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Frank Day08/08/2020 17:35:14
7 forum posts

Hi,

Hope this is posted correctly?

It has been many years (40 plus) since I last ingested clouds of balsa dust and it was all balsa cement and 35mhz. Like others who have posted recently growing up and becoming "responsible" put paid to my RC flying days.

A while ago I acquired a few old IC trainer type models from someone I was working for. Bit of tinkering and they all run and the electrics work. One I converted to electric and works well. The others not so much, mouse damage etc. One has a fberglass fuse, I think its an Avondelli? Cessna high wing style, will fly with a little TLC but not really interested.

Having caught the bug again I bought a foam 4ch trainer and apart from one nose off "heavy landing" its going ok. I blame that on sudden strong wind that sent it soaring like a rocket and disappearing into the distance,I managed to recovered it but battery was gone and couldnt pull it back up enough, though it has now been passed as airworthy again!

Im now also using the converted trad build model I converted to electric, wing is huge, flies slow and glides nicely so not to scary, dont want to crash it. I also added my new favourite item a 3 axis gyro.

The reason for the post is I bought a part built Tony Nijhuis 62" Typhoon, nicely built to the point of sheeting. Built by an older guy, sadly now passed who was a prolific builder from plans, no cnc kits right up to the point of sheeting when he would stop and build something else.

I know the plans were from 2007 so ancient news but looking for some advice on the model if someone still has one. I have read that a lead mine may be needed to acheive the correct CG,(1-2lb) with that in mind my plan is a 1kg RCV 120SP 4 stroke, will need a 15mm extension to the fuse but im ok with that. Also advice on RDS control surfaces.

Post is probably a little long but adice welcome.

Denis Watkins08/08/2020 19:42:46
4633 forum posts
129 photos

On this plan the motor is 10cc for a 7lb model Frank, do you really need a 20 cc motor

**LINK**

Frank Day08/08/2020 21:29:02
7 forum posts

Hi Denis,

Thanks for the reply.I've been on the Nijhuis site

Having read a few posts about the model needing 1-2lb of lead in the cowl, I thought to replace dead weight with more engine and a 3 blade prop. The RCV SP range has a 2 -1 reduction in prop speed so allowing for a better scale appearance. I also have a RCV91CD @800g. that would fit inverted but is slightly longer. The .60 size engine seems undersized compared directly to the recommended engines in other models of similar weight fromTony. A few members seem to believe the quoted 7lb is not realistic with experienced builders ending up at 8lb plus so not quite sure where mine will end up. I have to confess I do like to oversize engines/motors.

Its been a long time since I built anything and a lot has changed. I really dont like exposed servos and rods/horns so im also looking at RDS or IDS as ive seem them described system whilst the model is un-sheeted

Dale Bradly09/08/2020 02:34:38
39 forum posts
12 photos

Firstly, check what size the Typhoon was actually built. The free plan as printed in RCME way back then was the wrong size, (too small) and plenty of people commenced building it at this size before realising. (hence a 20cc motor will be ludicrously big). (The plan as supplied on the TN website is provided at the correct size).

Yours will end up heavy. The only one in the entire world that was the correct was TN's original, and no mere mortal has come close to equalling that by following the plan. A big engine will not make it lighter. I think you're waaayyy too big with the 1.20, it will fly fine on a 90 4st or thereabouts

Rereading my thread, i had the equivalent of about a 90 4st in electric power and about 685g of steel ballast, and 60g of lead. I recall its about 5kg total weight. If i did it again, i certainly would not want any more power in it, rather i would make more effort to make the whole aircraft lighter. I would sacrifice RDS and other nice to haves, the plane is too small to justify as this is just more weight.

Mine

Frank Day09/08/2020 10:23:00
7 forum posts

Hi Dale,

Thanks for the reply. I looked at your photographs and a picture really does save a thousand words.and I will be refering to them during the build.

I did take a tape measure to it and it is 62inch rather than the 40 size I believe. the original article produced.

I got lucky with this ebay purchase, the original builder produced copies of the plan as well as a full set of cutting templates and laminated paper copies of every piece should spares be needed, (3 A4 size box files) hopefully not!

Looking at the weight of the electric set up and reading a number of posts, re using the second battery as ballast it seems that Tony is the only person who didnt need a whole bunch of additional weight up front. The electric motor and batteries I looked at seem to come in at around 500g excluding ESC. I think you also added 745g of steel and lead. 1345g in total-ish

Did you build the engine mount with the built in thrust angle or is this something builders dont bother with?

