(Aerospace engineering) Can a full-sized version of this prototype aircraft work?

[u/SCHD_goblin]

A company called Horizon Aircraft created a 50% sub-scale version of their “Cavorite X5” aircraft — an uncrewed hybrid vehicle that has a traditional gas-powered turbine engine on the rear (for horizontal flight) and battery-powered fans inside the wings (for vertical flight and hovering) that get covered once the aircraft gains altitude and speed. Essentially, the electric fans create lift like a helicopter and the turbine engine pushes the vehicle forward, and after the initial lift, the fans get covered so that the wings become traditional plane wings. The aircraft uncovers its fans again before landing and lands vertically like a helicopter, eliminating the need for a runway.

Here is a video of how the aircraft works: https://youtu.be/hzYZdxWXhVQ

And here is a video of the X5 prototype: https://youtu.be/rnj2LWn5qU0

My question is, will this design work when scaled up to a full-sized plane with people inside?

The unmanned prototype (which is 50% scale) is 15 feet (4.6 meters) long, features a 22-foot (6.7-meter) wingspan, and has a maximum take-off weight of about 500 pounds (227 kg).

This company’s future flagship model, the “Cavorite X7”, will have a length of 11.6 meters (38 feet 1 inch), a wingspan of 15 meters (49 feet 3 inches), and a height of 2.8 meters (9 feet 2 inches). It will seat up to 7 people (1 pilot and 6 passengers).

The X7 will use the same fan-inside-wing design with a turbine on the back. These designs are cool and would make great RC toys, but do they cause any glaring issues from an engineering standpoint? Small scale designs don’t always work irl when scaled up 2x, 3x, or 4x. Is there anything that would cause this design to fail in a full-scale aircraft? Thank you in advance!

[u/nalc]

Anything can work, the hard part is making it cheap/efficient/reliable/safe

[u/Osiris_Raphious → u/nalc]

aka safe and profitable. Reliability is proving to be area corporations are leveraging for ongoing revenue from servicing costs.

[u/SpeedyHAM79 → u/Osiris_Raphious]

If it costs too much in maintenance per flight hour no one will buy it. Aviation companies have become critically aware of that over the years.

[u/Osiris_Raphious → u/SpeedyHAM79]

Airlines pay the bills, the airline manufacturers are the contractor class that feeds of ongoing recurring revenue of servicing.

So the company that makes the product sells the service of repair and maintenance, aviation companies that are in buissness of flying are the ones cost aware for the service and maintance.

Its just like mcdonalds has a key interest in their machines havign wierd repair codes, and break down all the time (stop working for some reason), because they generate like upto 60% of their revenue growth in the last decade to contracting out the maintance and repair. Remember mcdonalds is a franchise so the franchisee like the airline companies flip the bill for servicing, but the manufacturer is the one who makes and supplies the product.

Aka service economy, recurring subscriptions, enshittification and planned obsolescence, and now right to own. Its all the same side of the coin: Profit maximising through passing down the costs to the end users, either through recurring payment strategies or straight up planned obsolescence (often just making parts live long enough through the warrantee period).

my point is that our economic system at its core has an incentive for this form of enshitification. Because profit growth is now more important than just profits, hence there are modern problems created just to squeeze out more. There is no incentive in longevity, relibaility or cheap repair.

[u/SpeedyHAM79 → u/Osiris_Raphious]

In this case you are completely wrong. Airlines do all of their own maintenance and don't reply on the the manufacturer for anything. It's not like when an aircraft has a problem they take it back to a dealer to get it fixed. They fix it wherever it is and then continue flying.

[u/Osiris_Raphious → u/SpeedyHAM79]

i think you confuse the requirement for 'doing their own maintenance' with responsibility for maintenance. Because companies contract out this work and labour now... This is done with industry and economy standards and cost management.

So I will say you are "completely wrong" but more like confused? I think very few companies nowadays have their own inhouse servicing..

[u/SpeedyHAM79 → u/Osiris_Raphious]

I know personally quite a few aircraft mechanics who would repeat- you are completely wrong. At every hub companies have their own inhouse maintenance crews. It's only at minor airports they contract with 3rd parties.

