d&mrc

I can't seem to find anything anywhere (at least not anything that is intended for rc). Do any of you know where I can find a kit or plans for this aircraft?

Red Scholefield

Here is a start. Should make an interesting model with the negative stagger between the wings.

d&mrc

I was hoping for something with a little bit more detail....

Red Scholefield

What, and limit you freedom of construction design?

Yak 52

Try this too
http://www.scribd.com/doc/4665305/Ai...-Havilland-DH5

You'll probably have to scratch build...

Yak 52

This site seems to do a laser kit for a large rc dH5 in their misc section
http://www.lazer-works.com/

d&mrc

Ow, it will still be custom, don't you worry. LOL
The thing is, when it comes to scratch-building, or even working off plans, I tend to screw-up. I intend to use whatever plans, pictures, and specifications I can find (after scouring the internet, I have given up hope of finding any sort of kit), then work with these people to get a kit made. it is going to be 10.5% scale. Why 10.5? because that gives me the one yard (okay, not exactly one yard, 36.12in) wingspan I want. So far I have wing area, length, and height calculated. Yak-52, you have provided me with a set of complete specs, so now I can work out the height of the vertical stabilizer, elevator-span (never thought I would say that,lol), etc. Thank you very much.
Question: Should I make my dihedral 10.5% of that on the full scale, or stick with 4 degrees?
I won't begin the building process until the middle of May, but I want to get everything together now.

d&mrc

Holy smokes, I have been searching for days! How did you find one?! It's a bit big for me, I'll have to ask them if they'll cut a kit in the size I want.

Yak 52

no problem...
Stick with 4 degrees.

You might want to increase the tail plane and fin areas slightly with a model of that size and type - depends how 'scale' you want to go.

In terms of scale some things (lengths, spans) will be a direct percentage, but scale wing area will be square root of original. Scale weight would actually be cube root of original. Not often possible in practice - but if you could do it the model would fly at scale speed (incredibly slowly).

Angles (dihedral, wing incidences) would theoretically be the same but in practice you can choose what will fly best. i.e. if u needed to increase the dihedral to 5 deg to improve stability it wouldn't affect appearance much.

Jon

Yak 52

Quote:
"In terms of scale some things (lengths, spans) will be a direct percentage, but scale wing area will be square root of original. Scale weight would actually be cube root of original. Not often possible in practice - but if you could do it the model would fly at scale speed (incredibly slowly)."

Sorry that's wrong!

Actually areas should be scaled by the square of the original scale factor ie at 1/5 scale, wing area would be 1/25 of original. Weight should be scaled by the cube of the linear factor ie at 1/5 weight would be 1/125th of original...



Explanation here:
http://www.capable.ca/stefanv/rcstuff/qf200210.html

Your scale is 1/9.524 (!) ie 10.5%

d&mrc

Wow, you must be physcic, because you answered my next question! So, with a full-scale wing area of *pulls out calculator* 2545.2 sq in, my models wing area should be.......267.2406551868962620747585048299 sq in, or as close as those cutting machines can make it Does that sound right? I used fractions for that, but using the percents is easier (on a calculator, at least) so I shall stick with those. Now for my weight. I think I'll make the kit's weight to scale for the empty weight of the actual aircraft. Which comes out too......

1/862.801408x1010lbs=1.1706054126lbs AKA, 18.7296 oz

Whew, as someone who hates math, I can officially say that that was an ordeal! But, I have my wing area, and weight. After some more thought, I have decided that I am going to have a custom kit made, even though that one place already has a kit version. It just has a certain appeal....

Yak 52

We aim to please...!

Yak 52

I make that about 1.85ft2 for area, so at 18.7oz that's 10oz/ft2 wingloading, as near as dammit!

However... (there's always a however)

A biplane's wing area is less effective than the equivalent monoplane - about 85%.
http://www.rcgroups.com/forums/showthread.php?t=504677

So imagining that your wing area is 1.57ft2, your wingloading's going to feel more like 11.5oz/ft2

Which is still fine - she'll be nice and floaty - but then she's a bipe!
Loads of drag though, so you might need more power than you think...

d&mrc

Ow ya, I forgot to square my scale.Duh! And, regarding the high drag, isn't that characteristic of just about all biplanes? I wasn't
expecting a speed demon out of this, nor an amazing aerobat, I already have those.
Anyway, I'll keep crunching numbers. Once I have a complete list of specs, I'll run them by you (and anyone else reading this).
Edit: Damnit, just found out that the full scale wingspan is 308 in, not 344 like I initially read. That changes my scale....

Yak 52

So you are looking at 1/8 or 1/9th then? 34.2 or 38.5" respectively...

