By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by CML

Precedent Stampe 1/4 Scale

build blog

All Topics | Latest Posts

Search for:  in Thread Title in  
bert baker09/08/2019 13:58:11
avatar
1524 forum posts
317 photos

0eb103b0-aed8-400b-8d27-4cafd15afddc.jpeg

cymaz09/08/2019 14:02:10
avatar
9041 forum posts
1189 photos
Posted by Jon - Laser Engines on 09/08/2019 13:56:36:
Posted by cymaz on 09/08/2019 13:34:53:

And, finally, the CG is incorrect on the plansurprise

I balanced mine at the marks on the plans and its spot on :\

Bert, its the cabanes that are the issue as the top spar ends just outboard of them so the cabanes do not take any of the lifting loads. Its all transmitted to the lower wing through the interplane struts. I will probably extend the spar on the next one and use some sort of steel plate for strut attachment.

I balanced mine and it was wayyyy tail heavy. It’s in the blog somewhere.

bert baker09/08/2019 14:03:02
avatar
1524 forum posts
317 photos

Ah, ok, been long morning,,

will rigging sort it out

yes before the hounds desend the previous owner who part built the plane decided to cover the top of the top wing first ....

bert baker09/08/2019 14:05:22
avatar
1524 forum posts
317 photos

 

I really dont understand why there's no lift support, the cabaine is fastened to the fuz,the ply plate is bollted to the cabaines, the top and bottom spars arew glued to the ply plate, perhaps with a shear web inbetween

 

is it because the diheaderal has to be fitted at some point

 

Mine would balance better if I had a Laser 180 Petrol,,

just wiping the rain from the naughty step,,

but Jon has just rebuilt my glow 180 and it does run sweet

Edited By bert baker on 09/08/2019 14:14:39

Edited By bert baker on 09/08/2019 14:18:27

Martin McIntosh09/08/2019 15:08:47
avatar
3159 forum posts
1136 photos

The main reason that I should have thought more about the u/c and maybe cabane strut position before building is that with a fs motor there is nowhere for the original tank.

Whilst people are digging out their plans I would greatly appreciate it if someone would measure the incidence between, say, the tail and the top wing. I have heard that some versions of the plan show the wrong tail incidence, and guess which one I built. My elevator has to droop by some 20deg. but does not seem to affect the flying. Nothing I can do about it now but it would just be nice to know since with each side built from 1/4sq. spruce over the plan it would be difficult to get it wrong. Looked for my plan but it must have been chucked in the loft.

I expected a large cg shift with the heavier motor but it is only about 1 1/2" forward of the top wing centre TE and since the model still spins as before I shall leave it alone.

Jon - Laser Engines09/08/2019 15:48:54
5219 forum posts
254 photos
Posted by cymaz on 09/08/2019 14:02:10:
Posted by Jon - Laser Engines on 09/08/2019 13:56:36:
Posted by cymaz on 09/08/2019 13:34:53:

And, finally, the CG is incorrect on the plansurprise

I balanced mine at the marks on the plans and its spot on :\

Bert, its the cabanes that are the issue as the top spar ends just outboard of them so the cabanes do not take any of the lifting loads. Its all transmitted to the lower wing through the interplane struts. I will probably extend the spar on the next one and use some sort of steel plate for strut attachment.

I balanced mine and it was wayyyy tail heavy. It’s in the blog somewhere.

I have no doubt. Mine balances about on the rear bolts for the top wing i think. At this point it sits slightly nose down as i would expect a biplane to sit. The tail on mine has +ve incidence (down trim) and i fly it with further down trim on the elevator.

bert baker09/08/2019 15:52:00
avatar
1524 forum posts
317 photos

Can agree on cabaines being removable..

I have another Stampe that has suffered a crash and the cabaines are slightly twisted,And a small bent where it disappears into the fuz.

To awkward to straighten,

I plan to cut all the cabaine wires and slide brass tube over them and jig the wing into plane and silver solder the tubes to the wires

Jon - Laser Engines09/08/2019 15:59:06
5219 forum posts
254 photos

Bert the issue comes from the top spar ending outside of its support. As lift builds on the wing the lower spar is in tension but as its end is not connected to anything it is not restrained very well and the wing bends quite easily. The flat ply crutch thing in the middle of the centre section is supposed to take the load but i have found it pretty useless.

If its too late to mod the structure adding rigging will sort it. Sadly my rigging points are not strong enough for real rigging so i just have to fly gently.

Lets not forget that the model was designed around a merco 61 and was expected to be half the weight of most of ours so we are putting quite a bit more stress on it than it was probably designed for

John Bisset09/08/2019 16:17:47
208 forum posts

Looking at my plans for the Precedent Stampe, measuring the tailplane incidence (lower surface of tailplane) with reference to the upper fuselage longerons, which make a ~ good level reference, the tailplane measures at 4 degrees nose up.

(That sounds a lot. Mine is a kit from ~30 years ago, still not built. I will have to hunt around for an instrcution booklet; it's not in the box, so I must have taken it out to dream over.)

It's not so easy from the plans to determine wing incidence accurately. Looking at the plan and making my best guess of chord line, then transposing that up using (nautical !) parallel rules,the lower wing incidence appears to be around 5.5 degrees nose up. I'd suggest both my figures are +/- around 0.5 degree. Does that help?

I think both wings should have the same incidence at the root.

