Weight & Balance question.

[skippydiesel]

8 minutes ago, Moneybox said:

There are not a lot of service stations where you can park your plane in the driveway. Do you have a strategy for moving those 60L to the airstrip during your cross country travels?

Yes to the strategy.

 

My plan, such as it is - in order of preference;

1. Research each fuel stop carefully, try and find the name/contact details of the local Flying Club/business, to beg a ride/ borrow a vehicle, for the, hopefully, short trip to the nearest suitable ULP provider ( this has worked before).
2. Call a taxi - some drivers may not want to carry fuel.
3. Use AvGas - made a "shandy" once - high cost, nil performance gain, got me airborne.
4. Carry some additional fuel, for on ground top up, to get me to a more helpful airfield😈

[Moneybox]

I'm not even flying yet but I expect to have a lot of trips Cue to Perth and back. My plan is to see if I can become a member of the Northam Aero Club and use that as my southern base. It's 261.9 nautical miles each way and an hours drive to Perth. Yesterday we left Cue at 4:20pm and arrived here in Bindoon at 11:38pm stopping for about half an hour at Paynes Find for a bite to eat. We are still an hour from Perth.

 

If my plan works out I'll have a little Mercedes van with a bed and basic extras parked at Northam for the travel to Perth. I bought the van to travel around the country a few years back. If that works out my van will be available to known visitors dropping in.

[T510]

I like the look of these for extra fuel if your aircraft has somewhere to mount them.

 

https://www.aircraftspruce.com.au/catalog/eppages/ultralighttank05-12347.php

 

10 gallons if you can mount two and no extra fuel in the cockpit.

[djpacro]

10 minutes ago, T510 said:

I like the look of these for extra fuel if your aircraft has somewhere to mount them.

 

https://www.aircraftspruce.com.au/catalog/eppages/ultralighttank05-12347.php

Not going to get approved for a "FACTORY BUILT TYPE ACCEPTED 95.55", especially an LSA. You'd need to prove compliance with the ASTM specification.

 

[Moneybox]

1 hour ago, T510 said:

I like the look of these for extra fuel if your aircraft has somewhere to mount them.

 

https://www.aircraftspruce.com.au/catalog/eppages/ultralighttank05-12347.php

 

10 gallons if you can mount two and no extra fuel in the cockpit.

 

Not going to be approved but if I mount a few low enough it could expand my options on where to land 🤪

Edited February 12 by Moneybox

[T510]

2 hours ago, djpacro said:

Not going to get approved for a "FACTORY BUILT TYPE ACCEPTED 95.55", especially an LSA. You'd need to prove compliance with the ASTM specification.

 

As the owner of a 10 reg plane I forget the hoops others have to leap through

[BurnieM]

If you have 65 litres, lets say 63 litres usable.

912ULS comsumption of 18 litres per hour at 100 knots.

Distance 262 nautical miles, lets add 10 nm each end for manouvering, say 282 nm trip.

Time with zero winds would be 2 hours 49 minutes.

51 litres would be used plus 30 minutes margin (9 litres) so 60 litres total.

 

No allowance for headwinds which you would need to monitor.

You need to confirm that your tank actually holds 65 litres.

Also confirm your fuel consumption of 18li/hr.

 

You may already have (just) enough although I would probably do some research on alternate fields 30 minutes before your destination (both ways).

 

Edited February 12 by BurnieM

[Flightrite]

Personally I use 60 mins res everywhere drive my planes, remember min 30 mins is what you must have at the completion of landing, that’s cutting it too fine for me.

some years ago I was about to join the circuit after a lengthy flight to a drome where there was a 25 kt westerly and EW & NS Rwy’s, only trouble was that a plane had flipped on landing on the EW strip and people where frantically trying to remove the driver so hence to say either take the 25 kt X wind or divert elsewhere, hence 30 mins to me is not enuf!
I even double the min gas on the Jet I fly as well!

[skippydiesel]

1 hour ago, BurnieM said:

 

912ULS comsumption of 18 litres per hour at 100 knots.

 

 

Hi BurnieM - Where does the 18L/hr @ 100 knots come from?😈

[BurnieM]

7 minutes ago, skippydiesel said:

Hi BurnieM - Where does the 18L/hr @ 100 knots come from?😈

We use 16 li/hr for a 912IS.

 

I have heard 16-20 li/hr for 912ULS.

Thinking it is not quite a good at cruise as an IS but needs to be confirmed.

 

[Moneybox]

2 hours ago, BurnieM said:

If you have 65 litres, lets say 63 litres usable.

912ULS comsumption of 18 litres per hour at 100 knots.

Distance 262 nautical miles, lets add 10 nm each end for manouvering, say 282 nm trip.

Time with zero winds would be 2 hours 49 minutes.

