JCINTEXAS

As you have probably heard, the world speed record for RC jets was officially set on January 26, 2010 in the Dominican Republic. The new world record of 337 MPH was set by David Shulman and Axel Hache flying a JMP Firebird. Here is another way of looking at this speed record.
"SCALE SPEED"
Firebird flew an average of 337.18 MPH......but what was the Firebird's "scale speed"? Scale speed is figured as 'fuselage lengths per second'.
The Firebird's scale speed was approximately 2,788 MPH That is Mach 3.6

Here's the math:
Firebird length = 92.5 inches
5,280 feet per mile
X 1263,360 inches in a mile
X 237.18 mph
21,363,724 inches per hour Divided by 92.5 = 230,959 (fuselage lengths per hour)
230,959 (fuselage lengths per hour) divided by 60 = 3,849.3 (fuselage lengths per minute)
3,849.3 (fuselage lengths per minute) divided by 60 = 64.15 (fuselage lengths per second)

F-15 Eagle length = 63ft 9in = 765 inches X 64.15 (fuselage lengths per second) = 49074.75 inches per second X 60 = 2,944,485 inches per minute X 60 minutes per hour = 176,669,100 inches per hour.
176,669,100 inches per hour divided by 63,360 inches in a mile = 2,788 MPH

Explanation:
At 337.18 MPH the Firebird is flying at 64.15 fuselage lengths per second
IF the Firebird were the same size as the USAF F-15 Eagle, the fuselage length would be 63ft 9in = 765 inches
IF the F-15 Eagle flew 64.15 fuselage lengths per second that would be 2,788 MPH = Mach 3.6 (at sea level 70 degrees F)

Here's a crosscheck on the calculations:
The F-15 Eagle is 8.27 times the fuselage length of the RC Firebird
337.18 MPH X 8.27 = 2,788.5 MPH

Best Regards
FASSTFLIER

PS: See the video of the speed record flight on YouTube http://www.youtube.com/watch?v=7cOIg-YIj7Q

AndyAndrews

It must have had ants for pilots.

BeanerECMO

Aren't the drones at NAWC China Lake, Edwards AFB etc. RC? They might be the fastest. Congrats on a great achievement.

realdeal

That is one fast airplane. I'd love to see more video.

Did you guys have any data logging that recorded peak speed? I bet you had a good 20-30 mph higher peak at some point.

Keith

hvnmodels

SHUI IS THE FATSEST!!!!! HE HAS THE PAPERWORK TO PROVE IT!!!!

Shaun Evans

Yeah,

Shui may be the fastest, but I'm still the FATTEST!!!

Greg G

What would that record be expressed in terms of fuselage lengths?

buz914

I'm not trying to start any trouble, but I always thought speed could not be scaled up or down because speed has to do with time. And time can not be altered "scaled up" ?
I've always wondered if this was correct? Please explain.

Buz

AFTERBURNER1

Yes,,,,, Please splain to my 2 post amigo...

JCINTEXAS

_________________________________________________
Buz,
According to Einstein, velocity does alter time...but E=MC(squared) is way beyond our discussion here. (I know a little about bass fishin but hardly anything about nuclear fishin ) If we look at speed in terms of fuselage lengths traveled per second we can get some interesting comparisons. Have you ever seen a big Lockheed C-5 Galaxy or a Boeing C-17 Globemaster on final for landing? It looks like it's hardly moving and about to fall out of the sky. The plane is flying at 130 plus knots, but it looks very slow because of the aircraft's size. Another example is when you see a big ship underway at 20 knots and running beside it at the same speed is a 15 ft boat with an outboard motor. The little outboard looks like it's really hauling while the big ship is just crawling. So we are talking about perceptions...perceived speed. Anyway, what I was saying in my original post...in terms of fuselage lengths traveled per second, if the RC jet were scaled up to the size of an F-15 Eagle, and flew at the same rate as the model jet, 64.15 fuselage lengths per second... then it would be flying at 2,788.5 MPH ... about Mach 3.6
Regards
JC (FASSTFLIER)

PS: I think this is why we hear about cars being hit by trains at RR crossings. The drivers think they can "beat the train" because the train does not appear to be moving very fast.

olnico

Hi JC.

Your computation is perfectly correct in terms of visual perception of the speed. And I believe that this is what your term "scale speed" refers to.
On that respect it is a very interesting computation to do for scale competitors. With that stuff people could adjust their flying speed so that they look perfectly scale in flight.

Thank you for sharing your thoughts.

AndyAndrews

Thats a great point. This is why it doesn't look scale to fly your Skymaster F4 with a P200 full throttle. lol.

JCINTEXAS

Thank you Oli,
I appreciate your comment.
Happy flying in Dubai.
Regards
JC (FASSTFLIER)

causeitflies

It's much simpler to take the scale of the plane and multiply by the speed.
Example: A 1/6 scale plane flying at 100mph is flying at a scale speed of 600mph, a 1/7 plane at 700mph, a 1/8 at 800mph etc...

JCINTEXAS

__________________________________________________ ____________________

Hi Mark,
You're right.
However....I don't think the JMP Firebird is a scale model of a "full-size" plane.
So I compared it to the F-15 Eagle for purposes of illustration.
We are talking about an observer's "perceived speed" of airplanes.
If a "full-scale" F-15 flies over your head at 340 MPH at an altitude of 20 fuselage lengths (1,280 feet) above the ground where you are standing...the "apparent speed" won't be very impressive. If a RC model jet flies over you at 340 MPH at an altitude of 20 fuselage lengths (154 feet) above the ground where you are standing...the "apparent speed" will be very impressive. It would look like what the F-15 would look like if it was doing 2,788 MPH (minus the sonic boom).
Regards
JC (FASSTFLIER)

causeitflies

For a sport plane you can use the size/scale of the pilot as the scale reference
I doubt the Firebird would be as large as an F-15 if scaled up going by the size of the pilot. More like 1/6 (guess) rather than 1/8.27. So speed would look more like 2023.08mph

mungrelv8ute

Congratulations to Dave and Axel, an incredible achievement 337MPH…!

However that makes this record even more incredible, given that they don’t have a motor…just mother nature 392MPH

http://www.youtube.com/watch?v=WaQB1...eature=related