siddus74

Hi guys,


Can anyone give me any advice on how to setup the retract / door sequencing? I have the two valves to operate them etc. Do I require additional components to ensure the doors open first the wheels down for landing and wheels up first then doors on take off etc? (Not something Ive had to do before ... can this be done on the radio? How are you guys achieveing this?

Best regards,

Scott.

Dave Wilshere

Scott

OK, you need to give us more info!
What model? Do main and nose doors go together? Do you want doors close gear up and down...can this work?
What valves, radio etc

Dave

madmodelman

You need a sequencer, the gear channel obviously operates the gear via rx input, the sequencer then operates your door valve for you automatically and timed, therefore all done only using one channel.
I like the Jet-tronic one best.
You could use two channels but you would have to operate them manually and that's too much to think about when you are flying.

Geoff White

Not strictly true Gary.

My Hunter uses two channels to sequence the doors and gear and it is all done using the TX, which in my case is a Futaba 14mz. But the sequencing can also be done using other high end TX's such as JR DSX12 or Futaba 12 FZ and, of course, the new 18mz.

To answer the original question there are basically three different ways to achieve the sequencing

1. Mechanically, I have a BVM Super Bandit and the gear doors are sequenced using a clever mechanical setup that utilises 2 valves, one for the gear and another for the doors. This method only uses one channel.
2. Sequencer. This is way Gary was referring to and the sequencing is done using a sequencer. Only one channel is used. The Jettronic unit is popular but there are others such as the relatively new units that are sequencer/valves/failsafe all in one unit.
3. TX Sequencing. This is becoming popular as you don't need any extra electonics in the model. The disadvantage is that it uses two channels but as you can have radios with 12-18 channels then thats not an issue these days. Of ocuse thinking about it, another disadvantage is that if you don't own a TX that can do this then is a bloody expensive to upgrade!

As Dave said, Tell us what you're trying to achieve, what radio you are using and then we can suggest a way of acheiving your end game.

Geoff.

madmodelman

Yes, sorry Geoff, my bad as I only use a DSX9 which doesn't have that facility, that's my excuse anyway!

Geoff White

No worries Gary.

DominicM

I use Spektrum radio gear and had no luck with the Jet-tronic sequencer. SM Services sequencer works best for me.

Rich_C

Hi,
I had this same issue a couple of years ago with my Tam F-16, only having the DSX9 I had to figure out how to handle the door sequencing, and I didn’t want to buy a sequencer as I had spare channels. My solution was to use two separate channels from the TX, one for each valve, and to use the servo slow function to give me the delay, with the DSX9 you can set the servo slow to different speeds in each direction. So with the valves connected to the servos so that they only operated at the ends of the servo travel (see the picture below for how I did it) I had the servo speeds set so that when I selected up, the retract valve moved immediately and pulled he wheels up, wheras the door valve was moved slowly and didn’t close the doors for a few seconds (or whatever you set) and when I selected down the doors opened immediately as the servo was set for full speed in this direction, and the retract servo moved slowly so the gear came down a second or so later. Of course on my viper now I just used an EVU5 unit which does everything for you.



Rich.

Greg Wright

My Feedback: (6)

I have done it the same way rich has suggested with my 12x on a p-47 thunderbolt. But for my BVM F-100 and F-86 i have used this sequencer from jet central to do everything for me as both of these planes need the inner gear doors to be closed when the gear are in the up and down position. This is a very nice unit as it also has a low air fail safe built into it and it will also handle running straight 7.2 volt thru it as i have all high voltage 8911 servos thru out my F-100 i didn't have to put a regulator in the plane and the system has been flawless.

KC36330

if it's as simple as doors open, gear out.........gear in, doors closed (F-16 as an example), you don't need a sequencer or a fancy radio with delay, a trigger valve on one of the gear legs works great.

FenderBean

+1 trigger/button valve is the way to go for doors that dont require some kind of closing once gear is down. I use this setup on canopy lock function and seriously considering adding it to my gear doors. I can drop down to just a UP-6 valve for brakes and nothing else. saves lots of money and some weight. [:-]

siddus74

mmm, this sounds like a bit of me ... can you provide a link to an example by any chance?