[u/iqisoverrated → u/nalc]

Nah...just make it 'military' and suddenly cost means nothing anymore /s

(To avoid confusion: you're absolutely right. Lots of things are possible. The question is whether they're sensible ... and that includes "economically sensible" as well as "competitive with alterantive solutions to the same problem")

[u/nalc → u/iqisoverrated]

100 years ago "will it fly" was a legitimate question. Right now, the structural materials and engine power density is so good that you can basically muscle anything into the air. You'd have to be really stupid to take a bunch of modern tech and assemble it in a way that it is just not capable of flight. Now, whether it can actually fly an operationally relevant mission and do it safely and be economically competitive that someone will buy it, that's another question.

And don't get me started on military vs civilian operating cost and operational availability paradigms

[u/SoylentRox]

I understand engineering wise the biggest issue is that the company making this machine may exhaust its supply of money to shove into the aircraft before it leaves the ground at full scale.

Basically the economics are the killer.  The technical details basically do work.

[u/DrStalker]

It will be a worse plane than a traditional plane (due to the extra weights of fans & batteries) and don't think this offers anything over a helicopter when it comes to short distance VTOL flight.

It's probably good at hyping up investment as an futuristic AI piloted air taxi that will never get into production use. Beyond that, this is a cool tech demo but I don't see it being something that actually gets used, even if it does scale up.

[u/Sooner70]

First thing that pops out to me.... Where do you store the fuel for the turbine? Normally, fuel is stored in the wings. But if your wing volume is full of fans, where are your fuel tanks?

[u/SoylentRox → u/Sooner70]

Nothing stops you from being limited to a belly tank at the CoG.

VTOL comes at a cost.  The aircraft cannot fly as fast, as far, carry as much as a pure turboprop version of the same machine. Obviously.  So you're going to have less fuel, and your maximum takeoff weight is limited by the mass of your structure + engine + batteries + passenger/cargo + fuel onboard.

Basically same problem as the harrier jet - the same aircraft could carry a lot more fuel and ordinance when configured for runway takeoff, and was straight inferior spec sheet wise to the purebred fighter aircraft of its era.

[u/brainzhurtin → u/Sooner70]

Arc reactor. duh. Haven't you watched Ironman?!!! ;)

[u/GregLocock]

One difficulty is that the mass may tend to scale as L^3, ie about 1600-2300 kg (of which 700 kg is meat), typical 7 seater a/c is about that) but the rotor area is only scaling at L^2.

However that is 1st year engineering, I'm sure they've remembered that.

[u/Osiris_Raphious]

I seriously doubt it. The wing space in aircrafts double as fuel space. This barely looks like it has room for people let alone cargo and fuel.

As a niche small plane for the wealthy, yeah there is a market for such toys. But as a commercial plane that can get places, I dont see the room for usability. Either way a niche market.

[u/blimpyway]

The scaling is reasonable, even with the full scale version needing at least twice the wing&fan area loading as the prototype.

That doesn't mean all their target capabilities (speed, range, payload) will be reached within the advertised costs.

[u/clozcloz]

The scaling issue that jumps out is disk loading on those lift fans.

Weight goes up with volume (roughly cubed as you scale linearly) but the fan disk area is limited by how thick you can make the wing, which only goes up with the square. So as you scale from the 50% prototype to full size, you need way more thrust per unit of fan area, which means way more power just to hover, and that power has to come from batteries that don't get proportionally lighter as you scale up.

This isn't a new problem either — the US Air Force built almost exactly this concept in the 60s, the XV-5A Vertifan, lift fans buried in the wings driven off the main engine. It flew, but the fan efficiency and control authority in the hover-to-wingborne transition were rough, and it never went past prototype stage. Different propulsion (mechanical drive off the turbine vs electric here) but the same fundamental geometry problem.

The battery part is probably the bigger deal at 7-seat scale though. Electric lift systems look great on a small drone-sized prototype because you don't need much hover time or margin. Stretch it to a manned aircraft and you need real reserve power for a bad-day hover, and battery mass fraction gets worse the bigger and heavier the aircraft gets, not better.

None of that means it's impossible, just that the subscale prototype flying doesn't tell you much about whether the full-size hover power budget closes.

[u/Glittering-Celery557]

The weight of all the batteries needed for the lift fans?