Interceptor E boost glide build"TIMBERWOLF"

[hornet driver]

As a newcomer to the forum I hope you will all bare with me as I post my first build thread. A boost glide Interceptor E. - Sounds dicey, maybe a little but I think I've worked it out. Big problems were CP-CG challenges. Some mechanics.Wind loading and trying to keep the old bird as true to form as possible so I did'nt upset the purists out there. Lets just say she's the evolution.The insperation for the build was my previous Interceptor E " ARCTIC WOLF"that was slightly modified .The pictures will begin to flow 5/28 in the evening so stay tuned. About 40% done at this time.:smile:

 

[RocketManDan]

gotta love it! Looking forward to the pictures and the thread! Awesome!

 

[hcmbanjo]

I'm looking forward to seeing it, on the bench and in the air!

 

[El Cheapo]

Dream the impossible. I like it. Best of luck. Win, lose or draw, I'm interested.

That's what I like about this hobby. Even if you fail doing something different, its still cool and people admire the effort. But, if you succeed it's really cool!!!

 

[georgegassaway]

As a newcomer to the forum I hope you will all bare with me as I post my first build thread. A boost glide Interceptor E. - Sounds dicey, maybe a little but I think I've worked it out. Big problems were CP-CG challenges. Some mechanics.Wind loading and trying to keep the old bird as true to form as possible so I did'nt upset the purists out there. Lets just say she's the evolution.The insperation for the build was my previous Interceptor E " ARCTIC WOLF"that was slightly modified .The pictures will begin to flow 5/28 in the evening so stay tuned. About 40% done at this time.:smile:

A great project to tackle.

Long ago I considered making a gliding version myself (from the original BT-55 model).

Wish you'd mentioned this before you got going (you say you're 40% done). The wings are pretty small, I was going to make them larger.

I never did figure out a good way to get good pitch stability. Had I built it, I probably would have added a left and right horizontal stabilizer to the back end. And would have had hinged elevators attached to those horizontal stabilizers, rigged to be flat on boost and pop up at ejection.

The wing would been moved somewhat more forward. And the model would have used a an ejecting internal pod (with noseweight in the front of the ejecting pod), as with the old Sky Dart and some other Estes rear-ejection glide models (Scissor-wing, Bomarc, etc.)


One thing I can suggest, if you’ve not done it yet. Do not attach the wings with negative dihedral (droop down) like the original. Negative dihedral will make it almost impossible to make it glide without ending up in a tight spiral dive into the ground. Thanks to the long “strakes” ahead of the wing if you build it with the wings flat, then the strakes might help to provide the kind of dihedral effect that swept-back wings produce (which is why the old Estes sky Dart had some roll stability despite a flat wing).

Something else I would suggest is to build a very crude small copy to test out the glide problems (testing by hand throws, not rocket boost). Say 1/2 size using a BT-50. The sort of thing that should take no more than one hour to throw together (using instant glue, and do not worry about the nose cone shape). So you can crash and bash and smash the heck out of it during glide tests, till you work out what it takes to get it to glide. Rather than let the “real” model end up being the Guinea Pig.

The Interceptor is my favorite kit of all time. Period. Attached is an image from the 1971 catalog cover, inside the catalog, and the back cover ad that ran in Model Rocketry Magazine.

- George Gassaway

 

[hornet driver]

A great project to tackle.

Long ago I considered making a gliding version myself (from the original BT-55 model).

Wish you'd mentioned this before you got going (you say you're 40% done). The wings are pretty small, I was going to make them larger.

I never did figure out a good way to get good pitch stability. Had I built it, I probably would have added a left and right horizontal stabilizer to the back end. And would have had hinged elevators attached to those horizontal stabilizers, rigged to be flat on boost and pop up at ejection.

The wing would been moved somewhat more forward. And the model would have used a an ejecting internal pod (with noseweight in the front of the ejecting pod), as with the old Sky Dart and some other Estes rear-ejection glide models (Scissor-wing, Bomarc, etc.)


One thing I can suggest, if you’ve not done it yet. Do not attach the wings with negative dihedral (droop down) like the original. Negative dihedral will make it almost impossible to make it glide without ending up in a tight spiral dive into the ground. Thanks to the long “strakes” ahead of the wing if you build it with the wings flat, then the strakes might help to provide the kind of dihedral effect that swept-back wings produce (which is why the old Estes sky Dart had some roll stability despite a flat wing).

