LoPresti's Spectra Aircraft

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Pilot-34

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I wonder if the belt drive was easier to work out than a shaft drive ?
 

Blackhawk

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How did the landing gear retract?
It didn't; it had fixed landing gear and they removed it for the water testing.

The project never got around to installing proper retracting landing gear for land and sea operation.

I wonder if the belt drive was easier to work out than a shaft drive ?
I don't think the belt drives were succesful, that's why they changed to a mid tractor pylon.
 

Pilot-34

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You are probably correct.
But that still leaves the question open of belt drive versus shaft drive.
Is the belt drive easier to achieve that a shaft drive?
Is it lighter or more efficient?
Or was it simply the location of the propellers when shaft driven did not work out well?
Don’t you love how one question creates two or three more?
 

crusty old aviator

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There’s a Canadian homebuilt amphib that was designed and built in the 60’s, IIRC, called the Blue Teal. She was listed in Janes. Ken Gamble, in Ontario, owned her for several years before someone noticed her and agreed to his price, some time in the early 80’s. She was similar to the Taylor Coot, but smaller.
 

BJC

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It didn't; it had fixed landing gear and they removed it for the water testing.
The project never got around to installing proper retracting landing gear for land and sea operation.
That is what it looks like in the photo. A retract system would have added weight and drag.


BJC
 

Puggo1

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hi, the oz amphibian was designed by my Sydney university professors. It was in the workshops once and what I saw of the belts is that they were wide (4"?) and long. I suspect that as the long belt heated up it lost tension. It generated my lifelong interest in aircraft design. One day I'll design and build a diesel cruiser.
 

Pilot-34

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hi, the oz amphibian was designed by my Sydney university professors. It was in the workshops once and what I saw of the belts is that they were wide (4"?) and long. I suspect that as the long belt heated up it lost tension. It generated my lifelong interest in aircraft design. One day I'll design and build a diesel cruiser.
Interesting !I’ve worked with a lot of belt drives and large machinery i’ve never seen one that didn’t have some sort of tension pulley because it just that issue.
 

tdfsks

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hi, the oz amphibian was designed by my Sydney university professors. It was in the workshops once and what I saw of the belts is that they were wide (4"?) and long. I suspect that as the long belt heated up it lost tension. It generated my lifelong interest in aircraft design.
Kim White, who was responsible for most of the detail design of the FSRW (and the W in the name) is still around but is more or less retired now. I know him well. I am pretty sure they installed tensioners on the belts at some point. In the end, the two propellers, associated drive system and buried engine were just too heavy and they went to the single, high mounted tractor engine to try to get the weight down. I think Kim also told me they had issues with spray given the aft location of the props in the twin prop configuration. It has been a while since I talked to him about the project. Kim still lectures part time at the university and his practical approach to teaching is, by all accounts, a hit with the students.

Also, the comment in one of the attachments about this aircraft having two registrations needs some clarification. The aircraft was registered as VH-XWS. The second registration is not a N aircraft registration but a boat registration. All amphibians in Australia must also be registered as a boat.

Finally here is an article on the FSRW from Homebuilt Aircraft Magazine, January 1984
IMG_8654.JPGIMG_8655.JPGIMG_8656.JPGIMG_8657.JPG
 
Last edited:

Blackhawk

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I started designig an amphibian based on the LaPresti Spectra as a two seat for our ultralight category at 544kg plus the amphib allowance; 30kg

Soon we could go to 700kg

I bought a set of RC plans for the Spectra back in 2007 and scaled it up to what I expected the correct size for a 2 seat version would be.

This was as far as I got. (work always interfer's with the more important thing's) spec's are just estimates.

WhitePointer Amphibian LSA concept.png
 

tdfsks

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Nice looking design ... how was it intended to be built ? Composite ? Metal ? Just need to make sure it costs much less than an ICON A5 !!

There are a couple of Seawind 3000's down south. One in Sydney.
 

tdfsks

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The Airshark was mentioned above. Here is an old article on it from Kitplanes in April 1986. It was a nice looking machine.

Sorry if the photos are not the best but they are as good as I can do without breaking the spine of a fragile old magazine.
IMG_8658.JPGIMG_8659.JPGIMG_8660.JPGIMG_8661.JPGIMG_8662.JPG
 

Riggerrob

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Sep 9, 2014
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Canada
Dear Blackpoint,
Your Whitepointer sketches are pretty, but may I suggest a couple of ways to improve pitch stability?
First, consider that both the Lopresti prototype and Seawind were planned as 4-seaters. That long gap - between pilots' seats and wing - was intended for a secon row of seats. If you move the pilots' seats back close to the wings' leading edge, you can vastly simplify balance.
Secondly, if you extend the horizontal tail farther aft - on a boom - your airplane will be far more stable in pitch. It will also enjoy greater elevator authority.
 

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