I have never had the courage to do a blog before so here goes. The Speedtwin was developed by a chap called Phillips in England but he unfortunately passed away after only one original was completed. A new company called Speedtwin developments have taken on the development and hope to turn it into a profitable venture.
It's twin engined tandem trainer, all terrain aircraft. Meant to be used as a trainer or by law enforcement and for surveillance use. it is very versatile as you can see in the attached video.
I can't get the video to load, will talk to Ben.
I saw the plan in RC Aeromodeller and was very much taken by it. I had a pair of motors and ESC's donated by my ill fated Fokker F27 Friendship. They only had about a minute and a half on them so virtually brand new. I bought a copy of the plan to have one on good quality Paper.
Here are some photos of the real thing.
Great looking plane, Jack! Can't wait to see your progress.
OK here's how I go about working off a plan. I sit down with a fresh cup of tea and I look at the plan for hours to try and fix details in my mind. While I'm doing that I have a pad and a measuring tape beside me and I make a list of all the different woods used and approximately how much of each I will need. I also make a list of hardware and finally check where the battery is going to go if the original plan was an ic. job.
I then make photo copies of each part I will need to cut. I trim them to slightly over size and glue them to the appropriate wood with a glue stick. Just enough to hold it in place while I band saw the parts. If I'm making more that one as in ribs for a straight wing I glue enough pieces of wood to make a block. Again using glue stick. Glue stick is water soluble and washes off easily when done.
I use a small band saw and a bench sander for almost all this work.
nice looking plane!
Jack, you have impeccable taste. This looks like a great pattern ship. We will look forward with great anticipation to your maiden flight - and many more thereafter. I hope I can do some portraits of you and what I know will be a beautiful model. How large will the model be?
Good luck on the project!
Andy
It's 45" Wingspan and 1/7 th. scale.
I like to kit everything before I start to build. I cut the interior of Formers using my band saw. I use a wide blade with 18 TPI. What I do is cut through one side and clean out the interior. Since the kerf is 1/32" I glue a piece of 1/32" ply in the gap and it works very well.
This is a quick way and it avoids all that fret work etc.
Here are the two I cut for this model. The keen eyed will note that I cut the tops rather than the sides. Just being dumb the sides are supported by the glue and are much stronger.
Jack.
Here's a picture of some of the kitted parts. After cutting on the band saw, as close to the line as possible, I finish each piece on the table top belt sander. My stuff is all Canadian Tire or Home Depot, nothing fancy. It does an adequate job for the price.
Jack.
Impressive work!
Jack, have you seen this Speedtwin build thread by Tim Hooper in the UK?
http://www.modelflying.co.uk/forums/postings.asp?th=65621&p=1 (http://www.modelflying.co.uk/forums/postings.asp?th=65621&p=1)
Yes that's what caught my attention. The plan is Tim's.
Jack.
The wing is built in two halves and joined. It's built on a skin of 1/16 th sheets joined. I use masking tape to join the sheets, this acts like a hinge and I fold the sheets back on themselves and use carpenter's glue brushed in the gap. I unfold them and tape the join and weight the whole thing down. The tape keeps the glue in place and there is virtually no clean up.
Here are the three stages and the final picture is the wing waiting for wiring and hardware plus the top sheeting.
That's the sheeted stab and elevator in front.
Jack.
Nice wing.
Suggestion to everyone: take and post smaller images.
Wow, Jack!
Looking good! You'll be ready to test fly by the weekend at that rate.
And it's great to see another build thread rolling along.
Robert
Jack,
Thanks for posting this build and taking the time to explain to build newbies how you get from A to B. I'm grateful and impressed. You mention a small bandsaw as a useful workshop tool and then proceed to show some formers with pretty straight edges...does the bandsaw cut this straight or is the sander doing the straightening? I have a belt sander and a scroll saw but trying to cut straight lines with the scroll saw has so far been a nothing but a joke.
Your thread has inspired me to get back in the workshop...I've got one scratch build that's been in process for nearly two years and isn't much farther than your wing!
Hi Bill, thank you for your comments. I have an old Ryoby 9" band saw I bought in Home Depot. I paid about $110.00 and they are about $150.00 now. I cut free hand and I have been doing it a long time so I'm comfortable with my fingers near the blade. I just sight along the line and move the stock very slowly, nothing forced. I can usually cut less than a 1/32" from the line. The inside cuts are basically as is. You all know how my hands shake. I have a hereditary condition called essential or elemental tremors. If I can cut this straight then there is no excuse for you guys. The trick is to focus on the blade and have absolutely no distraction and when the cut is made move your hands away and switch off. Do not move until the blade has stopped. Even at slow speed it will give you a nasty tear.
The fuselage is starting to come together. I will have to step away as I have promised to start tidying up tomorrow. that will take me to Friday and the AGM so it will be the weekend before I get going again.
