G10/12 at Mach 2?

Here's a link to an ablative paint vendor. Their products are used on military
rockets and missiles. As the paint ablates, heat is carried off.

https://flamemaster.com/coatings/

blackjack2564 said:

Yes....look at the NC picture above. It's standard fiberglass NC from Ken Allen [Performance Hobbies}...just replaced the metal tip with custom phenolic. Then coated whole thing with epoxy. Sanded smooth on lath.

NC shoulder/coupler 2x's wall...... standard glass.

Just the Vent band carbon on cone.
All of fincan/airframe carbon.

Contact Charlie through his website, leave phone # and brief description of what interested in...he will call back to discuss.

Click to expand...

Am wondering if tip replacement was necessary for Rf purposes as usually there is a null off the tip of a vertical antenna and the majority of the
propagation is out the sides of the nosecone? If the heat characteristics for the phenolic is better than aluminum for high speed flight I could see
that reasoning but is there some other logic I'm not realizing that necessitated replacing the Al tip? Kurt

Metal conducts the heat about, phenolic less so. I don't think anyone's worried about RF stuff ( although I wouldn't be surprised to hear about an antenna burrowed into phenolic ).

ksaves2 said:

Am wondering if tip replacement was necessary for Rf purposes as usually there is a null off the tip of a vertical antenna and the majority of the
propagation is out the sides of the nosecone? If the heat characteristics for the phenolic is better than aluminum for high speed flight I could see
that reasoning but is there some other logic I'm not realizing that necessitated replacing the Al tip? Kurt

Click to expand...

Kurt, Very valid point regarding your RF observation. I've been pondering the same about whether or not the replacement of the alum. tip was necessary. Metal does conduct heat better or we wouldn't be using it to fry eggs in, but the question remains, is it necessary for 10 seconds of flight at M2+? I will likely fly with the alum tip in place....

I had heard the whole fin can is reinforced by a motor case in a MD configuration, both CJ and TFish have shared their hard won knowledge with us and continue to do so - thanks !! :wave:

Warner , CErving and I have 54 MDs to build .. we will try the suggested techniques but will probably get bested by Cris building a Mongoose 54 stock & getting it back.

Kenny

Regarding the phenolic tip:

This rocket is a proof of concept for a much larger one.
Gps has a 6in antenna.... to make space in NC work, we needed the antenna to extend through center of tip, within 1/4inch of the tip's tip. The phenolic tip is 2.5 long, so 2 1/4 has antenna inside.
Loss of 5 inches in front of cone was replaced by 5in in front of coupler.

Heat encountered on the larger project may entail higher M levels [as much as m-3.5 for 30 sec....P to a long burn N] Ablative tip more desirable than metal & heat transfer. In this case the entire cone may require ablative coating.

If this is the case....the tip and shoulder will provide an edge/lip. Cone may actually be a few thousandths smaller dial. Ablative will "fill" the entire cone between and turned to spec on lathe.

You must remember this and many other projects are just test mules for our full scale spin stabilized sounding rocket. Sparrow Hv-Arcus.

This NC and rocket could very well end up on top of a 4in. minimum booster & really get hammered.

So yes, it [phenolic] is not required at all, for a 3in rocket with any motor in it.
BUT in this case, with an antenna through the center & being a test mule, it is needed.

We have no intention of flying 3GPS.....3 altimeters and Rf tracker in final, just testing all & how they interact with each other.

Great! That makes it exceedingly clear and makes sense to me now. How many trackers in the final iteration? One GPS and one RDF backup?

Kurt

I think i heard somewhere that cutting slots in MD rockets for fins to go into will weaken the body tube alot.

Click to expand...

I built my 54mm Tomach with slotted airframe. No problems to Mach 1.8. Build thread (including my rationale on the build I think) here: https://forum.ausrocketry.com/viewtopic.php?f=6&t=4758
No problems with any paint or fillets cracking.

I have also done the half-scale Apache using a similar method. If I can get to a launch that isn't cancelled due to weather I might even get to fly it. Build thread here: https://forum.ausrocketry.com/viewtopic.php?f=6&t=5019&start=30

One thing I should mention is that my airframes (tail end anyway) do not take any thrust. I use the front of the motor casing to couple to an Aeropack minimum diameter style motor mount. "Thrust ring" does not contact the airframe. Tailcan stays in tension. This is not an insignificant difference in having to rely on the integrity of the tube.

blackjack2564 said:

Regarding the phenolic tip:


Gps has a 6in antenna.... to make space in NC work, we needed the antenna to extend through center of tip, within 1/4inch of the tip's tip. The phenolic tip is 2.5 long, so 2 1/4 has antenna inside.

Click to expand...

Yes,.. if you're going to put an ant up into it, it definitely can not be metal.

OverTheTop said:

I built my 54mm Tomach with slotted airframe. No problems to Mach 1.8. Build thread (including my rationale on the build I think) here: https://forum.ausrocketry.com/viewtopic.php?f=6&t=4758
No problems with any paint or fillets cracking.

I have also done the half-scale Apache using a similar method. If I can get to a launch that isn't cancelled due to weather I might even get to fly it. Build thread here: https://forum.ausrocketry.com/viewtopic.php?f=6&t=5019&start=30

One thing I should mention is that my airframes (tail end anyway) do not take any thrust. I use the front of the motor casing to couple to an Aeropack minimum diameter style motor mount. "Thrust ring" does not contact the airframe. Tailcan stays in tension. This is not an insignificant difference in having to rely on the integrity of the tube.

Click to expand...

Thanks for posting your build threads..... I haven't had to the time to study your threads, but at a glance it appears you have proof that this concept works (slotting of a MD build). Excellent!