Super Gnome: Estes Gnome Two-Stage Conversion

[smstachwick]

Well, there is is, my Super Gnome. My booster and sustainer motors showed up today, so I put some finishing touches on it, even packed it to flight-ready condition with dog barf and everything. CG is right at the leading edge of the sustainer’s fin assembly. I’m questioning whether that will be far enough forward. I’m hoping the enormous fin area will put CP somewhere to the rear of there, and I vaguely recall my RockSim calculations coming out that way. My trial has expired and I don’t have the cash to pay for the full version, so this will be very much a seat-of-my-pants design.


I opted to retain the aft end of the motor hook in the sustainer, I just cut it a bit and straightened it to get the sustainer motor into the booster.

The booster’s hook ended up getting cut at the forward end, while the aft end is tweaked to accommodate the additional protrusion and taped to the casing for more secure retention and a better aerodynamic profile.

If I ever fly the sustainer alone, I can bend its hook back into shape fairly easily and tape it if necessary.

Launch lug alignment is good, but their integration with the tail assembly prevents me from interdigitating the fins without cutting them and fashioning DIY lugs.

 

[boatgeek]

That looks like a sacrifice to the Rocket Gods. Once you press the button, it might never be seen again!

Should be a fun flight!

 

[smstachwick]

That looks like a sacrifice to the Rocket Gods. Once you press the button, it might never be seen again!

Should be a fun flight!

That could very well be the case. I hope it isn’t though, I’ll still have a pack of 13mm motors to use up. That upper stage will be loaded with a 1/2A3-4T, hopefully that’ll keep it low enough to be trackable.

Maybe I’ll be able to throw together a spool in that diameter, I’d be pretty much guaranteed to get that back

 

[BABAR]

Good decision to go as low as possible on sustainer Motor.

have a designated spotter to keep eyes on the booster, you are naturally going to want to watch the sustainer.

hope you get two straight trails and two short walks!

 

[smstachwick]

Good decision to go as low as possible on sustainer Motor.

have a designated spotter to keep eyes on the booster, you are naturally going to want to watch the sustainer.

hope you get two straight trails and two short walks!

I’m just using these motors as instructed. The 1/2A3-4T is marked as an upper-stage motor, and there isn’t a long-delay 1/4A3T, A3T, or A10T available. I figured trying to put a standard-delay motor in the sustainer would be pushing the thing’s structural integrity at ejection, and I’ve already had a Gnome bend under power.

For whatever reason, one of my booster motors is MIA right now. Maybe I’ll get a flight in single-stage configuration if I can’t find it and create that last matched pair.

 

[BABAR]

I’m just using these motors as instructed. The 1/2A3-4T is marked as an upper-stage motor, and there isn’t a long-delay 1/4A3T, A3T, or A10T available. I figured trying to put a standard-delay motor in the sustainer would be pushing the thing’s structural integrity at ejection, and I’ve already had a Gnome bend under power.

For whatever reason, one of my booster motors is MIA right now. Maybe I’ll get a flight in single-stage configuration if I can’t find it and create that last matched pair.

I am Gnome-less, so no knowledge of structural integrity of that particular bird.. If you have room for a slightly longer Kevlar cord, I think you‘d do fine with the 1/4A3T. But you should be fine on a low wind day with few clouds (beware, Der Micromeiseter and Gary Byrum are rumored to hang out in low lying clouds. They are easily amused. Those rockets you launch and never land? It’s them.)

best wishes.

 

[DAllen]

Get the brightest colored streamer possible for visibility. Surveyors tape found at almost any hardware store is great - and cheap.

 

[smstachwick]

I am Gnome-less, so no knowledge of structural integrity of that particular bird.. If you have room for a slightly longer Kevlar cord, I think you‘d do fine with the 1/4A3T. But you should be fine on a low wind day with few clouds (beware, Der Micromeiseter and Gary Byrum are rumored to hang out in low lying clouds. They are easily amused. Those rockets you launch and never land? It’s them.)

best wishes.

Right now the plan is to fly it at Holtville Havoc. Usually not a cloud in the sky, plenty of eyes to watch it come down.

 

[BABAR]

Get the brightest colored streamer possible for visibility. Surveyors tape found at almost any hardware store is great - and cheap.

I can validate that, one roll will last you a long time. Also, while 10 to 1 length to diameter rule works for drag coefficient (meaning going over 10 to 1 doesn’t slow the Rocket down much more), VISIBILITY is pretty much directly related to length, especially if there are bushes or tall grass. So go with the longest streamer that EASILY ejects. It will help with visibility on descent AND on the ground.

 

[Bowman]

I can validate that, one roll will last you a long time. Also, while 10 to 1 length to diameter rule works for drag coefficient (meaning going over 10 to 1 doesn’t slow the Rocket down much more), VISIBILITY is pretty much directly related to length, especially if there are bushes or tall grass. So go with the longest streamer that EASILY ejects. It will help with visibility on descent AND on the ground.

That's the little rocket that my daughter flys with rapid turn around. I initially thought she had a "Quick Silver" but the name Gnome jogged my memory.
I agree that as a two-stage you're going to need good eyes!

Edit: BTW nice job on the conversion!

 

[Bowman]

I am Gnome-less, so no knowledge of structural integrity of that particular bird..

My daughters experience with that is it is a pretty tough little bird.
Most noticeable is a little bit of charring where ejection gasses escape past the front tab of the motor retainer.
But that is after 40+ flights and several years.

