"Beast One" - the next generation Microjet

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jandetlefsen

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Watched this random youtube video the other day and something reminded me of your project. Maybe you find this interesting

 

Scheny

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Watched this random youtube video the other day and something reminded me of your project. Maybe you find this interesting
Thanks! Actually I have checked all available RC aircraft and used them to research how to create a nicely behaving aircraft. As RC are steered from outside, they are not allowed to be unforgiving. But in the end, they benefit from being way lighter than a comparable man-carrying one.

Does anyone know anything about the Microjet200? Uses 2 Microturbo TRS 18-1 engines
A very nice jet, but having two turbojets is a no-go in terms of having doubled servicing costs and two small inefficient engines instead of one efficient one. As there are ballistic rescue systems available today, there is no reason in going for a multi engine anymore. A multi engine needs to sustain at least altitude with one engine out and so it will fly in cruise with only half the power and at least one third more consumption (less efficiency).
 

nicknack

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Thanks! Actually I have checked all available RC aircraft and used them to research how to create a nicely behaving aircraft. As RC are steered from outside, they are not allowed to be unforgiving. But in the end, they benefit from being way lighter than a comparable man-carrying one.


A very nice jet, but having two turbojets is a no-go in terms of having doubled servicing costs and two small inefficient engines instead of one efficient one. As there are ballistic rescue systems available today, there is no reason in going for a multi engine anymore. A multi engine needs to sustain at least altitude with one engine out and so it will fly in cruise with only half the power and at least one third more consumption (less efficiency).
Actually I brought up the micro jet 200 because it used something that has a thrust of 250lbf, if ever a turbofan of around 600 to 900lbf becomes available to public at around $100k ish, this design could become of interest.
 

opcod

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Most of those come with a nice 50hrs or max 100hr repair, sorry : mean full disasembly and ship to the manufacturer. If it's not about money and efficiency, ok.
 

Scheny

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@opcod you are right, but I think nicknack exactly meant to substitute them if such powerplant came available.

I was in conversation with DGEN, who worked on such a turbine. If I remember correctly, their initial estimate was around 80k$, but their sales told me that the price would be more in the range of 250k$, unless production numbers would be skyhigh.

So I don't expect an affordable and efficient turbofan to hit the market anytime soon. Even bigger companys like Williams had massive problems with overheating (FJ-22 cancelled).
 

Scheny

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I today created the first video showing the journey from the first design concept to the current iteration of the CAD model:
It is not a marvel of modern film production, but wanted to start small before covering an important topic.

Please feel free to ask for the next topic that i should cover and watch the video until the end (for some eye candy starting at 10:06).
 

llemon

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Just where is the intake going to be located? This seems like one of the biggest problems for a small jet like this.
 

Scheny

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Just where is the intake going to be located? This seems like one of the biggest problems for a small jet like this.
Same area as I showed with the iteration #2 model (the black one), but changed to scoops with a boundary layer diverter. CFD showed this is the best place.

Looks super-neat, but will it be cheaper/faster/ and more-fun to fly(for hours) than a twin-Jet Cri Cri or the Sonex Jet or a jet-Sailplane/soarer?
Faster than a Cri-Cri or glider? Definitely!!! (the Cri-Cri has Vne of 115kt and most gliders are not much faster)
Faster than a Sonex? Only veeery slightly, but much more efficient at that speed.

More fun to fly? Yes, as it's the only to allow inverted flight. Yes, as it much more ergonomic. Yes as it is easier to fly in some regards (less runway, better approach handling, etc.).
Cheaper? It consumes less tan the Sonex, but fuel is something which is a minor part in the total cost of ownership (turbine being the biggest).
 

Scheny

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A new video is online with a little bit of insight for the CFD testing which has been done during summer.

Please subscribe, as it is lots of work to create this videos and it will give a little motivation for making new ones.
 

ericr

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Jan 5, 2021
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Would be cool to see your CFD process, something i have very little idea about.
Engineering was done with Excel sheets, XFLR5 and now since I got the new Ryzen 9 5900X CPU, hundreds of CFD computing hours.
Very interesting project, thank you (or Dankeschoen) Scheny. I am not an aircraft designer but love engineering projects and would love to hear more about your CFD process as well. Should I assume you use your Excel sheets for “broad assumptions” and then XFLR5 for the major calculations? Is the XFLR5 what is running for “hundreds of hours”? I run Python and JavaScript processes for hundreds of hours on custom-built dual-Xeon workstations.
 

Scheny

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Hi Eric!
Excel was used for wight and balance, range/consumption estimation and for verifying the wing (lift, bending moments, etc.). XFLR is just so much nicer to use than an Excel table and gives nice curves plus a visual model instantly, but I still did an (very rough) Excel calculation to verify that XFLR has the figures in the right range. Never trust a software.

CFD is calculated with a basic mesh and a second mesh which gradually refines the cells in the boundary layer. One calculation takes about an hour on all twelve cores. This is not fine enough for professional companies, but gives me an advantage for fast iterations and the values are verified to be in the right ballpark area.

XFLR5 only takes time for calculating the polars of a foil and also there depending on how much points the foil consists of. Mine are quite high resolution, but still only take single minutes to compute. The aircraft itself calculates within 3 seconds.
 

ericr

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Hi Eric!
Excel was used for wight and balance, range/consumption estimation and for verifying the wing (lift, bending moments, etc.). XFLR is just so much nicer to use than an Excel table and gives nice curves plus a visual model instantly, but I still did an (very rough) Excel calculation to verify that XFLR has the figures in the right range. Never trust a software.

CFD is calculated with a basic mesh and a second mesh which gradually refines the cells in the boundary layer. One calculation takes about an hour on all twelve cores. This is not fine enough for professional companies, but gives me an advantage for fast iterations and the values are verified to be in the right ballpark area.

XFLR5 only takes time for calculating the polars of a foil and also there depending on how much points the foil consists of. Mine are quite high resolution, but still only take single minutes to compute. The aircraft itself calculates within 3 seconds.
Thank you for your response, Scheny. I am certain those on the Forum with extensive aircraft design experience will have more questions. But for me I plan to do a deep dive into XFLR5 to see what I possibly could do with it. Thank you for the suggestions.
 

P.68C

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Nov 6, 2021
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It will be nice to see this fly. I like the story in your first video, giving reasons why you changed from one configuration to another, while still keeping the overall aircraft very similar.
 
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