D to C engine adapter

I have a rocket that I'm upscaling, and the motor mount is for a 24mm E size, but I only ever plan on flying it with a D so I'll always use the orange spacer for D engines.

However, for my first flight I'm seriously considering letting it go with only a C engine to test how well it flies. But... the 18mm C engine won't fit well into the 24mm mount.

When painting the rocket I've used a dowel that has a spent 18mm engine on the end, and then a spent 24mm engine over that, which holds the rocket really well. It occurred to me that maybe I could use a spent E engine, nozzle end up, as an adapter to fly on a C engine. Maybe I'd have to drill out the nozzle to open it up enough to allow the ejection charge to blow into the body correctly.

Has anyone ever done this, and does it work well? Or is there a better adapter to use in this situation?

Whatever method you use... the smaller "C" engine must be positively retained.

That concept should work fine. Definately drill out the nozzle of the spent casing. Use a small cross-section of a spent C casing as a block in the spent E casing, if you want to keep doing this. You're gonna have to figure out how to retain the C engine in the E casing (friction fit? Glue it in it it's just a one time deal). Make sure that the rocket is not too heavy for a C engine. If it is getting marginal on weight-to-thrust ratio, maybe try a D casing and an orange Estes D-E spacer, and drill some lightening holes in the sides of the spent D casing.

Why not just use an Estes C11, which is the same physical size as the D12, 24mm x 2.75" long?

tmacklin said:

Why not just use an Estes C11, which is the same physical size as the D12, 24mm x 2.75" long?

Click to expand...

Beat me to it!!! The C11 is one of my favorite Motors!!! I get about half the altitude of a D12 in my smaller 24mm Birds.

tmacklin said:

Why not just use an Estes C11, which is the same physical size as the D12, 24mm x 2.75" long?

Click to expand...

TopRamen said:

Beat me to it!!! The C11 is one of my favorite Motors!!! I get about half the altitude of a D12 in my smaller 24mm Birds.

Click to expand...

Totally ninja'ed...TWICE!

If it is heavy enough to need a D in the first place, the C11 will give it a nice kick off the pad.

Man, if only they had had C11's when I was a kid...then again, I wouldn't have been able to afford them...

455 Buick said:

You're gonna have to figure out how to retain the C engine in the E casing (friction fit? Glue it in it it's just a one time deal).

Click to expand...

Excellent! I'll glue it in there, it's definitely a one time deal. Either it flies okay and I'll use D from now on, or it curves over and augers in under power and it makes a big mess and I set it on fire.

455 Buick said:

Make sure that the rocket is not too heavy for a C engine.

Click to expand...

That's something I don't even know how to guess on. The original rocket flies really high on a C6 so a 1.5x upscale should fly high enough on a C6 for me to know that it's okay. From then on I'll go with a D.

tmacklin said:

Why not just use an Estes C11, which is the same physical size as the D12, 24mm x 2.75" long?

Click to expand...

Mostly because I want to use a C6 (which I didn't mention earlier) to gauge how this upscale behaves against the known behavior of the original on a C6. Also because I didn't know about the C11.


There's always the chance that it'll fly great on a C6 and I won't want to fly it on a D most of the time, in which case I'll go with the plastic engine adapter linked in post #2 by Jeff2space.

jeff2space said:

https://www.estesrockets.com/rockets/accessories/302317-engine-adapters-standard-to-d

Click to expand...

Those little guys work great!

tmacklin said:

Why not just use an Estes C11, which is the same physical size as the D12, 24mm x 2.75" long?

Click to expand...

I always forget about these.. lol

455 Buick said:

That concept should work fine. Definately drill out the nozzle of the spent casing. Use a small cross-section of a spent C casing as a block in the spent E casing, if you want to keep doing this. You're gonna have to figure out how to retain the C engine in the E casing (friction fit? Glue it in it it's just a one time deal). Make sure that the rocket is not too heavy for a C engine. If it is getting marginal on weight-to-thrust ratio, maybe try a D casing and an orange Estes D-E spacer, and drill some lightening holes in the sides of the spent D casing.

Click to expand...

Weigh your rocket! A C6 can safely lift 4.0 oz. and a C11 6.0 oz. These max lift-off weights are the combined total weight of the rocket and motor.

Jerome

Quick and easy 18-24mm adapter w/retention

Well I would post a picture, EXCEPT THE FORUM SOFTWARE WON'T LET ME.

I've posted dozens of pictures but now I can't. I select the picture to upload, but the "upload picture" button never appears. Same in Quick Reply and Go Advanced. Firefox and Chrome.