 

[smstachwick]

Also, while 10 to 1 length to diameter rule works for drag coefficient (meaning going over 10 to 1 doesn’t slow the Rocket down much more), VISIBILITY is pretty much directly related to length, especially if there are bushes or tall grass. So go with the longest streamer that EASILY ejects. It will help with visibility on descent AND on the ground.

I hadn’t considered this, but the sustainer is brand new and I’ve got the stock streamer in it. It’s already a challenge to pack. Not impossible, just challenging,

Edit: BTW nice job on the conversion!

Thank you!

I’d been planning this for some time, but the original airframe getting bent really changed things. I was originally hoping to have a longer booster and keep the aft end of the hook more or less stock, but hey, what can you do? You can’t fly with a bent booster!

I do hope the thing works. The additional failure modes involving retention, separation, and ignition have me pretty nervous.

 

[smstachwick]

I found that missing booster motor. It had somehow gotten into the big Husky tool chest. Best guess is that I was looking for a tool of some kind with the motor in my hand and I dropped it in without realizing it.

 

[BABAR]

An easy way to do the conversion would be to use the cut-off piece of the body tube of the booster as an EXTENSION to lengthen the sustainer. Not sure if the kit includes a “pusher tube” for putting in an engine block (or motor-block, depending on how you lean on another thread), if so that would serve as a coupler. Would greatly increase your space for recovery gear, maybe even put in a baffle, Would increase stability. Might need to roll the streamer twice, one segment in front of the other.

 

[smstachwick]

An easy way to do the conversion would be to use the cut-off piece of the body tube of the booster as an EXTENSION to lengthen the sustainer. Not sure if the kit includes a “pusher tube” for putting in an engine block (or motor-block, depending on how you lean on another thread), if so that would serve as a coupler. Would greatly increase your space for recovery gear, maybe even put in a baffle, Would increase stability. Might need to roll the streamer twice, one segment in front of the other.

There is no pusher tube in this one, as there is no motor block. The forward portion of the motor hook serves this purpose. I bet if I really wanted to I could cut part of the scrap booster tube and reduce the diameter to create a coupler. I think I’ll save that until after ROCstock though (Holtville Havoc has sadly been cancelled). I mainly just want to see if the thing is flyable or recoverable at all.

Regarding the internals, I’m entirely unfamiliar with baffle systems. I’d want to try my hand at a kit or set of plans that incorporate them before creating one myself. I might try the dual roll idea, though. It can be tricky to get everything in the BT-5 tube, and I already do a variation of this where I wrap the streamer just forward or aft of the knot.

Another thing I may decide to do is use a “hybrid” wadding system: dog barf on top of a single sheet of Estes fireproof toilet paper so that I can blow it down into place but still not litter scorched TP downrange.

 

[Arnie]

Might be a nice model for the Nartrek Bronze streamer duration flight

 

[smstachwick]

I can’t believe I didn’t think to time it when I flew it at ROCstock. Summary here:

ROCstock was absolutely awesome! I got far too much flying done over the course of the 3-day event to do a play-by-play report, but here is a quick summary.:

• My Super Gnome made five flights: three successful flights in two-stage configuration, along with one successful flight in a single-stage configuration and an unsuccessful two-stage flight in which the sustainer failed to light. This rocket attracted some attention from a few attendees who had seen it here on TRF and wanted more information on how I made it and how it works.
• My rebuilt Phantom made all of its six flights with a cardstock liner inserted in the body tube to preserve its transparency. This included my first ever night flight, with a blinky installed in the nose. This flight was the one that did it in; I have since replaced it with an Estes Generic E2X, although I’ve held onto the nose and blinky just in case I ever want to do a night flight on that one.
• I intended to enter my stock Estes Goblin reissue in the contest for Goblin derivatives, clones, and upscales. The guy at the check-in booth just laughed at me. I think it ended up flying three times through the event, ending its weekend with a tangled chute and two cracked fins.
• My Hi-Flier XL made two successful flights on the reinstalled motor mount, but while I was loading it up for a third flight, the forward centering ring failed from damage sustained during its splashdown at Fiesta Island last month. I purchased a new mount kit from Discount Rocketry and I plan to install it soon.
• My Star Orbiter made not one but TWO successful flights on E23s, my first flights with any kind of reloadable. I have since cleaned out the hardware and ordered Aerotech E16W reloads through AMW.
• I tried my hand at working the launch control system and PA system, hitting the button for rockets up to M power and helping a couple of flyers make their certification flights.

Overall, fun weekend. I look forward to joining ROC in the future, that was a great event. I take my hat off to all of those who made that possible.

I lost the sustainer on Tuesday too.

I’ve got a couple of Star Troopers in the mail that I plan to configure similarly. I think the booster on that one will be far prettier, seeing that I get to choose the length of the tube instead of being forced to cut at a bend.

 

[Rocketjunkie]

I cheat. I make 13 mm motors including a full D40 (14 lb. thrust for .4 sec.). It will fit a Gnome. The fins survive...Once Flown many of these in Gnomes. Get them back somewhat less than 1/2 the time.

 

[smstachwick]

I cheat. I make 13 mm motors including a full D40 (14 lb. thrust for .4 sec.). It will fit a Gnome. The fins survive...Once Flown many of these in Gnomes. Get them back somewhat less than 1/2 the time.
View attachment 490783

Wow, that really is cheating! Look badass as all hell though.