Posts to stop the model flying away (restraints and safe practice)

[Andy48]

I remember the many weeks in school woodwork classes perfecting the perfect tent peg. ?

 

[Gary Manuel]

1 hour ago, Martin Harris - Moderator said:

I've clarified the thread title as the thread creep (which did relate to the use of restraints during range testing) will be useful to beginners - and the odd more experienced pilot too!

Who are you calling odd?

[Dickw]

30 minutes ago, Gary Manuel said:

Who are you calling odd?

Probably applies to most of us ?

Dick

[John Muir]

I had a very similar experience to Gary, but luckily it was 'just' an Irvine 53 in my model. I had to tip the model forward to get fuel out at the end of the day and when I dropped it back down the tailplane came to rest on top of the restraint rather than in it. I gave it a tug forward as I usually do and it felt fine, but it was only the tailplane struts that were catching on the restraint, so when I started the engine the plane got loose and made a lunge at me. I tried to stand up to get out of the way but my hand was out in front of me and the prop clipped two fingers on my right hand. I had to visit A&E and go back for a bit of plastic surgery to get the tips reattached. It was only the very ends so it could have been a lot worse.

These restraints work very well when used properly and I'd say they are extremely useful. But you do have to use them with care. A contributing factor to my accident was listening to someone who was chatting to me while I worked. I just don't do this now. If I'm working on an engine or plugging in a battery I wait until I am not distracted before I do anything risky. I'll even tell somebody to go away if need be. I'm a rude so and so.

[Dickw]

1 hour ago, MattyB said:

There’s no harm in a power on range test, some of us are just not convinced it really adds anything vs a power off test if you are using brushless power and 2.4Ghz with signal strength telemetry. Of course I will demonstrate it that way if flying at a new site to comply with any local rules, but don’t use that method normally as a) it’s tricky on your own with a model without an undercarriage which most of mine are, b) like Andy I have telemetry in every model, and c) I’ve never had an instance when a brushless setup controlled by spread spectrum radio showed reduced range power on.

.........................................

I am in complete agreement with that, with the added comment regarding point (a) that if you are handling a multi kW glider with ‘motor on a switch’ and a power system rating of only a few seconds at a time static then a power on range test is next to impossible.

 

To check the motor fail-safe on such a system I remove the prop which then needs a lower voltage battery being used to keep rpm within safe limits – I regard that as a workshop job.

 

The point I am making is that range checking and fail-safe checking probably needs be varied according to the characteristics of the model and radio system being used.

 

Dick

 

[Ron Gray]

There are always exceptions to the rules and common sense has got to come into play. For my 4m+ WS Leprechaun I got a friend to hold onto it so that I could do the failsafe and range check.

[Ron Gray]

2 hours ago, John Muir said:

I had a very similar experience to Gary, but luckily it was 'just' an Irvine 53 in my model. I had to tip the model forward to get fuel out at the end of the day and when I dropped it back down the tailplane came to rest on top of the restraint rather than in it. I gave it a tug forward as I usually do and it felt fine, but it was only the tailplane struts that were catching on the restraint, so when I started the engine the plane got loose and made a lunge at me.

Maybe mainplane restraints would be a more positive way of holding the model back plus less likely to be ‘missed’?

[John Muir]

These days we have useable starting tables at our field which solve the problem nicely. If it's quiet they're the ideal place to put a model for range testing too as they are safe and up off the ground. Mind you I'd still use a tail restraint happily enough. I put a bright ribbon across the uprights and over the tail when I use it these days as a 'memory jogger'. And, as they say, 'once bitten'.

[MattyB]

20 hours ago, Dickw said:

I am in complete agreement with that, with the added comment regarding point (a) that if you are handling a multi kW glider with ‘motor on a switch’ and a power system rating of only a few seconds at a time static then a power on range test is next to impossible.

 

 

Agreed, those are exactly the sort of model I fly regularly (warmliners and F5J models) and the low power on time and high power ratings mean they ar ejsut impractical to test this way without help. 

[Ron Gray]

You can always take the props off, as has already been mentioned - totes safe!

[Dickw]

58 minutes ago, Ron Gray said:

You can always take the props off, as has already been mentioned - totes safe!

Ron

With some of my models:-

If I take the prop off and run the motor it would exceed the safe operating rpm of the (expensive) motor and gearbox.

When I take the prop off to check motor fail-safe I run it on a much lower voltage battery to keep the rpm down to acceptable levels.

If I did that to do a "power on" range test it would be meaningless because I would be running in a totally different way to normal operating conditions.

 

Variations in model characteristics means you have to adapt range and fails-safe testing to suit - there is no "one size fits all".

 

Dick

[Ron Gray]

Dick, I too have some expensive (Hacker) motors and gearboxes so, like you, wouldn’t want to run them at high revs. As far as I know there is no requirement to run the motor over low revs so that is what I do. With my F5J which, whilst it has a throttle on button, the program I’m running on my TX (Jesper’s excellent SoarOTX) allows for throttle control as well. I’m not saying that my approach is the right one, but for me it is and is also used after first connecting the esc to check the motor rotation which is just as well as I always seem to connect it the wrong way to start with!

