RFguy

I will leave the tie down points on the aircraft and limits to someone else, or the mfr but on wind force :

assume worse cases : side wind onto flat plate of fuselage +tail :

force will be (wind squared) * 0.768 * (equiv area) Newtons

wind in meters per second. area in square meters, of course.... I dunno maybe 6 sqM at 50 m/s = 11kN

and if the wind gets front onto the wing, at high AoA, lift will be produced to whatever the maximum lift is at say 100 kts wind, maybe 4x the weight ? (thinking 4g Va speed at 100 kts)....like 2400kg (24kN ?) before the plane breaks ?

alright, lets assume 24kN is the biggest number, (we have 11kN and 24kN) assuming tie downs make with the anchors at 45 deg to horizontal, rope tension will be 34kN (or ~ 3400 kg)

about 1.5 cubic meters of concrete in the ground is required to hold the plane down.

Now, that's not what might really happen in the real world case scenario.

So that brings now in to sharp focus about where you might (or if you even could ) attach anchor points to the airplane and not tear it apart.

With solar panels, in some cases it is better that their bolt break and glass comes out, rather than overturn the entire structure holding them together.....especially if on top of a building.

For anyone interested in VGs, ( I am !) here is an excellent treatment, lots of aero sim.

the meat starts at 6 or 7 minutes.

and they endorse stolspeed VGs

I wouldn't be betting my Sheep Station on it To keep the Country aspect, I reckon you are barking up the wrong tree. You don't have time to muck around with gadgets at low levels and the 45K stall speed means if there's any headwind at all and even a slight ground run, you will hit something well below 45 knots. Nev.

agreed. 45 kts is tame.

Hi marshallarts. Interesting video to watch.

It's looks very slippery. and I like canard aircraft.

If you have the aircrafts weight and lift coefficient Or still air glide performance you can work out what thrust it needs to. maintain height.. Might be about 10% of its mass for an average thing? Nev

Somewhere around 12-13% for aircraft of LSA ilk.. from my first calcs... yeah. The 500kG aircraft of LSA breed is going to need a minimum of about 60kg of thrust. as the wings get bigger, which are in the denominator on the equation, the number falls. Am calculating a bunch of zero lift drag coefficients, lift/drag and liftMax for a few Jabs, I'll see where the numbers come out. The zero lift drag coefficient is surprisingly small.

That 25kg thrust EDF is pretty good for 3.5kg ! Two of those and you might stay in the air for quite a while longer than without. One will buy you time.

Now , Ken's point- we are only allowed one engine. I bet the regulations would be behind what is possible and it would be arguable grey. You can usually win a 'safety' argument with more safety.

I'll need to read up on fixed wing flight 101 in aeronautical engineering texts to figure out what thrust is required to maintain some descent rate x. Which also means knowing quite alot about the aircraft but some gaps can be determined plugging in the known parameters. As it is not a simple power/rpm/airspeed. The interaction of prop thrust prop efficiency with rpm and airspeed is an interesting one.

However! users might know what prop RPM or engine power % can hold some descent rate x and what speed that is for what aircraft....

Actually my earlier comment of likely needing to be above best glide speed is not correct, since alternate lift/drag configurations could be generated by varying AoA, and substituting increased drag with a little bit of electric motor power.

I'll leave that one for the moment and concentrate on improving reliability with engine instrumentation.

back of the envelope....with lift proportional to velocity squared, to be useful, to extend glide range, this means (I think) airspeed has to be above the best glide speed because the wing isn't going to do much for you at low speeds. as you point out Nev, unlike the boat....you cant just fly home at 5 kts above the stall speed because the wings dont do much at low speeds without high drag devices used to improve lift. And you need power to overcome drag. I imagine there are maximum glide distance and also minimum decent rate options on unpowered descent ?

actually it weights 3.5kg, not 12kg .

14kg battery + 3.5kg EDF = 17.5kg solution...

what has to be worked out now, what is the minimum thrust that is USEFUL for glide range extension.

