Spencer Original Design

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Rockiedog2

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Here's a few pics of the original design I've been working on for not quite 2 years.
Builtup spars mostly copied from the Double Eagle but shortened from 12' to 9'. RV3 tail. Wing area, airfoil(23012), aspect ratio, tail arm, aileron area and control throws are all RV3. Drag wire setup is Pitts. Torque tube aileron control and fully balanced ailerons. O-200 Continental and 70" Warp Drive 3 blade. 27 gal fuel in 2 wing tanks and a header tank. The wing tanks are the exact airfoil shape and won't be covered. That was a mistake...ran into all kinda stuff on that...I didn't foresee how much time and head scratching would go into the tank mounts cause of course they have to bear the airloads of the tank area. And they got heavy as my welder guy had to go to 050 to weld it. 9# each. To do over I would put the tanks in the wing and do 032 and Prosealed riveted seams. Probably save maybe 6# total. The uncovered wing panels weigh 40# each with the tanks installed so that would have been a significant % savings. The strut braced gear has a unique shock strut setup...very light, simple and a bit crude and elegant at the same time. I'll try to post a drawing.
I had the spars, lift struts and gear leg professionally analyzed. The rest of the airframe is pure eyeball engineering and TLAR. This is my 6th build so I do have a fair feel for what will probably work for me altho I would stop short of recommending my stuff to anybody. I have no idea what the redline is....will have to sneak up on that. The formula says the stall speed is 51 mph at 950 GW so that's LSA legal. With flat tip plates and VGs the stall should decrease to about mid 40s. The cruise speed can be kept LSA legal with the GA prop. If you don't care about LSA the thing should easily run up near small Continental powered Tailwind speeds. And oh yeah it's a single seat.
The original design goal was to build it to 500# EW. Last preliminary weighin showed projected 525 so not too far off. Go to light weight accesories and some detail weight reduction and we got near 500. Not too bad for a cabin monoplane that can be considered a fairly serious xcountry and utility plane. But it's bare bones and raw. That's the way I like em. It's really blind on the ground due the steep stance. That due an attempt at the Aviat 110 Special(Monocoupe descendant) look...very studly IMO. And it's narrow geared and tall...I've always liked flying little airplanes that challenge you just a little bit.
The mutt in the pics is my roomie Rockie. He considers himself the inspector. In the first pic he's laughing his a** off that his roomie thinks he can maybe design an airplane. Smart dog...

Any comments, suggestions, observations welcome....I'm a pure shadetree

Joe Spencer in Mississippi



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TFF

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I have seen it on the Legal Eagle site. Looks good.
With the short span are you going for good roll rate. How does the RV tail feathers compare weight wise to tube steel?
 

Autodidact

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The back view makes me think of a clip wing T-craft, are you going to loop and roll it a little? It's a good looking aircraft.
 

Autodidact

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Usually, a lot of us - including myself - say things like: "You shouldn't mix and match parts from different planes...", "You need to do an analysis...", or "You really ought to at least do a sandbag test to verify that fuselage truss...", but it almost always makes people mad, I don't know why :ermm:... But, I will stand by my first statement, it's a nice looking airplane.
 

Rockiedog2

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I have seen it on the Legal Eagle site. Looks good.
With the short span are you going for good roll rate. How does the RV tail feathers compare weight wise to tube steel?
best I could figure the tail weighs 7# more than the Baby Ace tail(i used the Baby Ace plans for estimating weights and arms to try to get the wt and balance in the ballpark. last weighin looks like gonna end up about 25% loaded CG. that's fine...)
 

Rockiedog2

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The back view makes me think of a clip wing T-craft, are you going to loop and roll it a little? It's a good looking aircraft.
aileron and barrel rolls ok. i'm not keen to start doing over the top stuff cause i got no idea what Vne is. maybe later
 

