Upscale Cherokee-D

[Thor]

This one is a slight upscale. Just ordered the parts for it. A BT-70 upscale of the Cherokee-D with a slightly longer motor mount for Estes E9s. Using a 2.15" Giant Leap Rocketry nose cone. Wondering if Craig would mind running a basic ROCSIM for me on it assuming three different motor scenarios using a single Estes D12-3, or a E9-4 or E9-6. Planning on using two fiber centerrings, a 15" bt50 stuffer/motor tube, 1/8" balsa fins. Thanks.

[Thor]

Wow, did I do myself in good again. After my "build it tough" fiasco on my 2X Goblin I decide this one would be light but didnt realize the nose cone weighs 4 ounces and so does the rest of the rocket. The total weight wouldnt be that bad but the balance point is now way ahead of even the midpoint of the rocket so it would be WAY WAY overstable. Now I find a nice 2 ounce cone from Apogee rockets that would move the CG back where it closer to where it needs to be. Oh well! I did NOT want to add weight to the rear to make up for the heavy cone. This upscale stuff has a lot to it.

[tbzep]

There's nothing wrong with "overstable". They do tend to tip into the wind a little, but otherwise they fly just fine. The Astrocam is nose heavy and I've never had a bad flight with one.

BTW, here are my Cherokee upscales. The one on the right is an old AAA Aviation kit and the other two are scratch built based on the earlier short body tube version.

http://bellsouthpwp.net/t/b/tbzep/Rockets/kab1.jpg

[Green Dragon]

There's nothing wrong with "overstable". They do tend to tip into the wind a little, but otherwise they fly just fine. The Astrocam is nose heavy and I've never had a bad flight with one.

BTW, here are my Cherokee upscales. The one on the right is an old AAA Aviation kit and the other two are scratch built based on the earlier short body tube version.

http://bellsouthpwp.net/t/b/tbzep/Rockets/kab1.jpg

very nice looking fleet :-)

love the 4" Goblin ( $" right ? ), have one of those in the ''will do sometime' pile, I have one Ace cone left which is fairly good ,and I have custom vinyl 'decals' for the 4" from CARDE (was available from Magnum,not sure about now).

need ppl to post more pics, so I get ambitious :-)

~ AL

[tbzep]

very nice looking fleet :-)



Thanks! Yep, they are all Ace nosecones.

[Green Dragon]

Thanks! Yep, they are all Ace nosecones.

your welcome :-)

and good to know they;re Ace, seems the Ace cone is pretty close then ,as yours look 'proper' ( not too long opr short,etc - good geometry).

is that Black Brant II the FSI kit ? , always wanted one of those, but never got one, although I do have a 'reject' of that cone that's waaay out of round (shoulder and cone not concentric at all, had it in a kit back when I was an FSI dealer, they replaced it for the buyer, and told me to just keep it , very poor qc in the late 90's from FSI.

might have to clone that someday, since Semroc has the cone now, just need the boattail info ( or maybe Cark will kit it :-)

~ AL

[tbzep]

It's a scratchbuilt, but I used some old AAA or FSI tubing...can't rembember which. It's about 2" in diameter like the Cherokee-G, but it's just regular glassine, IIRC. I built it and the Cherokee-G kit back in the 80's and usually flew them on Rocketflite Silverstreak motors. All the other scratchbuilt stuff in the pic was built in the early 90's.

[CPMcGraw]

This one is a slight upscale. Just ordered the parts for it. A BT-70 upscale of the Cherokee-D with a slightly longer motor mount for Estes E9s. Using a 2.15" Giant Leap Rocketry nose cone. Wondering if Craig would mind running a basic ROCSIM for me on it assuming three different motor scenarios using a single Estes D12-3, or a E9-4 or E9-6. Planning on using two fiber centerrings, a 15" bt50 stuffer/motor tube, 1/8" balsa fins. Thanks.

Thor,

Here's a really QnD whip-up using 30" of BT-70. I selected the Apogee 70A NC for the sim, since the one you had in mind isn't in the list. 10.75" long, for comparison...

12" BT-50 motor tube, two centering rings...

Fins are similar in shape, but may need detailing for proportion...

