Jump to content

Electrifying the Oodalally


kc
 Share

Recommended Posts

The Odalally seems high on the Mass Build voting so it might be chosen. Whatever the chosen model is many of the builders will probably want to have an electric plane but electric motors are much shorter than glow. Some people have electrified glow models by putting a ply box onto the bulkhead, others by putting the motor out on long bolts and spacers. However this prevents the lipo from going well forward.

My view is that minimum weight is an essential part of electric flight if using modest size Lipos. Therefore I want to eliminate lead ballast and use the Lipo up forward to balance the model. Of course it all depends on the model and also what size Lipo you use. Until the model is covered it's difficult to predict where it will balance. So a design where the Lipo can be moved fore and aft as needed is what I want.

I have therefore considered moving the bulkhead forward about two inches and produced a rough drawing of the front area with relocated F1

I hope this mutilating of his design does not offend Peter Miller!

oodalally1.jpg

Link to comment
Share on other sites

Moving the bulkhead on a plane with tapered nose means resizing F1 if the original shape of the plane is to be retained.

Therefore I have prepared a drawing of the resized F1. The way the new size was calculated was by the simple means of measuring the fuselage side and top view at the new position.

oodalally2.jpg

Link to comment
Share on other sites

For those who do not have the original Oodalally plan this is a copy of the fuselage front part for comparison.

oodalally-orig.jpg

 

You can see that the outine is similar and the u/c blocks etc would be just the same in an electric version. F2 would merely need an extra hole low down to allow the ESC to Rx cable to pass thro.

 

Of course you are all thinking this is premature and the Oodalally might not be the selected design. Well the reason i am posting this now is to suggest that a similar method could be used to electrify the other designs too.

Edited By kc on 11/11/2015 21:54:59

Link to comment
Share on other sites

You will see from my drawings that I have proposed using a Liteply battery tray to hold the Lipo and stiffen the fuselage. I have used this method on several other models. It's much easier to cut this part to shape complete with alternate holes for Velcro straps and connectors BEFORE gluing in place. the alternative holes allow the lipo to be moved back if necessary.

One of the advantages of making a drawing of any changes before starting to cut wood is to find any snags first. One of the possible snags would be that extending the fuselage sides right up to the nose means the balsa needs to be 39 inches long. Therefore you can see I have proposed a joint line where it will be lapped by the 1/32 ply and also the Liteply tray. Better here than at the tail end.

  • Like 1
Link to comment
Share on other sites

I built one veggie powered. I use a 6s 4000mah lipo and still needed lead upfront. I've moved F1 forward as well but I think the best idea someone suggested was to lengthen the nose an inch or two to help bring the CG to the correct position and keep weight down. My landings are obviously faster because of the added weight. Also cooling IS an issue with the ESC as I've burnt mine out once already. Just thought I'd add my 2P's worth.

Link to comment
Share on other sites

Thanks, Peter you are right.

Cooling of the ESC is allowed for because instead of having a piece of 1/2 inch balsa right across under the cowl area I have drawn just 1/2 inch doublers to allow a curved shape to be carved. The central portion is open, even under the motor to allow air to flow. Hopefully this should allow air to enter the ESC area as noted on my F1 drawing. ( F1 is not full depth on my version) The ESC section has a separate hatch. Slots will be cut in the hatch to allow air to exit. Actually just having slots cut in the hatch has worked on my other electric models.

I always intended to build the Oodalally right from the time it was published, if it is the Mass Build subject i will build it now but if the Ballerina is selected I will build that at this time.

Edited By kc on 12/11/2015 11:18:04

Link to comment
Share on other sites

Anybody building an Oodalally should note some slight amendments mentioned in Peter's original thread. The notes I made on the plan at the time were:-

R2 should be 242mm long

R3 should be 231.5mm long

Also in the written instructions THE WINGS centre column page 65 last line should just read " trailing edge strip" not "trailing edge capstrip"

It was suggested that the u/c 1/4 ply vertical blocks could me made more easily if they were laminated from layers of 3mm to produce the hole rather than drilling which requires more precision. It was noted that the hole only needs to be about 1 inch deep not full depth as shown.

Link to comment
Share on other sites

Posted by kc on 12/11/2015 11:17:39:

Anybody building an Oodalally should note some slight amendments mentioned in Peter's original thread. The notes I made on the plan at the time were:-

R2 should be 242mm long

R3 should be 231.5mm long

Also in the written instructions THE WINGS centre column page 65 last line should just read " trailing edge strip" not "trailing edge capstrip"

It was suggested that the u/c 1/4 ply vertical blocks could me made more easily if they were laminated from layers of 3mm to produce the hole rather than drilling which requires more precision. It was noted that the hole only needs to be about 1 inch deep not full depth as shown.

In fact I now just cut a slot in the 1/4" ply uprights for the u/c MOUNT INSTEAD OF DRILLING THEM

The trailing edge capstip is correct. You pin the leading edge sheet down and the capstrip Then the lower main spar and then you glue the ribs to the spar and capstrip. The 1/4 sheet trailing edge is not glued down until the ribs are in place.

Link to comment
Share on other sites

Shane, that's interesting. perhaps you could let us all know a bit more - total weight, covering material etc.

I made the assumption that Oodalally might be correct nose length as original design.

I have just finished and flown another model ( an own design I call ' RAPIDO 300 ' a 50 inch 'stick' type model for 300 watts ) where I used a long nose and eventully found the 3S2000 Lipo needed to go right back and I could have lopped about 2 inches off the front! In this instance keeping the servos well forward, some nice lightweight 3/16 balsa for the tail parts and a short moment arm made a tail light model.

It is difficult to tell until the model is covered and all the fittings are in place. Horns, clevis, tailwheel etc at the tail end can make all the difference.

Link to comment
Share on other sites

The original Oodalally thread is here and shows Peter's photo of the u/c blocks and he explains how the holes are staggered ( not shown as staggered on the plan- but stagger is essential for the u/c wires to pass each other)

Delving into the thread shows how models can vary even when built from same plan.

Shane says his model weighs about 6 lbs and needs a 6S5000 at 1 lb 5 ounces to balance. his model seems to have a built up tailplane and is glasscloth covered in parts. 27.6 oz / sq foot  while Peter said his own model was 19.26 oz/ sq ft ( but Shane extended the span to 56 inch so maybe the wing loading is actually a little less than 27.6)

Richard Scarborough built his for electric and said it balanced spot on with a 4S3300 Lipo. Seems to be built as per the plan except for motor.. . Probably about 12ounces for that Lipo- with motor too it would be about the same as the SC32 Peter used. So that seems to tie up and make me think standard nose length would be OK.

However it takes quite a lot of lead to balance up a rearward CG. It's much easier to build a longer nose and then just move the Lipo back! So I have drawn up another slightly revised front end plan 1.5 inch longer. It is not quite as easy as it sounds as all the lines are tapered. This is my new drawing. Time will tell if it mucks up the nice looks of the original.

oodalally3.jpg

 

 

Edited By kc on 13/11/2015 18:50:09

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...