Plans/Parts for a Prather Spitfire I, Building 1st Hydro...Need Help

[waltr]

This was moved over to help a friend. Any help would also be appreciated.

Group: Members

Posts: 10

Joined: 28-March 07

Member No.: 4,916

HELP PLEASE! I just got a used Prather Spitfire I hull, and I'm looking for help getting the boat set-up. In purchasing the boat, I did not get any of the original plans with it. The hull is together but may be missing some parts. I've seen pics of other Prather Spitfire 1's where trim tabs like pieces were mounted between the sponsons on each side. The hull I got does not have those, and I am wondering if I need them. No fuel tank was included with the hull, and I am not sure of the correct mounting position or size for the tank. I am also looking for help in determining the best set-up for the servos. I've got a K&B 3.5 engine that I intend to run with the boat. Any and all help from anyone who has set one of these hulls up would be greatly appreciated. I am willing to buy any parts that you may have that you don't need and possibly I do need. Please let me know if you can help. Thank you.

--------------------

Pete

Whoop-whoop!

waltr

Hi Pete,

I've got a Spitfire I and II.

Just never seem to run them.

I'll take some pics of the boat and radio box and send em your way.

I believe there's an 8oz.slant tank in it with a 1 oz. hopper tank.

There's a Hitec 645mg steering servo in it that seems to be just fine.

My Spitfire II has the aluminum down force (drag) flaps on the boom tubes,

but my 3.5 boat does not.

Anybody out there know about the flaps on the little boat?

I think a friend of mine might have a manual.I'll ask tomorrow.

Later!

getnoff

Thanks Walt! Wow! Getting an owner's manual would be great. If your friend will let me borrow it, I PROMISE that I WILL return it.

I was wondering about those drag flaps on the boom tubes (is that what they're called?) and I did see a Spitfire I with them for sale on eBay. I had heard from someone else that they're really not necessary on the Spitfire I, although they do look cool.

I am going to use a JR270 for the throttle servo and a JR590M for the steering servo. In looking at the servo mounting set-up in the radio box, I'm going to have to make some modification to get the servos positioned correctly, but I think I've got that one figured out.

I had no idea about the correct size or shape for the fuel tank. I think I saw a pic somewhere where I could see that the fuel tank was an 8oz size, but I wasn't really sure on that. I was just going to find one that fit and go from there. Is a "hopper" tank necessary? I've never used one of those.

Walt, I don't know anything about this hull. I was really thinking I was buying an "outrigger" when I got it. Everyone in my Club right now is hot on riggers for some reason, so I was trying to join the crowd. What's new?! Anyway, is this a "hydro" or "rigger" hull? Once set-up correctly, how does the boat perform? Are they quick? The riggers that the guys in my Club are building are for the most part inboard configurations. How do these outboard hydro/riggers perform?

Do you have any info on how to best set-up the engine, i.e. depth, thrust angle and best props to use, etc.?

Walt, anything you can do to help will be GREATLY appreciated. Once again, thanks for you help and friendship!!! Take care.........

Pete

--------------------

Pete

Whoop-whoop!

 

[waltr]

Hi Pete,

I'm still waiting to find out from my buddy if he has the manual.He said that he knows he has one for the Spitfire II,still looking for the Spitfire I.

The Downforce flaps help the boat to stay on the water instead of blowing off.

I'm sure someone here knows if the 21 is supposed to have them or not.

There not really called drag flaps,I just said that decause they also cause some aero drag.But it's still better than up side down.

Pete,as far as the steering servo,you might want to upgrade it.Outboards require alot stronger servos than an inboard v bottom. I know everyone has different ideas,but a HiTec 645mg has the least amount of strength that I would use.

I think the one you have is only 70oz,and the 645 is 133oz. My 7.5 boats use 2 645s.An outboard tunnel or your rigger o/b should turn much harder than an inboard V bottom.

One of the biggest problems with the outboards is when, not if, when you blow it over and the motor hits the water hard,it will tear a light servo right up.Then you'll be buying a stronger one anyway.

My 21 Lynxs use an Airtronics servo thats around 200 oz. They're suggested in the owners manuals.

Motor setup.

A normal starting point for me on an outboard is 1* negative and the center line of the propshaft level with the bottom of the boat.Than during testing,adjust the trim for best nose attitude.Then raise the motor just a 1/16th" at a time.once,twice and possably a 3rd time.Not to excede 3/16ths up.

And it is technically a rigger.A rigger is just a form of a hydro. They're outrigger hydros.

It'll be fun and should be a bit quicker than an outboard tunnel with the SAME power. I'm guessing that that throttle exhaust motor came with the Spitfire.A common package years back.

As for it running with 21 inboard outriggers,don't get your hopes up.Just not going to happen.

You'll have to watch a good 21 rigger run. It'll surprise you how fast they are and how they rip around the course.They'll run an honest mid 60's to mid 70s around the course and mostly if not all the time WOT.(wide open throttle).