Something else I would suggest is to build a very crude small copy to test out the glide problems (testing by hand throws, not rocket boost). Say 1/2 size using a BT-50. The sort of thing that should take no more than one hour to throw together (using instant glue, and do not worry about the nose cone shape). So you can crash and bash and smash the heck out of it during glide tests, till you work out what it takes to get it to glide. Rather than let the “real” model end up being the Guinea Pig.

The Interceptor is my favorite kit of all time. Period. Attached is an image from the 1971 catalog cover, inside the catalog, and the back cover ad that ran in Model Rocketry Magazine.

- George Gassaway

George you are sooo close . It's 7 cst let me grab a bite and the pic will flow

 

[hornet driver]

Trying to figure out why pics won't post hmmm

 

[hornet driver]

Sorry gag -I keep getting a script error message window. Never had this happen before . will talk to a buddy at work today and try agaian later I'm not all that computer savy.

 

[hornet driver]

THIS IS THE TEST GLIDE BIRD -SURFACES ARE 1/4 INCH FOAM BOARD--TAPED ON-- FLEW WELL WITH NO REAR BALLAST AND FULL DEFLECTION ON CANARDS AND REAR HORIZONTAL STABS . FINALLY YOU SEE THE TIMBERWOLF NEXT TO THE ARCTIC WOLF FOR COMPARISON WITH THE SMALLER FINAL WING LAYOUT. SORRY ABOUT REVERSING THE VERTS BUT A LITTLE CHANGE IS GOOD. IT'S THAT WHOLE CP-CG THING. FINALLY I SETTLED ON A MOVING CANARD WITH FIXED REAR STABS AND SOME REAR BALLAST FOR STABILITY

 

[hornet driver]

I TRIED TO KEEP THE "E" CLOSE TO THE ORIGINAL BUT HAD TO MAKE SOME CHANGES-THE WINGS WERE A LITTLE LARGER-ADDED REAR STABS FOR -CP CONCERNS ALONG WITH REVERSING THE VERTICAL STABS AND ENLARGING THEM . THE WINGS WERE MOVED FORWARD A BIT. I THOUGHT ABOUT TAKING ABOUT 4 INCHES OUT OF THE FORWARD TUBING BUT I FEARED FOR MY LIFE FROM THE PURISTS OUT THERE!! SHOWN IS THE TIMBERWOLF WITH FINAL WING FITTING. SOME OF YOU MAY QUESTION THE GRAIN RUN IN THE WOOD---THERE'S A REASON FOR THAT! THE WINGS ARE 2 SHEETS OF 1/8 BALSA LAMINATED WITH A SLIGHT CROSS GRAIN. I NEEDED A LITTLE FLEX IN THE WINGS SO I COULD ARC THEM A BIT. I KEPT THE SIGNITURE ANAHEDRAL KNOWING THERE MIGHT BE SOME STABILITY PROBLEMS WITH IT --LATER ON THAT. THE VERTS ARE 1/8 BALSA BUT HAVE 1/8 BASS RUDDERS AS STIFFENERS. ALL OTHER SURFACES ARE 1/4 INCH BALSA. THE VERTS HAVE BEEN SPLAYED WIDER THAN THE ORIGINAL

 

[Sooner Boomer]

That's sweet! Any chance you could post fin diagrams?

 

[hornet driver]

That's sweet! Any chance you could post fin diagrams?

Sure I'll do that Tuesday since I'm off all day that day I'll also post the C.A.M. --canard activation module diagrams.

 

[hornet driver]

THESE ARE PICTURES OF THE VARIOUS FLYING SURFACES--USUALLY PICTURED AS A BLANK WITH THE SHAPED PRODUCT NEXT TO IT. AS STATED THE MAIN WING IS 2 SHEETS OF 1/8 BALSA LAMINATED WITH ONLY A SMALL AMOUNT OF CROSS GRAIN. THE GRAIN RUNS LENGHT WISE ON THE WING. THIS LET ME ARC THE WING UP A LITTLE FROM ROOT TO TIP. SITTING ON IT'S BELLY THE WINGTIPS TOUCH THE SURFACE EVENLY WITH THE BELLY. IT TOOK OUT A LITTLE OF THE SIGNITURE ANAHEDRAL.AFTER LAMINATING THEY ARE QUITE STRONG WITH LITTLE FLEX. ALL SURFACES WERE SHAPE SANDED WITH 100 GRIT DRY-- SECOND SANDED TO FINAL SHAPE AND TUNED WITH 220. ALL SURFACES WERE THEN SPRAYED WITH SANDING SEALER AND SANDED BETWEEN COAT WITH A 3M FINE SANDING PAD. ON A SIDE NOTE NONE OF THE HOBBY SHOPS NEAR ME HAD SANDING SEALER OR EVEN NEW WHAT IT WAS:surprised: I FINALLY GOT IT AT LOWE'S. COMES IN A RATTLE CAN - IS LAQUER BASED AND DRYS REALLY FAST. MADE BY DEFT. THIS IS GOOD STUFF. TOOK THE WHOLE CAN TO DO ALL SURFACES WITH MANY COATS.

