4x OT R/C Glider Ignition

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I have thought of taking the carriage (or sled) out along with all of the electronics out and fixing the flaps in place. There would be no guidance, which might not be good, but the weight comes down to 1 lb 12 0z, which starts to become interesting for gliding. I would still need to add the tail back in, because it is attached to the sled, but I could make a lighter tail. This might not take much work and I have 2 orbiter gliders. It's food for thought.

As I look at the ideas from Frank and Tom I could also try making a new Orbiter glider using the 1/8" balsa papered material that has served me so well on the Double Shuttle. The Double Shuttle had a max speed of 194 fps versus 265 fps for the 4xOT, which might not sound like much ,but the ratio on dynamic pressure is (265/194)^2 = 1.866 . However, the nice thing about 1/8" wings is that they have 1/4 the frontal area of the current 1/2" styrofoam wings.
 
I was going to use BT-60 tubing and half nose cones to cover the servo's on the current Orbiter construction, which is similar to the Double Shuttle. However, the BT-60 was not large enough to cover the servo's. I found some larger thin tubing that works. I thought that the thin tubing was maybe too thin, so I glued another thin tube as a half shell to the inside. I could cut half nose cones and put them in front of the coverings, but in the interest of saving weight I am not going to. I plan to use the same kind of receiver and battery that frank his gliders.

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If I were going to complete it today, I would use the lightweight 3" T300 tubing from BMS for the airframe for the glider.

Frank has also urged me to use the T300 tubing. For the 4x OT the orbiter tube is 26 inches long. BMS sells there 3" T300 in a 34" length. I got the weight from BMS some time ago. For a 26" length the T300 tubing will weight about 3.85 ounces. The 3" LOC tubing for a a 26" length is 6.26 ounces. So there is almost a 2.5 ounces savings in weight for the orbiter on the tubing alone. Perhaps, with other weight savings efforts a new orbiter can be made to glide better. In any case I have ordered two of the T300-34 tubes along with some couplers to see what they look like.
 
The 3" tubing is .035 thick, is very sturdy, that's what I'm using on my new Wolverine kits. If you want to cut another 1.75 oz or so, you could switch to 2.6" bms tubing which is .02 thick, which should still be plenty for this glider, especially given the long chord delta wing which supports most of the length.

Frank
 
I have bought both the T80-34, which is like BT-80, and the T300-34 from Balsa Machine Services. The tube on the left is the T300 and the tube on the right is the T80. Both tubes are shown below along with one of the original nose cones that I had the Sandman (Roachwerks Rocketry) make for the original 3" diameter LOC tube. The original 3" diameter nose cone does not quite fit the T300 tube, but with a lit bit of sanding I think I could make it fit. Evidently, the T300 tube has slightly different dimensions than the 3" LOC tube. I ordered a new nose cone from The Sandman today to fit the T80. The T300 looks pretty sturdy, but the T80 is pretty thin. Nevertheless, I may still make a new orbiter from the T80. We will see how things go.

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I had The Sandman custom make a new balsa nose cone for the 2.6" diameter tube. He did an excellent job in duplicating the shape and hollowed out the nose cone for me. (I might hollow it a little bit more.) It is smaller than the 3" diameter nose cone, but it is lighter. The attached picture shows the unfinished 2.6" nose cone and the 3" nose cone for comparison.

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What did your 2.6" cone wind up weighing, my pnc80bb is about 1 oz with the rear part remove and just keeping the shoulder.

Frank
 
What did your 2.6" cone wind up weighing, my pnc80bb is about 1 oz with the rear part remove and just keeping the shoulder.

Frank

Frank,
The new 2.6" nosecone weighs 1.117 oz. Finishing, which I haven't done yet, will add weight. If I hollow it out a little bit more that will take off a little bit of weight. The finished 3" nosecone, which looks nice, weighs 3.644 oz.

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I'm basically following the instructions from the original Estes Orbital Transport for the dihedral wing. For the moment I'm tacking the two wing halves in place with super-glue gel with parchment paper between the wings and the 2.6" diameter tube. Obviously, the joint will need to be beefed up later with more adhesive. These are papered 1/8" balsa wings, so the servo's will be going on top of the wings. In my original 4x OT orbiter glider I borrowed George Gassaway's technique of using 1/2" foam wings. The nice feature about that design is that the foam is thick enough that the servo's can be embedded in the foam.

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After attaching the wings as shown in the previous post, I turned the model over and put more epoxy in the wing/fuselage joint on the other side.

I had some spare papered 1/8" balsa and cut out the elevons using my scroll saw. The elevons have been attached with hinge tape.

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I attached Hitec HS-55 servo's to the elevons on the top side of the Orbiter wings. The push rods are perpendicular to the elevon joints in the middle. I would like to put covering shrouds over the servo's, but the fact that the servo's are perpendicular makes the placement of covering shrouds somewhat difficult.

