Astron Skydart II Build

[Fred Garvin]

Another rocket I've been working on in parallel to the Cerberus is an Astron Skydart II. I needed a boost glider flight for NARTREK Silver, and I mostly build Estes rockets at this point, so I chose the Skydart over the Tercel. I've read some "iffy" threads on this rocket, but one was brought to our last launch and flew very well. Let's see how I do with it....

It's a Skill Level 3 kit:



Not too many parts, but alot of balsa wood to work with in this kit:



The Skydart ejects the rocket assembly "innards" and glide recovers the main body. You start with a weighted piece for the top of the motor/stuffer tube:



The other end of the motor is typical, with a thrust ring inside, engine hook and centering ring. However, there are (2) mylar rings. One goes under the engine hook, and the other goes over it:



The main wing is 4 sections:



Once sanded and fitted, they are edge glued together. I use wax parchment paper (for baking) underneath at first, and once setup has begun start cleaning up the excess glue then leave to setup fully.



This little bugger threw me. It's a tail piece for the tiny plastic adjustment screw. Instructions say "twist in and create threads"....okay, that would work if the hole wasn't already too friggan big...so I decided to fab up another with a small hole I could tap threads....first one split....%$#@#@%....second one, dang bit wobbled and another big hole....&^^%$#$.......)((&%#$^$#........third time was a charm.....I hope....(bottom one)....I did "feel" it threading in and I did set the threads with CA. As far as it actually working....we'll see.



Wing assembly complete:



Next up, the main body tube.

 

[Fred Garvin]

The main body tube is simply glued on:



There is a smaller tube to cut that simulates "intakes" on the main BT:



Cut, sanded and trimmed, ready to attach to the body:



These were sort of a pain to get glued up. I did better on one than the other, but once sanded and painted nobody will notice...



The Skydart II is basically assembled. The finished motor assembly is at the bottom. It will have a chute rigged around the center, and gets inserted into the back of the glider. There's a tab on the Boost Rocket Assembly that holds the elevator neutral, and when ejected allows the elevator to snap to a pre-trimmed position. I'll post photos of this mechanism after paint, as that is when the elevator is attached and rigged, then tuned.



I'm thinking of deviating from the kit color scheme of all white....

 

[P-40Warhawk]

It's coming along nicely, Fred! I have this kit and look forward to building and flying it.

Do you (or anyone else) know if this is the same Skydart kit that Estes had in the early 70s? I had one of those and, although the dimensions look similar, my hazy recollection makes it seem larger than the Skydart II. All I remember about that old kit (I was about 10 at the time) is that I had such a heavy coat of paint on it that I'm amazed it flew reasonably well...probably which is why it seemed so large!

Mark

 

[Fred Garvin]

Thanks!

I don't have an answer to your question......

I'm sitting here twiddling my thumbs.....all 3 of my rockets are in the paint shop....Skydart and Saturn V are primered, the Cerberus has color but needs clear.....and we've got a front to our north, generating pop up thunderstorms....it's wicked hot and humid....looks like no painting for the next couple days.....

 

[gpoehlein]

It's coming along nicely, Fred! I have this kit and look forward to building and flying it.

Do you (or anyone else) know if this is the same Skydart kit that Estes had in the early 70s? I had one of those and, although the dimensions look similar, my hazy recollection makes it seem larger than the Skydart II. All I remember about that old kit (I was about 10 at the time) is that I had such a heavy coat of paint on it that I'm amazed it flew reasonably well...probably which is why it seemed so large!

Mark

I haven't built mine yet, but I think it is fairly close. The main difference seems to be the "engine fairings" in the underside - the original had cardstock fairings while this version has you split a body tube into halves lengthwise for the fairings. The nose cone is also plastic rather than balsa - this is a new cone and I haven't checked to see how close the profile is to the original BNC-50K.

 

[JumpJet]

Do you (or anyone else) know if this is the same Skydart kit that Estes had in the early 70s?

It's the same size model. The wings and tail profile should be almost identical to the original. I changed the folded paper intakes on the sides of the model with cut sections of body tube. The internal motor mount assembly is completely different since I could not use lead weights like the older kit had, I instead had to used Steal washers. There are many other small differences like a plastic nose cone instead of a balsa cone but the overall size of the model is correct.


John Boren

 

[P-40Warhawk]

Thanks gentlemen for answering my question!

Mark

 

[Cookie the Dog's Owner]

Nice work, as usual. I find myself reading a lot of your build threads, and I like how you document the build.

 

[Fred Garvin]

Thanks Cookie!

I'm still at a stop....summer storms in the area have the humidity too high. I'm not complaining though....NEVER complain about rain in Texas in the summer......

 

[bradycros]

Looking good so far!

 

[eedetail]

Thanks John Boren, for helping bring back the classic kits I had as a kid...
I think the Skydart was my first skill level 4 build, I still have the rocket.
It last flew when a friend tossed it with the power pod inside, to see how well
it glides. Bent the airframe a bit when it "landed" I straightened it out enough that
I think it would probably eject.... I might give it one more flight before retiring it
and building it's replacement.

Nice build going Fred, I look forward to seeing it done!

 

[Fred Garvin]

Thanks John Boren, for helping bring back the classic kits I had as a kid..

X2...thanks John....it's fun to build them again....BTW...I need a Gemini Titan (#1978)....hint....hint....

 

[ereinert]

Definitely a cool add to your fleet. What size motor does it fly on?

 

[Fred Garvin]

18mm....