 

[hornet driver]

HAVE A COUPLE DAYS OFF SO A LOT SHOULD GET DONE . REAR EJECT BOOMTUBE SHOULD BE BUILT WITH PICTURES AND DETAILS. CONTROL SURFACE DRAWINGS WILL GO OUT FOR VIEWING. CAM DRAWINGS WILL ALSO GO OUT. THE BIRD WAS PRIMED LAST NIGHT AND FIRST SANDING DONE THIS MORNING. HAVING SAID THAT THERE MAY BE A WING SHAPE CHANGE COMING. I AM CONSIDERING ADDING A LITTLE TRAILING EDGE AREA. NO BIG DEAL BUT HAS SOME ADVANTAGES. REALLY STARTED TO THINK ABOUT THIS AFTER LOOKING AT THE COMPARISON SHOTS OF THE 2 E'S SIDE BY SIDE. THE WING MAY TAKE ON A MORE TRAPAZOIDAL LOOK. COULD USE AN OPINION FROM YA'LL ON THAT! ALSO 2 MORE POINTS I COULD USE HELP WITH. FIRST IS THE PAINT SCHEME. HAV'NT DECIDED ON ONE YET JUST NOT WHITE OR BLACK. SINCE SO MANY OF YOU USE RATTLE CANS, I'LL PUT DOWN THE AIRBRUSH FOR THIS ONE AND TAKE UP THE CHALLENGE. GIVE ME SOME IDEA'S. ALSO WILL PROBABLY HAVE A SEPERATE -SRB- MOUNTED ON THE BOTTOM FOR LAUNCH. I'VE WORKED OUT SOME IDEAS BUT AM OPEN TO ANYTHING. THE BIG THING IS SAFTEY. INCASE OF MISFIRE OR LATE IGNITION OF BOOSTER. I FIGURE A LOT CAN GO WRONG WITH THIS WHOLE THING SO WHY NOT GO FOR BROKE.

 

[KenRico]

Good Progress on a Great Project !

Am very interested in your results - keep posting !

 

[hornet driver]

That's sweet! Any chance you could post fin diagrams?

THESE ARE PRETTY SIMPLE BUT IF YOU NEED MORE DETAIL I'LL GET IT FOR YOU THE AIRFOIL WAS SANDED TO SHAPE WITH A LITTLE RELAX IN THE BACK AND A BIT OF A CURVE VISIBLE IN IN BOTH LEADING AND TRAILING EDGES . THE ROOT IS THICKER THAN THE TIP. PROBABLY TOOK ABOUT 2 HOURS TO SAND BOTH TO FINAL SHAPE. AGAIN I MAY BE MAKING A CHANGE TO THE REAR

 

[hornet driver]