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I attached extension wires to the servo's wires and cut holes in the fuselage. The holes are a little ways above the wing/fuselage joint for convenience in getting the wires inside the body tube. The servo wires were then attached to the wing and the fuselage with hinge tape. I cut shrouds for the servo's from the same 2.6" diameter tubing as the fuselage. Since the tubing is so light, I made the shrouds from 2 layers of tubing, gluing the layers together with white glue. I tacked the shrouds in place with super-glue gel and then secured them in place with fillets made with 5-minute epoxy.

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I attached two 5" x 6" sections of 1/64" ply to the underside of each glider with epoxy. This will provide stronger surfaces for the attach lugs rather than glue the lugs directly to the paper reinforced balsa. One of the gliders shows the lugs in place. I will need to make a forward pylon with another lug for each glider.

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I have put the forward pin and pylon on the half-shell orbiter with a sort of through the wall fixture. On the aft end I have put in a removable fixture that is held in place with plastic rivets. Conceivably, this fixture could be modified to have an in-flight ignition system, but I am not concerned with that prospect at the moment. Currently, the weight of this glider without the battery, receiver, or paint is about 15 oz.

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The forward pylon and pin for the light-weight (standard 2.6" diameter) orbiter has been attached. It is not through-the-wall and is attached externally with epoxy and fiber glass cloth.

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A slot was cut in the orbiter (parasite glider) aft end, so that the fin unit can slide in. The fin unit has a central 24 mm tube that could someday hold a motor. The fin unit is made pretty much with light weight parts to hold the overall weight down. The fin itself is made of 1/8" papered balsa. The current total weight with the fin unit installed with the battery and receiver is about 13.5 ounces.

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I've applied paint to the top and bottom of the half-shell glider along with a few decals from Sticker-Shock. I have several different colors of self-adhesive mono-kote, which I will try out.

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The standard orbiter/glider is very light and I have some concerns about it making through the speed of balsa. So, I attached two more small pieces of 1/64" plywood to give some extra strength before the bottom black.

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So, the one hand you have your standard 4x Orbital Transport:

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and on the other hand you've got your suped-up special missions 4x Orbital Transport. Take your pick.

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Both the white glider and the red glider are coming in around 1 lb 3 oz for full-up weight with electronics. etc. (no motor). The 2 cell Lipo battery has been moved back towards the aft end in both models.
 
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I had 2 good flights of the 4x Orbital Transport at Hellfire-22, but things did not go as originally planned. On Friday I tested the the white glider and the red glider and found that the LiPo batteries in both gliders were dead. I took out the battery on the white glider, but in the process disconnected the wires to the servo's. Reconnecting the wires meant cutting through the fuselage, which is something I did not want to do out in the field (or salt flats). Fortunately, I had a brand new battery and it was easy to replace the LiPo in the red glider. The standard 13 sec delay on the CTI J270 Green made it easy to subtract off 7 seconds with the Prodat 38 to get the desired six second delay time. Since I had concerns about the 4x OT ejecting the chute too late, I scratch built a floating avionics bay using the StratoLogger with the ejection charge on the piston. Post-flight inspection showed that the avionics bay did not fire the ejection charge. Nevertheless, the motor ejection charge worked and the glider separation was good. After the glider separated I immediately threw the flap lever on the Specktrum transmitter. The glider responded well, but I also gave it some nose-up trim. The glider was carried downwind in tight circles (the Double Shuttle half-shell configuration is conducive to circles). I tried to straighten the flight out, but was not very successful. There was no damage to the booster or glider.

On Saturday I decided to skip the avionics bay and cut down on the prep time. The wind was near zero at launch time and I had better control of the glider after separation. Again, I used the transmitter flap lever along with some up trim. At one point the glider started to drift towards the flight line and I was able to use the joy stick to bring it back. I think I was trying to use the roll trim to stop the large circles, but that did not seem to work. Just before landing it looked the glider was taking a dive, but a large joy stick nose-up gave a pretty soft landing. The two booster outboard wing tip fins broke on impact (inspection of Nadine's photo's and Tom Olson's photo's showed that). It looks like the chute shroud lines may have been entangled effectively reefing the chute for harder impact than usual. Later, I found that one push rod on one glider servo arm was disconnected. I assume that this happened after the flight. Otherwise, there was no damage.

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The floating avionics bay has a through-channel for a strap that connects to the nose cone. The bay itself does not support any load, but there are two duct tape stops that allow the bay to have limited movement. There is a electrical plug/jack that can disconnect the wire going to the ejection charge on the piston. Evidently, the motor ejection charge fired first and the piston ejection charge became disconnected from the electronics bay. Since there was only one chute, the StratoLogger drogue chute option was really the main chute deploy. Since the StratoLogger was turned on, flight date is available.

