45 Crapshooter

[Nigtmare]

what is everyone have for a strut angel on a 45 shooter, I run about a one deg. negative and even with the bottom of the rear sponsons :unsure:

Thanks. Nick

 

[Speed Jr.]

I ran flat and even with sponsons.... With only one shim under rear boom. Was pretty close...

Jr.

 

[Marty Davis]

what is everyone have for a strut angel on a 45 shooter, I run about a one deg. negative and even with the bottom of the rear sponsers :unsure:

Thanks. Nick

Nick:

GREAT TOPIC !!

Interesting things about strut angle and Why do you want strut angle?

Strut angle does a couple things. It allows for an easier launch (bigger pitch props). It also assists in acceleration out of the turns. Makes it easier for the engine to accelerate the boat. Why, because it allows the rear of the boat to jump up on the tips of the prop where the high pitch area is.

How much strut angle to use......

You want as much angle as possible WITHOUT the rear of the boat picking up a "High Frequency Hop". You will have to look very closely at the rear of the boat at full speed to see if you see ANY high frequency hop.

As an example, on my 20 boat I use 1.3 degrees of angle. That is the perfect angle to help launch and acceleration WITHOUT High Frequency Hop.

Is it the same for all boats...?? NO, it has to do with a lot of variables including strut weight, prop, CG, rear sponson attack angle and probably some more. Maybe dynamic cg too.

So, it is dependent on the specific boat and you can tune it at the pond by looking very closely during full speed pass down the front straightaway.

What kind of boat is it most important on? The more strut weight the more improtant. For example, a heavy tail weight (rear wing boat) 1/8 scale boat it is CRITICAL the angle on the strut. This will be thing that will keep the boat from dropping the rear of the boat in the turns and help it accelerate out of the turns. The heavier the strut weight, the higher the angle you will need on the strut.

Probably more than you wanted, but important enough to put in the archives of IW. This is a KEY COMPONENT of a great running boat of any kind.

 

[CapeTown73]

what is everyone have for a strut angel on a 45 shooter, I run about a one deg. negative and even with the bottom of the rear sponsers :unsure:

Thanks. Nick

Nick:

GREAT TOPIC !!

Interesting things about strut angle and Why do you want strut angle?

Strut angle does a couple things. It allows for an easier launch (bigger pitch props). It also assists in acceleration out of the turns. Makes it easier for the engine to accelerate the boat. Why, because it allows the rear of the boat to jump up on the tips of the prop where the high pitch area is.

How much strut angle to use......

You want as much angle as possible WITHOUT the rear of the boat picking up a "High Frequency Hop". You will have to look very closely at the rear of the boat at full speed to see if you see ANY high frequency hop.

As an example, on my 20 boat I use 1.3 degrees of angle. That is the perfect angle to help launch and acceleration WITHOUT High Frequency Hop.

Is it the same for all boats...?? NO, it has to do with a lot of variables including strut weight, prop, CG, rear sponson attack angle and probably some more. Maybe dynamic cg too.

So, it is dependent on the specific boat and you can tune it at the pond by looking very closely during full speed pass down the front straightaway.

What kind of boat is it most important on? The more strut weight the more improtant. For example, a heavy tail weight (rear wing boat) 1/8 scale boat it is CRITICAL the angle on the strut. This will be thing that will keep the boat from dropping the rear of the boat in the turns and help it accelerate out of the turns. The heavier the strut weight, the higher the angle you will need on the strut.

Probably more than you wanted, but important enough to put in the archives of IW. This is a KEY COMPONENT of a great running boat of any kind.

Hi Marty,

Thanks for sharing this valuable info with us. There are many of us who simply don't know about these settings and effects , and we learn with each post like yours above. We are just starting to run riggers here so it's all new to us !

Thanks again,

Wennie, Cape Town, South Africa.

 

[Don Ferrette]

what is everyone have for a strut angel on a 45 shooter, I run about a one deg. negative and even with the bottom of the rear sponsers :unsure:

Thanks. Nick

Nick:

GREAT TOPIC !!

Interesting things about strut angle and Why do you want strut angle?

Strut angle does a couple things. It allows for an easier launch (bigger pitch props). It also assists in acceleration out of the turns. Makes it easier for the engine to accelerate the boat. Why, because it allows the rear of the boat to jump up on the tips of the prop where the high pitch area is.

How much strut angle to use......

You want as much angle as possible WITHOUT the rear of the boat picking up a "High Frequency Hop". You will have to look very closely at the rear of the boat at full speed to see if you see ANY high frequency hop.

