charliemagpie

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We wanted the CT in a hurry

Now It's got a Rocket up its arse :ROFLMAO:
 

SKUUT

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Someone probably mentioned this already, but you can see them raise the truck at 8:32 seconds... super quick, and it looks like the front lifts before the tail end. Lowers at around 12:14, not fast, but still cool to see... I've never seen the truck look as good as it does in the pics and videos from the launch site; we can thank the Starbase watchers for their high-end cameras 😁
 
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Plot twist: CT launched into space! What a cool publicity stunt would that be?!
 

JBee

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I’m waiting for Kerbal 2.0 to come out for the Mac, I’ve got enough Mac horsepower at the house to really do something with it.

Skylon and Sabre are an interesting concept. SSTO is the holy grail right now. But there are massive hurdles in the way. I was involved with the X-31 NASP for a while, I’ve seen enough and done enough to realize someone is going to need to come up with a stroke of genius to solve the issues we are facing. The laws of physics are a real bee-otch, there is just no way around them.

That being said, I’m reminded of a discussion Elon had about the Starship. In explaining what the Starship could do for the costs of going to space (and the beauty of the Falcon booster) he said; “Imagine what an airline ticket would cost if the planes could only be used for one flight, and then they were done.” And then you could see the wheels turning in his mind. He then said; “There’s no reason Starship couldn’t fly from the US to like, Singapore as a regular service in about 45 minutes.” And he quickly changed the subject. Think on that for a moment…
Yeah that would be crazy, but maybe a little bit sad as I enjoy the flying part, just not the sitting!

I love flying, I've spent a few months of my life in the air travelling, and I actually always wanted to become a pilot ever since I was a toddler. Everytime I saw a plane overhead, I'd point my little finger to the sky and say, "Mum, they are my friends!" Maybe I was pointing even further, who knows, I can't really remember, but that's what I've been told. My late brother always called me a "space cadet"...so maybe I'm missing my calling? :)

But I suppose by the time I do the hours to become a commercial pilot we won't need pilots anymore.

So currently the closest I get to flying is the UAV stuff I still do when I have time, we used to do fully automated SAR competitions a lot since 2012. Those were fully autonomously flying out 30km, doing a 1sqkm search grid with CV recognition, drop package near located target, return home...all without user interaction inside 60 minutes. Later versions we designed and built our own custom eVTOL quadplane platforms, that could VTOL using quad motors, fly 120km @ 100kmh with wings and pusher prop, and do all that with 1m wingspan and 3kg TOW and all powered by a battery. We even used a climb and glide flight profile regimen to reduce energy use, which can add up to 7-10% with a folding pusher prop.

Because of the addition of the quad rotor vertical takeoff system to get it straight up above the treeline, we managed to double and add 1.5kg of payload an battery to the airframe, as we weren't limited by the wings high rotation/stall speed. This was because we were using a "unlimited runway in the sky" in that the quad motor would produce lift until the wings took over in flight. Good thing about that was we could also optimise the pusher prop pitch for forward flight, making it steeper to match forward cruise speed and efficiency without much prop slip, as we didn't need a prop that wouldn't stall on takeoff. Essentially using the hybrid vtol drive-train to create constant speed prop efficiencies without the mechanics otherwise needed for it. In hover mode it also feathered and yawed into the wind, so on windy days it would hover up to altitude whilst pointing into the in wind, and pitched up in such a way that the wings produced lift from the wind in hover. It's essentially a stall-less winged aircraft that can hover and land on a dime (using RTK GPS).

But the international competition held here in Australia every year shut down because of Covid, and never restarted. :(

The design revolves around the principle that forward flight is separate from the hover VTOL mode, and because of this de-coupling, each can be highly optimised for it's specific flight envelope. Forward flight is optimised only for max cruise, and VTOL is only to hop up for 20-30 seconds to get into forward flight. The size of each system, motors, batteries etc, is tiny because of it, and the performance gains in cruise are huge because you can run a highly loaded tiny wings with low drag.

