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Archive for June, 2018
Posted by burkefj | Jun 25, 2018 @ 10:27 AM | 8,747 Views
I always thought the Centuri Skylab rocket from the early 70's was neat but never had one. Being left alone for the weekend my mindsim got the better of me and decided to do an RC rocket glider themed version.

I sat down and did some mass balancing Sims to convince myself weight and dimensions would work and the location if the wing and lateral stability, then looked in my parts drawer. I had some 2" tubing and 2.6". I picked up a bt20 nose cone pack and two white motor tubes for the tail thruster.

I thought styrofam coffee cups might work for the transition and nose and lo and behold the base of the cups were 2". I also found some small paper cups and they nested in the base of the foam cups to extend the nose. I doubled the foam cups for support and used a Depron disk in between them for stiffness and glued a coupler through the base for a shoulder. I doubled the cups for strength.

I'm using an 11" chord Depron wing with two carbon spars. Glide tests are done and it is looking good. I picked up some gold monokote trim for the wing/solar panels because I think it will look better than silver. It's 43" long and 27.5" span and 7.25 oz dry, rtf should be right around 12.5 oz , no nose weight was required. the RX and battery are mounted in the transition section.

I picked up some aluminum tube for rail button standoffs because the nose diameter is larger than the rear by 1/2". I put some skids on the bottom to make it level with the nose when landing.


Got the stickershock decals to finish off the skylab RC RG and got in some test flights today, was a bit more windy than I wanted and I had to keep the nose down into the headwind to keep it from balooning but overall not bad.

Skylab satellite themed RC Rocket glider (5 min 11 sec)

Posted by burkefj | Jun 22, 2018 @ 10:41 AM | 8,402 Views
One of my customers did this and it turned out pretty well. He sent some parts and here is my flight.

Dynasoar Rocketry Stratodart X Night Flight (1 min 36 sec)


The parts to do your own version and what I used are below:

Small gauge wire to make the jumpers to solder to the strips and connect + and – terminals from all the strips to each other. The strips can be connected from any set of pads since they are in parallel.

Red jst connector to fit the battery.

Lights

https://www.ebay.com/itm/LED-Strip-L…72.m2749.l2649

LED Strip Light SMD 3528 Flexible Tape 300led DC12V indoor outdoor lighting rope 5 meter length


Battery

https://hobbyking.com/en_us/turnigy-...pack-5pcs.html

Plan battery size, count your diides, current draw is 1 amp per 150 diodes(what I used), so with a 180mah battery using about 80 % of capacity to be safe would give 8 minutes, plenty long for pad wait, flight plus recovery.

I simply applied light strips to wing and fuse to make it easy to tell the difference between bottom and top and give light on the tail. I then used clear packing tape over the lights to protect them and hold them down.

On my stratodart I needed just a few grams of nose weight to rebalance. I left the 1s battery installed for receiver power and placed the small 3s battery for lights on the cg via a hatch. Battery weighs 19 grams so my starting weight was 11.6 oz without lights, with lights 12.2 oz, with 3s batt for night flight 12.9 oz. The stratodart has the most wing area and is able to carry the weight better.


For night flying, more is not necessarily better, you can blow out your night vision.


Here is my stratodart that I built using these parts.
Posted by burkefj | Jun 22, 2018 @ 10:28 AM | 8,362 Views
Here is an upscale of an old Estes kit. The original was a free flight glider and so to keep it stable on boost it swung the wing parallel to the fuse to move the CP rearward, and used a pop pod with extra fins that ejected at apogee to release the wing and put the glide CG back where it needed to be. I thought about doing one for a while, and did several simulations with wing folded and without.

With the wing folded and with a pop pod yielded about 75 more feet in altidude and about 1.5 ounce lighter glide weight, but at the cost of having to find the pod, I fly at a field that does not allow ejection of hot material from rocket gliders and the field is surrounded by tall crops.

With the wing folded but not using a pop pod, you also move the CP back, but then would need to put in some roll onto the elevons to counter assymetric drag, and add in the swing/release mechanism and you need to use a faster burning motor to be self stable, this yields about the same boost/glide weight, but with an optimized CG placement for less up trim required for glide and a bit more altitude.

With the wing fixed and steering on the way up yields a slightly reduced altitude but not as much as you think due to the slower burn motor/reduced speed/drag and a slightly shorter glide at the benefit of simplicity. That's the route I chose.

It's a 2.1" diameter, 28" wingspan, 11.4 ounce rtf model with a 10.2 ounce glide weight and about 13 ounce/sq foot wing loading with a .79sq foot wing, it doesn't glide that bad given the small wing area. Wing is 6mm depron reinforced with a .125 carbon spar, as is the horizontal stab and it uses just elevons for roll/pitch control.

2x upscale scissor wing transport RC Rocket glider flights (7 min 5 sec)