Thread Tools
This thread is privately moderated by ChrisS, who may elect to delete unwanted replies.
Aug 11, 2013, 06:53 PM
Really?!?
ChrisS's Avatar
Build Log

DH.90 Dragonfly


-----Soooo, I've been wanting to do a large-ish scale project for a while. I still have a love for all things "two". So why not a twin engined biplane?

I looked around at the available offerings for plans and settled on Ivan Pettigrew' newest creation, a 74 inch DH.90. A beautiful plane, one of four different models of it's general type produced by the British de Havilland company in the 1930's. The Dragon, Express, Dragon Rapide and finally the Dragonfly.

This will likely take a while but I'll post pics here as I progress, along with observations and nuances of the general build.

So far I have pretty much finished the fuse, Upper wings and empennage pieces. The most interesting detail so far has been the "Frise" ailerons. These do good things for planes that would otherwise suffer from adverse yaw. The designer has also added another detail to tackle the known issues of the long thin wings of the DH.90 by adding washout. These features and several others should yield an airplane that is well mannered and easy to fly...I can't wait.

The wing loading is stated to be 13.7 ounces/ft^2. Mine will be a bit heavier as I need the wings to come apart for transporting. Hopefully I won't add too much weight in the process...the woes of driving a small car.

-----I have been working on the Drangonfly a bit. I finished the upper wing by creating a center section that will afix permanently to the fuse. The wing outer sections connect with a carbon tube-in-tube and anti-rotation pin arrangement.

The lower wing is shown built up as per plan (except for the outer sections not being attached to the inner section) minus the sheeting. The split flap was kind of fun to do as I had never built this kind of a flap before. When closed, the whole flap hides inside the wing nicely. Hinging will be of a tape and/or covering type. Connection of the outer lower wing panels will again be carbon tube-in-tube but the tube in the outer panels will pass thru the wing spar and will run alongside the inner panel spar.
Last edited by ChrisS; Oct 29, 2013 at 11:22 PM. Reason: Adding on
Sign up now
to remove ads between posts
Aug 16, 2013, 10:32 PM
Registered User
Nice looking work!!!
Aug 26, 2013, 03:14 AM
Registered User
Trevorh's Avatar
Nice work on the split flaps. Any particular reason why you placed your carbon joiner for the upper wing on the trailing edge rather than the usual mainspar position?
Aug 26, 2013, 10:14 AM
Owner - Flying Models
Chris,

It is looking good!

I would encourage you to make new posts to your thread, rather than edit your first. It makes it a lot easier to follow along and find the latest photos.

Thayer
Aug 26, 2013, 03:34 PM
Really?!?
ChrisS's Avatar
Actually, that IS on the main spar of the wing Trevor. It's just hard to tell because the leading edge sheeting comes all the way back to the spar. Unless your talking about the center section that will be glued to the fuse. There is no spar in there, just the carbon tube and ply-reinforced balsa.

I really like the split flap on this, it came out nicely...thanks.

Chris
Last edited by ChrisS; Aug 26, 2013 at 07:48 PM.
Aug 27, 2013, 03:10 AM
Registered User
Trevorh's Avatar
Ah, I see. I had you flying backwards there for a moment!
Sep 08, 2013, 09:08 PM
Really?!?
ChrisS's Avatar
I finally freed up some time after a couple of weeks away. I just about have all the woodwork done now. The build has been fairly straight forward with only a few minor exceptions which were easy to sort out.

I need to take a few more pics as the plane is a good deal further along than I have pics to show. I'll do that and post them later.

I decided to use a pair of Hacker A30-14L motors that I had on hand from my previous XF5F build. These are a good bit more powerful than the designer states the plane needs, but I just could not find any 450-480 sized motors that gave decent efficiency at the levels I wanted to run them. These will turn 11" props on 4S at better than 80%, which should be a good match for the plane. They took a bit more persuading to fit, but nothing serious. Plus, you know, extra power is always good.

Chris
Last edited by ChrisS; Sep 08, 2013 at 09:18 PM.
Sep 09, 2013, 03:33 AM
Registered User
Trevorh's Avatar
Coming along nicely Chris. That undercarriage arrangement is an Ivan trademark!
Sep 09, 2013, 08:34 PM
Really?!?
ChrisS's Avatar
Thanks Trevor. It does seem a good way to build an all in one nacelle assembly. A bit fiddly at first, but once you get the basic geometry of the thing figured out it's simple. I did add a stick or two and covered most of the joints with filled epoxy (I guess that shows). It seems strong, so long as I don't pound it too hard.

Another weekend should see the woodwork finished.

Chris
Last edited by ChrisS; Sep 09, 2013 at 08:42 PM.
Sep 15, 2013, 10:38 PM
Really?!?
ChrisS's Avatar
A good weekend! All of the structural part of the wood work is now done, huzzah! Still lots to do though, shaping, radio installation, covering etc. I'm starting to see the light now. Looking forward to that first flight. Need to get a 14 channel receiver ordered...

Chris
Sep 16, 2013, 03:49 AM
Registered User
Trevorh's Avatar
Steady on, it looks like you are going to complete this build in less time than it takes me to clear enough space in the workshop to get started!

Do make sure to take some pictures of it fully assembled before you start covering - should look beautiful.
Sep 16, 2013, 11:37 PM
Really?!?
ChrisS's Avatar
Oh for sure Trevor, I'll take good shots of each of the finished parts and the whole assembly. I love the skeletal look too...almost a shame to cover it up.

Chris
Oct 11, 2013, 08:42 PM
Really?!?
ChrisS's Avatar
Oooooohkaaaaay, it's been a long two weeks, partly good and partly bad. The bad is that I have been furloughed thanks to the govt. shutdown. The good news is that I have had lot's of time to work on the Dragonfly. At this point, it needs only a few more hours to finish up. I'll let the pics speak for themselves.

Chris
Oct 12, 2013, 03:47 AM
Registered User
Trevorh's Avatar
Looking great!


Quick Reply
Message:
Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Build Log De Havilland DH 2 / AIRCO DH 2 /AMC DH 2 scale 1:5,33 , Peter Neate drawing. bth Scale Kit/Scratch Built 198 Jan 10, 2016 12:11 PM
Wanted Like 90 Blades for Dragonfly/Hummingbird Ragwing Aircraft - Electric - Helis (FS/W) 0 Jan 17, 2006 10:38 PM
Sold GWS Mini Dragonfly with Airtronics Radio RTF Like 90 Blades RTF Matt Chester Aircraft - Electric - Helis (FS/W) 3 Jul 28, 2005 09:12 AM
DH-90 Dragonfly LenBFP Scale Kit/Scratch Built 7 May 24, 2002 07:03 PM
DH-90 in FMS, does it exist? vectorbeam Scale Kit/Scratch Built 4 Mar 07, 2002 10:07 PM