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

[Mitchell Howard]

Hi - I'm close to taking my A test following some tutelage at my club, enjoying it all very much!

 

One thing (amongst others) I need to lay my hands on is these posts that the horizontal tailplane would run into to prevent the model from running away. The search terms I've tried aren't doing anything for me.

 

I have an electric model, but it seems like the general school of thought is that they should ideally be used for both IC and electric models.

[Bob Cotsford]

like this? It's called a restraint.

[Mitchell Howard]

Wonderful thanks Bob!

[MattyB]

You can make your own very easily using whatever you have to hand; PVC pipe from any DIY place wrapped with some foam insulation and mated to an old screwdriver or stake works well. Personally I prefer the simplest, lightest solution - a loop that goes over the vertical fin and under both horizontal tailplanes anchored to a stake behind the model. I do only fly relatively small electric models though, so can appreciate you might want a more traditional "Y" shaped restraint for IC models where you are in front of the prop during starting.

[Ron Gray]

A couple of straps around the wings for larger models:

[GrumpyGnome]

That's interesting Ron. How do you 'release' the plane?

[Ron Gray]

Engine on tickover, pull it back to loosen the straps then slip them off over the wing tips. Shown here in the vid (2.35 into the vid) that the screen shot was taken from (in this vid my buddy held the tail whilst I slipped the straps off). Has the advantage of restraining the model by something arguably stronger than the tail!

 

 

Edited May 7, 2021 by Ron Gray

[John Muir]

I'd really struggle to push the screwdriver into the tarmac!

[Andy48]

3 hours ago, Mitchell Howard said:

Hi - I'm close to taking my A test following some tutelage at my club, enjoying it all very much!

 

One thing (amongst others) I need to lay my hands on is these posts that the horizontal tailplane would run into to prevent the model from running away. The search terms I've tried aren't doing anything for me.

 

I have an electric model, but it seems like the general school of thought is that they should ideally be used for both IC and electric models.

With electric, I don't use a restraint as I do not "arm" the plane until it is on the field ready to take off. Mine are all armed with an arming plug in the side of each model. This effectively acts as a switch which switches off the battery. I use a shorted XT60 as the arming plug for most, you cannot use an ordinary switch for this. Its almost foolproof. This is pretty much the method used in the BMFA A test video, although they connect the battery on the flight line whereas I usually use an arming plug as often the battery is not always easily accessible.

 

 

Edited May 7, 2021 by Andy48

[Ron Gray]

Interesting that you don't use a restraint Andy, how do you do the failsafe test and also test for control movement with engine running?

[Don Fry]

1 hour ago, John Muir said:

I'd really struggle to push the screwdriver into the tarmac!

4 lb Birmingham screwdriver, to provide the push?

[Ron Gray]

1 hour ago, John Muir said:

I'd really struggle to push the screwdriver into the tarmac!

Takes years of practice John and lots of blisters! but the Brummy screwdriver is a useful tool to assist!

[MattyB]

22 minutes ago, Ron Gray said:

Interesting that you don't use a restraint Andy, how do you do the failsafe test and also test for control movement with engine running?

 

Popcorn at the ready... ??

 

To be fair for the A test you can technically restrain your model using the old "legs in front of the tailplane" method, though I'm not sure many of us could actually install and connect the battery from that position! 

Edited May 7, 2021 by MattyB

[Andy48]

47 minutes ago, Ron Gray said:

Interesting that you don't use a restraint Andy, how do you do the failsafe test and also test for control movement with engine running?

Failsafe as in the BMFA test, as Matty B says legs in front of tailplane, though to be honest transmitter won't respond without failsafe set, and I also get a verbal warning. Don't see the problem with control movement, the plane is already on the runway ready to take off. Frankly with electric does the engine have to be running to check control movement, and if so can someone explain the rationale behind it.

 

[Frank Skilbeck]

When you do a range check, you should do it with the motor running to make sure it isn't reducing the range etc. Also to demonstrate correct failsafe operation then you need to have the motor running and then switch off the Tx (and show the motor stopping on loss of signal).

 

I have been asked to test fly new models at the club and always do a pre-flight range and failsafe test, quite a few didn't have a correctly set failsafe. Note also that different makes often have different methods of setting the failsafe, so if you are on brand A, don't assume that brand B has the same failsafe setting procedure.

[Ron Gray]

As Frank says, motor needs to be running for failsafe. As for feet in front of tail, as the A and B have a large content based around safety is that really the safest way to restrain a model? (but we have all done it!)

 

Maybe straying a bit off topic now?

