Sky Blaster Build

[Richard K.]

My package with the Rocket engines arrived today so now I can continue with the build!!This is my first Rocket build so I have a lot to learn. I've built Control Line planes for several years but I don't fly anymore & since I love to build I thought I'd try something new. I'll post pictures soon.

 

[Crawf56]

Very good, sir!

 

[Rktman]

Looking forward to your build.

 

[Richard K.]

OK! Back to the build! The bottom two pictures are showing the fuselage taking shape. I use Windex to soak the wood & just about anything handy for the form. In this case it was 3 different shaped paint cans, trying to get some taper to it. When I saw the sloppy work on the motor mount I almost wanted to start it over but then again, I just cleaned it up a little & moved on to the wing & canard. I still have to sheet the bottom of the wing & then add the fins on each end and then finish the fuse.
The plans call for RC gear for the flaps but I am going to leave them out because I was never very good with RC and the start up cost would be hard on my retirement budget.
That's about it for now, I would like to hear from of you, any tips or corrections, this is my first Rocket build but I have made several Control Line planes for my amusement since I don't even fly them anymore.

Richard K.

 

[aerostadt]

Richard,
Thanks for sharing. I have used ammonia water I think sprayed on balsa for warping, but it looks like your Windex is working fine. Maybe the fuselage is thin balsa. I built the Estes AstroBlaster about 25 years ago with R/C. It flew well several times mostly without me at the controls, but I finally crashed it on a really windy day. That was a bad idea! Your build may be going faster than the AstroBlaster, which had a lot of steps, but a rectangular fuselage. The AstroBlaster was a little cramp for servo's, rcx, and batteries, but it was doable. The rear elevons were moved by torque rods from the servo going in opposite directions. The canard flaps actually controlled the nose up and down pitch. If you don't use R/C, I think you will need something to activate the elevons after burn-out. Do the wings have a camber?

 

[Bruiser]

I haven't built one of these but I have built a lot of R/C airplanes and am very familiar with construction techniques. It looks like that fuselage should be built with sheet stock on the sides of the formers. Then the sides are sanded to match the contour on the top and bottom of the formers. Following that the top and bottom sheeting is added... There should be a picture of a former with the sheeting installed somewhere on the plans...

Oh, I can see F3 and F4 on the plan sheet and it looks like you are doing something entirely different then the plans call for.

-Bob

 

[Richard K.]

Thanks for the reply's!
Bob you have good eye's, yes I tend to take some liberty with the plans just because it makes it easier for me. I made the former's with a little more curve in the top & bottom so I could bend the 1/16th sheeting and put the seams on the flat sides. The 1/4" stringers help keep everything in line. That's 1 thing I like about building from scratch, I can change things around or make a "Do Over" if it dozen't work out. Since I retired several years ago I have plenty of time to work in my shop. Some days my wife has to drag me out after 8 or 10 hours!
I know the plane should have the have the RC controls & I wonder if I'll lose it on the 1st flight. I would put them in but.....
I'll post more pictures as I move along.

Richard K.

 

[Crawf56]

How did you get the foam cores for the wings? Did you make your own, or order them from somewhere?

 

[Richard K.]

I don't have any experience with foam wings so I laid out the wing on the 1/16 balsa sheet cut the 1/8 ribs then glued them up. The wing is 34"x 8" x 1" and symmetrical . The ribs are shown on the plans.

 

[Crawf56]

I don't have any experience with foam wings so I laid out the wing on the 1/16 balsa sheet cut the 1/8 ribs then glued them up. The wing is 34"x 8" x 1" and symmetrical . The ribs are shown on the plans.

Very interesting. Good play.

 

[burkefj]

Are you going to vent the ejection charge or plug the motors? Also, for a free flight version of this model, boost/glide settings are not the same

The instructions here shows plugging the motors, and comments on the fact that boost and glide trim will be different, are you going to do some dual setting trim activated by ejection or timer?

https://www.rcgroups.com/forums/showatt.php?attachmentid=8233514&d=1442005090

 

[Rktman]

I don't have any experience with foam wings so I laid out the wing on the 1/16 balsa sheet cut the 1/8 ribs then glued them up. The wing is 34"x 8" x 1" and symmetrical . The ribs are shown on the plans.

