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Indoor Free Flight Forum => Bostonian => Topic started by: Yak 52 on February 03, 2012, 09:10:32 AM



Title: Bostonian Bede BD5
Post by: Yak 52 on February 03, 2012, 09:10:32 AM
Hi all.

This is my Character Bostonian design, based on the Bede BD5 pusher jet. I've finished drawing the plan and started cutting wood so I thought a build thread might be realistic. Once I've built it (from photocopies) the plan will be finalized then scanned to pdf and anotated.

The BD5 is a cool little plane! This version is stretched and squashed and simplified to fit the Bostonian rules. As a model it has a few interesting features, a short tail means trimming might be tricky but also makes room for a 13" long motor... we'll see I guess.

At some point I'll be looking for advice on making a pusher prop...


Cheers!
Jon


Title: Re: Bostonian Bede BD5
Post by: tross on February 04, 2012, 09:04:32 AM
Nice Jon,
Interesting choice.
I remember driving with my dad to Oskosh back in the early 70s, we did that a couple of times.
He was disapointed that the thing didn't quite make it.
He was building one of his experimental planes and was talking most of the way up about how he was going to get one of those next.
He didn't. He bought a 1948 Piper Vagabond instead!!
I was wondering about the thrust line. I'm thinking you have that covered and I was just curious.
Won't the plane pitch up as the power is reduced? Or are you thinking outside the box.
You know how I love that.

Tony


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 04, 2012, 09:45:01 AM
I'm planning to suck it and see! I'm hoping that with a generous amount of stability (forward CG) the tendency to power stall will be countering the high thrustline/downthrust effect. I've just set the thrustline to the datum and I'll add shims as neccesary.

So rather than pitch up as power is reduced, I'm giving it something to pitch down against power on... if you get me?

I'm far from "having it covered" though so I'd welcome thoughts, advice, counselling  ;D

Tobgun did a scale version which trimmed out nicely in the end so I'm optimistic  :)


Title: Re: Bostonian Bede BD5
Post by: tross on February 04, 2012, 09:51:44 AM
Quote
So rather than pitch up as power is reduced, I'm giving it something to pitch down against power on... if you get me?

I get you. You're working the other end.
Balanced with power down, giving something to push against at power up. So it doesn't pitch down at thrust.
It'll be way cool. Can't wait.

Tony


Title: Re: Bostonian Bede BD5
Post by: Hepcat on February 04, 2012, 04:02:58 PM
Jon
Very cleverly done to get the character so well into a miniature slabsider.  Like you I would worry about the moment arm - would anyone notice if you moved the wing forward a smidgen, or even a tad? 

The drawing looks good.  Is that with your new CAD software?  And what about the pictorial view?  I notice that you treat your Warren girder joints differently on the tailplane to those on the fuselage and the fin.  Am I missing some fine nuance of design here or did you just feel like being different!

John


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 04, 2012, 06:52:41 PM
Thank you very much John  :)

I seriously considered moving the wing forward but my fear of phugoids was overcome by my fear of nose weight!  :-\ I could just see all the weight piling on at the back with the prop assembly etc and decided to put as much of the motor forward of the CG as I dared. I probably overdid it on the forward structure for the same reason. The tail volume is still reasonable (about 0.8 as I recall) and I'm hoping to get some extra stability from the pusher prop. I hope the risk pays off, if I can get it to fly then the 13" motor space should come into it's own.

The plan is drawn by hand (drawing board, french curves etc), I've put my CAD on hold for the moment. I'm getting somewhere with it but it takes me forever to do the simplist things! I'm actually quicker on the drawing board despite numerous drafts. When I've finalized it I'll scan it and annotate it on the computer. The pictorial view is just an early stage isometric projection with a few sketchy bits thrown in. I do that now and then to help me visualize it.

The warren girder joints weren't particularly nuanced  ;D I did give some thought to where the stresses might come from but mostly I was thinking of what was simplest to build, as in "which bit will be pinned down first and which bit will I be cutting." I'm sure there is a 'proper' way though? The warren trusses just seemed to fall into place with the fuselage, in terms of what fixed points I had. The fin came next and with the sweep it had to be 'warrened' ( ???) then the tailplane really had to follow suit. I thought it made it look a bit more modern and funky although I'm sure it's overbuilt...

I plan to use the angle of the nosegear to perfect the right attitude for ROG.


Thanks for the interest... I'll be hoping to pick your brains on the prop soon  8)

Jon


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 06, 2012, 08:16:10 AM
Construction has begun...

The sides came together ok, the bent longerons were soaked to get them to hold the bend better. I've added a couple of gussets around the bit where the fuselage 'splits', it seemed a bit vulnerable when the lower bit is bent. And of course I just moved the stresses elsewhere  :-\


Jon


Title: Re: Bostonian Bede BD5
Post by: danmellor on February 06, 2012, 02:49:41 PM
Superb! Yet another for the ever growing "to do" list... Sigh.


Title: Re: Bostonian Bede BD5
Post by: Pete Fardell on February 06, 2012, 03:17:34 PM
Jon
Very cleverly done to get the character so well into a miniature slabsider.  Like you I would worry about the moment arm - would anyone notice if you moved the wing forward a smidgen, or even a tad? 
I can never quite remember; exactly how many smidgens are there to a tad?
Pete


Title: Re: Bostonian Bede BD5
Post by: Hepcat on February 06, 2012, 05:33:43 PM
Pete
I am not surprised you can't remember, it's one of those unusual ones three and a half Smidgens to the Tad.  Then of course there are the subdivisions of the Smidgen the Gnats Dickie and the Hole Down its Middle but these are usually taken as variable and appropriate to the particular job.
John


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 06, 2012, 05:52:37 PM
Thanks Dan  :)

John, thanks for that - I always have trouble converting from 'bodgic' to metric.
I'd heard of the gnat's crotchet as a measurement of time but a gnats dickie was new to me  ;D


Jon


Title: Re: Bostonian Bede BD5
Post by: OZPAF on February 06, 2012, 06:18:37 PM
That looks like an interesting challenge Jon.