Jack.
Michael I forgot to re-size the shots. Won't happen again i hope.
Jack.
Nice work. It's a lot of cutting to come up with those assembled parts but your producing a beauty. Can't wait to see it come together.
Quote from: Michael on December 04, 2012, 10:16:59 AM
Nice wing.
Suggestion to everyone: take and post smaller images.
FWIW, here is what Michael means. Same image as one of Jack's but ~50 K instead of 2400K
Michael just doesn't want to wait an extra 3 seconds for the pictures to load. He has building to do!
Here's another tip from the school of hard knocks. There is one advantage to aliphatic glues that is not generally promoted. That is the ability to undo a joint without damage. Say for instance you were scratch building a twin and despite much measuring and checking you discover that one fire wall is not in line with the other. If you used carpenter's glue and just covered it with a soaking piece of towel for a couple of hours you could just ease the joints apart with an Exacto knife. No damage at all. Much more difficult if it had been CA'ed or epoxied.
I have been trying Gorilla Glue's new white wood glue and it is very good. Extremely tacky and sets up in half the time.
Jack.
Well it's getting late on Sunday night but I managed squeeze some building in. I was so impressed by the show and tell at the Christmas Party that I was full of enthusiasm and renewed determination to get it done.
I added the top formers and one side of the turtle deck. As usual I don't follow instructions too well. I should have wet the turtle back to help it form but it looked soft and bendy si I didn't and I got one small crack. I will push it down and add some thin CA so I should get away with it.
Here's the fuselage drying until tomorrow.
Jack.
Lookin' good Jack. Keep moving!
I've taken the past couple of night's off from building, but I must get back at it......... tomorrow :)
But, I did receive my order from BUSA containing the kit for the SE5a Lewis machine gun, a very cool scale prop nut, and the decal set.
Anyway, back to you, Jack.
Robert
Hey Jack - all I can say is WOW...wish I had the guts (and probably the time...) to start a project like this.
The only problem will be that my hands knees and everything in between will shake when I will be flying it.
Waiting to see it fly.
Robert - Who are you planning to shoot with your machine gun?
I think you need an airsoft machine gun synchronize with the prop.
Bobby
Very nice clean and precise work.
Impressive!
Quote from: Bobmic on December 11, 2012, 07:51:57 PM
Robert - Who are you planning to shoot with your machine gun?
Bobby
Simple. Verner Voss aka Greg Cadez ;D
Well when I left off the last time I had finished one side of the turtle deck with just a slight crack. I pushed the crack closed and CA'd it and it just disappeared. So for the other side I decided to use some water as suggested but I also used some softer balsa. It conformed nicely but as I watched it all buckled and twisted. I immediately wet the other side to relieve the stress. What I ended up with looked like a potato chip. The front half looked salvageable but the back half I replaced. You can see the bow in the front half in the picture. Anyway despite a couple of attempts with false formers but nothing worked. So I replaced it also. The second photo shows the result. I think with the covering I'll get away with it.
There is progress and I have the nose blocks started. I just placed the stab and fin for proportion and the Instructor and student were handy so they could check out their seats. I have decided to put the rudder and elevator servos in the fuselage just over the wing moving them from the tail. I have also decided to put the ESC's in the nacelles near the motors.
Jack.
Some more work accomplished in between the annual cookie baking with my grand kids. I glued some scrap blocks on the nose and started to cut it down to shape. I tried to use a hand sander for a coarse finish to get it to size but couldn't hold the sander for long enough. Ended up using a block with some 50grit. Still took about 3 hours on and off to get it close. Will finish sanding when I have a canopy made.
I made a vacuum box some months ago but never used it so this will be the first attempt. I made a plug out of blue foam and have cover it with plaster for final shaping and sanding. I'm planning on coating it with acrylic varnish to give it a smooth finish. That's it in the background of the picture.
I also installed the servos so that will reduce some of the weight in the tail.
Jack.
Looks good Jack. When can we expect your arf's to come out? I'll take one.
Is that Glenn as the front pilot?
Hey Jack,
I was just looking back at the pictures of the plane at the beginning of your thread. Those nacelles/cowls are very curvy. It'll be nice to see them coming along. I assume you'll be building them from balsa. Are construction details shown on the plans or are you on your own when figuring out how to build them?
Robert
The nacelles are built over formers using 1/16" x 1/4" strips. It should be no problem just tedious. Because the stock is so thin I will have to be careful so as to minimize sanding. I'm going to use medium to hard stock. Covering will be more of an issue.
I have made some progress over the holidays. I installed the Golden Rods for the rudder and elevator.
I also finished the cockpit/battery hatch. I don't think the pilots are the correct size just a bit too large. Need 1:7 scale pilots.
