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Old 01-02-2015, 03:29 AM
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Buzzzzz 2 Pulsejet Paper Airplane

Nice way to start 2015, completed Buzzzzz project at 1045pm Alaska time, on 01-01-2015.

400-photos during construction.

Since the first Buzzzz project here at PM.com, redesign, redesign, built a 1/2 size for part fit and then realize no way to make it work. After several drawings, finally hit on a workable design. This thread is how it was made.

Besides Springhill Tag 125# Cardstock, other materials used are in the following list:
1) Metal 22 gauge plate for heat shield
2) 1/4" Thick x 3" Wide wood for Engine Mount, Battery / fuel mounts, electronics, finally to add strength to model and transfer power from engine to structure
3) Fiberglass resin, hardener, fiberglass matt & cloth for wing spars
4) Back of a desk calendar (heavy duty cardstock) for laminations
5) Ceramic Paper refractory for heat insulation between engine mounts and heat shield.

Photo 1 shows misc. items, cardstock patterns for wood metal heat shield, fuel tank.
Buzzzzz 2 Pulsejet Paper Airplane-1.jpg

Photo 2 shows using a fiskars hobby knife to carve wood to pattern shape.
Buzzzzz 2 Pulsejet Paper Airplane-2.jpg

Photo 3 shows completed part before starting on second piece.
Buzzzzz 2 Pulsejet Paper Airplane-3.jpg

Photo 4 shows 2/3 completed wood mount system. Checking for fit. Pulsejet with cardstock heat shield pattern.
Buzzzzz 2 Pulsejet Paper Airplane-4.jpg

Photo 5 shows part location. Battery will lay flat under fuel tank, engine will mount to wood skid by use of screws with a metal heat shield under it. Skid still needs floor added.
Buzzzzz 2 Pulsejet Paper Airplane-5.jpg

Well lots more to follow-got to get some sleep, work tomorrow!

Mike

Last edited by rickstef; 01-03-2015 at 12:36 PM.
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Old 01-02-2015, 08:33 PM
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I'm subscribed...and excited to see this!
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Old 01-02-2015, 08:49 PM
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About 15 years ago I went to a control line model fly-in, there were 2 guys with pulse jet models. They go to start one using a compressed air tank with maybe 30 people standing around watching, well the thing fires for about a second, lets out a huge ROAR, and about 10 people almost run back away. Few seconds later it fires this time for about 3 seconds, lets out an even louder ROAR and the spectator's all run like hell. With just the guys starting it this time it fires, and BOOM it's off and flying about 200mph...One of the coolest thing I ever saw. It ran for about 2 minutes the coasted for about 4 more before it stopped! I'll never forget it............Rich
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Old 01-02-2015, 09:23 PM
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Metal Working, Fiberglass & Fuel System

This post will cover the heat shield, fiberglass spar layout, and fuel system.

The first couple of pulsejets I bought used propane for the fuel. This caused issues here in Alaska, because the pressure drops when propane gets cold. The boiling point for propane is -44 deg F. When it gets cold it doesn't boil fast enough to keep the pressure high enough.

Need a different fuel type. Found a new pulsejet engine that uses regular car gasoline. Biggest issue is finding fuel lines that can handle gas instead of most fuel types used in RC or control line models.

Metal working the 22 gauge metal plate into a heat shield means cutting. Luckily have a hand powered metal "nibbler" that can handle the task. Notice the cardstock pattern with bolt holes. Used the leather hole punch to make nice clean little bolt holes in the card to transfer to the metal. Misc. items in the photo are the 8-oz fuel tank, 11.1 volt 3s lipo battery pack.
Photo 6 shows the nibbler at work, notice how I've got it trained to do everything by itself...
Buzzzzz 2 Pulsejet Paper Airplane-6.jpg

Photo 7 shows clamping the wood "power skid" using 5-minute epoxy.
Buzzzzz 2 Pulsejet Paper Airplane-7.jpg

Photo 8 shows the complete to this point power skid, heat shield (minus a few holes) and the fuel tank and fuel line. Under the fuel tank is where the battery rides. A Velcro strap hold the tank and battery nice and snug (not shown).
Buzzzzz 2 Pulsejet Paper Airplane-8.jpg

Photo 9 shows fiberglass wing-spar lay-up. Notice the cardstock paatern on top of the curing resin/hardener. Used alternating fiberglass mat and cloth for 6-layers. Total thickness when done was right at 3/32".
Buzzzzz 2 Pulsejet Paper Airplane-9.jpg

