Mega Rebel with Monokote

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Sorry for being vague, trying to work quickly on my phone.

I was just musing about how the CP of the open-framed rocket is a bit of a mystery (to me at least), which makes me wonder whether the skinned rocket will be more or less stable.

It might be totally fine, I just realized that the answer isn’t necessarily obvious (again, to me). However, the skinned rocket would be easy to model in OR or Rocksim to find CP if desired. The unskinned rocket... who knows.

I confess, that I tend to build kits, not design new rockets. So I do not spend much time on Center of Pressure vs Center of Gravity relationships. However, I do normally conduct the old 'string test' (attaching a string to the rocket at the CG, w/ motor installed, and swinging it around).

When initially building the Mega Rebel, I was surprised that no CG was listed. When I contacted the Rockitarium (kit seller/designer), they stated that the Mega Rebel had been an act of trial and error. This was why I was careful to add CG info (that I obtained) during my Mega Rebel build.

So, living in the middle of nowhere in northeast Arkansas can have its advantages.
 
So, living in the middle of nowhere in northeast Arkansas can have its advantages.
If a tree launches a rocket in the woods and the rocket does a St.Louis Arch and then a long landshark, but nobody else sees it, it didn’t really happen!
 
It looks like the kit's vertical 'spars' stick out a little bit beyond the outer diameter edge of the horizontal rings (maybe 1/16" +/-) and this makes it hard to cover the openings with a 'smooth' panel surface?

Sorry I am replying so late to your comment, Space Ranger. Yes, you are correct. I had considered sanding the vertical 'spars', but decided it wasn't worth the effort. In hind sight, it might have been worth the effort.
 
MONOKOTE TECHNICAL ALERT! :headspinning:

The Mega Rebel is made of PLYWOOD, not balsa. Monokote does not attach to plywood as well as balsa, so I had to increase the temperature.

I initially stated that I was doing an initial 'attach' of 250 F. This turned out to be more like 275 F, or higher. When attaching monokote over monokote, it was closer to 300 F.

Still did final stick/shrink at 325 F. When using heat gun, used 'HIGH' setting.
 
If a tree launches a rocket in the woods and the rocket does a St.Louis Arch and then a long landshark, but nobody else sees it, it didn’t really happen!

Exactly. :dancingelephant:

I tend to go to Memphis launches (1-1/2 hour drive). Once the Covid stuff calms down, I hope to get up to some St. Louis launches (3-1/2 hour drive).
 
I tend to think that the standard rocket simulation computer codes do not have any real meaning for the flow pattern around the Mega Rebel. So, if they did give a CP location how much would valid would it be. The original Mega Rebel flies, therefore it must be alright. The original question is how does the CP location change. We don't have calculations showing how it changes, but I tend to think it will be OK. The proof is in the flying or Daddy might say use "mindsim".
 
Onward to covering the fins. I debated doing this, since I am adding weight aft of the CG. But plastic covering is pretty light, and it looks good.

Decided to use red.

m_IMG_1261small.jpg
 
And a look on the back side. A lot of better monokote guys would stretch it over. Just doing what works for me.

m_IMG_1265small.jpg
 
Every once in a while, there is a color that the bugs like. Had a Fokker Dr.1 triplane with a yellow top wing and elevator; some little gnat just loved it, there would be 10+ when it sat for a little while at the RC airfield.

A little jumping spider seems to like the orange monokote. It patiently sat while I covered two more fins. I did release outside, on a bush.

m_IMG_1271small.jpg
 
Gosh, has it been 2 years? Shortly after I got to this point, I got extremely busy at work. Then some health issues. Then busy at work again.

But I finally got the Mega Rebel w/ Monokote out again!

IMG_6374.JPG
 
In the previous views, the camera is looking north. There is a very slight breeze out of the northeast.

For about 30 feet, the Mega Rebel went straight up. Then, it made a turn from north to southeast. But still going up at a fairly good angle.

IMG_6392.JPG
 
And then things got STRANGE. (Sorry, that is all the pics.) :shocked:

So, I am looking into the sun, trying to see the rocket. I don't hear the rocket motor.

Then, I see an object moving from east to west! It is my Mega Rebel, in coast mode. But it almost flying along, no motor.

Then the ejection charge popped........... but the parachute did not open. :facepalm:
 
I saw where the Mega Rebel landed: in the middle of a bean field. I searched, but could not find it.

Dang. :angiefavorite:

It did fly. But I am not sure about calling it successful. I really like the way it looked.

But I am wondering if variations in my Monokote covering led to instability at "rocket speeds". I think I will build another Mega Rebel, but I am not sure I would go Monokote again.
 
I saw where the Mega Rebel landed: in the middle of a bean field. I searched, but could not find it.

Dang. :angiefavorite:

It did fly. But I am not sure about calling it successful. I really like the way it looked.

But I am wondering if variations in my Monokote covering led to instability at "rocket speeds". I think I will build another Mega Rebel, but I am not sure I would go Monokote again.
What a shame! Nifty looking rocket, interesting experiment in materials and lost to the evil weed that is the soybean!
 
I saw where the Mega Rebel landed: in the middle of a bean field. I searched, but could not find it.
$&%^ing soybeans. 🤬
I think I will build another Mega Rebel, but I am not sure I would go Monokote again.
It was a great experiment, but I definitely understand if you do not want to go that route again. Looked like a *lot* of work.
 
Back
Top