[Dickw]

Ron, If you have a system that works for you that is fine.

 

I have a separate model memory for such models which gives me proportional throttle control for some testing such as initial direction and ESC setup checks. I could have a throttle function on the "flying memory", but I don't to avoid risk of accidental selection in the heat of competitions. With 5kW+ on tap even part throttle is a risk.

I must admit mine is an unusual setup, but with a current in the region of 180 to 200 amps via a 135A ESC I am not keen on running part throttle for any length of time (i.e. more than a couple of seconds) and even full throttle is never more than about 3 seconds static. My motor is controlled by a spring-loaded switch.

 

Fail-safe checks are only done using the throttle-less "flying memory" as that is the relevant condition, and if I can't do a power on range test at full power then I don't see the point of it as it doesn't represent flying conditions. A quick blip of full power while logging the telemetry will tell me if there is a problem.

 

Dick

[Ron Gray]

Sounds good Dick.

[Romeo Whisky]

Here's a simple restrainer design which can be adapted for different size models.  A tent peg through the frame anchors it to the ground as shown.

 

[Phil McCavity]

38 minutes ago, Romeo Whisky said:

Here's a simple restrainer design which can be adapted for different size models.  A tent peg through the frame anchors it to the ground as shown.

 

Nice. I like that.

[John Stainforth]

I have a device called an Airopult, which restrains the plane from moving both forwards and backwards. This has vertical posts that go in front of the tailplane, to prevent forward movement, and smaller posts that go behind the undercarriage to prevent backward movement. When one is ready to go, with the engine running, one just presses that black foot pedal at the rear of the device and the vertical posts in front of the tailplane hinge forwards, releasing the plane. The small posts behind the undercarriage collapse forward as the plane moves forward. I fix the rear of the device to the ground with heavy duty steel tent pegs (see photo). The device works very well, but it was a little pricey. I am not sure whether it is still available. But I will continue to use mine on model flying fields that do not have restraining benches.

 

[Nigel R]

I had something almost identical to RW's for a good while.

 

But. Currently, I am using an old cheap folding workbench (https://www.diy.com/departments/foldable-folding-work-table-h-755mm/1362664_BQ.prd) on which the adjustable worktop is long since defunct and replaced with a simple piece of board, to which there are secure attachments for a pair of yokes on the top. It works as a cradle to assemble the model in, plus a restraint when starting up. I put my flight box on the lower legs to keep the whole thing steady. Keeps everything up and away from the ground, too.

 

SLEC make a fancy stand which does the same thing neater and more professionally:

https://www.slecuk.com/flight-mate-table-kit

 

 

[Andy48]

Nobody's mentioned the most obvious thing for testing failsafe with an electric model. Just remove the prop, and run the motor at a very slow speed. No restraint necessary. ?

 

[Ron Gray]

Look back up the thread Andy, mentioned yesterday!

[GrumpyGnome]

I must say that as I get older, the idea of a stand so I don't have to kneel down to assemble things is more appealing (by assemble, I even mean putting a LiPo in!).

 

Not sure I'd want to start an engine on a raised, portable stand though  I'd be nervous of it toppling over....... that is probably me being over-cautious - which may well also come with age!

 

GG

[leccyflyer]

Since first using start up tables, coming up to twenty years ago now, I find them marvellous. Two of my current clubs have start up tables and it's a joy to be able to make the final battery connection in comfort, with the model properly restrained at waist level.

 

Back in the day it meant scrabbling about on the floor, starting the model in the pits and then carrying the live, running model through the pit area -an accident waiting to happen. I used to have a restraint made from pipe fittings which held my IC models by the tail. It was a faff to take it to the field and it was used in the pits, which I considered far from ideal. The field set-up revamp, with cable drum tables for model assembly in the pits and proper start-up tables airside made a much safer, smoother operation. 

[GrumpyGnome]

@leccyflyerI can see that those could not tip over!  Sadly, we are not allowed fixed tables at our field...

[Bruce Collinson]

GG,

There is/was a thread a couple of years back about a model stand made from a Screwfix scaffold/trestle with minor modifications and I use one for fettling i/c setups and running in, because of the excellent access and in deference to my dodgy knees.   If I'm flying electric I use a leisure battery as an anchor, if not a corkscrew dog tether (the chrome plated ones penetrate better, less friction) and paracord as I too was nervous about the thrust from a Saito 125 .

 

A slight faff remembering first in the boot but a boon when doing jets, cowls, props/spinners etc.   So handy that I have one permanently in the Mancave; it has a large elastic band at the back to stop the tail lifting, whereas the flightline one has bungee straps with hooks, ribbon rather than cord.

 

BTC

[Romeo Whisky]

This is what I use for bench-testing models at home.  Our Club flying field has restrainer benches so there's no need to take one to the field.