I have some plans in Inventor for a tandem 2 seater version evtol, using a slimline box wing rear pusher layout with t-tail (to keep the wings out of the prop ingestion and to reduce induced drag), as a tri-rotor variable pitch propeller design (using low-noise counterbalanced single sided "prop" that self-feather out of the wind in forward flight) and a thrust producing fuselage design with laminar air injection (which also does the bio-fuel ICE hybrid cooling - maybe even for the control surfaces in cruise). Wings are optimised for cruise only (like a tomahawk missile) so have a high stall and just enough lift for landing hot (120knots). Fuselage and wings out of CF, with battery cells integrated into wings as structural packs and to save wiring etc to the nacelle motors on the wing tip. High aspect ratio wings with glide ratio over 17:1 according to some CFD sims I ran. Pressurised cabin with performance akin to the Celera 500L at FL250...so both fast and VTOL so I can land in anyones backyard, even though I built my 3km driveway as a landing strip. ;)

Propulsion is synchronous 3 phase power with variable pitch doing constant speed stabilisation control in hover, meaning ICE/generator, tilt rotor pusher motor and two side motors on the tips are all running at the same speed, and can do so without any motor controllers in between, like an RPM locked "electrical driveshaft". Also running redundant dual coil motors (so two motors in one) with switchable individual battery backup and speed controllers for each as well, for single motor failure flight redundancy in hover. Variable pitch also means I don't need individual RPM control of each motor, and variable pitch is way more responsive for maintaining attitude control in hover than trying to accelerate the fairly large prop with RPM control. The idea with the AC phase synchronised motors and variable pitch was that it could auto-rotate like a heli (as a tri-rotor!) with either ICE, motor controllers or batteries off, on top of it's capacity to land using just it's wings and the obligatory CAPS. One trick I'd like to implement on ICE/motor failure, is to glide unpowered on the wings and use the pusher prop to spin up the rotors on zero pitch before a quick transition flip to auto-rotate and vertical touchdown.

The main reason personal flight never really took off is because people couldn't afford to pay for the landing strip to takeoff from! With this design the idea is to get from point to point in a straight line faster than an airliner, but at the same cost, all in a personal vehicle.

Anyways, maybe I should join a airplane forum... :)

P.S. Whoops, I forgot that I was actually going to tell you about my fuel-less toroidal vortex orbital launch system idea...
 
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Setok

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This is just all kinds of wrong.
Happy to be corrected. But for instance many EV vans tow half of what their ICE versions. Many EVs aren’t even rated at all for towing. You can also look up wheel drive (not motor) torque figures for a Wrangler in low range and compare to a Rivian. But happy to learn more.

Nobody doubts EVs can’t tow when built that way, but it’s not an automatic given.
 

Crissa

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Huh, the Cybertruck arrived with two white Chevrolets and the lead one had a Starlink atop it.

Tesla Cybertruck Videos of Cybertruck towing SpaceX rocket engine!! 🦾 Screenshot 2023-10-05 at 12.38.49 AM


From NSF's periodic compilation. (My fave bedtime media):




-Crissa
 

PilotPete

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Yeah that would be crazy, but maybe a little bit sad as I enjoy the flying part, just not the sitting!

I love flying, I've spent a few months of my life in the air travelling, and I actually always wanted to become a pilot ever since I was a toddler. Everytime I saw a plane overhead, I'd point my little finger to the sky and say, "Mum, they are my friends!" Maybe I was pointing even further, who knows, I can't really remember, but that's what I've been told. My late brother always called me a "space cadet"...so maybe I'm missing my calling? :)
That is some awesome stuff there! Go get your license, even if you don’t do it commercial, it fills a “void”. When you look at design, just think about this. Modern aircraft design has migrated to high aspect ratio longer wings. Not out of a desire to lower stall speeds, but efficiency. While there is an increase in parasitic and induced drag, it is offset by lower power requirements to stay aloft, thus increased range. For aircraft, this also means higher altitudes with reduced drag. Think about the U-2 aircraft. I understand that for some personal aircraft a higher altitude isn’t the goal, but since you’re pressurized, then get on up there! Also, when you look at fixed pitch, remember that with a decrease in air density as you climb, you’ll be more efficient changing prop pitch to stay at the RPM sweet spot for your prop. I’m looking forward to see what toroidal props do for small aircraft (and boats!). Your UAV reminds me of the V-22 Osprey and the designs that Bell Labs had leading up to the final V-22. Did you ever think about tilting the props to use the same ones to propel up and forward? Some small stepper motors in the wing might be the hot ticket there. 3D printing has changed UAV and small aircraft manufacturing forever.

