[AR] Re: AR Nose Heating (was:. 3D-printed RL-10)

From: Team Icarus SDSU <rocketteamicarus@xxxxxxxxx>
To: arocket@xxxxxxxxxxxxx
Date: Wed, 5 Apr 2017 19:01:42 -0700

Chuck and Ken:

Thanks for the insight.

How long did Qu8k spend in the high supersonic realm? What about you, Ken?
My concern is that this rocket is expected to stay above Mach 3 from
10,000-100,000'. This seems to be a longer heating pulse than the average
high power rocket.

That said, the nice thing about the dart design is significant thermal mass
to absorb the heating pulse, as higher density is a desirable feature.
Steel would absolutely be cheaper to purchase and simplify manufafuring.

I am a bit confused by the comment on shock reattatchment. I have read this
several places on high power rocketry forums but I ran some schlieren
photography sessions last semester on models with ogive noses and
cylindrical center sections. We did not observe this phenomena.

On Apr 5, 2017 5:15 PM, "Redacted sender crogers168 for DMARC" <
dmarc-noreply@xxxxxxxxxxxxx> wrote:

You can calculate the radiation equilibrium temperature on the nose cone,
and get a very high surface temperature.  But this is analogous to the skin
temperature of an SR-71 in cruise.

Analogy for a sounding rocket type heat exposure like this, is a 750 deg F
to 1,000 deg F oven, you stick the rocket in for 20 seconds and then pull
it out.  Much lower temperature.  Unfortunately much more detailed analysis
to get the time dependent thermal effects on the surface temperature.

As Ken mentioned, many high power rockets have flown to Mach 3, and a
little over, with metal nose tips and composite nose cones.

Example below is the Derek Deville Qu8k Q motor rocket, which used a
fiberglass nose cone with aluminum end plates, and a stainless steel nose
tip.  Replacing the fiberglass with aluminum could probably easily stretch
this configuration to Mach 4.

[image: Qu8k.jpg]
http://ddeville.com/derek/Qu8k.html

Main advantage of Inconel versus a high temperature steel is weight.  Note
from the Qu8k rocket that the steel nose tip is only part of the nose cone,
weight savings from Inconel will be minimal.  And the extra weight from
using high temperature steel is literally at the best point on the rocket,
the nose tip, moving the CG forward.

Chuck Rogers

-----Original Message-----
From: KEN BIBA <kenbiba@xxxxxx>
To: arocket <arocket@xxxxxxxxxxxxx>
Sent: Wed, Apr 5, 2017 4:43 pm
Subject: [AR] Re: AR Nose Heating (was:. 3D-printed RL-10)

Our experience in flying to the 100k’+ region with peak speeds in the Mach
2.5-3.5 domain suggests heating highly overrated.   We are flying largely
composite airframes with modest grade epoxy with composite (fiberglass)
nosecones with an aluminum tip - VK shape.

We have seen no signs of nosecone heating … and the only heat effects on
the airframe we have seen has been on heavy paint on the sustainer body
about 3’ back from the nosecone tip .. where it appears the shockwave
returns to the body.   It got a bit smeared.   Hope to actually, finally
fly an instrumented nosecone this summer to measure nosecone heating.

K

On Apr 5, 2017, at 4:33 PM, Team Icarus SDSU <rocketteamicarus@xxxxxxxxx>
wrote:

This question is also of interest to our projects.

It's a couple years from launch, but Icarus 3 is likely to remain in the
M=3.0-4.0 range for the first 100,000' of its flight; significant heating
is expected. We need to perform more in-depth analysis, but the current
plan is to build the dart section from lathe-turned inconel.

Alex Lewis

On Tue, Apr 4, 2017 at 6:22 PM, William Claybaugh <wclaybaugh2@xxxxxxxxx>
wrote:

Do (AR) nose tips see the kind of heating that would require inconel or
the like?

I've wondered if USC/RPL's titanium nose tips are justified for a Mach 5
mission w/ a very short heat pulse....

To be clear, I have not done my own analysis, I'm asking two questions.

Bill

On Tue, Apr 4, 2017 at 7:01 PM Ben Brockert <wikkit@xxxxxxxxx> wrote:

I visited Atlantic Precision a couple years ago, one of the few shops in
the US with multiple EOS DMLS machines, and they were actively printing
parts for the RL-10 even back then. Printing the chamber is big and flashy,
but there's a lot of utility in cranking out highly detailed inco or haynes
parts.

For any part with moderate complexity of the nickel alloys it's now
cheaper to print and lightly post-machine than to machine from solid
material, even at small production quantities.

That is of relevance to AR because a one-off printed and sanded nickel
alloy nose tip for a higher performance hobby rocket should quite
affordable, especially if you shop around and make it clear that you're not
in a rush for the part.

On Tuesday, April 4, 2017, Dave Klingler <davek@xxxxxxxxxxxxxxxx> wrote:

Ehhhh…one can always ask.  Sometimes people like to talk about where
they’re headed. :)

Dave

On Apr 4, 2017, at 1:17 PM, William Claybaugh <wclaybaugh2@xxxxxxxxx>
wrote:

Dave:

Anyone privy to such information is likely subject to a non-disclosure
agreement....

Bill

On Tue, Apr 4, 2017 at 12:24 PM Dave Klingler <davek@xxxxxxxxxxxxxxxx>
wrote:

I just saw an article over at parabolicarc about AJR's first 3d-printed
thrust chamber firing.  I’m trying to decide whether, from what I’ve read,
they’re substituting copper for stainless in a few spots.

I think design changes are probably unlikely this early, but at the very
least the new manufacturing process opens up the way for different
materials and more elaborate cooling passages that wouldn’t be possible
using the old tube benders.  Is anyone on this list privy to what sort of
plans AJR has for higher chamber pressures or other improvements to the
RL-10?  What’s the schedule for doing complete engine certification?

Dave Klingler

References:
- [AR] Re: AR Nose Heating (was:. 3D-printed RL-10)
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[AR] Re: AR Nose Heating (was:. 3D-printed RL-10)

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