Full marks for the baby hippo rescue, but ...
Thread Starter
Full marks for the baby hippo rescue, but ...
I stumbled on an interesting video about the rescue of a baby hippo.
I was very surprised to see it was carried, slung from the right skid of an R-44.
Is this an approved and/or recommended way of slinging a load?
Video here:
https://www.facebook.com/NTDLifeOffi...3665593144910/
I was very surprised to see it was carried, slung from the right skid of an R-44.
Is this an approved and/or recommended way of slinging a load?
Video here:
https://www.facebook.com/NTDLifeOffi...3665593144910/
W&B
Let me just slot it into my W&B calculator:
- I see 1 pilot plus 2 pax. I am pretty sure that I could see that the 4th seat was empty.
- The rear PAC also on RH side (for better load observation), but this would at to the lateral CoG issue.
Can anybody with the presumed weight of the baby rhino (incl "packaging"?
- I see 1 pilot plus 2 pax. I am pretty sure that I could see that the 4th seat was empty.
- The rear PAC also on RH side (for better load observation), but this would at to the lateral CoG issue.
Can anybody with the presumed weight of the baby rhino (incl "packaging"?
Join Date: Jun 2010
Location: Germany
Posts: 99
Likes: 0
Received 0 Likes
on
0 Posts
Please tell us your results
Thracian
Join Date: Jun 2008
Location: England & Scotland
Age: 63
Posts: 1,413
Likes: 0
Received 0 Likes
on
0 Posts
Hippos are 25-50kg at birth, but they grow......
3x 180lb passengers (rear sitting same side as the hippo) plus a 110llb hippo (weight shared between front / rear seats equally for the purpose of calculation; though I suppose that is conservative as the weight will centre just behind the rear seat) and 25 gal (US) fuel, no doors gives you an all-up weight of 2281. Inside MAX all-up weight and both fwd (even with my conservative approach) and lateral CofG (according to a downloaded app called iBal).
Still not approved to lift with the skids. They are easily bent out of shape (don't ask how I know).
3x 180lb passengers (rear sitting same side as the hippo) plus a 110llb hippo (weight shared between front / rear seats equally for the purpose of calculation; though I suppose that is conservative as the weight will centre just behind the rear seat) and 25 gal (US) fuel, no doors gives you an all-up weight of 2281. Inside MAX all-up weight and both fwd (even with my conservative approach) and lateral CofG (according to a downloaded app called iBal).
Still not approved to lift with the skids. They are easily bent out of shape (don't ask how I know).
Last edited by John R81; 21st Mar 2017 at 16:54.
Lateral W&B
I agree that the take-off weight is not the issue. After all, Lamu, Kenya, is at sea level. Here is a more detailed description of the rescue, and a longer video. The R44 is clearly flying, albeit right skid down (see video @ 2min 50 sec).
It just goes to show how flexible the R44 is, both from a longitudinal and lateral CoG point of view! You hardly ever have to worry about anything during normal ops.
Maybe this one is not quite normal though. Lateral envelope is +/- 3 inches. Using the assumptions for fuel, pax and cargo weight (50 kg for the hippo baby) from John R81, the lateral CoG comes out exactly at 3.0 in. Any bigger, like 100 kg as estimated by Thracian, and the lat CoG would be way out (4.6 in). Putting the rear pax on the left side could have helped, but who knows maybe their ops procedures require the loadmaster to keep an eye on the external load
P.S.: Calculations done using Co-Pilot for iOS
It just goes to show how flexible the R44 is, both from a longitudinal and lateral CoG point of view! You hardly ever have to worry about anything during normal ops.
Maybe this one is not quite normal though. Lateral envelope is +/- 3 inches. Using the assumptions for fuel, pax and cargo weight (50 kg for the hippo baby) from John R81, the lateral CoG comes out exactly at 3.0 in. Any bigger, like 100 kg as estimated by Thracian, and the lat CoG would be way out (4.6 in). Putting the rear pax on the left side could have helped, but who knows maybe their ops procedures require the loadmaster to keep an eye on the external load
P.S.: Calculations done using Co-Pilot for iOS
Last edited by Hot and Hi; 21st Mar 2017 at 19:44. Reason: Added Youtube video
It doesn't always work though...
On 17.2.2015 Robinson R44 Raven II helicopter ZS-RNF crashed crashed and burnt out after attempting to lift a presumed 100 kg animal attached to the right skid. The accident report # 9411 is here.
The commercial pilot had over 20,000 HRS flying experience (6,500 HRS on type). A weight & balance calculation for the mishap flight was not done, as it was an ad-hoc decision to take the animal. In this case too, the rear pax was placed, same as the pilot and the animal, on the right-hand side. Luckily nobody go hurt, as the pax got out before the R44 (fitted with bladder tanks, which ruptured during the accident sequence) burst into flames. (The animal was dead before take-off, and was burnt beyond recognition after take-off, so its weight could only be estimated.)
