Peter Jenkins

2025-03-21T10:22:09Z

Nutters, flying that close to themselves at that speed!

March 13

Just one more point Birgir, if you are taking off in a cross wind, as soon as the aircraft starts to move, and sometimes before if its a strong wind, the model will act like a weather cock and the fin/rudder will yaw the aircraft into wind. If you had a wind coming from the left when you take off then that will also have added to the yaw to the left.

I always think to myself before I start the take off, which way will the wind swing the aircraft so which rudder to apply, left or right? On a strong wind day, you might start with rudder deflected, in the correct direction, before you apply power and then adjust with the rudder to keep the aircraft straight. Remember also that applying, say, right rudder will also cause the aircraft to roll to the right as airspeed rises so be prepared for a touch of opposite aileron to the rudder to keep the wings level - it won't be much aileron but it might stop the wing being tipped over. Also at no/low speed, especially for a high wing model, the wind can "get under" the wing and blow the model over as well. So, thinking about what the aircraft can do before you apply power will help to prevent situations like this occurring. Also, if you need to land on a runway as opposed to into wind, the cross wind take off will help you to remember that on approach the aircraft's track should be along the runway heading but the aircraft's heading will be to the windward side of the runway. As you round out to land, you will need to squeeze on enough rudder to align the aircraft's axis with the runway and the direction to move the rudder will be the same as you used for take off. Again, be ready for some opposite aileron to prevent a roll in the direction you have applied rudder.

There is a lot going on when taking off and landing and indeed flying a good circuit to give a good stabilised approach path is the precursor to a good landing.

March 11

Hi Colin, quite understand. It's a shame you don't have the space to fly a schedule. I think Miss Wind is an earlier design compared with the Axiome 70 bipe. I've been flying designs from BJ Craft and each new model has benefitted from lessons learned and design changes. I started with the Agenda, then Element and now Anthem. Each has been better by small but noticeable amounts than its predecessor. However, setting up and trimming play major roles as you no doubt know. There is a 70 size bipe offered by BJ Craft that will be a more advanced design than either the Axiom or Miss Wind. This is what it looks like: https://www.bondaero.co.uk/BJ_Encourage_70/p1085152_20098103.aspx#

I'm sure there will be second hand versions available at a more attractive price.

March 11

Do you fly in aerobatic competitions Colin?

Posted March 11 · March 11

Well done Simon. Look forward to seeing it in action at Knettishall.

March 10

12 minutes ago, John Lee said:

That may be because tab(s) fitted further outboard may tend to twist the wing, actually exacerbating the wash-in. I would expect that the structure inboard of the ailerons will be stiffer so better able to resist the twisting.

It is the same effect as the phenomenon of aileron reversal where a wing has insufficient stiffness and leads to control difficulties.

This reversal was more common in the early days of manned aviation but still needs to be guarded against today. Many airliners with their long floppy wings have inboard high speed ailerons as one of the measures to ensure controllability in all flight regimes.

John

A wing with low torsional stiffness is a disaster waiting to go into flutter. Avoid building such wings. The best way is to use a wing box arrangement i.e. a closed tube. All aeronautical structures are like closed tubes. You are right that in the early days of trying to break the sound barrier designers did not build sufficiently stiff structures. So you got control reversal which was just the effect you mention. Once they realised that, the structure was beefed up and it didn't recur. If you do have a model with a wing of very low torsional stiffness I would suggest you don't fly it as it could end in tears!

March 10

I'd put the trim tab on the warped panel to try and unwarp the effect. You don't want to add wash in on the other wing. Why? The way a wing stalls determines how it acts when it stalls. The correct stalling sequence, for non-aerobatic aircraft, is wing root and then tips. If the tips stall first, which is what wash in will induce i.e. the wing tip is at a higher angle of attack than the wing root, the wing tips will drop and the effect will be far more dramatic than a root stall first.