As an example, on my 20 boat I use 1.3 degrees of angle. That is the perfect angle to help launch and acceleration WITHOUT High Frequency Hop.

Is it the same for all boats...?? NO, it has to do with a lot of variables including strut weight, prop, CG, rear sponson attack angle and probably some more. Maybe dynamic cg too.

So, it is dependent on the specific boat and you can tune it at the pond by looking very closely during full speed pass down the front straightaway.

What kind of boat is it most important on? The more strut weight the more improtant. For example, a heavy tail weight (rear wing boat) 1/8 scale boat it is CRITICAL the angle on the strut. This will be thing that will keep the boat from dropping the rear of the boat in the turns and help it accelerate out of the turns. The heavier the strut weight, the higher the angle you will need on the strut.

Probably more than you wanted, but important enough to put in the archives of IW. This is a KEY COMPONENT of a great running boat of any kind.

What Marty says is definitely true and to expand on it a little further you can get to the point that too much negative strut angle starts to waste energy pushing the back of a boat up that would be better spent pushing it forward.

 

[steve wood]

what is everyone have for a strut angel on a 45 shooter, I run about a one deg. negative and even with the bottom of the rear sponsers :unsure:

Thanks. Nick

Nick:

GREAT TOPIC !!

Interesting things about strut angle and Why do you want strut angle?

Strut angle does a couple things. It allows for an easier launch (bigger pitch props). It also assists in acceleration out of the turns. Makes it easier for the engine to accelerate the boat. Why, because it allows the rear of the boat to jump up on the tips of the prop where the high pitch area is.

How much strut angle to use......

You want as much angle as possible WITHOUT the rear of the boat picking up a "High Frequency Hop". You will have to look very closely at the rear of the boat at full speed to see if you see ANY high frequency hop.

As an example, on my 20 boat I use 1.3 degrees of angle. That is the perfect angle to help launch and acceleration WITHOUT High Frequency Hop.

Is it the same for all boats...?? NO, it has to do with a lot of variables including strut weight, prop, CG, rear sponson attack angle and probably some more. Maybe dynamic cg too.

So, it is dependent on the specific boat and you can tune it at the pond by looking very closely during full speed pass down the front straightaway.

What kind of boat is it most important on? The more strut weight the more improtant. For example, a heavy tail weight (rear wing boat) 1/8 scale boat it is CRITICAL the angle on the strut. This will be thing that will keep the boat from dropping the rear of the boat in the turns and help it accelerate out of the turns. The heavier the strut weight, the higher the angle you will need on the strut.

Probably more than you wanted, but important enough to put in the archives of IW. This is a KEY COMPONENT of a great running boat of any kind.

and .100° will make a difference. no this is not a typo

 

[Andy Brown]

.100 degree? Or .1 degree? What tool do you use to measure .100 degree?

 

[Nigtmare]

what is everyone have for a strut angel on a 45 shooter, I run about a one deg. negative and even with the bottom of the rear sponsers :unsure:

Thanks. Nick

Nick:

GREAT TOPIC !!

Interesting things about strut angle and Why do you want strut angle?

Strut angle does a couple things. It allows for an easier launch (bigger pitch props). It also assists in acceleration out of the turns. Makes it easier for the engine to accelerate the boat. Why, because it allows the rear of the boat to jump up on the tips of the prop where the high pitch area is.

How much strut angle to use......

You want as much angle as possible WITHOUT the rear of the boat picking up a "High Frequency Hop". You will have to look very closely at the rear of the boat at full speed to see if you see ANY high frequency hop.

As an example, on my 20 boat I use 1.3 degrees of angle. That is the perfect angle to help launch and acceleration WITHOUT High Frequency Hop.

Is it the same for all boats...?? NO, it has to do with a lot of variables including strut weight, prop, CG, rear sponson attack angle and probably some more. Maybe dynamic cg too.

So, it is dependent on the specific boat and you can tune it at the pond by looking very closely during full speed pass down the front straightaway.

What kind of boat is it most important on? The more strut weight the more improtant. For example, a heavy tail weight (rear wing boat) 1/8 scale boat it is CRITICAL the angle on the strut. This will be thing that will keep the boat from dropping the rear of the boat in the turns and help it accelerate out of the turns. The heavier the strut weight, the higher the angle you will need on the strut.

Probably more than you wanted, but important enough to put in the archives of IW. This is a KEY COMPONENT of a great running boat of any kind.

