Blackbird 21 build thread

[Marty Davis]

Fellas,
If you a deeper strut yes it will lift the transom higher on the boat,but it

will also increase the propeller efficency. The goal is to not rob HP to

get the boat to ride light on the water, correct? If you raise the front angle

of attack more and the back end levels this out with a deeper propeller

setting you will be flying pretty neutral on the water. This is just a different

way to achieve a good fast heat racing boat. There are a lot of different ways

to achieve this. One wise boater told me to run as much: angle,timing,and nitro

% that you can get away with. If 3.2 degrees works for you run it. I doubt you

will ever run 75 to 80 MPH that way though.

Have Fun Testing Fellas,

Mark Sholund

Mark:

I agree with everything you said except the last dig.

FYI, at the Internats several years ago, I ran 86mph with my heat race .21 boat in Trophy Trials, so you are incorrect with this statement. Angles on the sponsons were exactly 3.0 and 3.2.

There ARE many ways to get there though, you are correct about that.

Marty Davis

Mark,

I'm not sure, but I think John Brown still holds the IMPBA 1/3 mile Oval record. Before setting that record John made some passes through the SAW traps and was running about 83 mph.

That boat set up had 3.2 degrees or less.

Marty, It's been a while since I've attended the IMPBA Internats. Which Nats did you run 86 mph at?

Andy:

Sarasota, but as you remember Stevens had the course so screwed up that nobody got correct speed. I based my speed on the testing that I did before I left. The boat won both SAW and Timed Oval and some other guy won US#1 since I had a launch problem in one heat. Can't remember exactly who that other guy was Maybe it was John Brown or somebody like that.

AND, the .21 oval record is an amazing record that probably won't be broken for a while.

Marty Davis

Marty,

I'm getting old and I guess my memory fails me sometimes, but I didn't think you got a time in SAW. I seem to recall that your boat died on the first launch attempt. It was retrieved and Mark Grannis gave it another all out super launch and it died again.

Maybe I've forgotten. Do you remember what kind of speed you ran on John Stevens' messed up course?

Andy:

Yes, I won both SAW and Oval in 20 class. Not sure what the speed said on that course, but it was much above 2nd. I had made pass after pass at 85-86 and it was probably one or the other.

The launch was in heat racing.

Marty

 

[Don Ferrette]

Boy this thread sure has gotten sidetracked ............... :huh:

 

[shoboat]

Andy & Marty,

I may take a shot at the 21 oval record this Fall in Flint,MI. My 21 Hydro is getting

around the course quite well right now. You guys are also part of the few that are

capable to run those speeds with a 21 Hydro with low sponson angles. I think our

future 21 Hydros will be able to run 80 MPH in heat race trim. Mark & Mike have

went 111 MPH & 103 MPH with their 21 S.A.W. set ups, so it is going to be possible

with the 21 engine technology that is coming in the next five years. Andy, do you

think your new MAC 21 motors will be capable of 40,000 RPM? We can now pull

a S-15 propeller with good RPM around the whole race course without a problem.

Thanks For Reading,

Mark Sholund

Don,

You are right, I guess we need to start a new 21 Hydro thread. I can tell you that

my heat race boat is somewhat close to a Blackbird 21, at least the tub is.

Anything new on the testing of your boat Don?

 

[shoboat]

Don,

Did you get to test this weekend?

Thanks,

Mark Sholund

 

[Tim Kish]

Mark

I tested the s-15 on my boat today it was very fast but definately not a good prop for heat racing for me , to much pitch made it difficult to drive.

The engine was screaming though and hitting the pipe hard , launched very easy and pulled it hard through the turns.

Nova engine , S pipe @ 2.75"

Boat is set up at just under 3 degrees.

I will say even with the prop I use for heat racing the boat is a handful when it reaches the mid seventies ,can't imagine heat racing at 80 just don't see it.

Nothing better than a screaming 21 Hydro.

Tim K

 

[Don Ferrette]

Don,
Did you get to test this weekend?

Thanks,

Mark Sholund

Hi Mark-

No weather went south so we are going out tomorrow. The 1450 showed up today so I will try it again as well. B)

 

[Don Ferrette]

Mark, got to test the re-worked 1450 today and it was much better. Boat runs smooth and fast, I'm going to use that prop at the race next weekend. I'll keep you posted. B)

 

[shoboat]

Don,

I hated to give you too much cup to start with.

That blade profile either works well or not at all.

With the reduced blade area ratio you can get

away with more cup on the trailing edge.

Glad it works well for you,we have a few others

in the testing stage that are showing some promise

also.

Thanks,

Mark Sholund

 

[Don Ferrette]

Don,
I hated to give you too much cup to start with.

That blade profile either works well or not at all.

With the reduced blade area ratio you can get

away with more cup on the trailing edge.

Glad it works well for you,we have a few others

in the testing stage that are showing some promise

also.

Thanks,

Mark Sholund

It might still need more, I'll let you know how it does at the race next weekend. B)

 

[Rokieboater]

Don,

Does the MAC .21 run better/faster than the 2008 CMB redhead? I have one of each and not sure which to run at this point in a .21SGX. Are you just more comfortable with the MAC or does it perform better at this point?

Any thoughts??

Robert

 

[Don Ferrette]

Don,Does the MAC .21 run better/faster than the 2008 CMB redhead? I have one of each and not sure which to run at this point in a .21SGX. Are you just more comfortable with the MAC or does it perform better at this point?

Any thoughts??

Robert

You have a p/m.

 

[shoboat]

Don,

More is not a problem,try to shorten your pipe more.

It will go faster if you can get to 7 & 1/4", or 7" or less

like I run.

Have Fun Testing,

Mark Sholund

 

[ek kustomz]

finally looked throught the whole thread, BEAUTIFUL boat Don..

Wanna sell it LOL

 

[Don Ferrette]

finally looked throught the whole thread, BEAUTIFUL boat Don..

Wanna sell it LOL

Thanks. Boat is finally struttin' it's stuff, it ran extremely well this past weekend and if the driver would have not tried to skewer a couple buoys making inside passes it would have gotten 1st overall instead of 3rd.

 

[tnrcboatracer]

I know the feeling. "Keeping a tight course" does not mean over the bouys...... :lol: :lol: :lol:

 

[Chris Wood]

finally looked throught the whole thread, BEAUTIFUL boat Don..

Wanna sell it LOL

Thanks. Boat is finally struttin' it's stuff, it ran extremely well this past weekend and if the driver would have not tried to skewer a couple buoys making inside passes it would have gotten 1st overall instead of 3rd.

lol i told you the boat would turn lol...

congrats and glad the boat is running well for you.

keep me posted.

chris