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Interceptor E Build—- Pursley Skin

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BABAR

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Okay, I figured I’d take a break from scratch building and build the Interceptor E I bought a while back,
I also got the John Pursley Union Skin (not because I have any particular affectation for the Civil War but because I liked the dark blue color.)

Instructions have lots of warning about exceeding 425 grams.
I am going with mini rail buttons and I have a 6 foot 10x10 rail.

I fly in a medium size field (parking lot essentially with soccer fields on all side). This rocket likely will be flown once, maybe twice, I would like to get it back relatively undamaged.

I’d prefer to stick with the 24 mm motor mount,

Only recommended engine is E9-4.

Seems like Estes website doesn’t even LIST this motor



All they have in 24mm is E9-8, or the E12-4,6,8

I am thinking the E12 would be good, was thinking 4 second delay?

So do I need to worry about the weight of the skins much? @neil_w , I think you built a Ragnirak with these, so your input as usual would be appreciated.

Are the Wing Support and Fin Support pieces really needed?

Will it screw up the skins if DON’T put in supports?

For the mini rail buttons, will just screwing them into the body tube be enough? I have the crazy idea of building and finishing the rocket, putting masking tape over the button sites, drilling a small hole in each through the tape, injecting some Gorilla Polyurethane Glue in the holes, covering the holes and allowing to dry hole side down for a couple days (figure that curing might take a bit as no air circulation.). Thought that might give me some thickness or substance to hold the mini button screws in place. ????

Tho
 
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BABAR

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I read that rocket should be painted with a gloss finish for best Skin adhesion (Pursley’s, not mine). How much “finishing” do I need given the skin covering should hide some minor blemishes?
 

BABAR

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BABAR

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Should I put the tail cone on AFTER I finish Skinning?
 

neil_w

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Disclaimer: I haven't built an Interceptor E, although the Ragnarok I built is pretty much the same size, and therefore probably a very similar build overall (although I had to cut my own fins 😛)
Only recommended engine is E9-4.

Seems like Estes website doesn’t even LIST this motor



All they have in 24mm is E9-8, or the E12-4,6,8

I am thinking the E12 would be good, was thinking 4 second delay?
The E9 was the CATO-master, now discontinued. E12 might be fine, but why not just get an Aerotech E15 and then you can stop worrying about every gram. Just make sure you have a sufficient launch controller for the Aerotech igniters. My Ragnarok flew nicely on an E15, good speed off the rod (although it did arc over a bit probably due to the large wings). I look forward to flying it again. Actually, I look forward to flying *anything* again. :rolleyes:

If you could fly an E12, you can fly an E15.

So do I need to worry about the weight of the skins much? @neil_w , I think you built a Ragnirak with these, so your input as usual would be appreciated.

Are the Wing Support and Fin Support pieces really needed?

Will it screw up the skins if DON’T put in supports?
I would not worry about the weight of the skins, and again I would just fly on E15s and not worry about such things.

I'm not sure what wing support and fin support pieces are. Are those part of the skins or part of the kit? When I hear "support pieces", though, my first thought would be to keep them.
I read that rocket should be painted with a gloss finish for best Skin adhesion (Pursley’s, not mine). How much “finishing” do I need given the skin covering should hide some minor blemishes?
I would fill wood parts, apply gloss paint. A fantastic finish is not necessary, but certainly the smoother the surface, the better the skins will adhere. A light sanding with high-grit paper (800 or more) just to knock down any significant bumps could be useful. I'll need to go back to read my own build thread to remember what I did with mine.

I was initially disappointed to discover that I needed to do any painting at all; I had been hoping for a no-paint rocket. Once I thought about it, though, I realized that that was never a reasonable expectation. Knowing the paint won't be visible (except, perhaps, in bits here and there) does take a bit of pressure off the painting process.

Have fun with the build, it's very "different" and a great change of pace. And you may well want to fly the finished product more than once. :)
 

prfesser

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Instructions have lots of warning about exceeding 425 grams.
I am going with mini rail buttons and I have a 6 foot 10x10 rail.

