Astec Hobbies Micro F1 Tunnel Hull FE

[FECrazy]

Hi from a newbie who's just built his first Fast Electric in 20 years.

Background : I built and ran K&B 3.5 Outboards when they first came out, on a Dumas Hotshot, then a Hotshot 21. While wickedly fast, they required a small entourage of support equipment and were tempermental to say the least.

Fast Electrics : So fast forward to about 1990 and I wanted an electric boat and got the Graupner Key West. Hopped it up with two 7.2V NiCd packs and had a really good time.

Now : Have some money, don't have a lot of time to tinker, but was inspired by this forum and others to get back into RC, seriously. My true RC love is boats, so naturally I researched F1 Tunnel Hulls.

Why This One? : I have a 200 Feet by 90 Foot Man Made Pond enroute to my work. It's an ideal location for running small RC boats, but not something big. So I looked for something more appropriately sized for this Pond.

The Hull : Astec Hobbies F1 Tunnel Hull in ABS Plastic (Cost about $35 Canadian)

Motor : E-Bay Vendor "Head of River - RC Specialist" 2040 Brushless Inrunner, 2960 kv, Water Cooled Motor & Mount & Collett Sourced here

Hardware : OSE Micro Strut, 52 mm Micro Rudder (OSE Stocks this)
0.098 Octura Flex Cable to a 3/16" Drive Shaft with a 30 mm OSE Carbon Filled Plastic Prop

Electronics : HobbyKing 2.4 GHz 2 Channel Wheel Radio, with Turnigy Mini Servo and Turnigy 35A Water Cooled & Water Proof Brushless Speed Control

Batteries : Turnigy Nano LiPo 2S 25C 1300 mah

Cost of Project : $125 Canadian (Roughly $118 US)

Video of the First Run :

http://www.youtube.com/watch?v=R6RL0oE2wEU

Pictures :
1. Note the size, 14" by 6.75"
2. The business end, 30 mm Prop, two ABS Edges glued on the Inside of the Sponsons, since ABS doesn't produce sharp edges
3. Side
4. Bottom
5. Other Side

Questions :
-Estimates of how fast this boat is going from the video?
-Any suggestions to make it run better?
-The current strut angle is 0 degrees, the centerline of the prop is 2 mm below the rear edge of the hull
-I note the hull is "tail heavy" right now and I'm moving stuff forward aiming for a 30 % from the rear edge Center of Gravity

Thanks for everyone's advice !

[NativePaul]

Try it with he bottom of the strut 3mm above the bottom of the sponsons which should get that prop running in surface drive mode and pick up some RPMs and speed, and it looks like your doing the right thing moving stuff forwards, that will help keep the prop on the surface too.

[FECrazy]

Thanks NativePaul

I already have it running close to 95%, now it's the fun part with strut angle and trying different sized props.

I just dropped a 4800KV 2030 Motor in, but I don't know if the fibre reinforced prop is going to just explode...

At least I'm only on 2S LiPos

[Brushless55]

That thing looks sweet

[wparsons]

I would glue an ABS ride pad to the bottom of the sponsons, not the inside edge like you have. I would also raise the prop so that the bottom of the strut is at the same level as the bottom of the sponsons, or a mm or two higher.

I think you're on the right track with moving weight forward, and remember that tunnels tend to porpoise quite badly at partial throttle, so you'll have to keep it at higher power to get it running smooth.

Where did you get the hull, looks like a fun boat to build!

[F1 madness]

wparsons this is the one - http://www.astecmodels.co.uk/catalog...roducts_id=201

[FECrazy]

Thanks for pointing wparsons in the right direction F1 Madness !

I love your user name !

Alan at Astec was fantastic.
I originally ordered one hull, and the posties decided to pancake it, so I needed a replacement.

Alan sent me one at no cost, but the boat was so nice I ordered another so I can race !

It's a really well engineered and moulded boat, considering it's ABS, not that there is anything wrong with that.

The only thing I changed was the cowl cut lines, since leaving more material on the actual hull made it a lot stiffer.

I can tell you I have as much fun as my 3.5 K&B outboards without the hassles!

[FECrazy]

wparsons

Ride Pad

Can you give me your thoughts on size of the pad relative to sponson?

Should it end at the end of the sponson, or extend a slight bit?

Pictures would be appreciated.

Thanks,

FE Crazy

[wparsons]

I've been seeing more and more boats that have the ride pad extend a slight bit beyond the edges of sponsons, the theory is that it helps the water break off cleanly and ride smoother and faster. I would only have it overhang about 1mm though, not a huge amount.

No pictures on a tunnel hull unfortunately, but I can find this:

http://static.rcgroups.com/forums/attachments/2/8/9/6/9/5/a3426568-21-IMG_7113.jpg?d=1282334172

and

http://static.rcgroups.com/forums/attachments/3/0/8/4/1/a3430184-187-JAE12%20003.jpg?d=1282493128

You might have to be logged in to see those though? If that's the case and you don't have an account, let me know and I'll save/re-host them.

[FECrazy]

Thanks wparsons

I like what the slim turn fins do for the hull, so maybe I'll incorporate both ideas and see what happens !

[FECrazy]

Motor Fire : I might need on board fire extinguishers !!!

Sometimes you get what you pay for, sometimes you almost burn your boat to the waterline !

This is what happened to a HobbyWing motor bought from Hobby Partz in quest of more speed.

I wonder if anyone builds a micro sized RC boat fire supression system?

I'm just glad my LiPo's and ESC didn't explode...