OK, SO HERE'S THE DETAILS ON THE C.A.M.--THIS WHOLE THING COULD HAVE BEEN DONE MUCH EASIER WITH A RUBBER BAND BUT WHAT FUN WOULD THAT BE!!--THE HEART OF THE C.A.M. IS THE FRICTION SCREEN HOLDER. IF YOU GO OUTSIDE AND LOOK AT THE TOP CORNERS OF A WINDOW--THE LITTLE PIECE THAT THE SCREEN SLIDES UP INTO---THATS A FRICTION SCREEN HOLDER. THEY COST ABOUT A BUCK FOR TWO. I DRILLED A HOLE THROUGH THE SIDES OF IT MAKING SURE THEY WERE LINED-UP. I CUT THE BT COUPLER WITH ONLY ABOUT 1/2 INCH REMAINING PROTRUDING FROM THE REAR BT. THAT LEFT ME A PIECE OF COUPLER ABOUT 2-1/2 INCHES LONG. NEXT I GLUDED 2 PIECES OF 1/8 BASS ON THE INSIDE OF THE COUPLER FOR BRACING. NEXT I DRILLED A WHOLE THROUGH THE ASSEMBLY---SIDEWALL--BASS--BASS--SIDEWALL. IT WAS DRILLED RIGHT ON THE CENTERLINE. A 3/16ALIMINUM TUBE WAS PASSED THROUGH THE ASSEMBLY WITH THE LEVER----screen friction holder--IN THE MIDDLE. GOOD FIT! TAKE IT ALL APART!----IN THE TOP OF THE LEVER IS A SMALL PREDRILLED HOLE--LENGTHEN THAT HOLE TO ABOUT 3X ITS WIDTH -- AN X-ACTO KNIFE DOES FINE ,THIS IS REALLY LIGHT ALUMINUM. YOU SHOULD HAVE A LITTLE HOTDOG LOOKING HOLE--IT TOOK ME 2 TRYS TO GET IT RIGHT. REASSEMBLE THE C.A.M. ADDING 4 NYLON WASHERS BETWEEN THE LEVER AND THE BASS. THERE SHOULD BE A TINY AMOUNT OF TUBING STICKING OUT EITHER SIDE--CENTER THE LEVER AND EPOXY IT TO THE TUBE--LET DRY---LET DRY. NEXT CUT A LENTH OF --I THINK --1/4 TUBING -- ABOUT 1/2 INCH LONGER THEN THE COUPLER WIDTH. I SUGGEST YOU CUT ALL TUBING WITH A VERY SHARP X-ACTO KNIFE WITH MINIMAL PREASURE THIS PREVENTS DEFORMING THE TUBE -JUST ROLL IT UNDER THE BLADE ON A HARD SUFACE. NEXT CUT A 1/8 PIECE OF 3/16 TUBING AND GLUE IT TO ONE END OF THE 1/4 TUBE. SLIDE THE SPRING ON---MINE CAME FROM A BALL POINT PEN--DRILL A HOLE VERTICALLY FROM THE BOTTOM FRONT OF THE COUPLE THROUGH THE LEVER HOLE AND OUT THE TOP AT ABOUT A 7 OR 8 DEGREE ANGLE. PUSH THE ASSEMBLY THROUGH AND TEST THE LEVER. IT SHOULD DEPRESS FREELY AND REBOUN WITHOUT BINDING. YOU MAY HAVE TO PLAY WITH THE ANGLE ON THE SHOCK ROD. WHEN RIGHT--EPOXY ON THE INSIDE AND LET DRY. FINALLY WHEN DRYSAND OFF ALL EXPOSED TUBING FROM THE EXTERIOR OF THE C.A.M.. MAKE SURE TO SAND IT FLUSH AND THEN SOME. THE C.A.M. IS DESIGNED TO SLIDE IN FREELY AND IS HELD IN PLACE BY THE CANARD SPARS WHICH PASS THROUGH THE BT AND INTO THE 3/16 TUBING . THEY ARE HELD IN PLACE WITH TINY HITCH PINS. IT REALLY ONLY TOOK ABOUT AN HOUR TO ASSEMBLE. HOPE THE PICS AND DRAWINGS HELP. I MAY HAVE TO GET A BETTER CAMERA FOR CLOSER PICTURES. THE PROJECT GOES ON

 

[hornet driver]

DRAWING WERE LITTLE LITE HERE ARE SOME PICS

 

[Rocket_Man]

So Estes says this comes down with a 24 inch parachute but yours is going to glide down? Does it have a big booster section that requires the 24 inch parachute or does it glide some distance then the parachute comes out? I
see you have a section that manipulates the elevator fins after the engine ejects?

I guess I dont understand why it glides but at same time has a parachute?

 

[hornet driver]

So Estes says this comes down with a 24 inch parachute but yours is going to glide down? Does it have a big booster section that requires the 24 inch parachute or does it glide some distance then the parachute comes out? I
see you have a section that manipulates the elevator fins after the engine ejects?

I guess I dont understand why it glides but at same time has a parachute?

This one will use a rear ejection pod a la Bomarc --not yet shown in pics. The chute is for it. I'll be using the one supplied with the kit but am going to cut a small hole in the top. I'm using the original instead of downsizing for two reasons 1. if the pod begins to hang up hopefully the chute will snatch it free. 2. if the pod hangs upsolidly and I don't get seperation--the chute will handle the weight of the E with minimal damage--this all assumes the pod only partially deploys.If the pod does'nt deploy at all you'll be seeing pictures of a compact E . Actually working on the pod as we speak and will post pics in a later today . Thanks for asking, I'll try to be more clear in the future.