Only recommended engine is E9-4.

Seems like Estes website doesn’t even LIST this motor

All they have in 24mm is E9-8, or the E12-4,6,8

I am thinking the E12 would be good, was thinking 4 second delay?
I think the Interceptor E came out before the change from 454 g maximum to 1500 g maximum. On my instruction pamphlet it talks about notifying FAA, etc. if the weight with motor exceeds 454 g. That's probably why the 425 g weight is mentioned in the instructions. So I wouldn't worry about the weight, at least not if it's just a few tens of grams.

I agree, go with the E12-4 for a first flight.

Best -- Terry
 

neil_w

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The E9 was the CATO-master, now discontinued. E12 might be fine, but why not just get an Aerotech E15 and then you can stop worrying about every gram. Just make sure you have a sufficient launch controller for the Aerotech igniters. My Ragnarok flew nicely on an E15, good speed off the rod (although it did arc over a bit probably due to the large wings). I look forward to flying it again. Actually, I look forward to flying *anything* again. :rolleyes:
I just looked at the Estes website and was surprised to see that they still have the E9-8 for sale. I wonder if that's just extra stock.

Back to the BABAR's question: I assume you were thinking of getting the E12s locally at HL or something? *Please* don't pay hazmat to get them, that is nuts. If you must mail order, then *definitely* get the E15s instead. (And as I like to mention as often as I can, the E20 is the exact same motor as the E15, so get whichever has the best deal or whatever).
 

neil_w

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Would the Aerotech D21 work better than the Estes E12?
Should certainly get it moving off the rod... don't know (a) how short a delay you'd need, or (b) whether ejection charge is sufficient for a large airframe like that.

RE: E20 and E15 are the same motor
There was a time when they were different. Those older thrust curves are still around. Yes, it's pretty darned confusing.

Let's put it this way: either an E20 or E15 would work fine, either way. :)
 

HHaase

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If you're going to start flying 24mm motors, I'd highly recommend the Aerotech 24/40 reloadable case. A bit spendy of an initial investment but there's just so many good reloads for it.

For this rocket the E18W would be a great fit. The F12J may also work as well, depending on the overall weight.


-Hans
 

rcktnut

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The E15's were great motors, full E nice long burn, flew lots of them. You can forget about them, they have been discontinued. It has to be just me, they discontinue all what I always thought were some of the best motors they ever made.
 

neil_w

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The new ones (which are really E20s) are great too... but I never flew the old ones to compare.
 

heada

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The E15 would be a perfect match. I have 1 left and I'm kinda waiting for a special use for it.

The E18 in the 24/40 case would be another good option and it's current so you can still get them.
 

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I fly my Cosmic Interceptor, about the same size, on the 24/60 F35 and it's very nice. Make sure to file the engine hook down so the forward closure will clear.
 

les

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I would not worry about the weight of the skins, and again I would just fly on E15s and not worry about such things.

I would fill wood parts, apply gloss paint. A fantastic finish is not necessary, but certainly the smoother the surface, the better the skins will adhere. A light sanding with high-grit paper (800 or more) just to knock down any significant bumps could be useful. I'll need to go back to read my own build thread to remember what I did with mine.

I was initially disappointed to discover that I needed to do any painting at all; I had been hoping for a no-paint rocket. Once I thought about it, though, I realized that that was never a reasonable expectation. Knowing the paint won't be visible (except, perhaps, in bits here and there) does take a bit of pressure off the painting process.
I have not filled the wood parts or tube spirals. A good gloss finish is a must though. Use a color that matches the skin so if anything shows through a gap, it blends in.
And it seems every time I got a different skin John recommended a different clear. At one point he suggested ACE clear gloss.