I seriously considered moving the wing forward but my fear of phugoids was overcome by my fear of nose weight!  :-\ I could just see all the weight piling on at the back with the prop assembly etc and decided to put as much of the motor forward of the CG as I dared. I probably overdid it on the forward structure for the same reason. The tail volume is still reasonable (about 0.8 as I recall) and I'm hoping to get some extra stability from the pusher prop. I hope the risk pays off, if I can get it to fly then the 13" motor space should come into it's own.
Jon

It may help when visualising pushers to treat the nose length as what you would have expected to see if it was the tail boom length, and then the tail length on the pusher will then to a degree resemble the nose length. It's only meant to be a quick cross check and obviously tail volumes and static margins still need to be sufficient.
It can be surprising how long the nose may need to be and this approach helps to put your mind at rest.
Those definitions stir some memories John – although I had never heard of the sub divisions of a smidgeon. I don’t think I worked to that level of accuracy. ;D
How did the system allow for angles - flickers of the gnat’s wing or similar?  ;D
John



Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 07, 2012, 06:41:49 AM
It may help when visualising pushers to treat the nose length as what you would have expected to see if it was the tail boom length, and then the tail length on the pusher will then to a degree resemble the nose length. It's only meant to be a quick cross check and obviously tail volumes and static margins still need to be sufficient.
It can be surprising how long the nose may need to be and this approach helps to put your mind at rest.

Hi John, not quite with you there, are you talking about the yaw damping effect of the forward fuselage? Or are we talking weight distribution of the motor/prop set up?

Plugging away with the build. Tail surfaces are done, weight of the tailplane was 0.6g and the fin 0.4g. The tailplane will have the TE spar slot cut out when I've covered it. It then slots into the fuselage and is pushed back into position. Then the slot is filled again with a small piece of sheet and patch covered.

The fuselage is jigged up on it's back (the only flat bit). Looks like a beetle...

I'm finding all the structures so far have come out nice and stiff so really light balsa could be used.


Jon


Title: Re: Bostonian Bede BD5
Post by: Pete Fardell on February 07, 2012, 07:12:39 AM
That's a very technical looking jig, Jon. Did it take a lot of building and wherever did you source the parts for it? ;D


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 07, 2012, 07:20:28 AM
It was custom built Pete...  ;D

Investment was made over a long period. Finding storage space for jig materials has been problematic. The management felt we should declutter but the shopfloor union made a pressing case.


Title: Re: Bostonian Bede BD5
Post by: OZPAF on February 07, 2012, 06:22:40 PM
It may help when visualising pushers to treat the nose length as what you would have expected to see if it was the tail boom length, and then the tail length on the pusher will then to a degree resemble the nose length. It's only meant to be a quick cross check and obviously tail volumes and static margins still need to be sufficient.
It can be surprising how long the nose may need to be and this approach helps to put your mind at rest.

Hi John, not quite with you there, are you talking about the yaw damping effect of the forward fuselage? Or are we talking weight distribution of the motor/prop set up?

It’s more of a rough check on the overall weight distribution Jon. When you consider how a conventional layout with its tail moment will in most cases come close to balancing as required - it helps to use something close to this length in a pusher.
Thus I found your layout to be close to what I would have expected in terms of wing position and nose length.

As your BD5 has a flat sided fuselage this nose length may reduce your yaw stability and require a larger fin although the prop is helping here as you mentioned.

I still envious of all those nice tight joints and your that high budget building jig. ;D

John


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 08, 2012, 05:18:10 AM
Thanks John, yeah it was always going to be a compromise between nose length for weight distribution and the tail moment arm for stability. The one positive about the long nose is that it should make for more spiral stability providing I get the fin area right. I was planning for 1" to 1.25" dihedral under the wing tip. (That's a wadge or a wadge and a tad btw) In fact I have to have a certain minimum dihedral because the flat wingspan is 16 1/8" so that the projected span will be 16".

The fuselage is coming along. It just needs a nose block and some of the structure on the rear end to complete. I soaked the lower rear fuselage and rolled it under a pen to get it to take the tighter curve. It was a bit tricky and I should have used lighter/softer balsa in that area. The fuse weighs 2.75g at this point.


Thanks for the interest,

Jon


Title: Re: Bostonian Bede BD5
Post by: OZPAF on February 08, 2012, 05:36:22 PM
You've solved the mystery, Jon ;D Angles are measured in wadges!
How is the torsional stiffness of the fuselage just in front of the prop Jon? It is reduced cross section and the prop shaft tunnel doesn't seem to have spacers on the bottom?
Fast work.
John


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 08, 2012, 06:17:13 PM
How is the torsional stiffness of the fuselage just in front of the prop Jon? It is reduced cross section and the prop shaft tunnel doesn't seem to have spacers on the bottom?

It will have! It will fair into the lower fuselage with something approaching a wing fillet, which includes a former and partial keel yet to be fitted. The stiffness overall is pretty good - I could have gone a lot lighter on the wood  :-\


Jon


Title: Re: Bostonian Bede BD5
Post by: Sky9pilot on February 08, 2012, 08:04:43 PM
Yak52

Love the BD5, been following this over at SFA...nice progress.  Look forward to seeing this one in the air...great work.

Tom


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 09, 2012, 06:38:38 PM
Thanks Tom, you settling in ok?


I thought the fin mounting might be worth a bit more detail. It's actually just slotted into two pieces of 1/16th strip but I use the 'jig' to set it up correctly.

First off I cut the two strips to the right length as measured against the gap between the relevant cross pieces on the actual fuselage. Having done this they are pinned to the plan in the correct position laterally, using another strip as a spacer.

Then the fuselage goes back in the jig, aligned over the plan again. Having tested the fit and got the position right it's lifted off, glued up and then re jigged.

This puts the slot in the centre and hopefully aligns it correctly. I might add a strip under the forward end to protect the tissue, if I can afford the weight...


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 10, 2012, 09:01:22 AM
The partial keel is attached to the rear former and the lower fuselage.


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 11, 2012, 05:59:59 AM
The final bit for the rear fuselage is the small former. I'm hoping I can tissue cover the curved concave bit without wrinkles, but I may have to use a bit of stiff paper like you would for a wing fillet.

The result is that the motor part of the rear fuselage is reasonably stiff in torsion despite the small cross section. The partial keel piece was cut from quarter grain balsa which seems to help a bit too.

