AEROTECH I205

[n3tjm]

Bought one of these to fly in a LOC Vulcanite. Figured I share some pics cause I couldn’t find any.

 

[n3tjm]

Inside the little bag isthe igniter, ejection charge, washer, and ejection cap.

 

[n3tjm]

29mm diameter and 330mm long (12”). It has quite a heft to it.

 

[n3tjm]

I was curious if it uses the same nozzle as an I200 RMS. I don’t have an I200 to compare it too.

 

[n3tjm]

The ejection charge well. You insert the washer before the ejection charge because the touch hole has to be enlarged for the universal delay adjustment tool. The enlarge hole without the washer weakens the ejection charge.

 

[Cameron Anderson]

This motor screams. I took it for granted because it's 29mm and was expecting G level performance. Nope! Don't blink when you launch it or you'll miss it.

 

[Rocketjunkie]

If you don't put the washer in before the BP, the ejection will go out the nozzle. The same nozzle is used for the I200.

 

[Cameron Anderson]

If you don't put the washer in before the BP, the ejection will go out the nozzle. The same nozzle is used for the I200.

Is that what the washer is for?

 

[ChicagoDave]

Love the I205 - I fly one practically every launch. That or it's baby brother the I200. I never fail to get a "WOW!" out of the crowd. Last time the rocket pulled 30.5g's max acceleration.

As mentioned already put the metal washer in first, the the ejection charge. Otherwise you'll have a ballistic on your hands.

 

[Cameron Anderson]

I always fly electronic deployment so I don't load my motor ejection charges...but the mechanics of how the washer functions doesn't make sense to me.

 

[ChicagoDave]

I always fly electronic deployment so I don't load my motor ejection charges...but the mechanics of how the washer functions doesn't make sense to me.

The problem is that once the motor is spent and the delay grain has burned there is nothing preventing the ejection charge from falling back out through the casing and out the nozzle. When the ejection charge goes off this becomes the path of least resistance and the charge blows back out the nozzle..

This is because the DMS motors (unlike the RMS) must have a hole big enough to pass the UMT drill bit through in order to trim the delay grain. The metal washer contains the delay grain and permits just enough flame to reach the main part of the charge, and restricts the pressure backflow so the ejection goes fore, not aft.

~Dave~

 

[Cameron Anderson]

The problem is that once the motor is spent and the delay grain has burned there is nothing preventing the ejection charge from falling back out through the casing and out the nozzle. When the ejection charge goes off this becomes the path of least resistance and the charge blows back out the nozzle..

This is because the DMS motors (unlike the RMS) must have a hole big enough to pass the UMT drill bit through in order to trim the delay grain. The metal washer contains the delay grain and permits just enough flame to reach the main part of the charge, and restricts the pressure backflow so the ejection goes fore, not aft.

~Dave~

Is the inner diameter of the washer smaller than the forward closure hole? I recall it being larger.

 

[crossfire]

Just use the washer. I flew a early K535 with no washer. BP sucked out the nozzle. Tape I put over ejection well was still on after the flight.

 

[Cameron Anderson]

Just use the washer. I flew a early K535 with no washer. BP sucked out the nozzle. Tape I put over ejection well was still on after the flight.

I haven't used motor ejection one single time since 2007 when I got my first DD altimeter; the mechanics of this washer fascinates me now.