Advise for buildin aluminium hull.

Airboats with smaller powerplants.
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M0RYAK
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Re: Advise for buildin aluminium hull.

Postby M0RYAK » Tue Sep 04, 2018 2:01 am

My engine.
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Slidin Gator
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Re: Advise for buildin aluminium hull.

Postby Slidin Gator » Tue Sep 04, 2018 9:06 pm

Moryak,
After re-reading your earlier posts, I find the following for info:
M0RYAK wrote:I will use engine from motorcycle Honda CBR1100XX with gear box - 150 HP, max rpm 11000. I have possibility use reduction 5.1 or 3.4. I think cruise rpm will be 7000-8000, but sometimes i can increase until 11000.

M0RYAK wrote:My engine wight - 190 lbs,Hull - 360 lbs, plus 2 peopls - 240 lbs each, fuel - 50 ltrs, eqipment about 100 lbs. Total about - 1200 lbs.

I also did the minimum amount of research into the engine, in other words I looked at wikipedia...
https://en.wikipedia.org/wiki/Honda_CBR1100XX


I assume the 190 lbs includes the gear box, with 150 +/- hp you will have a great power to weight package!

As for gear ratios, keep in mind that you are going to need to settle on a single gear ratio. Even if you can manage to shift on the fly, the difference between 1st and 2nd is too much to spin a given prop with a fixed pitch over the speed range you will achieve (even 50+ mph).

You can pretty much forget about the 5.1:1 first gear. That ratio would be good to drive a monster prop for pulling a plow, but it won't meet your stated goal of high speed on open water.
11,000/5.1 = 2,157 prop RPM (applicable to a 75". 1,900 mm or larger prop).

The 3.4 ratio is about right to match your needs, but given that information I think you should consider a smaller prop diameter (69") and 4 blades. The smaller diameter prop will give you a higher top end speed.

8000/3.4 = 2,353 prop RPM (good match to the 69", 1,750 mm prop for a cruise RPM)
9,350/3.4 = 2,750 prop RPM (applicable to the 71", 1,800 mm prop)
9,520/3.4 = 2,800 prop RPM (applicable to the 69", 1,750 mm prop)
11,000/3.4 = 3,325 prop RPM, (too high for any prop of a reasonable size)

I suggest you call the prop vendor to discuss your specific application further.
https://aeroprop.aero/en/
I grew up thinking that I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540. A Bob Stossel original, still running strong.

Gary S
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Re: Advise for buildin aluminium hull.

Postby Gary S » Wed Sep 05, 2018 7:43 am

Your not taking into consideration what the final gear ratio is going to be.

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Slidin Gator
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Re: Advise for buildin aluminium hull.

Postby Slidin Gator » Wed Sep 05, 2018 11:37 am

Gary S wrote:Your not taking into consideration what the final gear ratio is going to be.

You are correct if the chain drive is included, but that does not appear to be the case. From the picture I see a spider coupling direct off the gear box. Moryak said he does not intend to use a belt drive, so I believe the plan is to couple the gear box output direct to the prop shaft via some type of drive shaft.

Could be wrong, Moryak can advise more details.
I grew up thinking that I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540. A Bob Stossel original, still running strong.

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M0RYAK
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Joined: Wed Aug 15, 2018 3:13 pm

Re: Advise for buildin aluminium hull.

Postby M0RYAK » Wed Sep 05, 2018 12:23 pm

Slidin Gator wrote:Moryak,
After re-reading your earlier posts, I find the following for info:
M0RYAK wrote:I will use engine from motorcycle Honda CBR1100XX with gear box - 150 HP, max rpm 11000. I have possibility use reduction 5.1 or 3.4. I think cruise rpm will be 7000-8000, but sometimes i can increase until 11000.

M0RYAK wrote:My engine wight - 190 lbs,Hull - 360 lbs, plus 2 peopls - 240 lbs each, fuel - 50 ltrs, eqipment about 100 lbs. Total about - 1200 lbs.

I also did the minimum amount of research into the engine, in other words I looked at wikipedia...
https://en.wikipedia.org/wiki/Honda_CBR1100XX


I assume the 190 lbs includes the gear box, with 150 +/- hp you will have a great power to weight package!

As for gear ratios, keep in mind that you are going to need to settle on a single gear ratio. Even if you can manage to shift on the fly, the difference between 1st and 2nd is too much to spin a given prop with a fixed pitch over the speed range you will achieve (even 50+ mph).

You can pretty much forget about the 5.1:1 first gear. That ratio would be good to drive a monster prop for pulling a plow, but it won't meet your stated goal of high speed on open water.
11,000/5.1 = 2,157 prop RPM (applicable to a 75". 1,900 mm or larger prop).

