Eagler's Nest

Airframes => Double Seaters => DE => Topic started by: rfeenstra on March 22, 2017, 10:13:21 PM

Title: DE (Cabin Mod) tail Modifications
Post by: rfeenstra on March 22, 2017, 10:13:21 PM
A few of you were interested in the modifications to my DE that I proposed a couple of months ago.  Well, those mods are well under way.  When I built my DE, I added a cabin which extended the wing span by some 32".  I seriously considered extending the tail but chose to build per plans.  I moved the firewall back by 5" to help compensate for the heavier A65 I was going to put on the nose.  CG wound up at the recommended 25% MAC, which proved to be too far forward as I needed a bit of throttle to flare.  I added 10 lbs. of lead to the tail and a 3 lb heavier tail wheel bringing the CG back to about 29% MAC.  A dead stick landing proved that I could flare w/o engine carrying almost no extra speed.  I decided to extend the tail to help get rid of the lead. So, I cut off the tail just behind the cabin and built an new tail and tail feathers.  Given the additional moment arm, I reduced the size of the tail to help compensate for the additional steel tubing needed for the additional length.  Here are the results so far.

The old tail weighed 23.4 lbs.  The calculated weight of the new tail (tubing length times weight/ft. plus  welding rod and fittings) is 29.5 lbs., 6.1 lbs more.  The new tail has an integral fin and that is included in the weight.

The old stab, elevator, rudder, and fin weigh 25.2 lbs.  The new stab, elevator and rudder weigh 19.2 lbs.  So, so far I'm about even with the weight of the tail feathers 26" farther back.

I decided to streamline the fuse dramatically, so I added formers and stringers to give the fuse shape similar to a Champ.  I estimate that the weight of all the wood will be in the neighborhood of 10 lbs.  When I disassemble for painting, I will weigh.  All said and done, I may not actually loose weight getting rid of the lead, but at least the weight will serve a useful purpose.  I flew this bird for some 3 summers.  I was getting bored!  Part of the fun in these projects is the initial build, and then contemplating, fulfilling, and testing modifications help keep the project interesting.  One can fly over the same territory slowly for only so long before boredom sets in!

Attached is a picture of the old tail (perhaps a wind sock pedestal?), and a few pics of the the new tail and tail feathers.  In the background you will see a bit of a 7GC which served as a model for the new tail.
Title: Re: DE (Cabin Mod) tail Modifications
Post by: Dan_ on March 23, 2017, 08:42:27 AM
Awesome mods.  Chief Eagle..!
Title: Re: DE (Cabin Mod) tail Modifications
Post by: ArcticDave on March 23, 2017, 11:47:37 AM
Looks great! Those formers are awesome. That will look really good when covered.
Title: Re: DE (Cabin Mod) tail Modifications
Post by: MrG on March 23, 2017, 01:31:28 PM
Well have to say thats better than i thought it would turn out - agree on the emp mods too
Title: Re: DE (Cabin Mod) tail Modifications
Post by: rfeenstra on March 23, 2017, 02:31:31 PM
Chief Eagle.  Hmmm.  I like that!
Title: Re: DE (Cabin Mod) tail Modifications
Post by: Dave Stroud on March 23, 2017, 06:51:51 PM
Very nice progress. An inspiration for sure. Could you please share the dimension from the aft wing strut attach point on the fuselage up to the bottom of the aft center wing part near the rear spar ?  Would a 5' 10" or 11" fella fit in there ok ?  Please keep pics and description of your mods as thing develop . Thanks.
Title: Re: DE (Cabin Mod) tail Modifications
Post by: rfeenstra on March 23, 2017, 07:08:02 PM
Dave, I can try to measure that.  i built the cabin so my head is not under the wing.  I used the dimension given in the plans.  Without the bottom of the wing over my head, I have excessive head room (I'm 5' 10'').  I actually considered lowering the wing by a couple of inches, but decided that would be way to much work as lift struts, fuel lines and who know what else would also have to be changed.  A 6' person would have no problem getting in or sitting in my plane.
Title: Re: DE (Cabin Mod) tail Modifications
Post by: rfeenstra on April 24, 2017, 06:36:36 AM
Progress.  Top covered, bottom is next.  Control surfaces are covered, stitched and taped.
Title: Re: DE (Cabin Mod) tail Modifications
Post by: rfeenstra on April 24, 2017, 07:06:45 PM
A lot of progress since I posted the last pics.  Couldn't resist putting the tail feathers on to see what it would look like.  Still have a lot of taping to do, but getting close to the painting job.  Don't like painting!  Maybe I'll be flying again in a month or so.  Then again, maybe I'll make doors which will delay me another month.
Title: Re: DE (Cabin Mod) tail Modifications
Post by: stevejahr on April 25, 2017, 03:29:33 PM
That looks like a proper little airplane
Title: Re: DE (Cabin Mod) tail Modifications
Post by: rfeenstra on May 14, 2017, 06:13:56 PM
painting has begun!  First cross coat of color.  Same color as before as I need to match the wings.  I may reduce the number of coats to save weight, leading to a slightly different shade of yellow.  But then, there were many shades to start with!  Yellow does not cover well and the depth of color gets better with every coat. But it adds up weight-wise.
Title: Re: DE (Cabin Mod) tail Modifications
Post by: rfeenstra on May 25, 2017, 07:52:10 PM
Tail installed and rigged.
Title: Re: DE (Cabin Mod) tail Modifications
Post by: s johnson on May 26, 2017, 12:46:20 AM
Looks really nice. The tail reminds me of the Sexy Areonca Sedan