With the little scallop the motor has a clear run to the peg at the front. There's not loads of room inside at the back but hopefully enough.


Title: Re: Bostonian Bede BD5
Post by: tross on February 11, 2012, 07:57:23 AM
Looking good Jon.
By all means, I would give it a go.
But if the compound curves start to give you fits, you might try a straight contour at the last former installed and
a small amount of stiff paper at the transition.

Tony


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 13, 2012, 06:24:18 AM
If I've got it right there should be no compound curve there, just a 'cone'. It's just that with plain tissue it may wrinkle a bit. I was thinking on similar lines but going the whole hog and making the keel bit a straight line from the lower fuselage to the rear former. It would be a lot simpler (more Bostonian?) but this way is working so far....


Title: Re: Bostonian Bede BD5
Post by: Sky9pilot on February 13, 2012, 12:32:16 PM
Yak52,

The BD5 is progressing nicely.  I am definitely going to have to build one....I'm in Texarkana, TX now and am getting settled.  No building space yet, but soon.  Snowed last night so the ground and bushes are covered in snow...just a couple of inches.  Not suppose to last.  For a guy from California it's a bit cold :o ::) :P  Definitely building season here! ;)

Tom


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 14, 2012, 12:52:19 PM
Glad you're getting sorted Tom.

The wing on the BD5 is largely self-explanatory. The dihedral is 1" per side and the root ribs are at an angle set by the dihedral templeate. The spars and LE are cracked and glued and the TE is notched to accept the ribs. The spars are only glued in on the second side once the dihedral is set up.

Weight of the wing is 1.57g.


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 14, 2012, 12:59:53 PM
The nose block is laminated from 3 sheets of 3/16". In actual fact I used two light pieces of 1/4" capped with some hard 1/16 sheet, which should be a bit tougher for when it clobbers the wall  :-\

The wheels are laminated from two sheets of 3/32" and cut with my olfa compass cutter. I couldn't get on with this at first but I've finally sussed out how to use it. I found the point just ripping along the grain and ending up with big ovals. I now layer a few bits of masking tape to stick the point through (the disk that comes with it wasn't much help.) And then it's just a case of not cutting too hard and doing lots of turns. And turning it with the top bit between finger and thumb for minimum torque at the pointy end.

The wheels aren't finished yet: at some point I'll turn them on a power drill...


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 14, 2012, 01:03:37 PM
The wire was bent for the UC... which meant it was time for a few bones shots  :)


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 14, 2012, 01:07:02 PM
And a few close ups...

It still needs a few details finishing (wheels and UC fittings) but the weight so far is 8.2g, 2g of which is the UC wire. It's going to be tight to hit 14g with the large windows, prop and covering... The CG is currently about 50-60%.


Title: Re: Bostonian Bede BD5
Post by: Sky9pilot on February 14, 2012, 01:54:15 PM
Jon,

Loved the additional pics here...looking terrific...can't wait to see it with "skin" on... ;D 8)

Tom


Title: Re: Bostonian Bede BD5
Post by: FreeFlightModeller on February 14, 2012, 02:44:52 PM
Very tidy build Jon  :)

Hope to see it at Impington?



Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 14, 2012, 03:41:32 PM
Thanks Tom!

Hope so Russ! Got to finish it first...  ;D
You planning to be there?


Title: Re: Bostonian Bede BD5
Post by: FreeFlightModeller on February 14, 2012, 03:58:55 PM
Jon,

Last October was the first Impington I've missed in years ... hopefully I will not miss another!
Have you been there before? I am usually late to any meeting that starts in the morning, but it is best to get there early ... a very popular meeting if you haven't been before.
I need a new Bostonian for the event . Whether I will get the chance though ......


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 14, 2012, 06:07:46 PM
No, it'll be my first time :) What about a Gyminnie Cricket?  ;D


Title: Re: Bostonian Bede BD5
Post by: FreeFlightModeller on February 14, 2012, 07:16:06 PM
It would have to be a new Gyminnie Cricket ... my old one got very tatty very quickly.
I covered it in my shed thinking it was reasonably dry .... but when I got it to a Nottingham Indoor the tissues started shrinking that much I had to cut it to stop damage!
I re-covered the wing at the meeting and got it flying reasonably, but it looks a bit of a mess.
I think I still have another kit for the Cricket so I might just get one ready. It would have to be trimmed for tighter circles than my last one though ... Impington is only about 50' wide, but with tables all around the perimeter. Always be prepared for a little 'carnage' at Impington!


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 15, 2012, 04:13:18 PM
Well I've started to think about the prop  :o

I'd welcome any input or experience. I'm trying to decide which way to make it turn. In some ways anticlockwise (looking forwards) would be convenient as I usually wind clockwise. I'm not sure if that makes it right or left handed with a pusher? ???

I'm also wondering about 'torque' effects? I'd imagine that the above set up would induce a right turn. Although there should be less effect from the helical swirl of the slipstream over the fuselage and fin on a pusher?

I'm prepared to try it and make adjustments but I'd like to work it out too if possible. For one reason, I intend to build in washin into the inner wing, so making it turn predictably is important.


Jon


Title: Re: Bostonian Bede BD5
Post by: OZPAF on February 15, 2012, 06:07:05 PM
Thats a really nice  set of bones, Jon. I'm waiting almost patiently for the skin and glazing.  It's not every day you see a nice little pusher.
I would think that it is probably best to choose the propeller rotation to suit your winding methods/winder, and then trim the model to suit. I can't imagine either direction having an advantage for trim, over the other.
Would Gurney flaps on the wing be better than built in wash in Jon as the best turn direction under power is still in question?
I think I would favour turning against the torque - but this may require far too much side thrust and I don't have enough experience in this area.
John


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 17, 2012, 06:37:39 AM
Thanks John. I think I've now established that a left-handed pusher prop (anti-clockwise looking forward) will want to yaw the nose right due to 'P' effect and torque will make it drop the right wing. So it should be the opposite effect of a standard right-handed tractor prop.

I think the idea of trim tabs is probably wise  ;D

I've flown both with and against the torque outside but I've had a bit of success flying left hand circuits indoor - ie with the torque. I think this is normal but I'm not sure of the sidethrust other people use indoors? The problem is what happens as the motor runs down and the prop effects drop off - the model either opens up the circle and clobbers the wall or drops the inner wing. Not sure what the best way of dealing with this is yet... I'm a bit of an indoor rookie...