Back to EVs… There is a guy in Southern California that has an electric car that is supposed to be insanely fast. I hear he wants to take it to the salt flats for a new EV world record. Basically, a gas turbine (using ethanol and corn oil) driving a massive generator, through a battery set to multiple electric motors. (Don’t remember how many) driving it through a racing transmission (cassette gears, changeable). Supposedly he is raising money for a “street legal” version and an “unlimited” version. The unlimited rendering that I saw was very streamlined, looked and painted to look like a corn cob (because of the ethanol/oil fuel) His comment was; “How fast can it go? Depends on how much money we get! Bigger generator, bigger batteries, bigger motors, bigger turbine all costs more money to go faster.” As I recall, his target was 300mph (~460Kph) for the street legal version. He also said their greatest limitation was traction on the salt. Adding more downforce to maintain traction at speed was costing him drag. But they had “ideas”…
 

JBee

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That is some awesome stuff there! Go get your license, even if you don’t do it commercial, it fills a “void”. When you look at design, just think about this. Modern aircraft design has migrated to high aspect ratio longer wings. Not out of a desire to lower stall speeds, but efficiency. While there is an increase in parasitic and induced drag, it is offset by lower power requirements to stay aloft, thus increased range. For aircraft, this also means higher altitudes with reduced drag. Think about the U-2 aircraft. I understand that for some personal aircraft a higher altitude isn’t the goal, but since you’re pressurized, then get on up there! Also, when you look at fixed pitch, remember that with a decrease in air density as you climb, you’ll be more efficient changing prop pitch to stay at the RPM sweet spot for your prop. I’m looking forward to see what toroidal props do for small aircraft (and boats!). Your UAV reminds me of the V-22 Osprey and the designs that Bell Labs had leading up to the final V-22. Did you ever think about tilting the props to use the same ones to propel up and forward? Some small stepper motors in the wing might be the hot ticket there. 3D printing has changed UAV and small aircraft manufacturing forever.

Back to EVs… There is a guy in Southern California that has an electric car that is supposed to be insanely fast. I hear he wants to take it to the salt flats for a new EV world record. Basically, a gas turbine (using ethanol and corn oil) driving a massive generator, through a battery set to multiple electric motors. (Don’t remember how many) driving it through a racing transmission (cassette gears, changeable). Supposedly he is raising money for a “street legal” version and an “unlimited” version. The unlimited rendering that I saw was very streamlined, looked and painted to look like a corn cob (because of the ethanol/oil fuel) His comment was; “How fast can it go? Depends on how much money we get! Bigger generator, bigger batteries, bigger motors, bigger turbine all costs more money to go faster.” As I recall, his target was 300mph (~460Kph) for the street legal version. He also said their greatest limitation was traction on the salt. Adding more downforce to maintain traction at speed was costing him drag. But they had “ideas”…
Yeah I should get it, but it's a 600km hike for flying lessons with nothing nearby. I was going to do it all in one hit in a camp one day...

The airframe is borderline LSA weight class, so technically you could use it with full fuel and just one person for long range. The two wing tip motors don't tilt, (but they might do 10degrees or so if we need the yaw control in hover) and are always facing up. Instead they are tiny electric motors (190mm Dia. 60kWp- 7kg) run a planetary gear and swing large props slowly only just for hover for low disk loading. Props are weird and similar to these (but with variable pitch and one larger prop) which makes them self feathering out of the wind to minimise drag when flying forward on the wings.

Tesla Cybertruck Videos of Cybertruck towing SpaceX rocket engine!! 🦾 1696500988509


The rear pusher prop is a much smaller diameter and is the only one that tilts between hover and forward flight, but hover thrust is asymmetric between the three rotors, being weighted to the wingtip rotors more (a bit like having a small stabilising rotor on the V22 tail to keep balance in hover). It also is 2 axis for yaw control in hover, and is essentially thrust vectoring in forward flight. Which in turn gives some more freedom to optimise the rear prop for high speed cruise, without swinging a huge prop at high pitch etc to keep up with airflow. Prop disk area thrust needs to match total airframe drag, so it's counter productive to make the cruise prop too big, smaller is better, and this way I get big rotor disk area low pitch rotors on the tips with efficiency for hover and small disk area high pitch for forward flight all in one. The rear prop/rotor is also variable pitch, so we can use it for both hover attitude control, and constant speed through climbout to high altitude cruise.

There is one more trick here, in that the rear pusher prop in cruise is direct drive for mechanical efficiency, with a shaft from the mid/rear mounted ICE (TDI 4cyl - with 2cyl split redundancy). It also drives the inline generator/electric motor on the same shaft and has a one way clutch, meaning if the ICE goes down you still have electric and vice versa. Being AC induction the electric motor/geny doesn't cause drag on the ICE or prop when it's electrically off, so I don't need any other clutch for that to run just off the ICE if the elecric motor fails. So long the bearings don't seize on the main shaft either will work without pilot interaction. Prop pitch needs to be auto in hover, but could be manual in forward flight.

