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  #16  
Old 12-05-2011, 06:45 PM
u4ea32's Avatar
u4ea32 u4ea32 is offline
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I am surprised that the red boat in the first post looks so very, very far from a reasonable aerodynamic configuration (hard to imagine more aero "wetted surface"), and seems pretty darn pedestrian underneath compared to the run-of-the-mill Miss Budweiser (kinda a smiley there, but Miss B has been around for a long time).

Correct me if I'm wrong, I probably am, as I have never been involved in any serious powerboat speed record efforts. For example, I'm so ignorant that I don't even know if you must use a propellor instead of purely the in-air thrust of the jet engine, on a world speed record run. It sounds like a propellor is not needed, as several attempts have used aircraft jet engines and even rockets.

It seems to me, from what I've read, that the key issues in a speed record boat are aerodynamic at speeds over about 100-150 knots. Hence, I would expect that a record boat would really be an airplane with something that happens to stay in contact with the water most of the time. The lack of longitudinal control has always surprised me. That T-tail business is on the wrong end: what kills the driver is bow lift, not tail lift. And lifting the tail when in a blow over simply wont work -- that's why jet airplanes have stick shakers and pushers (stall blankets the tail surfaces preventing recovery).

Also, the lack of roll or yaw control seems a serious deficiency at record speeds. According to Wikipedia, everyone has died due to a lack of pitch or roll control so far. So why the lack of decent aero controls?

Why are the record boats so different from airplanes? I mean, not the lack of wheels or passenger seats, but in the control, lift, and propulsion domains. A canard seems far more appropriate than control surfaces on the tail, but Rutan has been demonstrating that concept for decades, so its certainly not unknown in airplanes. So why not something more like a Veri-Eze?

For example, any emphasis on the bottom shape seems silly. At 300 MPH, nothing needs to be in the water, the boat will be supported by air. This happens in run-of-the-mill 100 knot tunnel boats already.

Looking at the death traps, they all seem to have the same problems: no decent aerodynamic controls. Bluebird looks like an airplane with the control surfaces removed. Anyone would call you an idiot if you tried to fly around in a jet plane without aerodynamic controls!
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  #17  
Old 12-05-2011, 06:52 PM
FranklinRatliff FranklinRatliff is offline
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Quote:
Originally Posted by u4ea32 View Post
I am surprised that the red boat in the first post looks so very, very far from a reasonable aerodynamic configuration (hard to imagine more aero "wetted surface"), and seems pretty darn pedestrian underneath compared to the run-of-the-mill Miss Budweiser (kinda a smiley there, but Miss B has been around for a long time).

Correct me if I'm wrong, I probably am, as I have never been involved in any serious powerboat speed record efforts. For example, I'm so ignorant that I don't even know if you must use a propellor instead of purely the in-air thrust of the jet engine, on a world speed record run. It sounds like a propellor is not needed, as several attempts have used aircraft jet engines and even rockets.

It seems to me, from what I've read, that the key issues in a speed record boat are aerodynamic at speeds over about 100-150 knots. Hence, I would expect that a record boat would really be an airplane with something that happens to stay in contact with the water most of the time. The lack of longitudinal control has always surprised me. That T-tail business is on the wrong end: what kills the driver is bow lift, not tail lift. And lifting the tail when in a blow over simply wont work -- that's why jet airplanes have stick shakers and pushers (stall blankets the tail surfaces preventing recovery).

Also, the lack of roll or yaw control seems a serious deficiency at record speeds. According to Wikipedia, everyone has died due to a lack of pitch or roll control so far. So why the lack of decent aero controls?

Why are the record boats so different from airplanes? I mean, not the lack of wheels or passenger seats, but in the control, lift, and propulsion domains. A canard seems far more appropriate than control surfaces on the tail, but Rutan has been demonstrating that concept for decades, so its certainly not unknown in airplanes. So why not something more like a Veri-Eze?

For example, any emphasis on the bottom shape seems silly. At 300 MPH, nothing needs to be in the water, the boat will be supported by air. This happens in run-of-the-mill 100 knot tunnel boats already.

Looking at the death traps, they all seem to have the same problems: no decent aerodynamic controls. Bluebird looks like an airplane with the control surfaces removed. Anyone would call you an idiot if you tried to fly around in a jet plane without aerodynamic controls!
There are no rules against aerodynamic controls. I know because I checked the UIM rulebook.

http://frodesblog.com/big-accident-in-key-west/

Other boats could also use aerodynamic controls.
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