Jon


Title: Re: Bostonian Bede BD5
Post by: FreeFlightModeller on February 19, 2012, 04:34:29 PM
Good to meet you on Saturday Jon  :)

Looking forward to seeing the Bede ... I'm sure it will be a super crisp build like the models you had with you at the weekend.



Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 19, 2012, 04:36:53 PM
Likewise Russ! And I never got to say congrats on your win  ;D


Title: Re: Bostonian Bede BD5
Post by: lplanetta on March 20, 2012, 12:10:10 PM
Yak52, what great work on your BD5.  The BD5 has always been one of my favs.  Any possibility of getting a copy of your plans to build my own?



Title: Re: Bostonian Bede BD5
Post by: Yak 52 on March 21, 2012, 06:26:08 AM
Hi, sure no problem. I'm planning to annotate/adjust it and scan it once I'm happy with the prototype, then I'll upload it to the plans gallery at some point.


Title: Re: Bostonian Bede BD5
Post by: TimH on March 21, 2012, 10:33:26 PM
Quote
I never got to say congrats on your win 

Sorry for the thread hijack Jon, but we need details. What did Russ win? What time did he manage? The public want to know ;D

Tim ;)


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on March 22, 2012, 08:56:01 AM
He won the Gyminie Crickets at Bushfield, 1 minute 10 if I recall correctly  ;D


Title: Re: Bostonian Bede BD5
Post by: TimH on March 22, 2012, 04:51:21 PM
Well done Russ  ;D ;D ;D


Title: Re: Bostonian Bede BD5
Post by: FreeFlightModeller on April 01, 2012, 06:47:23 PM
A late thank you Jon and Tim ... I only scraped away from the chasing pack by a second to be honest. This pack included juniors and a FF novice ... I think this was better to see than my cricket juddering it's unbalanced way around the room! I got the same performance at the small hall at Impington too, but this time I was relegated to about mid field. I think one model comps are good for testing your methods ... there was another today at Nottingham for Hanger Rats ... but I won't take up you thread any more Jon (I will be posting a few shots soon elsewhere I hope)


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on April 14, 2012, 06:10:05 AM
I've remade the undercarriage from 22 SWG wire - the previous one was 20 SWG and was a bit overkill. It also didn't fit in the tube hubs of the wheels Id made  :D I've now found the perfect combo of 22 guage wire and alloy tube. The fit is slightly loose but they spin nicely.

The wheels are light balsa and weigh 0.25g each. The new wire UC weighs 0.83g as opposed to the previous one's 1.21g. The whole lot weighs 1.6g. I'm just deciding whether to glue the UC into the nose and wing before covering or whether I should create the slots and CA them in afterwards...

The plan is to adjust the angle in the nosegear to set the right attitude for ROG.


Jon


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on April 17, 2012, 07:43:35 AM
I've been doing lots of fiddly bits and bobs, adding gussets to the wing, building the slots that take the undercarriage wires, sealing and sanding...

The UC slots in and is removeable. It's a tightish fit but I will likely bleed in some CA when it's flown and trimmed out. The pins holding the slot open while gluing are just abit thinner than the wire so the fit is secure. Clearance for the prop is half an inch (at rest) so I'll probably need to bend the main gear wires down to increase this for ROG, depending on how it behaves.

I've also added some small 1/32 strip doublers to the inside of the fuselage. This was a weak spot where any pressure tended to crack the glue joints either side of the main longeron. It's now much stiffer.


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on April 17, 2012, 09:08:20 AM
Anyway, I now have the woody bits virtually finished and I'm about to start covering... so here's an 'official' bones shot or two... The weight is now 8.1g after sanding, sealing and the new UC.


Title: Re: Bostonian Bede BD5
Post by: Sky9pilot on April 17, 2012, 01:20:22 PM
Good looking bones...can't wait to see this baby finished...

Tom


Title: Re: Bostonian Bede BD5
Post by: atesus on April 17, 2012, 02:06:32 PM
Very pleasant lines 8). Looks like you'll be right around 14g too.


Title: Re: Bostonian Bede BD5
Post by: OZPAF on April 17, 2012, 09:22:17 PM
Very nice Jon and it has captured the Bede BD5 charm.
John


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on April 21, 2012, 08:08:46 AM
Thanks guys.

I started covering earlier this week: I did the nose block first (covered wet) and then did the sides - completely forgetting my plan to do the 'fillets' at the back first  :-\ So I took all the sides off again and did the fillets. As it's a conical curve, they are a single thickness of tissue. They'd be better with a bit of paper like a wing fillet, but it's the wrong place to be adding weight.

I've been experimenting with floral spray to improve the colour of the tissue trim. I'm having some problems with the paint bleeding through however. But it's still a lot better than straight tissue which just disappears on the dark blue. In the pic below they all look better than they are because of the white paper they are laid on.


Jon


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on April 21, 2012, 10:02:16 AM
Fillets are done! I'm pleased at how easy they were with just tissue. The trick was getting the grain and tension lengthwise down the cone of the curve (as shown on the pic.) While I was building the half former had been sanded to conform to this cone with sandpaper wrapped around a pen of the right radius.


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on April 21, 2012, 10:03:47 AM
I was asked elsewhere about the clearance for the motor at the back. What might not be obvious is that the fuselage is entirely open until you get to the tail's leading edge and the small half former. The pics show a blast tube placed inside.

The motor is slightly angled relative to the propshaft but I'm hoping this will be ok with a long, low-powered indoor motor?


Title: Re: Bostonian Bede BD5
Post by: lincoln on April 21, 2012, 09:38:44 PM
I don't think the angle should be a problem. I've seen a design for a twin that had both motors angle from the back of the prop assembly to the centerline of the fuselage! (Astral kit for Briston Blenheim, in the Plan Gallery)

People I know use chalk pastel on the back of their tissue when they want it to look more opaque or to change its color.

Also, I wonder what it looks like if you spray a very light coat of silver on the back of the trim pieces before applying?


