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Member postings for Chris Walby

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

Thread: Forum members' new models: Let's see them.
19/01/2020 14:18:50

Hot on the heels of Trevor's canard is my take on the Can Doo although I went more for the drone/missile look at this stage. The pilot can be added to the top battery hatch at a later stage.

My better half practiced her covering skills in readiness for covering her Ohmen although I did point out curves are a magnitude harder than flat surfaces, she seem more adept than me.

Made from bits lying around and things from the naughty corner, it was an easy build.

20200119_104837.jpg

Maiden was lively, but once I stopped over controlling it and trimmed the excessive up elevator out it was quite pleasant.

Second and third flight had me dialled in with rolls, loops (very nice!) and slow low passes easy to do.

Do's and don'ts

  • Don't hand launch very nose up
  • Do loops with plenty of power through the top....or it will fall out blush
  • Hand launch under arm near horizontal and it doesn't tend to roll
  • Very slow and you run out of elevator, but easily recovered with throttle
  • Fly inverted..hardly any drop out or corrective action required

Overall a nice in the back or the car anytime model running on 3S2200.

PS should confuse the Scouts for a bit while they work out which direction it should be flying

Edited By Chris Walby on 19/01/2020 14:20:45

Thread: When to Maiden your first new build?
12/01/2020 11:22:20

Option 2, but with the cowl and all major parts fitted.

No problem with electric as the model will stay oil free and the detailing/paint will not add that much weight or change the balance, but always worth checking the CofG if things are changed.

I have a IC model that I intend to do the above and will just have to de-oil for the final painting as this has two benefits

  1. I can pick a primer paint scheme that is far easier to see than a leopard pattern for the maiden
  2. I can add the final detail and colour scheme once I have found out if is old and very infrequently used plan set flies or not.

    This is my first change in scale, very modified and complicated build for me.

I am reminded of a club member you spent hundreds if not thousands of hours only to loose the model on the maiden. The quality of build and finishing was way better than I could ever hope to achieve and at that point I thought I would build and fly, then finish/detail at a later stage. Of course this is not necessary if the design is well proven and its just easier to cover it the once up to finish state.

PS - I was reminded at our club where a model was test flown but had engine issues so the cowl was removed, engine problem resolved the next flight was carried out without the cowl. Only problem was the quite significant weight to get C of G was in the cowl....how does the motto go?

I agree with Paul, if you fly it without the cowl and get it all nicely trimmed in, would fitting the cowl then need it trimmed in all again?

 

Edited By Chris Walby on 12/01/2020 11:24:34

Thread: Do you remove your lipo from your transmitter every time?.
09/01/2020 12:44:48

My experience is my non lipo TX is frequently on charge and takes forever to get to near 100% where as my lipo Tx will last longer and charge quicker with the lipo it came with.

PS My lipo TX will charge on a wider input voltage range and won't over charge the cells.

Thread: ESC overheating.
08/01/2020 13:50:22

work is work, if you are driving a prop at increasingly higher speeds (within reason) then it must by the laws of physics consuming more power.

The twist to this is how stressed and efficient the ESC is at various speed settings. As Dick has eluded to, at lower speeds the instantaneous current through the FET's might be higher thus placing more stress on the FET device + it will be less efficient and produce proportionally more heat. This might explain why ESC's tend to fail (if not overloaded) at lower speed settings and why they get warmer.

At WOT and increased airspeed there will be more air passing over the ESC (assuming its ventilated) to cool the additional heat generated hence the combined effect of lower air flow and lower ESC efficiency places the ESC under greater stress when at low throttle settings. Does that sound logical Spock?

Thread: Propeller alternative chart
08/01/2020 13:19:30

I don't think there is due to there being to many other variables to consider.

The two on pitch to one on diameter (or 1 to 1) seems a good rule of thumb e.g. 12x6 or 11x8 works out although considerations for high pitch props is a factor in overall flight performance

Alternatively there are some good motor calculators on the web that take account of the many factors that need to be considered.

Me, prop to suitable ground clearance, watt meter to determine pitch with a small safety factor and away you go. If you have a need for speed then start with a high pitch prop and determine the diameter.