Thanks for all the replys

Scott.

Dave Wilshere

UP 2 or UP 3...brilliant and simple!

Dw

FenderBean

I have diagrams in my f-16 build thread for this very thing

Jgwright

Scott

The RCbee sequencer is simple small and light and works well. I have had 4 of them and I have just ordered my 5th.

The sequencer can cope with doors that have to close when the gear is down.

John

cmjets

Hello:

This system is like told Geoff, 1 - mechanically ...

With the BVM button valve, if you no need clse the doors with gear down !!! I have this system in my F-18 and had it in the Bandit.

http://shopbvmjets.com/zencart/index...roducts_id=104

BR from Spain.

Carlos Márquez.
_____________________________
http://www.cmjets.blogspot.com/

Airplanes400

My Feedback: (349)

I use an EMS gear & door sequencer. Just $38 at Tower Hobbies. It can be setup for gear doors that remain open when the gear is down, or setup for doors that also close after the gear is down. It also has an adjustable delay between door and gear deployment. Been using these for years. Never had a problem, and each one I buy saves me at least $70 over any other brand sold by the jet companies.

Made for Futaba as well as JR.
For JR ...
http://www3.towerhobbies.com/cgi-bin...?&I=LXCJE1&P=7

For Futaba ...
http://www3.towerhobbies.com/cgi-bin...?&I=LXCJE0&P=7


Good news for you, siddus74, Tower Hobbies ships internationally.

sledge_78

My Feedback: (24)

Skidus,

I have a Top Flite P-39 with Robart Air retracts. The front gear door operates as part of the air system. Robart makes a air cylider you can use for the gear doors. they show how to connect the air lines so the door opens before the gear trys to lower and closes after the gear is retracted. It seems to work fine. I hope this is what you are referring to. I don't have a separate valve for operating te gear door/s. I just connected it via the Robart instructions. Check their web page I think you will find it.

Sledge_78

Ruizmilton

My Feedback: (29)

The button switch valve method is not always a good idea, be aware that during the period you select up retracts and the the moment the button valve is triggered, there is no air pressure holding the door open, if your model is one such that the airstream will close or move the gear door with no air pressure, you risk the door getting caugth on the rising strut and then have a failed retraction...it works for the F-16 ( I used the method) but not on every model.

KC36330

Sorry tried to post the reply from my phone and hit edit by mistake.....

Ruizmilton

My Feedback: (29)

Maybe I did it wrong, could you post a diagram?

Thanks

Eaglepilot2

I've been reading this with interest. I have an f-16 that I'm having the same question with. I understand how the valve is triggered by a strut striking the valve. But explain how the doors open when you select gear down. Does the gear push the doors open??

KC36330

Air from gear down is applied to
The door rams and that opens the doors and drops the
Gear

essyou35

My Feedback: (11)

I had considered buidling my own sequencer using an arduino as I also have a functional canopy with locks on it. So I would need two sequencers. I could build it for about $20. However given the cheap options in this thread probably just get something tried and true, if they are in fact proven to work well.

The arduino could be hooked into a a tranducer to monitor air pressure, and the gears could hit switches to monitor status, so I could turn a light on the air craft when I have "3 green". but the cost quickly approaches $100 to custom build it with all that functionality.

One thing is for sure, gears not functioning will ruin your day so make sure you get something proven.

Right now my soltion is a 3 way switch. So as I move through the positions the doors and gears go in sequence down and back up.


To the gentleman talking about slowing servos down. I tought about this, but what Ifound is as the servo moved the valve from on to off there was considerable air loss between states.

KC36330

you've got a bad valve then. i've never had a valve leak air anywhere in it's normal travel range. i even used one on my Tornado with spring air retracts, with air on the gear side, gear comes up, valve to mid position, gear down, valve to opposite side, brakes applied, it's sat for weeks and still has air in the system.