530' on an E9-4. Deployment V is 9.5 fps. DO NOT USE the E9-6, as the Dv is in the low 60 fps range. Same restriction on the D12. Dv in the high 50's...

Length is 40.75 inches using these components, and this version is based on the 18" body tube version of the Cherokee-D. I didn't include anything else internally that might be found, like a tube coupler or other mass bits...

[CPMcGraw]

Wow, did I do myself in good again. After my "build it tough" fiasco on my 2X Goblin I decide this one would be light but didnt realize the nose cone weighs 4 ounces and so does the rest of the rocket. The total weight wouldnt be that bad but the balance point is now way ahead of even the midpoint of the rocket so it would be WAY WAY overstable. Now I find a nice 2 ounce cone from Apogee rockets that would move the CG back where it closer to where it needs to be. Oh well! I did NOT want to add weight to the rear to make up for the heavy cone. This upscale stuff has a lot to it.

Using the Apogee 70A, which may be the one you are thinking about here, the total weight is just under 13 oz...

Stability margin of 4.8 with motor. Very stable.

[Thor]

Craig, I am sorry I missed your post so it has been a while since you made it and I didnt reply, sorry about that. I am thinking this one will be somewhere between 3-5 calibers of stability once I get the right cone and will weigh around 8 ounces ready to fly without motor weight. Here is the rocket so far. I also built a short booster to use a D12-0 to get things going. I selected the flame type colors to go with my name for this fun rocket, the Brimstone. Notice the cloudhopper next to it for size. The completed sustainer upper stage weighs five ounces without the cone. The booster weighs 1.75 ounces and is 3 &1/2" long BT70 with a BT70 coupler. Fins on booster are 3.5" root, 4" leading edge, 2" tip, and 4" trailing edge made from same 1/8" balsa as was used in the upper stage.
BTW, could you adjust your run to use this cone and using the booster D12. The cone I am going to buy to replace the heavy one is from Apogee. I would really like your recommendations for flying with a single E9 in the upper stage alone and then again using the D12 booster with the upper stage and a E9. Thank you so much for your time Craig!
It is number 19470 and only weighs 2 ounces. The specs are shown on this page.
http://www.apogeerockets.com/nose_cones.asp

[CPMcGraw]

Craig, I am sorry I missed your post so it has been a while since you made it and I didnt reply, sorry about that. I am thinking this one will be somewhere between 3-5 calibers of stability once I get the right cone and will weigh around 8 ounces ready to fly without motor weight. Here is the rocket so far. I also built a short booster to use a D12-0 to get things going. I selected the flame type colors to go with my name for this fun rocket, the Brimstone. Notice the cloudhopper next to it for size. The completed sustainer upper stage weighs five ounces without the cone. The booster weighs 1.75 ounces and is 3 &1/2" long BT70 with a BT70 coupler. Fins on booster are 3.5" root, 4" leading edge, 2" tip, and 4" trailing edge made from same 1/8" balsa as was used in the upper stage.
BTW, could you adjust your run to use this cone and using the booster D12. The cone I am going to buy to replace the heavy one is from Apogee. I would really like your recommendations for flying with a single E9 in the upper stage alone and then again using the D12 booster with the upper stage and a E9. Thank you so much for your time Craig!
It is number 19470 and only weighs 2 ounces. The specs are shown on this page.
http://www.apogeerockets.com/nose_cones.asp

Thor,

No problem on the response; I'll look into this variation and get something worked up for you...

[CPMcGraw]

Thor,

Here's the work-up for that Apogee NC version, with a little internal beefing-up.

I've run three simulations using the D12-0 for a booster motor. Forget using the Estes E9 for the sustainer, unless you reef that chute for a delayed opening. I found three motors that provide very good altitude performance, with less than 20 FPS deployment-Vs. One motor in each of three classes -- D, E, and F...

[Thor]

Craig, could you type out the results, I dont know how to read the zip file. You mentioned that it worked fine on an E9 as a single rocket but are you saying it wouldnt work with an E9 in the upper stage if boosted by a D12-0? I am a bit confused. Thanks!

[CPMcGraw]

Craig, could you type out the results, I dont know how to read the zip file. You mentioned that it worked fine on an E9 as a single rocket but are you saying it wouldnt work with an E9 in the upper stage if boosted by a D12-0? I am a bit confused. Thanks!