Thread: Max Thrust Riot versus Wot4
08/01/2020 13:06:52

Keith, I think you are missing the point completely.

Go back to day one and ask yourself what you would like to see in your first trainer.

Stable, slow, robust, forgiving and low cost

People seem to read into a name far too much, one of the US reviews absolutely slated the RIOT for its lack of aerobatic performance and ability to do unlimited verticals.

If it serves the need of the complete beginner and then provides a bit of fun beyond that then its totally achieved its goal. By all means modify it if you wish, but it will always be a RIOT (high wing slab sided trainer). By all means keep it as a winter hack or try out different TX settings, but once its got you through your A then its job is done. Time to buy a model that will challenge you further and unlimited verticals if you want.

PS Although capable and within the weight limit, in my opinion its not appropriate for the B test.

Thread: ESM Tigercat - powered by Laser engines
04/01/2020 21:22:48

Ron,

My calculations could be wrong, but at a typical flying speed without the prop wash effect you'll be pushing 128 litres per second into the cowl (that's a lot or air per second in my book!). Forming a baffle to direct the incoming air over engines would reduce total frontal area, but increase the in/exit area ratio.

As Jon mentions I don't think the total area is important, rather directing the air in the right direction and allowing it to exit the cowl is more important.

PS What fuel are you using and % nitro?

Regards

Thread: Phone APP for RPM reading.
04/01/2020 20:46:32

Robin, Motorcycle then sitting astride would be acceptable and walking up with a can would result in non recognition of the NPR system and authorisation by the attendant who would visually ensure you were not operating your phone

Steve J, My understanding is that your are wrong as zone two extends to near the roof line of a typical car.

p station.jpg

04/01/2020 13:18:39

Peter,

I asked a garage attendant about using a mobile phone in a potentially explosive atmosphere and they were quite clear that the phone is to be used to read the pump code while inside the vehicle. Hope that clarifies the position on the use of potential sources of energy within this type of hazardous area (I have a CompEx qualification for Hazardous areas), but like the USA no system if fool proof to the ingenious fool.

As for the tacho, I agree that a suitable tool for the purpose is best for fault finding although Jon's method works for 99% of the time for me. wink

Thread: Very heavy drones!
02/01/2020 21:01:51

I think 250kg is quite reasonable.

The Queen Bee RC 1:1 scale came out at 828Kg, now I really think you should have proof of purchase and your CAA number attached !

**LINK**

PS I know someone who has one although he prefers to be in it when flying laugh

Edited By Chris Walby on 02/01/2020 21:04:00

Thread: ESM Tigercat - powered by Laser engines
02/01/2020 08:10:33

Still following like an excited schoolboy!

Don't forget you are running maximum cooling with no cowls.

A few days ago I was flying the 180 laser Yak and it took an extended time to warm up, needed to be a bit richer at WOT and I just kept it away from WOT during the flights critical stages.

What was surprising was a friend checked the cylinder head temp with his hand just after flight (very short walk from flight line to bench) and remarked it was "cold" so with a lot of ventilation cooling off will occur very quickly.

I know its a bind, but I would do the final run up and checks with the cowls on (as that's the way it will be flown, but that's just me). I know there are lots of discussions about cooling and Jon surprised me recently with my twin with large cowls when he advised to just blank 80% of the cowl and baffle /direct air around the cylinders. I can see the point to cool the engine adequately, but the trade off with the cowls removed its they will go cold very quickly in these winter conditions.

Hope this helps in some way,

29/12/2019 21:29:43

Nice trailer setup there Ron.

How close are the props to the ground? Its only I noticed with George's electric (14x10) I am sure you can hear it trimming the grass (grass as tall/longer than the height the wheels) and my Dual Ace has a very springy nose wheel so if I make a poor landing it can just touch a prop.

Surprised it took 170g to get C of G, but then again my mossie has everything as far forward and some brass prop nuts..

Good luck, good preparation and as Jon says always have a plan B in mind and I am sure the maiden will be okay.

Don't forget to get someone to video it...the sound alone will be something special.

PS what's a 160 V weigh anyway?