51 litres would be used plus 30 minutes margin (9 litres) so 60 litres total.

 

No allowance for headwinds which you would need to monitor.

You need to confirm that your tank actually holds 65 litres.

Also confirm your fuel consumption of 18li/hr.

 

You may already have (just) enough although I would probably do some research on alternate fields 30 minutes before your destination (both ways).

 

Yes I realise the limits that’s why I’m talking extra fuel. I’ll know more after I get registered and in the air. 

[Moneybox]

I have an inflight adjustable propeller that might give it an edge?

 

[skippydiesel]

Wikipedia: 110 knots @ 75% power

 

Rotax 912ULS, 75% power, would be 5000 rpm for a 14L/hr fuel burn. This is about what I get & conservatively plan at 15L/hr.

 

So assuming Moneybox Sportstar engine has been well tuned/running as expected, he should be able to achieve;

• 65 L / 15 L/hr = 4.3hrs duration to near empty tanks.
• Dont want to risk that, so allow 10L @ reduced power 14 L/hr power for 42 minutes reserve.
• 55L / 15L/hr = 3.66 hrs duration  x 110 knots, for a still air distance of 402 Nm (744.5 km)

 

So Northam at 262 Nm /110 knots, 2.6 hrs (still air) fuel burn @ 15L/hr 38.5L consumed, leaving  26.5L (1.7hrs) should be no problem at all.

 

( Ground speed (not air) is the deciding factor - its very easy to have a 25 knot head wind that will reduce your range to a white knuckle approach to Northam)

 

He will still need some way of transporting ULP from servo to Northam airfield, for a safe return to Cue,  but I think he has that covered.😈

Edited February 12 by skippydiesel

[Moneybox]

2 minutes ago, skippydiesel said:

Wikipedia: 110 knots @ 75% power

 

Rotax 912ULS, 75% power, would be 5000 rpm for a 14L/hr fuel burn. This is about what I get & conservatively plan at 15L/hr.

 

So assuming Moneybox Sportstar engine has been well tuned/running as expected, he should be able to achieve;

• 65 L / 15 L/hr = 4.3hrs duration to near empty tanks.
• Dont want to risk that, so allow 10L @ reduced power 14 L/hr power for 42 minutes reserve.
• 55L / 15L/hr = 3.66 hrs duration  x 110 knots, for a still air distance of 402 Nm (744.5 km)

 

So Northam at 262 Nm /110 knots, 2.6 hrs (still air) fuel burn @ 15L/hr 38.5L consumed leaving  26.5L (1.7hrs) should be no problem at all.

 

He will still need some way of transporting ULP from servo to Northam airfield, for a safe return to Cue,  but I think he has that covered.😈

I wish I could confirm everything you say skippy but it's a bit difficult to calculate while the plane is sitting in my backyard and I'm sitting in a no-stopping zone in Perth. I took the opportunity to change a LF wheel while I was here because I had to be broken down or have Mrs M walk a very long way to the hospital.

 

 

I have to slip off my Clark Kent jacket every time I change one of these wheels because they weigh as much as I do.

[Red]

Whilst recognising I live in a tiny country so may well not appreciate the reality of flight in Australia, are there not a few strips along your routes wher you could refuel?.

Though I have done 7 hours in a day, I tend to need to get out and stretch my legs (and back) after a couple hours flying anyway

[skippydiesel]

"I wish I could confirm everything you say skippy but it's a bit difficult to calculate while the plane is sitting in my backyard "

 

I hope you will take the time to test fly the Sportstar - a significant part of this will be calculating fuel burn at diffrent power settings. 

 

Fill tanks to brim, Load passenger seat (if no passenger use ballast) Go fly for, say,an hour. I would start with a high power setting (worst case/highest fuel burn) 5500 RPM  - Note altitude, OAT, Indicated airspeed & Ground speed- Land  Note time (Hobbs) Measure fuel into tank to same level. Calculate fuel burn/hr at that setting. Same process at lower power settings. I would not go below 4800 RPM.

 

The result will be average fuel consumed for the whole flight, including run up, taxi, climb, cruise descent. Try for consistency. 

 

Rotax publish estimated fuel consumptions at various settings;

 

 Cruise (98 RON)

• 4800 RPM, 65% /29.5Hg/13L/h
• 5000 RPM, 75% / 29.8Hg/14L/h
• 5200 RPM 30.0Hg/15L/h
• 5500 RPM 30.1Hg/19L/h

 

I think these are correct (not sure)

 

[Thruster88]

1 hour ago, skippydiesel said:

Wikipedia: 110 knots @ 75% power

 

Rotax 912ULS, 75% power, would be 5000 rpm for a 14L/hr fuel burn. This is about what I get & conservatively plan at 15L/hr.