Scott J.
Title: Re: DE (Cabin Mod) tail Modifications
Post by: 914pete on May 26, 2017, 07:13:57 AM
Really nice work!
Title: Re: DE (Cabin Mod) tail Modifications
Post by: PropMan on May 26, 2017, 01:58:09 PM
Looking Great!!!
Title: Re: DE (Cabin Mod) tail Modifications
Post by: rfeenstra on June 04, 2017, 02:43:55 PM
It fly's again!!
Title: Re: DE (Cabin Mod) tail Modifications
Post by: MrG on June 04, 2017, 03:32:57 PM
cant wait to hear how it fly compared to last time was it worth  it ?  
Had to of lost some drag and are the tail mods helping
Title: Re: DE (Cabin Mod) tail Modifications
Post by: John Reinking on June 04, 2017, 03:44:22 PM
Would you be able to post any information/drawings of the ply formers?
Title: Re: DE (Cabin Mod) tail Modifications
Post by: rfeenstra on June 04, 2017, 03:58:23 PM
only flown it a couple of times, so don't have a lot if info.  Initial impressions are that it is much more stable, less "tail wagging".  Remember that my original build extended the wing span by about 32".  I don't know how a DE built to plans flies.  It seems to find a very stable trimmed speed compared to how it used to be.  CG is actually farther back (about 31% cord) but yet more stable.  Not a Lot faster, maybe 5-7 mph.  The trim is effective to a lower speed as the tab is bigger but it is more sensitive at cruise speeds.  I was hoping to actually loose some weight given that I could take the lead out of the tail, but that didn't happen.  Actually added 15lbs.  Can't quite figure out where as my calculations said that I should have been the same to a couple of pounds lighter.  so far, though, happy!
Title: Re: DE (Cabin Mod) tail Modifications
Post by: rfeenstra on June 04, 2017, 07:22:32 PM
Flew it for nearly 1.5 hours this evening. Very happy!  Flew for nearly 45 min. hands off the stick - just using rudder.  Slight turbulence upsets it slightly but then quickly settles back down to trimmed attitude/airspeed.  A hard push or pull on the stick then releasing  gives maybe 2 or 3 oscillations then settles back into level flight.  Typical cruise used to be about 50 to 55, now 60 feels good at the same engine setting.  Elevator authority is very good even at idle.  I have to be careful because I stalled it a foot off the ground with engine at idle.  I'll have to change my landing procedure slightly.  Still windy in the cabin, of course.  Need doors!  Next project.

