Cherokee-D BT's.

[jeffyjeep]

Can someone tell me the lengths of the BT55's of both versions of the Estes Cherokee-D (#K-47 and 1247?) I've been trying to search Ye Olde Rocket Plans for the answer but I've been unsuccessful.

Thanks!

[rocketguy101]

Can someone tell me the lengths of the BT55's of both versions of the Estes Cherokee-D (#K-47 and 1247?) I've been trying to search Ye Olde Rocket Plans for the answer but I've been unsuccessful.

Thanks!
search the forum, instead :D
http://forums.rocketshoppe.com/showthread.php?t=6444

[jeffyjeep]

Ah so! Thank you.

[dvmanning]

The Cherokee - D Kit # 1247 shows a BT-55V tube. Further research indicates that the V designation was for a BT-55V tube that was 16.35 inches long. The 16. 35 inches converts to 16 23/64 or 16 3/8 inches The 23/64 is 1/64" short of 3/8 inches.

Here is the Estes link to the Kit # 1247 Pdf.
http://www.estesrockets.com/media/instructions/001247_CHEROKEE_D.pdf

Semroc part list for the K-47 Cherokee-D kit also shows the BT-55V tube.

http://www.semroc.com/store/scripts/ClassicParts.asp?ID=56

[jeffyjeep]

Thanks. Semroc does indeed show it as BT-55V, but not the length. Semroc appears to have descriptions only for tube lengths in stock.

[rocketguy101]

Thanks. Semroc does indeed show it as BT-55V, but not the length. Semroc appears to have descriptions only for tube lengths in stock.
This is a handy reference for the Estes body tube lengths http://www.rocketshoppe.com/info/Estes_Body_Tube_List_3.1.pdf

it is located on Ye Olde Rocket Shoppe here http://www.rocketshoppe.com/tips.htm

[jbuscaglia]

This is a handy reference for the Estes body tube lengths http://www.rocketshoppe.com/info/Estes_Body_Tube_List_3.1.pdf

it is located on Ye Olde Rocket Shoppe here http://www.rocketshoppe.com/tips.htm

You can also find it in the Estes Custom Parts Catalog (http://oldrocketplans.com/pubs/Estes/Estes_Custom_Model_Rocket_Parts_Catalog.pdf) on Ye Olde Rocket Plans.

[ghrocketman]

The original K-47 and the EARLY 1247 used the BT-55V.
The 1247 changed to the full-length 18" BT-55 right around the same time it changed from a BNC-55AC cone to the PNC-55AC cone. I have NEVER seen a kit with the plastic nose cone and short tube, nor have I seen a kit with the balsa cone and long tube other than a clone.

It is MUCH more stable with the long tube. If you want the short-tube version, use plenty of nose weight.

I personally think the long-tube version looks better.
The Cherokee-D was my first D-power rocket and I have lost more of them than any other rocket.
An 18" chute on a rocket this small and flies so high is JUST PLAIN DUMB.
A 12" is plenty and use that with a D only in very light wind. Otherwise, use a STREAMER if u want it back.
Interestingly, the only time I have lost them has been using the D12-7.
Never lost one on a D12-5 or on the long discontinued D11-9. The D11-9 is about a perfect motor for the Cherokee-D; it has a little less total impulse than the D12 and the 9 second delay is about perfect with a streamer.

I actually flew one on an Aerotech E15 with streamer recovery in zero wind and got it back. Landed within 100' of my backyard pad. I think that thing must have hit at least 3000'.

[tbzep]

The original K-47 and the EARLY 1247 used the BT-55V.
The 1247 changed to the full-length 18" BT-55 right around the same time it changed from a BNC-55AC cone to the PNC-55AC cone. I have NEVER seen a kit with the plastic nose cone and short tube, nor have I seen a kit with the balsa cone and long tube other than a clone.

It is MUCH more stable with the long tube. If you want the short-tube version, use plenty of nose weight.

I personally think the long-tube version looks better.
The Cherokee-D was my first D-power rocket and I have lost more of them than any other rocket.
An 18" chute on a rocket this small and flies so high is JUST PLAIN DUMB.
A 12" is plenty and use that with a D only in very light wind. Otherwise, use a STREAMER if u want it back.
Interestingly, the only time I have lost them has been using the D12-7.
Never lost one on a D12-5 or on the long discontinued D11-9. The D11-9 is about a perfect motor for the Cherokee-D; it has a little less total impulse than the D12 and the 9 second delay is about perfect with a streamer.