Here are my Accur8 birds. (but I have not built my Interceptor E version yet.....
IMG_4707.jpg
 

RobertH3

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There is a Rocksim file on Rocketreviews.com. I am building one I got off the Bay (expensive) to replace the original Interceptor one shot down by my barn cat. Sim file author is Tim Van Milligan and it looks pretty good. If you don't have Rocksim, screenshot attached next post (I have to make one). I too am staying with the 24mm to 3.75" as there is just no reason to overboost this expensive and nice kit.
I didn't like the filler pieces on the fins OR the epoxy attachment for balsa so I papered them and used TiteBond II - NO recommendation here : ) since I haven't flight-tested yet...
Epoxy is heavy, so I only used it on the plastic to wood/paper joints. I also want an RCAF decal scheme if I can find one. If not, will order an upscale of the original decals.
 

RobertH3

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Here are the Rocksim Flight simulations - looks like author used a Cd of 0.7 to 0.75 - probably not too far off with antennas, pods, and fins, not to mention the nose. I have seen three CATOS and one malfunction of the E12 series. I've flown some black powder E's and F's and had no issues - ordered directly from Estes on the assumption that they are stored at a proper temp. 100%. I don't think the E9 is a good motor for this kit even if you find some. Cheers / Robert

Note: the small RMS motors do, I think, give you a little better adjustment on delays. With the DMS motors, you have a little more speed at deployment.

Interceptor E Flight Sims.png
 

afadeev

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Okay, I figured I’d take a break from scratch building and build the Interceptor E I bought a while back,
I also got the John Pursley Union Skin (not because I have any particular affectation for the Civil War but because I liked the dark blue color.)
What a fantastic timing for this thread, I'm just sorry I haven't stumbled onto it earlier.
I am in the midst of building my own Interceptor E, with Pursley's "Twilight Chameleon Skin".

I've gotten distracted with preparations for last weekend's Club launch and one other build I have in the pipeline that has been giving me fits (Roachwerks Nike-Hercules). Finding this thread just helped me get back the Interceptor E back onto my build table. Here is what it looked like the other day (fins have been painted black now):
Interceptor E v1.0.jpg

A couple of observations on Estes 24mm motors based of this week's launches (flew Little Joe II and Expedition on D12, E12, and AT E28):
D12 and E12 have a similar initial thrust profile, but E12 is longer burning motor with greater total Impulse, but heavier. The net effect is that E12 powered flights tended to weather cock into the wind more.
I will be first flying my Interceptor E on AT E28 with ~6-7 second delay. I just don't want to re-kit the kit on the first flight: https://www.rocketreviews.com/compare-motors-124592.html
If that works well, I might step down to AT E18, again, due to aggressive initial thrust profile: https://www.rocketreviews.com/compare-motors-774118.html

BP-burning Estes motors are just not a good match for this heavy and draggy kit, IMHO.

I fly my Cosmic Interceptor, about the same size, on the 24/60 F35 and it's very nice. Make sure to file the engine hook down so the forward closure will clear.
Just say "NO" to metal engine hooks and paper motor thrust blocks.
Install a proper positive engine retainer instead!
Painted black, Estes plastic retainer fits perfectly into the overall look of the kit, see above.

24/60 is a weird case size, but the 24/40's F39 is one of my all-time favorite motors, and will definitely take its turn inside the Interceptor E.
 

BABAR

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I have not filled the wood parts or tube spirals. A good gloss finish is a must though. Use a color that matches the skin so if anything shows through a gap, it blends in.
And it seems every time I got a different skin John recommended a different clear. At one point he suggested ACE clear gloss.

Here are my Accur8 birds. (but I have not built my Interceptor E version yet.....
View attachment 431693
Thanks, those are nice looking birds.
 

BABAR

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Here are the Rocksim Flight simulations - looks like author used a Cd of 0.7 to 0.75 - probably not too far off with antennas, pods, and fins, not to mention the nose. I have seen three CATOS and one malfunction of the E12 series. I've flown some black powder E's and F's and had no issues - ordered directly from Estes on the assumption that they are stored at a proper temp. 100%. I don't think the E9 is a good motor for this kit even if you find some. Cheers / Robert

Note: the small RMS motors do, I think, give you a little better adjustment on delays. With the DMS motors, you have a little more speed at deployment.