For "electric assist ", I would think using a ducted fan and take advantage of the high electric motor RPM capability- because it is all weight -

-you can increase the thrust with higher rpm with no weight cost.

here is an EDF with 25kg of thrust . about 1/5 of TO thrust.

https://www.turbines-rc.com/en/schubeler/2117-schubeler-ds-215-dia-hst-195mm-carbon-edf-ducted-fan-motor.html

now we're talking ! this has legs. 15kW max input. let;s got 10% below as not to run everything at max stress..... 13.5kW. 13.5kW for 10 minutes = 2.25kWh. LFP at 0.16Whkg = 14kg battery. EDF = 12kg.

in practice, the battery will need some extra discharge capacity , depending on the type of cells.

Yes, electric supercharger is more accurate.

https://en.m.wikipedia.org/wiki/Electric_supercharger

It's just a concept I think about occasionally.

In a fixcould be used? Being smaller and lighter than a conventional turbo type turbine and housing.

To start we need to understand the work to be done- as to figure out what are practical motor sizes for the compressor. Also, what sort of air charge or boost do you want ?

Who knows how to do these calcs off the top of their head ? IE work done at some flow rate at some altitude add some pressure downstream? Using a turbo housing and direct drive that with a motor might yield convenient mechanicals.

How are engines rated ? adding another 30% to an engine at max rating, how much margin you have, how much gas charge you can add without breaking something or overheating something would depend alot of the engine...and design assumptions and specs.

What ACTUALLY wears in the Jabiru pump ?

Is there some way to test the performance ?

IE: fuel pump pressure, flow, leak test ?

Gaskets are cheap.

Perhaps more suitable for another thread, but I've always thought electric turbo chargers for take off and climb could work on aircraft....

Downunder, Elaborate ?, like an electric motor driven supercharger ?

METAL CHIP PRESENT ALARMS- aviation question

I remember the dreaded chip alarm light coming on in the Jet Rangers. it meant land, now ! and check ! and sure enough, you would undo the magnetic plug with the metal continuity detector , and there would be a piece of gearbox on the sensor !. take it off, not too big ? write it down in the log, and keep flying.

How is this done in Fixed Wing ICE Aviation engines ? Is this done ?

and I would guess there is a different procedure for Aluminium bits since they are not going to stick to a magnet, more needed something like a gauze that traps and you get XY continuity , or something, or some sort of cyclone/ fluid trap that heavy particles go and they get across a continuity sensor... or an inductor sensor to sense aluminium or steel in solution etc.

-glen

Looks promising, they finally got the LiS battery out the door.

90kWh battery .. 400Wh/kg IE 0.4 kWh/kg =

225kg for the battery

as for the range- yeah 2 hours at 45kW (2x45=90) with NO takeoff and NO reserve.

45kW = 60hp of course. IE 75% for 80hp ICE engine

a little bit of hype, stretching a bit

but good progress. They need to DOUBLE the energy weight density up to at least 800-1000Wh/kg. IE up around 1kWh/kg. Then for 45kW cruise, that is 45kg per hour of flying in cruise.

anyway, I will meet Mr Rotax next week in the Brumby.

Bang handles probably have the best overall utility. Maintain your engine as best, and for all the other reasons you cannot think of, there is the BRS....

There is a part of me that thinks BRS encourages moral hazard . But I think you will find if my wing gets cut off in a mid air collision, I probably wont think that !

This has been covered numerous times in other topics... I think I'd rather fly to a clear spot on engine fail than pull a chute... and I wont be flying ANYWHERE when I cannot glide to a clear spot. And I wont spin it. Of course famous last words... ha ha.

Simple Safe and affordable is the niche we operate in. SAAA build remarkable things including Jets one off. IF you have little feel for pistons you are definitely less safe and will do more damage than otherwise. It happens all the time. A jet engine gives no warning generally but they are about 10 times more reliable but well out of our price range. Probably small ones will not be as efficient and stink and make crook noises and suck in rocks on rough strips. You can't hand prop them either.. OK if I'm Going to London or somewhere but I've done as much of that as I care for. Nev

suck in rocks, yes. indeed.

You obviously feel deeper about the engine that I ! Maybe I will grow (back) into it. I probably felt the same in my own (auto) engine building days ...

The intention would be able increase the glide time/ distance . at 3000' AGL and 10:1 glide will be approx 5nm, approx 4.5 minutes.... I know it is not that simple because of changing density, temperature etc, not allowing for height and time lost to a lineup on the ground.

