22TDI Engine Placement Questions

gone7
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22TDI Engine Placement Questions

Post by gone7 » May 5th, 2012, 10:29 pm

Hey Bryan,

I've noticed on your 22TDI that you've mounted the engine down into the rear deck quite a bit and I have a few questions regarding this. I'm curious if you've had any difficulties with oil changes down at that level since the drain/oil pan may be harder to get to? Do you use a dipstick pump for changing the oil? And, did you feel the need to install a bilge pump in that compartment beneath the motor or did you just add a drain plug to clear out any water that might collect in there?

Thanks,
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bphillip2
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Re: 22TDI Engine Placement Questions

Post by bphillip2 » May 7th, 2012, 6:55 am

Please don't copy everything you see. This engine placement would create problems with fumes on a gas engine, besides the belts in the kit won't reach.

I have a bilge pump, kind of a pain. I don't change oil, the customer does :) It would be done with a standard boat oil extractor, the dipstick tube comes off on this engine.

gone7
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Re: 22TDI Engine Placement Questions

Post by gone7 » May 7th, 2012, 9:08 am

Hehehe...alright I won't copy everything. ;) What I have in mind will actually be quite a bit different from the 22TDI. I'm still developing my plan for the engine deck. One of my considerations is in trying to limit my over-all height of the craft which mainly has to do with the prop and guard. My main focus for the craft will be river running and one of the biggest limitations where I'm located is bridges. Trying to find suitable stretches of river that aren't blocked by a low bridge at some point has become a challenge. I was out rafting this past weekend and actually measuring bridge clearances.

I want to lower the thrust prop as much as possible to take advantage of whatever river channels that may be even marginally suitable. I have the 84" prop. And since you've mentioned the belt that comes with the kit, I may actually want to go to a shorter belt.

I'm thinking if I have the bottom of the prop about 5" above the rear skirt attachment line I should be safe from water strikes. It seems like that skirt attachment line kinda marks the waterline of the craft at rest. What do you think?
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bandit1538
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Re: 22TDI Engine Placement Questions

Post by bandit1538 » May 7th, 2012, 9:30 pm

gone7 wrote:Hehehe...alright I won't copy everything. ;) What I have in mind will actually be quite a bit different from the 22TDI. I'm still developing my plan for the engine deck. One of my considerations is in trying to limit my over-all height of the craft which mainly has to do with the prop and guard. My main focus for the craft will be river running and one of the biggest limitations where I'm located is bridges. Trying to find suitable stretches of river that aren't blocked by a low bridge at some point has become a challenge. I was out rafting this past weekend and actually measuring bridge clearances.

I want to lower the thrust prop as much as possible to take advantage of whatever river channels that may be even marginally suitable. I have the 84" prop. And since you've mentioned the belt that comes with the kit, I may actually want to go to a shorter belt.

I'm thinking if I have the bottom of the prop about 5" above the rear skirt attachment line I should be safe from water strikes. It seems like that skirt attachment line kinda marks the waterline of the craft at rest. What do you think?

Hay Guy, maybe you might want to do what I'm planning to do with my Prospector when I get the time to finish it, I also have a bridge I won't be able to get under with high tide & high water, I plan to run two 48" props, I know it'll make more noise but it's either that or not be able to use it at times, besides counter rotating props also have the "cool" factor. ;)
Pat
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gone7
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Re: 22TDI Engine Placement Questions

Post by gone7 » May 7th, 2012, 10:25 pm

Sounds like a good alternative Pat. I've already purchased my big ol' Ivo "Airboat Paddle" though. I think I'll be alright if I can just lower the profile a bit. I believe there's some room to do that on the Explorer. I'll look forward to seeing your twin prop model. That should be a cool look!
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highlandhovercraft
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Re: 22TDI Engine Placement Questions

Post by highlandhovercraft » May 9th, 2012, 12:29 pm

Twin props sounds good.

Would they generate enough thrust? Just thinking by using 48" props how much of the air is going to get blocked by the lift fan bay & engine?

Reason I say that is that I had a problem with thrust on my surveyor until I removed the engine cover. I increased thrust by 26% just by chucking the large engine cover away.

I would like to have a lower rear end on the explorer I'm building and thinking about the props wouldn't take too much engineering to make up a twin thrust drive .

I just worry that if it didn't work that it would be a lot of time & money down the drain.

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Re: 22TDI Engine Placement Questions

Post by bandit1538 » May 9th, 2012, 2:21 pm

highlandhovercraft wrote:Twin props sounds good.

Would they generate enough thrust? Just thinking by using 48" props how much of the air is going to get blocked by the lift fan bay & engine?

Reason I say that is that I had a problem with thrust on my surveyor until I removed the engine cover. I increased thrust by 26% just by chucking the large engine cover away.

I would like to have a lower rear end on the explorer I'm building and thinking about the props wouldn't take too much engineering to make up a twin thrust drive .

I just worry that if it didn't work that it would be a lot of time & money down the drain.

You know, I'm not really sure, but I should know or someone will tell me by the time I get serious about finishing it, if not then at high water I'll have to drive 10 miles farther to the next ramp and have to pay to launch, the one I use now is free.
Pat
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Re: 22TDI Engine Placement Questions

Post by bphillip2 » May 10th, 2012, 7:54 am

Simply stacking props on top of each other is not "2 props", that is adding more blades. A prop manufacturers dream come true. Disc area is the key, not more blades. Two 5 foot props side by side would be the same as a seven.

bandit1538
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Re: 22TDI Engine Placement Questions

Post by bandit1538 » May 10th, 2012, 11:34 am

bphillip2 wrote:Simply stacking props on top of each other is not "2 props", that is adding more blades. A prop manufacturers dream come true. Disc area is the key, not more blades. Two 5 foot props side by side would be the same as a seven.

I guess I should have made that more clear, :oops: what I meant was counter rotating side by side, 48" props so that I'm not over width, and with the prop guards I would be right at 8' 6" to keep it legal.
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Re: 22TDI Engine Placement Questions

Post by jchovernut » May 12th, 2012, 8:14 pm

I believe the 'classic' Explorer plans, and its predecessors, the 'Model-A,' & 'Model-B' all had twin 72" props. If turned to the right angle, they'd be inside trailering width, and the design incorporated folding outboard prop guards for trailering as well. I always thought the twin prop look and sound was rather cool. But after the Alaska trip and operating with Bryan around the Puget Sound, the single 84" sure seems a lot safer and more manageable. But...if you need the clearance, Clarance, twins might do the trick.

Pat, how do you plan on getting the props to counter-rotate? Do you plan on 'figure-8'ing' the drive belt on one side? I've never seen such a thing on a hover. The Piper Seminole twin-engine airplane I got my multi-rating in had counter-rotating props, but the bass-ackwards engine was actually designed to run that way. Most twins run in the same direction.

Guy, I can attest the bilge pump is a PITA to get to ;) Other than going to the twin props to lower overall height, you could always 'kneel' under the bridges by dumping lift and 'airboating' under the bridges. Or possibly even carry a small trolling motor to hang over the side or bow to thrust the hover under the obstruction while in 'displacement mode.'

Cheers,
John Carter
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