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Attached are images of the StratoLogger data captured in MS Word. The recorded altitude for the 4x OT was 795' for the first HF-22 flight, just shy of 800'. It took the model about 10 seconds to reach that height. The maximum velocity was about 300 fps. This means that the 1/8" papered balsa was able to take the aerodynamic loading, which is impressive. This stuff is light and strong. The red glider does have the structural advantage that the wing is attached to the fuselage at two locations. The booster stayed aloft for almost 90 seconds. I would estimate that the glider was about the same length of time. The Bonneville Salt Flats is a hot place. The temperature data shows that the air temperature was about 100 Deg.F at about 800' up. It was a little bit cooler at ground level being only 98 Deg.F.

View attachment 4x OT HF-22 Altitude.doc

View attachment 4x OT HF-22 Altitude Velocity.doc

View attachment 4x OT HF-22 Temperature.doc
 
I have some LoRes photo's from Nadine (Photos by Nadine, which are copyrighted). These do show some close-up detail, but zooming-in will not work good. I can see some green in the CTI J270 flame. Photo's of the booster on Saturday show that the outboard wing-tip fins are intact after chute ejection. It appears that the shroud lines are entangled and consequently the chute is effectively reefed and probably fell fast. Hence, the tip fins were broken on impact. I was thinking on Saturday that the booster was undamaged, when I picked it up. I rushed to the UROC group photo with the 4x OT. While I was standing there for the group photo, I noticed that the wing tip fins were missing. After the group photo I walked back to the landing spot and sure enough there were the two fins laying on top of the salt.

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I tried the 4x Orbital Transport this year with the new white glider. The glider is extra light using a 2.6" diameter tube. It looks like the glider was destroyed at separation when the parachute is ejected from the booster. The left elevon housing was found some distance away from the glider and booster landings. The booster right pylon pin was torn off. There was no glider response to the R/C control after separation. The glider nose and forward end were damaged probably at landing. Right now I am planning to go back to the red glider half-shell design.
 

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What was your expected max speed, as on my site instructions on motor choices they are designed for 126 fps or 85mph max speeds using the e6, I'm thinking you were maybe double that on the booster?
 
What was your expected max speed, as on my site instructions on motor choices they are designed for 126 fps or 85mph max speeds using the e6, I'm thinking you were maybe double that on the booster?

Frank, at Hellfire-22 last year my Strato-Logger electronics gave a maximum speed of about 300 fps, which is way above your 126 fps limit. Keep in mind that this was my own design using the 1/8" thick balsa covered with stationery paper and white glue for wing material. I used a 2.6" diameter tube for the glider body with the wings attached as a dihedral. There was some reinforcing on the wing underside with 1/64" ply. I could not see any damage to the glider on the way up, but the model does get up high pretty fast. Some years we have Nadine Kinney taking pictures and her photos have been good for my post-flight analysis. She was not at Hellfire this year. I am thinking that she might have been at NARAM-60. I tend to think that the glider was damaged at separation, because one pylon pin is gone for sure. In any case since the red glider worked good twice last year, I am thinking of building a similar model over the winter perhaps with electronic ignition this time.
 
Oh I thought this was my kit that you adapted to fit onto your transport

Frank, at Hellfire-22 last year my Strato-Logger electronics gave a maximum speed of about 300 fps, which is way above your 126 fps limit. Keep in mind that this was my own design using the 1/8" thick balsa covered with stationery paper and white glue for wing material. I used a 2.6" diameter tube for the glider body with the wings attached as a dihedral. There was some reinforcing on the wing underside with 1/64" ply. I could not see any damage to the glider on the way up, but the model does get up high pretty fast. Some years we have Nadine Kinney taking pictures and her photos have been good for my post-flight analysis. She was not at Hellfire this year. I am thinking that she might have been at NARAM-60. I tend to think that the glider was damaged at separation, because one pylon pin is gone for sure. In any case since the red glider worked good twice last year, I am thinking of building a similar model over the winter perhaps with electronic ignition this time.
 
I am again setting things up for in-flight ignition of the 4xOT parasite glider. Depending on my schedule I should be able to fly this with the new blue glider this year. Photo's are attached. I still need to put in some screws to secure the nose cone and make provisions to firmly close the mid-bay hatch. There are two on/off switches on the side of the glider. The forward switch turns on the R/C receiver. The aft switch turns on the motor igniter. I put in a aft-end test light bulb as shown in these photo's for bench testing the igniter. Once everything is set up, the F-switch on the Spektrum transmitter must be turned on and then the throttle lever will fire the igniter.
 

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The new Blue Glider with R/C ignition flew on Saturday at Hellfire-24. All switches worked fine and a single use plugged E6 in the glider was ignited by R/C.
 

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