It was always my intention to go with a ic engine, The 120 with muffler is 1005g and the 90 is 800g excluding fuel and tank. May be the 90 is the way to go.

I'll also have to do some research into coverings and paint to keep the weight down, it seems to make a surprising difference. Tissue paper and dope last time I did this and i'll save the RDS for a later date.

Gear doors seem likely to be an issue, getting the wheel into the well and the door flush is going to take some tinkering, gear down I can visualize the doors would need to be mounted "toe in" on the struts? and the wheels when housed will be angled within the well so width of the wheel may also be an issue. Advice welcome.

Dale Bradly09/08/2020 21:50:20
39 forum posts
12 photos

Hey Frank, more than happy to dredge up other photos etc if you require. I enjoyed building it, and it is a great flyer. Sing out if you need anything else.

I don't recall any down/side thrust, i'll pull it out and check someday soon. I did build it "as per plan" so would have done whatever that said.

The wheels on mine sit well and good both retracted and extended, (90° retracts, Eflites i think), following the plan.

The doors do have some level of "toe in" on the struts when extended, probably why the gear is so draggy. I'll photograph this too.

I would take pains to build up all the tail surfaces as light as possible, (I recall there is something like 12mm solid for the rudder?), and build everything as light as possible. I'd also give serious consideration to iron-on or tissue/dope for covering, i glassed mine which i prefer on my models but wouldn't next time. Again, lightest tailwheel you can find. Mine is castoring (not steerable at all) and it's ground handling is surprisingly good. Aileron servos as far forward in the wing as possible. elevator/rudder servos right up front. Consider pull-pull.

The morals of the story: 1. Put every effort into getting weight down. 2. Put every every effort into getting what weight you must have forward. 3. In that order, because there just isn't anywhere forward to put balancing weight!

Don't let this put you off, it is a great flyer and a great design. I just built mine heavier than TN did, and paid the consequences.

Dale Bradly09/08/2020 22:31:00
39 forum posts
12 photos

This photo was missing from the other forum. 2x solid steel cannon barrels in black!

img_20140824_105642 (2).jpg

Dale Bradly10/08/2020 07:35:32
39 forum posts
12 photos

20200810_181208.jpg

This pic is approx "front on" to the gear leg, and shows a couple degrees or so of toe on the gear door. (i.e. you can see the grey outer paint, not the green inside).

A couple of other pics that might be handy. (Note i didn't put on the triangle inner doors), and i think my doors might be shorter than scale. No anoraks have ever pointed out the difference, but i also don't compete in scale competitions). Note also i built a three piece wing, so my inner spar will be different to yours.

20200810_181300.jpg

dsc08960.jpg

img_1949.jpg

Frank Day10/08/2020 07:41:08
7 forum posts

Hi,

Once again thanks for taking time to reply.

You're right 12mm slab rudder, fin is a 3 layer balsa laminated affair, unfortunately the fin I have is warped, grain all laid in the same direction though it may be a template the guy made.. Im guessing the rudder will go the same way. I'm considering rebuilding these with a thin skin over a simple frame. I'll cut it all and throw everything on the scales first just in case I manage to build it heavier than the slab.I dont mind a little trial and error/waste and will be useful practice

Iron on coverings, nightmare! too many differing opinions. Have never had a go at this but have read a few bits.Will cover some random shapes and surfaces first. I will def need some advice on this:

Paintable covering: confused by all the forum discussions on right product

Sand and seal before covering or just sand. TN used Solartex and prymol I think but that may be old news by now.

Thanks

Bob Cotsford10/08/2020 13:07:02
avatar
8746 forum posts
489 photos

In the Warbirds Replica La7 thread Ron Gray used document laminating film to good effect, that looks like quite a light approach that avoids cellulose dope fumes. I used brown paper and PVA but as didn't weigh it before and after I don't know how much the paper finish added but it was quick and easy. If I could stand the fumes I'd go with tissue and dope with Tamaya acrylics airbrushed on for the colour. I don't think you could get anything lighter and easier to apply.

The late and great BigglesElderBrother (David Burton) did a TN Typhoon build in which he discussed U/C mounting geometry in some detail if anyone can locate it again.

Frank Day10/08/2020 15:18:03
7 forum posts

Hi, Bob & Dale,

I'll try and find the David Burton article and do a little more reading on the covering materials, light and paintable needed.

Should I seal the balsa before covering (iron on)?

I have been looking at your wings and the cogs have been turning but I think i'll stick to a standard-ish build, as the wish list may surpass the current skill level

Looking at the pintle angle and doors I thought tthat may be the case. My wing has had one half of the underside sheeted, I guess the builder either had no intention of adding doors or they would be minimal as the hole cut only allows for the 90mm wheel and strut to pass through and isnt cut anywhere near the area on the plan. Will probably open that out a little but not full size. No shows for me either.