March 3

4 hours ago, Adrian Smith 1 said:

Day one of a sparkling week of weather 😀. I took the opportunity to test out a larger prop on the SW Edge. The 26x10 I have been using seems fine for the flight duration/performance I am aiming for. The motor's recommendations for 12s setup on the GA 8000 motor is either 26x10, 27x10 or 28x10. I was expecting more of a lipo drain on the larger prop of 27x10 and I wasn't surprised that for the same flight duration/aeros each cell was drained an extra 0.5 volt after checking at the end of each flight (four this morning) . I haven't checked the telemetry data yet but I expect there will be extra current draw during the flight at WOT too.

One thing I am puzzled about is that at the end of any inverted aero upon turning upright and reducing the throttle she tends to float upwards for a while. As the flight progresses she stabilises after a dab of down elevator (am I allowed to do that?) . She flies fine upright otherwise as I would expect at various throttle settings. I did check the elevator servos and surfaces, but didn't find anything untoward. Also the security of the power packs.

I have flown her for 2 hours since the maiden and this only seems to be recent phenomenon. I will check the thrust line on the motor when I get a moment in the workshop to see if there's anything there. Another flying day tomorrow hopefully. This weather certainly adds to the feeling of well being after the winter.

Try moving the CG forward a tad. Sounds like you are close to a neutral CG with your current set up.

February 26

Simon

Unfortunately, just having a single motor with a contra does not eliminate the torque effect. Yes, the propeller effects are cancelled out but the single motor still has a load to turn.

The Adverrun I currently use suffers from torque effect but the TRMC, with 2 motors independently driving the props does completely eliminate the torque effect.

What I have observed is that the prop effects are of a higher order of magnitude than the torque effect.

February 26

Thanks for the info Chris. That is heavy!

February 25

Hi Roy

Thanks for the information. I've attached a photo of the Debowski Twin Motor Contra Rotating (TMCR) powerplant. The motors have a kv of 120 so with a 10S pack had a max rpm of around 4,800 swinging a 23x20 props front and rear. The great attraction of this setup was with 2 outrunners cooling was good and there was no maintenance of belts or gears. You did need 2 ESCs though but I found that controlling them using a Y lead to connect them to the Rx was perfectly acceptable. If my memory serves me correctly they weighed in at around 600 g. Sadly, following a failure of the JR X-bus converter board that froze the elevator and rudder control on the aircraft, terra firma put an end to its flying days. I was going to point you at his website but when I looked he seems to have taken the TMCR off it. Whether that means he's stopped making it or is about to launch a new version I shall have to wait and see.

I have no idea how much the TMCR costs to make but they are selling, or were, for around £1,600 including the 2 ESCs, spinner and a toolkit. A good deal more than you spent if you exclude your time. I suspect if you include your time, depending on how you value it(!), you might be in excess of the TMCR acquisition cost!

These days, there seems to be a move away from epicyclic gearboxes towards a belt and direct drive gear drive and replacing in-runners with outrunners. Most continue to cost in the £1,000 to £1,500 range though. They do not take kindly to nose overs though! I'm currently using an Adverrun V1 that is a belt and pinion drive. The early Adverruns had straight cut gears but they were soon replaced by bevel teeth that made far less noise. In fact, most of the noise is generated by the props and they do sound almost like a well silenced four stroke.

February 24

As a mztter of interest, how much has it cost to make your contra excluding the cost of the props? Be good to knos the weight as well. Commercial units for F3A are between £1,000 to £1,300. Designed for 10S and produce up to 3,600 W at around 4,000 rpm and 22 to 23 inch props. Some have 3 blade props but thd majority run 2 bladers.

February 15

I have to say that I use the UnisensE telemetry module in all my electric powered aircraft on their first flights. Ground testing is not terribly helpful. As an example, the Hacker Q80 in my Citrin pulled 3,400 W at full throttle tethered on the ground. As the motor is rated at 2,800 W I closed the throttle pdq! In the air, only once did I see more than 2,800 W and most of the time I never saw more than 2,750 W.