Photo 10 shows what might save someone's cutting mat. First choice for wing-spar material was some expensive carbon fiber/Kevlar cloth mix. Just thought it would be a no-brainer to cut to size using my rotary cutter on top of my $70 Alvin matt. Almost impossible to cut! after going back and forth with great pressure applied it finally cut through, the end result is many cut marks on my mat and the weave got stuck into the matt. Un-happy is an understatement! Was able to pull the weave out using my needle nose pliers, but matt still has those nasty cut grooves now.
Buzzzzz 2 Pulsejet Paper Airplane-10.jpg

Some of the issues with trying to use a pulsejet and paper are as follows:
Rudder (s) need to be located far, far away
As much of the model parts/pieces away from the heat source (pulsejet)
Try to keep the engine as near to the CG (Center of Gravity or balance location)

After trying a couple of different designs decided to do a flying wing with the rudders located on the wingtips. About as far away from the engine as possible.

For controls decided to "mix" the aileron and elevator into a single control surface. This meant buying a different Radio Transmitter and Receiver.

More to follow!

Mike
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Old 01-02-2015, 09:29 PM
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Hi Dave & Rich,

Hope I don't disappoint Dave!

Rich traded back in 2002 for a Suzuki Edwards F94 C Starfire control line and Tiger Jet pulsejet. 1950's vintage. Ended up selling them on ebay to pay an attorney for a divorce. Have some photos if you're interested in seeing them. Model said it was the record holder for control line models at 215 mph.. Was to pretty to build and fly! Should have though.

That model is what got me thinking about building a paper model for pulsejet!

Mike
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Old 01-02-2015, 09:44 PM
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The first ever aircraft I can remember seeing in flight was powered by a pulse jet.
That one flew past, but a couple of weeks later one of it's mates didn't.
Luft 44 could be real messy at times. Not sure I like pulse jets.

But your engineering processes are well worth watching.

Might canard be better than tailless for flight stability?
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Old 01-02-2015, 11:21 PM
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Wing Construction

Ok, spars are cured. How to shape?

Visited many boat building sites looking for answer. Everything from carbide blade skil saws to diamond grit blades for ceramic tiles. One guy said to use a hacksaw.

Everyone said messy, messy and get ready to itch and massive clean-up issues.

Where I work we sell tyvek suits and respirators, duct tape and first aid kits. Ok, got my choice of PPE (personal protective equipment).

My saw of choice is a little Milwaukee variable speed sabre saw. Looked for and found a diamond grit blade. Thinking that this type of saw wouldn't create such a big dust cloud of fiberglass dust.

Smart choice! Started with the speed at the low end to test if it would work. It did! Slowly cranked the speed up and found the faster it went the easier it was to control and easier cutting. Went overboard and maxed it out, big mistake...Like a hot butter knife going through hot butter, no control and it flat tore the fiberglass up.

Slowed it down to about 2/3 max speed and had the spars cut in about 15-minutes. No major dust cloud, no big mess, and goggles and dust mask where the only PPE needed. Oh, and cut resistant gloves!

On the cut resistant gloves. I've stopped buying the thermal type and utility gloves that have great grip (plastic dipped on a knit glove). The cut gloves come in many different weights and dexterity. I use them for everything now. In other words, I don't have scratches or cut marks on my hands anymore. My favorite ones cost $6.50 a pair and are made of dynema, light weight and dexterity is great. last a long time and the protection is fantastic! Home repair, auto repair, fish cleaning, to model building!

Ok, back to the model...

Photo 11 shows wing spar test fit, before sanding and smoothing of spars.
Buzzzzz 2 Pulsejet Paper Airplane-11.jpg

Photo 12 shows ribs, spars and engine mount.
Buzzzzz 2 Pulsejet Paper Airplane-12.jpg

Photo 13 shows right wing rib test fit. Ribs are a single layer of Springhill Tag 125lb with a laminate using heavy card that is on the back of notebooks or legal pads (yellow paper).
Buzzzzz 2 Pulsejet Paper Airplane-13.jpg

Photo 14 shows a close up. Notice how spars are a little wavy, cleaned up nicely with a diamond grit file.
Buzzzzz 2 Pulsejet Paper Airplane-14.jpg

Photo 15 shows ribs in place and shape of wing.
Buzzzzz 2 Pulsejet Paper Airplane-15.jpg

Anyone guess yet at the paint scheme I'm going to use?