The 3.4 ratio is about right to match your needs, but given that information I think you should consider a smaller prop diameter (69") and 4 blades. The smaller diameter prop will give you a higher top end speed.

8000/3.4 = 2,353 prop RPM (good match to the 69", 1,750 mm prop for a cruise RPM)
9,350/3.4 = 2,750 prop RPM (applicable to the 71", 1,800 mm prop)
9,520/3.4 = 2,800 prop RPM (applicable to the 69", 1,750 mm prop)
11,000/3.4 = 3,325 prop RPM, (too high for any prop of a reasonable size)

I suggest you call the prop vendor to discuss your specific application further.
https://aeroprop.aero/en/


Thanks!

I sent request to "AERO" 2 weeks ago, but answer not received.

I have answer from same small factory. See below:

P.S. Just all factories make props for airplanes (speed more 80 miles).
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Last edited by M0RYAK on Wed Sep 05, 2018 1:33 pm, edited 1 time in total.

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M0RYAK
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Re: Advise for buildin aluminium hull.

Postby M0RYAK » Wed Sep 05, 2018 1:15 pm

Gary S wrote:Your not taking into consideration what the final gear ratio is going to be.


Sorry? I will not use belt or chain reduction, only gearbox of motorcycle.

Like thise:
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Slidin Gator
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Re: Advise for buildin aluminium hull.

Postby Slidin Gator » Thu Sep 06, 2018 12:13 am

Moryak,
That is a very interesting chart. Given your power to weight ratio, I'm pretty confidant that 50-60 MPH+ (80-100 km/hr) high speed cruise is where this set up is going. What I note is that the prop chart you have so far shows prop at minimum efficiency right in the speed range of interest. Talk to the prop vendors about options to move the efficiency curve to peak around 90 km/hr and see if there are options to maximize your top end speed.

This is all getting ahead of the game, but it bounds the prop size. I suggest you design to accommodate a 72", 1,800 mm prop and proceed with the boat/hull layout. You can always go smaller on the prop, which I think you need. Designing for the larger prop design just leaves your options open for the future.
I grew up thinking that I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540. A Bob Stossel original, still running strong.

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M0RYAK
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Posts: 34
Joined: Wed Aug 15, 2018 3:13 pm

Re: Advise for buildin aluminium hull.

Postby M0RYAK » Thu Sep 06, 2018 1:46 am

Slidin Gator wrote:Moryak,
That is a very interesting chart. Given your power to weight ratio, I'm pretty confidant that 50-60 MPH+ (80-100 km/hr) high speed cruise is where this set up is going. What I note is that the prop chart you have so far shows prop at minimum efficiency right in the speed range of interest. Talk to the prop vendors about options to move the efficiency curve to peak around 90 km/hr and see if there are options to maximize your top end speed.

This is all getting ahead of the game, but it bounds the prop size. I suggest you design to accommodate a 72", 1,800 mm prop and proceed with the boat/hull layout. You can always go smaller on the prop, which I think you need. Designing for the larger prop design just leaves your options open for the future.


I understood. I try to tolk with the prop vendors.

From prop chart abow I see what 4 blades prop had more efficiency than 3 blades prop in static, but in speed 90 km/h efficiency agree.

Speed 50-60 MPH it is very good, I hope 40-45 MPH.

I think 4 blades prop have big plus - In case of damage some blades I can make 2 blades prop.

P.S. My friend's brother have boat with 4 blades prop (same engine), He like it.
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Slidin Gator
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Re: Advise for buildin aluminium hull.

Postby Slidin Gator » Mon Sep 10, 2018 9:23 pm

M0RYAK wrote:I think 4 blades prop have big plus - In case of damage some blades I can make 2 blades prop.

Been there done that. All other things being equal, 4 is better than 3 for that very reason. I run wide 2 blade props, so I have to settle for a spare set in the truck, just need a ride to the ramp.
I grew up thinking that I-10 was the Mason Dixon line.
1986 Airboat Engineering Inc., 14' Marsh Master. Refreshed narrow deck, SV O-540. A Bob Stossel original, still running strong.

User avatar
M0RYAK
Southern Airboat Member
Posts: 34
Joined: Wed Aug 15, 2018 3:13 pm

Re: Advise for buildin aluminium hull.

Postby M0RYAK » Mon Sep 10, 2018 11:41 pm

Slidin Gator wrote:
M0RYAK wrote:I think 4 blades prop have big plus - In case of damage some blades I can make 2 blades prop.

Been there done that. All other things being equal, 4 is better than 3 for that very reason. I run wide 2 blade props, so I have to settle for a spare set in the truck, just need a ride to the ramp.


Thanks! Understood.

I was Talk to the prop vendors about options and I have only possibility choose diameter of props, for 4 blade - max 70" and wide middle part of the blade - 4,5".
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