Quadrupling that time I think would be useful. just ideas....

agreed, about as good as it is going to get with the above examples is 25-30kg

The turbojet option is probably the most useful. The electric motor might be useful IF the prop and clutch and engine and motor were integrated. otherwise a motor + small ducted fan - prop is all extra drag unless it is contributing.

I thought I'd start a thread on this to avoid thread drift elsewhere

I've read a bit of people's experiments. I'll summerize what I wrote into an off topic post :

electric primary, electric backup, small turbines backup

Electric is coming. but what battery? here is a discussion

As a primary source of powered flight I think we are a long way off :

60kW (80HP) direct drive electric motors are easily available, approx 4HP / kg. they run on 350-450V DC with a specific driver.

To look at battery requirements, lets look at cruise at 75% = 45kW. 1 hour at 45kW = 45kWhour (energy requirement)

However batteries....LFP (the friendly ones) energy density is approx 0.16 kWh/kg. So 45kWh worth of batteries is 45 / 0.16 = 281 kg of batteries.

There have been some endeavours down having a lightweight ICE ;like Wankel/rotary driving a generator- IE take advantage of the high energy density of gasoline .

How about a electric motor as a backup ?- to extend glide distance. Let's call it 50% of full power- - or 30kW. - approx 10kg of motor-controller.

does the motor hang underneath with some sort of high blade count small diameter prop, or clutched onto the main prop shaft with some sort of ICE engine seize clutch release ? I dunno

If we need 30kW for 30 minutes for our backup thrust, now we are looking for 15kWh of batteries = 93kg of batteries. Hmm still too much ! That's a paying passenger (or at least the person buying lunch at the destination)

However given that the backup is a one shot- we do not need to use rechargable cells. there are primary batteries (non rechargable) that have VERY high energy density

One example - Aluminium fuel cells. I used these on project 20 years ago. 1.2kW/kg . So now our 15kWh requirement above is down to 12kg of batteries. Now we are talking.

They are CHEAP but they are one shot. The water gets poured into the empty plastic container of anhydrous potassium hydroxide (powder) and its ready to go, no matter how long it has been sitting around.

There are a few other limitations, like maximum power per kg, which likely limits minimum battery size to ~ 25kg. There are a few other twists, that's just an example of the use of primary cells. (because it doesn't need to be rechargable)

Onto small Jets !

Thrust for something like a J170 with 2200 PP and prop is about 128kg ( I think !) . There are small turbo jet engines, weighing 3kg with 31kg of thrust

That's 25% of your 100% thrust, but still very useful to keep you a little longer in the air. They consume about 1 litre per minute of Jet A, diesel or kero. so 30 minutes is about 23kg of liquid fuel

There are a few manufacturers, varies from 4000 to 6000 USD. all self contained, just add fuel.

That seems like a fairly simple solution hung underneath the engine between and fore of the main gear. I will leave the balance , thrust, heat and other problems to someone else. oh hmm noise wheel in the way ? minor details !

discuss.

Jets are by a wide margin at the present but they have NO soul or character.. Nev

I don't think I want soul or character in an engine, I just want it to do its job !

Electric is coming. 45kW cont /60kW peak motor is about 20kg including controller.

batteries need to improve by 10x. that is coming, also.

Needs battery storage. 1 hour of flying is 187kg of LFP.

Maybe wankel engine from 100LL driving generator, and have say 30 minutes of batteries at 50% power ? (93 kg)

I would have though a small JET mounted somewhere would have been the ideal backup. say 25% of ICE thrust (128kg max)

$USD4000 31kg thrust, about a litre a minute of JetA or kero. weighs 3kg.

http://www.kingtechturbines.com/products/index.php?main_page=product_info&products_id=55

direct drive no good at common prop RPMs ?

back to the J200 and the 19-x question.

By the book, if you build a 19-x, once you sell it, the advantages that you had been the builder would seem to be lost, which would limit their appeal to some buyers. Is my interpretation of the situation close to the mark ?

I see ROTEC are building 7 and 9 cyl radials and well priced. I gather not mfr / maintenance cost effective compared to the flat 6 jab ? ooh I see they are heavy.