I don't know if the Skydart will be ready to fly Saturday. I've lost 4 days so far due to the weather. I got the Cerberus done and ready, plus the Loadstar II can fly the payload flight. I wanted to use the Saturn V for my Scale judging and flight...but it won't be ready. I can always use the Bully 12D, V2 or most likely the Redstone/Liberty Bell 7.....Boost Glider is where I'll come up short if I can't finish the Skydart in time.

 

[Fred Garvin]

I managed to get the Skydart Finished up. I went with black....looks better in person as the camera flash really accentuates the minor imperfections:



I performed a few tests of the glider. I drop tested the motor assembly from my 2nd story balcony in the house and it performed very well. Good descent rate on the stock 15" chute. The I tuned the glider. This is accomplished by turning a little teflon screw on the vertical fin. The rear elevon is attached to the glider with strong tape. It is held in the full "up" position by elastic cord. The teflon screw adjusts the stopping point. You simply toss the glider, and if it climbs, adjust the screw one way, and if it dives, adjust it the other way, until the elevon has the proper angle for straight and level flight. In boost mode, there is a wooden catch that holds the elevon flat. Once the ejection charge fires and ejects the rocket motor assembly, the elevon is released and springs up as far as the teflon screw will allow it.



That is how it is "supposed" to work.....we'll see.....:smile:

 

[ereinert]

Awesome! So it ejects the entire motor mount? You will have to keep your eye on that one as not to lose it.

 

[mwtoelle]

Awesome! So it ejects the entire motor mount? You will have to keep your eye on that one as not to lose it.

The motor mount comes down on its own parachute.

 

[Fred Garvin]

Didn't get to fly it Saturday....I felt the winds were just a bit on the risky side...my Loadstar II had just crashed....and I was out of time and had to get home.....maybe I'll get a chance in 2 weeks at the HPR Launch....

 

[eedetail]

Looks Great in black! Did you leave the half-body tubes off? Just curious how they look. I left the paper nacelles off the one I built in the 70's, and have the reissue somewhere in my build cue.

 

[Fred Garvin]

Thanks....I put them on,but they're hard to see in black.....

 

[samb]

Great looking Skydart, Fred. It is definitely a rocket for calm(er) wind conditions. I built one a few years back from the JimZ plans and have 8 or so flights on it, including a couple of lawn darts. I used some info posted on YORF by Eagle3 in my build.

https://www.oldrocketforum.com/showthread.php?t=2294&page=1&pp=10&highlight=skydart

 

[Fred Garvin]

Thanks Sam...nice Skydart you built too....I like the squared cowls.....hopefully I'll get to fly mine next launch.....maybe at the HPR launch......

 

[shreadvector]

Adfvanced warning for all similar gliders with internal ejecting motor pods: Trim for a slight stall. REASON: After ejection, there will be a small amount of residue or debris inside the front of the gliding portion and that can add enough nose weight to make it dive and crash. The debris can be bits of the clay ejection cap and/or other crud that came from the inside of the motor.

Also, if the elasitc that pulls the elevons upward is a bit weak, then the aerodynamic force of the wind blowing across the elevon will try to force the elevon down, reducing the lifting force. If you have very strong elastic, this is not an issue.

Finally, trim for a circling glide otherwise it may glide perfectly and fly a mile or two in a straight line.........

If you or anyone brings your Skydart to the annual AMA Expo in Ontario CA you can have Larry Renger autograph it and you can get your photo taken with him and the Skydart. He is at the Expo every year as a volunteer in one of the local model airplane club's booth.

 

[Fred Garvin]

Thanks for the advice Fred. I rigged the elastic pretty tight. When the rocket assembly ejects, the elevon "pops" up to the screw.

How do you "trim for a circle"? All I could do was trim it so it was straight and level, with a slight rise in the nose. I didn't see any way to trim for turns.

 

[shreadvector]

Page 14:

https://www2.estesrockets.com/pdf/2266_TR-4_Boost_Gliders.pdf

Thanks for the advice Fred. I rigged the elastic pretty tight. When the rocket assembly ejects, the elevon "pops" up to the screw.

How do you "trim for a circle"? All I could do was trim it so it was straight and level, with a slight rise in the nose. I didn't see any way to trim for turns.

 

[Fred Garvin]

What's the best way, with these Skydarts, to add a little weight to the outside wing tip? Is it so slight to be a blob of epoxy?

Thx...BTW.

 

[shreadvector]

Trim weight is usually "clay" which means the non-drying plasticene modeling clay sold in craft stores and provided in extes kits as nose weight or trim clay for gliders.

What's the best way, with these Skydarts, to add a little weight to the outside wing tip? Is it so slight to be a blob of epoxy?

Thx...BTW.

 

[JumpJet]

I personally would not add ANY weight to the tip of this model before it has been flown. It is virtually impossible that the left side of the model weighs the same as the right side. Between the density of the wood from sheet to sheet and the amount of primer and paint added it would be almost impossible for the model to balance dead center. The other BIG issue is that it will be very difficult to throw this model high enough to see if it turns one way or the other once it settles into a glide, believe me I tried during it's development. I would fly the model on a B motor and see how it glides. If it tends to glide in a straight line then I would add some clay to a wing tip before flying it on a C motor.

John Boren
Estes R&D

 

[Fred Garvin]

Thanks John....that's what I'll do.

 

[dander]

Bumping an old thread......

I am considering one of these, I've never built a glider. So Fred, how'd it work out? Inquiring minds want to know.

Thanks, Dave