Astron Sprint XL

I figured out a simplified "Merrick Mount" for the Astron Sprint. I looked for small eyebolts that would work but no luck, so I set to simplify the design and still get the shock absorber action.

I found a ply bulkhead that would fit inside the nose cone and sit against the molded lip of the shoulder, then using a long cotter pin and a small 1 inch fender washer slipped the pin through the the washer and center hole in the bulkhead, the spring assortment I found at Home Depot had a long tapered spring that fit perfect, I put the wide end of the spring against the bulkhead then added a small #6 washer, giving just a slight push I bent the ends of the pin over to hold everything together. Trimmed off the ends with heavy cutters and it's ready to install.

It works better than I would have thought. I got curious as to weight and found out that the included clay is .45 oz, this "Merrick Mount" is also .45 oz.

Now to simply epoxy the mount into the nose cone and tie a kevlar cord to the cotter pin eyelet.

I am going to add this mount to more of my kits, it is just one of those head slapper ideas that is simple and just plain works.

Pics later, gotta head off to work.

See ya,
Rod

Here,s mine..! I threw in a coupla pics of my cheapazz display stand for the heck of it! I sure hope the weather will be good Saturday!!I wanna see this go UP!!

little late perhaps, maybe in time for the next bird...I have made small u-bolts from 2-56 all thread push/pull rods from the rc aircraft section of the hobby shop.
rex

Here are the pics for the solution I came up with for this "Merrick mount" Very simple and will work great.
The pics are of the mount parts, couple steps to assemble, and compare mount to clay weight.

Will wait until I am ready to finish and have the weight right for a AT single use CG, then epoxy mount into nose cone.

gdjsky01 said:

Would this be good for Ellis E12-10s? I have a few.

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One of 2 things will happen if you do.... Awesome high altitude flight, or CATO and kindling......

kelltym88 said:

One of 2 things will happen if you do.... Awesome high altitude flight, or CATO and kindling......

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Sounds like a plan! :wink:
I popped over to Jonrocket and ordered one... I have 3 E12-10s... will it survive?? We'll see...

RodRocket said:

Here are the pics for the solution I came up with for this "Merrick mount" Very simple and will work great.
The pics are of the mount parts, couple steps to assemble, and compare mount to clay weight.

Will wait until I am ready to finish and have the weight right for a AT single use CG, then epoxy mount into nose cone.

Click to expand...

First off, I'm really pleased to see that you fit a Merrick Mount onto your bird, awesome! Also, thank you so much for keeping with the name "Merrick Mount", I appreciate that, and so does my son. I like your modification, and hopefully that's a stainless steel cotter pin and not an aluminum one?? I hope there's not enough force to make the washer slip over the bent tips of the pin. That was my only concern. However, you probably save a little on the weight by using the pin, so good on ya! Nice job!!!

It was your idea not mine sir. I just adapted it to work with my smaller models. Pin is steel and the spring is pretty soft but strong enough to hold. Kevlar cord should be fine with the mount. It's long enough that the shock might not be as severe as I think.

Painting the Sprint XL over the next few days. Think I will go with red nose and fins.

See ya,
Rod

I bought this model on compulsion from an online vendor where I did not notice the fairing on the boat tail to accomadate the motor retainer. I rarely build with the retainer and now need to figure a way to remove this feature... cut it off and fill with a little expanding foam & thin glass. I have always admired this design, its curves and simple paint scheme. Kickin' it oldschool.

Anyone have a decent ROCKSIM or Ork file for this bird?

RodRocket said:

It was your idea not mine sir. I just adapted it to work with my smaller models. Pin is steel and the spring is pretty soft but strong enough to hold. Kevlar cord should be fine with the mount. It's long enough that the shock might not be as severe as I think.

Painting the Sprint XL over the next few days. Think I will go with red nose and fins.

See ya,
Rod

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This is what mine ended up looking like with red and black.

Looks very 'bomb like'. :eyeroll:

Nice job!

Fun build nice flyer also.

Dang... I wish I would have thought of checking it in openroc first. I suppose I could get most of the clay back out.
I was surprised at how heavy the nose is with the clay.

Dont worry... i will do some static testing first.
Attached my openrocket upscale, it looks to
be one caliber with an E-9.

View attachment estes_sprint XL.ork

I never built a Sprint, but this XL version has me VERY tempted. I look ahead to your build.

Robot Vacuum

She's a Beaut! Nice work!

Alanbrad said:

I never built a Sprint, but this XL version has me VERY tempted. I look ahead to your build.

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Should continue his weekend.

Here is a link to mine on my website. Recently flown for the first time on an Estes C11-5. Nice flight! https://www.angelfire.com/space/r_watkins/EstesAstronSprintXL.html

Rocketron

Flew mine on a D9-7 yesterday and it was a nice flight next time I will put a E9 in it. I have had some E12 blow so I am not using them no more.

On goes the fin can after completion of the fin filleting.

Great progress, Jeff!

And it flies:


On a C11-7 to 710'.
Delay a bit long but that could have been the rod angle. Had it been almost vertical, it may have been just right.

gdjsky01 said:

And it flies:


On a C11-7 to 710'.
Delay a bit long but that could have been the rod angle. Had it been almost vertical, it may have been just right.

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The XL prototype on a F35-11.. on its way to over 2,600'.. ROCKET AND ROLL!