Re: 'high drag characteristic of biplanes'

Yup, that's what I meant...

d&mrc

Well, my original goal, as you know, was a 36 inch wingspan. That came out to be 11.688311688311687%. I rounded it off to 11.7% for the sake of simplicity, which gives me a 36.036 inch wingspan. How are you getting the fractions (math has always been my weak point, thank goodness for computers!)?. I figured out my fraction, then forgot it, and how I got it
So far I have calculated everything except the tailplane area, the fin area, the rudder area (the full-scale specs consider the control surfaces seperate from the rest of whatever they are attached to, i.e, aileron area and wing area are separate), the aileron area, and the elevator area. Everything else is done, however I am going to double and triple check my numbers before I post them.

Yak 52

Full size span / intended span = scale
308" / 36" = 8.5555555555
or 1/8.55... scale

Or...
If I want to work to a particular scale and if model span is not too important:

Original span / scale = model span
308" / 8 = 38.5" span
308" / 8 = 34.2" span

I suppose it depends what is more important to you - scale or model span.
e.g. a free flight Peanut class model will have a 13" span whether it's a cessna or a 747 - different scales though!

I think most RC scale modellers would build to 'a scale' though e.g. 1/3, 1/5 etc
But 'tis up to you!

Yak 52

Re:
"(the full-scale specs consider the control surfaces seperate from the rest of whatever they are attached to, i.e, aileron area and wing area are separate), "

Have you worked that out from drawings or is thst just the convention?

d&mrc

I worked that out from reading the specs. It lists "wing area" and "aileron area" seperatley, as well as "rudder area" and "fin area", and "tailplane" and "elevator area".

degreen60

You can find a plan or 3d on the net then get a tileprint program. Tell the program what size to make the plan and it will tileprint on 11x8 paper for you to tape together. Then instead of using balsa for formers use foam. It is easy to cut and is hidden when the model is finished. I just built a wing with balsa leading and trailing edges, wing tips, and spar. The ribs are cut from foam egg carton lids. I made a master rib out of plywood, laid it on the foam, and cut the foam with a knife. Took about 5 min to cut out all the ribs I needed. There are some pictures of models built with foam formers on the WW1 planes thread.

pburt1975

http://www.aeroaces.com/jamdrwgs3.htm
half way down the page, you can order the plan for 7.50 a sheet
DeHavilland Airco DH-5 WW-I Fighter
3-view, cross-sections, fuselage, wing, and tail structures, color schemes for 4 aircraft, aircraft unit allocations, performance, and DH-5 manufacturer's production quantities.
1/48 (21 x 30)..........$7.50
to order, see the How to Order section.

Yak 52

More interesting bipe stuff - particularly if you do go the own design route:

www.modelbouwforum.nl/forums/algemeen-modelvliegen/46394-vleugel-oppervlakte.html

d&mrc

Okay, I have finished figuring out the dimensions of my model. I have yet to work out my wind loading, power loading, and my stall and cruising speeds. I intend to round off all these numbers to the hundredth's place when it comes time to get the kit. For now, I wish to keep everything exact.
Scale: 1/8.547008547
Wing span: 36.036 in.
Wing area: 34.8412428 sq in.
Length: 30.888 in.
Height: 12.8115
Chord: 6.318 in.
Negative stagger: 3.159 in.
Dihedral: 4 degrees.
Span of tail: 11.7585 in.
Wheel track: 7.02 in.
Tailplane area (on either side of fuselage): 2.2011912 sq in.
Elevator area (on either side of fuselage): 2.0040696 sq in.
Rudder area: 1.0348884 sq in.
Fin area: .3613896 sq in.
Ailerons area: 1.9055088 sq in. per aileron
Gap between wings: 6.786 in.
Target weight without electronics: 25.88206608 oz
Target AUW: 38.23370554 oz.

I have gone over each of those calculations at least six times. I have decided to get a set of 3-views of the full scale aircraft from here, as well as one of their Fotopacks for this aircraft. My logic is that, as long as the general shape of each part is known, the numbers I have should make everything turn out perfect. I do have two more questions though.
After the dihedral in the full scale specs it says "30 min". What the heck is that supposed to mean? It also says: "incidence 2 deg., washing into 2 deg. 15 min, at port interplane strut". I know what port is, and what an interplane strut is, but what's going down after 15 minutes,and why is the starboard strut left out of the fun?

Yak 52

minutes are fractions of a degree

http://id.mind.net/~zona/mmts/trigon.../degMinSec.htm

I'll have a look at your specs and get back to you...

Jon

Yak 52

Could you post the original specs?
My 'puter doesnt seem to like that scribd page...
Cheers
Jon