The blue camouflage will be a challenge so I did some trial stuff on the stabilizer. I'm pleased with the look but I'm using three different manufacturer's film and all have different sealing temperatures. I have to watch the heat on my irons carefully.
I bit the bullet and started to experiment with my vacuum table. The plug I made was Blue Foam finished in plaster. The set up was a shop vac with a 5H.P. motor and some fairly thick PVC. In the interest of marital peace I used the 4 slice toaster for heat. My table is 12" square so I had to cut the plug along a natural joint on the prototype to make it fit.
The lessons are the table works fine a draws a tremendous amount of vacuum. The plug needs to be made of wood so it's back to square one on that front. finally the toaster will only work with small plugs and thin PVC. I could not get even heat all through the film so it's back to the oven for the next attempt..
Hi Rob, here are some pictures that the designer posted when he was building the original model. Any comments or pitfalls?
Jack.
Hey Jack! You'll have time to build a few more planes before the Spring at the rate you're going!
Nice work on the covering trial.
Those construction photos of the nacelles look very nice. I don't see anything wrong with the technique.
Quote from: Papa on January 01, 2013, 05:22:06 PM
The nacelles are built over formers using 1/16" x 1/4" strips. It should be no problem just tedious. Because the stock is so thin I will have to be careful so as to minimize sanding. I'm going to use medium to hard stock. Covering will be more of an issue.
I have made some progress over the holidays. I installed the Golden Rods for the rudder and elevator.
I also finished the cockpit/battery hatch. I don't think the pilots are the correct size just a bit too large. Need 1:7 scale pilots.
The blue camouflage will be a challenge so I did some trial stuff on the stabilizer. I'm pleased with the look but I'm using three different manufacturer's film and all have different sealing temperatures. I have to watch the heat on my irons carefully.
I bit the bullet and started to experiment with my vacuum table. The plug I made was Blue Foam finished in plaster. The set up was a shop vac with a 5H.P. motor and some fairly thick PVC. In the interest of marital peace I used the 4 slice toaster for heat. My table is 12" square so I had to cut the plug along a natural joint on the prototype to make it fit.
The lessons are the table works fine a draws a tremendous amount of vacuum. The plug needs to be made of wood so it's back to square one on that front. finally the toaster will only work with small plugs and thin PVC. I could not get even heat all through the film so it's back to the oven for the next attempt..
5.0 HP Shop Vac ?!! Yikes. That's 3700 watts! Is that a 240-volt machine? You could vacuum boulders with that much power.
Andy
Just about, I can't pull the frame off the table unless I switch off. Even the dimples show up. Vacuum is not a problem.
jack.
I had to go almost to the bottom of the page to find my blog. How active is this tread. Have been doing some work on the model but did not take any pictures. So here's a collection of progress to date.
I covered the upper surface of the wing and built in 3mm of washout.
I have started the strips for the nacelles, that's very tedious work.
I remade a plug for the canopy. The bottom is obechi and the top is hard balsa.
I need to fill in with some body filler to finish it off. Then I'll vacuum in two parts.
I bought two matched spinners from Maxx Products International (MPI). One
standard rotation and one reverse rotation. I also picked up props at Pinnacle.
I love contra rotating twins and had planned on this from the beginning as it
eliminates the need for right trust. Electric motors are so versatile.
Back to the tedium. Beats going out and risking the 'flu bug.
Jack.
Nice work and nice spinners.
I'm really impressed with the clean working table. ;D
Awesome, Jack!
Just take your time with the sheeting and try to do a nice job (as I'm sure you will). Your efforts will pay off. Also try to keep the clue away from the top surface or you'll never get the form smooth (talking from experience :))
BTW, I noticed your thread was getting pretty low on the page the other day when I bumped a couple threads, but I knew you'd be updating soon, so I left it there ;D
I should update my SE5a progress report too.
Managed to get some progress. The nacelles will be finished tomorrow. I finished the plug for the canopy vacuum and will be pulling a draw shortly.
I also started the cowls. The original was built up from scraps but I'm doing them from solid blocks of medium balsa. I will be carving out the inside once its finished on the outside. They are handed so I have to be careful to keep them separated. They are rough cut for now and I will finalize the shape once the nacelles are sanded. Sorry Ed didn't have a beer can.
Jack.
I guess the can of beans is a suitable substitute lol. They do both cause gas!
Jack,
You're a brave, confident builder sharing a plans build like this. What I've seen looks great and I'm impressed.
Your experiences with thermo vaccuum forming sound familiar.
Dad and I have been working on a plans built Cessna Bobcat about the same size as your twin for nearly three years and although I've learned a lot from the building, my part of the model is not good enough for public scrutiny. Our plans show a model for IC power, so electrification is the present challenge
I'm hoping you have already solved or largely solved this and will once again share some secrets.
