Mini Engine Rockets

[SolarYellow]

That Tempest looks cool. Just eyeballing it, you wouldn't have to shorten the booster much to eliminate the gap with a C6-0 in BT-20.

 

[Lutin]

Bernard was suggesting the Estes Checkmate a couple days ago, here's a beautiful shot of he's so beautiful Checkmate much better yellow on yellow.

 

[mh9162013]

Bernard was suggesting the Estes Checkmate a couple days ago, here a beautiful shot of he's so beautiful Checkmate much better yellow on yellow.View attachment 571897 View attachment 571897

Great photos!

Did you take them? If so, what are the details of the camera equipment and settings?

 

[Lutin]

Great photos!

Did you take them? If so, what are the details of the camera equipment and settings?

Sorry found on FB National Association of Rocketry. Sorry tock out the names

​

Bernard Cawley's Estes Checkmate caught right at staging. Launch held today at South Seattle Community College as part of the Amelia's Aeroclub events sponsored by the Museum of Flight, Aurora Flight Sciences, and the NAR in Seattle. Nikon D5, 70-200mm, f2.8, 1/8000, ISO 200. More photos to follow!

 

[BEC]

Great photos!

Did you take them? If so, what are the details of the camera equipment and settings?

I did not take that picture. As you can see from the “Tahoma Photography” mark in the lower right, this was taken by Jim Wilkerson, Boeing production test pilot and NAR board member. I do not know the details of his setup, I just know he has quite a bit of gear with long lenses. This shot was taken at a small launch for a Museum of Flight program at a school field fairly near the museum. The unusual thing about it is that the booster motor was a long OOP 1/2A3-0T so it staged about 50 feet up. That’s the best black powder direct staging picture I’ve ever seen.

That picture is of my first Checkmate. I am currently on my third. The occasional upper stage failing to light over a hard surface after an A10-0T boost is hard on body tubes. The next two have one blue fin on the booster and sustainer, so that it’s more like (but not quite) the face card scheme. My models are also modified to make the top 1 1/2 inches a payload section for a small altimeter. That’s why the line above the upper checkerboard pattern.

BTW, I was about to order another Checkmate from AC Supply, and clearly they are having a run on Estes stuff due to this bit about minimum advertised prices….and they’re gone. Since it is not in the 2023 catalog, I don’t know where one could get one now that AC Supply is not showing it anymore. It would be fairly easy to clone, though — there are no unique parts in it.

AC is also no longer showing the A10 booster motors (or really very many Estes motors in general).

Added: I’ve been able to find Checkmate kits at eRockets, jonrocket and FlightSketch so far. Only eRockets says how many they have, and they currently show eight.

Further added: I've ordered one each from FlightSketch (who show one more in stock) and jonrocket (no idea of stock level there). So the eight at eRockets are still there. It's not in the 2023 catalog as mentioned before, but Estes shows it on their site, so I expect the price will go up to $14.99 (from ~$11) tomorrow because of this minimum advertised price business discussed elsewhere.

 

[mbeels]

That’s the best black powder direct staging picture I’ve ever seen.

Wow. Yeah.

 

[Bruiser]

That is an awesome rocket! And holy cow, what a photograph!

Looks like a two-stage is in the works for Bruiser Design Studio I shrunk my Tempest and redesigned it a bit and it certainly looks do-able as a C6-0 booster to a 13mm sustainer. I'm going with the C6-0 as that is the only booster motor that HL carries anymore. HL equals easy to get.

Am I going to need some sort of "shelf" inside the body tube of the Black Brant I am working on to keep the streamer and shock cord close to the nose? There's about 7 inches of free space inside the body tube...

Thanks,
-Bob

 

[bjphoenix]

I have a couple of Baby Bertha's. They are both Goonies. I launched the Patriot with an A8-5. It went about a hundred feet, arced over and came back to the ground and made a thump. Then the chute popped out. No real damage, it's pretty sturdy and heavy due to nose weight. Guess the -5 was a bit too long

So the retention hook... I did some math and there is only a gap of .083 between the outside of a BT-5 and the inside of a BT-20. The hook material is about .031 thick so that leaves just over 1/32 of an inch for the hook to flex. I only had the hook sticking out 1/2 inch from the motor mount. I was getting just over a 1/16th of an inch flex at the end of the hook. I could have trimmed the hook to let the motor pass but I was not confident it would really hold the motor in come ejection time. Don't really like the tape method and have never used it before but it seemed the "go-to" for this rocket. I am going to keep my eyes open for some thinner. springier (?) metal to make hooks out of for future rockets

I would suggest running Open Rocket on that BB Patriot. I've flown my stock BB on B6-4 and I've seen other people fly them stock on A8-3. If you added nose weight that is likely a problem.