February 14

Hi Adrian

On my F3A setup - 10S usually 5,000 mAh pack - the usual max current draw is between 80 - 84 amps with max power drawn between 2,800 W and 3,100 W. You are running 12S so I would expect that like for like current draw would be down by 20% for the same power - based on W = V x A. I would expect with the larger heavier airframe you would be back up to my sort of figures. My aircraft's AUW is a 5,150 g with the heaviest pack. What's your aircraft's AUW?

I once saw a current draw of 99A but that was with my larger prop set (23 in as opposed to 22 in) and with a different motor (the TMCR as opposed to the Adverrun I'm currently using) and that was obtained by slowing the aircraft down right after take off with a fresh pack and then pulling to the vertical with full power applied immediately i.e. with maximum loading on the prop. That produced a reading of 3,600 W and 99A.

February 10

Any fluid mechanic problem at sub sonic flows will show that the flow remains attached longer for a higher radius leading edge. Not as dramatic in liquids as it is in gases as boats don't sink if they "stall".

February 10

Hi Adrian

Remember, the Tx is a computer with a radio bolted on. So, as PDB says, if you plug it into your computer and open File Manager you will see the menu structure and can opdn the relevant folder- good chance it may be called Telemetry.

That's how it works with my Jeti Tx as well.

February 10

Ufortunately propstar, nothing is simple in aerodynamics! Hence the use of rules of thumb for things that are observed to work.

To answer the question you posed, the thin wing on an oldy model aircraft will stall first.

February 9

It's a conspiracy between the hardware and software manufacturers!

February 8

Shame about Wales but great for Italy.

The 2nd game was a cracker and well done to England for holding their nerve. The French made so many handling errors and gave away too many penalties. Sadly Marcus Smith had an off day for goal kicking but thankfully Fin Smith had a cracking 2nd half. Phew!

February 8

Thanks for the detailed explanation. I shall continue with Win 10 until I decide to upgrade my hardware.

February 8

Thanks GG and PDB. My only worry is that of security when W10 support ceases later this year. So I guess a hardware refresh might then be necessary. However, as I have the BT/EE security software installed will that be good enough to keep me safe?

February 7

Just tried to update to Win 11 and got this on both my PC and Laptop:

This PC currently does not meet Windows 11 system requirements:

The PC must support TPM 2.0

The PC must support Secure Boot
The processor isn’t supported for this version of Windows.

Can someone translate what this means please? Bottom line, can I upgrade something or is it better to buy a new set of hardware?

Thanks

Peter

February 7

Nice job.

February 7

14 hours ago, Dickw said:

Interesting! I am also with BT and have had emails from EE offering a new contract but have ignored them so far. I will continue to do so 😀.

My main current concern is the changeover of the connection to full fibre into the house next week. If it all still works after that 🤞l might do some research on EE contracts (then again I might just leave it and see what happens).

Dick

Just done the change and when I queried why there was a cheaper option on the BT website, I was told that was for full fibre customers as fibre was cheaper. Well, blow me down, I've always been told that fibre to the premises (FTTP) was more expensive!

I also got the up-sell to EE TV and their best deal package including Netflix. I decided to give it a try as I was old I could jump down to just the basic sport channel that gives access to Tennis, Rugby Union and Cricket. But I had to listen to this lady trying to help me for an hour and a half! Even then, I had to go online to find out exactly what I had signed up for!

February 3

2 hours ago, Chris Freeman 3 said:

Byron and I had great flying on Saturday morning, got to the field around 06:30, no wind and not that hot. When we left around 10 it was very hot at close to 30!

Flew the Spacewalker and had lots of fun trying to land without a bounce. The Tiger Moth was made for those conditions and we put many miles on the wheels with touch and go's. The Stick had the counter rotating unit on it and it was surprising noisy with lots of prop noise. the performance is very good so we need to transplant it into the MB5. The grass runways are looking great after the rain but are a lot of work to cut as we only have 2 normal push mowers not ride on ones.

Yes, the noise from an electric contra can sound like a well silenced 4 sroke. Which contra and ESC are you using?

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