Thread Tools
Jun 23, 2019, 02:22 PM
Registered User
Steve Merrill's Avatar
Thread OP
Build Log

Hammer 20


I was inspired by another thread to start my build of another classic Dick Sarpolus airplane, the Hammer!

Mine will be e-powered and will incorporate a large battery hatch on top. I think with a E-flite Power 25 and a 4 cell 4000 mah lipo, and a Castle 50 amp ESC I should have plenty of performance. I will try to build as light as possible by incorporating some “holes” here and there.

First step is to transfer the plan templates to balsa. I use a light plastic material called See-temp to make patterns that I then trace around on the balsa. Always making the parts slightly larger, then using a sanding disk to match the plans.

This plane has a symmetrical airfoil and each rib is different so a little more work, but easy. I’m too cheap to buy laser cut parts, also don’t have the patience to wait

This may be a slow build, as it’s flying season ya know
Sign up now
to remove ads between posts
Jun 23, 2019, 07:53 PM
Registered User
slow_flier's Avatar
Great minds must think alike. That's the same combination I've been considering.

The plans on outerzone http://outerzone.co.uk/plan_details.asp?ID=10680 show two fuselage constructions. I was thinking that the top hatch on the rear exhaust/tuned pipe version would make a great battery hatch and the pipe exhaust an outlet for the motor, battery and ESC hot air.

Just thinking

Tom K
Jun 24, 2019, 05:39 AM
Registered User
Steve Merrill's Avatar
Thread OP
Thanks for posting the link to the plans. I was wondering why the wing was shown in two locations, now I know itís for adding more room when using an internal pipe. Perfect for e power, as it will allow plenty of room fo a large 4 cell lipo.
Jun 24, 2019, 02:23 PM
Registered User
hi Steve, Tom et others,

Probably of interest is this fairly long thread discussion of the Hammer series that was in the "classic pattern" subcategory around July, 2015
https://www.rcgroups.com/forums/show...ammer-40-plans

A several highlights:

-over the Hammer series, the wing location varied from slightly under the engine thrust line , to inline to slightly above thrust line. The Cox .049 powered Tack Hammer - plans/article on Outerzone by searching "tack hammer"... this design variant was by Leon Schnitzspahn and was published in Flying Models, where Dick Sarpolus first published the initial Hammer (20) design

-the thread contains a link to the full size plans for the Hammer 40 (post #9) which had options for a slightly below thrustline one piece wing location and a slightly above thrustline plug wings location...


-the initial Hammer 20 design had 1.25" dihedral under each wing tip while the Hammer 40, also published by Dick Sarpolus, had less: .75" under each wing tip. I personally would build the wing with the top side flat for a bit of dihedral.


Michael in Ontario, Canada
Last edited by 2michaely; Jun 24, 2019 at 02:32 PM.
Jun 24, 2019, 03:37 PM
Registered User
slow_flier's Avatar
Hi Michael-

I looked the thread over and do like your idea of building it flat across the top, but would probably build it per plans. I'm getting older and like a little more stability designed into my airplanes. As for Steve, he may like the flatter wing and the improvement in aerobatic performance it would provide.

Tom K
Jun 24, 2019, 04:56 PM
Registered User
Steve Merrill's Avatar
Thread OP
Thanks guys. My plans call for just over an inch of dihedral on each panel. I'm a ways away from making that call, but I'll probably go by the plans.
Jun 24, 2019, 07:13 PM
Registered User
I would not leave out the dihedral on a low winged aircraft. You are likely to have adverse roll when using the rudder. This means that right rudder makes the aircraft roll left. For an acrobatic model, the right amount of dihedral decouples the roll from rudder input. To much causes proverse roll which is actually how most full scale aircraft are designed to give flight control redundancy.
Jun 30, 2019, 03:16 PM
Registered User
Steve Merrill's Avatar
Thread OP
Rainy, hot and humid Sunday today. Spent a couple hours in the workshop. I cut out more parts. Decided on the lower wing fuse version, which will give me more space in the fuse for large lipo battery. Itís hard to tell the difference looking at the plans, but when you cut out a part, then compare it to,the other fuse, the difference is apparent
Aug 11, 2019, 02:01 PM
Registered User
Steve Merrill's Avatar
Thread OP
Finally got my fuse jig put together and it came out great! I picked up more balsa at the hobby shop and cut out the ribs. Getting close to having a complete kit. Will start building her very soon
Aug 11, 2019, 03:34 PM
Registered User
Quote:
Originally Posted by Steve Merrill
Finally got my fuse jig put together and it came out great! I picked up more balsa at the hobby shop and cut out the ribs. Getting close to having a complete kit. Will start building her very soon
Congrats on making the fuselage jig.... I'm sure you will find it a big aid in constructing straight fuselage.
If that jig is 48 inches long and longitudinal spacing is one inch, and you have drilled for five locations, you have about another 250 holes to drill, leaving out the fuselage centerline holes in your diagram....smiley

Michael in Ontario, Canada
Aug 11, 2019, 04:37 PM
Registered User
Steve Merrill's Avatar
Thread OP
Yes it is 48Ē long, so plenty of versatility down the road

Here are pics of the actual glueing, and the end result, Iím satisfied
Aug 12, 2019, 12:00 PM
Pro Hoarder
turbonut's Avatar
Nice I like the fuse jig..Looks a bit like the one have..It works great for building a straight fuselage
Latest blog entry: In flight
Aug 14, 2019, 03:43 PM
And You're Not
Quote:
Originally Posted by Highplanes
I would not leave out the dihedral on a low winged aircraft. You are likely to have adverse roll when using the rudder. This means that right rudder makes the aircraft roll left. For an acrobatic model, the right amount of dihedral decouples the roll from rudder input. To much causes proverse roll which is actually how most full scale aircraft are designed to give flight control redundancy.
I've had two Hammer 20s, both from Champion kits. I bet I've mentioned it in one of the other threads, but they are one of the absolutely lowest roll coupling planes I've flown. Fly along straight and level, feed in rudder and do a flat turn with no aileron input.

I have another kit stashed back, they are a great little plane.

Aug 17, 2019, 03:38 PM
Wanted for breaking Ohm's Law
Dennis Sumner's Avatar
Steve,

I found the thread and will follow along. I remember seeing those kits, it sure looks like it will make a great electric conversion!

I may have to download the plan and have it printed.....

Denny
Latest blog entry: RC Throw Gauge
Aug 18, 2019, 08:37 PM
Registered User
Steve Merrill's Avatar
Thread OP
I completed the motor mount, and incorporated the nose gear bearing to the firewall. Had to add some spacers and then modify them with my Dremel, to clear the blind nuts


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Hammer .20 toad007 Classic Pattern Flying 35 Nov 24, 2017 06:29 PM
Discussion The Hammer .60 size OR Hammer .20 bacplus Classic Pattern Flying 11 Jun 23, 2016 06:05 PM
Alert End of Year Sale, IQ Hammer Turbines - Vogelsang Aeroscale MattyMatt2 Jet Turbines 0 Nov 11, 2015 11:21 PM
Video hammer V3 mini 5" Sixchannel Multirotor Drone Talk 0 Sep 13, 2015 11:41 AM
Discussion Davey Systems Hammers (20 & 40) HHK Sport Planes 9 Jul 27, 2009 09:44 PM