John, there are no drawings!  Everything was "design/build", "That Looks Good" engineering. I had the advantage of having a Champ derivative sitting right next to the build table.  The tail/formers are a copy with the necessary changes fit the desired dimensions.  Former shape was determined by using pieces of wood screwed together so that things could be moved as i determined the shape of the wood stringers.  When all was reasonably set (certainly not perfect - not that patient), the screwed together pieces were put on a piece of plywood with the stringer locations marked. Then the shape was drawn freehand.  Then it was filled with as many holes as I could justify while maintaining necessary strength. The added 26" to the tail was a calculated guesstimate of what would be necessary to get the CG where I wanted it.  Turns out to have been correct as I am at 29% of MAC empty, 31% with 200 lb pilot, 32% with pilot and full fuel (18 gal.), 33% with pilot, passenger and partial fuel.  The unfortunate part is that I gained more weight than hoped. 15 lbs over the old version with all of the lead.  My calculations, weighing, and hoping pointed to a similar or even slightly lower weight.  Obviously, my calculations were erroneous!

Got a new prop coming on Monday that will, hopefully, take better advantage of the low RPM 65 hp.  The prop I have now over revs by over 200 RPM.  Probably gives me more horse power on takeoff, but too low a power setting at desired cruise RPM.
Title: Re: DE (Cabin Mod) tail Modifications
Post by: John Reinking on June 04, 2017, 10:21:32 PM
Thanks.   Blue skies
Title: Re: DE (Cabin Mod) tail Modifications
Post by: Tom H on June 05, 2017, 05:32:36 AM
rfeenstra, that is one slick DE.  Get those doors on and you'll probably pick up a few more mph.

Regarding the tail wag of a plans-built DE (more or less), our DE Stubby does not have any tail wag.  It, too, flies well, hands off, on a calm day.

CG when I fly is about 28%, and we think a bit more aft would be good, but don't want to add any more weight.  Good to hear of results all the way back to 33%, though.

Great job!
Title: Re: DE (Cabin Mod) tail Modifications
Post by: MrG on June 06, 2017, 02:30:59 PM
it sounds like it work as it was supposed to - good news and thanks for sharing and feedback MrR
A hard push or pull on the stick then releasing  gives maybe 2 or 3 oscillations then settles back into level flight -
Thats really good and most RV's are like this good sign of a nice plane, Looks good and flies good "Double Bonus"
I dont get a lot of wag either - though i really can't fly hands off unless its a perfect day at cruise and its a lot of rudder work,
pitch attitude with power change is way more than a cub/skyfox
Mine is flown around 25.5 with just me in it and i like that - passenger i get 27.6 man you notice the difference on landing.

5 better than last fuse so far is a great bonus and about on par with what i thought you may end up with - waiting to
see if you do a 2 piece door or full
Wife has signed of on a new fuse but have to wait till Jan to start. to many other projects running i need to finish

@john we have 2 x J3 cubs here and been looking how they did there fues here are some fuse images i scoured of the net
if you look at the 2.jpg image dam looks like a cabin eagle fuse with modified tail, there is enough images and drawings in the zip file
to get enough info - as i choose to add weight to rear instead of chopping the nose - the new fuse will work with same over hange out front
and wont need all the lead i have up the back and get some of the empty weight down

Link to zipped images zip file (https://drive.google.com/file/d/0B9VI4wxJqXv6LUx4RjkzR1FpR28/view?usp=sharing)

the Kitfox , skyfox and Gazelle  are similar but more of a box section rear of  rear spar to tail -
i figure the smoothed out look - is worth that little more effort Just have to see how MrR's turned out "Hot"
MrR Any chance i can get a measurement from leading edge to rear post - ill compare the length to the cub and your new length
Title: Re: DE (Cabin Mod) tail Modifications
Post by: MrG on June 06, 2017, 06:00:17 PM
MrR
One last Q, what are the stick forces compared to the previous set up, if correct they should be a bit lighter ?  
Title: Re: DE (Cabin Mod) tail Modifications
Post by: rfeenstra on June 06, 2017, 06:17:21 PM
LE to tail post is 174".  My fuse is still shorter than a champ which is way shorter than a cub.  Cubs are a long airplane.  A friend of mine is in the process of covering his Cub and I was amazed that the fuse is almost 21 feet long.

