considerable time to deploy and fully inflate, and while 30m (close to 100ft) above ground is more then enough to kill most people, it’s nowhere enough for a parachute of this size to work properly.
      Also – a paraglider is an inflatable wing, it needs air flowing over it (and partially into it) in the correct way in order to generate lift, which keeps you from plummeting to the ground (if you stall the wing, it starts to fall), wouldn’t work too well on a suspended plane that has wings which would cause a lot of drag.

      A ballistic parachute is a completely different story, because the launch system helps with the deployment, so it works from very low altitudes.

      As for certified – you could literally build the plane out of cardboard and as long as it meets the weight and speed limits, it’s a Part 103 ultralight. Even the heavier ones can be designated as “experimental” and thus be exempt from A LOT of certification requirements. Shame we can’t have this in EU…

  9. Yes, add some solar panels which shouldn’t add too much weight if you save energy on large surgical tubing, bungy cord, rubber band or some sort of tower with a rope with sand bags, and I think three pulleys to change direction of the sandbag fall vector in between launcher is the least number, once all the control systems are validated and the safety systems are implemented. Rocket assisted take-off would look way awesome too, though with foam I’d be way to nervous. The idea of a go cart or buggy underneath to assist take-off might not be so bad. I guess a vehicle tow may work too.

  10. Twin engine sub-ultralight aircraft experiences single engine failure at 105% of stall speed on final approach while successfully lined up over centerline of runway at altitude of 2 ft. Pilot elects to pull up and bank left completing a turn directly towards the densest collection of ground obstacles available, and unsuccessfully attempts to fly in between them with flight attitude of persistent pilot induced oscillation.

    Ahhmmm….. this guy don’t need a parachute. That would just make him brave enough to do things at altitude (but would probably lack enough altitude for parachute to open.). Needs to practice basic flight control and emergency procedures WITH THE MODELS like the rest of us do until reactions become totally ingrained and automatic. If one has to stop and think the aircraft is already ahead of them. There is no time to Stop and Think. “Toy airplane” habits where one can fly without fear of loss of life are a major contributor to the incident as these are his only training.

    Upgrade the training! Self-discipline.
    Fly the box! (aka approach landing pattern). Master elevator control for airspeed control. Master using throttle control for rate of climb/descent. Be aware of ground obstacles and flight envelope capabilities. Practice engine out procedures. Be ahead of the aircraft with control inputs rather than following/reacting which result in Pilot Induced Oscillation.

    It’s no longer a toy when you get in it.

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