Seagull PT19

[Spookymooo]

Re Seagull PT19 ARTF(80.5 inches wingspan)

 

Ive just got to the “install engine mount” bit and discovered that the supplied mount is too wide for my Saito 125.

Also discovered an extra firewall piece referencing different engine positions including the Saito 125. ( no reference though in the instructions!!)

Im not sure what to do now as the engine mount captive nuts are pre installed and not accessible to move.

Has anyone else managed to deal with this and how, please?

[Jon H]

If you install the screws into the nuts leaving half inch free play you can easily remove them with a hammer and a sharp tap. If you want you can fill the holes by gluing a dowel in there. once dry cut it off, sand it smooth etc front and back, then set about drilling your new holes. 

 

Should not be a big job

[Spookymooo]

Many thanks Jon…

I will certainly try this but I think the top two captive nuts are in an enclosed section of the fuselage… even if I remove them in the way you suggested refitting them in new positions  might be near impossible without dismantling the fuselage front end.. a serious design fault methinks…

[john stones 1 - Moderator]

Faced with the same issue, I created a hatch underneath forward of the unercariage (not PC 19).

That gave me access with less cosmetic disruption.

[Martin Harris - Moderator]

Isn’t there access to remove the old fittings (using Jon’s method) via the access for the tank “nose” and/or the tank bay?  I’ve fitted replacement blind nuts in the past by using snakes as guides to locate them.  I’ll see if I can find the photo I took of the arrangements. 

[leccyflyer]

 

[Ron Gray]

1 hour ago, Spookymooo said:

Many thanks Jon…

I will certainly try this but I think the top two captive nuts are in an enclosed section of the fuselage… even if I remove them in the way you suggested refitting them in new positions  might be near impossible without dismantling the fuselage front end.. a serious design fault methinks…

I've used these several times before when I've changed engines and had to put in fixings and no access to the rear of the firewall. Apply a bit of cyano to the threads before winding them into the ply.

[Dale Bradly]

Some more ways to skin this cat. Some ideas ive used before:

1. Bolt the engine mount to a piece of ply at the spacing to suit your engine. Then bolt the ply to the firewall using the existing blind nuts. Thus your piece of ply has become an "adaptor" between the spacing you have and the spacing you want.

2. Bolt the engine mount in. Cut a ply or similar material mounting plate that will bridge the gap between the mount and engine lugs.

3. Replace the engine mount with something that provides some/more adjustment that will allow your engine to fit

[Martin Harris - Moderator]

I've found the photos of my simple method:

 

 

First, drill your new holes, push a snake inner through the hole and work it through the tank bay until the end emerges into the fuselage where you can get at it.  Drop the tee nut onto it, followed by the snake outer.  Push the tee nut back to the firewall and holding pressure on the outer, start a bolt from the outside of the firewall. 

 

 

 

Tighten the bolt until the spikes grip, then continue to pull it into the wood.  You can pre-butter it with epoxy if required.

[Spookymooo]

Thanks to everyone who has replied… much appreciated!

I think the best option is to use the reversed fixings as two of the pre installed ones are in a non accessible chamber of the construction and the replacements would have to be in the same area..

just amazed that such an expensive ARTF has this issue!

[J D 8 - Moderator]

          It is difficult for model producers as engine makers all seem to have different mounting positions.

[Spookymooo]

Totally agree… but therefore should have been part of the design brief and fully referenced in the assembly pamphlet and not built with pre installed captive nuts in unaccessible areas assuming just one engine size.

Edited May 1 by Spookymooo

[Geoff S]

14 hours ago, Ron Gray said:

I've used these several times before when I've changed engines and had to put in fixings and no access to the rear of the firewall. Apply a bit of cyano to the threads before winding them into the ply.

 

I use those threaded inserts from Modelfixings quite often and they're very secure even without adding any adhesive to the threads.  My only regret is that they don't go down to 3mm but that wouldn't be a problem for this application.

[Frank Skilbeck]

You say there is an extra firewall piece, could this be an adapter plate? Do you have a photo of the additional firewall.

[Spookymooo]

Yes… its too thin to support mounting captive nuts… ply is probably 1/8” thick , if that.

im assuming its a location aid and ids different engines and hole positions.