I actually flew one on an Aerotech E15 with streamer recovery in zero wind and got it back. Landed within 100' of my backyard pad. I think that thing must have hit at least 3000'.

I agree on everything except which version looks better....and the short one is stable enough in most situations, but I do add a quick link to the nose if I'm boosting on 24mm motors. BTW, did you copy and paste that post? Without doing a search, I bet it's almost word for word with others you've made about this very topic. :D :cool:

[ghrocketman]

Nope, did not copy & paste.
That'd be cheetin'.
I don't cheet.

[PaulK]

Can't let a Cherokee-D thread go without adding something. The 18" version is the *right* length to me, perhaps since that was the length of my first one "back in the day". I've built both, but my upscales are based on the long version. Agree about nose weight, a D12-7 on the short version w/ Balsa NC needs a large steel washer to be stable. My most recent clone was a BT55 18" tube, with a 29mm mount for the Estes F15. Needed to entirely fill the plastic NC with clay, but flies great! :D

[ghrocketman]

Wow.
A 29mm F15 in a Cherokee-D.
Wonder if it goes any higher than one powered by an Aerotech E15/E30 as the motor weighs a lot more and so would the rocket due to all the clay in the nose. I'm thinking all that weight would offset the extra ~10n-sec of total impulse the F15 has over the E15/E30.

I always have at least one 18" Cherokee-D in my fleet.
The last one that I LOST was on either an E9-6 or E9-8. Winds were very low at ground level but were NOT at apogee ejection height.
A 12" chute was way too much for the winds up at around 2500'...should have used a long streamer instead. I think I lost that one in like 2007 or 2008.

[Bob H]

Can't let a Cherokee-D thread go without adding something. The 18" version is the *right* length to me, perhaps since that was the length of my first one "back in the day". I've built both, but my upscales are based on the long version. Agree about nose weight, a D12-7 on the short version w/ Balsa NC needs a large steel washer to be stable. My most recent clone was a BT55 18" tube, with a 29mm mount for the Estes F15. Needed to entirely fill the plastic NC with clay, but flies great! :DFunny, because my first one was the short version, that is the one that is *right* for me.

When I built the upscale using Semroc 225 tubing (OD is 2.43) the calculated length for the short version came out to 29.985" and Semroc had a 30" tube.

I did not remove .015" from the tube. :rolleyes:

[jeffyjeep]

Wow.
A 29mm F15 in a Cherokee-D.
Wonder if it goes any higher than one powered by an Aerotech E15/E30 as the motor weighs a lot more and so would the rocket due to all the clay in the nose. I'm thinking all that weight would offset the extra ~10n-sec of total impulse the F15 has over the E15/E30.

I always have at least one 18" Cherokee-D in my fleet.
The last one that I LOST was on either an E9-6 or E9-8. Winds were very low at ground level but were NOT at apogee ejection height.
A 12" chute was way too much for the winds up at around 2500'...should have used a long streamer instead. I think I lost that one in like 2007 or 2008.

+1 to the streamer concept. I'm going to making the fins from basswood, so a 48" streamer should be plenty.

[PaulK]

Wow.
A 29mm F15 in a Cherokee-D.
Wonder if it goes any higher than one powered by an Aerotech E15/E30 as the motor weighs a lot more and so would the rocket due to all the clay in the nose. I'm thinking all that weight would offset the extra ~10n-sec of total impulse the F15 has over the E15/E30.

I always have at least one 18" Cherokee-D in my fleet.
The last one that I LOST was on either an E9-6 or E9-8. Winds were very low at ground level but were NOT at apogee ejection height.
A 12" chute was way too much for the winds up at around 2500'...should have used a long streamer instead. I think I lost that one in like 2007 or 2008.

Not much higher - A quick 'n dirty sim, ignoring the lack of ideal delay times, says:

1160' for a D12
1780' for an E9
2120' for an E30
2340' for an E15
2470' for an F15 (with the additional 2 oz nose weight)

YMMV. I have no idea how high it actually went, other than out-o-sight. The long burn, though, is great fun! I was lucky to recover it after the first flight, and don't expect to next time...