[MattyB]

9 minutes ago, Andy48 said:

Failsafe as in the BMFA test, as Matty B says legs in front of tailplane, though to be honest transmitter won't respond without failsafe set, and I also get a verbal warning. Don't see the problem with control movement, the plane is already on the runway ready to take off. Frankly with electric does the engine have to be running to check control movement, and if so can someone explain the rationale behind it.

 

Back in the days of brushed motors and 35MHz you could see quite significant dips in range between motor on/off, but despite doing this test on all new models I've never seen that same effect on 2.4GHz. Happy to be corrected, but I suspect it is no longer a factor if you have spread spectrum radio. They certainly couldn't remove it from the BMFA handbook as there is still plenty of people using FM.

[Dwain Dibley.]

My method of restraint.  Zenoah 45.

D.D.

 

[Don Fry]

Arrrrrrrrrrrrrrrr, Matty. But the point is, is the setup stable, throttle on or off. It’s got nothing to do with if the problem is vibration, or electronic.

If it leaves the ground, it has to be landed. It has to be checked.

[Andy48]

1 hour ago, Frank Skilbeck said:

When you do a range check, you should do it with the motor running to make sure it isn't reducing the range etc. Also to demonstrate correct failsafe operation then you need to have the motor running and then switch off the Tx (and show the motor stopping on loss of signal).

 

I have been asked to test fly new models at the club and always do a pre-flight range and failsafe test, quite a few didn't have a correctly set failsafe. Note also that different makes often have different methods of setting the failsafe, so if you are on brand A, don't assume that brand B has the same failsafe setting procedure.

Sorry, but I disagree about having the motor running for range test.  I have telemetry on my system so on every flight I have verbal warnings long before the model goes out of range, and on a new model I check the telemetry after a couple of test flights to ensure all is well. This is a far more comprehensive test for the range test, and yes I am well aware the motor has to be running to test the failsafe.

 

Newer systems with far enhanced capabilities need a rethink of 70s approach to such things as this.

 

Edited May 7, 2021 by Andy48

[Don Fry]

I too have telemetry. Great improvement, to fine tune a system in the air. 
But it still does not replace the best effort you can make, in all the conditions you can apply, to test a system on the ground, before it leaves the ground.

I accept, if you have telemetry, rather than a range check, you can simply look at the data, as you walk round the thing, but you have to test motor on and off. 

[Frank Skilbeck]

Yep, I too have telemetry and it alarms if the signal quality drops, but I still do a preflight range check on a new model. Not every set has signal quality feedback or alarms, and even if it does not everybody knows how to set it.

 

Anyway getting back to a field restraint on an electric model, also useful if you are doing and electronic adjustments between flights.

[john stones 1 - Moderator]

Now now lads, let's be having no divergance on the test standards, be sending you to workshops. ?

[Gary Manuel]

I have test flown models for other people a number of times. On at least two occasions, when I have done the fail-safe test the engine has revved up to full throttle rather than cutting. Thank goodness for model restraints is all I can say!

 

The cause of this was a simple mistake. Binding with the throttle channel initially reversed, then reversing the channel to correct it, but failing to rebind in order to reset the failsafe.

 

On the other hand, I once almost had a very nasty accident due to use of a large version of the type of restraint linked in the second post. I had been doing some work on the tail wheel of "Dusty" as per my Avatar image, with the tailplane resting on top of the restraint to allow the tail wheel to dangle in mid air. Some time later, it was time to have a fly, so I flicked the DLE55 into life, the model moved slowly forwards, but instead of being restrained, the tail dropped off the restraint. The spinning propeller was now heading directly towards me! I managed to jump backwards without instinctively putting my hand in the prop and finished up in a sitting position with the propeller heading towards my meat and two veg! I managed to get one foot onto one wing's leading edge and the other foot on the other. My manhood was safe but there was a problem. I couldn't quite reach the transmitter because I had jumped backwards away from it.  All I could do was shout for a fellow modeller to pass me my tranny (or wait for it to run out of fuel), so that I could hit the kill switch. A day I wont forget I can tell you.

Edited May 7, 2021 by Gary Manuel
Typo corrected

[Andy48]

37 minutes ago, Don Fry said:

I too have telemetry. Great improvement, to fine tune a system in the air. 
But it still does not replace the best effort you can make, in all the conditions you can apply, to test a system on the ground, before it leaves the ground.

I accept, if you have telemetry, rather than a range check, you can simply look at the data, as you walk round the thing, but you have to test motor on and off. 

Again I disagree. After doing a range test with a new model on the ground (engine not running), what can be better than examining the telemetry of a new model after a few test flights in the air. A ground test is just that. As I say, I get immediate telemetry warnings anyway, so what is the point of doing a range test on the ground with the motor running? It simply isn't needed. Add to that a range test for me is walking to the edge of our field, a distance of 130 metres, and it is still in range.