Immelman : How many G's?

[Ollie]

How many G's do you need to pull to complete an Immelman?

The Italians supposedly did one at the Malta airshow (or so they say on Airliners.net) : http://www.airliners.net/discussions/av ... ain/203879

I say it's bulldroppings, unless they trespassed the limits. Bombardier lists the 415's structure at +3.25/-1.0.

And after that they cry when a 415 loses a tail or something...

[Jack Cook]

An interesting set of photos for sure.
But why stress an aircraft unnecessarly especially the one you risk your life in? Isn't firebombing dangerous enough?
Actually the verbal attack session there was just has entertaining. I wonder if HVD IV lurks there under an assumed identy?
I regards to G's who knows? I sure don't know but ask yourself, how many did ol Max put on his Enidecker?

[airnutz]

When I read your question Ollie, I thought immediately of "Fish" Salmon's
1G barrel-roll of the Dash80, as well as Bob Hoovers iced-tea trick. After
reading the airliners forum discussion...I'd really LUV to see the video!!!
The proof'll be in the puddin'...

[Dragonflydh90]

Quite a plausible pic.....as mentioned on the Airliners forum the aircraft began its water drop a lot earlier and at the point the pic is taken is reaching approx 80% of the looping portion with, after dropping 99% of its water load, I imagine plenty of energy and Im sure a surplus of power to help out, from then onward the roll of the top is quite straight forward especially if on a slight down line.
As for 'G' required for a roll of the top, somewhere near 3 at the beginning and quite possible slightly less than 1 crossing the top and for the rolling portion again maybe slightly less than 1 to start finishing with perhaps 3 on the pullout (a bit like a barrel roll).

Not a particularly dangerous maneuver and I imagine within the structural limits of the aircraft, having said that it would have been great to see....rather spectacular. (with the way the pic is cropped Im sure it seems a lot closer than it really is)

I have seen topdressing aircraft, PAC Fletchers and Crescos doing much the same sort of act at shows.

Let the Flaming begin.........................................

[expat]

Looking at the way the water is falling from the aircracft , id say the picture is upsidedown ...not the aircraft.....just my tuppence worth

[Randy Haskin]

I thought immediately of "Fish" Salmon's
1G barrel-roll of the Dash80

Tex Johnston?

[Randy Haskin]

Looking at the way the water is falling from the aircracft , id say the picture is upsidedown ...not the aircraft.....just my tuppence worth

Yep, that was my take on it, too. I wonder how the pilot is performing an Immelmann, yet the elevators are strangely in a neutral position.

BUT...

Look at this series of photos!

[slinky]

Neat set of photos, and yes, it was Tex Johnson that rolled the -80 prototype TWICE over the Seattle Regatta. He about got fired, but the free advertising from the stunt helped seal the future 707/135 airframes fate and the rest is history.... Pretty cool. Tailwinds. Steve.

[airnutz]

I thought immediately of "Fish" Salmon's
1G barrel-roll of the Dash80

Tex Johnston?

How humiliatin'....sigh...the first thing to go is the memory....

[Ollie]

So maybe they did it, but then, I'd never do such a thing with this aircraft, steep turns are wild enough with a water bomber.

Crazy Italians...

[bdk]

Looks like a steep turn to me with the camera pointing almost straight up.

[B25PBYGUY]

Interestingly, I have been only a lurker here, but find myself posting a couple of times here today on a couple of topics. I couldnt let this one go by. I'm type rated in both the CL-215 and CL-415 (depicted here).

Indeed, both airframes are stressed to +3.25G and a -1.0G with flaps extended to 15deg. Otherwise, 3.0G and a -1.0G. Flaps 15 are used for scooping and dropping. Normal drop speed is 110 to 115 kts. 129kts is the water door limiting speed
My instructor in the 215 (Doug Adkins, the original experimental test pilot for both airframes) told me he did once loop a CL-215 with flaps at 15deg.
I dont recall him releasing 6 tons of water concurrently. Thats 6.75 tons in the 415.
Both the 215, and 415, due to their short coupling (read, moment arm) between the area of the velocity of water being released(the surrounding air is accellerated creating a lower static pressure), and the horizontal stab which produces negative lift, does cause a significant pitch up when the load is released. The pilot adds forward stick pressure to minimize this tendency.

Looking at these photos, and the momentum of the water released, leads me to suspect this is not a loop or Immelman. But, it could be done.
I used to execute 3.25g loops (not in a waterbomber) on a regular basis.
The 1/2 roll on top however would be challenging in a 215/415 due to the large wing damping provided for by its planform. The 415 does sport hydraulically boosted flight controls whereas the 215 is cabled.

Its also interesting to recall the Italians have had several fatal crashes with Waterbombers. These are both fine airplanes, and with above ground water available, unbeatable in fire suppression.
I hope this insight is helpful. Now back to flying the B-17....

[Robbie Stuart]

PBY B25 DUDE, That was a very interesting comment about this post. Thats one of the things I love about this board is that we have people out there that have some very interesting experience & knowledge. Tell the folks with the Belle Robbie at EPPS says hello. Keep the dirty side down.
Regards
Robbie

[B25PBYGUY]

OK Robbie! Myself and Mike are flying it this weekend, and next weekend its me and John. Scott and staff will be there too. We'll all arrive at CHS tomorrow and fly the weekend, then repo to INT for media on Mon. Please say hello to Pat.
Yeah, I had to comment on those photos. Also, they do not depict terra firma in the shot, although that could be manipulated these days. I still remain current in the 215 as well.
Regards,
Bob

[Ollie]

Thanks for the comments Bob, it all looks clear to me now.

Probably steep turn with the camera directly underneath it.