Arrow IV
05-12-2010, 04:18 PM
#1
Arrow IV
I'm putting this one here because there's a wonderful seaplane design that's getting kind of ignored due to some unknown problems on some of the earlier builds. I'll post it also on the speed freak forum, as with a very light 40 such as a Jett, this thing could really haul butt.
Laddie Mikulasko's Arrow is not only beautiful, but it's a marvelous ROW bird that tolerates a lot more wind and wave action than the average design.
The build thread for my fourth one starts here, near the bottom of the page:
http://www.rcuniverse.com/forum/m_72...tm.htm#9354248
The plans are available from RCM, at this URL:
http://www.rcmplans.com/index.php?ma...oducts_id=2148 $17.75 plus shipping, and it typically costs less than 10 bucks to get them shipped rolled up in a tube.
First time "builders-from-plans" and people without much plans experience should dive right in. It's a very simple design and it builds quickly. I started mine on Dec 23 last year, and it was essentially RTF by the end of February. We were gone on vacation for two weeks during that time, and I goofed off a lot during the build. If someone was to press on regardless during the build, I'm sure one could be knocked out in well under a month of evenings.
I'll summarize the changes necessary to the original design here, so anyone contemplating one will know the essentials going in:
1. Five degrees downthrust. Essential to get rid of the nasty throttle/pitch down coupling that comes from a high mounted, rear engine.
2. The lightest possible 40 class engine mounted as far forward as possible on a long plastic engine mount. (Mine is a 46AX) I recommend something that can do well with a 10" prop, then, when installing the engine pod, have the engine in place so the prop tips can be spaced no more than 1/4" above the aft deck. Again, this helps get rid of the throttle/pitch coupling.
3. Use an 8 oz tank and the lightest muffler (mine is a Macs) you can find. These plus the light engine mounted far forward will alleviate most of the problems with this design building out "tail heavy".
4. Use Sullivan's heaviest push cable for the throttle, and Great Planes metal wire pushrods for the flight controls (2-56).
5. Use Four Futaba S-3305 servos or the equivalent, mounted in the forward location shown on the plans. The controls surfaces are big and there's a fair amount of drag in the long pushrods. The 3305s in this application really make a difference- everything centers up really nicely.
6. A Hydrimax 2000 4.6V NiMh pack in the extreme forward end of the nose, under a small hatch, along with an ounce or two of lead will balance the bird at 15-5/8" forward of the elevon hinge line. This is when combined with an ounce of lead on the extreme left wingtip to get it to balance L-R. (You may not need as much)
7. 1/8 light ply bottom forward of the step, and 1/8 light ply top decking under the engine pylon instead of 1/8 balsa.
8. Support strips of 1/4 square balsa over the butt edges of all balsa sheeting top and bottom to prevent caving in.
9. Plastic film covering everywhere for weight savings, and get the edges really right to keep water out. If you need some tips on how to do this, PM me.
Doing the above resulted in an all up weight without fuel of just over 5.5 pounds. I can't begin to describe how easy this airplane is to fly and how much fun it is. It really draws a crowd down at the lake.
Laddie Mikulasko's Arrow is not only beautiful, but it's a marvelous ROW bird that tolerates a lot more wind and wave action than the average design.
The build thread for my fourth one starts here, near the bottom of the page:
http://www.rcuniverse.com/forum/m_72...tm.htm#9354248
The plans are available from RCM, at this URL:
http://www.rcmplans.com/index.php?ma...oducts_id=2148 $17.75 plus shipping, and it typically costs less than 10 bucks to get them shipped rolled up in a tube.
First time "builders-from-plans" and people without much plans experience should dive right in. It's a very simple design and it builds quickly. I started mine on Dec 23 last year, and it was essentially RTF by the end of February. We were gone on vacation for two weeks during that time, and I goofed off a lot during the build. If someone was to press on regardless during the build, I'm sure one could be knocked out in well under a month of evenings.
I'll summarize the changes necessary to the original design here, so anyone contemplating one will know the essentials going in:
1. Five degrees downthrust. Essential to get rid of the nasty throttle/pitch down coupling that comes from a high mounted, rear engine.
2. The lightest possible 40 class engine mounted as far forward as possible on a long plastic engine mount. (Mine is a 46AX) I recommend something that can do well with a 10" prop, then, when installing the engine pod, have the engine in place so the prop tips can be spaced no more than 1/4" above the aft deck. Again, this helps get rid of the throttle/pitch coupling.
3. Use an 8 oz tank and the lightest muffler (mine is a Macs) you can find. These plus the light engine mounted far forward will alleviate most of the problems with this design building out "tail heavy".
4. Use Sullivan's heaviest push cable for the throttle, and Great Planes metal wire pushrods for the flight controls (2-56).
5. Use Four Futaba S-3305 servos or the equivalent, mounted in the forward location shown on the plans. The controls surfaces are big and there's a fair amount of drag in the long pushrods. The 3305s in this application really make a difference- everything centers up really nicely.
6. A Hydrimax 2000 4.6V NiMh pack in the extreme forward end of the nose, under a small hatch, along with an ounce or two of lead will balance the bird at 15-5/8" forward of the elevon hinge line. This is when combined with an ounce of lead on the extreme left wingtip to get it to balance L-R. (You may not need as much)
7. 1/8 light ply bottom forward of the step, and 1/8 light ply top decking under the engine pylon instead of 1/8 balsa.
8. Support strips of 1/4 square balsa over the butt edges of all balsa sheeting top and bottom to prevent caving in.
9. Plastic film covering everywhere for weight savings, and get the edges really right to keep water out. If you need some tips on how to do this, PM me.
Doing the above resulted in an all up weight without fuel of just over 5.5 pounds. I can't begin to describe how easy this airplane is to fly and how much fun it is. It really draws a crowd down at the lake.
05-12-2010, 06:35 PM
#2
RE: Arrow IV
Not really my style, but I always give respect to fellow scratch builders,, wow that engine incidence is awesome
I was just browsing RCM plans yesterday,, there are some great Sea Plane & Flying Boat choices there,
I'm think of this [link=http://www.rcmplans.com/index.php?main_page=product_info&cPath=6&products_id=2108]AICHI M6A1 SEIRAN[/link] enlarged about 125-130% would be great winter project
I was just browsing RCM plans yesterday,, there are some great Sea Plane & Flying Boat choices there,
I'm think of this [link=http://www.rcmplans.com/index.php?main_page=product_info&cPath=6&products_id=2108]AICHI M6A1 SEIRAN[/link] enlarged about 125-130% would be great winter project
