GLR Mariah 38 - Block 3 Build

[SinfulDarkLord]

Here is the final step to the build of the breadbox/shotgun tube. Please note that I have not yet attached the chute and I plan on using a parachute swivel even though I was told that it was not needed. Pictures are in order. The final step that needs to be dealt with is the installation of the Shock Cord Hardpoint Anchor. Although I do not plan on using it. I will be posting some pictures showing how it is glued in place.

1. Glued Piston and Charge Cap to Kevlar shock cord.
2. Completeded breadbox/shotgun tube assembly.

[Fe Dude]

I like the new method of rigging the chute. The previous method having the shock cord and chute packed into the shotgun tube made extracting a packed chute a bear.

[SinfulDarkLord]

Yes it is better this way I most agree. The hard part actually is folding the chute. It slips too much and unfolds so you gotta keep a tight grip on it when you fold it lol. I love this parachute its awesome.

[SinfulDarkLord]

Finally at long last the last step in the Mariah 38 build. I didnt glue it in there because I will be using a different method. If you are going to glue it apply JB Weld into the inside of the booster section of the Mariah 38 and with the 10.5 inch glue stick push it down in there. I would recommend using a 15 inch long stick as to achieve more space. Do not go more than 15 inches otherwise you may not be able to use longer casings. Here are the pictures to the final step in the build.

1. Attach Kevlar Shock Cord to the Hardpoint Anchor
2. Glue into booster section with JB Weld

[SinfulDarkLord]

Hello Members I went ahead and did a little video describing how the ejection and wiring goes to the breadbox/shotgun tube. In the video I made a mistake and accidently called the breadbox bay the shotgun bay lol. Also I stumbled a little so sorry about that. Enjoy

[SinfulDarkLord]

Well Folks here is the Mariah 38 Completed and Painted nicely. I hope you all have enjoyed this forum. Thanks to all the subcribers. Also thank you Giant Leap Rocketry for an amazing kit that you guys made.

[Fe Dude]

That is mighty fine, now I'm going to need to get another one...

[SinfulDarkLord]

I am going to get me a second myself as well Fe Dude. This model is just great that I want to get a second one.

[Estimado]

I bought a Mariah 38 when they first came out and I set the kit aside. I would like to build it now. How different are the new kits and instructions? Does the new kit contain different materials? Can anyone send me the updated instructions?

[flynfrog]

I bought a Mariah 38 when they first came out and I set the kit aside. I would like to build it now. How different are the new kits and instructions? Does the new kit contain different materials? Can anyone send me the updated instructions?

The main thing is the switch to piston deployment there is a thread here outlining it.

I found an a tolerance stack issue in the breadbox you need to not double up the rings that are inside the bread box it can cause it to bind. Sorry I don't have a picture but the rings that prevent the outer tube of the bread box form going to far aft or fwd on the 54 called out for two rings to be bonded around smaller rings. If these are off the bread box will get tight at one point in the turn and bind.

[freddiejojo]

Hi, the issue you mentioned is on the M54. I have fixed that problem and soon there will be a new Mariah 54 that will include the same upgrades as the Block 3 version of the Mariah 38.

Thank you,

Kent/GLR

[BearMan]

I bought a Mariah 38 when they first came out and I set the kit aside. I would like to build it now. How different are the new kits and instructions? Does the new kit contain different materials? Can anyone send me the updated instructions?

I am sure if you contact Kent at GLR he would be happy to send you the updated instructions ;-)

Last summer I posted the changes I made to my M54 kit and Kent has updated the kit as a result. If you look at the thread you will get an idea of what is new. Probably all that you would need is a piston and cap that would be easy to make......

[tagerton]

Great build! It looks like you just rounded the edges of the fins a little bit. How did that go?

My kit should be in the mail. I'm planning on going for max altitude/speed and I'm wondering if I could use a standard Bridgeport mill or CNC mill (both of which I have access to) with some carbide bits to cut a nice bevel on the G10. I believe, due to the supersonic nature of the high altitude flights, a bevel is the best option (over an airfoil). I'm a bit concerned that the ideal bevel either would remove too much material and make the fins too weak, or would not fit the curved shape of the fins very well.

[SinfulDarkLord]

Thank you very much. No I did not round the edges of the fins. All I did was wet sanded the edges. Also some advice it would not be a good idea to bevel them. Since the fins are curved drag wont affect them as much. The main thing you should worry about is getting them glued nicely into the body tube. I understand how you feel about the nature of supersonic flights but in this case it will not matter since it will happen so fast that supersonic speeds wont have any time to do any damage to the model. Good luck on your build.

[cwbullet]

If you do fin to fin fiberglass, you can bevel them with the process.

[tagerton]

If you do fin to fin fiberglass, you can bevel them with the process.