So your wings are hollow? I thought the foam core interior was needed for strength and support, and for the wing spars to have something to anchor onto? (Since I've never built a foam-winged glider I wouldn't know for sure, I can only speculate about the necessity for the foam). At any rate I'm enjoying the details of the build.

 

[Richard K.]

Are you going to vent the ejection charge or plug the motors? Also, for a free flight version of this model, boost/glide settings are not the same

The instructions here shows plugging the motors, and comments on the fact that boost and glide trim will be different, are you going to do some dual setting trim activated by ejection or timer?

https://www.rcgroups.com/forums/showatt.php?attachmentid=8233514&d=1442005090

WOW!! Sounds like I should have done a lot more research on this project!! Somehow I thought I could build this without to many problems and I knew it would be trouble leaving out the RC controls. I was just going to build the rocket and blast off letting it come down on its own.This just might turn out to be Queen of the shop & never leave. I will check out RC Groups to see if I can figure out what to do.

 

[Richard K.]

Burkefj.....Thanks for the link to RC Groups, I wish I had seen it first. I skimmed thru the 7 pages & now I will study it further.

I would like to try a rocket glider without RC, do you know of any?

 

[burkefj]

The only non rc glider i ever buiot was the ARV condor twin glider, the rest have been rc, the astriboaster kit, then my own designs after that. Jh aerospace makes a bunch of free flight kits, others here can point to plans depending on size etc...

Frank

Burkefj.....Thanks for the link to RC Groups, I wish I had seen it first. I skimmed thru the 7 pages & now I will study it further.

I would like to try a rocket glider without RC, do you know of any?

 

[aerostadt]

I can think of one commercial rocket glider that I built and flew. It is described here on Rocket Reviews:

https://www.rocketreviews.com/pterosaur-4596.html

Both a boost glider and a rocket glider with no R/C usually change the boost configuration of the model using the motor ejection charge. A boost glider gets rid of the motor and the rocket glider does not. I would expect that the c.g. of the AstroBlaster and the SkyBlaster is mid way between the canard and the rear wing. So, to transition to glide mode you need to have the canard elevons turn down or the rear wing elevons turn up. The pterosaur had an ingenious piston system that moved forward upon the motor ejection charge firing, unlocking the rear elevons, which had a rubber band pulling the elevons up. In any case it is a challenge to change the flight configuration without R/C.

 

[Crawf56]

Back to the wings: When you said you cut your own ribs, I assumed you made several (at least 5) intermediate ribs to fit within the wing (along with an Upper and Lower Spar).

Is there an internal structure to your wing, or is it hollow?

 

[Crawf56]

Regarding non-RC gliders, there are several options D):

Apogee Components (RC and non-RC):
https://www.apogeerockets.com/Rocket-Kits/Glider-Rockets?zenid=1ltf25hk3qrj6ek8r0lam8cr63

J&H Aerospace (RC and non-RC):
https://jhaerospace.com/product-category/rocket-gliders/

Uncle Mike's Rocket Shack/Wolverine Rocketry:
https://www.unclemikesrocketshack.com/Wolverine_Rocketry/Wolverine_Rocketry.html

Estes Skydart II:
https://www.erockets.biz/estes-flying-model-rocket-kit-astron-skydart-ii-oop-3229-1/

 

[Richard K.]

Back to the wings: When you said you cut your own ribs, I assumed you made several (at least 5) intermediate ribs to fit within the wing (along with an Upper and Lower Spar).

 

[Crawf56]

That is good news on the wing construction.

Some non-RC rocket gliders use something called a "pod", with a rubber band-ish string (which you can buy at the sewing department of Hobby Lobby or Walmart).

Essentially, you want the elevator to be flat at lift off. At altitude, when the motor pops out, you want the elevators to move to 'glide' position.

I did a thread on the Estes Skydart II, that shows the mechanism:

https://www.rocketryforum.com/threads/estes-astron-skydart-ii-from-arkansas.138461/

Personally, I would like to see you build the Skydart II. Then look at options to modify the Skyblaster.

 

[Richard K.]

I've been working on the covering for the fuselage & this is the top half in a jig I made a long time ago when I was making Control Line Planes.
Its simply a flat board with the alu. screwed in place to match whatever taper or size I need. That's the top half waiting until I fit the wing. I have made a LOT of planes with it & a larger version .

