Plugging Aerotech Reload

[sr205347d]

New to the forum, and first post. I have been doing RCRGs for about a year. This may be common knowledge, but I thought I would post something I learned the hard way.

I have been successfully flying my Dynasoar Rocketry Aurora Clipper (classic BT-80 version) with a variety of motors, including some requiring the 24/40 casing that needs to be plugged. My plug was just a bit of flameproof wadding in where the ejection charge would go.

It worked fine, until it didn't. On the last flight, the boost and glide were awesome! After landing though, I discovered that the delay element had burned through. There was not enough pressure to blow off the nose cone, but the hot gasses partially melted the depron motor mount pieces, forcing the retirement of the model.

I have since filled the ejection charge compartment with epoxy to prevent this from happening again.

Now, what to build to replace the AC? I like the large size, but Frank has downsized the AC. I may need to do a scratch build.

Andy

 

[rharshberger]

@burkefj , Frank might have a few ideas.

 

[sr205347d]

@burkefj , Frank might have a few ideas.

Would there be any problem using the RMS-R/C 24/20-40 casing (normally specified for the D7/E7/E6/E12 RC reloads) with E18 or F24 reloads?

 

[SolarYellow]

Would there be any problem using the RMS-R/C 24/20-40 casing (normally specified for the D7/E7/E6/E12 RC reloads) with E18 or F24 reloads?

Would be a good question for the

AeroTech Open Thread​

 

[burkefj]

Would there be any problem using the RMS-R/C 24/20-40 casing (normally specified for the D7/E7/E6/E12 RC reloads) with E18 or F24 reloads?

Yes, there is a problem using them as is, they need a forward solid insulator added to protect the aluminum front end of the plugged case from direct heat impingement, it sits inside of the liner and they have them on the rocketmotorparts site aerotech has, the one that comes with the reload has a hole for the delay and is no good in this usage. once you put it into the liner the propellent will stick back a bit toward the nozzle, it may or may not allow full closure seating, but due to the cone shape of the nozzle interior they usually will, I've run F-24 motors in the rms casing, but this is not a certified motor/casing combination so you could not fly them at a NAR launch or AMA flying field, and still be covered by their insurance, tripoli research or your own place would be fine. These are the correct disks you need: https://www.rocketmotorparts.com/Insulator_Disc24mm_RC/p1577809_19988065.aspx

But they have flat rate shipping so you need to order a lot or something else for it to make sense.

If you put epoxy into the standard closure/case combo I'd use jb weld You do need to be sure to always use the delay grain and all o-rings and parts of course...

Frank

 

[burkefj]

New to the forum, and first post. I have been doing RCRGs for about a year. This may be common knowledge, but I thought I would post something I learned the hard way.

I have been successfully flying my Dynasoar Rocketry Aurora Clipper (classic BT-80 version) with a variety of motors, including some requiring the 24/40 casing that needs to be plugged. My plug was just a bit of flameproof wadding in where the ejection charge would go.

It worked fine, until it didn't. On the last flight, the boost and glide were awesome! After landing though, I discovered that the delay element had burned through. There was not enough pressure to blow off the nose cone, but the hot gasses partially melted the depron motor mount pieces, forcing the retirement of the model.

I have since filled the ejection charge compartment with epoxy to prevent this from happening again.

Now, what to build to replace the AC? I like the large size, but Frank has downsized the AC. I may need to do a scratch build.

Andy

Andy, you don't need to retire the model, all you need to do is pull the old motor mount out, use sandpaper and sand down the motor mount foam strips back to the cardboard, and glue new pieces onto the old or a new 24mm motor tube and re-glue it in, you can even rotate the mount so that the strips won't interfere with the old glue that was there. If the tab on the fin got a bit of damage you can sand the remnants flat and glue some spare depron onto the stub inside the tube at about the same length, then insert the mount. On low thrust motors I'd say you don't need to glue the fin to the motor tube, but if you are trying to run F-24's you certainly do. Worst case you can pull the old fin out and glue a new one in. I've even done this on my big H-13 powered models when a burned through single use H-13 damaged the centering strips, works no problem at all.