For the retention hook- check to see how much slop there is in the motor fit. If the hook is not moving much sometimes the motor can angle over just a bit and that helps. You could build it with the engine and hook projecting out a little bit farther, or cut a small notch in the end of the main tube to get a little more bending in the hook. If you have a smaller hook over the back end of the motor you can wrap a strip of tape around the back end of the motor to hold the hook tight against the motor and it can hold the motor even with a small hook.

 

[BEC]

That is an awesome rocket! And holy cow, what a photograph!

Jim Wilkerson takes lots of amazing rocket pictures, as well as other subjects. Thanks for the compliment on the model.

Am I going to need some sort of "shelf" inside the body tube of the Black Brant I am working on to keep the streamer and shock cord close to the nose? There's about 7 inches of free space inside the body tube...

Qualman Rocketry has some shelves for this purpose in his product line.

Thanks,
-Bob

 

[Bruiser]

I did think about cutting a channel in the body tube to allow the hook to bend more but it's a scale rocket and I just couldn't bring myself to do it

The Baby Bertha required lots of nose weight because of the small fins. The A8-5 was just to small with too long of a delay.

I'll check out Qualman Rocketry. Thanks for the lead.

I'm gonna start a new thread for the rocket build over here: https://www.rocketryforum.com/threads/black-brant-vc-for-mini-motors.179141/

-Bob

 

[Lutin]

Just a heads-up, Aerospace Specialty Products (https://www.asp-rocketry.com/) has some very nice 13 mm version rockets and some are on special this month.
Paul

​

 

[BEC]

Just a hand-up, Aerospace Specialty Products (https://www.asp-rocketry.com/) has some very nice 13 mm version rockets and some are on special this month.
Paul

​

That is true. Their little BT-50-based V2 is a cool model which works pretty well.


Added: also, the Checkmate is back on the AC Supply web site, but at MSRP, of course ($14.99).

 

[Bruiser]

I really missed the boat on this MAP thing. I bought a few motors at HL today just in case their prices jump too. Was really there to look at Createx paint. I think I need to start painting with an airbrush for models at this size. I've had the airbrush for years but it has sat un-used all this time.

I was aware of the ASP kits. I've been eye-balling their 29mm Sandia Sandhawk for some time. If it had a printed antenna section like the Rocketarium kit does I would have one in my stash. If the Rocketarium kit was slightly bigger I would have one of them . Anyway only about half of the 13mm kits are BT-20 sized. The other half are BT-5 and that is just too small for me. I have a hard time seeing details on the BT-20 sized rockets.

Thanks for the tips,
-Bob

 

[Charles_McG]

I can’t find pics of all my Minis. But here’s one.

 

[Bruiser]

What does everyone due for recovery? Estes included a 18 inch long piece of 1/8th rubber and a 12 inch long streamer with the Hi-Flyer. They have you attach the shock cord to the body tube via the tri-fold paper method and tie it to the nose cone. They have you tape the streamer to the 1/8th inch rubber. Is that pretty much the standard for rockets this size?

Also, a question about the Checkmate. I see the booster uses a coupler to connect with the sustainer. It looks like it goes in to the sustainer about 1/2". Is that about right? Also, how is the sustainer motor held in place?

Thanks,
-Bob

 

[mh9162013]

What does everyone due for recovery? Estes included a 18 inch long piece of 1/8th rubber and a 12 inch long streamer with the Hi-Flyer. They have you attach the shock cord to the body tube via the tri-fold paper method and tie it to the nose cone. They have you tape the streamer to the 1/8th inch rubber. Is that pretty much the standard for rockets this size?

I avoid the teabag/tri-fold method because I like to avoid putting anything inside the BT-20 tube that might hinder full ejection of the parachute; it's a small enough tube anyways.

I will use a hybrid shock cord, with the Kevlar portion attaching to the MMT area, either to a removable baffle or to a permanently installed baffle (or just above it, tied to a thrust ring). The Kevlar is long enough to extend pass the top of the main body tube. From there, I attach the rubberized/elastic portion of the shock cord. This is then attached to the nose cone or payload bay.

The rubber part of the shock cord is designed to be replaced due to wear and tear. If the Kevlar is attached to a removable baffle, it's easily inspected/replaced. If it's permanently attached to a baffle or thrust ring, then I'll take extra steps to protect the Kevlar, such as using a thicker piece and/or covering the knotted portion at the attachment point with some heat shrink tubing.