Title: Re: Bostonian Bede BD5
Post by: DaddyO on April 22, 2012, 03:12:37 AM
Hiya Yak52 . . . .lovin' it so far  :D

I always give the back of the printed tissue a light spray of white acrylic from a rattle can if it's going onto a dark surface (Stick it on with a UHU gluestick) which doesn't add a lot of weight and make's one heck of a difference.

Cheers
Paul


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on April 22, 2012, 05:17:53 AM
Thanks chaps. The floral spray works well but the bleed problem is more because of the tissue - the red is peck and the orange domestic. I chose them for the vibrant colour (better than esaki) but the weave is quite open. I'm getting there with the spray though. Building up thin coats one at a time seems to be working ok. I've never had much success with chalking tissue but I'll do another test strip and see how it goes...


Title: Re: Bostonian Bede BD5
Post by: Hepcat on April 22, 2012, 06:41:49 AM
I admire your workmanship and I have added a kudos for the fillets - you must be proud of those.

John


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on April 22, 2012, 11:40:50 AM
Thank you John  :)


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on April 23, 2012, 08:09:24 AM
Covering the fuselage continues.

The correct sequence seems to be nose block (covered wet) and 'fillets' first. Then the sides, then the top and bottom. The side pieces can be cut out over the plan to make trimming easier around the rear end.


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on April 23, 2012, 08:10:40 AM
The fuse is now 4.3g, so covering has added less than a gram.


Title: Re: Bostonian Bede BD5
Post by: Sky9pilot on April 23, 2012, 10:04:01 AM
Jon,

Inspiring job of covering....very nicely done...

Great model

Tom


Title: Re: Bostonian Bede BD5
Post by: OZPAF on April 24, 2012, 10:58:51 PM
I was sure you would have had problems with the rear fillets Jon. I'm glad I was totally wrong. Outstanding work on this model.
John


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on May 05, 2012, 08:00:35 AM
Covering is now complete - I had to wait quite a while because of the hideous weather we've been having  :o

I used dope on the fuselage but banana oil on the wings and tail surfaces. The banana oil works really well and has a nice finish. It does seem to shrink much either.

Weight is now up to 10.5 grams - canopy, prop and colour trims to add. It will also need some noseweight (the CG is just forward of the main gear now but most of the extra weight will go aft of this point) so I expect to go over the 14g air frame target.

The nose block was accidentally covered in a different batch of esaki - I had to order some more for the wings and tail. I ought to re-do the nose but it's too much trouble  :-\ Lesson learned though...


Title: Re: Bostonian Bede BD5
Post by: danmellor on May 05, 2012, 10:54:51 AM
Lovely! Got to have a go at this one when you post the plan...

Dan.


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on May 06, 2012, 11:58:06 AM
Thanks Dan, (and Tom and John from posts #63 and #64)

I have a few tweaks to make to the plan and then I'll scan it. I'd be chuffed to bits if anyone has a pop at it  8)


Jon


Title: Re: Bostonian Bede BD5
Post by: danmellor on May 06, 2012, 12:47:49 PM
Like I said, I gotta build this one! Thinking about it, I have three pushers sat around in their boxes.. Seems to be a weakness of mine! Along with violent thrash metal and senseless alcohol abuse....

Dan.


Title: Re: Bostonian Bede BD5
Post by: rgroener on May 07, 2012, 06:43:07 AM
Jon, your BD5 is coming out great! I hope you have already ordered good weather and a nice soft field for test flights. It's not far anymore.
Good luck and dont forget to take pictures or even a video :D

Best regards Roman


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on May 14, 2012, 07:08:15 PM
Thanks Roman, glides over the bed seem good so far. Glide ratio is better than expected (missed the bed!  :o) but no damage fortunately...


Title: Re: Bostonian Bede BD5
Post by: Snow Owl on July 05, 2012, 09:56:35 PM
Thanks Dan, (and Tom and John from posts #63 and #64)

I have a few tweaks to make to the plan and then I'll scan it. I'd be chuffed to bits if anyone has a pop at it  8)


Jon
Have you scanned it yet? I'd love to have the plan. It really looks like it would be a lot of fun to try to build it.

Have you flown it ? How did it go?


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on July 06, 2012, 06:13:22 AM
Hi Snow Owl,

I have struggled to scan the plan with my A4 scanner, it keeps distorting slightly  :-\ so I will have to go to a copy shop or something and do it fullsize. The model isn't quite finished yet (I lost impetus when the SFA cook up finished) but it's on my to do list  :) Test glides are quite encouraging, with a flat glide for a bostonian (low drag hopefully). It just needs a prop, the canopy and a few trim stripes...

Jon


Title: Re: Bostonian Bede BD5
Post by: Snow Owl on September 13, 2012, 12:55:26 PM
Hi Snow Owl,

I have struggled to scan the plan with my A4 scanner, it keeps distorting slightly  :-\ so I will have to go to a copy shop or something and do it fullsize. The model isn't quite finished yet (I lost impetus when the SFA cook up finished) but it's on my to do list  :) Test glides are quite encouraging, with a flat glide for a bostonian (low drag hopefully). It just needs a prop, the canopy and a few trim stripes...

Jon

What's the latest on your BD -5? Have you flown it? Did you ever manage to scan the plans? If you only have a full-size paper copy, could I give you some money for a copy?


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on September 14, 2012, 04:40:08 PM
Hi Snow Owl, thanks again for the interest, not done much with it yet but the incentive is there as we have now got some indoor dates to spur me on... I go the bits out and have bumped it up my build list. I still hope to annotate and scan the plan, but I will have to make a couple of tweaks first.

Cheers
Jon


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on October 10, 2012, 11:20:20 AM
Making some progress with the trims. I went for red and orange esaki backed with white floral spray (two light coats) It seems to have kept the colour nice and bright. The strips are stuck on with glue stick because dope/cellulose thinners melts the floral spray :( Hope to get it done for the next Impington at the end of the month  :-\


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on October 10, 2012, 04:57:14 PM
Well the trims are complete. I'm quite pleased at how slimming the stripes are  ;D it looks less Bostonian and a bit more jet-like. I'll take some better pics in daylight tomorrow. I have some laminated prop blades drying in the airing cupboard now too :)


Title: Re: Bostonian Bede BD5
Post by: Sky9pilot on October 10, 2012, 06:34:30 PM
She's a Beaut!