Rockiedog2

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Usually, a lot of us - including myself - say things like: "You shouldn't mix and match parts from different planes...", "You need to do an analysis...", or "You really ought to at least do a sandbag test to verify that fuselage truss...", but it almost always makes people mad, I don't know why :ermm:... But, I will stand by my first statement, it's a nice looking airplane.
Naw man you won't make me mad. Yeah you're right it oughta be analyzed and all that but it'll "probably" be all right...if it's not i'm old enough it won't be tragic if I auger in.
Being so intimately familiar with the Pitts, Acrosport and Tailwind I'm confident the structure is sound up to some speed. I do wish i knew what that speed is. I'm not worrying about flutter due the RV3 tail has such a sound history and the ailerons will be 100% balanced...i just don't know what all is considered when figuring Vne and the process.
I can fly by the numbers...but this is the first plane i've flown that nobody knows what the numbers are. LOL
Thx for the replies and compliments guys. Any info on figuring(estimating is ok) the Vne appreciated
 

Autodidact

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Being so intimately familiar with the Pitts, Acrosport and Tailwind I'm confident the structure is sound up to some speed.
That's sort of what I figured.

I'm not worrying about flutter due the RV3 tail has such a sound history and the ailerons will be 100% balanced...i just don't know what all is considered when figuring Vne and the process.
I think it could be due to gust loading or flutter speeds, either one, depending on where a failure will happen first. Other people can say better than I can. If it's gust loading, then if the RV tail is stronger than the rear fuselage, or the tails attachment points, then it's the weakest link that is important.

It looks to me like the upper longerons extend all the way back to the forward stabilizer attach points?
 
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Autodidact

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Rockiedog, here is a good thread from VAF about the subject of Vne. It appears that the FAA requires that the cruise speed be 33*sqrt(W/S), Vd to be 1.4*Vc, and Vne to be 0.9*Vd. If you know that your structure is stronger than various examples of certified aircraft, then maybe those are the speeds to creep up on? If your wing loading is 9,74 lb/sqft, then 33*(9,74^.5)=103mph, 103*1.4=144mph, and 0.9*144=129.6; that's supposedly what the FAA requires for certified aircraft, and it might be knots instead of mph, but mph is a more conservative number. VAF:How is Vne calculated? - VAF Forums
 

Rockiedog2

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Rockiedog, here is a good thread from VAF about the subject of Vne. It appears that the FAA requires that the cruise speed be 33*sqrt(W/S), Vd to be 1.4*Vc, and Vne to be 0.9*Vd. If you know that your structure is stronger than various examples of certified aircraft, then maybe those are the speeds to creep up on? If your wing loading is 9,74 lb/sqft, then 33*(9,74^.5)=103mph, 103*1.4=144mph, and 0.9*144=129.6; that's supposedly what the FAA requires for certified aircraft, and it might be knots instead of mph, but mph is a more conservative number. VAF:How is Vne calculated? - VAF Forums
hey thanks for that. i'll try to work thru that. very good!
 

Rockiedog2

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Thought I'd post an update on the new plane. Got it signed off last weekend so the hard part(the p/w) is done. Still working on essential details before first flight such as the Black Max 1000 brakes don't have much stopping power. Increasing the pedal leverage on those but not optimistic. The diameter of the disc is only about 4" so no leverage there. Had a mag die so waiting on a new pair...stuff like that. Still have to make a lotta fairings etc. So it'll be a while yet. Wondering about the ailerons as they are a total guess. Dunno what kinda roll rate/control effort is gonna be required. Mostly Tailwind control leverages but with some differences. We'll see. Came out 569# with an ancient homemade small Continental of unknown power. My dad built it up outa parts on hand about 40 years ago. Runs strong and good compression/oil pressure. May blow up at any time who knows. Put all new lightweight accessories on it...mega bucks. 27 Gal fuel so maybe about 5-5.5 hours range at probably about max LSA speed. I was ok with the weight even tho over early wish but the mission changed to full blown x/c machine so the weight went up with that. Shoot, I even got cabin heat. It accels like a bat outa hell...bout like a 180 horse RV8. On full power taxi tests at about 300' of roll had to come outa the power as it was ready to go. Calculated Vso is 50 mph, one under the magic 51 for LSA limit. Put a glass panel in it cause weight/simplicity even tho I dont like glass...total outa character for this thing. Well, it was the weight advantage but it was an agonizing decision. I flew the stuff when I was working and didn't like it then. Some of us are still stoneage. Tail, tailarm, span, aspect ratio, and control throws for tail are all RV3 but it weighs about 150-200# less than an RV3 so yeah the tail works really good...nearly stood it on the nose first time. If it turns out to be a pretty good plane already have major surgery planned to get some weight off of it.
It's tall, short, narrow, top heavy, and blind as a bat. Oughta be fun...

https://www.youtube.com/watch?v=0Ce5AuFvt0M

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Autodidact

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That's awesome Rockiedog!

