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Member postings for Frank Skilbeck

Here is a list of all the postings Frank Skilbeck has made in our forums. Click on a thread name to jump to the thread.

Thread: Found somewhere to fly!
05/08/2019 16:01:52

And most of all, enjoy the time with your two kids, they'll be grown up in no time.

Thread: Multiplex Vario/Altimeter vs UniSens-E
05/08/2019 11:03:55

Yep, used both, and the SM Modelbau GPS logger, aerobtec Altis GPS unit, and home made Arduino vario,

The MPX and Unisens are both very easy to use (on M-Link), the MPX vario comes configured for M Link operation so is just plug and play but is easily changed on the MPX launcher program (using the MPX USB adapter). The Unisens you would have to hook up a PC, either with their com cable or a MPX USB adapter, to set to M-Link and adjust the settings, very easy to do, but the software is all in German so you'll need to download the English manual and work your way through it.

I use the Unisens E in my electric gliders so I not only have vario but can monitor the flight battery too and the MPX vario in pure gliders. My mate has a Cockpit Sx 9 and uses some of my homemade arduino varios in his gliders.

Thread: Futaba 9CAP.
04/08/2019 16:23:02

Probably a faulty tx pot on that stick (aileron?), I know the guys in our club who used to have old 9 CAPs changed out the pots periodically.

Thread: Can you charge a LiPo through its balance lead?
01/08/2019 13:01:40

I have an e-flite charger that charges 3s and 4s batteries through the balance lead at upto 3 amps. (it's the one that came with the original Habu EDF I think).

Thread: Latest Lemon DSMP/X 7 check Plus Stabiliser
31/07/2019 12:40:15

I assume when you say ballooning you mean that the model raises it's nose.

If you have a mix on the elevator and you are in heading hold/self leveling mode the gyro will see that as an instruction to rotate the plane around that axis and move the control accordingly, so best not to have a Tx mix active in those gyro modes.

Thread: Finding Models
30/07/2019 17:40:56
Posted by David Davis on 30/07/2019 16:07:22:

Martin I had an even more bizarre experience a couple of years back. There were two of us at the strip at the time and the field downwind of where were were flying was sown to rape, again it was nearly ready to harvest so the plants were two metres high. The other chap was flying a drone. I heard him cry out as he lost control of the drone and it crashed into the rape. I landed my model and we began an intensive search of the area where he said it had gone down. An hour later and we were about to give up when I felt something touch my leg. It was his drone!

Maize field this time, drone pilot crashed, we spent a couple of hours looking with no joy, we went as far to tell the farmer there was a drone in the field with a lipo attached (he wasn't concerned), then a week later a fixed wing deadsticked into the same field, walking to get that he stumbled across the drone.

Also what we've had to do when modellers go to find a model is get them to take a flag on a stick, and we can then communicate via mobile where they are and direct them to the model.

Thread: Electric Cars.
29/07/2019 17:02:52
Posted by Erfolg on 24/07/2019 00:07:14:

It was very interesting to me in that i stated i wanted a vehicle that would reliably undertake a round trip journey of 140 miles daily, without charging, in the depths of winter and extremes of summer. You will all recognise what i want, heated seats, windscreen demisting, cabin heating and air conditioning to maintain 20C. Of necessity there would be quite a bit of stop and start driving. His opinion that i would be pushing the extremes of the capability of the vehicle, under some conditions.Although the vehicle was supposed to have 250 mile range

Shame really, if you commuted 140 miles per day for 200 days per annum thats 28000 miles, approx 2500 litres of diesel (51 mpg) at £1.30 is £3250, an electric car doing 4 miles per kwh would be 700 kwh per annum at the average UK peak rate of 14.37p/kwh is £1005 pa and off peak of 8.7p £610 pa. Not taking into account the reduced servicing costs. Plus if you charged at home you wouldn't be visiting a garage every 4 days or so.

But a better option would be to work nearer home................................

Thread: Old Fuel
29/07/2019 16:37:13

They are full unused/unopened containers stored in a shed/garage, I'll give them a go and report back.

29/07/2019 07:59:57

I have been given a couple of gallons of Southern Modelcraft 0% nitro synthetic fuel which is approx 10 years old, while it is in unopened sealed containers it appears slightly darker than the fuel I bought last year. Is it worth giving it a try?

Thread: Electric Cars.
29/07/2019 07:54:19
Posted by Rich too on 29/07/2019 06:39:24:

One thing a had not given any thought to previously was heating and air con in an EV. Winter especially must put massive load on the batteries, defrosting and heating the car on a freezing morning....

Yes, but a bigger impact is the reduced performance of the batteries at cold temperatures which is an even bigger impact on range. Some manufacturers have battery heating systems to combat this but this too uses power.

On the flip side a lot of electric cars allow you to preheat therm, so you could do this while they are still hooked up to the charger, so you wouldn't need to start the engine and then walk round scraping the windows and the car would be nice and toasty when you get into it.

28/07/2019 17:01:51
Posted by Erfolg on 28/07/2019 11:07:31:

Frank

The kettle is a very good example of real world economics. It is considerably cheaper to use gas than electricity to boil a kettle.

 

Edited By Erfolg on 28/07/2019 11:11:29

Agreed, using gas for heating is quite efficient, but using gas or liquid fossil fuel to provide mechanical energy isn't and thats what I was referring too.

As regards power generation a combine cycle gas turbine which uses the exhaust gas to produce steam to drive a steam turbine give an overall thermal efficiency of over 60%.