I have thought about the inner door and could hinge it and close it with a lever at 90deg or thereabouts pushed up by the retracting wheel but how to stop it flapping about when down, may be something springy attached to the hinge. Will leave that till much later.

Steel cannons look like a good way to aid the balance.

Thanks again for the info and pictures.

Simon Chaddock10/08/2020 17:12:22
avatar
5776 forum posts
3055 photos

Would steel cannon barrels attract the attention of a club safety officer at any sort of "meet"?

Frank Day10/08/2020 17:15:51
7 forum posts

May be if they work. different rules/regs in NZ possibly

Dale Bradly10/08/2020 17:19:39
39 forum posts
12 photos

Re steel, never been, nor do I forsee a problem. YMMV.

Dont seal before iron on covering, nothing to be gained there.

Bob Cotsford10/08/2020 17:30:02
avatar
8746 forum posts
489 photos

Yes, iron on coverings only need a dab of Balsarite Balsaloc or similar on areas that iron on coverings don't stick well to, ply or plastics generally.

Denis Watkins10/08/2020 17:49:03
4633 forum posts
129 photos
Posted by Simon Chaddock on 10/08/2020 17:12:22:

Would steel cannon barrels attract the attention of a club safety officer at any sort of "meet"?

Although the BMFA recommends

" c) It is recommended that rounded spinners or safety propeller nuts of the domed type are fitted to internal combustion and electric powered models and that gliders and pusher powered aircraft noses should also be rounded (no needle noses) "

and have had conversations at shows about pointed metal shapes on models, e.g. Pitot tubes

If informed at the field of steel barrels, then the model would not be allowed to fly until changes were made.

trevor wood 211/08/2020 09:22:15
avatar
59 forum posts
56 photos

image.jpegI was lucky to win the online auction for BEB's part built Typhoon last year and have been working on it (albeit very slowly!) over the last few months. As received, the landing gear installation was as per the TN original without the inner gear doors. Apologies for the top photo being out of sequence.image.jpeg

I've managed to retro fit inner gear doors made from ply laminations and small nylon hinges. A short length of piano wire (about 28swg) is attached to an operating arm on the door and its other end is anchored to the wing structure at the base of the wheel well. As the gear approaches the fully retracted position it hits the wire and pulls the inner door closed. The length of the wire is critical in ensuring the door travels from fully open to fully closed, and (in my case) was achieved by trial an error. Hope this helps.

You may notice that I've also managed to make provisions for flaps. TN said that these weren't necessary as the model flew like a pussy cat, but I fly from a short with obstructions on the approach so I felt it was a wise precaution to take while I had the opportunity.

image.jpeg

Dale Bradly11/08/2020 11:15:29
39 forum posts
12 photos

Nice!

Bob Cotsford11/08/2020 11:44:12
avatar
8746 forum posts
489 photos

I like the wire activator idea. On my Macchi I used a micro servo mounted on top of the centre section sequenced to open and close the doors at appropriate times via pushrods to lugs on the two doors. If the oleo pins are straight and the mounts positioned as per the plan then BEB most likely decided that an accurate u/c motion was too problematic and not worth the effort needed on a sport scale model.

In all honesty I don't put leg covers on many models as they are just too much trouble when flying from grass.

Edited By Bob Cotsford on 11/08/2020 11:45:14

Frank Day12/08/2020 15:01:30
7 forum posts

100% I will be ripping off the wire actuators idea, any measurements and close up pics welcome.

Pics of blended piece by wing bolts and flat area on LE very useful. was thinking of putting two dowels in as drilling the centre would be on W1 and may allow some movement

As my model is still skeletal I've an opportunity to add some bits, though i'm mindful of the weight.

Query on the tail fitting TN's plan say make in two halves, cut through sheeting and butt join inside. (not sure about that) thought to make in one piece poke it through and secure then sheet, a little more time consuming may be.Trevor's model seems to have the top of the fuse opened up for fitting, any thoughts.

I would like some basic flaps and now would be the time to do it, subject to finishing my kitchen otherwise i'll be in trouble, would these need a full size servo or would something like a pair 9g do the job, have some plus weight consideration.

As my 1st post, im trying to avoid external control horns etc so i've mocked up a elevator torque rod with a 90deg spur that will connect internally so will leave some sort of access panel.

Sorry so many questions been 40 years or so since I built anything like this.

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