Love the trim stripes.  Very well done and really sets off the scheme!

Tom


Title: Re: Bostonian Bede BD5
Post by: OZPAF on October 10, 2012, 08:20:21 PM
I agree with Tom. The coloured stripes really bring that model to life.
That wouldn't be some proposed sketches for a bungee tow launch glider in the background of one of the pics ?
John


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on October 11, 2012, 07:29:18 AM
Thanks Tom, John.

Yep, I've been doodling again John. Can't decide on quite which way to go... It's an interesting task with the restricted wing span.


Jon


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on October 16, 2012, 05:46:07 PM
I've been working on the laminated pusher prop. It's 'reversed' so that it is wound in the same way as a tractor, rather than having to think about which way I should be winding it  :D

The blades are laminated from thinned 1/32nd sheet, moulded at a 15 degree angle on a 2.5" diameter spray can. The airfoil was sanded in, then the blades were attached to the bamboo in a jig. Then it was covered in black and yellow esaki. There will have to be a small cut away to clear the tail block.

The final weight is 0.8 grams, which I'm pleased with, especially considering it's in the wrong place  ::)

The blade angle at the 75% radius point is 30 degrees which gives it a Pitch/Diameter of about 1.3 (and a bit). Some predictions from Prop Picker are quite encouraging:

Motor space:             12.75"
Motor length at 1.5x:  19.2"
Motor:                       2 strands of 1/8th
Turns:                       2100
Motor run:                 82 seconds
T/TO:                       2           (intial thrust ratio)


Title: Re: Bostonian Bede BD5
Post by: OZPAF on October 17, 2012, 01:25:58 AM
That looks interesting Jon.! Hope you have a test flight window in the weather soon.
John


Title: Re: Bostonian Bede BD5
Post by: Andrew Darby on October 18, 2012, 04:27:45 PM
Lovely job Jon, the prop is a real work of art.

I can scan your plan full size if you need......

Andrew


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on October 18, 2012, 05:01:56 PM
Andrew, that would be extremely kind, thank you! I have some adjustments to do first but I may well take you up on that, logistics permitting.

Cheers
Jon


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on October 25, 2012, 12:09:25 PM
Not far now: Final weight of all the components before assembly is 12.8g. Just got to stick it all together and attach the prop...

Jon


Title: Re: Bostonian Bede BD5
Post by: dosco on October 25, 2012, 03:01:54 PM
Very tasty. Well done.

Hope to see some in-flight pics soon!


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on October 27, 2012, 08:37:28 AM
Thanks dosco.

Pretty much done now... needed about 3g of noseweight to bring the CG to the calculated position. Test glides indoors have been a bit inconclusive but it seems about right. Too wing to glide it outside today.

I have extended the UC to give a bit more prop clearance (that's what the bends were for!) The UC is nice and springy but the rear gear is close to the CG and when the nosewheel hit's first iyt bounces and causes the model to pitch nose up, especially in a heavy landing. I hope it'll be ok in a steady glide at the end of a flight indoors. I can play around with the UC heights to perfect the rotation and ROG.


Jon


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on October 27, 2012, 08:43:22 AM
A few more pics...


Title: Re: Bostonian Bede BD5
Post by: Laurence Marks on October 27, 2012, 11:03:51 AM
That is a fantastic looking model.  Would love to see some flying shots.  As if there aren't enough projects on the to-do list...


Title: Re: Bostonian Bede BD5
Post by: Dave Andreski on October 27, 2012, 11:17:53 AM
Jon,
VERY NICE, CLEAN build!
Dave Andreski


Title: Re: Bostonian Bede BD5
Post by: DaddyO on October 27, 2012, 11:29:45 AM
Lovely work sir - can't wait to see the plan . . .


Title: Re: Bostonian Bede BD5
Post by: danmellor on October 27, 2012, 11:33:53 AM
Me too! Gorgeous model...


Title: Re: Bostonian Bede BD5
Post by: atesus on October 27, 2012, 04:04:05 PM
Looks very cool, and very nicely built! Looking forward to flight reports.

--Ates


Title: Re: Bostonian Bede BD5
Post by: RolandD6 on October 27, 2012, 05:20:15 PM
A very nice looking model Jon. As others have already said, the trim stripes do add to the appearance of the model and I love the delicate look of the whole scheme.

I hope you are rewarded with good flying characteristics that compliment the good looks.

Paul


Title: Re: Bostonian Bede BD5
Post by: Mr Blue Sky on October 28, 2012, 04:07:50 PM
Hello John,
It was nice to meet you, albeit briefly, at Impington today. The Bede looked superb, such a pity about the leading
edge dings. I hope the repairs aren't too troublesome. Your Cub is very smart and looks very good in the air. I gave
a copy of the Cub plan to a mate who wasn't too keen about it but after seeing yours he went home to start
cutting wood. I hope your journey home was OK, I had heard there was trouble on the 14 but it had probably
cleared by late afternoon. I hope to see you again in March 2013.

Bye for now,

Tony.


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on October 28, 2012, 06:04:52 PM
Thanks everyone for the kind comments. Tony, it was nice to meet you too. The dings will polish out  ::) I think outdoor trimming when it's repaired though! My mate Phil did manage to video the single half (quarter  :-\) decent flight. I think I hadn't got enough rubber in it so it just skooted along the floor too far before rotating. Hopefully I'll get it into circling trim from a hand launch and then work on the ROG.

Jon


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on October 30, 2012, 10:07:18 AM
Well, here's the best 'flight' on video, plus a couple of proper pics from Phil. The damage can be repaired easily enough but maybe a tougher LE would have been better.

On reflection I think I was a bit ambitious trying to trim it at Impington. The model seemed quite keen to leave via the fire exit...

http://www.youtube.com/watch?v=4UkATJ0sGf4&noredirect=1 (http://www.youtube.com/watch?v=4UkATJ0sGf4&noredirect=1)


Title: Re: Bostonian Bede BD5
Post by: tross on October 30, 2012, 12:56:27 PM
I was going to press the "like" button.........
because I really really liked it.....
But, then there was that bit at the end that.....if I gave it a 'like' you might think I liked that part.
Can we have them move the fire exit door to the wall on the right? :D

Tony


Title: Re: Bostonian Bede BD5
Post by: danmellor on October 30, 2012, 01:20:16 PM
You are a brave man to try trimming at Impington! Lovely meetings but a tad on the small side for a new model. Looked good, though!