Trevors maths were not 10:1 but 5:1, but one of the advantages of electric cars is that they recover kenetic energy when they slow down and don't use fuel when they are stopped in traffic, plus an IC engine is only at it's best efficiency when it's running at a specific point, so real world efficiency is much less.

I'm not trying to be selective I understand the limitations of electric cars and drive a diesel myself, but have to admit that in terms of overall pollution per mile driven then an electric car produces less pollution. Note the average CO2 emissions per kwh in 2018 were 270 g/kwh ( last 24 hrs 212 g/kwh), a Nissan Leaf will do 200-240 miles, say 320 km on 60kwh, so that equates to 51g/km. Not great and the UK has one of the lowest power generation CO2 emissions of all developed countries (down from over 500g/kwh a few years ago), mainly due to the switch from coal to combined cycle gas.

Edited By Frank Skilbeck on 28/07/2019 17:09:29

28/07/2019 08:30:08

Ereflog, boiling a kettle is a poor analogy as the thermal efficiency of this is typically 80% plus, now when you convert that energy to mechanical efficiency then that is not very efficient because you can't recover most of the energy, which is just expelled as heat.

Also combined cycle gas power generation is a gas turbime running at circa 30% efficinency and using the exhaust gas to generate steam to run steam turbines, to being up the overall efficiency. This is now most of the fossil fuel power generation in the UK.

27/07/2019 22:54:05
Posted by Nigel R on 27/07/2019 22:22:19:

Frank

You've missed the grid transmission efficiency and battery charging efficiency.

I've read that the oil we use in our cars, as much is used again to get it there. I'm unsure how accurate that is though.

Yes, but I didn't take account of the losses in the supply of petrol/diesel either.

An interesting concept is EORI which the a measure of the energy ratio to extract fuels, which is going down as oil extraction is become more difficult as the easy to access reserves have been exploited, renewables are becoming competitive on this basis, **LINK**

Edited By Frank Skilbeck on 27/07/2019 22:54:52

27/07/2019 22:33:59
Posted by Cuban8 on 27/07/2019 21:35:47:

Forget motors, compare the volume of a single gallon of diesel (gallon fuel can dimensions) that can take my Mondeo....easily 50 miles. How far would your typical EV get on a battery of similar size / volume. Scale it up to your heart's content, the figures are still against batteries. I've gone 500 miles when working in Scotland (reminds me of the Proclaimers song) between fill-ups of the Mondeo's large tank, batteries don't come close. The energy density of batteries still needs work as does the time taken to fill them.

Yep a 60 litres of diesel has around 640 kwh or energy compared to the 60 kwh battery in a new Nissan Leaf+ that is only good for upto 240 miles.

Thread: Building in washout...
27/07/2019 20:37:13

It's easier to put the twist in along the complete wing, it also means that the airflow over the wing stalls from the center outwards.

Note the purpose of washout isn't to delay the stall, but to encourage the airflow breakaway in the center first so the wing tips keep flying. That way the plane will either drop it's nose or mush along nose high losing height, but it will avoid suddenly dropping a wing. Note the wing will stall when the angle of attack is too high, I once had a plane that had a vicious stall coming out of the bottom of a loop if you pulled too hard on the elevator, but was reasonably easy to land.

Thread: Electric Cars.
27/07/2019 20:04:12
Posted by Erfolg on 27/07/2019 11:39:36:

What tends to distort the issue is that IC vehicles are in general more efficient than electric vehicles when all the losses are considered.

Can you back that up, the best fossil fueled power plants, gas fired combined cycle plants, have a thermal efficiency of over 60%, and an electric car is over 85% efficient, so that's an overall efficiency of 50% or so. And the engine thermal efficiency you quote is an engine running at optimum conditions, say cruising at 55 mph maybe, plus that doesn't include the losses in extraction, transportation, refining and then distribution of liquid hydrocarbon fuels.

Thread: Building in washout...
27/07/2019 16:26:21

No No, the tips should have a little less incidence than the wing root, that way the wing stalls in the center first, "stalling" the dreaded wing drop.

You don't need much 1 to 2 degrees is fine. Normally when you are building a wing you'd fit the leading edge sheeting with the wing supported by wing rib jibs which are set to give the correct washout. But if you don't then just calculate the amount the trailing edge at the tip has to be raised and and pack it up a bit when building. If it is built already you can build the twist in when covering, but just make sure both wings are the same.

The other thing that is worth doing is making sure that you have some aileron differential, typically start with the up aileron movement being 2x the down.

Thread: Phase 6 or middle phase electric conversion
26/07/2019 08:18:58

Having built a Phase 6 many years ago, fitting an electric motor wouldn't be easy as the nose section is quite thin.

If I was doing it then I'd build two fuselages, one as per design for slope soaring and 2nd modified to be wider to take a decent sized electric motor and chosen battery.

Thread: Differential thrust mix.
25/07/2019 13:46:20
Posted by Jon - Laser Engines on 25/07/2019 13:39:55:

I wouldnt recommend mixing throttles like that. I have owned 5 twins plus a 4 engine Hercules and have always set them up with y leads. All of the models were i/c, all of the props rotated the same way, all of them were easy to fly and taxi without any torque issues.

Dont make your life complicated, use a y lead

Very useful on twin engined water planes though.

One other option would be to add a V tail mixer and feed that from throttle and a spare channel, you could then mix rudder into the spare channel so you can set the differential throttle mix (you don't want a lot of differential throttle).

Thread: Variometer?
25/07/2019 12:36:42

Used to be quite common before telemetry, look up Picolario. There's one for sale on scalesoaring.co.uk at the moment.

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