icing

This video was EXTREMELY interesting! Thanks for pointing it out,
Bumper.

Off topic a bit, what is the model aircraft in the background with two
turboprops and two jet engines? It says NASA 600, but I couldn't find
any info using Google. Is it just a model, or is there a real one
flying around?

-John

bumper wrote:
This video was mentioned on backcountrypilot.org. I figured I understood
tailplane icing, etc. But watching the video was an eye-opener. This also
very much applies to pilots who don't plan on flying in icing conditions. A
failed gap seal on a glider comes to mind as well.

At first I was going to skip this video as it's 23 minutes long. Please
watch it, there's not a boring moment. bumper

http://video.google.com/videoplay?do...23060735779946

I haven't watched the Google Video, but if it's the NASA video on
Icing (with discussion of SLD - Supercooled Large Droplets), I bet
it's a DeHavelland Twin Otter that NASA Lewis/Glenn used for one of
their many Icing Campaigns. I'm grateful for the work (and risk)
those guys have taken on. Changing flaps may be the key to staying in
control...

I've been involved in a few Icing Conferences (for work) and studied
Roselawn. The tools to predict the effects of icing on airfoils (and
airplanes) are getting better. There is still much left to be
done...and actual flight testing in icing (research or certification
of new airplanes) is dicey business -- especially since they de-
commissioned the USAF ice tanker (a KC-135 that sprayed water instead
of fuel).

The turboprop airplanes and commuter jets tend to not have
hydraulically driven controls (vice the big jets) and use boots
instead of hot air -- manual or tab-driven controls and boots are less
capable against ice accumulation. Even on the big jets, the hot air
systems are considered "anti-ice" as opposed to "de-ice" equipment:
they help PREVENT ice buildup (when used properly, or in icing
conditions that don't exceed the system capability). To "de-ice" a
big ice buildup takes much more capable equipment, which translates
into weight, power, complexity and so forth. Bottom line: have a
very healthy respect for icing (and hope your airline pilot does).

Good observation of the similarity with gap seals. For big jets, we
sometimes test missing parts (MEL or CDL certification), such as seals
-- to verify the airplane still has satisfactory handling
characteristics with seals missing (e.g. on one side of wing or
tail). It might be wise to find out how well our gliders work with
one or more gap seals missing or venting. A diminished L/D is one
thing. Loss of control is cause for alarm. As usual, don't try this
at home...

-Pete
#309

On Feb 15, 6:53*am, bumper wrote:
Off topic a bit, what is the model aircraft in the background with two
turboprops and two jet engines? It says NASA 600, but I couldn't find
any info using Google. Is it just a model, or is there a real one
flying around?

-John

The model in the background looks like a Gulfstream. Probably a
Gulfstream II ? The horizontal elliptical windows sure look like the
Gulfstream trademark to me. I guess they installed the turboprop on
the jet powered aircraft to study effects of tailplane icing on a
turboprop aircraft, but with jet engines as extra safety items (?)
Maybe the jets would provide not only extra thrust but also some "de-
icing" power???

Ray Lovinggood
Carrboro, North Carolina, USA

On Feb 15, 12:50*pm, rlovinggood wrote:
The model in the background looks like a Gulfstream. *Probably a
Gulfstream II ? *The horizontal elliptical windows sure look like the
Gulfstream trademark to me. *I guess they installed the turboprop on
the jet powered aircraft to study effects of tailplane icing on a
turboprop aircraft, but with jet engines as extra safety items (?)
Maybe the jets would provide not only extra thrust but also some "de-
icing" power???

Ray Lovinggood
Carrboro, North Carolina, USA

After actually watching the entire, sobering, video, let me change my
answer: I still think the model is a Gulfstream II, but it had
NOTHING to do with the icing experiment. By the looks of the prop on
the turboprop engine, I say the model was a testbed for the propeller.

Ray