A good inboard rigger is an absolute rush to run. Handling and speed.it's all there.

I still have to get you some pics.Went to do it last night,but my battery was depleted.All charged now,so,later I'll try again.

That'll get you started.

Good luck

 

[Pete Markese]

This was moved over to help a friend. Any help would also be appreciated.

Group: Members

Posts: 10

Joined: 28-March 07

Member No.: 4,916

HELP PLEASE! I just got a used Prather Spitfire I hull, and I'm looking for help getting the boat set-up. In purchasing the boat, I did not get any of the original plans with it. The hull is together but may be missing some parts. I've seen pics of other Prather Spitfire 1's where trim tabs like pieces were mounted between the sponsons on each side. The hull I got does not have those, and I am wondering if I need them. No fuel tank was included with the hull, and I am not sure of the correct mounting position or size for the tank. I am also looking for help in determining the best set-up for the servos. I've got a K&B 3.5 engine that I intend to run with the boat. Any and all help from anyone who has set one of these hulls up would be greatly appreciated. I am willing to buy any parts that you may have that you don't need and possibly I do need. Please let me know if you can help. Thank you.

--------------------

Pete

Whoop-whoop!

waltr

Hi Pete,

I've got a Spitfire I and II.

Just never seem to run them.

I'll take some pics of the boat and radio box and send em your way.

I believe there's an 8oz.slant tank in it with a 1 oz. hopper tank.

There's a Hitec 645mg steering servo in it that seems to be just fine.

My Spitfire II has the aluminum down force (drag) flaps on the boom tubes,

but my 3.5 boat does not.

Anybody out there know about the flaps on the little boat?

I think a friend of mine might have a manual.I'll ask tomorrow.

Later!

getnoff

Thanks Walt! Wow! Getting an owner's manual would be great. If your friend will let me borrow it, I PROMISE that I WILL return it.

I was wondering about those drag flaps on the boom tubes (is that what they're called?) and I did see a Spitfire I with them for sale on eBay. I had heard from someone else that they're really not necessary on the Spitfire I, although they do look cool.

I am going to use a JR270 for the throttle servo and a JR590M for the steering servo. In looking at the servo mounting set-up in the radio box, I'm going to have to make some modification to get the servos positioned correctly, but I think I've got that one figured out.

I had no idea about the correct size or shape for the fuel tank. I think I saw a pic somewhere where I could see that the fuel tank was an 8oz size, but I wasn't really sure on that. I was just going to find one that fit and go from there. Is a "hopper" tank necessary? I've never used one of those.

Walt, I don't know anything about this hull. I was really thinking I was buying an "outrigger" when I got it. Everyone in my Club right now is hot on riggers for some reason, so I was trying to join the crowd. What's new?! Anyway, is this a "hydro" or "rigger" hull? Once set-up correctly, how does the boat perform? Are they quick? The riggers that the guys in my Club are building are for the most part inboard configurations. How do these outboard hydro/riggers perform?

Do you have any info on how to best set-up the engine, i.e. depth, thrust angle and best props to use, etc.?

Walt, anything you can do to help will be GREATLY appreciated. Once again, thanks for you help and friendship!!! Take care.........

Pete

--------------------

Pete

Whoop-whoop!

Boy, am I having a fit trying to get this Spitfire on plane! I've tried numerous prop depths and thrust angles and none of them seem to work. I moved the prop depth all the way to the top of the engine mounts capability and all the way to the bottom. On one extreme the prop shaft is 3/4" above C/L and on the same on the other extreme. I move the thrust angle from full negative to full positive and again can't find the right setting! I've currently got a 1740/3 prop mounted.

I know this hull requires a healthy launch, but unfortunately I am doing this without a pit crew, so I am doing my best with handling the tx and launch together. In any case, I have gotten it to almost get up on plane a couple of times, but I am now so confused that I don't know if that was just a lucky launch angle or if it was truly some change in either prop depth or thrust angle that accomplished that.

Should I try a different prop? Is it the launch angle? Everyone always says that a good starting point for prop depth is approx. 1/8" above C/L. I've been there and everywhere above and below that starting point, but the boat either cavitates badly or just girgles without hardly moving! It will pop up like it wants to get up on the water's surface, but it just never makes it!

Does anyone have any suggestions that might help? If so, PLEASE give them to me. I'm at my wits end!

Pete

 

[Pete Markese]

Well success! I got the Spitfire on plane today! I found a prop depth and thrust angle that the boat liked. and it finally ran really well. I don't know if this is the best set-up, but I'm hanging with it for a while since that boat's running across the pond at speed.

Set-up that worked.....changed prop to a x440; prop depth 1/8" below C/L; thrust angle 1 degree positive. I probably feel the prop change was the big difference. I had a 1740/3 on her previously, and I believe I just couldn't get the launch correct, especially with that prop.

In any case, we finally had a successful run!!!