Cheers,

Dan.


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on October 30, 2012, 01:56:33 PM
Cheers Dan.

But, then there was that bit at the end that.....if I gave it a 'like' you might think I liked that part....

Ha ha, I thought that was the best bit  ;D Saved the prop nicely. In fact I'd vote for a nice rail all the way round the hall  ::)


Title: Re: Bostonian Bede BD5
Post by: atesus on October 30, 2012, 05:08:30 PM
It was flying so stable, nice! Sorry about the damage - albeit minor...

--Ates


Title: Re: Bostonian Bede BD5
Post by: OZPAF on October 30, 2012, 07:53:19 PM
You had that fellow to the right of the fire doors worried ;D It does fly nicely Jon. now we know why you wanted to use a front hook - I mean tricycle undercarriage ;D
have fun
John


Title: Re: Bostonian Bede BD5
Post by: biggles0106 on October 30, 2012, 08:12:11 PM
She is absolutely beautiful. Are there any plans available, or is it totally designed and built by you Jon?


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on October 30, 2012, 08:16:58 PM
now we know why you wanted to use a front hook - I mean tricycle undercarriage ;D

:D ;D

Biggles, thank you. Yes it's my design but I have drawn a plan which I intend to upload here at some point: if I can get the thing flying that is!


Title: Re: Bostonian Bede BD5
Post by: biggles0106 on October 30, 2012, 08:23:33 PM
You are almost there! Plans would be wonderful.
Thank you,
- Mike


Title: Re: Bostonian Bede BD5
Post by: Pete Fardell on October 30, 2012, 09:07:49 PM
Well honestly, what a silly place to put a fire door. Great to see her flying though! Look forward to more.


Title: Re: Bostonian Bede BD5
Post by: Dave Andreski on November 03, 2012, 12:26:07 PM
Jon,
I think your BD5 is flying at a nice speed.
After a few 'nervous' trimming sessions, you'll will have it doing what you want.
Dave


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on November 27, 2012, 07:35:31 PM
I managed to get the BD5 all fixed up and took it outside to give it some space on friday. I had a couple of promising flights but there was a lot of windshear and she spiralled in busting the wing properly this time. The wing will need a total rebuild now :-\ :sigh:


Title: Re: Bostonian Bede BD5
Post by: biggles0106 on November 27, 2012, 07:45:30 PM
It will be worth it in the end!


Title: Re: Bostonian Bede BD5
Post by: OZPAF on November 27, 2012, 07:46:10 PM
Bad luck Jon. It sounds like it may have been a case of just more turbulence than it could handle. Spiral stability on this model would be an interestin exercise though. With a pusher prop adding more effective fin area perhaps more dihedral is required compared to a normal tractor layout. I'm sure you took all this into considration though.
John


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on November 27, 2012, 08:11:22 PM
Tell me about it - the saga continues...

John, I actually wasn't too worried about spiral stability - before friday! It has quite a chunk of dihedral but it did seem twitchy in the gusts. It seemed ok on the (few) indoor flights, in fact at one point indoors I though it may have been 'under finned' ie lacking yaw stability  :-\ As I suggested I've mostly forgotten whatever aerodynamic reasoning that was behind the original design (should build quicker :)) but I'm not so sure if I had thought of that. I was thinking that the pusher prop was stabilizing in yaw, but maybe forgetting the effect on the spiral mode... I remember that Tobgun's peanut was "surprising stable" for it's dihedral but of course it had less of a chunky fuselage.

I think the wing was just too light anyway so I haven't had chance to get any consistency yet. Next one will be quite a bit tougher.

I'm shelving it for the moment: I've drawn and started building a new Bostonian design with a proper airfoil (BE50). It's going to be called a Boston Beagle ('cause it has a long but square nose) and a less indecent tail moment arm (!).


Title: Re: Bostonian Bede BD5
Post by: rgroener on November 28, 2012, 02:24:00 AM
Jon, sad to hear that your Bostonian BD5 isn't anymore... Looking forward to #2 :)
You are building a new Bostonian?! Popcorn is ready, you can just start to post the progress ;D

Best regards Roman


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on November 28, 2012, 06:03:58 AM
Hi Roman, just the wing that needs a rebuild fortunately - the fuselage is fine.

I'll do a thread on the new one soon - it's a 'characterless' bostonian though!  Designed to win (hopefully) ;D


Title: Re: Bostonian Bede BD5
Post by: rgroener on November 28, 2012, 06:42:53 AM
Jon, good to hear that the fuse is fine. Looking forward to the thread.

Bostonians are never characterless :D

Roman


Title: Re: Bostonian Bede BD5
Post by: biggles0106 on December 19, 2012, 01:44:42 PM
Any further flights?


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on December 19, 2012, 04:57:59 PM
Hi Biggles, fraid not... repairs are on the to do list but don't hold your breath  :-\


Title: Re: Bostonian Bede BD5
Post by: fred on February 18, 2013, 11:09:55 PM
IF you want a BD5 Look Here: (looong thread with masses of info and photos tho)
 http://www.rcgroups.com/forums/showthread.php?t=20785&highlight=bd5
 I have built one and 'exquisite' is an understatement. the plans are 100% accurate and legible to even a bumbler like myself.
http://www.rcgroups.com/forums/showthread.php?t=293026


Title: Re: Bostonian Bede BD5
Post by: Dave Andreski on February 19, 2013, 12:53:22 PM
IF you want a BD5 Look Here: (looong thread with masses of info and photos tho)
 http://www.rcgroups.com/forums/showthread.php?t=20785&highlight=bd5
 I have built one and 'exquisite' is an understatement. the plans are 100% accurate and legible to even a bumbler like myself.
http://www.rcgroups.com/forums/showthread.php?t=293026
Or you could stay closer to the current topic/thread and build from the P-Nut plan I uploaded to the Plans Gallery today. ???
Dave


Title: Re: Bostonian Bede BD5
Post by: biggles0106 on February 19, 2013, 01:43:31 PM
Has anyone built the Nick DeCarlis  5 for RC?


