sahartman21

Awhile back I purchased a Sam-Rai wood Q-500 racer kit. I'm now in the building mode so let's get started.

The kit is available at the following site:

http://www.sam-rairacing.com/

It comes with:

1) Plans
2) Sheeted foam wing - The sheeted cores weigh 10.25 ounces. The airfoil is not a 66012 airfoil. It is thicker on the back side of the airfoil than the 66012. Sam indicated that this airfoil is faster than the 66012 airfoil.
3) Parts for a wood fuselage

sahartman21

The fuselage doublers were glued to the side using wood glue.

The tail surfaces were done similarly.

The wing tips are made from 2 smaller blocks that are glued together.

A vacuum bag was made from pieces of 4 mil thick plastic tarp. They were sealed together with latex caulking.

The bag was closed and about 6" of vacuum was pulled by the pump.

sahartman21

After the doublers are dry you can build a fuselage.

I laid the parts on the workbench to see what was included. The picture (without glues) shows the fuselage parts.

I plan on gluing the body together with "Gorilla" glue, epoxy, and CA.

sahartman21

The provided servo tray is set up for two tail surface servos, but does not include the throttle servo.

I am familiar with a three servo installation, so I cut out my own tray.

sahartman21

I dampened the surface per the instructions on the "Gorilla" glue. A damp towel was rubbed over the future glue joint areas.

sahartman21

The fuselage was trial fitted before applying the glue. Some minor fitting was required.

sahartman21

"Gorilla" glue was applied to the formers and tail block.

I held off gluing the firewall until after the other formers dried in place.

sahartman21

I glued the firewall in place with 30 minute epoxy.

A triangle was used to align the firewall.

Verify that it is true based upon the lines on the paper.

sahartman21

The top and bottom 1/8" thick balsa sheeting was attached with "Gorilla" glue.

Masking tape temporarily holds the sheeting in place until the glue dries.

sahartman21

The tape was removed and the edges were sanded square with a sanding block.

sahartman21

The stinger (tail end) was shaped with a razor saw and sanding block.

sahartman21

Here are a few pictures comparing the Sam-Rai fuselage with the ViperDog fuselage.

The Sam-Rai has a shorter nose and tail moment (from wing to tail surface) than the ViperDog.

sahartman21

I checked the fit for the wing to the saddle.

The incidence was off and was addressed by lowering the high areas of the wing saddle.

This should be close before gluing the wing mounts in place.

sahartman21

The wing hold downs were glued in place with 30-minute epoxy.

I turned the fuselage over to allow the epoxy to run back in the glue joint.

sahartman21

The wood Sam-Rai was designed around a relatively heavy Thunder Tiger Pro 40 (TT40).

I am planning to install a Jett 426 engine that is more than 2 ounces lighter than the TT40.

Another firewall was added to increased the length of the nose. This should help address the change in weight from the engines.

jaka

Hi!
426?? I know 428 and 424...But what is a 426 engine?

[email protected]

whats the weight of a TT40? THnz

sahartman21

Here's the weight of the TT40 vs the 426 Jett with venturi:

1) The TT40 with back-plate mount, prop, and spinner nut weighs 19.5 ounces.
2) The Jett (venturi instead of carburetor) with back-plate mount, prop, and spinner nut weighs 17.2 ounces. This also requires a remote needle valve that weighs 0.4 ounces.
The 426 engine is a very forgiving racing engine that is used for 426 class racing. This class was very popular at this year's NATS.

[email protected]

interesting information- never knew what a TT40/46 actually weighed with a b/plate mount- thanks, wish you well with your project. THnz

sahartman21

Tape the back-plate motor mount to the firewall to hold it in place.

Drill the holes to fit the mount.

Then drill holes big enough for the blind nuts.

Pull the nuts into the firewall with the bolts.

I then switched to a shorter bolt. Add a drop of oil to the threads to keep glue from sticking.

sahartman21

Dab some Skin It epoxy around the firewall, landing gear block, and wing mount blocks.

Sprinkle the cut fiberglass over areas and add epoxy and fiberglass as needed.

Some Skin It was spread over the inner fuselage to seal the wood.

Conrod

So how are you Guy's holding your TT 46 motors on your Quickie planes?

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with a cast aluminium xcantilevered mount............alternative to that was a carbon fibre plate about 10 nmm thick cast between two sheets of glass TH

sahartman21

The top of the fuselage is glued on with epoxy.

I taped parts in place until the glue dried.

After the glue dries the fuselage was rough shaped with a sanding block.

sahartman21

The tail surface was shaped with a pocket knife and sanding block.