Hahaha! Hey Marty, I think you had an itch that needed scratching. LOL. Actually, not enough information, because I'm very curious to what happens with my boat. I had a small battery pack and I changed to a 2500 5 cell 6 volt pack and that's when I noticed that my boat needed that extra degree on the strut. With the small pack, I was at 0 degrees and now I'm at 1. So definitely the weight needed that extra degree and I'm wondering if I should go even more and see where that takes me. My boat is very fast on straightaways... it has problems handling the turns, and I think I just found out what the problem was, thanks to a little angel that PMed me hahaha :lol: To tell me some of the sponson depth measurements, and even though my angles on the digital angle meter were right on the money, the depth on the right sponson was way the hell out of whack (by 1/4" :blink: ) What I did notice was exactly what you said... that my boat picked up speed on the turns, with the angle strut and also on pushing the 1462 full size with my pipe at 9" and it launches very easily and stays on the pipe at any RPM. So keep it coming with all your little secrets! It's never to late to learn.

Thanks

Nick

 

[Speed Jr.]

Some of where you want the strut angle can be linked to the prop that your running also....I noticed that a little strut angle was needed when running a back-cut 1657 and no angle was needed whatsoever with the stock 1657. So the lifting characteristics of the propeller will come in to play with the strut also.....great information Marty!

Jr.

 

[Buckshot]

I'd like to hear how some of you guys are measuring your strut angles.

 

[Ron Zaker Jr]

I'd like to hear how some of you guys are measuring your strut angles.

table,digital smart tool, and /or "string"

 

[Marty Davis]

.100 degree? Or .1 degree? What tool do you use to measure .100 degree?

I agree that .1 degree is important. Isn't .1 degree the same as .100 degree?

 

[Ray Sametz]

I'd like to hear how some of you guys are measuring your strut angles.

Right angle trig, shim height divided by strut length, then use the trig tables.

 

[Marty Davis]

I'd like to hear how some of you guys are measuring your strut angles.

table,digital smart tool, and /or "string"

Why don't you expand on that for everyone?

 

[Ray Sametz]

I'd like to hear how some of you guys are measuring your strut angles.

table,digital smart tool, and /or "string"

I was wondering who was gonna bring up the famous "string"

 

[Nigtmare]

I'd like to hear how some of you guys are measuring your strut angles.

table,digital smart tool, and /or "string"

I was wondering who was gonna bring up the famous "string"

thats old school <_< it dose work but you need to know how dip it has to be according to the front sponsons some say 1/2" some say 3/8" others say 1/4 I think the smart digital meter is the ticket here B)

Nick

 

[Ray Sametz]

Digital levels are a great thing, but theres something Old School called books. John G. Anderson "Techinical Shop Mathematics" think Marty turned me on to that one many years ago.

 

[Ray Sametz]

Example: My 45 shooter strut is 1.815 L, divided by .033 shim up front gives me .0181818. According to Trig table I'm a tick over 1degree-2min.

 

[Andy Brown]

.100 degree? Or .1 degree? What tool do you use to measure .100 degree?

I agree that .1 degree is important. Isn't .1 degree the same as .100 degree?

I just had to asked because Steve said there was no typo. To write the extra zeros is Significant.

Writing .100 degree is to indicated the measurement was measured with an instrument that is accurate .001 or that the measurement is Expected to be within that tolerance. If .1 is written then it is expected that the tool used was only accurate to .1. It would be out of conformation to write .10 or .100 If the tool was only good to .1

I think most Smart levels are good to .1 degree.

It's simply the proper science of significant figures.

 

[Andy Brown]

Example: My 45 shooter strut is 1.815 L, divided by .033 shim up front gives me .0181818. According to Trig table I'm a tick over 1degree-2min.

Ray,

I'm just pointing something out here as per my last post.....not picking on you.

Significant figures are important. You measured and wrote 1.815 and .033. By the proper usage of significant figures you can only write your solution as .018. To add the additional digits you would have had to have more accuracy in both of your measurements.

I kinda point this out, because the last time I looked at the upper limit for IMPBA "F" class, the max engine displacement was carried out to four decimal places. The problem with doing that in the rule book is that no body at an event has the tools that could measure an engine to that tolerance.

An engine could be showing to be .001" too big by the CD's measuring tools, but if the engine was actually measured with a more accurate tool that was good to .0001" then the engine may in fact be legal. In the past I had proposed to simply trim the numbers in the rule book to 2 significant digits.

Such as .21, .46, .67 and so on. This would allow our standard toolbox measuring devices to be totally valid.

P.S. I measure my struts the same way you do Ray...and simply do the math.