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Jul 22, 2019, 07:32 PM
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onewonders's Avatar
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Build Log

Harvard C-FRWN 3830 Tony Nijhuis Kit


Time to build from a kit. Itís a CNC pack from Tony Nijhuis http://tonynijhuisdesigns.co.uk/Harvard66.html.

I fell in love with Harvardís in 2015 when I flew in a two plane formation as the passenger.
I had started a scratch build in 2016 but it become a very complicated build for my skill level. So I am hoping this will teach me a thing or two.
The decals are from the plane that flew in the formation. My father-in-law was in this plane.

Specification
Wingspan 1676mm / 66"
Length 1100mm / 43.5"
Electric Motor 595 kV
Radio 6 Function
AUW 3.7kg / 8.25lbs
Wing Load 32 oz/f
Prop 14x7 wooden
ESC 70amp
UBEC 5amp
Battery 4S 4500mah

I ordered the kit on Tuesday last week and seven days later here it is!
The pieces are not identified. But thatís trivial. I didnít order the wood kit as I have lots of balsa and spruce.
This will be a rainy day project as there are still a lot of nice flying days left.
Wish me luck.
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Jul 31, 2019, 11:40 AM
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Letís get started


I needed another sheet of metal to complete the building board. Picked it up yesterday afternoon. Now I have three building boards for three projects. One will take years the others not so long.

I decided to start with the fuselage.
As per instructions and the build photos the fuselage side mid sections S1 & S2 were glued together. I’m using titebond II. The two pieces together are slightly longer than the plans by about an 1/8”. So I lined up the stabilizer seat as the priority.

I then marked the position of F3, F3 and F4 on to WS1. With the formers on their sides and lined up with the plans F2, F3 and F4 were glued to both WS1 to form a structure.

Once dried a bit i began to line up the fuselage side mid sections to learn the challenges to be expected. I’ll glue those tonight.
Jul 31, 2019, 03:00 PM
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Zipman's Avatar
Hi Doug, Great subject to model. I have been recently looking at Tony's plan and short kit for the Harvard myself as if I don't have enough planes on my build list. I always wanted the Midwest Industries 83in At-6 kit (No longer made) but escalating kit prices and rethinking size brought me back to reality and a smaller scale model. Thanks for the build thread. I will be a long for the ride.
Cheers.
Stan
Aug 01, 2019, 11:52 AM
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onewonders's Avatar
Thread OP

Mid Sections, F5, F6, F7


Last night I finished glueing the midsections to F2, F3, F4.

I was wondering just before glueing, about the midsections as they bend from F4 to the tail. If I glued the midsections in place with the bottom (the fuse was on its side) flat against the board, and the top midsection hanging in mid air would this create any twisting action on the fuselage? Should I connect the end with clamps, then lift the bottom midsection up so that the tail piece is in its centred position, (in mid air of course). So I did that, holding the bottom midsection in place with a magnet.

Time to glue in F4A. This is half former, the bottom of the U is placed lined up with the bottom of F4, the longeron square is centred on F4. Easy, the tops of the U don't line up with the edge of F4, but a small bit of pressure, glue and clamps, its all good!

Now onto F5, 6, 7.

The Fuselage assembly was brought upright and lined up with the plans. To hold the assy in place, I use the magnetic system from http://www.airfieldmodels.com.
I noticed that a few of the magnetic holders were not 90 degrees so each was checked and retightened.

Magnetic braces were used to hold the previously glued sections lined up to the plan, but also to make sure that F2 and F4 stayed solidly in place on the table, while I adjusted and readjusted the positions for F5-7.

The parts on the CNC kit are not marked at all. No numbers, no lines for lining up the parts, but no big deal as the plans are very well marked. Before removing each part, I mark the part number and which way is up, on each piece. Then the part is removed from the CNC pack, with a serrated saw blade. A little bit of sanding on the edges, and the piece is placed on the plans to be marked up.

