Storminator

[aerostadt]

Apogee describes the Egg Storminator as a "model rocketry designed around the rules of NAR's competition event called "Fragile Precision Payload". The object of this event is to carry a raw egg and altimeter to a target altitude of 300 meters and a duration of 40 seconds." Having been a TARC mentor for several years I decided that I should try out this model. Obviously, this model cannot be used for the TARC contest and in any case the TARC contest rules change every year. However, there are some basic concepts that are similar.

The Stormimator has thru-the-wall fins and is built with strong fins. It does use rail buttons. I noticed that TARC 2018 stipulates that 1/4" rods can be used in the launches prior to the finals, but for the finals rail buttons are required. I found the ready-made holes for the rail button T-nuts in the body tube were a bit large and it was hard to keep the T-nuts in place during the installing process. The fins on this model are canted 2 degrees for the purpose of spinning the rocket and making the flight straighter. There is no motor retention provided in the kit. Actually, I skipped to some of the last steps in the instructions and found that the motor aft-end is secured externally with tape.

 

[aerostadt]

The Storminator comes with a soft foam nose cone. A small diameter cardboard tube is glued into the center of the foam nose cone with Gorilla glue. A Pnut accelerator can then be placed inside the tube, which is closed off with an end cap that is held in place with tape.

 

[aerostadt]

The length of the completed Storminator is about 29" and the weight with no altimeter and no eggs and no motor is 9.18 oz. I glued on launch lugs even though there are already rail buttons on the rocket, so that TARC contestants can see the difference. Also, I have not glued on the rear bulkhead plate so that TARC students can see the through-the-wall construction.






I noticed that the Storminator instructions direct the flyer to use tape for several attachments, so I asked the TARC people about this and got a quick reply from Trip Barber. The Storminator says to wrap tape around the rear lip of the motor and rear motor mount tube. TARC says that this is alright. Wrapping tape around the motor for a friction fit is "not" OK. The rules say that a mechanical retention must be used.

The rules this year require two eggs, but do not specify orientation. The orientation is up to the TARC team. I would think that lengthwise in the payload section would be best especially considering the diameter specifications in the rules.

The length of the rocket is determined by standing the rocket on a table and measuring the height. Naturally, fins slightly beyond the rear of the body tube can increase the height.

The Storminator directs the builder to tape the payload sections in place with tape. TARC says that this is alright, but make sure that everything is securely attached together so that it will not come apart during flight and parachute ejection.

Commercial kits for lofting eggs are not allowed in TARC with the only modification being the addition of an altitude compartment. The Storminator would not work for TARC 2018, because the specified body tube diameters are different. However, I am thinking that the Storminator can be a good illustration to show a TARC class and help a mentor to become more familiar with the issues involved.

 

[dhbarr]

Consider adding linear lugs to complete the demonstration of common rod/rail adapters?

 

[aerostadt]

Consider adding linear lugs to complete the demonstration of common rod/rail adapters?

I'm not familiar with linear lugs. Can you tell me more?

 

[dhbarr]

Just meant something like https://m.publicmissiles.com/launch_lugs.aspx to illustrate the three most common guide techniques.

 

[aerostadt]

Just meant something like https://m.publicmissiles.com/launch_lugs.aspx to illustrate the three most common guide techniques.

OK, I see what you mean. It is used similar to a rail button. Since it can be screwed on, it is kinda like standard rail buttons in that they are probably easiest to put on during the early part of construction. One thing about launch lugs is that they can be attached late in the construction. I found with rail buttons is that I need to reach inside the body tube to help screw the buttons in especially if the body tube button hole is too big. Linear lugs are interesting because perhaps it might be possible to just surface mount them with glue especially for LPR models.

 

[aerostadt]

One advantage of launch lugs on an LPR is that one can put a wooden dowel through the lugs, tie a string around the dowel, and slide the string to find the c.g. experimentally, neglecting the mass distribution of the dowel.