 

[hornet driver]

Here are pics of the ejection pod and the C.A.M. attached as the would be inside the bt. Not shown with chute . Alighnment was good with only one slight tweek needed in the wire to line up. I am however going to put a cone receptor on the C.A.M. to help with alighnment. the whole gadget is a handfull with the chute attached--as expected, but it was a trade off. Note canards are not attached at this time.

 

[Sooner Boomer]

Looks nice. Thanks for the drawings and pictures!

 

[hornet driver]

Looks nice. Thanks for the drawings and pictures!

Thanks I know they are a bit primitive If you need pros I'll run some off the drafting board. Give me a little time on that . Could use a little critical review about now. Seems everyone is quiet or disintrested. May be opening a bag of worms but I also fish ---will post a pic of where I'm at now in a few minutes , then back to reality for a few days...follow

 

[hornet driver]

Current status picture---a long way to go.

 

[powderburner]

Don't worry about the Interceptor purists, you are definitely off into new territory with this one. Whatever works is the right thing to do!

I hope it flies/glides well for you, but you are definitely going to have to be careful to build light to try to hold down the glide speeds.

I know you had your reasons for selecting the direction of the balsa grain in the wings:

SOME OF YOU MAY QUESTION THE GRAIN RUN IN THE WOOD---THERE'S A REASON FOR THAT! THE WINGS ARE 2 SHEETS OF 1/8 BALSA LAMINATED WITH A SLIGHT CROSS GRAIN.

I am afraid that (with your selected grain orientation) your wing may not be strong enough to hold together if the rocket runs into gusts or disturbances during boost, or if it has a rough landing (and if it lands hot, it's going to be rough!) Grain really does need to run spanwise, somewhere between being parallel to the leading edge or to the 50% chord line. If you need to tailor the anhedral or dihedral it is better to make a chordwise cut, separate the wing into inboard-outboard panels, and reassemble the cut with the desired angle.

Have you done any hand-launched test glides? I will be interested to hear whether your design seeks a stable attitude that is right-side-up or upside down. If it wants to do the latter, you might try kicking up a couple inches of each wingtip (like the F-4 Phantom has). Good luck, keep us posted!

 

[hornet driver]

Don't worry about the Interceptor purists, you are definitely off into new territory with this one. Whatever works is the right thing to do!

I hope it flies/glides well for you, but you are definitely going to have to be careful to build light to try to hold down the glide speeds.

I know you had your reasons for selecting the direction of the balsa grain in the wings:



I am afraid that (with your selected grain orientation) your wing may not be strong enough to hold together if the rocket runs into gusts or disturbances during boost, or if it has a rough landing (and if it lands hot, it's going to be rough!) Grain really does need to run spanwise, somewhere between being parallel to the leading edge or to the 50% chord line. If you need to tailor the anhedral or dihedral it is better to make a chordwise cut, separate the wing into inboard-outboard panels, and reassemble the cut with the desired angle.

Have you done any hand-launched test glides? I will be interested to hear whether your design seeks a stable attitude that is right-side-up or upside down. If it wants to do the latter, you might try kicking up a couple inches of each wingtip (like the F-4 Phantom has). Good luck, keep us posted!

Hand launch tests with with the prototype were better than expected . no real stability problems . Glide speed is high but that was expected with the small wing. I've shaved all the weight I could but had to add some here or there as the design required. In the end not much different than the original. Glide tests with the current version you see will start this week. There may be a minor wing change if required. As far as the grain direction goes--- it was a trade off for what I was trying to get. Frankly I'm counting on a little flex----I could be WAY off but it's worked for me before. Having said that your point is well taken. Normally I'll run the grain parallel to the leading edge just to keep it simple.

 

[Rocket_Man]

After looking at all the work you are putting into this, are you really going to launch it? If it was me I dont think I could push the button!

 

[degreaser]

Very nice design. Have you considered adding control surfaces and RC servos?

 

[El Cheapo]

Looks great. It's a lot closer to the original profile than I expected. Nice job so far.

 

[hornet driver]

After looking at all the work you are putting into this, are you really going to launch it? If it was me I dont think I could push the button!

I figure the worst that can happen is I auger in to smoking hole and then I have to buy another one and have fun doing it all over again--less the mistakes