After placing all the parts in their place, lining them all up as per the marks, I use the square to ensure 90 degrees and that they line up with the plans. I also place a straight edge on top of F5-7 so I can see that the gradation is even from one to another.

The two tail ends of the midsections don't line up perfectly they are off by a 1/16", one longer than the other. No matter what I did, I couldn't get it perfect. When I glued the S1 and S2 together, they must have been off a bit.

The important point is everything must be 90 degrees, no twist. So I might have to sacrifice that 1/16".

Everything is then tightened into place. Then I walk away. Have some lunch, coffee, think about what I have done, and WHAT I HAVE forgetten, could do better and then go back downstairs and check it all over again. Then and only then will I glue this together.
Doug
Aug 02, 2019, 03:46 PM
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onewonders's Avatar
Thread OP
Quote:
Originally Posted by Zipman
Hi Doug, Great subject to model. I have been recently looking at Tony's plan and short kit for the Harvard myself as if I don't have enough planes on my build list. I always wanted the Midwest Industries 83in At-6 kit (No longer made) but escalating kit prices and rethinking size brought me back to reality and a smaller scale model. Thanks for the build thread. I will be a long for the ride.
Cheers.
Stan
Stan two Midwest T-6 builds just posted on Facebook group balsa model aircraft builders association page. Thatís a big plane.
Chad Veich has a photo of his displayed on one of the threads.
Aug 03, 2019, 03:31 PM
Registered User
Zipman's Avatar
Quote:
Originally Posted by onewonders
Stan two Midwest T-6 builds just posted on Facebook group balsa model aircraft builders association page. That’s a big plane.
Chad Veich has a photo of his displayed on one of the threads.
Big, Yes. At one time I wanted to build a Ziroli At-6 (100 inches span). What was I thinking?
Yes the Midwest is just short of 7 feet span. That is why I am looking at Tony's design. I wish he had used construction like the Ziroli and the Midwest kits using a center crutch so you could build the top or bottom flat on the board with the formers cut horizontal instead of one piece.
How is the wood supplied in the short kit? Is it Lite ply or something else? Laser cutting would make the cuts a lot smother then I see from your pictures.
Great progress in a short time. Keep it coming.
Stan
Aug 03, 2019, 03:59 PM
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onewonders's Avatar
Thread OP

two mistakes high



Well what a noob...

Woke up in the middle of the night, staring up at the ceiling...knowing that I did it again. won't know until the morning, didn't want to wake up the wife.

Yep, see first photo. The gradation between 5, 6, 7 isn't continual. .

How did this happen? What did I do wrong?

So this morning I cut the former out using the ultra fine razor saw...It came out quite nicely, very small kerf on this blade.

I put the former up against the plans, and the lines were right. Then it hit me, the fuselage mid sections are angled up, so if I turn the former facing the wrong way the height of the top of the former now changes.

So the former was sanded down on the sides, the midsections sanded both just a little bit to remove any PVA glue and to allow a better bond.

I lined up the former to the braces, fitted it twice and then glued it. What a bugger! I would slip forward, changing the height, it would twist, changing the height.

I figure you guys having done this for so long have a trick...(don't you)...LOL

Anyways its now gluing in place, the 1/4" stick of basswood shows it is angled correctly.

Now for 2nd mistake. Earlier I had written that the midsections weren't lining up right. Well I sanded them to 90 degrees of the plan, using a square to check and recheck. 1/4" was needed to make it perfect. i added a 1/4" piece of balsa to make up for the lost wood. It all lines up now, without an increase in weight.

So then ..did I have the F1 in place properly, there is a hole for the position of the motor...did I have it facing the wrong way...SWEAT poring out while I measured...crap it's wrong....WAIT I am measuring it upside down.. PHEW...its all good. Time for a scotch.