As for recovery device, I usually use a 7-8 inch Mylar parachute. These pack down really small so there's no space issue in a BT-20 tube. I'm thinking about trying a streamer, but I'm not sure if my rockets will survive the fall. This is because I build my rockets heavy (my typical BT-20 rocket easily exceeds 25 grams in total weight, but not counting the engine).

 

[Charles_McG]

Streamer for recovery. I use a kevlar thread tied and glued just behind the forward motor mount centering ring, running underneath it, tied to the rubber shock cord before it gets to the top of the body tube. I pull the thread through the motor tube, tie on the shock cord, then push it all back through. I think the trifold makes a lump on the body tube for recovery kit to get hung up on.

Also, I'm weird in that I don't put in an engine block, and If I use a hook, and bend the forward end back wards. I use a narrow tape thrust ring. This is following Wildman's Second Law (no engine blocks!) and because I have a stash of 13mm Centuri Bs that I fly under the expired motor program.

 

[BEC]

What does everyone due for recovery? Estes included a 18 inch long piece of 1/8th rubber and a 12 inch long streamer with the Hi-Flyer. They have you attach the shock cord to the body tube via the tri-fold paper method and tie it to the nose cone. They have you tape the streamer to the 1/8th inch rubber. Is that pretty much the standard for rockets this size?

Also, a question about the Checkmate. I see the booster uses a coupler to connect with the sustainer. It looks like it goes in to the sustainer about 1/2". Is that about right? Also, how is the sustainer motor held in place?

Thanks,
-Bob

I generally use the stock recovery system with some added kevlar put in a tri-fold in the indicated location. The kit's shock cord then tied to that and the streamer taped as indicated in the instructions. I put a about half an inch of heat-shrink tubing on the Kevlar to protect it from rubbing on the tube edge before tying on the rubber shock cord. However, I've had enough situations where the Kevlar wore through just beyond where I protect it that I may go back to all-rubber shock cords in future builds. I just got a 1/2 lb. of FAI Tan Sport rubber in 3/32 inch width that looks to be just the ticket for models this size (BT-20-based).

Both motors in Checkmate are friction fit and the are taped to one another in the usual long-standing direct-staging method. And yes, the coupler protrudes halfway into the base of the sustainer.

Checkmate comes with a longer streamer than Hi-Flyer you mention. More like two feet or a bit more.

 

[SolarYellow]

I'm thinking about using E6000 on the tri-fold to hold the Kevlar. It dries flexible, so it shouldn't create as much of a weak spot right at the end of where the glue saturates the fibers of the Kevlar.

 

[BEC]

Interesting idea. Might be worth a try as right at the tri-fold is another place I have failures. I normally do tri-folds with Titebond or Elmer’s or Allene’s.

 

[Bruiser]

"Both motors in Checkmate are friction fit and the are taped to one another in the usual long-standing direct-staging method"

I am thinking this thru. So you tape the motors together then slide them into the sustainer where it is friction fit, then you slide the booster fine assembly up the booster engine until the coupler is seated into the sustainer? When the sustainer ignites it blows the booster motor away along with the booster fin can assy because of the friction fit?

For the friction fit do you use a small piece of masking tape on the side of the motor?

-Bob

 

[smstachwick]

"Both motors in Checkmate are friction fit and the are taped to one another in the usual long-standing direct-staging method"

I am thinking this thru. So you tape the motors together then slide them into the sustainer where it is friction fit, then you slide the booster fine assembly up the booster engine until the coupler is seated into the sustainer? When the sustainer ignites it blows the booster motor away along with the booster fin can assy because of the friction fit?

That’s the idea.

For the friction fit do you use a small piece of masking tape on the side of the motor?

That’s also the idea. In my case it’s often more like a wrap around the tube (or several)

If the motor is tight enough that you’re wondering how you’ll ever get it out, it’s perfect. They tend to loosen up a bit and sometimes even fall out of the booster once they cool off, so the sustainer one will be easy to remove.

For boosters, a lot of people will use a thrust ring mounted at the REAR so that the motor can’t kick out at staging. If that happens you’ll typically cook your booster.

 

[BEC]

If the motor is tight enough that you’re wondering how you’ll ever get it out, it’s perfect. They tend to loosen up a bit and sometimes even fall out of the booster once they cool off, so the sustainer one will be easy to remove.

Yes, exactly. I've come to depend on this loosening effect.

It also helps to NOT have a bunch of smeared glue from the motor block installation inside the motor mount tube, as heat can soften it, making getting the motor out later challenging.

For boosters, a lot of people will use a thrust ring mounted at the REAR so that the motor can’t kick out at staging. If that happens you’ll typically cook your booster.