By the way, I think one of the Aussie members mentioned your accent. I don't think he meant redneck; he did say "southern" accent, and a southern accent is a musical thing, actually rather pleasant to the ear.

Nice looking airplane.
 

Pops

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Naw man you won't make me mad. Yeah you're right it oughta be analyzed and all that but it'll "probably" be all right...if it's not i'm old enough it won't be tragic if I auger in.
Being so intimately familiar with the Pitts, Acrosport and Tailwind I'm confident the structure is sound up to some speed. I do wish i knew what that speed is. I'm not worrying about flutter due the RV3 tail has such a sound history and the ailerons will be 100% balanced...i just don't know what all is considered when figuring Vne and the process.
I can fly by the numbers...but this is the first plane i've flown that nobody knows what the numbers are. LOL
Thx for the replies and compliments guys. Any info on figuring(estimating is ok) the Vne appreciated
Yep, you won't forget the first flight when you have no idea of any numbers. Been there and do that. Rotated when it felt like it wanted to fly, climbed at what felt good, ( after all the testing, that speed gave me the best ROC) , so I lucked out. Stayed over my airport and after I got more of the feel of it, I slowed it down to where I had somewhat of an idea of the stall speed without stalling it and then used the good old reference of 1.3 times that speed for my approach speed. Probably the best landing I ever made it the darn thing. That was 7 1/2 years ago and I love the little airplane.
BTW, I really like the looks of your airplane . It will be somewhat hotter than my JMR Special that I am working on. Look it up on this site.

Dan

Added -- I can see a round cowl on it.
 

Rockiedog2

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>>>Added -- I can see a round cowl on it.

hey Pops. i originally had a NIB Rotec radial for it. bt it off ebay for think it was 14K. went up to KC and talked to that dude up there that builds all the replica biplanes with rotecs. looked one of his motor over pretty good. didn't like it. too complicated/heavy and was gonna change the whole design philosophy of see how light/simple we can make it. called the seller and told him it wasn't gonna work for what I was doing. told him a new one was 20K+ or something and did he want it back? he sent my check back, he hadn't shipped it yet. i didn't wanta fool with the thing, didn't even wanta get it in here and resell it too much trouble. us older guys have to prioritize our time. no regrets but that would have been an interesting plane. real interesting. i looked at your JMR Special a while back. Nice, yessir. you've built a lotta planes.
this one handles nice on the runway so far. surprisingly, but the strip is soft right now that helps. it's a little quick but solid and predictable and doesn't like over controlling. course you can't see a thing for about a 45 degree arc in front of the pilot. bout like a Pitts. Not a problem when you get used to it and figure out to just look straight ahead and let your peripheral tell you what to do. first time in a small biplane i tried to look over the side and around the nose. that doesn't work, all over the runway. any old Pitts drivers here know all about that.

can you imagine an *Aussie* saying anything to anybody about their accent?
actually, i thought everybody but us had the accent Pops.
 

Rockiedog2

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Like a little Howard DGA.[/QUOTE]

yeah and if skinny the aft fuse down it wud look like a Monocoupe. especially if built a Pitts tail which weighs near nothing and shape to match. i wanta do that regardless after fly it a while and see if its worth all the trouble. the deck angle(a little steep) came from the Aviat 110 Special which was a takeoff on the Monocoupe. semi went for that look. the cg came out a little aft so those 2 mods would probably fix that. maybe overkill.

https://www.google.com/search?q=aviat+110+special&tbm=isch&tbo=u&source=univ&sa=X&ei=ymUoVaK4IYqCsAXjiICgDw&ved=0CCUQsAQ&biw=1920&bih=943

deck angle is 16 degrees on SS-1 and 110 Special. looks kinda aggressive to me. the little short squat ones always looked a little funky to me.

thx for all the interest folks.

RD
 
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