Anyway, it's made from a short piece of BT20 and a 1/4" and 1/2" pieces of an old 24mm BP motor casing. I've got two - a short one the length of the D and C motors, and a longer one the length of the E motors.

455 Buick said:

That concept should work fine. Definately drill out the nozzle of the spent casing. Use a small cross-section of a spent C casing as a block in the spent E casing, if you want to keep doing this.

Click to expand...

This is exactly what I've done, though I only used a D casing (the rocket doesn't have the extended mount for an E). I don't drill the nozzle out, though. Squashing the rear end of the casing causes the nozzle to crumble and fall out, then I just squash it again to put it back into shape. Quick and easy, especially since the squashing just involves putting the empty casing onto a flat rock and stomping on it.

You're gonna have to figure out how to retain the C engine in the E casing (friction fit? Glue it in it it's just a one time deal). Make sure that the rocket is not too heavy for a C engine.

Click to expand...

Friction fit works for me. The warning about not being too heavy is definitely important - a rocket with enough nose weight to be safe with a D12 may very well be too heavy for a C6.

You can also do the same to an expended B or C casing to turn it into a 13mm/18mm adaptor so mini-motors can be used in a model with a standard A/B/C mount.

I use a 24mm/18mm adaptor made with a 2.75" long piece of BT-20 and 3- CR-2050 centering rings with a standard spring retainer hook.
These little adaptors work just fine and are transferable to whatever model I wish to use 18mm motors in.
I usually have one of two with me in my range box.

Micromeister said:

I use a 24mm/18mm adaptor made with a 2.75" long piece of BT-20 and 3- CR-2050 centering rings with a standard spring retainer hook.
These little adaptors work just fine and are transferable to whatever model I wish to use 18mm motors in.
I usually have one of two with me in my range box.

Click to expand...

Pretty nifty! If I decide I want to be able to keep flying this rocket on C motors in the future I'll make a couple of those. Thanks for sharing!

But for the first one I think I'll just glue a C inside a spent E after I pull out the nozzle. That's a good enough one shot solution.

Have you thought about the extra weight of the entire E case versus just using rings cut from the E case? Two rings cut from the E case would hold the C well enough and wouldn't add as much weight to the rocket. Scuff up the case well and wood glue the rings to the C case.

scsager said:

Whatever method you use... the smaller "C" engine must be positively retained.

Click to expand...

Why? I use spent casings as adapters often. Masking tape friction fit works fine.

I personally just buy the Estes Adapters. Cheap, easy to use, and great for stagers too. No tape, glue, or building an adapter needed.

I've taken a Long Tom which can take D to E staging (both stages modified to take 24mm), and have used the adapters to convert it to a B6-0 / 1/2A3-4T stage (yep, nested adapters in the second stage).

The nice thing about the Estes Adapters is that because they have a 'notch' for the engine hook, the smaller 18mm motor does not 'stick' out in either direction. Great for staging in that the engines don't cause a mismatch between them...essential for 'gap' staging where the lower stage motor tube butts right against the upper stage engine.

FC

tmacklin said:

Why not just use an Estes C11, which is the same physical size as the D12, 24mm x 2.75" long?

Click to expand...

I said earlier that I didn't know about the C11. And if asked about it before you told me I would have said that all C engines were the same size. I just don't have enough experience with engine selection and familiarity with the thrust provided by the different engines.

However, last night I was cleaning up my build area (I can explain what that phrase means to anyone that is unfamiliar, just PM me) and had about a dozen packs of engines I needed to open and put in my range box. When I was doing this I saw 4 of the C11 engines that were in my range box already - I must have bought them a long time ago for some reason and haven't used them yet.

I just stood there and smiled. So I guess I'll be launching the new rocket on a C11 for it's first flight after all (unless it's too heavy as mentioned at the bottom of post #9. Max weights for each motor is something else I need to get familiar with).

FastCargo said:

I personally just buy the Estes Adapters. Cheap, easy to use, and great for stagers too.

Click to expand...

These are good reasons, but...

FastCargo said:

No tape, glue, or building an adapter needed.

Click to expand...

You say this like it's a negative. I would MUCH rather build an adapter myself, now that I know how, than buy one. Heck, I'd pay 3 times the cost of buying one to get the materials if I can build it myself.

Mushtang said:

These are good reasons, but...

You say this like it's a negative. I would MUCH rather build an adapter myself, now that I know how, than buy one. Heck, I'd pay 3 times the cost of buying one to get the materials if I can build it myself.