No, you can use the E9-6; I didn't mean to imply otherwise. It's the deployment-V that can cause some problems in this configuration. See the results below:


D12-0 / D12-5..........885'..........18.7 FPS
D12-0 / E30-7..........1542'.........18.5 FPS
D12-0 / E9-6...........1225'.........33.5 FPS <-- High deployment velocity; potential for shred
D12-0 / F24-7..........1752'.........19.2 FPS


Hope this helps.

For ZIP files, go grab a copy of Download Accelerator from Tucows. :D

[CPMcGraw]

Thor,

Sorry about that last line... :o

For ZIP files, you want a copy of Power Archiver. Tucows.com again...

Download Accelerator is a download manager (also a great program, BTW...)

[sandman]

Easy solution to too much nose weight.

Make it a 3 by 24mm motor cluster. :D

It worked for me.

[Thor]

Craig, thanks again. I can unzip the files just fine, but I have no way to view them or make sense of them.
Sandman, I am going to build a 4" Goblin next year much like the one shown earlier in this thread but I am going to contract you to build a proper cone. I have seen several Goblin cones you have made on the other rocket forum and they are superb! I plan to put my first 29mm mount in that one and fly it with the reloadable motors up to and including a G64W-4
I found this report on one and it got me wanting to build another larger Goblin that uses reloads.
http://www.davesnothome.net/rockets/reports/goblin_upscale.htm

[sandman]

I'd be happy to make you a 4" Goblin cone but...a 4"???

For a four incher I'd put a 38mm mount in it and reduce it down with an adaptor for 29mm.

THAT would make a SAWEEET level 1 rocket!

Heck...even level 2!

[Thor]

I finally fired off the two stager Brimstone. Bottom was a D12-0 and sustainer was an E9-4. Rocket weighed in at 8 ounces for the top stage and 10 ounces for the combined two stage minus motors. Beautiful roaring lift off on a 5' 3/16" rod, and it appeared a perfect flight to around 1300' AGL (eyeballed) Booster sustained a complete fin break on one of the three fins and sustainer suffered a major dent in the fin where the fin hit the nose cose during parachute opening. She will fly again. I LOVE the d12/E9 combination.

[A Fish Named Wallyum]

That's odd. I just stumbled onto your birthday announcement over at TRF a couple of minutes ago and I was wondering where you'd gotten to. Sounds like you had much of the same experience as I had with my Vector V upscale. Even with 8' of elastic/Kevlar shock cord, I had a nose cone rebound that crushed a fin. At the bottom. Go figure.
Happy birthday, btw.

[Thor]

Sandman, can you give me an estimate on cost for that Goblin nose cone. Tube would be a 3.9" ID/4.0" OD BT-3.90 from Loc/Precision. Thanks! Thor

[sandman]

I PM'd you on it.

[Green Dragon]

Sandman, can you give me an estimate on cost for that Goblin nose cone. Tube would be a 3.9" ID/4.0" OD BT-3.90 from Loc/Precision. Thanks! Thor

Not sure how perfect you want the Goblin cone - if you;re nitpicky, then Sandman will fix you up :-) .

I always thought the old ACE Rockets 4" cone was very close, and a few are still around 0 I know Ken at Performancehobbies.com had a few at NERRF.

~ AL

[tbzep]

I used an ACE cone on my upscale Goblin. There's a pic of it back near the beginning of this thread. The tip is a bit too pointy, but it's about the right length, IIRC. Same goes for the Red Max upscale. The nose is way too pointy for it, but the length is about right.

The ACE cone is a lot nicer for the Cherokee upscale. It's the right length, and it's shape is much closer to the BNC/PNC-55AC (especially the PNC) than it is to the PNC-60AH of the Red Max or the BNC/PNC-55AO of the Goblin.

[Green Dragon]

I used an ACE cone on my upscale Goblin. There's a pic of it back near the beginning of this thread. The tip is a bit too pointy, but it's about the right length, IIRC. Same goes for the Red Max upscale. The nose is way too pointy for it, but the length is about right.

The ACE cone is a lot nicer for the Cherokee upscale. It's the right length, and it's shape is much closer to the BNC/PNC-55AC (especially the PNC) than it is to the PNC-60AH of the Red Max or the BNC/PNC-55AO of the Goblin.

true, not quite as rounded.