So you are saying when when I cut the glass for the fins to make the sheet slightly smaller than the fins to make a rough beveled edge. Then I would sand it to finish?

I was not planning on doing any fiberglassing on this rocket. I think it will be lower weight, drag, and work if I don't. I was planning on just putting these fins in a mill with a 15 degree offset and just shave off the leading and trailing edges. I think it may work. The fins look to be a bit more curved than expected, which is my main concern. It may require a bit more skill to get the mill to curve around that edge.

[SinfulDarkLord]

tagerton, In my opinion I would best leave them alone. Its up to you however. Good luck on the build.

[tagerton]

tagerton, In my opinion I would best leave them alone. Its up to you however. Good luck on the build.

Just curious what your reasoning behind that is. Would it be too difficult with such thin fins? Or do you think it won't have a significant affect?

[SinfulDarkLord]

tagerton, It would be a lot of work and you only have once chance to do it. If you have experience in glassing then go for it. As for the beveling, I too planned on beveling the fins but it will be difficult. Also its the same thing, you only get once chance. So I decided not to because if I were to mess up I dont know if I can get another fin. So it is best to leave the beveling part out. The glassing is something you can go for. All you should be concerned in is making good fillets with a strong type of epoxy such as Aeropoxy. Like I said its your desicion. If youd like I can look into a way to bevel them without messing it all up. Once again good luck on your build.

[tagerton]

This is just a crazy idea, but what if you used a knife sharpener to put a bevel on. Then you could dull the edge a bit with some sandpaper to you know, not be a knife. I think it would put a very nice, consistent bevel on the fin. You might be able to use an electric knife sharpener too (but I don't have one that I would want to get fiber glass in) Thoughts?

[cwbullet]

That is an interesting why to do it. I never thought of using a knife sharpener.

[freddiejojo]

Tagerton, I too am intrigued by your knife sharpener suggestion. Please advise. In addition, all tests here with the Mariah 38 flying J570 and J510 motors, the kit did NOT have any reinforcement on the fins of any kind and no fins have ever been lost. Just make sure you make fillets per the included instructions. I guess I included the glass cloth for use if you wish it.

Also, I have a report of a Mariah 38 flyer getting 14+K with a J570 as reported by a Raven. I feel pretty good about that.

Kent/GLR

[cwbullet]

I too built mine without a bevel or the fiberglass cloth. I flew to 8000 feel and a warp 9 type motor. No issues.

[tagerton]

I will definitely be trying out a knife sharpener on some spare G10. Unfortunately it will be about a week before I am able to. If anyone has a knife sharpener and a bit of fiberglass, it would be great if they could post some results. I think this may be a really good way to bevel fins.
I may have to 'borrow' my parents electric knife sharpener that has sat unused in the closet for the last 20 years.

[BearMan]

Just wanted to let everyone know I posted some updates in my thread...... Should be helpful to the Mariah 38 as well....


http://www.rocketryforum.com/showthr...005#post356005

[SinfulDarkLord]

I will be taking the Mariah 38 on its first flight on a CTI G79 Smoky Sam. I will post pictures and a video.

[SinfulDarkLord]

Here it is Folks Enjoy. I will edit this post later with the information of how fast and how high it went. Sorry about the bad noise there was some breezy conditions. Sorry no pictures.

[BearMan]

So...... How was it? Did it fly well? Did everything work right? Updates?

[SinfulDarkLord]

So...... How was it? Did it fly well? Did everything work right? Updates?

BearMan, the flight was perfect, there was no issues everything went as planned. Deployment was also perfect no problems there. I used dual deployment since I like dual deployment. Highest altitude reached was 1,681 feet. If your wondering why so low it is because of the wind that was going on caused the Mariah 38 to tilt at an angle and not straight up. The speed was 201 miles per hour. In my opinion thats a nice maximum velocity. One last thing I posted the video on here. If it is not showing up on your end please let me know so that I may try to fix it later.

[SinfulDarkLord]

For all rocksim users. I have read here and there complaints of people not getting accurate Altitude predictions of their Mariah 38 simulations. So I decided to share what you can do to make everything work properly. First off make sure you have already found your CG and Mass of the rocket. So here is where it gets tricky, but with a few pictures I am sure you will know what to do. First off you will be messing with the Cd override tab on rocksim otherwise known as the Coefficient of Drag. Be sure to uncheck the box that says "Calculate Cd at simulation time". For your G and H motors you will be using a Cd of .75 on the sustainer only. For your I and J motors due to their incredible power the Cd changes. You will type in for the sustainer only a Cd of .34 . Be sure all other inputs are zero. After running your simulations one by one you should get good results. By the way my results are all Cesaroni Motors. I hope this helps.

1. G and H motors use 0.75 of Coefficient of Drag

2. I and J motors use 0.34 of Coefficient of Drag

3. How the results should look like more or less. Depending on the weight and CG of your Mariah 38