Rktman & Crawl 56 asked about the construction of the wing but it is already covered so this is a picture of my working drawing that I made from the plans. I didn't use the wing flaps since I am not going to use RC. It has 8 ribs spaced no more than 2 1/2 " with 2 spars. the ribs are 1/8" & the sheeting is 1/16". It finished out at 1"and tapers a little to the end.

 

[Richard K.]

I've been working on the covering for the fuselage & this is the top half in a jig I made a long time ago when I was making Control Line Planes.
Its simply a flat board with the alu. screwed in place to match whatever taper or size I need. That's the top half waiting until I fit the wing. I have made a LOT of planes with it & a larger version .
View attachment 372385

Rktman & Crawl 56 asked about the construction of the wing but it is already covered so this is a picture of my working drawing that I made from the plans. I didn't use the wing flaps since I am not going to use RC. It has 8 ribs spaced no more than 2 1/2 " with 2 spars. the ribs are 1/8" & the sheeting is 1/16". It finished out at 1"and tapers a little to the end.

View attachment 372386

 

[Richard K.]

I've been working on the covering for the fuselage & this is the top half in a jig I made a long time ago when I was making Control Line Planes.
Its simply a flat board with the alu. screwed in place to match whatever taper or size I need. That's the top half waiting until I fit the wing. I have made a LOT of planes with it & a larger version .
Rktman & Crawl 56 asked about the construction of the wing but it is already covered so this is a picture of my working drawing that I made from the plans. I didn't use the wing flaps since I am not going to use RC. It has 8 ribs spaced no more than 2 1/2 " with 2 spars. the ribs are 1/8" & the sheeting is 1/16". It finished out at 1"and tapers a little to the end.

 

[aerostadt]

Since there are no rear elevons, you might still have the canards flaps. If you do have canard flaps, there might be a way to have elastic to pull them down during the glide flight phase. There might be a way to hold the flaps straight during the boost phase using some kind of constraint. Perhaps, maybe a string mechanism could be used to constrain the flaps and the string would burn through when the ejection charge went off.

 

[Rktman]

Looks like you switched from balsa to a fiberglass fuse? How does it compare in weight? I know it's a heck of a lot tougher than balsa.

 

[Richard K.]

Rktman, No change in material It is all Balsa.

Aerostadt, I don't think I'll try to make any changes, since this is my first rocket I'll just finish it and hang it in the shop. I do want to start over with a smaller Rocket kit and work up from there. Thanks for the tip!

 

[Richard K.]

I am still working on the Sky Blaster and today I ordered a kit, Cirrus Breeze from Apogee.It is a rocket glider only & much smaller.
Is their anyone out there that has experience with it?

 

[Crawf56]

https://www.apogeerockets.com/Rocke...r?cPath=1_92&zenid=htd85d7ocvfhq5jh9kau3d0lj7

I have not built the Cirrus Breeze, but it is on my "someday" list.

I am very fascinated by the Sliding Main Wing concept.

 

[Rktman]

I built one and had problems with the fit of the sliding box for the wing (too loose--it went into a death spiral on its first flight). Not sure if I assembled it that way or it was just a matter of production tolerances varying from kit to kit. I tightened up the fit by laying down consecutive layers of CA on the fuselage boom and sanding till I got rid of the slop. Haven't had a chance to refly it yet though, but I think it's a great well-engineered glider.

I bought its bigger brother the Stratus Gale but haven't had a chance to build it. I think it solves one of the other problems that all rocket gliders seem to have: the motor pod tends to get fried very quickly (see pics below). This larger version addresses the problem by using a coupler as reinforcement around the vent holes. You can also extend the life of the motor pod by coating the inside with epoxy. I'm also considering lining the inside with lightweight aluminum from a soda can.

TIP: getting the burn string tight enough to lock your wings back can be frustratingly hard to do. Both the Cirrus Breeze and Stratus Gale use a piece of kevlar hardened with CA and glued to a vent hole as an anchor point for the thread (see 1st pic below). Looping the thread over and around the kevlar string and tying a knot while keeping the thread taut can be exasperatingly difficult. Instead, push a shortened sewing needle through the pylon right below the vent hole and use that as your anchor point. Winding it 4 or 5 times around the pin will keep the thread taut and allow you to knot it much easier.

 

[Rktman]

Just wanted to clarify about coating the inside of the motor pod with epoxy: coat only the section ahead of the motor/engine block, otherwise you won't be able to fit the motor in.