I'd have to disagree with using it for a Cherokee though - then it's not pointy enough.

Thinking a PML 4" cone would be closer, although then maybe too conical / not 'fat enough' in the midsection ( wish that were true of me, lol ) .

As for the Goblin - what about a LOC 4" cone ( more rounded ), glued to a section of BT to make it longer - would that be close ?

~ AL

[tbzep]

true, not quite as rounded.

I'd have to disagree with using it for a Cherokee though - then it's not pointy enough.

Thinking a PML 4" cone would be closer, although then maybe too conical / not 'fat enough' in the midsection ( wish that were true of me, lol ) .

As for the Goblin - what about a LOC 4" cone ( more rounded ), glued to a section of BT to make it longer - would that be close ?

~ AL

I just meant that the ACE cone is much more suited for the Cherokee than the other two rockets. It's about right for length and shape. I almost glued a dowel in the tip to give it a more pointy shape, but from any reasonable distance, it just isn't noticable. If you measure the tip of the PNC-55AC, which was used later in the Cherokee-D's life replacing the BNC version, you will find that the tip is slightly rounded and about 1/8" thick. If you upscale it to a 4" rocket (about 3X), the ACE's rounded tip isn't far from accurate. I could have used a PML cone for it but I chose the ACE. I don't remember why, as it's been over a decade since I built it.

I did a 2.6" upscale of the Goblin that way using a PNC-80 cone from a Phoenix and adding some body tube to it. It looks pretty good, but the profile isn't very accurate. I haven't looked at a LOC cone in a while, so I don't know exactly how good it would look. The Goblin cone has a fairly nice arc to it, so I imagine it wouldn't look that great.

I have my own wood lathe now, so any new upscales won't be a problem. I used a friend's a few years ago for a couple of cones, but he sold his and I had to do without until I bought mine. I built a 2.6" Red Max upscale and turned the nosecone for it, but it's been sitting for about a year and I haven't gotten around to painting it.

[Thor]

Thanks Guys, sorry to cross the Cherokee thread up with the Goblin but that is what I want to build next. I had thought of doing the BNC80k and rounding the tip and adding Body tube like you did. If I build another BT80, I might do that. I will ask SANDMAN to make me one for the 4" Goblin. He and I talked via email today and I have seen the excellent ones he makes. I cant wait! Thanks for everyones help.

[Thor]

Sandman told me today, he finished the Goblin cone. YIPPEEEE

[sandman]

I just finished Thors cone and shipped it a few minutes ago.

I also finished 2 more BT-70 sized Goblin cones for Phred at Excelcior plus a BT-70 sized version of the BNC-55AC (Cherokee D).

He should have them in a day or so.

Maybe he can post pics.

Thor, don't forget to post pics!

[Thor]

Right now my camera is down with toasted batteries and this rocket will take a long time to finish based on my available funds and the fact this is my first G power level rocket. so It will be a slow build. I have seen enough of Sandman's cone pictures to know I will be totally happy with the nose cone. I am looking forward to getting into RMS motors and have several future rockets planned to use the 29/40-120 Aerotech RMS motor. I also need decals for the Goblin from Phred but I have not contacted him on this one yet. Thanks again!

[Thor]

Got the sandman cone in and all I can say is WOW! What professional work! He is really talented and an extremely fast turn around, I was shocked. The cone is beautiful and will look great on the 3X upscale of the Astron Goblin. This will be my first build with epoxy. Was wondering what brand will do. Seems like it needs to be a bit soupy to flow through tubes and stuff to be able to place it inside of tight areas. Any advice is appreciated on epoxy.

[sandman]

Thanks, Thor, glad you like it.

As for epoxy, use West System epoxy. Easy thin flowing. Great stuff.

You can purchase it at just about any marine supply store.

It's not cheap! About $100 a gallon plus the pumps, but well worth it.

Now be careful mixing it, and any other epoxy in high heat. Like this weekend's forcast!

It can "flash over" on you which is an extreamly fast flash cure.

Mix it in an old aluminum pie plate. That acts as a heat sink and keeps the epoxy cool enough so you have time to apply it.