Zipman, they used liteply and aircraft ply and some balsa. I think a laser would be cleaner, but a quick sanding does the job. From what I hear you have to sand off the burn from a laser, so its all good.
Aug 08, 2019, 11:48 AM
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onewonders's Avatar
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All strung up


Havenít been able to spend a lot of time on the Harvard. I am cleaning up my space in between glueing. Plus the weather has been so nice outside.

So last night I put the top stingers on with the exception of the stringers between F1 and F3.

F1 i had just glued into position but before glueing I did a test fit. There is quite the significant twist if I am to follow the notch cut out lines when the stringer reaches F3.

I might have to use some windex or hot water to ease the pressure as I put them in place.

While working on F1 I realized I need to make a motor box. Iíll use 3/16Ē birch airplane ply for that. So I will put the box in place plus the servo braces before I shirt the fuse.

I also need to determine how to manage the battery. I found a thread on the modelinguk site he has a good solution for the battery https://www.modelflying.co.uk/forums...?th=138111&p=5
I just want a better hatch.
Aug 15, 2019, 06:12 PM
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onewonders's Avatar
Thread OP

Progress on Fuselage


I've cut out a motor box, needs some tweaking. I took some advise and got a jewellers saw, amazing accuracy and straight cuts.
I was at an airfield where my Model's model is stored. Got a few extra shots.

Bottom longerons have been glued into place.
Built a battery box. The battery box was copied from the build log on the UK site.

F3 inside circle was cut square at the bottom, to fit the battery box. This will be beefed up a bit with some 1/4" bass wood.

At the moment I am in a bit of a quandry.
I really want to make a full length canopy hatch platform, from F2 to F5. The canopy, pilot seats, roll bar, F3 to F2 would all be on this platform. ...yes this would add weight...I really just want improved battery access and cleaner hatch.

A thin ply platform with the top of F3 removed from the fuselage and added to the platform along with the longerons between F3 and F2. The platform would sit on the longerons between F3 and F5 (and I would extend this longeron to F2).

The canopy would be attached to this platform. Magnets on the back to hold in position, two small dowels for the front at F2.

So my concern - would cutting the top of F3 reduce any torsional or torque strength from the fuselage, or is F3 just for maintaining the shape?
See my bad mock-up image

What do you think?
Aug 23, 2019, 06:01 PM
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onewonders's Avatar
Thread OP

Centre Wing et al


The motor box has been smoothed out 90 degrees all around. I've mounted the box as per the instructions, top and bottom left hand side with two washers providing 2mm of angled thrust.

The battery box was smoothed out and I have determined where the esc will live.

Continuing on with the wing centre. I found a few challenges that others should be aware of. The plans show LE1 and LE2, called bridge pieces - the construction notes are quite different than the plans. The 1/2" piece that is cut to shape, fitting in between the inner leading edge "the bridging piece LE1 that links the stepped leading edge at W2" - its hard to determine way to place this piece. Other build logs have the builder following the construction notes.

The other point I was challenged with was the retract braces. The holes were not big enough so to enlarge I decided that the bottom edge would remain untouched - the top and sides would be opened up with a #11 blade, carving carefully. Then a quick file to smooth it all out.

I've bought the retracts, they will be tested out this weekend - then start on the outer wing panels.

