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Raptor Composite Aircraft

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wsimpso1

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Why is this thing so heavy?
We have been speculating on why for months. We do know that there was little if any weight control until is was finished and put on a scale, then everyone including PM was shocked, shocked by the number. Speculation is that the engine is heavy and we have seen some impressively thick laminations in a number of places. Beyond that PM has not gotten into how he will reduce weight towards the target values...
 

lelievre12

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You believe wrong.

It amazes me that a poster is too lazy to to spend 3 minutes on Google to fact check their own words.
I cannot find any reliable BSFC data for any Aeromomentum or Viking Valkyrie turbo (not Naturally aspirated) engines that are DYNO proved at the PROP. Its not OK to use 'vague' claims to shoot down the hard work of Jet-A engine makers especially when you are trying to nail PM to the pole. There is nothing I can see on the 'official' websites of the auto converters which support a blanket 250g/kWh. Unlike Technify and Rotax which both have this data and publish detailed information for aircraft designers.

So if you have any data which can support the vague 'modern auto engine' claims of Aeromomentum please provide a link for a TURBO version. My own view is that BSFC of turbo-Diesel is way in front (~20%) of turbo Avgas. Until then....

:popcorn::popcorn:
 
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BBerson

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Might need some anhedral to fix Dutch Roll. The VariEze has obvious anhedral. The Raptor appears to have a slight dihedral.
 

Tiger Tim

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Might need some anhedral to fix Dutch Roll.
IIRC in models there’s a rough rule of thumb that every five(?) degrees of sweep is equivalent to one degree dihedral. Surely the effect scales up though it’s probably prudent to calculate it better than that if you're making an airplane you intend to sell.
 

rbarnes

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One example: for wiring ducts he just bought a bunch of big plastic tubes from the hardware store. That's 10 pounds at least right there. There are lighter alternatives.
Worse, it's white PVC tubes, which puts out seriously toxic smoke when burning.
 

Mike0101

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EFI can be calibrated fairly well. It does usually know the delta P, though. The delta P is fixed on my car, the fuel pressure regulator having the low side plumbed to intake manifold pressure, making it really easy. Diesels are dealing with cylinder pressure. Some diesels measure this via the glow plugs. We don't know if the stock Audi or Peter is doing this.
If he can measure cylinder pressure, that should be a key tuning parameter. Too much will trash his engine, not enough will give poor power and efficiency. So, you'd have thought Motec would have given a graph for it, if available.
Perhaps I chose a bad example to illustrate pressure across a known orifice (injector, plate, spray nozzle...) can indeed result in a good/accurate flow measurement.

But since we are here, I'm 99% sure Motec did not supply any injector data for Raptor engine - too small a use case, with very little for ROI.

For reference look at Link . Refer to GM, then Ford, followed by Dodge. GM being most robust characterization of injectors. BTW Motec is similar to Dodge in baking in as much as possible, into a curve. All injectors are nonlinear when opening, regardless of type (port, dirrect, solenoid or piezo), and offset (delta of Open to Close Time), varies with pressure.

The linked data is for low pressure injectors (generally port), move onto gasoline direct injection and port injection is a cake walk. Now, move on to piezo injectors and it gets more difficult again.

EDIT - removed direct in cylinder measurement comment.
 
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pictsidhe

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Many diesels now use pressure sensing glow plugs.
There are PSGs for Audi V6s made between 2009 and 2015. I don't know if all variants used them.
 
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Mike0101

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Many diesels now use pressure sensing glow plugs.
There are PSGs for Audi V6s made between 2009 and 2015. I don't know if all variants used them.
It's obvious I don't follow diesel tech. Thanks for the correction and will update post.
 

cheapracer

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Why is this thing so heavy?
Some people understand that there is 16 ounces in a pound, and some don't, is why.


The interesting thing is that there isn’t a new video of him making 5 more ground effect runs.

Maybe he’s not quite as confident/sure of success as he indicated in the video.
Maybe that GE flight scared him enough to realise he's in over his head.

Certainly noticed his voice was unusually subdued after it considering it was it's first real off the ground moment..
 

rbarnes

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Did he ever get his renewed airworthiness cerft. back ? I remember seeing him say they came out for the inspections again, but dont remember saying he was good to go to "fly" again. Maybe he wasn't supposed to try that ground hop and he's laying low until his paper work comes back ?
 

Rod Schneider

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Did he ever get his renewed airworthiness cerft. back ? I remember seeing him say they came out for the inspections again, but dont remember saying he was good to go to "fly" again. Maybe he wasn't supposed to try that ground hop and he's laying low until his paper work comes back ?
Perf one of his recent videos, his airworthiness certificate has been renewed and updated to take the relocation to Valdosta into account... His "flight" was legal in that sense....
 
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