 

Skippy you need to use a calculator. 75% of the 100% fuel flow will be 0.75x27 lph = 20.25. L

 

5000rpm will only be 75% power if the propeller loads the engine to 75% and this will only be correct for one altitude. 5000rpm at 2500 feet is much more power than 5000rpm at 7500 feet.

 

Performance charts for any aircraft will only be correct if the factory propeller is fitted. If the propeller is ground adjustable all bets are off.

Edited February 12 by Thruster88

[Blueadventures]

5 minutes ago, Thruster88 said:

Skippy you need to use a calculator. 75% of the 100% fuel flow will be 0.75x27 lph = 20.25. L

 

5000rpm will only be 75% power if the propeller loads the engine to 75% and this will only be correct for one altitude. 5000rpm at 2500 feet is much more power than 5000rpm at 7500 feet.

 

Performance charts for any aircraft will only be correct if the factory propeller is fitted. If the propeller is ground adjustable all bets are off.

This is the Rotax reference for info as well.

Rotax 912 ULS performance data.pdf

[Moneybox]

2 hours ago, Red said:

Whilst recognising I live in a tiny country so may well not appreciate the reality of flight in Australia, are there not a few strips along your routes wher you could refuel?.

Though I have done 7 hours in a day, I tend to need to get out and stretch my legs (and back) after a couple hours flying anyway

There are only a few airstrips en route and I don’t know that any have fuel. Two of them are in military training space so can only operate on weekends. There would plenty of private unmanned or abandoned airstrips, enough to stop off and refuel with onboard fuel. If I add extra fuel later on I will most likely have a transfer pump so that it can be added inflight. 
I’ve just been looking at another Sportstar that I attempted to buy last year. It has twice the fuel in wing tanks but the owner has gone to ground, uncommunicative. It’s also been out of registration for several years but is an LSA so different rules apply when reviving it. 

[skippydiesel]

2 hours ago, Thruster88 said:

Skippy you need to use a calculator. 75% of the 100% fuel flow will be 0.75x27 lph = 20.25. L

 

5000rpm will only be 75% power if the propeller loads the engine to 75% and this will only be correct for one altitude. 5000rpm at 2500 feet is much more power than 5000rpm at 7500 feet.

 

Performance charts for any aircraft will only be correct if the factory propeller is fitted. If the propeller is ground adjustable all bets are off.

I am working from Rotax published data AND my own experince of, about 15 years, flying behind a Rotax 912ULS - you want a working fuel consumption figure + a conservative fudge factor for planning purposes - you now know how to arrive at it😈

[Thruster88]

9 hours ago, skippydiesel said:

I am working from Rotax published data AND my own experince of, about 15 years, flying behind a Rotax 912ULS - you want a working fuel consumption figure + a conservative fudge factor for planning purposes - you now know how to arrive at it😈

I agree you can get 14 lph but don't call it 75% power. The rotax charts that Blue posted show the fuel consumption at 75% which rotax say is only 68hp, weird maths if you ask me but anyway that is 18.5lph.

 

The altitude chart is very informative. 

 

 

[PapaFox]

58 minutes ago, Thruster88 said:

The rotax charts that Blue posted show the fuel consumption at 75% which rotax say is only 68hp, weird maths if you ask me

I think you'd find that is based on the 90hp max-continuous rating at 5500rpm, not 75% of the maximum power possible

[skippydiesel]

Doubters may debate all they want - my information is from the real world;

• ATEC Zephyr, Rotax 912 ULS, Fiti 2 blade ground adjustable prop, optimised for TO - 100 knots, 5200 rpm, consistent slightly  over 12L/hr - flight planned at 13L/hr single pilot, 14L/hr two up - always had more fuel in the tank, at end of flight, than planning indicated.
• Sonex Legacy, Rotax 912 ULS, Airmaster CS 3 blade prop, 130 knots, 5000 rpm, still working on it however seems to be consistent at around 14L/hr, currently flight planning at 15L/hr.

While engine setting RPM, pressure altitude & load will influence the fuel burn, for a given airspeed, I  like to have a conservative fuel burn figure that I can use for flight planning. I am not intersted in minimal fuel to get the job done.

 

Back to Moneybox's commuter flight, Cue- Northam.

The only concern I have with my fuel calculations, is the Wikipedia information of 110 knots @ 75% power - should this be significantly incorrect, then the fuel planning is out. This is where my advice for real world performance testing comes in. Go fly at various power settings (preferably with full load on board) , work out the fuel burn for the whole flight - decide at what airspeed/power you will commute at and use this fuel burn + fudge factor/speed to flight plan. Not rocket science😈

[facthunter]

What's "Fudge factor/speed"?  Ground Nautical miles/litre would be a real world performance indication. Nev

[Flightrite]

….oh it’s becoming rocket science😂😂