[GrumpyGnome]

Probably a template of where to drill holes if you have one of the 'recommended' engines or motors

[Manish Chandrayan]

On 01/05/2024 at 00:45, Spookymooo said:

Many thanks Jon…

I will certainly try this but I think the top two captive nuts are in an enclosed section of the fuselage… even if I remove them in the way you suggested refitting them in new positions  might be near impossible without dismantling the fuselage front end.. a serious design fault methinks…

Once you have determined the correct (new) positions for the mounting holes on the firewall drill and install threaded inserts.

Having taken a look at the manual, I see that the fuel tank needs to be installed through the wing opening in the fuse and the tank neck sits in a hole in the firewall.

Two methods come to my mind, if the tank can reach the firewall so can a blind nut, using the methods suggested by other members to guide the blind nut in position. 

The other way would be to enlarge the tank hole, insert the blind nut, using a finger through the hole to guide and support it while using the other hand and suitable magnet guide the blind nut till it seats in the drilled hole. While still being supported thread the screw and tighten till completely seated in wood, repeat three more times.

If you are worried about the enlarge hole fill that up with some hard foam to support the tank neck   

Edited May 2 by Manish Chandrayan

[Spookymooo]

Thanks Manish..

what the manual doesn’t show is that two of the pre installed captive nuts are in separate sealed off section (not the tank area) so impossible to access with fingers or rods or anything..

I will probably need to disassemble the front of the fuselage to correct the problem 😢

[Dale Bradly]

I really think you're overthinking this. No need to "disassemble the front of the fuselage". 

Im looking at the manual, to understand whats going on, and any one of the ideas i have already posted will solve this.

Furthermore, inverting the engine mount from what the plan shows will give plenty of room to fit a mounting plate between the (inverted) engine bearers and the engine, while keeping the engine at the right height. Cutting one piece of ply is a lot easier than dismantling and rebuilding the front of the fuselage. 

[Spookymooo]

There is an enclosed compartment behind the firewall where the reinstalled captive nuts are not accessible. I will try and take a photo of the zone… if I can remove and extricate the existing nuts and fill the holes, I will insert the reverse threaded inserts from the front in the correct positions… installing the engine (right way up) is a good thought (I hate inverted engine installs)

cheers

rob

[Dale Bradly]

Just to be clear, i didn't recommend mounting the engine the right way up. I said invert the mount and then hang then engine inverted off it.

If you mount the engine the right way up, your cowl won't fit, or you'll arkwardly have the engine poking out the top of the cowl. Again, you seem to be complicating what is a simple solve to a simple challenge.

Here's what i'd do in this case.

This is a pic from the manual, with about 30 seconds of MS Paint's finest cad:

The red lines indicate the engine centre line if it was all done as per Seagull intended.

So I'd invert the engine mounts, and faste to the factory fitted blind nuts. Notice i have done this in this picture. No redrilling, no trying to fish out inaccessible blind nuts, no filling holes etc.

Some packers (green), and a ply plate (yellow).

You cut out the yellow plate to suit your engine.

The end result is your smaller engine remains inverted (as per manual), centered on the red lines (as per manual), but because of the green & yellow spacers, your smaller engine fits to the supplied engine mounting spacing.

I hope this is clear.

 

 

[john stones 1 - Moderator]

Sounds the same as my Seagull Funky Cub, there was no way to remove and replace the captive nuts, a floor supporting the curved upper formers blanks access to it. The simplest and less damaging way of tackling it, is to fashion a hatch underneath the tank bay, via this hatch you can cut some of the floor away to get at the captives.

[Spookymooo]

Thank you… fully understood and very helpful..

what would you recommend for the plate material..

years ago I think we used something called paxolin… but I guess it might be ply or aluminium these days.

heres a pic of behind the firewall..

thanks again

(I’ve just seen you mentioned ply 👍)

Rob

Edited May 3 by Spookymooo
Correction

[Dale Bradly]

5 minutes ago, Spookymooo said:

what would you recommend for the plate material..

Paxolin is great if you can find it.

Ply is absolutely fine. I have also used nylon, in the form of a cheap as chips cutting board from the pound store: Cheap to buy, easy to work, strong as anything.

I don't recommend aluminum for such a plate though.