Got the new prop on it.  I can finally get full power out of the engine, though I can't quite get to red line of 2300 rpm.  Probably will have an inch of pitch removed this coming winter. I'm now cruising at 70 mph indicated at 2100 rpm.  Way too windy in there at that speed.  Doors are next!  Probably a full frame door with a removable window.  I like looking down past the wheel so I may use Lexan for the whole thing.  A bit heavy, but...

Stick forces on the elevator are lighter.  I dont have to pull so hard in the flare.  Ailerons, of course, are unchanged and heavy.  I may look into spades to better coordinate all of the stick forces.  The horn on the rudder is shorter so there is less rudder pedal travel and definitely more pressure.  I like the added feedback, and the reduced pedal travel.  Seems to work good.

All of the changes I've made to the tail are a result of the extended wingspan due to the cabin.  When you change one thing, many things need to be redesigned.  In all fairness to Leonard and his initial design,  My DE is no longer a DE!  I like what I've done, but it was a lot of work.  Had I stayed with Leonard's design in the first place, without the cabin, none of this would have been necessary.  it's just that here in Northern country, no doors is just plain cold at 3000 feet, even on an 80 degree day.  Hense the desire to include a cabin with door hinges prepared for.  Now to just build the doors.
Title: Re: DE (Cabin Mod) tail Modifications
Post by: Dave Stroud on June 06, 2017, 06:22:33 PM
Good on ya, Dude for the nice work and even more for sharing real time info on how it comes out. You are venturing into areas where most won't head....Thanks...
Title: Re: DE (Cabin Mod) tail Modifications
Post by: rfeenstra on June 06, 2017, 06:29:19 PM
Thanks.  I thought this would be a good project to practice on before I start working on the 7GC I was using as a model for this project.  I have to do a major mod to the fuse on the 7GC in order to make it qualify as an experimental.  The mods will make it necessary to design all new formers and stringers.  I know I can do it now!
Title: Re: DE (Cabin Mod) tail Modifications
Post by: MrG on June 06, 2017, 07:26:16 PM
i Agree 100% if i started 6 months later i would of done a cabin, I looked at doing this but i wanted to go flying and pushed it to first flight in 18 months, also running a business 
My daughter made this happen to - I flew 3 weeks ago looking at logs 149 nm each way - i was at 5500ft about minis 5C  (23f) - that made me think and wife wont get in when cold
Mate said to me, only one way to stay in aviation is involve the wife, she been in a Aronica Chap why we were @ Taylor TX last year  and loved it - so she told me no cabin no ride.  

The info you supplied is awesome and sealed the deal - plus the wife thinks now yours looks like a plane :emoji_u1f601:  Its that mental thing too with her
i can get 64 knts @ 2100 i think thats 74 mph so you should do better with doors - i have spent so much time trying to reduce drag, even the 1/2 doors on mine made a difference
i do get 3300/3350 staring and level full throttle - plus mine is not a stumpy - running Franks Prop 