I still haven't decided what to do with the fuselage, so far no opinions. Should I cut out F3 and create a full length canopy/hatch? See last postingopcor n:
Aug 29, 2019, 01:39 PM
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Thread OP
Retracts didn't fit. Ordered another set this time from a FMS 1700mm P-51D Arf. I figured that since the two planes are from the same family that the retracts would be similar. They look the same. The problem was finding the specs.
Every website that sold the retracts, I would imagine, assume that you are buying the units to replace what you have broken. They don't think that us builders would want to use the set in our planes(?).
So after three days, I came across an ebay post for the exact same retracts with the exact same name and image as it was on a main hobby website. I clicked into the link, and found a link to the manufacturer. The manufacturer had the specs. They should fit!
I was also to begin on the outer panels, but realized I didn't have enough 1/4" sq spruce for the spars.
So I had to contact my local guy - yep I have a guy - he cut up some 1/4" spruce for me; I picked it up last night.
When returning my retracts to the local HS, I picked up the six servos that I need for this plane, two ails, two flaps, one rudder and one elevator.
So I have all the electronics, and surface control pieces. Before wrapping the fuse in balsa, I will place everything where it needs to be. Test, then remove and continue on!
I will finish the wings first, so I can make certain that the wing saddle is perfect, then complete the fuselage.
Doug
Aug 29, 2019, 08:48 PM
Registered User
Zipman's Avatar
Doug, Amazing progress. You have done a great job detailing the build sequence.
I read Geoff's build thread you posted in #8. Someone mentioned the wheels were supposed to be 3.25 inches but only 2.75 or about 70 mm would fit. I was surprised Tony N. did not specify a specific brand and part for the LG. I have to say I liked the Robart gear for the Midwest AT-6 kit
Aug 30, 2019, 09:36 AM
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onewonders's Avatar
Thread OP
Thanks Zipman - Wow I like the look of those retracts, they have an electric and air version, but the format won't fit this plane.
Tony N's comment in the build log is fit whatever retract you want. LOL.

The retracts that Geoff found were from HK and they only accept a maximum 2.75" wheel.
The ones I found will allow a 3.25" wheel and come with the wheel so this should work!
The plan shows a 3.5" wheel will fit.

They will arrive in a few days or so - I'll update then.
Aug 30, 2019, 08:08 PM
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Zipman's Avatar
Quote:
Originally Posted by onewonders
Thanks Zipman - Wow I like the look of those retracts, they have an electric and air version, but the format won't fit this plane.
Tony N's comment in the build log is fit whatever retract you want. LOL.

The retracts that Geoff found were from HK and they only accept a maximum 2.75" wheel.
The ones I found will allow a 3.25" wheel and come with the wheel so this should work!
The plan shows a 3.5" wheel will fit.

They will arrive in a few days or so - I'll update then.
Those retracts look pretty good.
Sep 03, 2019, 08:47 AM
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onewonders's Avatar
Thread OP

Moving onto the wings


I picked up some more 1/4Ē spruce for the spars. As per build log laid down the middle spar first.
Each rib was cut out of the short kit with some minor sanding to smooth out the holding pieces.

Held In place with the magnetic braces and used individual magnets to keep the ribs 90degrees to the spar and table. I did half of the starboard side then the other half of the starboard side as I didnít have enough clamps. Glued with gorilla yellow glue PVA(?).

Once dried the top front top middle and top trailing end spars were added.
Some of the cutouts in the ribs needed to be sanded deeper so the spar would fit.

A dihedral guide was cut out using my jewellers saw based on the drawing on the plans. Then sanded to perfection.

The build log showed a dihedral guide that was reverse of the one from the planes this was a bit confusing at first.

To make certain that I was cutting the spars to the proper angle with the dihedral guide, I would match up the center section against the outer panel once in a while.

After all of the glue on the top spars were drying the LE 3/16Ē balsa from W5 to W14 and the aileron TE 1/4Ē balsa from W8 to W14 were glued in place. Shaving and planing them down to shape will be fun!
The balsa used was from the scraps of the short kit.

Next step is do the left outer wing section. Then put the aileron and flap servo bearers into place. Thatíll be this week.

I havenít received the retracts yet so until I do the three sections will remain separate.

However thereís lots to do on the fuselage and building the tail pieces.
The plans have the elevator pushrod and control horn setup on the external elevator.
Iíve seen setups with the piano wire between the two elevators bent into the fuselage to allow internal control ďhornsĒ.
Iíve drawn this out on the plans there is enough room for the geometry. The elevator requires 12mm movement which is 10degrees. Lots of space to experiment with this idea. See drawings.

Anyone have any experience with this setup and what should I be concerned about?


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