More to follow!

Mike
Buzzzzz 2 Pulsejet Paper Airplane-13.jpg
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Old 01-02-2015, 11:41 PM
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Quote:
Originally Posted by maurice View Post
The first ever aircraft I can remember seeing in flight was powered by a pulse jet.
That one flew past, but a couple of weeks later one of it's mates didn't.
Luft 44 could be real messy at times. Not sure I like pulse jets.

But your engineering processes are well worth watching.

Might canard be better than tailless for flight stability?
hi Maurice,

After several tries at this, biggest problem was getting to complicated and heavy, real heavy. Wanted something simple to do and light weight.

As it is right now stability could be an issue, only have a Static Margin of .68". This is an indication of stability. It is the distance from the CG location to the Aerodynamic Center of the model.

The aerodynamic center is a measurement of the lifting surfaces and their related "aerodynamic center". It is a complicated process. Anything forward of the CG moves the Aerodynamic Center forward.

A canard moves it forward big time. You need to have the Aerodynamic Center (AC) behind the CG location for a stable aircraft. As it is now the AC is located .68" behind the CG. I would be happier if it was an inch!

To install a canard would involve a much more complicated "control" design. With a flying wing, Elevons can work as the sole control surfaces.

Elevons control Roll and pitch, simple enough to use two servos for everything.

Rudders will be fixed.

Mike
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Old 01-02-2015, 11:59 PM
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mbauer mbauer is offline
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Test Fitting/Verify Porportions of Control Surfaces

Time to test fit and verify servo cable lengths, general layout of control surfaces.

Not much going on here. Just basic layout and verify everything will fit, before actual installations.

Photo 16 shows where the servos are going. Notice using a Y-cord to connect the servos. Actual finished model will use Transmitter mixing to work the Elevons (Y-cord not used).
Buzzzzz 2 Pulsejet Paper Airplane-16.jpg

Photo 17 shows the same from a different angle. Radio Receiver will be attached to the front piece of wood using Velcro!
Buzzzzz 2 Pulsejet Paper Airplane-17.jpg

Photo 18 shows Rudder and Elevon locations.
Buzzzzz 2 Pulsejet Paper Airplane-18.jpg

Photo 19 gives big hint on what the paint scheme is going to look like. Fuselage pieces that hide the fuel tank and electronics. Fuselage doesn't have to carry much flight load, other than its own weight. All the heavy stuff is located inside the wood skid.
Buzzzzz 2 Pulsejet Paper Airplane-19.jpg

photo 20 shows a wing skin to give a better idea of the paint scheme...
Buzzzzz 2 Pulsejet Paper Airplane-20.jpg

Next post will show wood shaping, servo mounts etc...

Mike
Buzzzzz 2 Pulsejet Paper Airplane-19.jpg
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Old 01-03-2015, 12:47 AM
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mbauer mbauer is offline
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Wood Work

Ok time to angle the spar openings so that the spars angle back instead of sticking out at 90 degrees.

To modify the openings will be using a Riffler File set that has 5 files with a double cut cutting surface. They are bigger than needle files and have a bend approx. 1/3 the distance from the end. Great for getting into hard to reach areas.

Photo 21 shows the "flat" riffler angling the main spar opening.
Buzzzzz 2 Pulsejet Paper Airplane-21.jpg

Photo 22 shows the riffler file bend. notice how great it is to use for these angles?
Buzzzzz 2 Pulsejet Paper Airplane-22.jpg

Yes, they can also work as a pry bar. Notice how thin the wood is near the end of the openings. Real easy to apply the wrong "prying" pressure and break the wood. Yep, you guessed it, broke one of the back spar openings...

Photo 23 shows my little finger twist drill. Want one? Can be purchased for $12 at your local Airgas USA, LLC welding supply. Come with the smallest drill bit sizes in the handle. Used to clean acetylene cutting tip openings. It is a Radnor part number. If you buy one, use caution when opening the drill bit compartment, the smallers sizes are smaller than a sewing straight pin, real easy to drop and loose...Till you're barefoot...
Buzzzzz 2 Pulsejet Paper Airplane-23.jpg

Photo 24 shows first servo mounted.
Buzzzzz 2 Pulsejet Paper Airplane-24.jpg

More to follow..

Mike
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