Title: Re: Bostonian Bede BD5
Post by: Dave Andreski on February 19, 2013, 01:44:58 PM
Has anyone built the Nick DeCarlis  5 for RC?
Who can say?
Will you be the first?
Remember... this is an INDOOR Freeflight subject.
Dave


Title: Re: Bostonian Bede BD5
Post by: biggles0106 on February 19, 2013, 02:12:00 PM
I am sure there are indoor RC planes (at least I am told there is such a thing)....but a BD5...who knows - maybe I will be the first!!  ;D

Mike


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on February 19, 2013, 02:18:37 PM
Thanks for the link Fred. Of course this one is only 75% BD5, but 100% Bostonian :D

The BD5 repairs are working there way to the top of my to do list. I do intend to produce a finished plan but I would like to get it flying reasonably first...

The peanut version looks good. Thanks Dave.


Jon


Title: Re: Bostonian Bede BD5
Post by: fred on March 02, 2013, 01:59:06 PM
Clever use of the Lego as Build jig.
 My kids had Lego Mats as well... quite large sheets actually,
 It just occurred to me that A Lego Mat could be good to place/lock the Lego onto for accurate/semi permanent Jig fits.
 
OK.. Just added the links as reference. I thought it was on topic ??
Note that one can print those plans at.. Any.. scale one chooses to, even tiled.. as the freebie Acrobat X+ reader now allows it.
 It builds into a ~40 gram model.. as is... sans avionics of course.
 


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on October 31, 2013, 01:09:02 PM
.... Finally got around to repairing the little rocket ship. I had to build a new port wing from scratch, but it's hard to tell other than the old one looks scruffier.

Hopefully I'll get this flying soon.


Title: Re: Bostonian Bede BD5
Post by: danmellor on October 31, 2013, 03:02:03 PM
Yeah!!

Dan.


Title: Re: Bostonian Bede BD5
Post by: HGF on December 14, 2013, 01:44:42 PM
That is just wonderful. I did build the DeCarlis peanut back when the plan came out, and did find it flew pretty well. I simply made it too heavy. I still have the two piece canopy mold I made for it.
Any chance the plans are available for this delightful Bostonian version yet?

H.G.


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on December 14, 2013, 02:30:32 PM
Hi, I'm just waiting until I can get some proper flights in but that should be in a few weeks time.

Thanks for the interest,

Jon


Title: Re: Bostonian Bede BD5
Post by: FreeFlightModeller on December 14, 2013, 02:52:38 PM
The next Bushfield Jon? Hope to get there again myself, so I hope the weather doesn't turn to proper winter (we've been lucky so far I think)
I've not been able to get to any of the meetings lately ..... was hoping to get there next Friday but I'm double booked with another do  :(


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on December 14, 2013, 03:32:33 PM
Hope so Russ, I couldn't get to the last one because I was away for the weekend.


Title: Re: Bostonian Bede BD5
Post by: FreeFlightModeller on January 07, 2014, 03:48:35 PM
Another video from the weekend ... Jon trimming his newly repaired Bede.

http://www.youtube.com/watch?v=oAvJi7P7r_k (http://www.youtube.com/watch?v=oAvJi7P7r_k)


Title: Re: Bostonian Bede BD5
Post by: HGF on November 22, 2018, 07:36:45 PM
Any further news on your delightful BD-5 Bostonian? I'd love to give one a try!
Henry F.


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on November 23, 2018, 05:08:04 AM
Hi Henry,

I haven't touched it since the session shown in that clip I'm afraid! It was a bit of a beast to trim with the short tail moment arm. I think I have the plan somewhere though.

Jon


Title: Re: Bostonian Bede BD5
Post by: vtdiy on December 19, 2018, 09:38:10 PM
Really Loved this thread and your model Jon! It's beautiful and different.
Watching the video, I couldn't help wondering if a little reflex in the TE could tame it. Don't know of any easy way to do that, so it's Just idle curiosity.


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on December 22, 2018, 08:06:55 AM
VT - sorry I missed this. Thanks for the kind words.

I think the phugoid problem is a result of poor inertia qualities from the long nose combined with weak dynamic longitudinal stability from the short tail moment. However the static stability is large (tail volume is around 0.8 ) which probably exacerbates the phugoid problem. The strong static stability is good while in trim but once disturbed it tends to fight the weak dynamic damping. It might be better to reduce the tail volume and tail area.

Adding some reflex might reduce the pitching moment a bit and so permit a smaller tail but to be honest the airfoil is pretty low camber already and so I'm not sure it would make much difference.

I haven't really tried to get the best out of the model though so it may well respond if I gave it some time. I still have it - but it's been in a box for about five years!

Thanks for the input,

Jon


Title: Re: Bostonian Bede BD5
Post by: lincoln on December 22, 2018, 06:11:40 PM
My guess, from watching the video, is that either it had too much up elevator, or it needed to be trimmed with the c.g. further back. (Obviously you'd need less up elevator then, too.) Moving the c.g. back reduces the static stability without changing the dynamic stability all that much. Shrinking the tail, OTOH, does both.


Title: Re: Bostonian Bede BD5
Post by: Yak 52 on December 22, 2018, 07:09:03 PM
Thanks Lincoln, yes this is probably the case too :) I can't honestly remember what I did now but it did end up with a fair bit of noseweight.


Title: Re: Bostonian Bede BD5
Post by: vtdiy on December 22, 2018, 10:51:03 PM
Jon, do you think you might be taking it back out of the box any time soon? Just seems a shame not to get such a nice plane flying the way you want it to.


Title: Re: Bostonian Bede BD5
Post by: FLYACE1946 on March 02, 2019, 06:38:37 PM
I just located the DeCarlis peanut plan and was wondering if any body knew if it ever had
an article  published on it's construction, maybe Model Builder?

I used to visit the hanger where the dealer sold the full scale Bede's up near Arlington or maybe Grand Prairie, Texas. He had two under construction.


Title: Re: Bostonian Bede BD5
Post by: Indoorflyer on March 03, 2019, 11:04:53 AM
Pretty sure it was published in Model Airplane News.  I don't have a digital copy of the article, maybe MAN can help.