1. Where will your ESCs be located?
2. How will you access the battery?
Pictures are really worth a lot of words so if there are any recent photos of your build, we'd love to see them.
Hi Bill, still working on it but it has slowed down somewhat as I'm doing the nacelles and it is decidedly fiddly. I have almost finished the second nacelle, about 1 hour away from filling and sanding and then progress should speed up.
To answer your questions I have decided to mount the ESC's on the centre of the wing on the upper surface. Just double sided tape to hold them in place. I looked at putting them near the motors but it was a tight fit and if anything went wrong it would mean cutting the wing to get at them.
The battery access is in the fuselage under a very big hatch so access will be simple.
Jack.
Hi Jack,
I've put my ESCs on the bottom of the centre section of the wing. The nacelles stick down far enough below the wing to protect the ESCs. I'm planning to build the hatch in the windshield area. Where did your hatch end up?
The hatch is actually the cockpit so it goes on top of the fuselage for about 8" x 4" so lots of space.
Jack.
What's going on here? Is Bill building the same plane?
Good to hear some activity on the Speedtwin again.
Quote from: piker on March 15, 2013, 10:44:28 AM
What's going on here? Is Bill building the same plane?
Good to hear some activity on the Speedtwin again.
I'm glad to hear about the Speedtwin again too. No, I'm not building the same model, but I have gotten back to building the Crane, aka Bobcat, aka Bamboo Bomber aka T-50...and since it's a plans build similar size to Jack's, I'm once again asking an expert (Jack in this case) how to do things. So much to build, so little time to build it!
Hi all, well I started back to work on the twin. I had to stop while I built the Norseman and then a Cricket. Both successfully maidened and are being readied for the winter. So I did my share of scratch building while I was away from the Twin.
I finally got up the courage to vacuum form the canopy. The result was a little disappointing but very informative. I made it 12" square and should have made it bigger for the size and depth of the draw I needed. I made a number of attempts before I ran out of stock. I went ahead with the best but managed to get glue all over the place so it is not a thing of beauty. I will come back and do a better one when I build a bigger vacuum box.
I have the stab and fin installed the wing is almost covered. and will start to cover the fuselage later today. I used a mixture of old and different covering and that was not smart. The covering job is very much a "stand off" affair.
Jack.
Looks great!
I really like the colours!
She's a beauty Jack. Where did you heat your plastic for the vacuum forming? Was your wife home when you did it ?!! Any domestic discussions that are worthy of publication??!!
Andy
I heated it in the oven.
She was out for the first ones but home for the rest.
The first one I let it heat too long and I got an impression of the oven rack on the canopy.
Does anyone know a good, inexpensive source for the film?
Jack.
Have you tried Plastic World on Sheppard Avenue (north side, just west of Dufferin)? I find them to be an excellent supplier of plastics and fiberglassing supplies.
http://plasticworld.ca/ (http://plasticworld.ca/)
Andy
Hi Jack,
Twin looks wonderful! Depending on how much clear plastic you need and how thick you need it, I may have enough left from my efforts pulling the canopy for the Crane. LMK what you need. I bought a fair bit of the stuff as it's cheaper in big sheets.
My vaccuum box is 12x12" too! And like you, the results were not entirely satisfactory. We'll chat at the pilots' meeting.
Well it's finally done!. I have to put two pins in the canopy and shrink a few wrinkles. Everything works and goes in the right direction. Balance looks good, neutral to slightly nose heavy. I may put in a bigger battery for the maiden.
Had a problem with the reverse rotation spinner. The thread was about 3/32" shorter and the nut was binding on it. The boss of the props I'm using is very narrow. I did not have a suitable die to extend the thread. I used an extra washer that had the same diameter hole. Ran up well with no vibration. Initially the cowlings and the spinners had an interference problem, quickly solve with some judicious carving with a # 11. That requires some recovering.
I have not put a meter on it but it seems to have plenty of power and with the reverse rotation no torque issues.
Next up is Laddie's Northstar, The Skywriter Scratch Build, and an Airspeed Courier.
I love building!
Jack.
Congratulations Jack! This looks fantastic.
What a wonderfully unusual and unique model. I can't wait to see it fly.
One question - where did you get your reverse rotation spinner from?
Thanks!
S
I bought them direct from MPI (MAXX Products).
They are the 44mm ones. Beautiful machine work except for the thread on the reverse one as I discovered,
http://www.maxxprod.com/mpi/mpi-291.html (http://www.maxxprod.com/mpi/mpi-291.html)
Jack.
Gorgeous!
Beautiful finish.
very nice work...can't wait to see her in the air.
Great build log. I want to see a wintery maiden video now :)
Blue camo will look perfect in front of a wintry ROGO background! Great job! Good luck with the maiden!
Very nice, Jack! Congratulations on an excellent scratch build! :)