BTW, the wing is almost identical between all models, just the length and body tube size is different leading to massive weight reduction. Equipment fits just as in previous designs. In fact the BT-80 is not "classic" per se, it was the second iteration of the design, the first using PS-II cones and tubing of 2", then I switched to BT-80 and PNC-80K which cut the weight by an ounce, now switching to BT-60 has reduced it another 2 ounces so that it is now under the registration marking rule required by FAA for drones, if that matters to anyone. They all used the same E-6 as designed. Note Andy has reinforced his wings with tape to allow for faster burning motors.

 

[bronicabill]

I used a 2-56 screw in the flash hole, inserted from the inside of course, on my 29/40-120 casings (need to tap the hole first). Works great, and easily removeable if I want to use motor ejection on a model.

 

[SolarYellow]

I used a 2-56 screw in the flash hole, inserted from the inside of course, on my 29/40-120 casings (need to tap the hole first). Works great, and easily removeable if I want to use motor ejection on a model.

My understanding is that will also relegate the motor (and even the casing with the screw removed) to "research" status, making it no longer flyable at AMA or NAR fields.

 

[Crawf56]

I have used JB Weld to plug D12-0 motors.

Strongly suggest you use a Stop Ring on your motor mount.

 

[burkefj]

I have used JB Weld to plug D12-0 motors.

Strongly suggest you use a Stop Ring on your motor mount.

Only for BP motors, the rear closure ring stops the casing just fine without a thrust ring.

 

[sr205347d]

Andy, you don't need to retire the model, all you need to do is pull the old motor mount out, use sandpaper and sand down the motor mount foam strips back to the cardboard, and glue new pieces onto the old or a new 24mm motor tube and re-glue it in, you can even rotate the mount so that the strips won't interfere with the old glue that was there. If the tab on the fin got a bit of damage you can sand the remnants flat and glue some spare depron onto the stub inside the tube at about the same length, then insert the mount. On low thrust motors I'd say you don't need to glue the fin to the motor tube, but if you are trying to run F-24's you certainly do. Worst case you can pull the old fin out and glue a new one in. I've even done this on my big H-13 powered models when a burned through single use H-13 damaged the centering strips, works no problem at all.

BTW, the wing is almost identical between all models, just the length and body tube size is different leading to massive weight reduction. Equipment fits just as in previous designs. In fact the BT-80 is not "classic" per se, it was the second iteration of the design, the first using PS-II cones and tubing of 2", then I switched to BT-80 and PNC-80K which cut the weight by an ounce, now switching to BT-60 has reduced it another 2 ounces so that it is now under the registration marking rule required by FAA for drones, if that matters to anyone. They all used the same E-6 as designed. Note Andy has reinforced his wings with tape to allow for faster burning motors.

You're right Frank. With a little rocket surgery, it will be back in service!

Thanks for the tip about needing an insulator. I'll just go with the plugged ejection charge well.

 

[sr205347d]

You're right Frank. With a little rocket surgery, it will be back in service!

Thanks for the tip about needing an insulator. I'll just go with the plugged ejection charge well.

After a little surgery, flew it with an E18.

This is usually a crowd pleaser, but not this time!

 

[burkefj]

After a little surgery, flew it with an E18.

This is usually a crowd pleaser, but not this time!

Looked good you mean there was no crowd to watch it?

 

[sr205347d]

Looked good you mean there was no crowd to watch it?

There was a small audience. And he (a five month old baby) voiced his displeasure.

 

[sr205347d]

And, here it is flying with an F24.

 

[n3tjm]

I've plugged them simply by putting masking tape over the delay element. Then fill the space inside the o-ring with grease and cap the ejection well with tape.