The Checkmate does have one of those motor blocks at the back of the booster. It makes getting an igniter in a little harder and after about 15 flights it gets pretty badly cooked. But enough of it remains for it to do its job even if it gets ugly. This approach negates the tape wrap around tube and motor approach, though.

 

[BEC]

"Both motors in Checkmate are friction fit and the are taped to one another in the usual long-standing direct-staging method"

I am thinking this thru. So you tape the motors together then slide them into the sustainer where it is friction fit, then you slide the booster fine assembly up the booster engine until the coupler is seated into the sustainer? When the sustainer ignites it blows the booster motor away along with the booster fin can assy because of the friction fit?

For the friction fit do you use a small piece of masking tape on the side of the motor?

-Bob

My goodness...you need to read TR-2 (from 1963). http://www.ninfinger.org/rockets/EstesTR2.pdf

The Checkmate is set up as in figure 9C.

 

[Bruiser]

I've never seen that before but it's not quite 9C because the Checkmate has a coupler like figure 6. Figure six is close to the style I am use to seeing like with the pro series booster.

-Bob

 

[BEC]

Well OK — figure 6 with an aft motor block like 9C.

The Pro Series booster (as well as the accessory Booster-55 and -60) have positive motor retention. They also are gap-staging which is beyond the scope of TR-2.

Checkmate (and the TK-45 Beta) as well as Farside, Apogee II, the current Sterling Silver/Epic II twins, the Apache II and a bunch of others are direct tape-the-motors-together stagers.

 

[smstachwick]

LOL at the BT-50 being a larger tube

 

[Bruiser]

I've read, and re-read all the replies regarding the recovery err, system and I think I've developed this plan based upon the consensus of the replies.

First I'll use Kevlar attached to a ply shelf in the body tube. The Kevlar will transition to elastic outside of the body tube. A streamer will be attached to the elastic a few inches before the nose cone.

This is the ply shelf I made up last night. It is inserted into a piece of tubing in this photo for a reference to the size of the openings for the ejections gases to pass thru. Do they seem large enough? If not, I think I can make them a little larger, but not too much. I'm thinking it will be 4.5 inches from the nose cone.


There will be a screw eye epoxied into the ply shelf. I have both 250 and 380lb Kevlar. I've got to decide which weight but I am thinking a single strand with a loop at each end for easier replacement if needed. I'm thinking about 8 inches long or so.

Then it will transition to a 16" piece of shock cord. The 12 inch long streamer will attach to the shock cord about 4 inches from the nose cone.

Sound good?
-Bob

 

[mh9162013]

I've read, and re-read all the replies regarding the recovery err, system and I think I've developed this plan based upon the consensus of the replies.

First I'll use Kevlar attached to a ply shelf in the body tube. The Kevlar will transition to elastic outside of the body tube. A streamer will be attached to the elastic a few inches before the nose cone.

This is the ply shelf I made up last night. It is inserted into a piece of tubing in this photo for a reference to the size of the openings for the ejections gases to pass thru. Do they seem large enough? If not, I think I can make them a little larger, but not too much. I'm thinking it will be 4.5 inches from the nose cone.
View attachment 574720

There will be a screw eye epoxied into the ply shelf. I have both 250 and 380lb Kevlar. I've got to decide which weight but I am thinking a single strand with a loop at each end for easier replacement if needed. I'm thinking about 8 inches long or so.

Then it will transition to a 16" piece of shock cord. The 12 inch long streamer will attach to the shock cord about 4 inches from the nose cone.

Sound good?
-Bob

The openings of the ply shelf will probably be sufficient to allow ejection gasses through, but I'd make them large enough so they equal at least 40% of the area of the overall inner diameter of the main body tube. That being said, I'm curious as why you're going to install a ply shelf and not just go ahead and put in a baffle. Is it because you don't have the vertical/length-wise space to do so? Also, regardless of whether you use a "shelf" or baffle, the resistance they impose on ejection gasses may put additional stress on the airframe. This may or may not have an effect on the overall life of the rocket, especially the motor retention system (or make it more likely the motor casing will be ejected out the back if using friction fit).

 

[aerostadt]

I launched a J & H Aerospace Boost Glider "Wind Lance" last Saturday on an A3-2. I had a feeling that it might perform well. Unfortunately, it performed too well. I could see it circling around way up there, but I took my eyes off of it for a second and I lost it. I talked to 2 other rocketeers later and they told me it caught a thermal. They watched it until it was gone, never to be seen again. Fortunately, my wife found the pop pod and it was intact. It landed not too far away. I can't remember for sure, but I think I launched a similar model last Fall with a longer time delay and it spiraled in. This is definitely the right time delay.