The accident investigator from the South African CAA determined that the lateral CoG for this operation couldn't be calculated, as - according to him or her - "the right skid has an unknown arm datum". Therefore the official accident report didn't calculate the actual lateral CoG for this flight. The report ventures however to find that
I must wonder how John R81 or I were able to do our calculations then 
. Maybe taking the skid position from the airframe dimensions graph in the POH is an entirely unscientific approach?
The commercial pilot had over 20,000 HRS flying experience (6,500 HRS on type). A weight & balance calculation for the mishap flight was not done, as it was an ad-hoc decision to take the animal. In this case too, the rear pax was placed, same as the pilot and the animal, on the right-hand side. Luckily nobody go hurt, as the pax got out before the R44 (fitted with bladder tanks, which ruptured during the accident sequence) burst into flames. (The animal was dead before take-off, and was burnt beyond recognition after take-off, so its weight could only be estimated.)
The accident investigator from the South African CAA determined that the lateral CoG for this operation couldn't be calculated, as - according to him or her - "the right skid has an unknown arm datum". Therefore the official accident report didn't calculate the actual lateral CoG for this flight. The report ventures however to find that
3.1.5 The helicopter was unduly heavy on the right-hand side skid and the CG was out of the regimen over the skid.
. Maybe taking the skid position from the airframe dimensions graph in the POH is an entirely unscientific approach?
Last edited by Hot and Hi; 21st Mar 2017 at 19:56.
Join Date: May 2010
Location: New Zealand
Age: 52
Posts: 395
Likes: 0
Received 0 Likes
on
0 Posts
John
did you just add the weight of the hippo to the seat weights for the pilot and pax. that would work for the fore and aft CoG, but would be wildly inaccurate for lateral CoG.
Pretty sure those skids stick way out past the body of the 44, and the seat lateral CoG positions are in the center of the seat. If someone with a 44 could measure how far the skids stick out then you could do an accurate lateral CoG and probably find that it is way out of CoG...
did you just add the weight of the hippo to the seat weights for the pilot and pax. that would work for the fore and aft CoG, but would be wildly inaccurate for lateral CoG.
Pretty sure those skids stick way out past the body of the 44, and the seat lateral CoG positions are in the center of the seat. If someone with a 44 could measure how far the skids stick out then you could do an accurate lateral CoG and probably find that it is way out of CoG...
Join Date: Jun 2008
Location: England & Scotland
Age: 63
Posts: 1,413
Likes: 0
Received 0 Likes
on
0 Posts
John
did you just add the weight of the hippo to the seat weights for the pilot and pax. that would work for the fore and aft CoG, but would be wildly inaccurate for lateral CoG.
Pretty sure those skids stick way out past the body of the 44, and the seat lateral CoG positions are in the center of the seat. If someone with a 44 could measure how far the skids stick out then you could do an accurate lateral CoG and probably find that it is way out of CoG...
did you just add the weight of the hippo to the seat weights for the pilot and pax. that would work for the fore and aft CoG, but would be wildly inaccurate for lateral CoG.
Pretty sure those skids stick way out past the body of the 44, and the seat lateral CoG positions are in the center of the seat. If someone with a 44 could measure how far the skids stick out then you could do an accurate lateral CoG and probably find that it is way out of CoG...
I agree entirely. As I said, I simply shared the additional weight front / rear seats. The app I was using (identified) does not have the flexibility to calculate every possible version of stupid; it only allows for weight on seats, either fuel tank or external (central) hook. Likely the fore/aft CofG and the MAUW could have been OK, but the lateral CofG might have been "interesting".
Arm Datum of Skid
The R44 POH shows that the skids are 83 inches apart. That means each skid is + or - 41.5 in off the longitudinal center line.
I created a new station in my R44 W&B application (Co-Pilot for iOS) for "Load on RH skid) with lateral arm of +41.5 in, and longitudinal arm of 79.5 in (same as rear pax).
With this configuration, I arrive at the lat CoG values as per my post above (changing with the estimated weight of the animal handing from the skid):
I created a new station in my R44 W&B application (Co-Pilot for iOS) for "Load on RH skid) with lateral arm of +41.5 in, and longitudinal arm of 79.5 in (same as rear pax).
With this configuration, I arrive at the lat CoG values as per my post above (changing with the estimated weight of the animal handing from the skid):
Lateral envelope is +/- 3 inches. Using the assumptions for fuel, pax and cargo weight (50 kg for the hippo baby) from John R81, the lateral CoG comes out exactly at 3.0 in. Any bigger, like 100 kg as estimated by Thracian, and the lat CoG would be way out (4.6 in). Putting the rear pax on the left side could have helped, but who knows maybe their ops procedures require the loadmaster to keep an eye on the external load