Click to expand...

I can understand that as a builder. Having said that, I have built a couple of adapters myself, and to me, after it was all said and done, it wasn't worth the time and effort.

For me, it was kind of like doing my own oil changes. In the beginning, it was to save money and of course knowing how to do it. Familiarity with our vehicles and all that. However, over time, I wasn't going to learn any more about cars than I already knew (which is a lot), and the cost + time curve continued to rise while the cost + time curve of taking them to a oil change station continued to fall. At some point, the curves crossed and I stopped doing it myself. I consider oil changes, and building adapters like I consider paperwork as a pilot...it may be necessary to do, but if I can outsource it, I will because it doesn't contribute to my enjoyment.

But, that's my approach, others of course feel differently, and that's okay. Nice thing about this hobby is that as long it is safe and legal, there is no wrong way to do it, no matter what self imposed gatekeepers may think.

Have fun!

FC

You're gonna' like the C11!!!

JeromeK99 said:

Weigh your rocket! A C6 can safely lift 4.0 oz. and a C11 6.0 oz. These max lift-off weights are the combined total weight of the rocket and motor.

Click to expand...

Welllllll...... this whole thread may have been for nothing. I just weighed what I have so far, and that doesn't include the laundry, engine, or some nose weight that I know I'll need to add, and I'm already between 6 and 7 oz. I'm guessing I'll need a D engine anyway.

But thanks to everybody for all the information on the adapter. I think I'll build a couple and have them in my range box just in case.

Okay, it wasn't for nothing. I learned about Max lift off weights, and how to build an adapter. Woo-HOO!

Here's my Fiberglassed 24mm Patriot on a C11-3
It Weighs 6oz. without motors:

[video=youtube;Rm5Z3X47B_M]https://www.youtube.com/watch?v=Rm5Z3X47B_M[/video]

TopRamen said:

Here's my Fiberglassed 24mm Patriot on a C11-3
It Weighs 6oz. without motors:

Click to expand...

Well you're clearly beyond the guidelines here and it seems to have flown just fine. Now I'm back to being confused about what I should fly it with.

First thing is to finish the rocket and get a final weight. Waiting on USPS to deliver some nosecones that are STILL showing on the tracking page as scheduled to be delivered yesterday.

Mushtang said:

Well you're clearly beyond the guidelines here and it seems to have flown just fine. Now I'm back to being confused about what I should fly it with.

First thing is to finish the rocket and get a final weight. Waiting on USPS to deliver some nosecones that are STILL showing on the tracking page as scheduled to be delivered yesterday.

Click to expand...

Guidelines are just that, guidelines. That's the point I was trying to illustrate.
There are folks here that never even fly their rockets because the Sims and Guidelines make them think they won't fly safely.

Yesterday I made up this adapter for my Minimum Diameter Alpha 24mm. It sims to 800+Ft. on a C11, so I wanted to start her out on a diet of 18mm B motors. It actually sims higher by a hundred + ft. on a C6 than it does on the C11.
anyhow, I can also use this adapter on my MD Crossfire too.
CG is still good, I checked it.

Guidelines are just that. I regularly fly rockets I adapt down because my field is pretty small. I usually OR them just to make sure I'm not doing anything too crazy. Like the B6-0 / 1/2A3-4T two stage Long Tom. Or a B6-2 Stormcaster or a C6-3 QCC Explorer or Vagabond. All fly just fine on those engines, even though none of them are sized for them.

FC

TopRamen said:

Here's my Fiberglassed 24mm Patriot on a C11-3
It Weighs 6oz. without motors:

Click to expand...

I launched a Maxi Alpha 3 on a C11—I think it sim-ed to 120 feet (using OpenRocket), my Jolly Logic II altimeter said it hit 84 feet — the parachute deployed ok, safe recovery, no problems. I think if I would have used a 1/4 inch rod, it would have launched straighter and gotten closer to the 120, I remember seeing go off at more of an angle than I was expecting, so the rod may have whipped a little.…

Estes says it has an estimated weight of 6.6 ounces, not sure how much glue I used…oh, and I had a baffle installed and the altimeter, so it was probably closer to 7 ounces.

Having said that, that is probably the heaviest you would want to go with a C11. Unless you are willing to risk your rocket.

A Maxi Alpha 3 on a C11-3 is very amusing.....up to around 100 feet - pop the 'chute - land right next to the pad.... A great big demo bird for a small field.