FL250/300 is sort of the limit with the prop and piston ICE, given all the different flight modes it needs to accommodate, unless I go high bypass TF or Propfan! The difficulty with small turbines is getting the efficiencies up from the heat recovery, there are a few smaller high-eff. turbines in the works, but peak power levels, size, packaging, cost and fuel burn are all fairly non-competitive in that size class in comparison to a split turbo diesel piston. Even at CL500 size turbines are still borderline for efficiency, but for a two seater it's especially hard.

With the box wing stall characteristics I've been really pushing the aspect ratio, they are more like flying chop sticks than wings, because of the VTOL flight system I can really neglect low speed performance, and so you get crazy numbers in high speed cruise. The optimisation profile is to have the least amount of aircraft flying zero AoA level flight at high speed cruise, and to only produce just as much thrust from the prop as I need to overcome drag, and only as much lift from the wings as it has mass. We're talking total frontal area just over 1sqm...with wings. A glorified self propelled dart by essentially threading the needle just for cruise, and letting the other flight modes deal with everything else. Sounds "basic" but you probably know better than most that aircraft performance is highly altitude and configuration optimised, being a grand collection of compromises trying to get from takeoff to cruise and back. I don't have to land on a runway, and I don't have to optimise hover because I'm not doing it for long, so everything is minimised to the max. One day when we get high energy density batteries over 500Wh/kg, we can finally start to ignore altitude and go all the way! This is just 1st step, you can just ditch the ICE and tank and put cells in for shorter range. With ICE it should be trans-continental.

Back to normal programming! Thanks for the feedback. 😁

BTW the hybrid turbine EV guy should bring it out here, we had some records made out here on the salt flats with the Bluebird K7 at 276mph in the 1960s!
 
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JBee

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Happy to be corrected. But for instance many EV vans tow half of what their ICE versions. Many EVs aren’t even rated at all for towing. You can also look up wheel drive (not motor) torque figures for a Wrangler in low range and compare to a Rivian. But happy to learn more.

Nobody doubts EVs can’t tow when built that way, but it’s not an automatic given.
If it's using the Plaid motor drivetrain at 28,000 RPM, with the appropriate gearing the low speed torque will be enough to tow seeing that it doesn't have to geared for high speed as a truck.
 


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If it's using the Plaid motor drivetrain at 28,000 RPM, with the appropriate gearing the low speed torque will be enough to tow seeing that it doesn't have to geared for high speed as a truck.
Note I didn’t say the CT couldn’t tow a good load. Just that it’s wrong to assume EVs in general can tow more than an ICE.
 

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Someone probably mentioned this already, but you can see them raise the truck at 8:32 seconds... super quick, and it looks like the front lifts before the tail end. Lowers at around 12:14, not fast, but still cool to see... I've never seen the truck look as good as it does in the pics and videos from the launch site; we can thank the Starbase watchers for their high-end cameras 😁
I noticed this as well. The CT is sharp as hell.
 

Crissa

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Note I didn’t say the CT couldn’t tow a good load. Just that it’s wrong to assume EVs in general can tow more than an ICE.
For the same power, the BEV is going to be able to do more. Electric motors are just really capable, especially with modern materials.

The original passes through the Cascades were electrified because the steam (and later diesel) engines just couldn't do it. It's why modern diesel trains (like from the last fifty years) actually run electric traction motors.

Electric motors are just really efficient. It's why my motorcycle will go eighty miles on the equivalent energy of a quarter gallon of gasoline.

-Crissa
 

Setok

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For the same power, the BEV is going to be able to do more. Electric motors are just really capable, especially with modern materials.

The original passes through the Cascades were electrified because the steam (and later diesel) engines just couldn't do it. It's why modern diesel trains (like from the last fifty years) actually run electric traction motors.

Electric motors are just really efficient. It's why my motorcycle will go eighty miles on the equivalent energy of a quarter gallon of gasoline.

-Crissa
I agree 100%. But you are assuming the same transmission, which is broadly not the case for EVs. Low range gearing and a clutch allows the relatively poor torque of the ICE to be converted to high wheel torque and the ability to slip to get a load moving. Remember that tow rating is done on an incline (at least here).

As mentioned EV manufacturers could have the same transmission, and get even bigger benefits, but mostly haven’t (with some exceptions). Probably due to having enough torque for most uses. But this is one reason why many EVs have had poorer tow rating. Obviously that’s not the end of the story as the Lightning can tow heavy loads and probably the Cybertruck too.

But again, it’s wrong to assume that just because a vehicle is an EV that it can necessarily tow more than an ICE.
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