Edited By Chris Walby on 29/12/2019 22:07:37

Thread: Members Map
29/12/2019 10:15:50

Martin,

It does show your location...Cockernhoe….perhaps you were in free flight mode that day!

PS rough location is okay with me, I would rather not have something like Google or another looking through my front window all be it I am probably been tracked by my phone anyway...now I wonder where I left that?

Thread: Cambrian ME109 Funfighter electric build
28/12/2019 07:12:43

Hi Martin,

I had one of these three years ago, nice kit with most of the bits need for the build. My idea was to gain some building experience with a quick build and a model that didn't need any field assembly. There was another motive and that was to have something that was fast to practice with.

I had a load of 3S2200 lipos left over from the high wing foam model so that's where I started on the search for more speed.

From memory

  • Fit a rudder servo as I did an intro pylon day (great fun at BMFA Buckminister), but you can't knife edge it without!
  • Under hand launch at 3/4 throttle and get on top of the torque roll...beef up motor mount and make the cowl removable ahs it helps when fixing the motor mount!
  • PVA wing bandage and pull insane tight turns and they never clapped, in fact when it finally crashed for the last time the wing is still complete

Summary

  • Nice build, but thick wing profile so nice and tame but has high drag
  • Couple of errors in the instructions, but photos very helpful
  • If you want fast this is not the model, I wound it up to 381 W/Kg and it just demonstrated that massive power does not overcome high drag
  • I would try the other funfighter manufacturer next time

All the best with your build and keep posting progress

Are you intending to go 3S or 4S setup?

Thread: Funny caption ideas?
26/12/2019 21:34:18

How many times do I have to tell you Cliff "fly into wind when you land and the pot of modelling gold will be on the starboard side, just like this"

Thread: Thank You SLEC great service!
26/12/2019 06:28:45

Top marks to the SLEC team, ordered some balsa Sunday night and delivered Tuesday PM. Okay not the most economic way, but good quality and it made it through the Christmas parcel chaos. Well packed and no damage.

Seasonal Greetings and well done SLEC Team

Thread: Hobbyking
23/12/2019 20:22:22

What drives me nuts is the auto refresh function which is okay if you have a fast device/speedy connection, but so frustrating I give up more often than not. Too clever for its own good.

And don't get me on import duty, if you miss one item that's not from EU/UK warehouses crying

Thread: TN Concorde
23/12/2019 18:53:40

Hi, I had a TN Ta154 that I thought I would try out some digital servos and a HK UBEC and was doing some bench testing so the servos were unloaded.

I was messing around with mixing rudder to throttle and had the 3S2200, UBEC, RX and aileron (2) and elevator servos attached when I noticed something odd with the RX.

Everything worked ok until I buried the sticks in the corners of the TX (like I might if recovering from something quite unpleasant!) and the RX would flash indicating it had lost signal. With multimeter in hand I discovered that the UBEC voltage would collapse due to the servos inrush current. Never had the issue with analogue servos especially unloaded

Might be worth ensuring your BEC is up to the job of full demand before flight.

Thread: DB Hurricane paint and finish.
23/12/2019 12:47:55

I agree with Don, as the original was mostly likely never one scheme for any length of time and just got patched and painted with whatever came to hand, so just pick a photo and base it on that, who's to say you are wrong.

PS Nice colour scheme, should be near impossible to see in the winter afternoon sky....Only the howl from the V twin will give anyone a clue you are coming in for a low pass!

Thread: Field Box
19/12/2019 15:17:29

Hi,

A personal cautionary experience as I used to use a puffy lipo on my starter. Used it for weeks and weeks and then it seemed a bit dull, checked it and popped it on charge in the clubhouse as I was the only one there.

Nice day so the clubhouse door was open and after a couple more flights I returned back to make tea and check the lipo.

Odd smell and a very very puffy lipo that had vented one cell on the table. Disconnected and moved to the non combustible concrete outside for disposal.

Too things

  1. Be very careful charging puffy lipos even if they are no longer used for models
  2. Best not to leave your lipo in the starter if you store it in your flight box or near the fuel for obvious reasons

Hope this helps

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