If i did my DE as a center stick and full bench seat - i would be happy your in behind the screen - but im happy to sit in it for 4 hrs and go somewhere, but have to make the boss happy too 
Thanks again for al the info MrR - I did not measure length of the cub yet so may not have to go as long as i thought - great work  
Talking with the regulators here now what we going to do when i do changes - New plane or just a fuse mod ? 
Title: Re: DE (Cabin Mod) tail Modifications
Post by: MrG on June 12, 2017, 04:08:26 PM
@rfeenstra one more Q
That looks like the tail of the champ, did you use same specs as your 7GC or scaled it ?
Title: Re: DE (Cabin Mod) tail Modifications
Post by: rfeenstra on June 13, 2017, 05:11:47 AM
It is somewhat copied. It is scaled down a bit and I added a little aerodynamic balancing on the elevator. The way the stab is mounted and the elevator control horn are copied from the Champ.
Title: Re: DE (Cabin Mod) tail Modifications
Post by: MrG on June 13, 2017, 02:24:51 PM
Thank you
Title: Re: DE (Cabin Mod) tail Modifications
Post by: rfeenstra on July 10, 2017, 07:23:00 PM
Been flying for many hours now. It is great! The added tail length, CG at about 31% MAC, increased stability for hands off flying, increased speed at lower rpm have made the plane a joy to take off, fly and land.  A lot of work, but well worth the effort.  Now for doors!
Title: Re: DE (Cabin Mod) tail Modifications
Post by: Dan_ on July 10, 2017, 08:11:37 PM
Now for doors!

And perhaps videos..?       :emoji_u1f601:

(https://media.giphy.com/media/WUEJFVkjszmIU/giphy.gif)
Title: Re: DE (Cabin Mod) tail Modifications
Post by: MrG on July 11, 2019, 12:48:10 AM
Cold and good time to chop up the fuse  - getting there
Title: Re: DE (Cabin Mod) tail Modifications
Post by: azevedoflyer on November 04, 2019, 04:51:04 PM
rfeenstra,
Just getting started in a DE.
Your "baby" Aeronca, just like the Australian relative,look awesome!
A little tardy but never too late, congrats!
Have you posted an in-flight comparison before&after mods?
Cheers,
azevedoflyer
Piper PA22/20-150
DE to incorporate tail mod.
Title: Re: DE (Cabin Mod) tail Modifications
Post by: rfeenstra on November 05, 2019, 07:47:23 PM
If you go back through the thread, you'll find a few comments on the new flying characteristics.  Flew it a fair amount this summer and really enjoy it.  I have one fuel tank that's leaking a tiny bit so i'll have to remove that this winter to deal with it.  Otherwise, doing great!
Title: Re: DE (Cabin Mod) tail Modifications
Post by: azevedoflyer on November 05, 2019, 08:35:43 PM
 :) That's seals it!
Will extend the fuse as well. 21" you said?
thanks,
Miguel
Title: Re: DE (Cabin Mod) tail Modifications
Post by: rfeenstra on November 06, 2019, 07:38:06 AM
No, 26".  but remember, my wingspan is about 32" greater than plans because of the cabin.
Title: Re: DE (Cabin Mod) tail Modifications
Post by: azevedoflyer on November 06, 2019, 07:42:18 PM
Chief Eagle,
Excellent work!
A question to you: when you started building the DE, did you have access to an inventory of tubing necessary (diameters / thicknesses / total length etc)?
Just bought DE plans and nowhere can I find such info...
How did you solve this initial hurdle?
Just retired and moved from Ann Arbor to Trion GA.Need to start building before I go crazy...
Thanks,
azevedoflyer :)
Title: Re: DE (Cabin Mod) tail Modifications
Post by: MrG on November 06, 2019, 07:56:15 PM
i have to order some more Molly i can email some images of mine with sizes I've used for the tubes - why im working out what i need 
Ive really closely copied an Aronica that is local to get all my measurements for the back of the cabin to the tail
Title: Re: DE (Cabin Mod) tail Modifications
Post by: azevedoflyer on November 06, 2019, 08:25:47 PM
MrG: greatly appreciated your help!
Looking forward to your post.
azevedoflyer
Title: Re: DE (Cabin Mod) tail Modifications
Post by: rfeenstra on November 06, 2019, 10:02:26 PM
I had initially ordered as per the parts list but needed to increase a few things later.  As far as the new tail is concerned, I ordered a whole supply of tubing  as I was also working on the Champion that was the model for the tail.  so far, I haven't used any of the tubing other than what I needed for the new tail as work on the Champion stopped for an indefinite period of time!