View attachment 431831
Thanks.
Wonder how much the skins will add to the weight?
For my field, the E12-4 looks like the perfect motor if I can keep the weight close to this.

400 feet is plenty high enough for me
I guess I will build it and finish it and run the sim with the actually finished weight and CG.
 

BABAR

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What a fantastic timing for this thread, I'm just sorry I haven't stumbled onto it earlier.
I am in the midst of building my own Interceptor E, with Pursley's "Twilight Chameleon Skin".

I've gotten distracted with preparations for last weekend's Club launch and one other build I have in the pipeline that has been giving me fits (Roachwerks Nike-Hercules). Finding this thread just helped me get back the Interceptor E back onto my build table. Here is what it looked like the other day (fins have been painted black now):
View attachment 431856

A couple of observations on Estes 24mm motors based of this week's launches (flew Little Joe II and Expedition on D12, E12, and AT E28):
D12 and E12 have a similar initial thrust profile, but E12 is longer burning motor with greater total Impulse, but heavier. The net effect is that E12 powered flights tended to weather cock into the wind more.
I will be first flying my Interceptor E on AT E28 with ~6-7 second delay. I just don't want to re-kit the kit on the first flight: https://www.rocketreviews.com/compare-motors-124592.html
If that works well, I might step down to AT E18, again, due to aggressive initial thrust profile: https://www.rocketreviews.com/compare-motors-774118.html

BP-burning Estes motors are just not a good match for this heavy and draggy kit, IMHO.



Just say "NO" to metal engine hooks and paper motor thrust blocks.
Install a proper positive engine retainer instead!
Painted black, Estes plastic retainer fits perfectly into the overall look of the kit, see above.

24/60 is a weird case size, but the 24/40's F39 is one of my all-time favorite motors, and will definitely take its turn inside the Interceptor E.
Were those E12 flights on 6 foot rods/rails?

The E20 looks good too
 
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mbeels

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RE: E20 and E15 are the same motor

Did RocketReviews miss the memo
If you check thrustcurve.org, they have the same data for the E15 and E20. Rocketreviews has a fair number of mistakes and bad data, I'd trust thrustcurve, though.
 

RobertH3

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Maybe back in the day they were different? This came out of Rocksim 10...

I think I am going to add an additional upgrade. My Firefox has a 32" cutout plastic chute and is going to come in at around 9oz. This rocket needs a thread of its own since it doesn't have TTW and really needs it with the wingspan. Hopefully not paper hinges - they are good but a pain to hide.
Interceptor E comes with a nice nylon 24" chute and is going to come in at around 12-13oz painted. May need a larger chute to prevent pod / wing breakage on landing.
I am planning a dogfight drag race : ) the Fox is a 2.6" but lighter than the interceptor. Due to low flight speeds it'll probably win unless I pick different motors for same apogee.

Cheers / Robert
 

HHaase

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Cool, thanks. I had forgotten how complex that one was until I just started looking at it again.
 

BABAR

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16007277527426152850209561277061.jpg


Well, here is the stuff John Pursley recommended to coat the skins before cutting and attaching them.

Got it from Jerry's Artarama, about $16 including tax and shipping. Took about 4 days.

Wondering what i can spray it on to test it?
 

BABAR

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Thinking about a shock cord mod

Loop of kevlar around motor mount, taped and glued to the engine mount tube. Drill a hole through the lateral edge of the forward centering ring.
20200921_191847.jpg
 

mbeels

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Loop of kevlar around motor mount, taped and glued to the engine mount tube. Drill a hole through the lateral edge of the forward centering ring.
Is the loop around the end of the motor tube opposite of where the motor is? I did something similar once and the force of deployment just crushed the tube. If you can, put the loop down at the other end (where the motor hook is) so it is around the motor, that gives it much more strength and the loop won't crush anything.
 

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