Big Engine, Small Airframe: Did we reach the limit?

hey everyone Riley here with dark Arrow we've been finishing up the engine installation on the dark R1 prototype to get it ready for flight testing we've already run the engine a few times during ground runs and taxi testing but we had some Hardware items firewall forward that were only suitable for ground operations we've updated that Hardware so now the engine's ready for flight testing we thought this would be a good time to talk through the engine systems and also cover some of the challenges we tackled to get to this point we'll pull the calling off and take a look at the engine good [Music] now that we have the cowlings pulled off we can see the engine this is the UL 520is made by UL power in Belgium it's 200 horsepower it has six cylinders and it's direct drive we designed the darker one specifically around this engine so we have a pretty tight packaging of the engine in the engine compartment what made the installation of the engine a little bit more challenging is that we have a baggage space directly behind the firewall we haven't talked about this a lot but we actually have two Ford baggage compartments left and right they're directly behind the firewall and each one can hold roughly a carry-on size bag this is in addition to the AFT baggage space that we have behind the cabin normally on light aircraft you only have an aft bag of space and the problem is as you load this aft baggage base up the airplane gets tail heavy the benefit of having both a forward and half baggage space is that we can bounce the airplane out and keep the CG in an acceptable Envelope as we load up the airplane in order to fit a carry-on size bag in these forward baggage compartments we had to maximize the volume we had available there we did that by moving the firewall as far forward as possible up towards the engine so we only have about four inches of space between the firewall and the engine normally on small light aircraft you'd have about 12 to 16 inches of space so we have a very short space between the engine and the firewall in fact our engine mount is so short it's really just a spacer so the bolts to attach the engine to the engine mount go directly through the engine mount and attach the engine directly to the firewall moving the firewall up gave us the space we needed in the baggage area but then the trade-off was that we had less space for the engine and the accessories that support the engine all these engine accessories have their own unique functional requirements and mounting constraints the oil cooler is one of the larger accessories that we had to fit firewall forward so this is one of the first pieces of Hardware that we positioned because there are limitations on where we can get it to fit it requires a supply of high pressure cool air on the inlet side of the cooler and then it has to exhaust to a low pressure area the cool air is fed through a duct that would be connected to this Inlet we don't have the inlet docked connected but to attach right here and then it exhausts right next to the cowling exit so it's a very short path for warm air to exit the cooler and exit the cowling one of the things we did to maximize what we're getting out of the space taken up by this cooler is we integrated the cabin heat into the system there's a small duct attached to the exit side of this heat exchanger that diverts some of the warm air coming out of it and sends it into the cabin and then there's a valve on the firewall that the pilot can open or close to throttle the amount of warm air coming into the cabin normally you'd have a separate heat exchanger attached to the exhaust to pull hot air off the exhaust and send that into the cabin that'd be extra parts and extra weight and also take up extra space under the cowling so we decided to integrate that system into the oil cooler and get double duty out of this heat exchanger another challenge brought on by having the baggage space directly behind the firewall is that it put limitations on where we could cut holes through the firewall for electrical wires or fuel lines so you can imagine that if we cut a hole through the firewall for a fuel line that went into the baggage compartment that would just interfere with space that we already set aside for baggage there are some other interesting accessories on the other side of the firewall we'll step over and take a look at those this is the battery cooling box it's another one of the larger accessories that we had to mount firewall forward and this keeps the battery at a stable temperature there are limitations on how hot the battery can get so we have to protect it from the engine if we were to mount it on the cold side of the firewall if it failed it could present A Hazard to the occupants of the aircraft so for safety reasons we're keeping it on the hot side of the firewall but then we're actively cooling it it gets cooling air from these air boxes this engine is air cooled and these air boxes direct air over the cylinders to keep them at the right temperature we're stealing a little bit of that air and bleeding it off into our battery cooling box we'll probably have to play with this a little bit in Flight testing to get it dialed in and functioning the way we want but this is our strategy for keeping the battery at a stable temperature another packaging challenge firewall forward was the nose gear it's actually sitting far enough forward that it's sharing space with the engine in the engine compartment it has to be this far forward because we're trying to get the weight distribution correct on the landing gear we want to see about 15 to 20 percent of the weight on the nose gear for proper ground handling characteristics so this is the location it has to be to get that weight distribution right if we move it further aft there'd be too much weight on the nose gear problem is when we move it this far forward it's fighting for space with the engine we actually have the nose gear mounted on two arms that extend forward from the engine mount to support the trunnion and the pivot point for the nose gear we went through a bunch of different iterations on this to get the geometry and retract mechanism the way we want and this is the final result all this Hardware the engine the nose gear and the accessories have to fit underneath the cowling which is an aerodynamic fairing that encloses all this to keep the nose of the airplane smooth and streamlined our callings are made out of carbon fiber composite and we molded them using an infusion process infusion is pretty nice because it makes a really smooth cosmetically clean surface finish on your part but it also keeps the part lightweight one of the keys to getting infusion right involves having a high quality mold we made our molds using CNC machine patterns if you're interested in replicating these results on a composite project you're trying to tackle we teach courses in Aerospace Composites and mold making I'll leave a link in the description of this video if you want to learn more about that that's about all I wanted to cover in this video about the packaging challenges of the engine installation we have some other projects we need to tackle before we get into flight testing and we'll be covering that in upcoming videos so stay tuned for those otherwise thanks for watching we'll see in the next video [Music]

Channel: DarkAero, Inc

Views: 76,045

Keywords: experimental aircraft, carbon fiber, experimental aircraft build, darkaero, darkaeroinc, carbon fiber plane, airplane build, experimental airplane, experimental airplane build, experimental airplane kits, homebuilt aircraft, homebuilt airplane, homebuilt aircraft construction, building an experimental aircraft, building an airplane, ul power, ul520is, naturally aspirated, airplane engine, aerospace, aerospace engineering, mechanical engineering, aeronautics, engine, propeller

Id: VmPNRMDD1ZU

Length: 6min 27sec (387 seconds)

Published: Sat Jul 01 2023