I have an aircraft engineer friend who is rebuilding a full size Stampe right now, and is close to re-assembling wings and tailplane. I could ask him what the values should be, though the model values may differ. I think his son has a Precedent Stampe part built.

John Bisset09/08/2019 16:19:52
208 forum posts

Jon, that sounds like the model needs the same tie rods for the lower wings as the real thing !

bert baker09/08/2019 16:24:57
avatar
1524 forum posts
317 photos

Hmm there’s many a Stampe out there with out rigging,and it was Not fitted as standard nor is the new kit.

I did ask as the display model at Slec stand Does have rigging, I was interested as at that point I hadn’t made the brackets,

these have all been made

my lad did a loop at full throttle with one that had no rigging and the wings snapped..

But this was on a very old beaten up one so no real supprize

I was fly with a chap who has a really nice example of a Stampe, up front is a SC four stroke Don’t know size, it to wasn’t fitted with rigging.

Edited By bert baker on 09/08/2019 16:29:02

Edited By bert baker on 09/08/2019 16:32:15

Edited By bert baker on 09/08/2019 16:32:56

Richard Acland09/08/2019 19:08:56
avatar
95 forum posts
31 photos

I found that although I built the correct amount of tail incidence on my Precedent Stampe I still need a massive amount of down elevator to achieve level flight. This model flies quite well using an SC 90 FS023.jpg

Edited By Richard Acland on 09/08/2019 19:14:42

Martin McIntosh09/08/2019 19:21:47
avatar
3159 forum posts
1136 photos

Thanks Richard, probably the same copy of the one which I used.

stampe 036.jpg

stampe 035.jpg

These pics show it I think.

Edited By Martin McIntosh on 09/08/2019 19:28:08

Edited By Martin McIntosh on 09/08/2019 19:29:11

Martin McIntosh09/08/2019 19:34:13
avatar
3159 forum posts
1136 photos

Thanks John B. Very helpful.

cymaz09/08/2019 20:32:43
avatar
9041 forum posts
1189 photos

Same here...huge down elevator needed

Nick Santovito10/08/2019 00:13:12
avatar
426 forum posts
63 photos
Posted by Martin McIntosh on 09/08/2019 15:08:47:

Whilst people are digging out their plans I would greatly appreciate it if someone would measure the incidence between, say, the tail and the top wing. I have heard that some versions of the plan show the wrong tail incidence, and guess which one I built. My elevator has to droop by some 20deg. but does not seem to affect the flying. Nothing I can do about it now but it would just be nice to know since with each side built from 1/4sq. spruce over the plan it would be difficult to get it wrong.

Hi Martin.

I measured my plans with a protractor during the build and came up with the following:


With the fuselage thrust line at 0....
Top wing 4 degrees positive.
Bottom wing 5 degrees positive.
Stab. 5 degrees positive.
CG: balances at the rear bolt of the top wing, I've flown as far back as the TE of the center section, but sometimes it takes 3 or 4 turns to come out of a spin.

Hope this helps.

Nick

Martin McIntosh10/08/2019 07:46:44
avatar
3159 forum posts
1136 photos

Yours sounds more like correct Nick.

It would seem that I am not alone with the massive amount of down. Was beginning to doubt my own building skills.

Nick Santovito10/08/2019 15:05:47
avatar
426 forum posts
63 photos

Was digging thru the old photos and found a couple that might be helpful for those who want to add rigging.

I used brass strips - about 1/64" - bent and drilled to accept Dubro clevises on one end as the plans show but with one extra hole for the wire clevis, and 1/2" servo screws on the other and just screwed them to the interplane strut mounts but sideways to the plans view , then soldered the uppers to the cabane struts. Finally recessed the lower wing saddle for the lower point and epoxied it in. I know I'm a hacker but I believe you could pretty this up a good bit.

Use 125lb clear nylon coated fishing leader for the wires.

It's held up for the last five years of rather bad flying. angry

img_1580.jpg

img_1581.jpg

I wish I had thought of mounting the gear on the bottom while building. I have my fuel tank exiting between the top of the forward struts and the bottom of the firewall extension. Could have mounted a bigger tank.

 

Edited By Nick Santovito on 10/08/2019 15:07:06

bert baker11/08/2019 09:37:02
avatar
1524 forum posts
317 photos

4a3bc823-0b74-4ad3-8bb0-e0b2e0db84e9.jpeg

bert baker11/08/2019 09:45:21
avatar
1524 forum posts
317 photos

Have been making some bits for the rigging wires.

the long piece screws to top of bottom wing, and will exit either side of the fuz.

two flying wires will go to the front top strut brackets.

I still have the rear top brackets to make,

I recall Cymaz using wings or parts of wings cut by Falcon Aviation.

i am intriguied as to what the difference is between the new kit and the Falcon parts,

I still have a origional die crushed kit that I have been keeping for prosperity,

I do fancy the look of the laser cut parts,

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of RCM&E? Use our magazine locator link to find your nearest stockist!

Find RCM&E! 

Latest Forum Posts
Support Our Partners
electricwingman 2017
CADMA
CML
Cambridge Gliding Club
Wings & Wheels 2019
Slec
Sussex Model Centre
Sarik
Advertise With Us
Latest "For Sale" Ads
Has home isolation prompted you to start trad' building?
Q: The effects of Coronavirus

 Yes - for the first time
 Yes - but Ive bashed balsa before
 No - Ive existing projects on the bench
 No - Im strictly an ARTF person

Latest Reviews
Digital Back Issues

RCM&E Digital Back Issues

Contact us

Contact us